Immune Responses Regulated by Cannabidiol.

Abstract

Introduction: Cannabidiol (CBD) as Epidiolex^® (GW Pharmaceuticals) was recently approved by the U.S. Food and Drug Administration (FDA) to treat rare forms of epilepsy in patients 2 years of age and older. Together with the increased societal acceptance of recreational cannabis and CBD oil for putative medical use in many states, the exposure to CBD is increasing, even though all of its biological effects are not understood. Once such example is the ability of CBD to be anti-inflammatory and immune suppressive, so the purpose of this review is to summarize effects and mechanisms of CBD in the immune system. It includes a consideration of reports identifying receptors through which CBD acts, since the “CBD receptor,” if a single one exists, has not been definitively identified for the myriad immune system effects. The review then provides a summary of in vivo and in vitro effects in the immune system, in autoimmune models, with a focus on experimental autoimmune encephalomyelitis, and ends with identification of knowledge gaps.

Conclusion: Overall, the data overwhelmingly support the notion that CBD is immune suppressive and that the mechanisms involve direct suppression of activation of various immune cell types, induction of apoptosis, and promotion of regulatory cells, which, in turn, control other immune cell targets.

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Keywords: cannabidiol, immune response, inflammation

Article notes

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Collection date 2020 Mar 1.

Author notes

Cannabidiol History and Therapeutic Uses

Cannabidiol (CBD) is a plant-derived cannabinoid that has structural similarity to the primary psychotropic congener in cannabis, Δ⁹-tetrahydrocannabinol (THC). While CBD was initially isolated in the 1940s, its structure was not elucidated until the 1960s.^1,2 Unlike THC, CBD is bicyclic, comprised a terpene and an aromatic ring, and is a pentyl side chain.¹ It exists as two enantiomers, and it is (−)CBD³ that is one of the major constituents found in Cannabis sp., and will be the focus of this review. For many years, THC and CBD were designated as psychoactive and nonpsychoactive, respectively, owing to the fact that THC produces the euphoric high associated with cannabis use, while CBD does not. However, since we know that CBD produces biological effects in the central nervous system (CNS), perhaps it is better defined as psychoactive, but not psychotropic, since it is active in the CNS without producing the euphoric high.

Perhaps it was the association of the euphoric high with THC that provided the initial focus on THC as opposed to CBD for potential medical use, since THC was originally identified as the active component of the plant.⁴ However, in recent years, researchers have begun to explore CBD more as a therapeutic addition or alternative to THC. In the United States, oral THC (dronabinol, Marinol^®) was first approved in 1985 by the Food and Drug Administration (FDA) to treat nausea and vomiting associated with chemotherapy. In 1992, dronabinol was also approved to treat cachexia in AIDS patients.⁵ The next major advancement in cannabinoid pharmaceuticals was not until the mid-2000s when Sativex^® (nabiximols), a combination of THC and CBD as an oromucosal spray, was approved in Canada and the EU for neuropathic pain in multiple sclerosis (MS) and intractable cancer pain.⁶ There are several reasons why combining THC and CBD in a single therapeutic could have value.⁶ First, additional therapeutic benefit might be gained from hitting multiple targets; for example, if THC alleviates pain and CBD alleviates anxiety,^7–16 the combination therapy could be quite effective for chronic pain sufferers. Second, for disease states in which both THC and CBD are efficacious, a combination might allow for lower doses of THC, thereby potentially decreasing the psychotropic effects of THC. Third, there are some studies suggesting pharmacokinetic interactions between CBD and THC in which CBD treatment increases THC levels,^17–20 thereby allowing longer duration of effects of THC. Sativex^® has been evaluated in several clinical trials for spasticity associated with MS, neuropathic pain, and other conditions.^21–37

The latest approved cannabinoid pharmaceutical in the United States is CBD as Epidiolex^®. It was approved by the U.S. FDA in 2018 for epilepsy in children, in particular, for Dravet Syndrome and Lennox-Gastaut Syndrome.^38–42 CBD is also being investigated for its effectiveness in other diseases, including Tuberous Sclerosis, a genetic condition that causes growth of benign tumors all over the body,^43,44 schizophrenia,⁴⁵ and refractory epileptic encephalopathy.⁴⁶

In addition to the federally approved uses of CBD as Epidolex^®, CBD, usually as CBD oil, is widely used for putative medical benefit in several states, and is certainly used in states in which cannabis has been decriminalized, or legalized, for recreational use.⁴⁷ There are reports that CBD and other cannabinoids are beneficial for sleep, anxiety, pain, post-traumatic stress disorder, schizophrenia, neurodegenerative disorders, and immune-mediated diseases.⁴⁸ Often these conditions are self-diagnosed and self-treated, so there can be issues with dosing, other drug interactions, and characterization of CBD safety and efficacy.

Overall, it is clear that exposures to CBD are increasing.^47,49–51 It is also clear that CBD possesses therapeutic benefit, and in some cases, the beneficial effects of CBD are for diseases for which other available treatments have not been efficacious.⁵² Together, these observations demonstrate the critical need to continue research on CBD, and therefore the goal of this review is to provide a summary of the effects and mechanisms by which CBD alters immune function. The review will include an evaluation of the role for various receptors through which CBD acts in the immune system. There will also be a description of CBD effects in animal and human immune responses, a characterization of mechanisms by which CBD mediates immune effects, and identification of knowledge gaps regarding CBD's actions in the immune system.

Identification of CBD Receptors and Other Targets

Upon identification of the cannabinoid receptors, CBD was determined to exhibit low affinity for CB₁⁵³ and CB₂ receptors.⁵⁴ Consistent with this, we showed CBD-induced suppression of cytokine production in mouse splenocytes in both wild-type and double cannabinoid receptor knockout mice (Cnr1^−/−/Cnr2^−/− mice).⁵⁵ Another study demonstrated that ophthalmic administration of CBD following corneal inflammation reduced neutrophils in both wild-type and CB₂ receptor knockout mice.⁵⁶ CBD-mediated suppression of anti-CD3-mediated proliferation of T cells also occurred in both wild-type and CB₂ receptor knockout splenocytes.⁵⁷ However, there are a few reports using inflammatory stimuli in which CBD's actions have been attributed to either CB₁ or CB₂ receptors (Table 1). In a sepsis model induced with bacterial lipopolysaccharide (LPS), CBD-mediated inhibition of gastric emptying was reversed with the CB₁ receptor antagonist, AM251.⁵⁸ Similarly, CBD inhibited interleukin (IL)-1 in a hypoxia-ischemia brain insult model and this effect was reversed with the CB₂ receptor antagonist, AM630.⁵⁹ Use of ovalbumin to induce an asthma-like disease in mice demonstrated that some cytokines and chemokines induced in the lungs of mice that were suppressed by CBD (IL-4, IL-5, IL-13, and eotaxin) were differentially regulated by CB receptors.⁶⁰ Specifically, CBD-induced suppression of IL-5 was reversed in the presence of the CB₂ receptor antagonist in bronchoalveolar lavage fluid and lung tissue, but there was no clear receptor dependence identified for CBD's suppression of IL-4, IL-13, or eotaxin.⁶⁰ Thus, several studies do suggest a possible role for cannabinoid receptors in CBD-mediated suppression of inflammatory effects. It should also be noted that there are several reports suggesting that CBD acts as an allosteric modulator of CB₁ or CB₂ receptors,^61–64 although the role for CB₁ or CB₂ receptor allosteric modulation by CBD in immune function has not yet been determined.

Table 1.Receptors Identified in Mediating Cannabidiol Immune Effects

Receptor	Activity	References
CB₁	Agonist	⁵⁸
CB₂	Agonist	^59,60
FAAH	Inhibition	^{58,65–67,84,157,160}
TRPV1	Agonist	^{65,66,74,82–88,105,148,194}
Adenosine A_2A	Agonist	^{89–91,125,164}
PPAR-γ	Activation	^{92–94,96–98,136}
5-HT1a	Agonist	⁵⁹
GPR55	Antagonist	^109,110

Another mechanism by which CBD acts is through inhibition of fatty acid amide hydrolase (FAAH),^65–67 suggesting that some of CBD's effects are mediated by anandamide elevation since FAAH is responsible for the breakdown of anandamide.^65,66 Anandamide is an endogenous cannabinoid that exhibits affinity for CB₁ and CB₂ receptors.^68,69 A recent study suggested that the mechanism by which CBD elevates anandamide involves CBD interaction with fatty acid binding proteins, which prevents anandamide binding to these proteins to block anandamide transport to FAAH.⁶⁷ Since anandamide exhibits affinity for CB₁ and CB₂ receptors, and oxidation products of anandamide through cyclooxygenase or cytochrome P450 enzymes produce metabolites that also exhibit affinity for CB₁ and CB₂ receptors,^70,71 anandamide or its metabolites could account for some of the reports that CBD acts through CB₁ and/or CB₂ receptors.^{58,61–64,72–84}

Actions of CBD in immune function might also be mediated by the transient receptor potential V1, known as the vanilloid receptor (TRPV1), which was found to be activated by CBD.⁶⁵ Specifically, CBD was found to increase intracellular calcium in HEK cells transfected with TRPV1, and the CBD-induced increase in calcium was blocked by the TRPV1 antagonist, capsazepine.^65,66 Follow-up studies demonstrated that CBD desensitizes TRPV1 following activation.⁸⁵ Other studies have suggested that CBD acts through TRPV1 in the immune system (Table 1). CBD can induce myeloid-derived suppressor cells (MDSCs), a type of regulatory cell, in the liver, and this effect is lost in TRPV1 knockout mice.⁸⁶ Specifically, regarding inflammation, CBD attenuated thermal hyperalgesia in response to carrageenan injections or in a neuropathic pain model in a capsazepine-dependent manner.^87,88 CBD suppression of cytokines in inflamed primary human colonic tissue was attenuated by the TRPV1 antagonist, SB366791.⁸² SB366791 was also effective in reversing CBD's suppression of rolling and adherent leukocytes in the sodium monoiodoacetate model of osteoarthritis in rats.⁸³ Together, these data suggest that TRPV1 is a critical receptor through which CBD acts in the immune system.

There have been several critical articles in which adenosine A_2A receptors have been shown to mediate CBD's effects in the immune system.^89–91 CBD was shown to inhibit microglial cell proliferation, which was associated with inhibition of adenosine uptake into cells.⁸⁹ The studies also demonstrated that CBD suppression of tumor necrosis factor-alpha (TNF-α) could be reversed using an adenosine A_2A receptor antagonist, and CBD-induced suppression of LPS-stimulated TNF-α was not observed in adenosine A_2A receptor knockout mice.⁸⁹ The role for adenosine A_2A receptor in CBD-mediated neuroprotection or suppression of neuroinflammation was demonstrated in a model of hypoxia-ischemia in newborn mouse brains.⁹⁰ CBD inhibited adenosine uptake into rat microglial cells and CBD enhanced adenosine's ability to inhibit TNF-α, which was prevented by the adenosine A_2A receptor antagonist, ZM241385.⁹¹ These studies show that CBD acts through the adenosine A_2A receptor, especially in microglial cells.

CBD's effects have also been shown to be mediated by peroxisome proliferator-activated receptor gamma (PPAR-γ) using PPAR-γ antagonists in models of β amyloid neuroinflammation,⁹² apoptosis,^93,94 dinitrobenzene sulfonic acid (DNBS)-induced colitis,⁹⁵ human ulcerative colitis,⁹⁶ LPS activation of microglial cells,⁹⁷ and hypoxia-ischemia model of neuroinflammation.⁹⁸

There are several reports that CBD acts through the serotonin 5-HT1a receptor (Table 1). Although most of the evidence for the involvement of this receptor comes from the attenuation of CBD's effects using the 5-HT1a antagonist, WAY100635, early studies demonstrated that CBD displaced binding of the 5-HT1a agonist, 8-OH-DPAT, in membranes from CHO cells expressing the human 5-HT1a receptor.⁹⁹ Few of the CBD-mediated effects acting through the serotonin 5-HT1a receptor have been reported in immune cells, but immune cells do express 5-HT1a.^100–103 One study showed that IL-1 produced in the brain in response to hypoxia-ischemia insult was inhibited by CBD, and reversed with the 5-HT1a receptor antagonist, WAY100635.⁵⁹

Studies have suggested that CBD might act through other receptors, including other TRP receptors,^{66,85,104–107} or opioid receptors.¹⁰⁸ There is also evidence that CBD acts through blockade of GPR55,¹⁰⁹ and specifically that CBD modestly antagonized proinflammatory effects in human innate cells following GPR55 activation.¹¹⁰ Thus, together, the current data support that immune effects of CBD are mediated through activation of CB₁, CB₂, TRPV1, adenosine A2A, and PPAR-γ receptors, blockade of GPR55 receptors, and FAAH inhibition.

CBD Immune System Effects and Mechanisms

Immunity is maintained through various cell types acting together to provide protection against foreign invaders, and simultaneously avoid reactions against self-proteins. Thus, an appropriate immune response requires a regulated balance between robust reactions against non-self, but limited or no reactions against self. Cell types include neutrophils, macrophages, and other myeloid cells comprising the innate immune system, which reacts quickly to destroy pathogens. In the event that an innate response is insufficient, certain innate cells can activate the adaptive immune response, comprised predominantly of T and B cells. T cells can then provide signals that recruit and activate other immune cells, or directly lyse or induce apoptosis of infected cells. T cells can also help stimulate B cells, which produce antibodies to neutralize pathogens and/or enhance destruction of the pathogens. Communication between the various cell types, and therefore the innate and adaptive immune responses, is mediated by expressed or secreted proteins called cytokines or chemokines. Inflammation is the process commonly associated with the innate immune response since pathogen destruction can also cause tissue damage, although T cells certainly are proinflammatory as well. In fact, many cell types, regardless of whether they are immune cells, produce proinflammatory cytokines in response to inflammation.

The effects of CBD on immune responses can involve innate or adaptive responses. In assessing these responses, various cell types and their functions have been examined. For instance, a common end-point to examine regardless of cell type is cytokine or chemokine production. Typical proinflammatory cytokines include IL-1α, IL-1β, IL-6, TNF-α and IL-17A, while IL-10 is considered anti-inflammatory. Some cytokines are produced by specific T cell subsets; for instance, the Th1 subset produces interferon-gamma (IFN-γ) and promotes cell-mediated cytotoxicity, while the Th2 subset produces IL-4 and promotes B cell responses. Other end-points that might provide clues of disruption of immune competence are nitric oxide or myeloperoxidase (MPO) production from innate cells, as these are often released during pathogen destruction. Thus, the effects of CBD on immune function are presented by cell type, outlining known mechanisms by which CBD alters various end-points. Tables 2–4 include the studies described in the text (and others) and are organized by experimental approach. As indicated above, inflammation can induce proinflammatory cytokine production in nonimmune cells, so there are also a few of those examples included in the tables.

Table 2.Cannabidiol-Induced Immune Suppression by Cell Type in Human Cells In Vitro

Cell type	End-point(s)	References
PBMCs	↓rosette formation	^138a
PBMCs	↓cytokines	^111,112a
Human cell lines^b	↓cytokines	¹⁸⁶
HL-60^b	↑apoptosis	¹¹³
Jurkat and MOLT-4 T cells^b	↑apoptosis	^80a
Human coronary artery endothelial cells	↓adhesion molecules, migration, transcription factors, nitrative stress	^119a
Jurkat T cells^b	↓cytokines, transcription factors	^55a
Human neutrophils	↓migration	¹⁹⁵
PBMCs	↓indoleamine-2,3-dioxygenase (IDO), ↓cytokines	¹⁴²
THP-1 cells^b	↓IDO	¹⁴²
PBMCs	↑apoptosis	^114a
Human intestine	↓proteins and nitric oxide	⁹⁶
Human liver sinusoidal endothelial cells	↓adhesion molecules	¹¹⁸
Human gingival mesenchymal stem cells	↓inflammatory genes	⁷⁹
Caco-2 cells^b	↓phosphoproteins	^82a
Primary colonic explants	↓cytokines	^82a
Human neutrophils	↓ROS	¹⁸⁵
Human PBMCs	↓proliferation and cytokines	^146a
HaCaT human keratinocytes^b	↓cytokines	⁸⁴
Human monocytes	↑apoptosis	^115a
Human plasmacytoid dendritic cells	↓CD83 expression in HIV⁺ dendritic cells	^134a

Table 3.Cannabidiol-Induced Immune Suppression by Animal Cell Type In Vitro

Cell type	End-point(s)	References
B6C3F1 female splenocytes	↓IL-2	¹⁹⁶
EL-4 T cells^a	↑apoptosis	^80b
Mouse EOC-20 microglial cells^a	↓proliferation	^89b
BALB/c male splenocytes	↓IL-4 and IFN-γ	^140b
B6C3F1 female splenocytes	↓IL-2 and IFN-γ	^55b
BALB/c male thymocytes and EL-4 T cells^a	↑apoptosis	^150b
BALB/c male splenocytes	↑apoptosis	^151b
Sprague-Dawley rat microglial cells^c	↓adenosine uptake,	^91b
Sprague-Dawley rat microglial cells^c	↓TNF-α	^91b
BV-2 cells^a	↓cytokines, ↓NF-κB activation	^147b
Mouse brain slices^c	↓cytokines	^90b
Rat male astroglial cells	↓gliosis	^92b
C57BL/6 male Kupffer cells	↓TNF-α	¹¹⁸
BALB/c microglial cells^c	↑apoptosis	^156b
BV-2 cells^a	↓oxidative stress, ↓Ccl2	¹⁵⁹
MOG-specific female T cells	↓IL-17A and IL-6	^144b
Mouse brain endothelial cells^a	↓VCAM-1 and leukocyte adhesion	^164b
Rat astrocytes^c	↓Ccl2	^164b
RAW cells^a	↓TNF-α	¹⁴⁸
MOG-specific female T cells	↓cytokines	^143b
Rat male splenocytes and mesenteric lymph nodes	↓proliferation and cytokines	^146b
Primary mouse male and female microglial cells	↓activation	^97b
BV-2 cells^a	Alteration of circadian rhythm-associated genes	¹⁹⁷
BV-2 cells^a	alteration of miRNAs	^161b
C57BL/6 or BALB/c female splenocytes	↓proliferation and cytokines	⁵⁷

Table 4.Cannabidiol-Induced Immune Suppression in Animals In Vivo

Model	Disease model	Route, dose range, and duration/frequency^a	Major effects	Reference
Male CD-1 mice	sRBC	i.p.	Modest ↓antibody production	¹⁵⁵
		25 mg/kg
		4 days
Male DBA/2 mice	Collagen-induced arthritis	i.p. or oral	↓disease, ↓TNF-α and IFN-γ	^139b
		2.5–20 mg/kg for i.p.
		5–50 mg/kg for oral
		10 days
Male ICR mice	Carrageenan-induced inflammation	ethosome (CBD in ethosomal gel)	↓inflammation	¹⁹⁸
Male ICR mice	Carrageenan-induced inflammation	100 mg of ethosomal CBD (3%)	↓inflammation	¹⁹⁸
Male Wistar rats	Carrageenan-induced inflammation	Oral	↓disease, ↓prostaglandin (PGE₂)	¹⁹⁹
		5–40 mg/kg
		3 days
Female NOD mice	Diabetes	i.p.	↓disease incidence, ↓IL-12, TNF-α and IFN-γ, ↑IL-4	¹²³
		5 mg/kg/day
		10–20 injections
Female C57BL/6 mice	EL-4 leukemia growth	i.p.	↑apoptosis of tumor cells	^80b
Female C57BL/6 mice	EL-4 leukemia growth	12.5 or 25 mg/kg once	↑apoptosis of tumor cells	^80b
Male Wistar rats	Sciatic nerve pain or CFA-induced inflammation	Oral	↓pain, ↓TNF-α, ↓prostaglandin (PGE₂)	⁸⁸
		2.5–20 mg/kg
		7 days
Male Sprague-Dawley rats	Ischemia-reperfusion injury (myocardial)	i.p.	Modest ↓infarct size, ↓TNF-α	²⁰⁰
		5 mg/kg
		twice
C57BL/6J mice^c	Aβ inflammation	i.p.	↓IL-1β, ↓iNOS	¹¹⁷
		2.5 or 10 mg/kg
		7 days
Male BALB/c mice	Ovalbumin (asthma)	i.p.	↓serum antibodies, ↓IL-2, IL-4, and IFN-γ	^140b
		5–20 mg/kg
		once
Male ddY mice	Focal cerebral ischemia	i.p.	↓infarct size, ↓neutrophil MPO activity	^129b
		3 mg/kg
		various times surrounding occlusion
Female NOD mice	Diabetes	i.p.	↓disease incidence, ↓IL-6 and IL-12, ↑IL-4 and IL-10	^124b
		5 mg/kg/day
		5 injections per week for 4 weeks
Female B6C3F1 mice	sRBC	Oral	Modest ↓antibody production	^55b
		25–100 mg/kg/day
		5 days
Male ICR mice	DNBS colitis	i.p.	↓inflammation, ↓colon weight:length ratio, ↓iNOS, IL-1β, ↑IL-10	^95b
		1–10 mg/kg
		6 days
Male Wistar rats	None	i.p.	↓blood leukocytes and lymphocytes, ↓B, T and CTL cells, ↑NK and NKT cells	²⁰¹
		2.5 or 5 mg/kg
		14 days

Male CD-1 mice	Diabetes	i.p. or i.n.	↓diabetic pain, ↓density of microglial cells	^81b
		0.1–2 mg/kg i.n.
		1–20 mg/kg i.p.
		3 months
Male C57BL/6 mice	Streptozotocin-induced diabetes	i.p.	↓disease, ↓TNF-α, NF-κB activity, ICAM-1, VCAM-1, iNOS, p-p38, p-JNK, ↑p-AKT	^120b
		1–20 mg/kg
		11 weeks
Male Wistar rats	TNBS colitis	i.p.	Modest ↓disease, ↓colonic contractions, ↓neutrophil MPO activity	¹³⁰
		5–20 mg/kg
		once
Male Wistar rats	Cecal ligation and puncture	i.p.	↑disease survival	¹⁸⁴
		2.5–10 mg/kg
		once or up to 9 days
Female Sabra mice	Hepatic encephalopathy (bile duct ligation)	i.p.	Improved disease-associated cognitive impairments, ↓TNF-α	²⁰²
		5 mg/kg
		4 weeks
Male BALB/c mice	Ovalbumin (footpad)	i.p.	↓footpad swelling, ↓TNF-α and IFN-γ, ↑IL-10	¹⁸⁸
		1–10 mg/kg
		5 days
Male Swiss OFI mice	LPS i.p.	i.p.	↓mast cell infiltration, macrophage activation marker, ↓TNF-α	⁹⁶
		10 mg/kg
		twice
Female C57BL/6 mice	Experimental autoimmune hepatitis	i.p.	↓hepatic inflammation, ↓IL-2, TNF-α, IFN-γ, IL-6, IL-17A, IL-12, MCP-1 (CCL-2), and eotaxin, ↑MDSCs	^86b
		10–50 mg/kg
		once
Male C57BL/6 mice	Ischemia reperfusion injury (liver)	i.p.	↓hepatic inflammation, ↓MIP-1α, ICAM, MIP-2, TNF-α, NF-κB activity, ICAM-1, iNOS, p-p38, p-JNK	¹¹⁸
		3 or 10 mg/kg
		once
C57BL/6 mice^c	LPS i.v.	i.v.	↓vasodilation, leukocyte margination, and extravasation, ↓COX-2, TNF-α, and iNOS	¹²¹
		1 or 3 mg/kg
		once
Male C57BL/6 mice	LPS-induced pulmonary inflammation	i.p.	↓BALF lymphocytes, macrophages, and neutrophils, ↓TNF-α, IL-6, MCP-1 (CCL-2), and MIP-2	^125b
		0.3–80 mg/kg
		once
Male Wistar rats	Meningitis (Streptococcus pneumoniae)	i.p.	Improved disease-associated cognitive impairments, ↓TNF-α	²⁰³
		2.5–10 mg/kg
		once or up to 9 days
C57BL/6 mice^c	Cerulein (pancreatitis)	i.p.	↓disease, ↓TNF-α and IL-6, ↓neutrophil MPO	^128b
		0.5 mg/kg
		twice
Newborn pigs^c	Hypoxia-ischemic brain injury	i.v.	neuroprotection, ↓IL-1	^59b
		1 mg/kg
		once
Male Wistar rats	Ovalbumin (asthma)	i.p.	↓TNF-α, IL-6, IL-4, IL-5, and IL-13	^127b
		5 mg/kg
		twice
Male C57BL/6 mice	LPS-induced pulmonary inflammation	i.p.	↓inflammation, ↓BALF lymphocytes, macrophages, and neutrophils, ↓TNF-α, IL-6, MCP-1 (CCL-2), and MIP-2	¹³²
		20–80 mg/kg
		once
Female C57BL/6 mice	None	i.p.	↑MDSCs	^136b
		20 mg/kg
		once
Female C57BL/6 mice	Malaria (Plasmodium berghei)	i.p.	↓IL-6 and TNF-α	²⁰⁴
		30 mg/kg
		3–5 days
Male Sprague Dawley rats	Freund's Adjuvant (osteoarthritis)	Transdermal	↓inflammation, ↓TNF-α	²⁰⁵
		0.6–63.2 mg/day
		4 days
Male ICR mice	DNBS Colitis	i.p. or oral^d	↓colon weight:length ratio, ↓neutrophil MPO	¹³¹
		5–30 mg/kg for i.p. 10–60 mg/kg oral
		3 days
Female NOD mice	Type 1 diabetes	i.p.	↓disease	²⁰⁶
		5 mg/kg
		5 injections/week for 10 weeks
Male A/J mice	Experimental autoimmune myocarditis	i.p.	↓disease, ↓lymphocyte populations in heart, ↓IL-6, IFN-γ, IL-1β, and MCP-1 (CCL-2)	^126b
		10 mg/kg
		46 days
Male Wistar rats	Middle cerebral artery occlusion	i.c.v.	↓infarct size	¹⁴⁹
		50–200 ng/rat
		5 days
Male Wistar rats	Middle cerebral artery occlusion	i.c.v.	↓infarct size, ↓TNF-α	²⁰⁷
		50–200 ng/rat
		5 days
Male Wistar rats	Sodium monoiodoacetate (osteoarthritis)	Intra-arterial	↓pain, ↓rolling and adherent leukocytes, ↓joint nerve demyelination	^83b
		100–300 μg/rat
		multiple doses
Female C57BL/6 mice	Alcoholic liver disease	i.p.	↓liver damage, ↓neutrophils, ↓TNF-α, MIP-1, IFN-γ, IL-1β, and MCP-1 (CCL-2)	¹⁸⁵
		5 or 10 mg/kg
		11 days
Male and female dogs	Osteoarthritis	Oral^e	↓pain	²⁰⁸
		2 and 8 mg/kg
		every 12 h for 4 weeks
Male Wistar rats	Ulcerative tongue lesion	i.p.	↓inflammation	²⁰⁹
		5 or 10 mg/kg
		3 or 7 days
Female C57BL/6 mice	Spinal cord contusion	i.p.	↓spinal cord CD4 T cells, ↓IL-23A, IL-23R, IFN-γ, CXCL9, CLCL11, NOS2, and IL-10	¹⁸⁹
		1.5 mg/kg
		1 and 24 h after injury, on day 3, then twice/week up to 10 weeks
Male Sprague-Dawley rats	Carrageenan-induced inflammation	Oral	↓hyperalgesia	²¹⁰
		100 or 10,000 μg/kg
		once
Male Swiss mice	Haloperidol-induced inflammation	i.p	↓IL-1β and TNF-α, ↑IL-10	^97b
		60 mg/kg
		twice/day up to 21 days
Male BALB/c mice	Corneal inflammation	Topical (ophthalmic)	↓pain, ↓neutrophils	^56b
Male BALB/c mice	Corneal inflammation	3% or 5%	↓pain, ↓neutrophils	^56b
Male ICR mice	Ischemia-reperfusion injury (kidney)	i.p.	↓kidney injury, ↓TH17 cells, ↑Tregs and Treg17 cells	^152b
		10 mg/kg
		once
Female C57BL/6 and BALB/c mice	Syngeneic or allogeneic bone marrow transplant	i.p.	↓lymphocyte recovery	⁵⁷
		5 mg/kg
		every other day for 2 weeks
BALB/c mice	Ovalbumin (asthma)	i.p.	↓airway resistance; ↓IL-4, IL-5, IL-13, and eotaxin	^60b
		5 or 10 mg/kg
		three times at time of ovalbumin challenge

CBD effects and mechanisms of immune suppression in innate cells

One of earliest effects reported with CBD was in human mononuclear cells,^111,112 in which TNF-α, IFN-γ, and IL-1α were all suppressed (0.01–20 μg/mL CBD or 0.03–64 μM CBD). Later studies focused on human monocytic cells revealed that CBD can induce apoptosis in either HL-60 (1–8 μg/mL CBD or 3.2–26 μM CBD)¹¹³ or primary human monocytic cells (1–16 μM CBD).^114,115 Macrophages are also targets, although they have been studied more commonly in animal models. Peritoneal macrophages were used early on to demonstrate that CBD (3 μg/mL or 10 μM) targets nitric oxide,¹¹⁶ and this has also been a well-studied target of suppression by CBD in many tissues and cell types. The mechanism by which CBD suppressed nitric oxide involves suppression of endothelial⁸⁷ or inducible nitric oxide synthase (iNOS)^{58,95,117–121} in response to various inflammatory stimuli. iNOS is known to be regulated by the transcription factor nuclear factor-κB (NF-κB),¹²² which is comprised of p65 and other proteins, and becomes active after degradation of the inhibitory protein, IκB. Decreased expression of iNOS by CBD correlated with stimulation of the inhibitory IκBα protein and inhibition of NF-κB p65 protein expression.^119,120 Using peritoneal macrophages from diabetic mice stimulated ex vivo with LPS revealed that macrophages isolated from CBD-treated mice did not produce as much TNF-α or IL-6 as macrophages isolated from vehicle-treated mice.^123,124 A direct effect of CBD decreasing macrophage numbers in the bronchoalveolar lavage fluid was shown following intranasal LPS administration to induce pulmonary inflammation.¹²⁵ There was also decreased expression of F4/80 (a marker of macrophages) mRNA expression by CBD in heart tissue in experimental autoimmune myocarditis.¹²⁶ Although this study identified CBD only affecting F4/80 mRNA expression as opposed to F4/80 cell surface staining, it does suggest a novel target (i.e., heart tissue) of CBD in a relatively understudied autoimmune model.

IL-6 is a proinflammatory cytokine produced by many cell types, predominantly innate cells. Many studies have shown that circulating IL-6 is readily inhibited by CBD in inflammatory models, including diabetes,¹²⁴ asthma,¹²⁷ pancreatitis,¹²⁸ and hepatitis.⁸⁶ CBD treatment in vivo resulted in lower IL-6 production in peritoneal macrophages stimulated ex vivo with LPS,¹²⁴ in the pancreas in acute pancreatitis,¹²⁸ and in bronchoalveolar lavage fluid in LPS-induced pulmonary inflammation.¹²⁵

There have been some reports that CBD alters neutrophil function. Compromised MPO activity by CBD has been studied in several tissues, including brain,¹²⁹ colon,^130,131 lung,^125,128,132 and pancreas.¹²⁸ Interestingly, in the pulmonary inflammation studies with LPS, neutrophil cell counts in the bronchoalveolar lavage fluid were also decreased by CBD compared to LPS.^125,132 Together, the results suggest that CBD's mechanism for neutrophil suppression involves both decreased numbers of neutrophils and compromised MPO activity.

There are two recent studies focused on CpG stimulation of IFN-α production from human plasmacytoid dendritic cells.^133,134 While these studies are focused primarily on THC and other CB₂ agonists, CBD was also used (1–10 μM) and did not affect IFN-α production.^133,134 It was interesting, however, that CBD suppressed the CD83 dendritic cell activation marker on dendritic cells derived from HIV⁺, but not healthy, individuals.¹³⁴ Reduction in dendritic cell CD83 signaling can compromise T cell function,¹³⁵ although additional studies using CBD in human dendritic cells and T cells are needed to establish the consequences of CBD-induced reduction in CD83 on HIV⁺ dendritic cells.

Another mechanism by which CBD controls immune function is induction of regulatory cells. MDSC are innate, myeloid cells that possess the ability to control immune responses. Hegde et al. demonstrated that CBD induced CD11b⁺Gr-1⁺ MDSCs in the liver in a mouse hepatitis model.⁸⁶ Importantly, the isolated MDSCs were functional, that is, they suppressed proliferation of responder T cells ex vivo and improved liver function when administered before hepatitis induction.⁸⁶ CBD-induced MDSCs from the peritoneal cavity were able to attenuate inflammation in response to LPS.¹³⁶ In the experimental autoimmune encephalomyelitis (EAE) model, CBD induced MDSCs in the peritoneal cavity, but decreased the infiltration of MDSCs in the spinal cord and brain.¹³⁷ CBD-induced MDSCs from the peritoneal cavity were able to attenuate responder T cell proliferation ex vivo and attenuate EAE disease when administered in vivo.¹³⁷

CBD effects and mechanisms of immune suppression in lymphocytes

The area in which most of the effects of CBD in the immune system have been studied is T cells. Early studies examining rosette formation in response to sheep red blood cells (sRBCs) (generally considered to be a T cell response) revealed that CBD (1 and 100 μM) reduced this response.¹³⁸ Phytohemagglutinin (PHA)-stimulated IFN-γ production in T cells has also been shown to be inhibited by CBD (0.01–20 μg/mL or 0.03–64 μM).^111,112 Other studies have provided further evidence that T cell-produced IFN-γ is a critical target of CBD suppression. CBD inhibited IFN-γ production from lymph node cells isolated from arthritic mice stimulated ex vivo with collagen,¹³⁹ and from splenocytes isolated from NOD mice stimulated ex vivo with ConA.^123,124 IFN-γ production from splenocytes isolated from untreated mice was suppressed by CBD following ex vivo stimulation with phorbol 12-myristate 13-acetate/ionomycin (PMA/Io).¹⁴⁰ In the latter study, a 1-h exposure of CBD to the mice was meant to mimic the time for CBD distribution before receiving antigen sensitization with ovalbumin to induce asthma-like disease.¹⁴⁰ Thus, CBD's ability to compromise various cytokines at the time of antigen sensitization might suggest that CBD affects primary activation of T cells, as has been suggested as part of the mechanism for other cannabinoids, such as THC.¹⁴¹ Indeed, we have shown that a 30-min pre-treatment with CBD (0.1–20 μM) suppressed IFN-γ production in mouse splenocytes in response to PMA/Io or anti-CD3/CD28.⁵⁵ In these studies, it was shown that the mechanism by which CBD suppressed IFN-γ occurred at the level of transcription and that two important transcription factors for IFN-γ, activator protein-1 (AP-1) and nuclear factor of activated T cells (NFAT), were inhibited by CBD, suggesting a transcriptional mechanism for suppression.⁵⁵ CBD-induced suppression (0.1–10 μg/mL or 0.3–32 μM) of Ifng mRNA expression was shown using PHA-stimulated human PBMCs.¹⁴² Given the many reports that IFN-γ seems to be a sensitive target of suppression by CBD, it was surprising that Ifng mRNA was not affected by CBD (5 μM) using encephalitogenic T cells stimulated by antigen-presenting cells (APCs) and myelin oligodendrocyte glycoprotein peptide (MOG_35–55) in vitro.¹⁴³ However, CBD did inhibit expression of IFN-γ receptor 1 and CBD increased several IFN-γ-responsive genes known to attenuate T cell proliferation.¹⁴³ Overall, the data reveal that an important part of CBD's action in the immune system is its ability to affect IFN-γ in multiple ways. Not only did CBD directly suppress IFN-γ production through a transcriptional mechanism under several conditions^55,142 but also suppressed IFN-γ receptor expression, and increased IFN-γ-induced genes that subsequently attenuate other immune targets.¹⁴³

A few other T cell-derived cytokines have been shown to be targets of CBD. As noted above, IL-6 is a critical target of CBD in many cells and tissues,^{82,84,86,97,125–128,132} many of which are innate cells. However, IL-6 was also suppressed by CBD (5 μM) using encephalitogenic T cells stimulated by APCs and MOG_35–55 in vitro,¹⁴⁴ and “IL-6 signaling” as a critical pathway suppressed by CBD.¹⁴³ Interestingly, “IL-17 signaling” was also identified as a critical pathway suppressed by CBD (5 μM) in T cells in vitro.¹⁴³ It should be noted that IL-6 promotes the differentiation of TH17 cells,¹⁴⁵ so the simultaneous suppression of IL-6 and IL-17A by CBD is consistent with CBD suppressing TH17 cell differentiation. Indeed, CBD (1–20 μg/mL or 3.2–64 μM) suppressed IL-17A production in human CD3⁺ T cells (derived from healthy patients or patients with MS or nonseminomatous germ cell tumors) stimulated ex vivo with PMA/Io.¹⁴⁶ Taken together with the data described in innate cells above, it is clear that CBD's action in inflammation and immune function involves suppression of cytokine production from many different cell types.

The ability of CBD to suppress transcription factors such as NFAT, AP-1, and NF-κB likely accounts for its widespread suppression of many cytokines.^{74,82,118–120,147–149} Some of the studies suggest that CBD increased, or perhaps stabilized, expression of IκB as part of the mechanism by which it suppresses NF-κB.^119,120,147 CBD (4 μM) stimulated IκB-α expression in high glucose-treated human coronary artery endothelial cells.¹¹⁹ CBD induced expression of IκB-α in heart tissue from diabetic mice in vivo¹²⁰ and in LPS-stimulated microglial cells in vitro (CBD 1–10 μM).¹⁴⁷ It is interesting that NF-κB activity has not yet been identified as a target in T cells, suggesting that CBD-mediated suppression of NF-κB plays a bigger role in mediating anti-inflammatory effects in non-T cells.

Certainly, some of the dysregulation of these transcription factors is the result of suppression of various kinases upstream of their activation. Extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase (JNK), and p38 MAPKs have all been identified as targets of suppression by CBD in various cell types.^{74,80–82,118,120} Of these reports, one was conducted in human T cells.⁸⁰ In these studies, CBD (5 μM) was shown to suppress expression of total and phosphorylated p38 at the 16-h timepoint following CBD treatment. The authors also showed that the CBD-mediated inhibition of phosphorylated p38 was reversed by SR1445328 or tocopherol, suggesting that CBD acts through CB₂ and that the mechanism of suppression involves reactive oxygen species (ROS) production.⁸⁰

Although well studied in cancer cell lines and primary tumor tissue, CBD-mediated apoptosis is also a contributor to the immune suppressive mechanism. Initially CBD-induced apoptosis in T cells was described in Jurkat and MOLT4 human T cells.⁸⁰ In the same study, McKallip et al. observed increased apoptosis of mouse lymphoma cells injected into, and then recovered from, the peritoneal cavity of mice that were treated with CBD.⁸⁰ Since then, there has been a series of studies characterizing the mechanisms by which CBD induced apoptosis in mouse immune cells. CBD (1–16 μM) was shown to induce apoptosis in mouse thymocytes and EL-4 T cells.¹⁵⁰ The same group demonstrated that CBD (1–16 μM) induced apoptosis in mouse splenocytes, including assessment of CBD-induced apoptosis by cell type (B220⁺ B cells and CD4⁺ and CD8⁺ T cells).¹⁵¹ In both studies, CBD increased ROS, and CBD-mediated apoptosis was attenuated by N-acetylcysteine.^150,151 Wu et al. further demonstrated that the CBD increased ROS-activated caspase-8 to mediate apoptosis.¹⁵¹ In follow-up studies in human monocytes, Wu et al. noted that CBD (1–16 μM) readily induced apoptosis, but that the effect of CBD on apoptosis was lost if the monocytes were pre-cultured for 72 h.¹¹⁴ The authors suggest that the differential responsiveness to CBD was due to an increase in antioxidant capacity in cultured cells, which is a thought consistent with the mechanism by which CBD induced apoptosis in mouse lymphocytes.^150,151 CBD-induced apoptosis (1–16 μM CBD) in human monocytes was due to a cascade of intracellular events, including opening of the mitochondrial permeability transition pore, depolarization of the mitochondrial membrane potential, oxidation of a lipid in the mitochondrial inner membrane, and mitochondrial ROS generation, leading to cytochrome C release.¹¹⁵ Thus, this latest study demonstrates a critical role of the mitochondria in CBD-induced apoptosis.

Another important mechanism by which CBD acts to control immune responses is through regulatory T cell (Treg) induction. In the ConA model of hepatitis, CBD modestly enhanced Tregs in the liver as quantified by CD4⁺Foxp3⁺ cells.⁸⁶ A confirmation of in vivo induced Tregs by CBD was noted in an ischemia-reperfusion injury model in the kidney, in which CBD returned the disease-induced reduction in CD3⁺Foxp3⁺ cells to baseline.¹⁵² Interestingly, in the ischemia-reperfusion kidney model, CBD also induced “TReg17 cells,” which were defined as CD3⁺Foxp3⁺CCR6⁺STAT3⁺.¹⁵² It has been suggested that Treg17 cells help control a TH17 response. In vitro, CBD (5 μM) induced a CD69⁺LAG⁺ population in CD4⁺CD25⁻ cells, which were identified as one type of regulatory cell, and induced Il10 mRNA expression.¹⁵³ We showed in vitro that CBD (1–15 μM) induced functional CD4⁺CD25⁺Foxp3⁺ T cells under conditions of suboptimal stimulation and that Il10 mRNA expression was induced.¹⁵⁴

There are only a few studies in which B cells are identified as targets of CBD. CBD given at 25 mg/kg by intraperitoneal (i.p.) injection modestly reduced the sRBC-induced plaque-forming cells, which is a measure of antibody production.¹⁵⁵ We conducted a similar study using oral administration of CBD and also found modest inhibition of antibody production.⁵⁵ Other studies have shown that CBD robustly inhibited the sRBC-induced antibody production in vitro,⁵⁵ suppressed ovalbumin-induced IgM, IgG1, and IgG2a in an in vivo asthma model,¹⁴⁰ and reduced expression of activation markers such as major histocompatibility complex II, CD25, and CD69, on B cells.¹⁵³ CBD has also been shown to induce apoptosis in B cells.¹⁵¹ Overall, the results suggest that B cells can be targets of suppression by CBD.

CBD-induced neuroprotection by suppression of microglial cell activation

There is no doubt that many of the mechanisms already identified for innate cells and lymphocytes also account for CBD's ability to decrease microglial cell activation. CBD (1–16 μM) induced apoptosis in microglial cells,¹⁵⁶ which was dependent on activation of caspase 8 and 9, and was reversed in the presence of an agent that depletes cholesterol and disrupts lipid rafts.¹⁵⁶ These results suggest that CBD-induced apoptosis is dependent on lipid raft formation,¹⁵⁶ and indeed, this observation was confirmed by another group in BV-2 microglial cells.¹⁵⁷

BV-2 microglial cells have been used as a model in several articles, in which detailed transcriptional effects of CBD have been evaluated.^{147,157–159} The mechanisms contributing to CBD (10 μM)-mediated suppression of LPS-stimulated cytokine production in microglial cells includes decreased activation of the Toll/IL-1 receptor domain-containing adapter-inducing IFN-β (TRIF)/IFN-β/signal transducer and activator of transcription (STAT) signaling pathway.¹⁴⁷ CBD suppressed LPS-stimulated NF-κB activation, and induced LPS-stimulated STAT3 activation, which has been shown to suppress NF-κB activation.¹⁴⁷ CBD (10 μM) was shown to affect several genes involved in lipid metabolism in unstimulated BV-2 cells,¹⁵⁷ which might account for CBD's ability to increase anandamide^{58,65–67,84,157,160} or could account for CBD's dependence on lipid raft formation to induce apoptosis^156,157 Follow-up studies examining CBD's effects in unstimulated BV-2 cells demonstrated that CBD (10 μM) alters zinc homeostasis, oxidative stress, and glutathione levels in microglial cells.^158,159 A recent study demonstrated that CBD alters microRNA (miRNA) expression,¹⁶¹ and two of the CBD miRNA targets identified are discussed. First, CBD downregulated miR146-a, which acts as a negative regulator of inflammation, in both resting and LPS-stimulated cells, thereby contributing to CBD's ability to downregulate proinflammatory cytokines.¹⁶¹ Second, CBD upregulated miR-34a, which has several roles in cell survival, such as cell cycle, apoptosis, and differentiation.¹⁶¹ These results show that CBD-induced alterations in miRNA expression are involved in the mechanism by which CBD suppresses immune function.

In vivo, CBD has been shown to decrease microglial accumulation in the spinal cord in diabetic mice,⁸¹ which might contribute to attenuation of neuropathic pain, and CBD decreased haloperidol-induced activation of reactive microglial cells.⁹⁷ CBD's suppression of TNF-α production from microglial cells in vitro was mediated by A_2A adenosine receptors in EOC-20 mouse microglial cells (0.5–5 μm)⁸⁹ or rat retinal microglial cells (1 μM).⁹¹

CBD Effects in Autoimmune Disease Models

EAE and MS

The immunosuppressive and neuroprotective mechanisms of CBD make it an ideal therapeutic candidate for MS, a neurodegenerative autoimmune disease of the CNS that affects ∼2.5 million people worldwide. The average age of onset is around 30 years, and symptoms can vary greatly for each patient based on the lesion locations within the CNS.¹⁶² Two models frequently used in the laboratory environment to study MS are the EAE and Theiler's murine encephalomyelitis virus (TMEV) models, and an increasing number of studies have shown promising results with CBD using these models (Table 5). In 2011, Kozela et al. successfully demonstrated that CBD (5 mg/kg i.p.) administered at the onset of disease attenuated clinical disease, microglial activation, and T cell infiltration into the CNS in EAE, and that CBD reduced T cell proliferation in vitro.¹⁶³ CBD showed similar effects in the TMEV model, in which Mecha et al. demonstrated that CBD (5 mg/kg i.p.) administered for the first 10 days following disease onset reduced clinical disease and neuroinflammation by decreasing microglial activation and immune cell trafficking signals in the CNS.¹⁶⁴ Use of MOG_35–55-specific T cells isolated from EAE mice in vitro has also been extremely vital to determining how CBD might be affecting T cells in these and other disease models. As outlined above, in the T cell section, in vitro CBD treatment of MOG_35–55-specific T cells co-cultured with APCs with CBD suppressed IL-17A and IL-6 production, suggesting CBD suppressed TH17 development; however, production of Il10 mRNA was potentiated with CBD treatment, suggesting that CBD may have multiple suppressive mechanisms.¹⁴⁴ In vitro treatment of MOG_35–55-specific T cells with CBD induced a Treg with a CD4⁺CD25⁻LAG3⁺CD69⁺ phenotype, promoted upregulation of anergy-associated genes, such as Lag3, Erg2, and Il10, and altered the balance between STAT3 and STAT5 activation.¹⁵³ In another study, CBD administered during disease onset increased the number of functional MDSCs present within the peritoneal cavity, decreased neuroinflammation, and reduced IL-17A and IFN-γ in the serum.¹³⁷ When splenocytes from these mice were restimulated ex vivo, the CBD-treated mice had significantly decreased levels of IL-17A and IFN-γ, and increased levels of IL-10 in the supernatants.¹³⁷ Finally, a recent study using an adoptive transfer EAE model showed a reduction in neuroinflammation, demyelination, and axonal damage with CBD treatment during disease onset.¹⁶⁵ Adoptive transfer EAE is a variation of the EAE model induced by transfer of encephalitogenic T cells into naive mice, which allows experiments performed with this model to focus more on the T cell-specific mechanisms of pathogenesis in the EAE model. From the accumulation of data, it is obvious that multiple immune cell types, proinflammatory and anti-inflammatory, within the EAE model are modulated by CBD, but overall, CBD appears to downregulate proinflammatory pathways and upregulate anti-inflammatory pathways in the EAE model.

Table 5.Cannabidiol Effects in Experimental Autoimmune Encephalomyelitis

Model	Approach	Dosage/concentration	Effects	Reference
EAE in ABH	In vivo	In vivo: 0.5–25 mg/kg i.p.	No effects	²¹¹
EAE in C57BL/6	In vivo and in vitro	In vivo: 5 mg/kg i.p. in vitro: 1, 5, and 10 μM	in vivo: ↓disease severity, ↓T cell infiltration into the CNS, ↓microglial activation, ↓axonal damage in vitro: ↓T cell proliferation	^163a
TMEV in SJL/J	In vivo and in vitro	In vivo: 5 mg/kg i.p. in vitro: 1 and 5 μM	in vivo:↓disease severity, ↓leukocyte infiltration into the CNS, ↓microglial activation, ↓CCL2 (MCP-1), ↓CCL5, ↓IL-1β ↓TNF-α in vitro: ↓sVCAM-1 production from endothelial cells, ↓leukocyte adhesion, ↓CCL2 (MCP-1)	^164a
MOG_35–55-specific T cells from EAE mice	In vitro	In vitro: 0.1, 1, and 5 μM	in vitro: ↓IL-17A, ↓IL-6, ↑IL-10	^144a
MOG_35–55-specific T cells from EAE mice	In vitro	In vitro: 5 μM	in vitro:↓IL-17A, ↓IL-6, ↑IL-10, ↑EGR2, ↑CD4⁺CD25⁻CD69⁺LAG3⁺ phenotype, ↑STAT5/↓STAT3, ↓B cell activity, ↑Nfatc1, ↑Casp4, ↑Cdkn1a, ↑Icos, ↑Fas	^153a
EAE in C57BL/6	In vivo	In vivo: 5 mg/kg i.p.	in vivo: ↓disease severity, ↓leukocyte invasion, ↓demyelination, ↓TNF-α, ↓IFN-γ, ↓IL-17A	²¹²
EAE in C57BL/6	In vivo	In vivo: 10 mg/kg i.p.	in vivo: ↓disease severity, ↓FAS ligand, ↓ERK phosphorylation, ↓Caspase-3 activity, ↓Bax/↑Bcl-2, ↓p53-p21 activation, ↓apobody formation	^166a
MOG_35–55-specific T cells from EAE mice	In vitro	In vitro: 5 μM	in vitro: ↓IL-1β, ↓IL-3, ↓Xcl1 mRNA, ↓IL-12a mRNA, ↑Dusp6 mRNA, ↑Btla mRNA, ↑Lag3 mRNA, ↑Irf4 mRNA, ↑IL-10 mRNA	^143a,b
EAE in C57BL/6	In vivo	In vivo: 10 mg/kg i.p.	in vivo: ↓disease severity, ↓leukocyte infiltration, ↑PI3k/Akt/mTOR phosphorylation, ↑S6k phosphorylation, ↑BDNF expression, ↑PPAR-γ, ↓IFN-γ, ↓IL-17A, ↓JNK activity, ↓p38 MAP kinase activity	^167a
Adoptive Transfer EAE in C57BL/6	In vivo and in vitro	In vivo: 5–50 mg/kg i.p in vitro: 1, 5 & 10 μM	in vivo: ↓disease severity, ↓leukocyte invasion, ↓demyelination, ↓axonal damage, ↓microglial activation, ↓CB₂ receptor expression in CNS, ↓GPR55 receptor expression in CNS in vitro: ↓Cell viability, ↓IL-6, ↑apoptosis, ↑ROS	^165a
EAE in C57BL/6	In vivo	In vivo: 20 mg/kg i.p	in vivo: ↓disease severity, ↓leukocyte invasion, ↓IL-17A, ↓IFN-γ, ↓RORγT, ↓T-bet, ↑IL-10, ↑MDSC ex vivo: ↓IL-17A, ↓IFN-γ, ↑IL-10	^137a

In addition to its immunomodulatory effects, CBD's neuroprotective properties in the EAE model also indicate its therapeutic potential in MS. CBD has been shown to decrease the activation of proapoptotic proteins, such as caspase-3 and Bax,¹⁶⁶ and to counteract the effects of EAE on the PI3K/Akt/mTOR pathway, JNK, and p38 MAP kinases in the CNS of EAE mice.¹⁶⁷ Interestingly, the study from Giacoppo et al. found the PI3k/Akt/mTOR pathway was upregulated in neural tissues when EAE mice were treated with CBD.¹⁶⁷ However, Kozela et al.¹⁵³ observed a reduction in the activation of Akt in vitro in MOG_35–55-reactive T cells, which might suggest a differential role for CBD's effects on the PI3K/Akt/mTOR pathway in various cell types.

Despite the growing number of studies involving the neuroprotective and immunosuppressive effects of CBD, the majority of human studies involving cannabinoids and MS have been focused on the use of THC:CBD mixtures, with a particular focus on Sativex. Clinical studies that have been performed have shown that Sativex has beneficial effects on spasticity, mobility, bladder function, and pain in MS patients, and is well tolerated^{22,25,28,31,168–175}; however, there has been little focus on the neuroprotective and immunosuppressive effects of THC:CBD mixtures in MS, and so it is difficult to say at this point if the successful results observed with CBD in the animal models of MS will be observed in MS patients. For a more complete review on the effects of Sativex in MS, see Zettl et al.¹⁷⁶

Other autoimmune disease states

CBD has been shown to attenuate experimental autoimmune hepatitis,⁸⁶ experimental autoimmune myocarditis,¹²⁶ and autoimmune diabetes^123,124 in mice. There are few studies done with CBD only in human autoimmune diseases. In human patients, CBD at 20 mg/kg did not reduce clinical Crohn's disease.¹⁷⁷ However, CBD is effective at attenuating intestinal inflammation in other models of human inflammatory bowel disease,^82,96 so it is possible that CBD could be effective at higher doses. Indeed, CBD as Epidolex for epilepsy in children is being used as high as 20 mg/kg, but CBD doses as high as 300 mg/kg have been evaluated, and have not exhibited significant adverse effects.¹⁷⁸

CBD Immune Enhancement Effects

Much of the data support the fact that CBD is immune suppressive and anti-inflammatory; however, there have been a few reports over the years that CBD has produced some immune enhancing effects (Table 6). The potential for CBD, and other cannabinoids, to produce immune enhancing effects has been attributed to differences in hormetic (i.e., biphasic) responses depending on CBD concentration/dose, cell culture conditions, including serum presence and/or percent, immune stimulant, and magnitude of cellular activation in response to the immune stimulant. Indeed, studies from our laboratory and others have shown that CBD either enhanced or suppressed cytokine production (IL-2 and IFN-γ) in response to relatively low or high degree of immune stimulation, respectively.^154,179,180 The mechanism for the differential responsiveness likely involves alterations in intracellular calcium, as CBD increases intracellular calcium in mouse splenocytes regardless of the increase of intracellular calcium produced by the immune stimulant.¹⁷⁹ In addition, the differential cytokine production was correlated with nuclear expression of the NFAT transcription factor,¹⁷⁹ which is calcium responsive. Interestingly, CBD's ability to increase intracellular calcium also likely accounts for some of the other enhancing effects, including stimulation of neutrophil degranulation,¹⁸¹ chemotaxis,¹⁸² and mast cell/basophil activation.¹⁸³

Table 6.Immune Enhancement by Cannabidiol

Cell type/model	In vivo	Effect	Reference
Male human subjects	X	↑antibody response	²¹³
Rabbit neutrophils^a		↑neutrophil degranulation	^181b
Female Hartley guinea pigs	X	↑skin sensitization	²¹⁴
Female B6C3F1 mouse splenocytes		↑IL-2 production	¹⁸⁰
Mouse BV-2 microglial cells^c		↑chemotaxis	^182b
Male Swiss mouse peritoneal macrophages		↑IL-12 production	¹⁸⁷
Male Swiss mouse peritoneal macrophages	X	↑IL-12 production (stimulated ex vivo)	¹⁸⁷
Rat RBL-2H3 mast cells^c		↑mast cell/basophil activation	^183b
Female B6C3F1 and C57BL/6 mouse splenocytes		↑IL-2 and IFN-γ production	^179b
Female C57BL/6 mice	X	↑LPS-induced pulmonary inflammation	^191b
Mouse BV-2 microglial cells^c, mouse RAW264.7 macrophage cells^c, rat HAPI microglial cells^c, male C57BL/6 microglial cells		↑phagocytosis	¹⁰⁵
Female C57BL/6 splenocytes		↑IL-2 production	^154b

In addition to the ones listed in Table 6, there are a few well-studied end-points for which CBD treatment has produced opposing effects, one of which is apoptosis. As described in detail above, part of the mechanism by which CBD produces immune suppression is induction of apoptosis; however, there are a few studies in which CBD has inhibited inflammation-induced apoptosis.^118,120 Interestingly, the reports of CBD on oxidative stress are different across studies, with some articles identifying CBD as an antioxidant,^{59,118,184,185} and others reporting that CBD induces oxidative stress.^{114,115,150,151} CBD-mediated effects on IL-10 production also revealed opposing effects when compared across several studies.^{95,123,124,127,148,186–189} Effects of CBD on IL-10 could be tied to regulatory cell production (i.e., Tregs or MDSCs) or changes in T cell subpopulations.

Although it is not entirely clear why CBD produces opposing effects for many end-points, a critical part in understanding the mechanisms of CBD involves investigation of the consequences of all the changes. Let us consider two examples, the first of which was introduced in the section on cytokines (IFN-γ). We know that IFN-γ is a critical target of suppression by CBD,^{55,111,112,123,124,139,140,142,143} but there are some conditions under which CBD had no effect¹⁴³ or enhanced it.¹⁷⁹ Perhaps under some conditions, the CBD-induced enhancement of IFN-γ would increase the IFN-γ-responsive genes that attenuate T cell proliferation, as suggested by Kozela et al.¹⁴³ Thus, although CBD increased a “proinflammatory” cytokine, its consequence could be immune suppression. The second example is IL-2, which was enhanced under conditions of low-level T cell stimulation.^154,179,180 We recently showed that CBD, by producing IL-2 under some conditions, contributed to the appropriate milieu to drive Treg induction,¹⁵⁴ again demonstrating that enhancement of seemingly proinflammatory cytokines by CBD still resulted in immune suppression.

Conclusions, Challenges, and Knowledge Gaps

Considering all the studies conducted on immune responses and inflammation, the data overwhelmingly demonstrate that CBD is immune suppressive and anti-inflammatory (Fig. 1). Critical targets of suppression include cytokines such as TNF-α, IFN-γ, IL-6, IL-1β, IL-2, IL-17A, and chemokines, such as CCL-2. The overall mechanism of CBD involves direct suppression of target cells, such as effector T cells and microglial cells, through suppression of kinase cascades and various transcription factors. An example of this is CBD-induced suppression of phosphorylated p38, leading to compromised AP-1 or NF-κB activity. Direct suppression of target cells also includes induction of IκB, which could contribute to decreased NF-κB activity. The involvement of regulatory cell induction by CBD is also a major part of the mechanism by which CBD controls immune responses, and CBD has been shown to induce Tregs and MDSCs. Finally, CBD-induced apoptosis is likely an important mechanism in many target cells.

FIG. 1.Summary of CBD's mechanisms of immune suppression. Overall, CBD's immune system suppression is mediated by direct inhibition of various cell types (microglial, innate, and T cells) and induction of apoptosis and regulatory cells (Tregs and MDSCs). CBD, Cannabidiol; MDSCs, myeloid-derived suppressor cells; Treg, regulatory T cell.

It is often argued that the concentrations/doses at which CBD acts in vitro/in vivo are high. However, it should be noted that CBD is highly lipophilic and subject to first-pass metabolism after oral dosing.¹⁹⁰ In fact, we have shown that in mice at 6 h after oral CBD at 75 mg/kg/day for 3 days resulted in plasma CBD levels of ∼40 ng/mL and were not detectable by 24 h.¹⁹¹ This is ∼0.12 μM CBD, which is on the lower end of concentrations typically used in vitro to evaluate the effects of CBD as detailed in this review. On the other hand, recent data obtained in one human clinical trial that was used to support the indication of CBD as Epidiolex in epilepsy studies showed that plasma CBD levels were as high as 400 ng/mL following 20 mg/kg/day dosing for 22 days.¹⁹² This concentration is ∼1.2 μM CBD, which is a more common concentration used in vitro at which CBD effects are observed. These two studies in mice and humans^191,192 suggest that the doses and concentrations of CBD used in many of the studies in this review are appropriate. There are still limitations on our knowledge about CBD dosing and plasma levels and how those relate to immune modulation. Some of these limitations might be clarified with many of the planned clinical trials with CBD in the coming years. Specifically related to immune effects of CBD, there is a planned randomized, open-label interventional study assessing CBD and THC on immune cell activation in HIV⁺ patients.¹⁹³ Importantly, this trial will evaluate dose escalation of relatively high CBD doses compared to THC; the dose escalation for CBD will go from 45–225 mg/kg/day over a 5-week period and then maintain the highest dose for an additional 7 weeks.¹⁹³

In addition to the need for more data on CBD dosing and pharmacokinetics, this broad summary of immune and inflammatory effects of CBD revealed a number of data gaps that should be addressed. First, identification of the receptor(s) through which CBD acts in the immune system remains a critical question. An important part of this question is whether CBD-induced FAAH inhibition generates anandamide metabolites that bind to various receptors to mediate some of the immune suppressive or anti-inflammatory effects of CBD. Coupled with the observation that some of the effects of CBD can be attenuated with PPAR-γ antagonists,^92–98 the possibility exists that CBD-mediated anandamide production drives the subsequent production of (yet unidentified) metabolites that activate PPAR-γ. Another critical determination needed for many of the receptor studies is identification of the cell type(s) on which the receptors are expressed, which are mediating the CBD effects. Second, although combined cannabinoids were not a major focus of this review, it will be critical to determine the CBD contribution to immune function compromise in cannabis and/or combined pharmaceuticals such as Sativex. Third, there are still several cell types for which little data exist, notably B cells and dendritic cells. Even in the rich CBD-T cell literature, several well-established targets have not been extensively studied in T cells. In fact, there are limited data examining CBD's effects on various T cell subsets. Fourth, increasing our understanding of CBD's effects in response to a variety of immune stimuli and degrees of immune stimulation will help in interpreting effects of CBD in humans and other outbred species that are naturally exposed to a variety of pathogens. Thus, the last identified knowledge gap is the need for increased studies on the effects of CBD in human and veterinary immune responses. These include well-controlled studies considering differences with administration routes, dose, and pharmacokinetics.

Acknowledgments

The authors acknowledge ChemSpider for CBD structure. CSID:559095 (accessed 16:45, Oct 11, 2018). The authors also acknowledge Ms. Moyim Kim at Mississippi State University for help with illustrations. Research supported by Mississippi State University College of Veterinary Medicine.

Abbreviations Used

AP-1: activator protein-1
APC: antigen-presenting cell
CBD: Cannabidiol
CNS: central nervous system
DNBS: dinitrobenzene sulfonic acid
EAE: experimental autoimmune encephalomyelitis
ERK: extracellular signal-regulated kinase
FAAH: fatty acid amide hydrolase
IFN-γ: interferon-gamma
IL: interleukin
i.n.: intranasal
iNOS: inducible nitric oxide synthase
i.p.: intraperitoneal
JNK: c-jun N-terminal kinase
LPS: lipopolysaccharide
MDSCs: myeloid-derived suppressor cells
miRNA: microRNA
MOG: myelin oligodendrocyte glycoprotein
MPO: myeloperoxidase
MS: multiple sclerosis
NFAT: nuclear factor of activated T cells
NF-κB: nuclear factor-κB
PHA: phytohemagglutinin
PMA/Io: phorbol 12-myristate 13-acetate/ionomycin
PPAR-γ: peroxisome proliferator-activated receptor gamma
ROS: reactive oxygen species
sRBC: sheep red blood cell
STAT: signal transducer and activator of transcription
THC: Δ⁹-tetrahydrocannabinol
TMEV: Theiler's murine encephalomyelitis virus
TNBS: 2,4,6-trinitrobenzene sulfonic acid
TNF-α: tumor necrosis factor-alpha
Treg: regulatory T cell
TRPV1: transient receptor potential vanilloid 1
VCAM-1: vascular cell adhesion molecule-1

Author Disclosure Statement

No competing financial interests exist.

Funding Information

Funding provided by Mississippi State University College of Veterinary Medicine.

Boxed Text

Cite this article as: Nichols JM, and Kaplan BLF (2020) Immune responses regulated by cannabidiol, Cannabis and Cannabinoid Research 5:1, 12–31, DOI: 10.1089/can.2018.0073.

References

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References

1. Mechoulam R, Hanus L. Cannabidiol: an overview of some chemical and pharmacological aspects. Part I: chemical aspects. Chem Phys Lipids. 2002;121:35–43
2. Mechoulam R, Shvo Y. Hashish. I. The structure of cannabidiol. Tetrahedron. 1963;19:2073–2078
3. Hanus LO, Tchilibon S, Ponde DE, et al. Enantiomeric cannabidiol derivatives: synthesis and binding to cannabinoid receptors. Org Biomol Chem. 2005;3:1116–1123
4. Gaoni Y, Mechoulam R. Isolation, structure, and partial suntheis of an active constituent of hashish. J Am Chem Soc. 1964;86:1646–1647
5. Institute of Medicine; Joy JE, Watson SJ Jr., Benson JA. Marijuana and medicine: assessing the science base. National Academies Press: Washington, DC, 1999
6. Tanasescu R, Rog D, Constantinescu CS. A drug discovery case history of “delta-9-tetrahydrocannabinol, cannabidiol.” Expert Opin Drug Discov. 2011;6:437–452
7. Guimaraes FS, Chiaretti TM, Graeff FG, et al. Antianxiety effect of cannabidiol in the elevated plus-maze. Psychopharmacology (Berl). 1990;100:558–559
8. Zuardi AW, Cosme RA, Graeff FG, et al. Effects of ipsapirone and cannabidiol on human experimental anxiety. J Psychopharmacol. 1993;7:82–88
9. Moreira FA, Aguiar DC, Guimaraes FS. Anxiolytic-like effect of cannabidiol in the rat Vogel conflict test. Prog Neuropsychopharmacol Biol Psychiatry. 2006;30:1466–1471
10. Campos AC, Guimaraes FS. Involvement of 5HT1A receptors in the anxiolytic-like effects of cannabidiol injected into the dorsolateral periaqueductal gray of rats. Psychopharmacology (Berl). 2008;199:223–230
11. Crippa JA, Derenusson GN, Ferrari TB, et al. Neural basis of anxiolytic effects of cannabidiol (CBD) in generalized social anxiety disorder: a preliminary report. J Psychopharmacol. 2011;25:121–130
12. Bergamaschi MM, Queiroz RH, Chagas MH, et al. Cannabidiol reduces the anxiety induced by simulated public speaking in treatment-naive social phobia patients. Neuropsychopharmacology. 2011;36:1219–1226
13. Almeida V, Levin R, Peres FF, et al. Cannabidiol exhibits anxiolytic but not antipsychotic property evaluated in the social interaction test. Prog Neuropsychopharmacol Biol Psychiatry. 2013;41:30–35
14. Fogaca MV, Campos AC, Coelho LD, et al. The anxiolytic effects of cannabidiol in chronically stressed mice are mediated by the endocannabinoid system: role of neurogenesis and dendritic remodeling. Neuropharmacology. 2018;135:22–33
15. De Gregorio D, McLaughlin RJ, Posa L, et al. Cannabidiol modulates serotonergic transmission and reverses both allodynia and anxiety-like behavior in a model of neuropathic pain. Pain. 2019;160:136–150
16. Linares IM, Zuardi AW, Pereira LC, et al. Cannabidiol presents an inverted U-shaped dose-response curve in a simulated public speaking test. Braz J Psychiatry. 2019;41:9–14
17. Britch SC, Wiley JL, Yu Z, et al. Cannabidiol-Delta(9)-tetrahydrocannabinol interactions on acute pain and locomotor activity. Drug Alcohol Depend. 2017;175:187–197
18. Bornheim LM, Kim KY, Li J, et al. Effect of cannabidiol pretreatment on the kinetics of tetrahydrocannabinol metabolites in mouse brain. Drug Metab Dispos. 1995;23:825–831
19. Hlozek T, Uttl L, Kaderabek L, et al. Pharmacokinetic and behavioural profile of THC, CBD, and THC+CBD combination after pulmonary, oral, and subcutaneous administration in rats and confirmation of conversion in vivo of CBD to THC. Eur Neuropsychopharmacol. 2017;27:1223–1237
20. Nadulski T, Pragst F, Weinberg G, et al. Randomized, double-blind, placebo-controlled study about the effects of cannabidiol (CBD) on the pharmacokinetics of Delta9-tetrahydrocannabinol (THC) after oral application of THC verses standardized cannabis extract. Ther Drug Monit. 2005;27:799–810
21. Blake DR, Robson P, Ho M, et al. Preliminary assessment of the efficacy, tolerability and safety of a cannabis-based medicine (Sativex) in the treatment of pain caused by rheumatoid arthritis. Rheumatology (Oxford). 2006;45:50–52
22. Collin C, Davies P, Mutiboko IK, et al. Randomized controlled trial of cannabis-based medicine in spasticity caused by multiple sclerosis. Eur J Neurol. 2007;14:290–296
23. Russo M, Naro A, Leo A, et al. Evaluating sativex(R) in neuropathic pain management: a clinical and neurophysiological assessment in multiple sclerosis. Pain Med. 2016;17:1145–1154
24. Nurmikko TJ, Serpell MG, Hoggart B, et al. Sativex successfully treats neuropathic pain characterised by allodynia: a randomised, double-blind, placebo-controlled clinical trial. Pain. 2007;133:210–220
25. Rog DJ, Nurmikko TJ, Young CA. Oromucosal delta9-tetrahydrocannabinol/cannabidiol for neuropathic pain associated with multiple sclerosis: an uncontrolled, open-label, 2-year extension trial. Clin Ther. 2007;29:2068–2079
26. Selvarajah D, Gandhi R, Emery CJ, et al. Randomized placebo-controlled double-blind clinical trial of cannabis-based medicinal product (Sativex) in painful diabetic neuropathy: depression is a major confounding factor. Diabetes Care. 2010;33:128–130
27. Collin C, Ehler E, Waberzinek G, et al. A double-blind, randomized, placebo-controlled, parallel-group study of Sativex, in subjects with symptoms of spasticity due to multiple sclerosis. Neurol Res. 2010;32:451–459
28. Kavia RB, De Ridder D, Constantinescu CS, et al. Randomized controlled trial of Sativex to treat detrusor overactivity in multiple sclerosis. Mult Scler. 2010;16:1349–1359
29. Novotna A, Mares J, Ratcliffe S, et al. A randomized, double-blind, placebo-controlled, parallel-group, enriched-design study of nabiximols* (Sativex((R))), as add-on therapy, in subjects with refractory spasticity caused by multiple sclerosis. Eur J Neurol. 2011;18:1122–1131
30. Schoedel KA, Chen N, Hilliard A, et al. A randomized, double-blind, placebo-controlled, crossover study to evaluate the subjective abuse potential and cognitive effects of nabiximols oromucosal spray in subjects with a history of recreational cannabis use. Hum Psychopharmacol. 2011;26:224–236
31. Notcutt W, Langford R, Davies P, et al. A placebo-controlled, parallel-group, randomized withdrawal study of subjects with symptoms of spasticity due to multiple sclerosis who are receiving long-term Sativex(R) (nabiximols). Mult Scler. 2012;18:219–228
32. Johnson JR, Lossignol D, Burnell-Nugent M, et al. An open-label extension study to investigate the long-term safety and tolerability of THC/CBD oromucosal spray and oromucosal THC spray in patients with terminal cancer-related pain refractory to strong opioid analgesics. J Pain Symptom Manage. 2013;46:207–218
33. Langford RM, Mares J, Novotna A, et al. A double-blind, randomized, placebo-controlled, parallel-group study of THC/CBD oromucosal spray in combination with the existing treatment regimen, in the relief of central neuropathic pain in patients with multiple sclerosis. J Neurol. 2013;260:984–997
34. Lynch ME, Cesar-Rittenberg P, Hohmann AG. A double-blind, placebo-controlled, crossover pilot trial with extension using an oral mucosal cannabinoid extract for treatment of chemotherapy-induced neuropathic pain. J Pain Symptom Manage. 2014;47:166–173
35. Flachenecker P, Henze T, Zettl UK. Nabiximols (THC/CBD oromucosal spray, Sativex(R)) in clinical practice—results of a multicenter, non-interventional study (MOVE 2) in patients with multiple sclerosis spasticity. Eur Neurol. 2014;71:271–279
36. Marinelli L, Balestrino M, Mori L, et al. A randomised controlled cross-over double-blind pilot study protocol on THC:CBD oromucosal spray efficacy as an add-on therapy for post-stroke spasticity. BMJ Open. 2017;7:e016843.
37. Riva N, Mora G, Soraru G, et al. Safety and efficacy of nabiximols on spasticity symptoms in patients with motor neuron disease (CANALS): a multicentre, double-blind, randomised, placebo-controlled, phase 2 trial. Lancet Neurol. 2019;18:155–164
38. Porter BE, Jacobson C. Report of a parent survey of cannabidiol-enriched cannabis use in pediatric treatment-resistant epilepsy. Epilepsy Behav. 2013;29:574–577
39. Hussain SA, Zhou R, Jacobson C, et al. Perceived efficacy of cannabidiol-enriched cannabis extracts for treatment of pediatric epilepsy: a potential role for infantile spasms and Lennox-Gastaut syndrome. Epilepsy Behav. 2015;47:138–141
40. Devinsky O, Marsh E, Friedman D, et al. Cannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trial. Lancet Neurol. 2016;15:270–278
41. Sands TT, Rahdari S, Oldham MS, et al. Long-term safety, tolerability, and efficacy of cannabidiol in children with refractory epilepsy: results from an expanded access program in the US. CNS Drugs. 2019;33:47–60
42. Thiele EA, Marsh ED, French JA, et al. Cannabidiol in patients with seizures associated with Lennox-Gastaut syndrome (GWPCARE4): a randomised, double-blind, placebo-controlled phase 3 trial. Lancet. 2018;391:1085–1096
43. Hess EJ, Moody KA, Geffrey AL, et al. Cannabidiol as a new treatment for drug-resistant epilepsy in tuberous sclerosis complex. Epilepsia. 2016;57:1617–1624
44. Serra I, Scheldeman C, Bazelot M, et al. Cannabidiol modulates phosphorylated rpS6 signalling in a zebrafish model of Tuberous Sclerosis Complex. Behav Brain Res. 2019;363:135–144
45. McGuire P, Robson P, Cubala WJ, et al. Cannabidiol (CBD) as an adjunctive therapy in schizophrenia: a multicenter randomized controlled trial. Am J Psychiatry. 2018;175:225–231
46. Reithmeier D, Tang-Wai R, Seifert B, et al. The protocol for the Cannabidiol in children with refractory epileptic encephalopathy (CARE-E) study: a phase 1 dosage escalation study. BMC Pediatr. 2018;18:221.
47. Corroon J, Kight R. Regulatory status of cannabidiol in the United States: a perspective. Cannabis Cannabinoid Res. 2018;3:190–194
48. National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Board on Population Health and Public Health Practice; Committee on the Health Effects of Marijuana: An Evidence Review and Research Agenda. The health effects of cannabis and cannabinoids: the current state of evidence and recommendataions for research. National Academies Press, Washington, DC, 2017
49. Substance Abuse and Mental Health Services Administration. Key substance use and mental health indicators in the United States: results from the 2016 National Survey on Drug Use and Health (HHS Publication No. SMA 17–5044, NSDUH Series H-52). 2017. Available at: https://www.samhsa.gov/data/data-we-collect/nsduh-national-survey-drug-use-and-health (accessed August25, 2019)
50. Hoffenberg EJ, McWilliams S, Mikulich-Gilbertson S, et al. Cannabis oil use by adolescents and young adults with inflammatory bowel disease. J Pediatr Gastroenterol Nutr. 2019;68:348–352
51. Armour M, Sinclair J, Chalmers KJ, et al. Self-management strategies amongst Australian women with endometriosis: a national online survey. BMC Complement Altern Med. 2019;19:17.
52. Sekar K, Pack A. Epidiolex as adjunct therapy for treatment of refractory epilepsy: a comprehensive review with a focus on adverse effects. F1000Res. 2019;8:F1000.
53. Matsuda LA, Lolait SJ, Brownstein MJ, et al. Structure of a cannabinoid receptor and functional expression of the cloned cDNA. Nature. 1990;346:561–564
54. Munro S, Thomas KL, Abu-Shaar M. Molecular characterization of a peripheral receptor for cannabinoids. Nature. 1993;365:61–65
55. Kaplan BL, Springs AE, Kaminski NE. The profile of immune modulation by cannabidiol (CBD) involves deregulation of nuclear factor of activated T cells (NFAT). Biochem Pharmacol. 2008;76:726–737
56. Thapa D, Cairns EA, Szczesniak AM, et al. The cannabinoids delta(8)THC, CBD, and HU-308 act via distinct receptors to reduce corneal pain and inflammation. Cannabis Cannabinoid Res. 2018;3:11–20
57. Khuja I, Yekhtin Z, Or R, et al. Cannabinoids reduce inflammation but inhibit lymphocyte recovery in murine models of bone marrow transplantation. Int J Mol Sci. 2019;20:E668.
58. de Filippis D, Iuvone T, d'amico A, et al. Effect of cannabidiol on sepsis-induced motility disturbances in mice: involvement of CB receptors and fatty acid amide hydrolase. Neurogastroenterol Motil. 2008;20:919–927
59. Pazos MR, Mohammed N, Lafuente H, et al. Mechanisms of cannabidiol neuroprotection in hypoxic-ischemic newborn pigs: role of 5HT(1A) and CB2 receptors. Neuropharmacology. 2013;71:282–291
60. Vuolo F, Abreu SC, Michels M, et al. Cannabidiol reduces airway inflammation and fibrosis in experimental allergic asthma. Eur J Pharmacol. 2019;843:251–259
61. Laprairie RB, Bagher AM, Kelly ME, et al. Cannabidiol is a negative allosteric modulator of the cannabinoid CB1 receptor. Br J Pharmacol. 2015;172:4790–4805
62. Tham M, Yilmaz O, Alaverdashvili M, et al. Allosteric and orthosteric pharmacology of cannabidiol and cannabidiol-dimethylheptyl at the type 1 and type 2 cannabinoid receptors. Br J Pharmacol. 2019;176:1455–1469
63. Navarro G, Reyes-Resina I, Rivas-Santisteban R, et al. Cannabidiol skews biased agonism at cannabinoid CB1 and CB2 receptors with smaller effect in CB1-CB2 heteroreceptor complexes. Biochem Pharmacol. 2018;157:148–158
64. Martinez-Pinilla E, Varani K, Reyes-Resina I, et al. Binding and signaling studies disclose a potential allosteric site for cannabidiol in cannabinoid CB2 receptors. Front Pharmacol. 2017;8:744.
65. Bisogno T, Hanus L, De Petrocellis L, et al. Molecular targets for cannabidiol and its synthetic analogues: effect on vanilloid VR1 receptors and on the cellular uptake and enzymatic hydrolysis of anandamide. Br J Pharmacol. 2001;134:845–852
66. De Petrocellis L, Ligresti A, Moriello AS, et al. Effects of cannabinoids and cannabinoid-enriched Cannabis extracts on TRP channels and endocannabinoid metabolic enzymes. Br J Pharmacol. 2011;163:1479–1494
67. Elmes MW, Kaczocha M, Berger WT, et al. Fatty acid-binding proteins (FABPs) are intracellular carriers for Delta9-tetrahydrocannabinol (THC) and cannabidiol (CBD). J Biol Chem. 2015;290:8711–8721
68. Devane WA, Hanus L, Breuer A, et al. Isolation and structure of a brain constituent that binds to the cannabinoid receptor. Science. 1992;258:1946–1949
69. Facci L, Dal Toso R, Romanello S, et al. Mast cells express a peripheral cannabinoid receptor with differential sensitivity to anandamide and palmitoylethanolamide. Proc Natl Acad Sci U S A. 1995;92:3376–3380
70. Alhouayek M, Muccioli GG. COX-2-derived endocannabinoid metabolites as novel inflammatory mediators. Trends Pharmacol Sci. 2014;35:284–292
71. Zelasko S, Arnold WR, Das A. Endocannabinoid metabolism by cytochrome P450 monooxygenases. Prostaglandins Other Lipid Mediat. 2015;116–117:112–123
72. Alhamoruni A, Lee AC, Wright KL, et al. Pharmacological effects of cannabinoids on the Caco-2 cell culture model of intestinal permeability. J Pharmacol Exp Ther. 2010;335:92–102
73. Alhamoruni A, Wright KL, Larvin M, et al. Cannabinoids mediate opposing effects on inflammation-induced intestinal permeability. Br J Pharmacol. 2012;165:2598–2610
74. Stanley CP, Hind WH, Tufarelli C, et al. Cannabidiol causes endothelium-dependent vasorelaxation of human mesenteric arteries via CB1 activation. Cardiovasc Res. 2015;107:568–578
75. Campos AC, Ortega Z, Palazuelos J, et al. The anxiolytic effect of cannabidiol on chronically stressed mice depends on hippocampal neurogenesis: involvement of the endocannabinoid system. Int J Neuropsychopharmacol. 2013;16:1407–1419
76. Sartim AG, Guimaraes FS, Joca SR. Antidepressant-like effect of cannabidiol injection into the ventral medial prefrontal cortex-Possible involvement of 5-HT1A and CB1 receptors. Behav Brain Res. 2016;303:218–227
77. Hwang YS, Kim YJ, Kim MO, et al. Cannabidiol upregulates melanogenesis through CB1 dependent pathway by activating p38 MAPK and p42/44 MAPK. Chem Biol Interact. 2017;273:107–114
78. Capasso R, Borrelli F, Aviello G, et al. Cannabidiol, extracted from Cannabis sativa, selectively inhibits inflammatory hypermotility in mice. Br J Pharmacol. 2008;154:1001–1008
79. Libro R, Scionti D, Diomede F, et al. Cannabidiol modulates the immunophenotype and inhibits the activation of the inflammasome in human gingival mesenchymal stem cells. Front Physiol. 2016;7:559.
80. McKallip RJ, Jia W, Schlomer J, et al. Cannabidiol-induced apoptosis in human leukemia cells: a novel role of cannabidiol in the regulation of p22phox and Nox4 expression. Mol Pharmacol. 2006;70:897–908
81. Toth CC, Jedrzejewski NM, Ellis CL, et al. Cannabinoid-mediated modulation of neuropathic pain and microglial accumulation in a model of murine type I diabetic peripheral neuropathic pain. Mol Pain. 2010;6:16.
82. Couch DG, Tasker C, Theophilidou E, et al. Cannabidiol and palmitoylethanolamide are anti-inflammatory in the acutely inflamed human colon. Clin Sci (Lond). 2017;131:2611–2626
83. Philpott HT, O'Brien M, McDougall JJ. Attenuation of early phase inflammation by cannabidiol prevents pain and nerve damage in rat osteoarthritis. Pain. 2017;158:2442–2451
84. Petrosino S, Verde R, Vaia M, et al. Anti-inflammatory properties of cannabidiol, a nonpsychotropic cannabinoid, in experimental allergic contact dermatitis. J Pharmacol Exp Ther. 2018;365:652–663
85. Iannotti FA, Hill CL, Leo A, et al. Nonpsychotropic plant cannabinoids, cannabidivarin (CBDV) and cannabidiol (CBD), activate and desensitize transient receptor potential vanilloid 1 (TRPV1) channels in vitro: potential for the treatment of neuronal hyperexcitability. ACS Chem Neurosci. 2014;5:1131–1141
86. Hegde VL, Nagarkatti PS, Nagarkatti M. Role of myeloid-derived suppressor cells in amelioration of experimental autoimmune hepatitis following activation of TRPV1 receptors by cannabidiol. PLoS One. 2011;6:e18281.
87. Costa B, Giagnoni G, Franke C, et al. Vanilloid TRPV1 receptor mediates the antihyperalgesic effect of the nonpsychoactive cannabinoid, cannabidiol, in a rat model of acute inflammation. Br J Pharmacol. 2004;143:247–250
88. Costa B, Trovato AE, Comelli F, et al. The non-psychoactive cannabis constituent cannabidiol is an orally effective therapeutic agent in rat chronic inflammatory and neuropathic pain. Eur J Pharmacol. 2007;556:75–83
89. Carrier EJ, Auchampach JA, Hillard CJ. Inhibition of an equilibrative nucleoside transporter by cannabidiol: a mechanism of cannabinoid immunosuppression. Proc Natl Acad Sci U S A. 2006;103:7895–7900
90. Castillo A, Tolon MR, Fernandez-Ruiz J, et al. The neuroprotective effect of cannabidiol in an in vitro model of newborn hypoxic-ischemic brain damage in mice is mediated by CB(2) and adenosine receptors. Neurobiol Dis. 2010;37:434–440
91. Liou GI, Auchampach JA, Hillard CJ, et al. Mediation of cannabidiol anti-inflammation in the retina by equilibrative nucleoside transporter and A2A adenosine receptor. Invest Ophthalmol Vis Sci. 2008;49:5526–5531
92. Esposito G, Scuderi C, Valenza M, et al. Cannabidiol reduces Abeta-induced neuroinflammation and promotes hippocampal neurogenesis through PPARgamma involvement. PLoS One. 2011;6:e28668.
93. Ramer R, Heinemann K, Merkord J, et al. COX-2 and PPAR-gamma confer cannabidiol-induced apoptosis of human lung cancer cells. Mol Cancer Ther. 2013;12:69–82
94. Scuderi C, Steardo L, Esposito G. Cannabidiol promotes amyloid precursor protein ubiquitination and reduction of beta amyloid expression in SHSY5YAPP+ cells through PPARgamma involvement. Phytother Res. 2014;28:1007–1013
95. Borrelli F, Aviello G, Romano B, et al. Cannabidiol, a safe and non-psychotropic ingredient of the marijuana plant Cannabis sativa, is protective in a murine model of colitis. J Mol Med (Berl). 2009;87:1111–1121
96. De Filippis D, Esposito G, Cirillo C, et al. Cannabidiol reduces intestinal inflammation through the control of neuroimmune axis. PLoS One. 2011;6:e28159.
97. Sonego AB, Prado DS, Vale GT, et al. Cannabidiol prevents haloperidol-induced vacuos chewing movements and inflammatory changes in mice via PPARgamma receptors. Brain Behav Immun. 2018;74:241–251
98. Hind WH, England TJ, O'Sullivan SE. Cannabidiol protects an in vitro model of the blood-brain barrier from oxygen-glucose deprivation via PPARgamma and 5-HT1A receptors. Br J Pharmacol. 2016;173:815–825
99. Russo EB, Burnett A, Hall B, et al. Agonistic properties of cannabidiol at 5-HT1a receptors. Neurochem Res. 2005;30:1037–1043
100. Abdouh M, Storring JM, Riad M, et al. Transcriptional mechanisms for induction of 5-HT1A receptor mRNA and protein in activated B and T lymphocytes. J Biol Chem. 2001;276:4382–4388
101. Fajardo O, Galeno J, Urbina M, et al. Serotonin, serotonin 5-HT(1A) receptors and dopamine in blood peripheral lymphocytes of major depression patients. Int Immunopharmacol. 2003;3:1345–1352
102. Xu J, Zhang G, Cheng Y, et al. Hypomethylation of the HTR1A promoter region and high expression of HTR1A in the peripheral blood lymphocytes of patients with systemic lupus erythematosus. Lupus. 2011;20:678–689
103. Hernandez-Torres G, Enriquez-Palacios E, Mecha M, et al. Development of a fluorescent bodipy probe for visualization of the serotonin 5-HT1A receptor in native cells of the immune system. Bioconjug Chem. 2018;29:2021–2027
104. Qin N, Neeper MP, Liu Y, et al. TRPV2 is activated by cannabidiol and mediates CGRP release in cultured rat dorsal root ganglion neurons. J Neurosci. 2008;28:6231–6238
105. Hassan S, Eldeeb K, Millns PJ, et al. Cannabidiol enhances microglial phagocytosis via transient receptor potential (TRP) channel activation. Br J Pharmacol. 2014;171:2426–2439
106. De Petrocellis L, Orlando P, Moriello AS, et al. Cannabinoid actions at TRPV channels: effects on TRPV3 and TRPV4 and their potential relevance to gastrointestinal inflammation. Acta Physiol (Oxf). 2012;204:255–266
107. De Petrocellis L, Vellani V, Schiano-Moriello A, et al. Plant-derived cannabinoids modulate the activity of transient receptor potential channels of ankyrin type-1 and melastatin type-8. J Pharmacol Exp Ther. 2008;325:1007–1015
108. Kathmann M, Flau K, Redmer A, et al. Cannabidiol is an allosteric modulator at mu- and delta-opioid receptors. Naunyn Schmiedebergs Arch Pharmacol. 2006;372:354–361
109. Ryberg E, Larsson N, Sjogren S, et al. The orphan receptor GPR55 is a novel cannabinoid receptor. Br J Pharmacol. 2007;152:1092–1101
110. Chiurchiu V, Lanuti M, De Bardi M, et al. The differential characterization of GPR55 receptor in human peripheral blood reveals a distinctive expression in monocytes and NK cells and a proinflammatory role in these innate cells. Int Immunol. 2015;27:153–160
111. Watzl B, Scuderi P, Watson RR. Marijuana components stimulate human peripheral blood mononuclear cell secretion of interferon-gamma and suppress interleukin-1 alpha in vitro. Int J Immunopharmacol. 1991;13:1091–1097
112. Watzl B, Scuderi P, Watson RR. Influence of marijuana components (THC and CBD) on human mononuclear cell cytokine secretion in vitro. Adv Exp Med Biol. 1991;288:63–70
113. Gallily R, Even-Chena T, Katzavian G, et al. Gamma-irradiation enhances apoptosis induced by cannabidiol, a non-psychotropic cannabinoid, in cultured HL-60 myeloblastic leukemia cells. Leuk Lymphoma. 2003;44:1767–1773
114. Wu HY, Chang AC, Wang CC, et al. Cannabidiol induced a contrasting pro-apoptotic effect between freshly isolated and precultured human monocytes. Toxicol Appl Pharmacol. 2010;246:141–147
115. Wu HY, Huang CH, Lin YH, et al. Cannabidiol induced apoptosis in human monocytes through mitochondrial permeability transition pore-mediated ROS production. Free Radic Biol Med. 2018;124:311–318
116. Coffey RG, Yamamoto Y, Snella E, et al. Tetrahydrocannabinol inhibition of macrophage nitric oxide production. Biochem Pharmacol. 1996;52:743–751
117. Esposito G, Scuderi C, Savani C, et al. Cannabidiol in vivo blunts beta-amyloid induced neuroinflammation by suppressing IL-1beta and iNOS expression. Br J Pharmacol. 2007;151:1272–1279
118. Mukhopadhyay P, Rajesh M, Horvath B, et al. Cannabidiol protects against hepatic ischemia/reperfusion injury by attenuating inflammatory signaling and response, oxidative/nitrative stress, and cell death. Free Radic Biol Med. 2011;50:1368–1381
119. Rajesh M, Mukhopadhyay P, Batkai S, et al. Cannabidiol attenuates high glucose-induced endothelial cell inflammatory response and barrier disruption. Am J Physiol Heart Circ Physiol. 2007;293:H610–619
120. Rajesh M, Mukhopadhyay P, Batkai S, et al. Cannabidiol attenuates cardiac dysfunction, oxidative stress, fibrosis, and inflammatory and cell death signaling pathways in diabetic cardiomyopathy. J Am Coll Cardiol. 2010;56:2115–2125
121. Ruiz-Valdepenas L, Martinez-Orgado JA, Benito C, et al. Cannabidiol reduces lipopolysaccharide-induced vascular changes and inflammation in the mouse brain: an intravital microscopy study. J Neuroinflammation. 2011;8:5.
122. Kleinert H, Pautz A, Linker K, et al. Regulation of the expression of inducible nitric oxide synthase. Eur J Pharmacol. 2004;500:255–266
123. Weiss L, Zeira M, Reich S, et al. Cannabidiol lowers incidence of diabetes in non-obese diabetic mice. Autoimmunity. 2006;39:143–151
124. Weiss L, Zeira M, Reich S, et al. Cannabidiol arrests onset of autoimmune diabetes in NOD mice. Neuropharmacology. 2008;54:244–249
125. Ribeiro A, Ferraz-de-Paula V, Pinheiro ML, et al. Cannabidiol, a non-psychotropic plant-derived cannabinoid, decreases inflammation in a murine model of acute lung injury: role for the adenosine A(2A) receptor. Eur J Pharmacol. 2012;678:78–85
126. Lee WS, Erdelyi K, Matyas C, et al. Cannabidiol limits T cell-mediated chronic autoimmune myocarditis: implications to autoimmune disorders and organ transplantation. Mol Med. 2016;22:136–146
127. Vuolo F, Petronilho F, Sonai B, et al. Evaluation of serum cytokines levels and the role of cannabidiol treatment in animal model of asthma. Mediators Inflamm. 2015;2015:538670.
128. Li K, Feng JY, Li YY, et al. Anti-inflammatory role of cannabidiol and O-1602 in cerulein-induced acute pancreatitis in mice. Pancreas. 2013;42:123–129
129. Hayakawa K, Mishima K, Nozako M, et al. Delayed treatment with cannabidiol has a cerebroprotective action via a cannabinoid receptor-independent myeloperoxidase-inhibiting mechanism. J Neurochem. 2007;102:1488–1496
130. Jamontt JM, Molleman A, Pertwee RG, et al. The effects of Delta-tetrahydrocannabinol and cannabidiol alone and in combination on damage, inflammation and in vitro motility disturbances in rat colitis. Br J Pharmacol. 2010;160:712–723
131. Pagano E, Capasso R, Piscitelli F, et al. An orally active cannabis extract with high content in cannabidiol attenuates chemically-induced intestinal inflammation and hypermotility in the mouse. Front Pharmacol. 2016;7:341.
132. Ribeiro A, Almeida VI, Costola-de-Souza C, et al. Cannabidiol improves lung function and inflammation in mice submitted to LPS-induced acute lung injury. Immunopharmacol Immunotoxicol. 2015;37:35–41
133. Henriquez JE, Crawford RB, Kaminski NE. Suppression of CpG-ODN-mediated IFNalpha and TNFalpha response in human plasmacytoid dendritic cells (pDC) by cannabinoid receptor 2 (CB2)-specific agonists. Toxicol Appl Pharmacol. 2019;369:82–89
134. Henriquez JE, Rizzo MD, Schulz MA, et al. Delta9-tetrahydrocannabinol suppresses secretion of IFNalpha by plasmacytoid dendritic cells from healthy and HIV-infected individuals. J Acquir Immune Defic Syndr. 2017;75:588–596
135. Prechtel AT, Steinkasserer A. CD83: an update on functions and prospects of the maturation marker of dendritic cells. Arch Dermatol Res. 2007;299:59–69
136. Hegde VL, Singh UP, Nagarkatti PS, et al. Critical role of mast cells and peroxisome proliferator-activated receptor gamma in the induction of myeloid-derived suppressor cells by marijuana cannabidiol in vivo. J Immunol. 2015;194:5211–5222
137. Elliott DM, Singh N, Nagarkatti M, et al. Cannabidiol attenuates experimental autoimmune encephalomyelitis model of multiple sclerosis through induction of myeloid-derived suppressor cells. Front Immunol. 2018;9:1782.
138. Cushman P., Jr. Cannabinols and the rosette forming properties of lymphocytes in vitro. Life Sci. 1976;19:875–885
139. Malfait AM, Gallily R, Sumariwalla PF, et al. The nonpsychoactive cannabis constituent cannabidiol is an oral anti-arthritic therapeutic in murine collagen-induced arthritis. Proc Natl Acad Sci U S A. 2000;97:9561–9566
140. Jan TR, Su ST, Wu HY, et al. Suppressive effects of cannabidiol on antigen-specific antibody production and functional activity of splenocytes in ovalbumin-sensitized BALB/c mice. Int Immunopharmacol. 2007;7:773–780
141. Karmaus PW, Chen W, Kaplan BL, et al. Delta9-tetrahydrocannabinol suppresses cytotoxic T lymphocyte function independent of CB1 and CB2, disrupting early activation events. J Neuroimmune Pharmacol. 2012;7:843–855
142. Jenny M, Santer E, Pirich E, et al. Delta9-tetrahydrocannabinol and cannabidiol modulate mitogen-induced tryptophan degradation and neopterin formation in peripheral blood mononuclear cells in vitro. J Neuroimmunol. 2009;207:75–82
143. Kozela E, Juknat A, Gao F, et al. Pathways and gene networks mediating the regulatory effects of cannabidiol, a nonpsychoactive cannabinoid, in autoimmune T cells. J Neuroinflammation. 2016;13:136.
144. Kozela E, Juknat A, Kaushansky N, et al. Cannabinoids decrease the th17 inflammatory autoimmune phenotype. J Neuroimmune Pharmacol. 2013;8:1265–1276
145. Zhou L, Ivanov II, Spolski R, et al. IL-6 programs T(H)-17 cell differentiation by promoting sequential engagement of the IL-21 and IL-23 pathways. Nat Immunol. 2007;8:967–974
146. Zgair A, Lee JB, Wong JCM, et al. Oral administration of cannabis with lipids leads to high levels of cannabinoids in the intestinal lymphatic system and prominent immunomodulation. Sci Rep. 2017;7:14542.
147. Kozela E, Pietr M, Juknat A, et al. Cannabinoids Delta(9)-tetrahydrocannabinol and cannabidiol differentially inhibit the lipopolysaccharide-activated NF-kappaB and interferon-beta/STAT proinflammatory pathways in BV-2 microglial cells. J Biol Chem. 2010;285:1616–1626
148. Rajan TS, Giacoppo S, Iori R, et al. Anti-inflammatory and antioxidant effects of a combination of cannabidiol and moringin in LPS-stimulated macrophages. Fitoterapia. 2016;112:104–115
149. Khaksar S, Bigdeli MR. Correlation between cannabidiol-induced reduction of infarct volume and inflammatory factors expression in ischemic stroke model. Basic Clin Neurosci. 2017;8:139–146
150. Lee CY, Wey SP, Liao MH, et al. A comparative study on cannabidiol-induced apoptosis in murine thymocytes and EL-4 thymoma cells. Int Immunopharmacol. 2008;8:732–740
151. Wu HY, Chu RM, Wang CC, et al. Cannabidiol-induced apoptosis in primary lymphocytes is associated with oxidative stress-dependent activation of caspase-8. Toxicol Appl Pharmacol. 2008;226:260–270
152. Baban B, Hoda N, Malik A, et al. Impact of cannabidiol treatment on regulatory T-17 cells and neutrophil polarization in acute kidney injury. Am J Physiol Renal Physiol. 2018;315:F1149–F1158
153. Kozela E, Juknat A, Kaushansky N, et al. Cannabidiol, a non-psychoactive cannabinoid, leads to EGR2-dependent anergy in activated encephalitogenic T cells. J Neuroinflammation. 2015;12:52.
154. Dhital S, Stokes JV, Park N, et al. Cannabidiol (CBD) induces functional Tregs in response to low-level T cell activation. Cell Immunol. 2017;312:25–34
155. Zimmerman S, Zimmerman AM, Cameron IL, et al. delta1-tetrahydrocannabinol, cannabidiol and cannabinol effects on the immune response of mice. Pharmacology. 1977;15:10–23
156. Wu HY, Goble K, Mecha M, et al. Cannabidiol-induced apoptosis in murine microglial cells through lipid raft. Glia. 2012;60:1182–1190
157. Rimmerman N, Juknat A, Kozela E, et al. The non-psychoactive plant cannabinoid, cannabidiol affects cholesterol metabolism-related genes in microglial cells. Cell Mol Neurobiol. 2011;31:921–930
158. Juknat A, Rimmerman N, Levy R, et al. Cannabidiol affects the expression of genes involved in zinc homeostasis in BV-2 microglial cells. Neurochem Int. 2012;61:923–930
159. Juknat A, Pietr M, Kozela E, et al. Differential transcriptional profiles mediated by exposure to the cannabinoids cannabidiol and Delta9-tetrahydrocannabinol in BV-2 microglial cells. Br J Pharmacol. 2012;165:2512–2528
160. Watanabe K, Kayano Y, Matsunaga T, et al. Inhibition of anandamide amidase activity in mouse brain microsomes by cannabinoids. Biol Pharm Bull. 1996;19:1109–1111
161. Juknat A, Gao F, Coppola G, et al. miRNA expression profiles and molecular networks in resting and LPS-activated BV-2 microglia-effect of cannabinoids. PLoS One. 2019;14:e0212039.
162. Dendrou CA, Fugger L, Friese MA. Immunopathology of multiple sclerosis. Nat Rev Immunol. 2015;15:545–558
163. Kozela E, Lev N, Kaushansky N, et al. Cannabidiol inhibits pathogenic T cells, decreases spinal microglial activation and ameliorates multiple sclerosis-like disease in C57BL/6 mice. Br J Pharmacol. 2011;163:1507–1519
164. Mecha M, Feliu A, Inigo PM, et al. Cannabidiol provides long-lasting protection against the deleterious effects of inflammation in a viral model of multiple sclerosis: a role for A2A receptors. Neurobiol Dis. 2013;59:141–150
165. Gonzalez-Garcia C, Torres IM, Garcia-Hernandez R, et al. Mechanisms of action of cannabidiol in adoptively transferred experimental autoimmune encephalomyelitis. Exp Neurol. 2017;298:57–67
166. Giacoppo S, Soundara Rajan T, Galuppo M, et al. Purified Cannabidiol, the main non-psychotropic component of Cannabis sativa, alone, counteracts neuronal apoptosis in experimental multiple sclerosis. Eur Rev Med Pharmacol Sci. 2015;19:4906–4919
167. Giacoppo S, Pollastro F, Grassi G, et al. Target regulation of PI3K/Akt/mTOR pathway by cannabidiol in treatment of experimental multiple sclerosis. Fitoterapia. 2017;116:77–84
168. Coghe G, Pau M, Corona F, et al. Walking improvements with nabiximols in patients with multiple sclerosis. J Neurol. 2015;262:2472–2477
169. Lorente Fernandez L, Monte Boquet E, Perez-Miralles F, et al. Clinical experiences with cannabinoids in spasticity management in multiple sclerosis. Neurologia. 2014;29:257–260
170. Messina S, Solaro C, Righini I, et al. Sativex in resistant multiple sclerosis spasticity: discontinuation study in a large population of Italian patients (SA.FE. study). PLoS One. 2017;12:e0180651.
171. Patti F, Messina S, Solaro C, et al. Efficacy and safety of cannabinoid oromucosal spray for multiple sclerosis spasticity. J Neurol Neurosurg Psychiatry. 2016;87:944–951
172. Rog DJ, Nurmikko TJ, Friede T, et al. Randomized, controlled trial of cannabis-based medicine in central pain in multiple sclerosis. Neurology. 2005;65:812–819
173. Vaney C, Heinzel-Gutenbrunner M, Jobin P, et al. Efficacy, safety and tolerability of an orally administered cannabis extract in the treatment of spasticity in patients with multiple sclerosis: a randomized, double-blind, placebo-controlled, crossover study. Mult Scler. 2004;10:417–424
174. Wade DT, Makela P, Robson P, et al. Do cannabis-based medicinal extracts have general or specific effects on symptoms in multiple sclerosis? A double-blind, randomized, placebo-controlled study on 160 patients. Mult Scler. 2004;10:434–441
175. Zajicek J, Fox P, Sanders H, et al. Cannabinoids for treatment of spasticity and other symptoms related to multiple sclerosis (CAMS study): multicentre randomised placebo-controlled trial. Lancet. 2003;362:1517–1526
176. Zettl UK, Rommer P, Hipp P, et al. Evidence for the efficacy and effectiveness of THC-CBD oromucosal spray in symptom management of patients with spasticity due to multiple sclerosis. Ther Adv Neurol Disord. 2016;9:9–30
177. Naftali T, Mechulam R, Marii A, et al. Low-dose cannabidiol is safe but not effective in the treatment for crohn's disease, a randomized controlled trial. Dig Dis Sci. 2017;62:1615–1620
178. Leo A, Russo E, Elia M. Cannabidiol and epilepsy: rationale and therapeutic potential. Pharmacol Res. 2016;107:85–92
179. Chen W, Kaplan BL, Pike ST, et al. Magnitude of stimulation dictates the cannabinoid-mediated differential T cell response to HIVgp120. J Leukoc Biol. 2012;92:1093–1102
180. Jan TR, Kaminski NE. Role of mitogen-activated protein kinases in the differential regulation of interleukin-2 by cannabinol. J Leukoc Biol. 2001;69:841–849
181. Naccache PH, Volpi M, Becker EL, et al. Cannabinoid induced degranulation of rabbit neutrophils. Biochem Biophys Res Commun. 1982;106:1286–1290
182. Walter L, Franklin A, Witting A, et al. Nonpsychotropic cannabinoid receptors regulate microglial cell migration. J Neurosci. 2003;23:1398–1405
183. Giudice ED, Rinaldi L, Passarotto M, et al. Cannabidiol, unlike synthetic cannabinoids, triggers activation of RBL-2H3 mast cells. J Leukoc Biol. 2007;81:1512–1522
184. Cassol OJ Jr., Comim CM, Silva BR, et al. Treatment with cannabidiol reverses oxidative stress parameters, cognitive impairment and mortality in rats submitted to sepsis by cecal ligation and puncture. Brain Res. 2010;1348:128–138
185. Wang Y, Mukhopadhyay P, Cao Z, et al. Cannabidiol attenuates alcohol-induced liver steatosis, metabolic dysregulation, inflammation and neutrophil-mediated injury. Sci Rep. 2017;7:12064.
186. Srivastava MD, Srivastava BI, Brouhard B. Delta9 tetrahydrocannabinol and cannabidiol alter cytokine production by human immune cells. Immunopharmacology. 1998;40:179–185
187. Sacerdote P, Martucci C, Vaccani A, et al. The nonpsychoactive component of marijuana cannabidiol modulates chemotaxis and IL-10 and IL-12 production of murine macrophages both in vivo and in vitro. J Neuroimmunol. 2005;159:97–105
188. Liu DZ, Hu CM, Huang CH, et al. Cannabidiol attenuates delayed-type hypersensitivity reactions via suppressing T-cell and macrophage reactivity. Acta Pharmacol Sin. 2010;31:1611–1617
189. Li H, Kong W, Chambers CR, et al. The non-psychoactive phytocannabinoid cannabidiol (CBD) attenuates pro-inflammatory mediators, T cell infiltration, and thermal sensitivity following spinal cord injury in mice. Cell Immunol. 2018;329:1–9
190. Samara E, Bialer M, Mechoulam R. Pharmacokinetics of cannabidiol in dogs. Drug Metab Dispos. 1988;16:469–472
191. Karmaus PW, Wagner JG, Harkema JR, et al. Cannabidiol (CBD) enhances lipopolysaccharide (LPS)-induced pulmonary inflammation in C57BL/6 mice. J Immunotoxicol. 2013;10:321–328
192. Devinsky O, Patel AD, Thiele EA, et al. Randomized, dose-ranging safety trial of cannabidiol in Dravet syndrome. Neurology. 2018;90:e1204–e1211
193. Costiniuk CT, Saneei Z, Routy JP, et al. Oral cannabinoids in people living with HIV on effective antiretroviral therapy: CTN PT028-study protocol for a pilot randomised trial to assess safety, tolerability and effect on immune activation. BMJ Open. 2019;9:e024793.
194. Fonseca BM, Correia-da-Silva G, Teixeira NA. Cannabinoid-induced cell death in endometrial cancer cells: involvement of TRPV1 receptors in apoptosis. J Physiol Biochem. 2018;74:261–272
195. McHugh D, Tanner C, Mechoulam R, et al. Inhibition of human neutrophil chemotaxis by endogenous cannabinoids and phytocannabinoids: evidence for a site distinct from CB1 and CB2. Mol Pharmacol. 2008;73:441–450
196. Kaplan BL, Rockwell CE, Kaminski NE. Evidence for cannabinoid receptor-dependent and -independent mechanisms of action in leukocytes. J Pharmacol Exp Ther. 2003;306:1077–1085
197. Lafaye G, Desterke C, Marulaz L, et al. Cannabidiol affects circadian clock core complex and its regulation in microglia cells. Addict Biol. 2018. [Epub ahead of print]; DOI: 10.1111/adb.12660
198. Lodzki M, Godin B, Rakou L, et al. Cannabidiol-transdermal delivery and anti-inflammatory effect in a murine model. J Control Release. 2003;93:377–387
199. Costa B, Colleoni M, Conti S, et al. Oral anti-inflammatory activity of cannabidiol, a non-psychoactive constituent of cannabis, in acute carrageenan-induced inflammation in the rat paw. Naunyn Schmiedebergs Arch Pharmacol. 2004;369:294–299
200. Durst R, Danenberg H, Gallily R, et al. Cannabidiol, a nonpsychoactive Cannabis constituent, protects against myocardial ischemic reperfusion injury. Am J Physiol Heart Circ Physiol. 2007;293:H3602–H3607
201. Ignatowska-Jankowska B, Jankowski M, Glac W, et al. Cannabidiol-induced lymphopenia does not involve NKT and NK cells. J Physiol Pharmacol. 2009;60 Suppl 3:99–103
202. Magen I, Avraham Y, Ackerman Z, et al. Cannabidiol ameliorates cognitive and motor impairments in bile-duct ligated mice via 5-HT1A receptor activation. Br J Pharmacol. 2010;159:950–957
203. Barichello T, Ceretta RA, Generoso JS, et al. Cannabidiol reduces host immune response and prevents cognitive impairments in Wistar rats submitted to pneumococcal meningitis. Eur J Pharmacol. 2012;697:158–164
204. Campos AC, Brant F, Miranda AS, et al. Cannabidiol increases survival and promotes rescue of cognitive function in a murine model of cerebral malaria. Neuroscience. 2015;289:166–180
205. Hammell DC, Zhang LP, Ma F, et al. Transdermal cannabidiol reduces inflammation and pain-related behaviours in a rat model of arthritis. Eur J Pain. 2016;20:936–948
206. Lehmann C, Fisher NB, Tugwell B, et al. Experimental cannabidiol treatment reduces early pancreatic inflammation in type 1 diabetes. Clin Hemorheol Microcirc. 2016;64:655–662
207. Khaksar S, Bigdeli MR. Intra-cerebral cannabidiol infusion-induced neuroprotection is partly associated with the TNF-alpha/TNFR1/NF-small ka, CyrillicB pathway in transient focal cerebral ischaemia. Brain Inj. 2017;31:1932–1943
208. Gamble LJ, Boesch JM, Frye CW, et al. Pharmacokinetics, safety, and clinical efficacy of cannabidiol treatment in osteoarthritic dogs. Front Vet Sci. 2018;5:165.
209. Klein M, de Quadros De Bortolli J, Guimaraes FS, et al. Effects of cannabidiol, a Cannabis sativa constituent, on oral wound healing process in rats: clinical and histological evaluation. Phytother Res. 2018;32:2275–2281
210. Rock EM, Limebeer CL, Parker LA. Effect of cannabidiolic acid and (9)-tetrahydrocannabinol on carrageenan-induced hyperalgesia and edema in a rodent model of inflammatory pain. Psychopharmacology (Berl). 2018;235:3259–3271
211. Maresz K, Pryce G, Ponomarev ED, et al. Direct suppression of CNS autoimmune inflammation via the cannabinoid receptor CB1 on neurons and CB2 on autoreactive T cells. Nat Med. 2007;13:492–497
212. Rahimi A, Faizi M, Talebi F, et al. Interaction between the protective effects of cannabidiol and palmitoylethanolamide in experimental model of multiple sclerosis in C57BL/6 mice. Neuroscience. 2015;290:279–287
213. Shapiro CM, Orlina AR, Unger PJ, et al. Marihuana-induced antibody response. J Lab Clin Med. 1976;88:194–201
214. Watson ES, Murphy JC, Turner CE. Allergenic properties of naturally occurring cannabinoids. J Pharm Sci. 1983;72:954–955

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Cannabidiol History and Therapeutic Uses

Identification of CBD Receptors and Other Targets

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CBD effects and mechanisms of immune suppression in lymphocytes

CBD-induced neuroprotection by suppression of microglial cell activation

CBD Effects in Autoimmune Disease Models

EAE and MS

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CBD Immune Enhancement Effects

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