cbd anti inflammatory research

Cbd anti inflammatory research

CBD is readily obtainable in most parts of the United States, though its exact legal status has been in flux. All 50 states have laws legalizing CBD with varying degrees of restriction. In December 2015, the FDA eased the regulatory requirements to allow researchers to conduct CBD trials. In 2018, the Farm Bill made hemp legal in the United States, making it virtually impossible to keep CBD illegal – that would be like making oranges legal, but keeping orange juice illegal.

Is cannabidiol legal?

CBD comes in many forms, including oils, extracts, capsules, patches, vapes, and topical preparations for use on skin. If you’re hoping to reduce inflammation and relieve muscle and joint pain, a topical CBD-infused oil, lotion or cream – or even a bath bomb — may be the best option. Alternatively, a CBC patch or a tincture or spray designed to be placed under the tongue allows CBD to directly enter the bloodstream.

Is CBD safe?

A significant safety concern with CBD is that it is primarily marketed and sold as a supplement, not a medication. Currently, the FDA does not regulate the safety and purity of dietary supplements. So, you cannot be sure that the product you buy has active ingredients at the dose listed on the label. In addition, the product may contain other unknown elements. We also don’t know the most effective therapeutic dose of CBD for any particular medical condition.

Cbd anti inflammatory research

In the small intestine, the involvement of CB1 receptors in the control of intestinal motility during croton oil-induced inflammation was recently demonstrated. Izzo et al. showed that pharmacological administration of cannabinoids is able to delay gastrointestinal transit in croton oil-treated mice [65]. It was further suggested that increased levels of CB1 receptor expression in inflamed jejuna may contribute to this protective effect. CB1 receptors were shown to modulate gastrointestinal motility during croton oil-induced inflammation in mice.

The destruction of the blood–brain barrier in MS is initiated by myelin-specific self-reactive T cells. Infiltration of these cells into the spinal cord and CNS, and their subsequent activation, leads to the elimination of the myelin sheath around the nerves and axons [46,47]. The myelin- specific T cells are usually CD4 + , IL-2R + or MHCII-restricted Th1 cells and they secrete proinflammatory cytokines such as IFN-γ and TNF-α [47]. More recently, Th17 cells have been shown to be involved in the pathogenesis of MS [48,49]. One mechanism of immunosuppression by cannabinoids is the induction of apoptosis and Sanchez et al. demonstrated that WIN55,212-2 blocks a passive form of experimental authoimmune encephalomyelitis (EAE) by inducing apoptosis in encephalitogenic cells through partial activation of the CB2 receptor [50]. A CB1-mediated suppressive pathway has also been shown in myelin-specific T cells [24]. This study demonstrated that ex vivo WIN55,212-2 inhibited T-cell recall response to myelin oligodendrocyte glycoprotein (MOG) peptide, as well as decreasing IL-2, IFN-γ and TNF-α production by MOG-activated T cells. Other synthetic cannabinoids, such as JWH-015 and ACEA, also decreased the number of CD4 + infiltrates in the spinal cord of Theiler’s murine encephalomyelitis virus (TMEV)-infected mice [51]. Mestre et al. showed that decreased infiltration of CD4 + T cells upon WIN55,212-2 treatment in EAE mice is due to decreased intercellular and vascular cell adhesion molecules (ICAM-1 and VCAM-1) expression by endothelial cells. Another novel finding of this study demonstrated that WIN55,212-2 exerted its effects by acting through nuclear receptor PPAR-γ [52].

Microglial cells are the macrophages of the CNS and, during MS, they mediate tissue injury in two main ways: antigen presentation and cytokine/chemokine secretion [51,52]. In the initial stages of inflammation, after activation, microglial cells present antigens to myelin-specific T cells, which results in the activation and proliferation of Th1 lineage cells. Arevalo-Martin et al. demonstrated that cannabinoid agonists WIN55,212-2, ACEA or JWH-015 inhibited the activation of microglial cells by TMEV [51]. The investigators confirmed this finding by studying the morphology of the cells (reactive vs resting) as well as by immunohistochemistry. They showed that, after TMEV activation, MHCII molecules co-localized with Mac-1 in the spinal cord sections; however, after 1-day treatment with various cannabinoid agonists, MHCII expression almost disappeared. During this initial stage, co-stimulatory molecule expression, such as that of CD40, also increased and resulted in TNF-α production via the MAPK and JAK/STAT pathways. Ehrhart and colleagues demonstrated that selective stimulation of the CB2 receptor with JWH-015 on murine microglial cells decreased CD40 expression upon IFN-γ activation. This inhibition in CD40 levels translated into decreased JAK/STAT phosphorylation, and decreased TNF-α and nitric oxide production [53].

Effect of cannabinoids on cytokine and chemokine production.

Cannabinoids & multiple sclerosis

Cannabinoids also exert their immunosuppressive effects on astrocytes. Astrocytes make up 60–70% of brain cells in the CNS and play important roles in neuronal growth, neuronal signaling, glucose metabolism and glutamate removal [54]. During disease progression, astrocytes are activated to secrete cytokines, chemokines and nitric oxide, thereby contributing to the overall inflammatory response. Because astrocytes express both CB1 and CB2 receptors, several studies investigated the inhibitory role of cannabinoids on this cell population in the context of MS. One study investigated the effects of AEA on TMEV-activated primary murine astrocytes. This study showed that AEA stimulated astrocytes and triggered the production of IL-6 in a CB1-mediated pathway [56]. The precise role of IL-6 in the CNS is still unclear; however, it has been reported that IL-6 secretion potentiates neuronal growth factor production. In addition, IL-6 has been shown to inhibit TNF-α production by IFN-γ/IL-1β-stimulated glial cells [57]. In a different study, Molina-Holgado and coworkers showed that AEA and the synthetic CB1 agonist CP-55940 inhibited nitric oxide production by LPS-stimulated astrocytes isolated from 1-day-old mice in a CB1-dependent manner [23]. In 2005, Sheng et al. demonstrated that human fetal astrocytes express both CB1 and CB2 receptors and that treatment of IL-1β-stimulated astrocytes with WIN55,212-2 decreased inflammatory products including nitric oxide, TNF-α, CXCL10, CCL2 and CCL5 ( Figure 1 ) [54].

Other natural and synthetic cannabinoid compounds (CBD, AEA, ajulemic acid [AjA] and JWH-015), whose structures are depicted in Table 1 , have also been shown to induce apoptosis in murine and human T lymphocytes. Cannabidiol, the nonpsychoactive ingredient in cannabis, induced apoptosis in CD4 + and CD8 + T cells at 4–8-μM concentrations by increasing reactive oxygen species (ROS) production as well as caspase 3 and 8 activity [20].

Fatty acid amide hydrolase is the major enzyme involved in the degradation of several bioactive fatty amides, in particular anandamide [11], and its genetic deletion in mice leads to a strongly decreased ability to degrade this endocannabinoid and an increase of anandamide levels in several tissues [66]. FAAH-deficient mice showed significant protection against DNBS treatment. However, because anandamide is believed to act not only through cannabinoid receptors but also through other targets, including the peripheral vanilloid receptor TRPV1 [67], the decreased inflammation in FAAH −/− mice could also be due to the activation of targets other than cannabinoid receptors.

Cannabinoid action on cytokines

Cannabinoids are a group of compounds that mediate their effects through cannabinoid receptors. The discovery of Δ 9 -tetrahydrocannabinol (THC) as the major psychoactive principle in marijuana, as well as the identification of cannabinoid receptors and their endogenous ligands, has led to a significant growth in research aimed at understanding the physiological functions of cannabinoids. Cannabinoid receptors include CB1, which is predominantly expressed in the brain, and CB2, which is primarily found on the cells of the immune system. The fact that both CB1 and CB2 receptors have been found on immune cells suggests that cannabinoids play an important role in the regulation of the immune system. Recent studies demonstrated that administration of THC into mice triggered marked apoptosis in T cells and dendritic cells, resulting in immunosuppression. In addition, several studies showed that cannabinoids downregulate cytokine and chemokine production and, in some models, upregulate T-regulatory cells (Tregs) as a mechanism to suppress inflammatory responses. The endocannabinoid system is also involved in immunoregulation. For example, administration of endocannabinoids or use of inhibitors of enzymes that break down the endocannabinoids, led to immunosuppression and recovery from immune-mediated injury to organs such as the liver. Manipulation of endocannabinoids and/or use of exogenous cannabinoids in vivo can constitute a potent treatment modality against inflammatory disorders. This review will focus on the potential use of cannabinoids as a new class of anti-inflammatory agents against a number of inflammatory and autoimmune diseases that are primarily triggered by activated T cells or other cellular immune components.

Cytokines are the signaling proteins synthesized and secreted by immune cells upon stimulation. They are the modulating factors that balance initiation and resolution of inflammation. One of the possible mechanisms of immune control by cannabinoids during inflammation is the dys-regulation of cytokine production by immune cells and disruption of the well-regulated immune response [25]. Furthermore, cannabinoids may affect immune responses and host resistance by perturbing the balance between the cytokines produced by T-helper subsets, Th1 and Th2. In vitro studies were performed to compare the effect of THC and cannabinol on cytokine production by human T, B, CD8 + , NK and eosinophilic cell lines. However, the results were variable, depending on the cell line and the concentration used [26]. Both pro-inflammatory and anti-inflammatory effects of THC were demonstrated in this study, proposing that different cell populations have varied thresholds of response to cannabinoids. Generally, TNF-α, GM-CSF and IFN-γ levels decreased with drug treatment. Interestingly, while the anti-inflammatory cytokine IL-10 decreased following THC treatment, there was an increase in the proinflammatory cytokine IL-8. In other studies, cannabinoid CP55,940 at nanomolar concentrations was shown to have a stimulatory effect on several cytokines in the human promyelocytic cell line HL-60 [27]. At the molecular level, THC has also been shown to inhibit LPS-stimulated mRNA expression of IL-1α, IL-1β, IL-6 and TNF-α in cultured rat microglial cells; however, the effect was independent of the cannabinoid receptors [28]. In a different study, mice were challenged with Corynebacterium parvum, in vivo, following the administration of the synthetic cannabinoids WIN55,212-2 and HU210. The animals were then challenged with LPS. The results showed decreased levels of TNF-α and IL-12 but increased levels of IL-10 in the serum [29]. This effect was shown to be CB1 receptor dependent.

Cbd anti inflammatory research

The result of an imbalance between oxidants and antioxidants is oxidative stress, the consequences of which are oxidative modifications of lipids, nucleic acids, and proteins. This results in changes in the structure of the above molecules and, as a result, disrupts their molecular interactions and signal transduction pathways [39]. Oxidative modifications play an important role in the functioning of redox-sensitive transcription factors (including Nrf2 and the nuclear factor kappa B (NFκB). As a consequence, oxidative modifications play a role in the regulation of pathological conditions characterized by redox imbalances and inflammation, such as cancer, inflammatory diseases, and neurodegenerative diseases [40,41].

By lowering ROS levels, CBD also protects non-enzymatic antioxidants, preventing their oxidation, as in the case of GSH in the myocardial tissue of C57BL/6J mice with diabetic cardiomyopathy [32] and doxorubicin-treated rats [25]. An increase in GSH levels after CBD treatment was also observed in mouse microglia cells [37] and in the liver of cadmium poisoned mice [25]. This is of great practical importance because GSH cooperates with other low molecular weight compounds in antioxidant action, mainly with vitamins such as A, E, and C [38]. CBD exhibits much more antioxidant activity (30–50%) than α-tocopherol or vitamin C [4].

3.4. Cannabinoid Receptors

CBD has been shown to be a weak agonist of the human, mouse, and rat CB1 receptor [61]. The activation of the CB1 receptor increases ROS production and a pro-inflammatory response, including the downstream synthesis of tumor necrosis factor α (TNF-α) [62]. In addition, it was shown that CBD is a negative allosteric modulator of the CB1 receptor [63]. Regardless of the effect on the CB1 receptor, CBD is a weak agonist of the CB2 receptor [64], but it has also been suggested that it may demonstrate inverse agonism of the CB2 receptor [65]. Importantly, CB2 activation leads to a decrease in ROS and TNF-α levels, which reduces oxidative stress and inflammation [62]. Therefore, it has been suggested that CBD may indirectly improve anti-inflammatory effects. Clinical studies have confirmed that CBD reduces the levels of pro-inflammatory cytokines, inhibits T cell proliferation, induces T cell apoptosis and reduces migration and adhesion of immune cells [66]. In addition, CBD anti-inflammatory activity has been shown to be antagonized by both a selective CB2 antagonist and AEA, an endogenous CB2 receptor agonist [67].

3.3. Indirect Antioxidant Effects of CBD

CBD is an agonist of the PPARγ receptor, which is a member of the nuclear receptor superfamily of ligand-inducible transcription factors [52]. PPARγ, an ubiquitin E3 ligase, has been shown to interact directly with NFκB. The interaction occurs between the ligand-binding domain of PPARγ and the Rel homology domain region of the p65 subunit of NFκB. Lys48-linked polyubiquitin of the ligand-binding domain of PPARγ is responsible for proteosomal degradation of p65 [83]. In this way, PPARγ participates in the modulation of inflammation by inducing ubiquitination proteosomal degradation of p65, which causes inhibition of pro-inflammatory gene expression, such as cyclooxygenase (COX2) and some pro-inflammatory mediators such as TNF-α, IL-1β, and IL-6, as well as inhibition of NFκB-mediated inflammatory signaling [84]. For this reason, PPARγ agonists can play an anti-inflammatory role by inhibiting the NFκB-mediated transcription of downstream genes [84]. This molecular mechanism is mediated by β-catenin and glycogen synthase kinase 3 beta (GSK-3β). β-catenin attenuates transcription of pro-inflammatory genes by inhibiting NFκB [85,86]. On the other hand, GSK-3β is decreased by PPARγ stimulation [87].