Cannabinoid receptors and T helper cells

Role of T and B lymphocyte cannabinoid type 1 and 2 receptors in major depression and suicidal behaviours

Early flow cytometry studies revealed T cell activation in major depressive disorder (MDD). MDD is characterised by activation of the immune-inflammatory response system (IRS) and the compensatory immunoregulatory system (CIRS), including deficits in T regulatory (Treg) cells. This study examines the number of cannabinoid type 1 (CB1) and type 2 (CB2) receptor-bearing T/B lymphocytes in MDD, and the effects of in vitro cannabidiol (CBD) administration on CB1/CB2-bearing immunocytes. Using flow cytometry, we determined the percentage of CD20+CB2+, CD3+CB2+, CD4+CB2+, CD8+CB2+ and FoxP3+CB1+ cells in 19 healthy controls and 29 MDD patients in 5 conditions: baseline, stimulation with anti-CD3/CD28 with or without 0.1 µg/mL, 1.0 µg/mL, or 10.0 µg/mL CBD. CB2+ was significantly higher in CD20+ than CD3+ and CD4+ and CD 8+ cells. Stimulation with anti-CD3/CD8 increases the number of CB2-bearing CD3+, CD4+ and CD8+ cells, as well as CB1-bearing FoxP3+ cells. There was an inverse association between the number of reduced CD4+ CB2+ and IRS profiles, including M1 macrophage, T helper-(Th)-1 and Th-17 phenotypes. MDD is characterised by lowered basal FoxP3+ CB1+% and higher CD20+ CB2+%. 33.2% of the variance in the depression phenome (including severity of depression, anxiety and current suicidal behaviours) is explained by CD20+ CB2+ % (positively) and CD3+ CB2+% (inversely). All five immune cell populations were significantly increased by 10 µg/mL of CBD administration. Reductions in FoxP3+ CB1+% and CD3+ /CD4+ CB2+% contribute to deficits in immune homoeostasis in MDD, while increased CD20+CB2+% may contribute to the pathophysiology of MDD by activating T-independent humoral immunity.

The Perspective of Cannabidiol in Psoriasis Therapy

Psoriasis is a chronic skin condition that can significantly impact the quality of life of those affected. As an autoimmune disease, it can lead to itchy, painful, and scaly patches on the skin. Although various treatments, including topical creams, phototherapy, and systemic medications, are currently available, they may not always offer effective relief and can have side effects. Researchers have thus been exploring the potential benefits of non-psychoactive compounds such as CBD, found in Cannabis sativa plants, for treating psoriasis. CBD treatment may reduce inflammation, oxidative stress, itching, abnormal proliferation of keratinocytes, and may increase hydration. This review aims to provide an overview of the existing literature on the potential uses of CBD for psoriasis treatment.

Cannabinoids' Role in Modulating Central and Peripheral Immunity in Neurodegenerative Diseases

Cannabinoids (the endocannabinoids, the synthetic cannabinoids, and the phytocannabinoids) are well known for their various pharmacological properties, including neuroprotective and anti-inflammatory features, which are fundamentally important for the treatment of neurodegenerative diseases. The aging of the global population is causing an increase in these diseases that require the development of effective drugs to be even more urgent. Taking into account the unavailability of effective drugs for neurodegenerative diseases, it seems appropriate to consider the role of cannabinoids in the treatment of these diseases. To our knowledge, few reviews are devoted to cannabinoids' impact on modulating central and peripheral immunity in neurodegenerative diseases. The objective of this review is to provide the best possible information about the cannabinoid receptors and immuno-modulation features, peripheral immune modulation by cannabinoids, cannabinoid-based therapies for the treatment of neurological disorders, and the future development prospects of making cannabinoids versatile tools in the pursuit of effective drugs.

AEC and AFMSC Transplantation Preserves Fertility of Experimentally Induced Rat Varicocele by Expressing Differential Regenerative Mechanisms

Amniotic membrane and amniotic fluid derived cells are regarded as a promising stem cell source for developing regenerative medicine techniques, although they have never been tested on male infertility diseases such as varicocele (VAR). The current study aimed to examine the effects of two distinct cell sources, human Amniotic Fluid Mesenchymal Stromal Cells (hAFMSCs) and amniotic epithelial cells (hAECs), on male fertility outcomes in a rat induced VAR model. To explain cell-dependent enhancement of reproductive outcomes in rats transplanted with hAECs and hAFMSCs, insights on testis morphology, endocannabinoid system (ECS) expression and inflammatory tissue response have been carried out alongside cell homing assessment. Both cell types survived 120 days post-transplantation by modulating the ECS main components, promoting proregenerative M2 macrophages (Mφ) recruitment and a favorable anti-inflammatory IL10 expression pattern. Of note, hAECs resulted to be more effective in restoring rat fertility rate by enhancing both structural and immunoresponse mechanisms. Moreover, immunofluorescence analysis revealed that hAECs contributed to CYP11A1 expression after transplantation, whereas hAFMSCs moved towards the expression of Sertoli cell marker, SOX9, confirming a different contribution into the mechanisms leading to testis homeostasis. These findings highlight, for the first time, a distinct role of amniotic membrane and amniotic fluid derived cells in male reproduction, thus proposing innovative targeted stem-based regenerative medicine protocols for remedying high-prevalence male infertility conditions such as VAR.

Cannabinoid Receptor 1 Agonist ACEA and Cannabinoid Receptor 2 Agonist GW833972A Attenuates Cell-Mediated Immunity by Different Biological Mechanisms

Cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) are components in the endocannabinoid system that play significant roles in regulating immune responses. There are many agonists for the cannabinoid receptors; however, their effects on T cell regulation have not been elucidated. In the present study, we determined the effects of the CB1 selective agonist ACEA and the CB2 selective agonist GW833972A on T cell responses. It was found that both agonists impaired anti-CD3 monoclonal antibody induced T cell proliferation. However, ACEA and GW833972A agonists down-regulated the expression of activation markers on CD4+ and CD8+ T cells and co-stimulatory molecules on B cells and monocytes in different manners. Moreover, only GW833972A suppressed the cytotoxic activities of CD8+ T cells without interfering in the cytotoxic activities of CD4+ T cells and NK cells. In addition, the CB2 agonist, but not CB1 agonist, caused the reduction of Th1 cytokine production. Our results demonstrated that the CB1 agonist ACEA and CB2 agonist GW833972A attenuated cell-mediated immunity in different mechanisms. These agonists may be able to be used as therapeutic agents for inducing T cell hypofunction in inflammatory and autoimmune diseases.

Trends in inflammatory bowel disease treatment in the past two decades-a high-level text mining analysis of PubMed publications

AIM

Many therapeutic options for inflammatory bowel disease (IBD) emerged during the last 2 decades, along with the rise in disease prevalence and incidence. We aimed at assessing the published literature on different treatment options in that period. Special attention was attributed to specific medication mechanisms and geographic diversity.

MATERIALS AND METHODS

We have queried PubMed for all available IBD-related entries published during 2000-2020. The following data were extracted for each entry: PubMed unique article ID (PMID), title, publishing journal, abstract text, keywords (if any), and authors' affiliations. Two gastrointestinal specialists decided in consensus on a list of terms to classify entries. The terms belonged to five treatment groups: medical, surgical, dietary, microbiome manipulation, and complementary medicine. The medical and complementary medicine groups were further sub-classified. Annual trends of publications for the years 2000-2020 were plotted for different treatment types. The slopes of publication trends were calculated by fitting regression lines to the annual number of publications.

RESULTS

Overall, 77,505 IBD entries were published between 2000 and 2020. Medical treatment showed the highest number of total publications 21,540/77,505 (27.8%), followed by surgical 7605/77,505 (9.8%), microbiome research 5260/77,505 (6.8%), dietary 4819/77,505 (6.2%), and complementary medicine treatment 762/77,505 (1.0%). Interestingly, since 2012 there is a steep rise in microbiome publications that outnumbered surgery in the last 2 years. Trend analysis of medical treatment showed that biologics had the steepest slope (57.5, p < 0.001), followed by immunomodulators (4.9, p < 0.001), small molecules (3.9, p < 0.001), and 5-ASA (3.8, p < 0.001).

CONCLUSION

According to our high-level publications trend analysis, the past 2 decades certainly deserve the reference as the "biologic era", as publications regarding biological therapy outnumbered all other treatment options. Interestingly, though very popular among patients, complementary medicine was not studied with correlation to its' acceptance among patients.

Analytical approaches to assess metabolic changes in psoriasis

Psoriasis is one of the most common human skin diseases, although its development is not limited to one tissue, but is associated with autoimmune reactions throughout the body. Overproduction of pro-inflammatory cytokines and growth factors systemically stimulates the proliferation of skin cells, which manifests as excessive exfoliation of the epidermis, and/or arthritis, as well as other comorbidities such as insulin resistance, metabolic syndrome, hypertension, and depression. Thus, there is a great need for a thorough analysis of the pathophysiology of psoriatic patients, including classical methods, such as spectrophotometry, chromatography, or Western blot, and also novel omics approaches such as lipidomics and proteomics. Moreover, the extensive pathophysiology forces increased research examining biological changes in both skin cells, and systemically. A wide range of techniques involved in lipidomic research based on a combination of mass spectrometry and different types of chromatography (RP-LC-QTOF-MS/MS, HILIC-QTOF-MS/MS or RP-LC-QTRAP-MS/MS), have allowed comprehensive assessment of lipid modification in psoriatic skin and provided new insight into the role of lipids and their mechanism of action in psoriasis. Moreover, proteomic analysis using gel-nanoLC-OrbiTrap-MS/MS, as well as MALDI-TOF/TOF techniques facilitates the description of panels of enzymes involved in lipidome modifications, and the response of the endocannabinoid system to metabolic changes. Psoriasis is known to alter the expression of proteins that are involved in the inflammatory and antioxidant response, as well as protein biosynthesis, degradation, as well as cell proliferation and apoptosis. Knowledge of changes in the lipidomic and proteomic profile will not only allow the understanding of psoriasis pathophysiology, but also facilitate proper and early diagnosis and effective pharmacotherapy.

Evaluation of the preclinical analgesic efficacy of naturally derived, orally administered oil forms of Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and their 1:1 combination

Chronic neuropathic pain (NP) is a growing clinical problem for which effective treatments, aside from non-steroidal anti-inflammatory drugs and opioids, are lacking. Cannabinoids are emerging as potentially promising agents to manage neuroimmune effects associated with nociception. In particular, Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and their combination are being considered as therapeutic alternatives for treatment of NP. This study aimed to examine whether sex affects long-term outcomes on persistent mechanical hypersensitivity 7 weeks after ceasing cannabinoid administration. Clinically relevant low doses of THC, CBD, and a 1:1 combination of THC:CBD extracts, in medium chain triglyceride (MCT) oil, were orally gavaged for 14 consecutive days to age-matched groups of male and female sexually mature Sprague Dawley rats. Treatments commenced one day after surgically inducing a pro-nociceptive state using a peripheral sciatic nerve cuff. The analgesic efficacy of each phytocannabinoid was assessed relative to MCT oil using hind paw mechanical behavioural testing once a week for 9 weeks. In vivo intracellular electrophysiology was recorded at endpoint to characterize soma threshold changes in primary afferent sensory neurons within dorsal root ganglia (DRG) innervated by the affected sciatic nerve. The thymus, spleen, and DRG were collected post-sacrifice and analyzed for long-term effects on markers associated with T lymphocytes at the RNA level using qPCR. Administration of cannabinoids, particularly the 1:1 combination of THC, elicited a sustained mechanical anti-hypersensitive effect in males with persistent peripheral NP, which corresponded to beneficial changes in myelinated Aβ mechanoreceptive fibers. Specific immune cell markers associated with T cell differentiation and pro-inflammatory cytokines, previously implicated in repair processes, were differentially up-regulated by cannabinoids in males treated with cannabinoids, but not in females, warranting further investigation into sexual dimorphisms that may underlie treatment outcomes.

Altered Lipid Metabolism in Blood Mononuclear Cells of Psoriatic Patients Indicates Differential Changes in Psoriasis Vulgaris and Psoriatic Arthritis

The aim of this study was to investigate possible stress-associated disturbances in lipid metabolism in mononuclear cells, mainly lymphocytes of patients with psoriasis vulgaris (Ps, n = 32) or with psoriatic arthritis (PsA, n = 16) in respect to the healthy volunteers (n = 16). The results showed disturbances in lipid metabolism of psoriatic patients reflected by different phospholipid profiles. The levels of non-enzymatic lipid metabolites associated with oxidative stress 8-isoprostaglandin F2α (8-isoPGF2α) and free 4-hydroxynonenal (4-HNE) were higher in PsA, although levels of 4-HNE-His adducts were higher in Ps. In the case of the enzymatic metabolism of lipids, enhanced levels of endocannabinoids were observed in both forms of psoriasis, while higher expression of their receptors and activities of phospholipases were detected only in Ps. Moreover, cyclooxygenase-1 (COX-1) activity was enhanced only in Ps, but cyclooxygenase-2 (COX-2) was enhanced both in Ps and PsA, generating higher levels of eicosanoids: prostaglandin E1 (PGE1), leukotriene B4 (LTB4), 13-hydroxyoctadecadienoic acid (13HODE), thromboxane B2 (TXB2). Surprisingly, some of major eicosanoids 15-d-PGJ₂ (15-deoxy-Δ12,14-prostaglandin J₂), 15-hydroxyeicosatetraenoic acid (15-HETE) were elevated in Ps and reduced in PsA. The results of our study revealed changes in lipid metabolism with enhancement of immune system-modulating mediators in psoriatic mononuclear cells. Evaluating further differential stress responses in Ps and PsA affecting lipid metabolism and immunity might be useful to improve the prevention and therapeutic treatments of psoriasis.

Oxidative burst and Dectin-1-triggered phagocytosis affected by norepinephrine and endocannabinoids: implications for fungal clearance under stress

A prolonged stress burden is known to hamper the efficiency of both the innate and the adaptive immune systems and to attenuate the stress responses by the catecholaminergic and endocannabinoid (EC) systems. Key mechanisms of innate immunity are the eradication of pathogens through phagocytosis and the respiratory burst. We tested the concentration-dependent, spontaneous and stimulated (via TNFα and N-formylmethionine-leucyl-phenylalanine) release of reactive oxygen species (ROS) by human polymorphonuclear leukocytes (PMNs) in vitro in response to norepinephrine (NE) and AM1241, a pharmacological ligand for the EC receptor CB2. We evaluated phagocytosis of Dectin-1 ligating zymosan particles and tested the cytokine response against Candida antigen in an in vitro cytokine release assay. Increasing concentrations of NE did not affect phagocytosis, yet stimulated ROS release was attenuated gradually reaching maximum suppression at 500 nM. Adrenergic receptor (AR) mechanisms using non-AR-selective (labetalol) as well as specific α-(prazosin) and β-(propranolol) receptor antagonists were tested. Results show that only labetalol and propranolol were able to recuperate cytotoxicity in the presence of NE, evidencing a β-receptor-mediated effect. The CB2 agonist, AM1241, inhibited phagocytosis at 10 µM and spontaneous peroxide release by PMNs. Use of the inverse CB2 receptor agonist SR144528 led to partial recuperation of ROS production, confirming the functional role of CB2. Additionally, AM1241 delayed early activation of monocytes and induced suppression of IL-2 and IL-6 levels in response to Candida via lower activity of mammalian target of rapamycin (mTOR). These findings provide new insights into key mechanisms of innate immunity under stressful conditions where ligands to the sympatho-adrenergic and EC system are released.

The endocannabinoid system of the skin. A potential approach for the treatment of skin disorders

The skin is the largest organ of the body and has a complex and very active structure that contributes to homeostasis and provides the first line defense against injury and infection. In the past few years it has become evident that the endocannabinoid system (ECS) plays a relevant role in healthy and diseased skin. Specifically, we review how the dysregulation of ECS has been associated to dermatological disorders such as atopic dermatitis, psoriasis, scleroderma and skin cancer. Therefore, the druggability of the ECS could open new research avenues for the treatment of the pathologies mentioned. Numerous studies have reported that phytocannabinoids and their biological analogues modulate a complex network pharmacology involved in the modulation of ECS, focusing on classical cannabinoid receptors, transient receptor potential channels (TRPs), and peroxisome proliferator-activated receptors (PPARs). The combined targeting of several end-points seems critical to provide better chances of therapeutically success, in sharp contrast to the one-disease-one-target dogma that permeates current drug discovery campaigns.

Therapeutic Cannabis and Endocannabinoid Signaling System Modulator Use in Otolaryngology Patients

Objectives

1) review benefits and risks of cannabis use, with emphasis on otolaryngic disease processes; 2) define and review the endocannabinoid signaling system (ESS); and 3) review state and federal regulations for the use and research of cannabis and ESS modulators.

Methods

This manuscript is a review of the current literature relevant to the stated objectives.

Results

Cannabis (marijuana) use is increasing. It is the most widely used illicit substance in the world. There is increasing interest in its therapeutic potential due to changing perceptions, new research, and legislation changes controlling its use. The legal classification of cannabis is complicated due to varied and conflicting state and federal laws. There are currently two synthetic cannabinoid drugs that are FDA approved. Current indications for use include chemotherapy‐related nausea and vomiting, cachexia, and appetite loss. Research has demonstrated potential benefit for use in many other pathologies including pain, inflammatory states, and malignancy. Data exists demonstrating potential antineoplastic benefit in oral, thyroid, and skin cancers.

Conclusions

ESS modulators may play both a causal and therapeutic role in several disorders seen in otolaryngology patients. The use of cannabis and cannabinoids is not without risk. There is a need for further research to better understand both the adverse and therapeutic effects of cannabis use. With increasing rates of consumption, elevated public awareness, and rapidly changing legislation, it is helpful for the otolaryngologist to be aware of both the adverse manifestations of use and the potential therapeutic benefits when talking with patients.

Immune System Dysregulation During Spaceflight: Potential Countermeasures for Deep Space Exploration Missions

Recent studies have established that dysregulation of the human immune system and the reactivation of latent herpesviruses persists for the duration of a 6-month orbital spaceflight. It appears certain aspects of adaptive immunity are dysregulated during flight, yet some aspects of innate immunity are heightened. Interaction between adaptive and innate immunity also seems to be altered. Some crews experience persistent hypersensitivity reactions during flight. This phenomenon may, in synergy with extended duration and galactic radiation exposure, increase specific crew clinical risks during deep space exploration missions. The clinical challenge is based upon both the frequency of these phenomena in multiple crewmembers during low earth orbit missions and the inability to predict which specific individual crewmembers will experience these changes. Thus, a general countermeasure approach that offers the broadest possible coverage is needed. The vehicles, architecture, and mission profiles to enable such voyages are now under development. These include deployment and use of a cis-Lunar station (mid 2020s) with possible Moon surface operations, to be followed by multiple Mars flyby missions, and eventual human Mars surface exploration. Current ISS studies will continue to characterize physiological dysregulation associated with prolonged orbital spaceflight. However, sufficient information exists to begin consideration of both the need for, and nature of, specific immune countermeasures to ensure astronaut health. This article will review relevant in-place operational countermeasures onboard ISS and discuss a myriad of potential immune countermeasures for exploration missions. Discussion points include nutritional supplementation and functional foods, exercise and immunity, pharmacological options, the relationship between bone and immune countermeasures, and vaccination to mitigate herpes (and possibly other) virus risks. As the immune system has sentinel connectivity within every other physiological system, translational effects must be considered for all potential immune countermeasures. Finally, we shall discuss immune countermeasures in the context of their individualized implementation or precision medicine, based on crewmember specific immunological biases.

Complementary Therapies in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs) often take a chronic debilitating course. Given the chronicity of IBD, the limitations of the available medications, their potential side effects, and the impact of the disease on patients' quality of life, it is not surprising IBD patients are ranked among the highest users of complementary and alternative medicine (CAM). Since CAM has become very popular in real-life practice of Western Communities, caregivers must gain more knowledge about these therapies, their mechanism of action, benefits, and risks. This article reviews and discusses up-to-date scientific and clinical data regarding the most prevalent herbal CAM therapies.

Attenuation of antigen-specific T helper 1 immunity by Neolitsea hiiranensis and its derived terpenoids

Background

T cells play a pivotal role in the adaptive immunity that participates in a wide range of immune responses through a complicated cytokine network. Imbalance of T-cell responses is involved in several immune disorders. Neolitsea species, one of the biggest genera in the family Lauraceae, have been employed widely as folk medicines for a long time in Asia. Previous phytochemical investigations revealed the abundance of terpenes in the leaves of N. hiiranensis, an endemic Neolitsea in Taiwan, and demonstrated anti-inflammatory activities. However, the effect of N. hiiranensis on the functionality of immune cells, especially T cells, is still unclear. In this study, we utilize in vitro and in vivo approaches to characterize the effects of leaves of N. hiiranensis and its terpenoids on adaptive immune responses.

Methods

Dried leaves of N. hiiranensis were extracted three times with cold methanol to prepare crude extracts and to isolate its secondary metabolites. The ovalbumin (OVA)-sensitized BALB/c mice were administrated with N. hiiranensis extracts (5–20 mg/kg). The serum and splenocytes of treated mice were collected to evaluate the immunomodulatory effects of N. hiiranensis on the production of OVA-specific antibodies and cytokines. To further identify the N. hiiranensis-derived compounds with immunomodulatory potentials, OVA-primed splenocytes were treated with compounds isolated from N. hiiranensis by determining the cell viability, cytokine productions, and mRNA expression in the presence of OVA in vitro.

Results

Crude extracts of leaves of N. hiiranensis significantly inhibited IL-12, IFN-γ, and IL-2 cytokine productions as well as the serum levels of antigen-specific IgM and IgG_2ain vivo. Two of fourteen selected terpenoids and one diterpenoid derived from the leaves of N. hiiranensis suppressed IFN-γ in vitro. In addition, β-caryophyllene oxide attenuated the expression of IFN-γ, T-bet, and IL-12Rβ2 in a dose-dependent manner. N. hiiranensis-derived β-caryophyllene oxide inhibited several aspects of adaptive immune responses, including T-cell differentiation, IFN-γ production, and Th1-assocaited genes.

Conclusion

As IFN-γ is the key cytokine secreted by T helper-1 cells and plays a pivotal role in Th1 immune responses, our results suggested that the N. hiiranensis and its terpenoids may possess potential therapeutic effects on Th1-mediated immune disorders.

Turning Over a New Leaf: Cannabinoid and Endocannabinoid Modulation of Immune Function

Cannabis is a complex substance that harbors terpenoid-like compounds referred to as phytocannabinoids. The major psychoactive phytocannabinoid found in cannabis ∆(9)-tetrahydrocannabinol (THC) produces the majority of its pharmacological effects through two cannabinoid receptors, termed CB1 and CB2. The discovery of these receptors as linked functionally to distinct biological effects of THC, and the subsequent development of synthetic cannabinoids, precipitated discovery of the endogenous cannabinoid (or endocannabinoid) system. This system consists of the endogenous lipid ligands N- arachidonoylethanolamine (anandamide; AEA) and 2-arachidonylglycerol (2-AG), their biosynthetic and degradative enzymes, and the CB1 and CB2 receptors that they activate. Endocannabinoids have been identified in immune cells such as monocytes, macrophages, basophils, lymphocytes, and dendritic cells and are believed to be enzymatically produced and released "on demand" in a similar fashion as the eicosanoids. It is now recognized that other phytocannabinoids such as cannabidiol (CBD) and cannabinol (CBN) can alter the functional activities of the immune system. This special edition of the Journal of Neuroimmune Pharmacology (JNIP) presents a collection of cutting edge original research and review articles on the medical implications of phytocannabinoids and the endocannabinoid system. The goal of this special edition is to provide an unbiased assessment of the state of research related to this topic from leading researchers in the field. The potential untoward effects as well as beneficial uses of marijuana, its phytocannabinoid composition, and synthesized cannabinoid analogs are discussed. In addition, the role of the endocannabinoid system and approaches to its manipulation to treat select human disease processes are addressed.

Differential role of cannabinoids in the pathogenesis of skin cancer

AIM

Cannabinoids (CB) like ∆(9)-tetrahydrocannabinol (THC) can induce cancer cell apoptosis and inhibit angiogenesis. However, the use of cannabinoids for the treatment of malignant diseases is discussed controversially because of their immunomodulatory effects which can suppress anti-tumor immunity. Here we investigated the role of exogenous and endogenous cannabinoids in mouse skin cancer.

MAIN METHODS

First we examined the effect of THC, which binds to CB receptors (CB1, CB2), on the growth of the mouse melanoma cell lines B16 and HCmel12 in vitro and in vivo in wild type (WT) and CB1/CB2-receptor deficient mice (Cnr1/2(-/-)). Next we evaluated the role of the endogenous cannabinoid system by studying the growth of chemically induced melanomas, fibrosarcoma and papillomas in WT and Cnr1/2(-/-) mice.

KEY FINDINGS

THC significantly inhibited tumor growth of transplanted HCmel12 melanomas in a CB receptor-dependent manner in vivo through antagonistic effects on its characteristic pro-inflammatory microenvironment. Chemically induced skin tumors developed in a similar manner in Cnr1/2(-/-) mice when compared to WT mice.

SIGNIFICANCE

Our results confirm the value of exogenous cannabinoids for the treatment of melanoma but do not support a role for the endogenous cannabinoid system in the pathogenesis of skin cancer.

Elevated levels of endocannabinoids in chronic hepatitis C may modulate cellular immune response and hepatic stellate cell activation

The endocannabinoid (EC) system is implicated in many chronic liver diseases, including hepatitis C viral (HCV) infection. Cannabis consumption is associated with fibrosis progression in patients with chronic hepatitis C (CHC), however, the role of ECs in the development of CHC has never been explored. To study this question, anandamide (AEA) and 2-arachidonoyl glycerol (2-AG) were quantified in samples of HCV patients and healthy controls by gas and liquid chromatography mass spectrometry. Fatty acid amide hydrolase (FAAH) and monoaclyglycerol lipase (MAGL) activity was assessed by [³H]AEA and [³H]2-AG hydrolysis, respectively. Gene expression and cytokine release were assayed by TaqMan PCR and ELISpot, respectively. AEA and 2-AG levels were increased in plasma of HCV patients, but not in liver tissues. Hepatic FAAH and MAGL activity was not changed. In peripheral blood mononuclear cells (PBMC), ECs inhibited IFN-γ, TNF-α, and IL-2 secretion. Inhibition of IL-2 by endogenous AEA was stronger in PBMC from HCV patients. In hepatocytes, 2-AG induced the expression of IL-6, -17A, -32 and COX-2, and enhanced activation of hepatic stellate cells (HSC) co-cultivated with PBMC from subjects with CHC. In conclusion, ECs are increased in plasma of patients with CHC and might reveal immunosuppressive and profibrogenic effects.

Modulation of gut-specific mechanisms by chronic δ(9)-tetrahydrocannabinol administration in male rhesus macaques infected with simian immunodeficiency virus: a systems biology analysis

Our studies have demonstrated that chronic Δ(9)-tetrahydrocannabinol (THC) administration results in a generalized attenuation of viral load and tissue inflammation in simian immunodeficiency virus (SIV)-infected male rhesus macaques. Gut-associated lymphoid tissue is an important site for HIV replication and inflammation that can impact disease progression. We used a systems approach to examine the duodenal immune environment in 4- to 6-year-old male rhesus monkeys inoculated intravenously with SIVMAC251 after 17 months of chronic THC administration (0.18-0.32 mg/kg, intramuscularly, twice daily). Duodenal tissue samples excised from chronic THC- (N=4) and vehicle (VEH)-treated (N=4) subjects at ∼5 months postinoculation showed lower viral load, increased duodenal integrin beta 7(+)(β7) CD4(+) and CD8(+) central memory T cells, and a significant preferential increase in Th2 cytokine expression. Gene array analysis identified six genes that were differentially expressed in intestinal samples of the THC/SIV animals when compared to those differentially expressed between VEH/SIV and uninfected controls. These genes were identified as having significant participation in (1) apoptosis, (2) cell survival, proliferation, and morphogenesis, and (3) energy and substrate metabolic processes. Additional analysis comparing the duodenal gene expression in THC/SIV vs. VEH/SIV animals identified 93 differentially expressed genes that participate in processes involved in muscle contraction, protein folding, cytoskeleton remodeling, cell adhesion, and cell signaling. Immunohistochemical staining showed attenuated apoptosis in epithelial crypt cells of THC/SIV subjects. Our results indicate that chronic THC administration modulated duodenal T cell populations, favored a pro-Th2 cytokine balance, and decreased intestinal apoptosis. These findings reveal novel mechanisms that may potentially contribute to cannabinoid-mediated disease modulation.

Endocannabinoids as biomarkers of human reproduction

BACKGROUND

Infertility is a condition of the reproductive system that affects ∼10-15% of couples attempting to conceive a baby. More than half of all cases of infertility are a result of female conditions, while the remaining cases can be attributed to male factors, or to a combination of both. The search for suitable biomarkers of pregnancy outcome is a challenging issue in human reproduction, aimed at identifying molecules with predictive significance of the reproductive potential of male and female gametes. Among the various candidates, endocannabinoids (eCBs), and in particular anandamide (AEA), represent potential biomarkers of human fertility disturbances. Any perturbation of the balance between synthesis and degradation of eCBs will result in local changes of their tone in human female and male reproductive tracts, which in turn regulates various pathophysiological processes, oocyte and sperm maturation included.

METHODS

PubMed and Web of Science databases were searched for papers using relevant keywords like 'biomarker', 'endocannabinoid', 'infertility', 'pregnancy' and 'reproduction'.

RESULTS

In this review, we discuss different studies on the measurements of AEA and related eCBs in human reproductive cells, tissues and fluids, where the local contribution of these bioactive lipids could be critical in ensuring normal sperm fertilizing ability and pregnancy.

CONCLUSION

Based on the available data, we suggest that the AEA tone has the potential to be exploited as a novel diagnostic biomarker of infertility, to be used in association with assays of conventional hormones (e.g. progesterone, β-chorionic gonadotrophin) and semen analysis. However further quantitative research of its predictive capacity is required.

Marijuana use and brain immune mechanisms

The recreational smoking of marijuana, or Cannabis sativa, has become widespread, including among adolescents. Marijuana contains a class of compounds known as phytocannabinoids that include cannabidiol (CBD) and Δ(9)-tetrahydrocannabinol (THC). THC is the major psychoactive component in marijuana, but also exhibits immunosuppressive activity. CBD, while not psychotropic, also modulates immune function, but its mechanism of action appears to differ from that of THC. Since both compounds are highly lipophilic, they readily passage the blood-brain barrier and access the central nervous system. Since CBD is not psychotropic, it has been considered as a candidate therapeutic compound for ablating neuropathological processes characterized by hyperinflammation. However, an unresolved question centers around the impact of these compounds on immune-competent cells within the CNS in relation to susceptibility to infection. There are accumulating data indicating that THC inhibits the migratory capability of macrophage-like cells resident in the CNS, such as microglia, toward nodes of microbial invasion. Furthermore, phytocannabinoids have been reported to exert developmental and long-term effects on the immune system suggesting that exposure to these substances during an early stage in life has the potential to alter the fundamental neuroimmune response to select microbial agents in the adult.

Characterization of endocannabinoid-mediated induction of myeloid-derived suppressor cells involving mast cells and MCP-1

Endocannabinoids are lipid-signaling molecules found in the nervous system; however, their precise role in the periphery is unclear. In the current study, we observed that a single i.p. administration of AEA caused rapid induction of MDSCs. The MDSCs contained a mixture of granulocytic and monocytic subtypes and expressed Arg-1 and iNOS. The MDSCs suppressed T cell proliferation in vitro and used iNOS to mediate their effect. Moreover, adoptive transfer of MDSCs led to suppression of mBSA-induced DTH. Through the use of pharmacological inhibition, as well as genetic knockout mice, we found that the induction of MDSCs by AEA was CB1-dependent. The induction of MDSCs by AEA was reduced significantly in mast cell-deficient mice, while maintained in LPS-insensitive mice, showing that the induction of MDSCs by AEA was dependent, at least in part, on mast cells and independent of TLR4. Chemokine analysis of AEA- treated WT mice showed an early spike of MCP-1, which was decreased in Kit(W/W-sh) mice, showing a role of mast cells in the secretion of MCP-1 in response to AEA. Also, use of antibodies against MCP-1 or mice deficient in MCP-1 confirmed the role played by MCP-1. Interestingly, MCP-1 played a significant role in the induction of monocytic but not granulocytic MDSCs. Our studies demonstrate for the first time that endocannaboinids activate CB1 on mast cells to induce MCP-1, which facilitates recruitment of monocytic MDSCs.

Microarray and pathway analysis reveal distinct mechanisms underlying cannabinoid-mediated modulation of LPS-induced activation of BV-2 microglial cells

Cannabinoids are known to exert immunosuppressive activities. However, the mechanisms which contribute to these effects are unknown. Using lipopolysaccharide (LPS) to activate BV-2 microglial cells, we examined how Δ⁹-tetrahydrocannabinol (THC), the major psychoactive component of marijuana, and cannabidiol (CBD) the non-psychoactive component, modulate the inflammatory response. Microarray analysis of genome-wide mRNA levels was performed using Illumina platform and the resulting expression patterns analyzed using the Ingenuity Pathway Analysis to identify functional subsets of genes, and the Ingenuity System Database to denote the gene networks regulated by CBD and THC. From the 5338 transcripts that were differentially expressed across treatments, 400 transcripts were found to be upregulated by LPS, 502 by CBD+LPS and 424 by THC+LPS, while 145 were downregulated by LPS, 297 by CBD+LPS and 149 by THC+LPS, by 2-fold or more (p≤0.005). Results clearly link the effects of CBD and THC to inflammatory signaling pathways and identify new cannabinoid targets in the MAPK pathway (Dusp1, Dusp8, Dusp2), cell cycle related (Cdkn2b, Gadd45a) as well as JAK/STAT regulatory molecules (Socs3, Cish, Stat1). The impact of CBD on LPS-stimulated gene expression was greater than that of THC. We attribute this difference to the fact that CBD highly upregulated several genes encoding negative regulators of both NFκB and AP-1 transcriptional activities, such as Trib3 and Dusp1 known to be modulated through Nrf2 activation. The CBD-specific expression profile reflected changes associated with oxidative stress and glutathione depletion via Trib3 and expression of ATF4 target genes. Furthermore, the CBD affected genes were shown to be controlled by nuclear factors usually involved in regulation of stress response and inflammation, mainly via Nrf2/Hmox1 axis and the Nrf2/ATF4-Trib3 pathway. These observations indicate that CBD, and less so THC, induce a cellular stress response and that this response underlies their high immunosuppressant activities.

Expression and functions of μ-opioid receptors and cannabinoid receptors type 1 in T lymphocytes

Opioids and cannabinoids modulate T lymphocyte functions. Many effects of the drugs are mediated by μ-opioid receptor and cannabinoid receptor type 1 (CB1), respectively. These two receptors are strikingly similar with respect to their expression in T cells and the mechanisms by which they mediate modulation of T cell activity. Thus, μ-opioid receptors and CB1 not expressed in resting primary human and Jurkat T cells. However, in response to the cytokine IL-4, the epigenetic modifiers 5-aza-2'-deoxycytidine and trichostatin A, and activation of T cells, functional μ-opioid receptors and CB1 are induced. The induced receptors mediate inhibition of T cell signaling and, thereby, IL-2 production, a hallmark of activated T cells. Although coupled to inhibitory G proteins, μ-opioid receptors and CB1 produce a remarkable increase in cAMP levels in T cells stimulated with opioids and cannabinoids, which is a key mechanism for the inhibition of T cell signaling.

The role of endocannabinoids in gonadal function and fertility along the evolutionary axis

Endocannabinoids are natural lipids able to bind to cannabinoid and vanilloid receptors. Their biological actions at the central and peripheral level are under the tight control of the proteins responsible for their synthesis, transport and degradation. In the last few years, several reports have pointed out these lipid mediators as critical signals, together with sex hormones and cytokines, in various aspects of animal and human reproduction. The identification of anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in reproductive cells and tissues of invertebrates, vertebrates and mammals highlights the key role played by these endogenous compounds along the evolutionary axis. Here, we review the main actions of endocannabinoids on female and male reproductive events, and discuss the interplay between them, steroid hormones and cytokines in regulating fertility. In addition, we discuss the involvement of endocannabinoid signalling in ensuring a correct chromatin remodeling, and hence a good DNA quality, in sperm cells.

Regulation of opioid and cannabinoid receptor genes in human neuroblastoma and T cells by the epigenetic modifiers trichostatin A and 5-aza-2'-deoxycytidine

OBJECTIVE

The aim of this study was to investigate the effect of the epigenetic modifiers trichostatin A and 5-aza-2'-deoxycytidine on the expression of the cannabinoid receptors CB1 and CB2 and μ-opioid receptors in human SH SY5Y neuroblastoma cells and human Jurkat T lymphocytes.

METHODS

Using quantitative real-time RT-PCR, mRNA specific for the aforementioned receptors was determined. The functionality of the induced receptors was determined by analyzing the effect of the ligands to regulate intracellular cAMP.

RESULTS

We demonstrated that treatment of SH SY5Y cells, which endogenously express μ-opioid receptors and CB1, but not CB2, resulted in de novo induction of CB2, while mRNA levels of CB1 and μ-opioid receptors were not significantly altered. In contrast, treatment of Jurkat lymphocytes, which endogenously express CB2, but not CB1 and μ-opioid receptors, resulted in de novo induction of CB1 and μ-opioid receptors, while mRNA levels of CB2 were not significantly altered. Furthermore, the functionality of the induced μ-opioid receptors and CB1 in the Jurkat cells was demonstrated.

CONCLUSIONS

Our data suggest an epigenetically regulated expression of cannabinoid receptors and μ-opioid receptors. Their induction by epigenetic modifiers in distinct cells of the nervous and immune system might result in increased effects of the cognate drugs on neuronal and immune functions. Such modifications might be useful for novel therapies for various disorders, e.g. multiple sclerosis, where the elevated transmission of cannabinoid or opioid signals is beneficial.

Inverse agonism of cannabinoid CB1 receptor blocks the adhesion of encephalitogenic T cells in inflamed brain venules by a protein kinase A-dependent mechanism

It is well known that the cannabinoid system has a significant role in the regulation of the immune responses. Cannabinoid receptors CB1 and CB2 are expressed on T lymphocytes and mediate the immunomodulatory effects of cannabinoids on T cell functions. Here we show that the treatment of proteolipid protein (PLP)139-151-specific T cells with SR141716A, a CB1 inverse agonist and prototype of the diarylpyrazoles series, induced a strong inhibition of firm adhesion in inflamed brain venules in intravital microscopy experiments. In contrast, SR144528, a potent CB2 inverse agonist, had no significant effect on both rolling and arrest of activated T cells. In addition, two analogs of SR141716A and CB1 inverse agonists, AM251 and AM281 inhibited encephalitogenic T cell adhesion suggesting that selective CB1 inverse agonism interfere with lymphocyte trafficking in the CNS. Flow cytometry experiments showed that CB1 inverse agonists have no effect on adhesion molecule expression suggesting that CB1 blockade interferes with signal transduction pathways controlling T cell adhesion in inflamed brain venules. In addition, integrin clustering was not altered after treatment with CB1 inverse agonists suggesting that adhesion blockade is not due to the modulation of integrin valency. Notably, the inhibitory effect exerted by AM251 and AM281 on the adhesive interactions was completely reverted in the presence of protein kinase A (PKA) inhibitor H89, suggesting that cAMP and PKA activation play a key role in the adhesion blockade mediated by CB1 inverse agonists. To further strengthen these results and unveil a previously unknown inhibitory role of cAMP on activated T cell adhesion in vivo in the context of CNS inflammation, we showed that intracellular increase of cAMP induced by treatment with Bt2cAMP, a permeable analog of cAMP, and phosphodiesterase (PDE) inhibitor theophylline efficiently blocked the arrest of encephalitogenic T cells in inflamed brain venules. Our data show that modulation of CB1 function has anti-inflammatory effects and suggests that inverse agonism of CB1 block signal transduction mechanisms controlling encephalitogenic T cells adhesion in inflamed brain venules by a PKA-dependent mechanism.

Cannabinoid receptor 2 and its agonists mediate hematopoiesis and hematopoietic stem and progenitor cell mobilization

Endocannabinoids are arachidonic acid derivatives and part of a novel bioactive lipid signaling system, along with their G-coupled cannabinoid receptors (CB₁ and CB₂) and the enzymes involved in their biosynthesis and degradation. However, their roles in hematopoiesis and hematopoietic stem and progenitor cell (HSPC) functions are not well characterized. Here, we show that bone marrow stromal cells express endocannabinoids (anandamide and 2-arachidonylglycerol), whereas CB₂ receptors are expressed in human and murine HSPCs. On ligand stimulation with CB₂ agonists, CB₂ receptors induced chemotaxis, migration, and enhanced colony formation of bone marrow cells, which were mediated via ERK, PI3-kinase, and Gαi-Rac1 pathways. In vivo, the CB₂ agonist AM1241 induced mobilization of murine HSPCs with short- and long-term repopulating abilities. In addition, granulocyte colony-stimulating factor -induced mobilization of HSPCs was significantly decreased by specific CB₂ antagonists and was impaired in Cnr2(-/-) cannabinoid type 2 receptor knockout mice. Taken together, these results demonstrate that the endocannabinoid system is involved in hematopoiesis and that CB₂/CB₂ agonist axis mediates repopulation of hematopoiesis and mobilization of HSPCs. Thus, CB₂ agonists may be therapeutically applied in clinical conditions, such as bone marrow transplantation.

Endocannabinoids are expressed in bone marrow stromal niches and play a role in interactions of hematopoietic stem and progenitor cells with the bone marrow microenvironment

Endocannabinoids are lipid signaling molecules that act via G-coupled receptors, CB(1) and CB(2). The endocannabinoid system is capable of activation of distinct signaling pathways on demand in response to pathogenic events or stimuli, hereby enhancing cell survival and promoting tissue repair. However, the role of endocannabinoids in hematopoietic stem and progenitor cells (HSPCs) and their interaction with hematopoietic stem cells (HSC) niches is not known. HSPCs are maintained in the quiescent state in bone marrow (BM) niches by intrinsic and extrinsic signaling. We report that HSPCs express the CB(1) receptors and that BM stromal cells secrete endocannabinoids, anandamide (AEA) (35 pg/10(7) cells), and 2-AG (75.2 ng/10(7) cells). In response to the endotoxin lipopolysaccharide (LPS), elevated levels of AEA (75.6 pg/10(7) cells) and 2-AG (98.8 ng/10(7) cells) were secreted from BM stromal cells, resulting in migration and trafficking of HSPCs from the BM niches to the peripheral blood. Furthermore, administration of exogenous cannabinoid CB(1) agonists in vivo induced chemotaxis, migration, and mobilization of human and murine HSPCs. Cannabinoid receptor knock-out mice Cnr1(-/-) showed a decrease in side population (SP) cells, whereas fatty acid amide hydrolase (FAAH)(-/-) mice, which have elevated levels of AEA, yielded increased colony formation as compared with WT mice. In addition, G-CSF-induced mobilization in vivo was modulated by endocannabinoids and was inhibited by specific cannabinoid antagonists as well as impaired in cannabinoid receptor knock-out mice Cnr1(-/-), as compared with WT mice. Thus, we propose a novel function of the endocannabinoid system, as a regulator of HSPC interactions with their BM niches, where endocannabinoids are expressed in HSC niches and under stress conditions, endocannabinoid expression levels are enhanced to induce HSPC migration for proper hematopoiesis.

Endocannabinoids and pregnancy

Acylethanolamides such as anandamide (AEA), and monoacylglycerols like 2-arachidonoylglycerol are endocannabinoids that bind to cannabinoid, vanilloid and peroxisome proliferator-activated receptors. These compounds, their various receptors, the purported membrane transporter(s), and related enzymes that synthesize and degrade them are collectively referred to as the "endocannabinoid system (ECS)". Poorly defined cellular and molecular mechanisms control the biological actions of the ECS. Over the last decade evidence has been emerging to suggest that the ECS plays a significant role in various aspects of human reproduction. In this review, we summarize our current understanding of this role especially the involvement of AEA and related ECS elements in regulating oogenesis, embryo oviductal transport, blastocyst implantation, placental development and pregnancy outcomes, and sperm survival, motility, capacitation and acrosome reaction. Additionally, the possibility that plasma and tissue AEA and other cannabinoids may represent reliable diagnostic markers of natural and assisted reproduction and pregnancy outcomes in women will be discussed.

Immunoactive effects of cannabinoids: considerations for the therapeutic use of cannabinoid receptor agonists and antagonists

The active constituents of Cannabis sativa have been used for centuries as recreational drugs and medicinal agents. Today, marijuana is the most prevalent drug of abuse in the United States and, conversely, therapeutic use of marijuana constituents are gaining mainstream clinical and political acceptance. Given the documented contributions of endocannabinoid signaling to a range of physiological systems, including cognitive function, and the control of eating behaviors, it is unsurprising that cannabinoid receptor agonists and antagonists are showing significant clinical potential. In addition to the neuroactive effects of cannabinoids, an emerging body of data suggests that both endogenous and exogenous cannabinoids are potently immunoactive. The central premise of this review article is that the immunological effects of cannabinoids should be considered in the context of each prescribing decision. We present evidence that the immunological effects of cannabinoid receptor agonists and antagonists are highly relevant to the spectrum of disorders for which cannabinoid therapeutics are currently offered.

Cannabinoid receptor type 1- and 2-mediated increase in cyclic AMP inhibits T cell receptor-triggered signaling

The aim of this study was to characterize inhibitory mechanisms on T cell receptor signaling mediated by the cannabinoid receptors CB1 and CB2. Both receptors are coupled to G(i/o) proteins, which are associated with inhibition of cyclic AMP formation. In human primary and Jurkat T lymphocytes, activation of CB1 by R(+)-methanandamide, CB2 by JWH015, and both by Delta9-tetrahydrocannabinol induced a short decrease in cyclic AMP lasting less than 1 h. However, this decrease was followed by a massive (up to 10-fold) and sustained (at least up to 48 h) increase in cyclic AMP. Mediated by the cyclic AMP-activated protein kinase A and C-terminal Src kinase, the cannabinoids induced a stable phosphorylation of the inhibitory Tyr-505 of the leukocyte-specific protein tyrosine kinase (Lck). By thus arresting Lck in its inhibited form, the cannabinoids prevented the dephosphorylation of Lck at Tyr-505 in response to T cell receptor activation, which is necessary for the subsequent initiation of T cell receptor signaling. In this way the cannabinoids inhibited the T cell receptor-triggered signaling, i.e. the activation of the zeta-chain-associated protein kinase of 70 kDa, the linker for activation of T cells, MAPK, the induction of interleukin-2, and T cell proliferation. All of the effects of the cannabinoids were blocked by the CB1 and CB2 antagonists AM281 and AM630. These findings help to better understand the immunosuppressive effects of cannabinoids and explain the beneficial effects of these drugs in the treatment of T cell-mediated autoimmune disorders like multiple sclerosis.

Modulation of cannabinoid receptor activation as a neuroprotective strategy for EAE and stroke

Recognition of the importance of the endocannabinoid system in both homeostasis and pathologic responses raised interest recently in the development of therapeutic agents based on this system. The CB(2) receptor, a component of the endocannabinoid system, has significant influence on immune function and inflammatory responses. Inflammatory responses are major contributors to central nervous system (CNS) injury in a variety of diseases. In this report, we present evidence that activation of CB(2) receptors, by selective CB(2) agonists, reduces inflammatory responses that contribute to CNS injury. The studies demonstrate neuroprotective effects in experimental autoimmune encephalomyelitis, a model of multiple sclerosis, and in a murine model of cerebral ischemia/reperfusion injury. In both cases, CB(2) receptor activation results in reduced white cell rolling and adhesion to cerebral microvessels, a reduction in immune cell invasion, and improved neurologic function after insult. In addition, administration of the CB(1) antagonist SR141716A reduces infarct size following ischemia/reperfusion injury. Administration of both a selective CB(2) agonist and a CB(1) antagonist has the unique property of increasing blood flow to the brain during the occlusion period, suggesting an effect on collateral blood flow. In summary, selective CB(2) receptor agonists and CB(1) receptor antagonists have significant potential for neuroprotection in animal models of two devastating diseases that currently lack effective treatment options.

The endocannabinoid anandamide from immunomodulation to neuroprotection. Implications for multiple sclerosis

Over the last decade, the endocannabinoid system (ECS) has emerged as a potential target for multiple sclerosis (MS) management. A growing amount of evidence suggests that cannabinoids may be neuroprotective during CNS inflammation. Advances in the understanding of the physiology and pharmacology of the ECS have potentiated the interest of several components of this system as useful biological targets for disease management. Alterations of the ECS have been recently implicated in a number of neuroinflammatory and neurodegenerative conditions, so that the pharmacological modulation of cannabinoid (CB) receptors and/or of the enzymes controlling synthesis, transport, and degradation of these lipid mediators is considered an option to treat several neurological diseases. This chapter focuses on our current understanding of the function of anandamide (AEA), its biological and therapeutic implications, as well as a description of its effects on neuroimmune modulation.

Gastrointestinal endocannabinoid system: multifaceted roles in the healthy and inflamed intestine

1. The endogenous cannabinoid (endocannabinoid) system is emerging as a key modulator of intestinal physiology, influencing motility, secretion, epithelial integrity and immune function in the gut, in addition to influencing satiety and emesis. 2. Accumulating evidence suggests that the endocannabinoid system may play a pivotal role in the pathophysiology of gastrointestinal disease, particularly in the light of recent studies demonstrating an effect of endocannabinoids on the development of experimental inflammation and linkages with functional clinical disorders characterized by altered motility. 3. The predominant endocannabinoids, anandamide and 2-arachidonoylglycerol, not only mediate their effects via two recognized cannabinoid receptor subtypes, namely CB(1) and CB(2), but emerging evidence now shows they are also substrates for cyclo-oxygenase (COX)-2, generating a distinct and novel class of prostaglandin ethanolamides (prostamides) and prostaglandin glycerol esters. These compounds are bioactive and may mediate an array of biological effects distinct to those of conventional prostanoids. 4. The effects of prostamides on gastrointestinal motility, secretion, sensation and immune function have not been characterized extensively. Prostamides may play an important role in gastrointestinal inflammation, particularly given the enhanced expression of both COX-2 and endocannabinoids that occurs in the inflamed gut. 5. Further preclinical studies are needed to determine the therapeutic potential of drugs targeting the endocannabinoid system in functional and inflammatory gut disorders, to assist with the determination of feasibility for clinical translation.

Recreational drug use and T lymphocyte subpopulations in HIV-uninfected and HIV-infected men

The effects of recreational drugs on CD4 and CD8 T cells in humans are not well understood. We conducted a longitudinal analysis of men who have sex with men (MSM) enrolled in the Multicenter AIDS Cohort Study (MACS) to define associations between self-reported use of marijuana, cocaine, poppers and amphetamines, and CD4 and CD8 T cell parameters in both HIV-uninfected and HIV-infected MSM. For the HIV-infected MSM, we used clinical and laboratory data collected semiannually before 1996 to avoid potential effects of antiretroviral treatment. A regression model that allowed random intercepts and slopes as well as autoregressive covariance structure for within subject errors was used. Potential confounders adjusted for included length of follow-up, demographics, tobacco smoking, alcohol use, risky sexual behaviors, history of sexually transmitted infections, and antiviral therapy. We found no clinically meaningful associations between use of marijuana, cocaine, poppers, or amphetamines and CD4 and CD8 T cell counts, percentages, or rates of change in either HIV-uninfected or -infected men. The regression coefficients were of minimum magnitude despite some reaching statistical significance. No threshold effect was detected for frequent (at least weekly) or continuous substance use in the previous year. These results indicate that use of these substances does not adversely affect the numbers and percentages of circulating CD4 or CD8 T cells in either HIV-uninfected or -infected MSM.

Analysis of promoter regions regulating basal and interleukin-4-inducible expression of the human CB1 receptor gene in T lymphocytes

The majority of effects of cannabinoids are mediated by the two receptors CB1 and CB2. In addition to neuronal cells, CB1 receptors are expressed in T lymphocytes, in which they are involved in cannabinoid-induced T helper cell biasing. Although basally expressed only weakly in T cells, CB1 receptors are up-regulated in these cells by stimuli such as cannabinoids themselves. This effect is mediated by interleukin-4. In this study, we investigated basal and interleukin-4-inducible expression of the CB1 gene in T lymphocytes. In a promoter analysis, two regions [nucleotides (nts) -3086 to -2490 and nts -1950 to -1653] were identified, which suppress basal transcription of the gene in Jurkat T cells, whereas the region between nts -648 and -559 enhanced basal CB1 transcription. Interleukin-4 markedly induced transcription of CB1 in Jurkat cells and primary human T cells. Experiments using transcription factor decoy oligonucleotides demonstrated that STAT6 mediates regulation of the gene by interleukin-4. Using reporter gene assays and the transcription factor decoy oligonucleotide approach, a binding site for STAT6 was identified at nt -2769 on the human CB1 gene promoter. Interleukin-4 also caused up-regulation of functional CB1 receptor proteins. In interleukin-4 pretreated, but not in naive Jurkat cells, the CB1 agonist R(+)-methanandamide caused a significant inhibition of forskolin-induced cAMP formation. This effect was blocked by the CB1-selective antagonists N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251) and 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-4-mo rpholinyl-1H-pyrazole-3-carboxamide (AM281). Taken together, these data show that CB1 receptors are expressed and up-regulated by interleukin-4 in T lymphocytes, which enables CB1-mediated communication to cells of other systems, such as neuronal cells.

The peripheral cannabinoid receptor knockout mice: an update

This review gives an overview of the CB2 receptor (CB2R) knockout (CB2R-/-) mice phenotype and the work that has been carried out using this mutant mouse. Using the CB2R-/- mice, investigators have discovered the involvement of CB2R on immune cell function and development, infection, embryonic development, bone loss, liver disorders, pain, autoimmune inflammation, allergic dermatitis, atherosclerosis, apoptosis and chemotaxis. Using the CB2R-/- mice, investigators have also found that this receptor is not involved in cannabinoid-induced hypotension. In addition, the CB2R-/- mice have been used to determine specific tissue CB2R expression. The specificity of synthetic cannabinoid agonists, antagonists and anti-CB2R antibodies has been screened using tissues from CB2R-/- mice. Thus, the use of this mouse model has greatly helped reveal the diverse events involving the CB2R, and has aided in drug and antibody screening.

Direct suppression of autoreactive lymphocytes in the central nervous system via the CB2 receptor

The cannabinoid system is now recognized as a regulator of both the nervous and immune systems. Although marijuana has been used for centuries for the treatment of a variety of disorders, its therapeutic mechanisms are only now being understood. The best-studied plant cannabinoid, delta9-tetrahydrocannabinol (THC), produced by Cannabis sativa and found in marijuana, has shown evidence of being immunosuppressive in both in vivo and in vitro. Since THC binds to at least two receptors that are differentially expressed by the immune and nervous systems, it has not been possible to clearly discriminate the biological effects it exerts in the two systems. In addition, endogenous cannabinoids have also been described that bind to both receptors and exert both neuronal and immune modulatory activity. The generation of mice deficient in specific cannabinoid receptors has facilitated studies to discriminate cannabinoid-specific functions. This review focuses on the function of the cannabinoid receptor 2 (CB2), primarily expressed in the immune system, in regulating T cell effector functions associated with autoimmune inflammation in the central nervous system (CNS).

Combined immunomodulating properties of 3,4-methylenedioxymethamphetamine (MDMA) and cannabis in humans

AIMS

Cell-mediated immune function and the occurrence of mild infectious diseases was investigated. Participants Polydrug consumers of 3,4-methylenedioxymethamphetamine (MDMA) and cannabis (n = 37) compared to cannabis users only (n = 23) and control group (n = 34).

DESIGN

A longitudinal prospective study with three cross-sectional evaluations at time 0 and at 6 months and 1 year was performed.

FINDINGS

At baseline, a significant decrease in interleukin (IL)-2 and an increase in anti-inflammatory transforming growth factor (TGF)-beta1, together with a decrease in the number of total lymphocytes, CD4 and natural killer (NK) cells were observed in the MDMA-cannabis group, with intermediate alterations in the cannabis group. Immune alterations observed at baseline were sustained over time. No differences were found between regular and occasional MDMA users. A significantly higher rate of mild infections in regular MDMA-cannabis users compared with occasional MDMA-cannabis users and the remaining groups was observed.

CONCLUSIONS

The present data confirm that long-term alterations in immunological homeostasis may result in general health status impairment and subsequent increased susceptibility to infection and immune-related disorders.

Anti-inflammatory property of the cannabinoid receptor-2-selective agonist JWH-133 in a rodent model of autoimmune uveoretinitis

Previous studies have shown that cannabinoids have anti-inflammatory and immune-modulating effects, but the precise mechanisms of action remain to be elucidated. In this study, we investigated the effect of JWH 133, a selective agonist for cannabinoid receptor 2, the main receptor expressed on immune cells, in a model of autoimmune disease, experimental autoimmune uveoretinitis (EAU). JWH 133 suppressed EAU in a dose-dependent manner (0.015-15 mg/kg), and the suppressive effect could be achieved in the disease-induction stage and the effector stage. Leukocytes from mice, which had been treated with JWH 133, had diminished responses to retinal peptide and mitogen Con A stimulation in vitro. In vivo JWH 133 treatment also abrogated leukocyte cytokine/chemokine production. Further in vitro studies indicated that JWH 133 down-regulated the TLR4 via Myd88 signal transduction, which may be responsible for its moderate, suppressive effect on antigen presentation. In vivo JWH 133 treatment (1 mg/kg) also suppressed leukocyte trafficking (rolling and infiltration) in inflamed retina as a result of an effect on reducing adhesion molecules CD162 (P-selectin glycoprotein ligand 1) and CD11a (LFA-1) expression on T cells. In conclusion, the cannabinoid agonist JWH 133 has a high in vivo, anti-inflammatory property and may exert its effect via inhibiting the activation and function of autoreactive T cells and preventing leukocyte trafficking into the inflamed tissue.

Local administration of WIN 55,212-2 reduces chronic granuloma-associated angiogenesis in rat by inhibiting NF-κB activation

Chronic inflammation is often associated with granuloma formation that is a hallmark of many human diseases. The transcription factor nuclear factor-kappa B (NF-kappaB) plays a central role in this process by regulating the expression of several pro-inflammatory genes. Cannabinoids (CBs) from Cannabis sativa L. exert a large number of biological effects including anti-inflammatory and anti-angiogenic effects. In this study, we investigated the role of CBs on granuloma formation induced by lambda-carrageenin-soaked sponge implant in rat. Our results show that local administration of WIN 55,212-2, a CB(1)/CB(2) agonist, given daily or at time of implantation significantly decreased weight and neo-angiogenesis in granuloma tissue and inhibited nuclear factor-kappa B (NF-kappaB)/DNA binding that was associated with a reduced inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), tumor necrosis factor alpha (TNF-alpha), and vascular endothelial growth factor (VEGF) messenger RNA (mRNA) and protein expression. Also, arachidonyl-2-chloroethylamide (ACEA), a CB(1) selective agonist, and JWH-015, a CB(2) selective agonist, exhibited the same effects that were reversed by SR141716-A and SR144528, respectively, CB(1) and CB(2) selective antagonists. These results indicate that CBs given locally may represent a potential therapeutic tool in controlling chronic inflammation avoiding psychotropic effects.

Overactivity of the intestinal endocannabinoid system in celiac disease and in methotrexate-treated rats

The endocannabinoid system is upregulated in both human inflammatory bowel diseases and experimental models of colitis. In this study, we investigated whether this upregulation is a marker also of celiac disease-induced atrophy. The levels of the cannabinoid CB(1) receptor, of the endocannabinoids, anandamide, and 2-arachidonoyl-glycerol (2-AG), and of the anti-inflammatory mediator palmitoylethanolamide (PEA) were analyzed in bioptic samples from the duodenal mucosa of celiac patients at first diagnosis assessed by the determination of antiendomysial antibodies and histological examination. Samples were analyzed during the active phase of atrophy and after remission and compared to control samples from non-celiac patients. The levels of anandamide and PEA were significantly elevated (approx. 2- and 1.8-fold, respectively) in active celiac patients and so were those of CB(1) receptors. Anandamide levels returned to normal after remission with a gluten-free diet. We also analyzed endocannabinoid and PEA levels in the jejunum of rats 2, 3, and 7 days after treatment with methotrexate, which causes inflammatory features (assessed by histopathological analyses and myeloperoxidase activity) similar to those of celiac patients. In both muscle/serosa and mucosa layers, the levels of anandamide, 2-AG, and PEA peaked 3 days after treatment and returned to basal levels at remission, 7 days after treatment. Thus, intestinal endocannabinoid levels peak with atrophy and regress with remission in both celiac patients and methotrexate-treated rats. The latter might be used as a model to study the role of the endocannabinoid system in celiac disease.

Activation of human T cells induces upregulation of cannabinoid receptor type 1 transcription

OBJECTIVE

Effects of cannabinoids are mediated by CB1 and CB2 receptors. In addition to neuronal effects, cannabinoids are potent modulators of immune functions. In this report, we investigated whether the transcription of these receptors is regulated after activation of T lymphocytes.

METHODS

CB1- and CB2-specific mRNA of primary human peripheral blood T cells and cells of the human T cell line Jurkat was measured by quantitative real-time RT-PCR in response to CD3/28. Using the decoy oligonucleotide approach, transcription factors involved in the regulation were determined. A promoter analysis was performed using transient transfection of chloramphenicol acetyl transferase reporter gene constructs in Jurkat cells.

RESULTS

Activation of human T cells caused an induction of CB1 mRNA expression in primary human T cells (8-fold) and Jurkat cells (29-fold). In contrast, CB2 transcription was not regulated. The CD3/28-mediated upregulation of CB1 involves the transcription factors AP-1, NF kappaB and NFAT. Furthermore, 2,490 bp of the CB1 promoter mediated inducibility in response to CD3/28.

CONCLUSIONS

The upregulation of CB1 in activated T cells, together with the constitutive expression of CB2, enables cellular responses to cannabinoids mediated by both receptor subtypes. It may thus contribute to the understanding of the various modulatory effects of cannabinoids on activated T cells.

Cannabinoids inhibit human keratinocyte proliferation through a non-CB1/CB2 mechanism and have a potential therapeutic value in the treatment of psoriasis

BACKGROUND

Cannabinoids from cannabis (Cannabis sativa) are anti-inflammatory and have inhibitory effects on the proliferation of a number of tumorigenic cell lines, some of which are mediated via cannabinoid receptors. Cannabinoid (CB) receptors are present in human skin and anandamide, an endogenous CB receptor ligand, inhibits epidermal keratinocyte differentiation. Psoriasis is an inflammatory disease also characterised in part by epidermal keratinocyte hyper-proliferation.

OBJECTIVE

We investigated the plant cannabinoids Delta-9 tetrahydrocannabinol, cannabidiol, cannabinol and cannabigerol for their ability to inhibit the proliferation of a hyper-proliferating human keratinocyte cell line and for any involvement of cannabinoid receptors.

METHODS

A keratinocyte proliferation assay was used to assess the effect of treatment with cannabinoids. Cell integrity and metabolic competence confirmed using lactate-dehydrogenase and adenosine tri-phosphate assays. To determine the involvement of the receptors, specific agonist and antagonist were used in conjunction with some phytocannabinoids. Western blot and RT-PCR analysis confirmed presence of CB1 and CB2 receptors.

RESULTS

The cannabinoids tested all inhibited keratinocyte proliferation in a concentration-dependent manner. The selective CB2 receptor agonists JWH015 and BML190 elicited only partial inhibition, the non-selective CB agonist HU210 produced a concentration-dependent response, the activity of theses agonists were not blocked by either CB1/CB2 antagonists.

CONCLUSION

The results indicate that while CB receptors may have a circumstantial role in keratinocyte proliferation, they do not contribute significantly to this process. Our results show that cannabinoids inhibit keratinocyte proliferation, and therefore support a potential role for cannabinoids in the treatment of psoriasis.