Signaling through cannabinoid receptor 2 suppresses murine dendritic cell migration by inhibiting matrix metalloproteinase 9 expression

Proteolytic Vesicles Derived from Salmonella enterica Serovar Typhimurium-Infected Macrophages: Enhancing MMP-9-Mediated Invasion and EV Accumulation

Proteolysis of the extracellular matrix (ECM) by matrix metalloproteinases (MMPs) plays a crucial role in the immune response to bacterial infections. Here we report the secretion of MMPs associated with proteolytic extracellular vesicles (EVs) released by macrophages in response to Salmonella enterica serovar Typhimurium infection. Specifically, we used global proteomics, in vitro, and in vivo approaches to investigate the composition and function of these proteolytic EVs. Using a model of S. Typhimurium infection in murine macrophages, we isolated and characterized a population of small EVs. Bulk proteomics analysis revealed significant changes in protein cargo of naïve and S. Typhimurium-infected macrophage-derived EVs, including the upregulation of MMP-9. The increased levels of MMP-9 observed in immune cells exposed to S. Typhimurium were found to be regulated by the toll-like receptor 4 (TLR-4)-mediated response to bacterial lipopolysaccharide. Macrophage-derived EV-associated MMP-9 enhanced the macrophage invasion through Matrigel as selective inhibition of MMP-9 reduced macrophage invasion. Systemic administration of fluorescently labeled EVs into immunocompromised mice demonstrated that EV-associated MMP activity facilitated increased accumulation of EVs in spleen and liver tissues. This study suggests that macrophages secrete proteolytic EVs to enhance invasion and ECM remodeling during bacterial infections, shedding light on an essential aspect of the immune response.

Exploration of the immuno-adjuvant effect and mechanism of Anemoside B4 through network pharmacology and experiment verification

BACKGROUND

Extensive investigation has been undertaken about the utilization of saponin adjuvants in vaccines intended for veterinary and human applications. AB4 is the main constituent of the traditional Chinese medicine, Pulsatilla chinensis (Bunge) Regel, and has immunomodulatory activity. However, there is a paucity of reports on AB4 as a potential adjuvant.

PURPOSE

The objective of this work was to clarify the adjuvant role of AB4 and the molecular mechanisms that underlie its immunomodulatory actions.

STUDY DESIGN AND METHODS

The immunomodulatory effects of AB4 were investigated using network pharmacological analyses. These effects were validated by evaluating the developmental status of the immune organs and by using the following techniques: ELISA for the quantification of serum-specific antibodies to determine immune-related cytokine levels; the MTS method for the assessment of proliferative activity of splenic lymphocytes; flow cytometry to analyze lymphocyte and dendritic cell activation status; and western blotting for mechanistic analysis at the protein level.

RESULTS

The network pharmacological analysis predicted a total of 52 targets and 12 pathways for AB4 to exert immunomodulatory effects. In a mouse model with immunity to OVA, the introduction of AB4 resulted in the enhancement of immunological organ growth and maturation, elevation of blood antibodies targeting OVA, and amplification of the production of cytokines associated with Th1 and Th2 immune responses. Additionally, the administration of AB4 resulted in a notable augmentation of lymphocyte proliferation and an elevation in the CD4+/CD8+ T lymphocyte ratios. Furthermore, the administration of AB4 enhanced the maturation process of DCs in the draining LNs and increased the production of co-stimulatory factors and MHC II molecules. AB4 induces the upregulation of TLR4 and IKK proteins, as well as the phosphorylation of NF-κB p65 protein within the TLR4/NF-κB signaling cascade, while concurrently suppressing the expression of IκBα protein.

CONCLUSION

The specific immunoadjuvant effects of AB4 have been demonstrated to modulate the growth and maturation of immune organs and enhance the secretion and cellular activity of pertinent immune molecules. The utilization of network pharmacology, combined within and in vivo vitro assays, clarified the adjuvant function of AB4, which potentially involves the regulation of the TLR4/NF-κB signaling pathway.

Imaging and Genetic Tools for the Investigation of the Endocannabinoid System in the CNS

As central nervous system (CNS)-related disorders present an increasing cause of global morbidity, mortality, and high pressure on our healthcare system, there is an urgent need for new insights and treatment options. The endocannabinoid system (ECS) is a critical network of endogenous compounds, receptors, and enzymes that contribute to CNS development and regulation. Given its multifaceted involvement in neurobiology and its significance in various CNS disorders, the ECS as a whole is considered a promising therapeutic target. Despite significant advances in our understanding of the ECS's role in the CNS, its complex architecture and extensive crosstalk with other biological systems present challenges for research and clinical advancements. To bridge these knowledge gaps and unlock the full therapeutic potential of ECS interventions in CNS-related disorders, a plethora of molecular-genetic tools have been developed in recent years. Here, we review some of the most impactful tools for investigating the neurological aspects of the ECS. We first provide a brief introduction to the ECS components, including cannabinoid receptors, endocannabinoids, and metabolic enzymes, emphasizing their complexity. This is followed by an exploration of cutting-edge imaging tools and genetic models aimed at elucidating the roles of these principal ECS components. Special emphasis is placed on their relevance in the context of CNS and its associated disorders.

Role of the endocannabinoid system in the pathophysiology of endometriosis and therapeutic implications

Endometriosis patients experience debilitating chronic pain, and the first-line treatment is ineffective at managing symptoms. Although surgical removal of the lesions provides temporary relief, more than 50% of the patients experience disease recurrence. Despite being a leading cause of hysterectomy, endometriosis lacks satisfactory treatments and a cure. Another challenge is the poor understanding of disease pathophysiology which adds to the delays in diagnosis and overall compromised quality of life. Endometriosis patients are in dire need of an effective therapeutic strategy that is both economical and effective in managing symptoms, while fertility is unaffected. Endocannabinoids and phytocannabinoids possess anti-inflammatory, anti-nociceptive, and anti-proliferative properties that may prove beneficial for endometriosis management, given that inflammation, vascularization, and pain are hallmark features of endometriosis. Endocannabinoids are a complex network of molecules that play a central role in physiological processes including homeostasis and tissue repair, but endocannabinoids have also been associated in the pathophysiology of several chronic inflammatory diseases including endometriosis and cancers. The lack of satisfactory treatment options combined with the recent legalization of recreational cannabinoids in some parts of the world has led to a rise in self-management strategies including the use of cannabinoids for endometriosis-related pain and other symptoms. In this review, we provide a comprehensive overview of endocannabinoids with a focus on their potential roles in the pathophysiology of endometriosis. We further provide evidence-driven perspectives on the current state of knowledge on endometriosis-associated pain, inflammation, and therapeutic avenues exploiting the endocannabinoid system for its management.

The Synthetic Cannabinoid URB447 Exerts Antitumor and Antimetastatic Effect in Melanoma and Colon Cancer

The endocannabinoid system is widespread through the body and carries out a wide variety of functions. However, its involvement in other pathologies, such as cancer, still needs further attention. We aim to investigate the role of CB2 receptor during melanoma and colorectal cancer (CRC) aggressiveness and metastatic growth in the liver. We used the synthetic cannabinoid URB447, a known CB2 agonist and CB1 antagonist drug, and studied prometastatic ability of mouse B16 melanoma and MCA38 CRC cells, by means of proliferation, apoptosis, cell cycle, migration and matrix degradation in vitro upon URB447 treatment. We reported a dose-dependent viability decrease in both tumor types. This result is partly mediated by apoptotic cell death and cell cycle arrest in G1/G0 phase, as observed through flow cytometry. Melanoma and CRC cell migration was affected in a dose-dependent fashion as observed through scratch assay, whereas the secretion of matrix degrading proteins metalloprotease 2 (MMP2) and 9 (MMP9) in tumor cells did not significantly change. Moreover, daily treatment of tumor bearing mice with URB447 decreased the development of liver metastasis in a melanoma model in vivo. This proof of concept study points out to the synthetic cannabinoid URB447 as a potential candidate for deeper studies to confirm its potential as antitumor therapy and liver metastasis treatment for CRC and melanoma.

Cannabinoid receptors in the inflammatory cells of canine atopic dermatitis

Background

Atopic dermatitis (AD) is one of the most common cutaneous inflammatory and pruritic diseases in dogs. Considering its multifactorial nature, AD can be a challenging disease to manage, and the therapeutic strategy must often be multimodal. In recent years, research has been moving toward the use of natural products which have beneficial effects on inflammation and itching, and no side effects. Cannabinoid receptors have been demonstrated to be expressed in healthy and diseased skin; therefore, one of the potential alternative therapeutic targets for investigating AD is the endocannabinoid system (ECS).

Objective

To immunohistochemically investigate the expression of the cannabinoid receptor type 2 (CB2R), and the cannabinoid-related receptors G protein-coupled receptor 55 (GPR55), transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) in mast cells (MCs), macrophages, dendritic cells (DCs), T cells, and neutrophils of the skin of dogs with AD.

Animals

Samples of skin tissues were collected from eight dogs with AD (AD-dogs).

Materials and methods

The immunofluorescent stained cryosections of the skins of 8 dogs with AD having antibodies against CB2R, GPR55, TRPV1, TRPA1 were semiquantitatively evaluated. The inflammatory cells were identified using antibodies against tryptase (mast cells), ionized calcium binding adaptor molecule 1 (IBA1) (macrophages/DCs), CD3 (T cells), and calprotectin (neutrophils). The proportions of MCs, macrophages/DCs, T cells, and neutrophils expressing CB2R, GPR55, TRPV1 and TRPA1 were evaluated.

Results

The cells of the inflammatory infiltrate showed immunoreactivity (IR) for all or for some of the cannabinoid and cannabinoid-related receptors studied. In particular, MCs and macrophages/DCs showed CB2R-, GPR55-, TRPA1-, and TRPV1-IR; T cells showed CB2R-, GPR55- and TRPA1-IR, and neutrophils expressed GPR55-IR. Co-localization studies indicated that CB2R-IR was co-expressed with TRPV1-, TRPA1-, and GPR55-IR in different cellular elements of the dermis of the AD-dogs.

Conclusions and clinical importance

Cannabinoid receptor 2, and cannabinoid-related receptors GPR55, TRPV1 and TRPA1 were widely expressed in the inflammatory infiltrate of the AD-dogs. Based on the present findings, the ECS could be considered to be a potential therapeutic target for dogs with AD, and may mitigate itch and inflammation.

Cannabis suppresses antitumor immunity by inhibiting JAK/STAT signaling in T cells through CNR2

The combination of immune checkpoint blockade (ICB) with chemotherapy significantly improves clinical benefit of cancer treatment. Since chemotherapy is often associated with adverse events, concomitant treatment with drugs managing side effects of chemotherapy is frequently used in the combination therapy. However, whether these ancillary drugs could impede immunotherapy remains unknown. Here, we showed that ^∆9-tetrahydrocannabinol (THC), the key ingredient of drugs approved for the treatment of chemotherapy-caused nausea, reduced the therapeutic effect of PD-1 blockade. The endogenous cannabinoid anandamide (AEA) also impeded antitumor immunity, indicating an immunosuppressive role of the endogenous cannabinoid system (ECS). Consistently, high levels of AEA in the sera were associated with poor overall survival in cancer patients. We further found that cannabinoids impaired the function of tumor-specific T cells through CNR2. Using a knock-in mouse model expressing a FLAG-tagged Cnr2 gene, we discovered that CNR2 binds to JAK1 and inhibits the downstream STAT signaling in T cells. Taken together, our results unveiled a novel mechanism of the ECS-mediated suppression on T-cell immunity against cancer, and suggest that cannabis and cannabinoid drugs should be avoided during immunotherapy.

Cannabinoids, their cellular receptors, and effects on the invasive phenotype of carcinoma and metastasis

BACKGROUND

The morbidity and mortality of cancer are significantly impacted by the invasive and metastatic potential of particular subgroups of malignant cells within a tumor. The particular pre-metastatic properties of cancerous cells are thus a critical target for novel therapeutics in the oncology field. Cannabinoid molecules have been investigated in recent years in the context of invasion and metastasis of various malignancies, with varying effects reported in the literature.

RECENT FINDINGS

There was substantial variability in the findings reported by the literature of the effects of cannabinoid molecules on cancer cell invasion and metastasis. These effects varied depending on which ligand and which of the CB1, CB2, or GPR55 receptors were investigated. These findings suggest a role for the phenomenon of biased signaling in explaining the diversity of effects of cannabinoid molecules on cancer cell invasion.

CONCLUSION

While substantially more investigation is required into the effects of cannabinoid molecules on cancer cell invasion and metastasis, we describe in this review the significant diversity in the responses of cancer cells to cannabinoid molecules in terms of their invasive and metastatic capacities.

Cannabinoid type 2 receptor (CB2R) distribution in dermatomyositis skin and peripheral blood mononuclear cells (PBMCs) and in vivo effects of LenabasumTM

Background

Lenabasum is a cannabinoid type 2 receptor (CB2R) reverse agonist that demonstrates anti-inflammatory effects in vivo and in vitro in dermatomyositis (DM) and is currently being investigated for therapeutic potential. The purpose of our study is to investigate CB2R distribution as well as the effects of lenabasum in DM.

Methods

Immunohistochemistry staining (IHC) was utilized to examine immune cell and cytokine production changes in lesional DM skin biopsies from lenabasum and placebo-treated patients. CB2R expression in various immune cell populations within DM skin was investigated with image mass cytometry (IMC), whereas flow cytometry elucidated CB2R expression in DM peripheral blood mononuclear cells (PBMCs) as well as cytokine production by CB2R-expressing cell populations.

Results

After 12 weeks of lenabasum treatment, IHC staining showed that CD4+ T cells, CB2R, IL-31, IFN-γ, and IFN-β cytokines were downregulated. IFN-γ and IFN-β mRNA decreased in lesional DM skin but not in PBMCs. IMC findings revealed that CB2R was upregulated in DM lesional skin compared to HC skin and DM PBMCs (p<0.05). In DM skin, CB2R was upregulated on dendritic cells, B cells, T cells, and macrophages while dendritic cells had the greatest expression in both DM skin and PBMCs (p<0.05). These CB2R+ cells in the skin produce IL-31, IL-4, IFN-γ, and IFN-β.

Conclusion

Our findings of differential CB2R expression based on location and cell type suggest modes by which lenabasum may exert anti-inflammatory effects in DM and highlights dendritic cells as potential therapeutic targets.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02665-x.

Potentiation of microglial endocannabinoid signaling alleviates neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) isaprogressive neurodegenerative disorder characterized by chronic inflammation due to the presence of neurotoxic Aβ and tau proteins. Increased microglial activation and inflated immune response are the other factors to be considered in AD pathology. Microglial cells own biochemical machinery that synthesizes and release endocannabinoids. The exploitation of therapeutic actions of endocannabinoid system has newly emerged in the field of Alzheimer's disease. The activation of cannabinoid receptors/ cannabinoid system modulates inflammatory responses. This review assesses the association between the microglial endocannabinoid system and neuroinflammation in AD. The data supporting the anti-inflammatory role of pharmacological agents modulating cannabinoid system are also reviewed.

A Synthetic Hydrogel, VitroGel® ORGANOID-3, Improves Immune Cell-Epithelial Interactions in a Tissue Chip Co-Culture Model of Human Gastric Organoids and Dendritic Cells

Immunosurveillance of the gastrointestinal epithelium by mononuclear phagocytes (MNPs) is essential for maintaining gut health. However, studying the complex interplay between the human gastrointestinal epithelium and MNPs such as dendritic cells (DCs) is difficult, since traditional cell culture systems lack complexity, and animal models may not adequately represent human tissues. Microphysiological systems, or tissue chips, are an attractive alternative for these investigations, because they model functional features of specific tissues or organs using microscale culture platforms that recreate physiological tissue microenvironments. However, successful integration of multiple of tissue types on a tissue chip platform to reproduce physiological cell-cell interactions remains a challenge. We previously developed a tissue chip system, the gut organoid flow chip (GOFlowChip), for long term culture of 3-D pluripotent stem cell-derived human intestinal organoids. Here, we optimized the GOFlowChip platform to build a complex microphysiological immune-cell-epithelial cell co-culture model in order to study DC-epithelial interactions in human stomach. We first tested different tubing materials and chip configurations to optimize DC loading onto the GOFlowChip and demonstrated that DC culture on the GOFlowChip for up to 20 h did not impact DC activation status or viability. However, Transwell chemotaxis assays and live confocal imaging revealed that Matrigel, the extracellular matrix (ECM) material commonly used for organoid culture, prevented DC migration towards the organoids and the establishment of direct MNP-epithelial contacts. Therefore, we next evaluated DC chemotaxis through alternative ECM materials including Matrigel-collagen mixtures and synthetic hydrogels. A polysaccharide-based synthetic hydrogel, VitroGel®-ORGANOID-3 (V-ORG-3), enabled significantly increased DC chemotaxis through the matrix, supported organoid survival and growth, and did not significantly alter DC activation or viability. On the GOFlowChip, DCs that were flowed into the chip migrated rapidly through the V-ORG matrix and reached organoids embedded deep within the chip, with increased interactions between DCs and gastric organoids. The successful integration of DCs and V-ORG-3 embedded gastric organoids into the GOFlowChip platform now permits real-time imaging of MNP-epithelial interactions and other investigations of the complex interplay between gastrointestinal MNPs and epithelial cells in their response to pathogens, candidate drugs and mucosal vaccines.

Cannabis and Autoimmunity: Possible Mechanisms of Action

Medical cannabis (MC) describes the usually inhaled or ingested use of a cannabis plant or cannabis extract for medicinal purposes. The action of whole cannabis plants is extremely complex because their large number of active compounds not only bind to a plethora of different receptors but also interact with each other both synergistically and otherwise. Renewed interest in the medicinal properties of cannabis has led to increasing research into the practical uses of cannabis derivatives, and it has been found that the endocannabinoid system (particularly CB2 receptor activation) is a possible target for the treatment of inflammatory and the autoimmune diseases related to immune cell activation. However, in vivo findings still lack, creating difficulties in applying translational cannabinoid research to human immune functions. In this review, we summarized the main mechanisms of action of medical cannabis plant especially regarding the immune system and the endocannabinoid system, looking at preliminary clinical data in three most important autoimmune diseases of three different specialities: rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease.

Pros and Cons of the Cannabinoid System in Cancer: Focus on Hematological Malignancies

The endocannabinoid system (ECS) is a composite cell-signaling system that allows endogenous cannabinoid ligands to control cell functions through the interaction with cannabinoid receptors. Modifications of the ECS might contribute to the pathogenesis of different diseases, including cancers. However, the use of these compounds as antitumor agents remains debatable. Pre-clinical experimental studies have shown that cannabinoids (CBs) might be effective for the treatment of hematological malignancies, such as leukemia and lymphoma. Specifically, CBs may activate programmed cell death mechanisms, thus blocking cancer cell growth, and may modulate both autophagy and angiogenesis. Therefore, CBs may have significant anti-tumor effects in hematologic diseases and may synergistically act with chemotherapeutic agents, possibly also reducing chemoresistance. Moreover, targeting ECS might be considered as a novel approach for the management of graft versus host disease, thus reducing some symptoms such as anorexia, cachexia, fatigue, anxiety, depression, and neuropathic pain. The aim of the present review is to collect the state of the art of CBs effects on hematological tumors, thus focusing on the essential topics that might be useful before moving into the clinical practice.

The Role of Extracellular Matrix Components in Inflammatory Bowel Diseases

The remodeling of extracellular matrix (ECM) within the intestine tissues, which simultaneously involves an increased degradation of ECM components and excessive intestinal fibrosis, is a defining trait of the progression of inflammatory bowel diseases (IBDs), which include ulcerative colitis (UC) and Crohn's disease (CD). The increased activity of proteases, especially matrix metalloproteinases (MMPs), leads to excessive degradation of the extracellular matrix and the release of protein and glycoprotein fragments, previously joined with the extracellular matrix, into the circulation. MMPs participate in regulating the functions of the epithelial barrier, the immunological response, and the process of wound healing or intestinal fibrosis. At a later stage of fibrosis during IBD, excessive formation and deposition of the matrix is observed. To assess changes in the extracellular matrix, quantitative measurement of the concentration in the blood of markers dependent on the activity of proteases, involved in the breakdown of extracellular matrix proteins as well as markers indicating the formation of a new ECM, has recently been proposed. This paper describes attempts to use the quantification of ECM components as markers to predict intestinal fibrosis and evaluate the healing process of the gut. The markers which reflect increased ECM degradation, together with the ones which show the process of creating a new matrix during IBD, allow the attainment of important information regarding the changes in the intestinal tissue, epithelial integrity and extracellular matrix remodeling. This paper contains evidence confirming that ECM remodeling is an integral part of directional cell signaling in the progression of IBD, and not only a basis for the ongoing processes.

Delta-9-tetrahydrocannabinol inhibits invasion of HTR8/SVneo human extravillous trophoblast cells and negatively impacts mitochondrial function

Prenatal cannabis use is a significant problem and poses important health risks for the developing fetus. The molecular mechanisms underlying these changes are not fully elucidated but are thought to be attributed to delta-9-tetrahydrocannabinol (THC), the main bioactive constituent of cannabis. It has been reported that THC may target the mitochondria in several tissue types, including placental tissue and trophoblast cell lines, and alter their function. In the present study, in response to 48-h THC treatment of the human extravillous trophoblast cell line HTR8/SVneo, we demonstrate that cell proliferation and invasion are significantly reduced. We further demonstrate THC-treatment elevated levels of cellular reactive oxygen species and markers of lipid damage. This was accompanied by evidence of increased mitochondrial fission. We also observed increased expression of cellular stress markers, HSP70 and HSP60, following exposure to THC. These effects were coincident with reduced mitochondrial respiratory function and a decrease in mitochondrial membrane potential. Taken together, our results suggest that THC can induce mitochondrial dysfunction and reduce trophoblast invasion; outcomes that have been previously linked to poor placentation. We also demonstrate that these changes in HTR8/SVneo biology may be variably mediated by cannabinoid receptors CB1 and CB2.

Inhibition of EGR-1-dependent MMP1 transcription by ethanol extract of Ageratum houstonianum in HaCaT keratinocytes

Matrix metalloproteinase 1 (MMP-1) initiates the breakdown of matrix networks by cleaving fibrillar collagen during the pathophysiological progression of skin aging. Ageratum houstonianum ethanol extract (AHE) has been used as a traditional herbal medicine to treat external wounds and skin diseases. However, the mechanism of action underlying A. houstonianum-mediated modulation of skin aging has not been investigated. In this study, we evaluated the effect of AHE on MMP-1 expression in HaCaT keratinocytes. Gene expression was analyzed by Reverse transcription-PCR (RT-PCR), Quantitative real-time PCR (Q-PCR), gene promoter-reporter assay, and immunoblotting. We found that AHE abrogated TNFα-induced MMP1 expression at the transcriptional level via the suppression of ERK1/2 mitogen-activated protein kinase (MAPK)-mediated Early Growth Response 1 (EGR1) expression. We also demonstrated that β-caryophyllene, a cannabinoid receptor 2 (CB2) agonist, is a functional component of the AHE that inhibits TNFα-induced EGR-1 and MMP1 expression. AHE exerts inhibitory activity on TNFα-induced MMP1 expression at the transcription level through EGR-1 downregulation in keratinocytes. β-Caryophyllene is a bioactive ingredient of AHE that is responsible for the inhibition of TNFα-induced EGR1 expression. β-Caryophyllene can be used as a potential agent to prevent inflammation-induced skin aging.

Cannabis, the Endocannabinoid System and Immunity-the Journey from the Bedside to the Bench and Back

The Cannabis plant contains numerous components, including cannabinoids and other active molecules. The phyto-cannabinoid activity is mediated by the endocannabinoid system. Cannabinoids affect the nervous system and play significant roles in the regulation of the immune system. While Cannabis is not yet registered as a drug, the potential of cannabinoid-based medicines for the treatment of various conditions has led many countries to authorize their clinical use. However, the data from basic and medical research dedicated to medical Cannabis is currently limited. A variety of pathological conditions involve dysregulation of the immune system. For example, in cancer, immune surveillance and cancer immuno-editing result in immune tolerance. On the other hand, in autoimmune diseases increased immune activity causes tissue damage. Immuno-modulating therapies can regulate the immune system and therefore the immune-regulatory properties of cannabinoids, suggest their use in the therapy of immune related disorders. In this contemporary review, we discuss the roles of the endocannabinoid system in immunity and explore the emerging data about the effects of cannabinoids on the immune response in different pathologies. In addition, we discuss the complexities of using cannabinoid-based treatments in each of these conditions.

Cannabinoid Receptor 2 Modulates Maturation of Dendritic Cells and Their Capacity to Induce Hapten-Induced Contact Hypersensitivity

Contact hypersensitivity (CHS) is an established animal model for allergic contact dermatitis. Dendritic cells (DCs) play an important role in the sensitization phase of CHS by initiating T cell responses to topically applied haptens. The cannabinoid receptors 1 (CB1) and 2 (CB2) modulate DC functions and inflammatory skin responses, but their influence on the capacity of haptenized DCs to induce CHS is still unknown. We found lower CHS responses to 2,4-dinitro-1-fluorobenzene (DNFB) in wild type (WT) mice after adoptive transfer of haptenized Cnr2^-/- and Cnr1^-/-/Cnr2^-/- bone marrow (BM) DCs as compared to transfer of WT DCs. In contrast, induction of CHS was not affected in WT recipients after transfer of Cnr1^-/- DCs. In vitro stimulated Cnr2^-/- DCs showed lower CCR7 and CXCR4 expression when compared to WT cells, while in vitro migration towards the chemokine ligands was not affected by CB2. Upregulation of MHC class II and co-stimulatory molecules was also reduced in Cnr2^-/- DCs. This study demonstrates that CB2 modulates the maturation phenotype of DCs but not their chemotactic capacities in vitro. These findings and the fact that CHS responses mediated by Cnr2^-/- DCs are reduced suggest that CB2 is a promising target for the treatment of inflammatory skin conditions.

A Novel Gastric Spheroid Co-culture Model Reveals Chemokine-Dependent Recruitment of Human Dendritic Cells to the Gastric Epithelium

BACKGROUND & AIMS

Gastric dendritic cells (DCs) control the adaptive response to infection with Helicobacter pylori, a major risk factor for peptic ulcer disease and gastric cancer. We hypothesize that DC interactions with the gastric epithelium position gastric DCs for uptake of luminal H pylori and promote DC responses to epithelial-derived mediators. The aim of this study was to determine whether the gastric epithelium actively recruits DCs using a novel co-culture model of human gastric epithelial spheroids and monocyte-derived DCs.

METHODS

Spheroid cultures of primary gastric epithelial cells were infected with H pylori by microinjection. Co-cultures were established by adding human monocyte-derived DCs to the spheroid cultures and were analyzed for DC recruitment and antigen uptake by confocal microscopy. Protein array, gene expression polymerase chain reaction array, and chemotaxis assays were used to identify epithelial-derived chemotactic factors that attract DCs. Data from the co-culture model were confirmed using human gastric tissue samples.

RESULTS

Human monocyte-derived DCs co-cultured with gastric spheroids spontaneously migrated to the gastric epithelium, established tight interactions with the epithelial cells, and phagocytosed luminally applied H pylori. DC recruitment was increased upon H pylori infection of the spheroids and involved the activity of multiple chemokines including CXCL1, CXCL16, CXCL17, and CCL20. Enhanced chemokine expression and DC recruitment to the gastric epithelium also was observed in H pylori-infected human gastric tissue samples.

CONCLUSIONS

Our results indicate that the gastric epithelium actively recruits DCs for immunosurveillance and pathogen sampling through chemokine-dependent mechanisms, with increased recruitment upon active H pylori infection.

Cannabinoid receptor 2 deficiency exacerbates inflammation and neutrophil recruitment

Cannabinoid receptor (CB)₂ is an immune cell–localized GPCR that has been hypothesized to regulate the magnitude of inflammatory responses. However, there is currently no consensus as to the mechanism by which CB₂ mediates its anti-inflammatory effects in vivo. To address this question, we employed a murine dorsal air pouch model with wild-type and CB₂^−/− 8–12-wk-old female and male C57BL/6 mice and found that acute neutrophil and lymphocyte antigen 6 complex, locus C^hi monocyte recruitment in response to Zymosan was significantly enhanced in CB₂^−/− mice. Additionally, levels of matrix metalloproteinase 9 and the chemokines C-C motif chemokine ligand (CCL)2, CCL4, and C-X-C motif chemokine ligand 10 in CB₂^−/− pouch exudates were elevated at earlier time points. Importantly, using mixed bone marrow chimeras, we revealed that the proinflammatory phenotype in CB₂^−/− mice is neutrophil-intrinsic rather than stromal cell–dependent. Indeed, neutrophils isolated from CB₂^−/− mice exhibited an enhanced migration-related transcriptional profile and increased adhesive phenotype, and treatment of human neutrophils with a CB₂ agonist blocked their endothelial transmigration. Overall, we have demonstrated that CB₂ plays a nonredundant role during acute neutrophil mobilization to sites of inflammation and, as such, it could represent a therapeutic target for the development of novel anti-inflammatory compounds to treat inflammatory human diseases.—Kapellos, T. S., Taylor, L., Feuerborn, A., Valaris, S., Hussain, M. T., Rainger, G. E., Greaves, D. R., Iqbal, A. J. Cannabinoid receptor 2 deficiency exacerbates inflammation and neutrophil recruitment.

∆9-tetrahydrocannabinol inhibits epithelial-mesenchymal transition and metastasis by targeting matrix metalloproteinase-9 in endometrial cancer

Limited therapeutic interventions are clinically available for treating aggressive endometrial cancer (EC). Therefore, effective therapies are urgently required. Therefore, the present study investigated the role of ∆⁹-tetrahydrocannabinol (THC), which is reported to impact proliferative and migratory activities during impairment of cancer progression. In the present study, cell migration in response to THC was measured using transwell assays. Using western blot analysis, the levels of cannabinoid receptors in EC tissues were detected and pathways leading to the inhibition of cell migration by THC on human EC cells were determined. Results suggested that cannabinoid receptors were highly expressed in EC tissues. Furthermore, THC inhibited EC cell viability and motility by inhibiting epithelial-mesenchymal transition (EMT) and downregulating matrix metalloproteinase-9 (MMP-9) gene expression in aggressive human EC cells. The results have the potential to promote the development of novel compounds for the treatment of EC metastasis. The presnet findings suggest that THC may inhibit human EC cell migration through regulating EMT and MMP-9 pathways.

Surprising outcomes in cannabinoid CB1/CB2 receptor double knockout mice in two models of ischemia

AIMS

We tested the hypothesis that CB1/CB2 receptor double knockout would produce significant increases in infarct size and volume and significant worsening in clinical score, using two mouse models, one of permanent ischemia and one of ischemia/reperfusion.

MAIN METHODS

Focal cerebral infarcts were created using either photo induced permanent injury or transient middle cerebral artery occlusion. Infarct volume and motor function were evaluated in cannabinoid receptor 1/cannabinoid receptor 2 double knockout mice.

KEY FINDINGS

The results surprisingly revealed that CB1/CB2 double knockout mice showed improved outcomes, with the most improvements in the mouse model of permanent ischemia.

SIGNIFICANCE

Although the number of individuals suffering from stroke in the United States and worldwide will continue to grow, therapeutic intervention for treatment following stroke remains frustratingly limited. Both the cannabinoid 1 receptor (CB1R) and the cannabinoid 2 receptor (CB2R) have been studied in relationship to stroke. Deletion of the CB2R has been shown to worsen outcome, while selective CB2R agonists have been demonstrated to be neuroprotective following stroke. Although initial studies of CB1R knockout mice demonstrated increased injury following stroke, indicating that activation of the CB1R was neuroprotective, later studies of selective antagonists of the CB1R also demonstrated a protective effect. Surprisingly the double knockout animals had improved outcome. Since the phenotype of the double knockout is not dramatically changed, significant changes in the contribution of other homeostatic pathways in compensation for the loss of these two important receptors may explain these apparently contradictory results.

Cannabinoid Receptor 2 Modulates Neutrophil Recruitment in a Murine Model of Endotoxemia

The endocannabinoid system consists of endogenous lipid mediators and cannabinoid receptors (CB) 1 and 2. It has previously been demonstrated that activation of the leukocyte-expressed CB₂ has anti-inflammatory effects in vivo. Here, we report its role under baseline conditions and in a model of low-dose endotoxemia by comparing CB₂ knockout to littermate control mice. CB₂-deficient mice displayed significantly more neutrophils and fewer monocytes in the bone marrow under steady state. In initial validation experiments, administration of 1 mg/kg LPS to male C57BL/6J mice was shown to transiently upregulate systemic proinflammatory mediators (peaked at 2 hours) and mobilise bone marrow neutrophils and monocytes into circulation. In CB₂ knockout mice, the level of the metalloproteinase MMP-9 was significantly elevated by 2 hours and we also observed augmented recruitment of neutrophils to the spleen in addition to increased levels of Ccl2, Ccl3, Cxcl10, and Il6. Collectively, our data show that the absence of CB₂ receptor increases the levels of innate immune cell populations in the bone marrow under steady state. Furthermore, during an acute systemic inflammatory insult, we observe a highly reproducible and site-specific increase in neutrophil recruitment and proinflammatory chemokine expression in the spleen of CB₂ knockout mice.

Thymidine phosphorylase promotes metastasis and serves as a marker of poor prognosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) ranks as one of the most common and lethal malignancies worldwide. A better understanding of the mechanism responsible for HCC metastasis will be helpful for the treatment of HCC patients. Thymidine phosphorylase (TP), a key enzyme that catalyzes the conversion of thymidine to thymine and deoxyribose-1-phosphate, was demonstrated to promote the invasion and metastasis of HCC in our study. Clinical retrospective analysis revealed that metastatic HCC tumor tissues have higher TP expression, and TP expression was significantly correlated with matrix metalloproteinase (MMP) 2 and 9 expression. Survival analysis revealed that TP expression was negatively correlated with the prognosis of HCC patients. Moreover, in vitro cell experiments confirmed that TP could promote the migration and invasion of HCC cells. In addition, MMP2 and MMP9 were activated by TP overexpression. Overall, this study suggests that TP promotes metastasis and may serve as a marker of poor prognosis in HCC. Thus, TP is a potential target for the treatment of HCC.

Seeing over the horizon - targeting the endocannabinoid system for the treatment of ocular disease

The observation that marijuana reduces intraocular pressure was made by Hepler and Frank in the 1970s. Since then, there has been a significant body of work investigating cannabinoids for their potential use as therapeutics. To date, no endocannabinoid system (ECS)-modulating drug has been approved for clinical use in the eye; however, recent advances in our understanding of the ECS, as well as new pharmacological tools, has renewed interest in the development of ocular ECS-based therapeutics. This review summarizes the current state-of-affairs for the use of ECS-modulating drugs for the treatment of glaucoma and ocular inflammatory and ischemic disease.

Cannabinoid CB1 and CB2 Receptor Signaling and Bias

An agonist that acts through a single receptor can activate numerous signaling pathways. Recent studies have suggested that different ligands can differentially activate these pathways by stabilizing a limited range of receptor conformations, which in turn preferentially drive different downstream signaling cascades. This concept, termed "biased signaling" represents an exciting therapeutic opportunity to target specific pathways that elicit only desired effects, while avoiding undesired effects mediated by different signaling cascades. The cannabinoid receptors CB1 and CB2 each activate multiple pathways, and evidence is emerging for bias within these pathways. This review will summarize the current evidence for biased signaling through cannabinoid receptor subtypes CB1 and CB2.

The CB2 receptor and its role as a regulator of inflammation

The CB2 receptor is the peripheral receptor for cannabinoids. It is mainly expressed in immune tissues, highlighting the possibility that the endocannabinoid system has an immunomodulatory role. In this respect, the CB2 receptor was shown to modulate immune cell functions, both in cellulo and in animal models of inflammatory diseases. In this regard, numerous studies have reported that mice lacking the CB2 receptor have an exacerbated inflammatory phenotype. This suggests that therapeutic strategies aiming at modulating CB2 signaling could be promising for the treatment of various inflammatory conditions. Herein, we review the pharmacology of the CB2 receptor, its expression pattern, and the signaling pathways induced by its activation. We next examine the regulation of immune cell functions by the CB2 receptor and the evidence obtained from primary human cells, immortalized cell lines, and animal models of inflammation. Finally, we discuss the possible therapies targeting the CB2 receptor and the questions that remain to be addressed to determine whether this receptor could be a potential target to treat inflammatory disease.

Impact of Cannabis, Cannabinoids, and Endocannabinoids in the Lungs

Since the identification of cannabinoid receptors in the 1990s, a research field has been dedicated to exploring the role of the cannabinoid system in immunity and the inflammatory response in human tissues and animal models. Although the cannabinoid system is present and crucial in many human tissues, studying the impact of cannabinoids on the lungs is particularly relevant because of their contact with exogenous cannabinoids in the context of marijuana consumption. In the past two decades, the scientific community has gathered a large body of evidence supporting that the activation of the cannabinoid system alleviates pain and reduces inflammation. In the context of lung inflammation, exogenous and endogenous cannabinoids have shown therapeutic potential because of their inhibitory effects on immune cell recruitment and functions. On the other hand, cannabinoids were shown to be deleterious to lung function and to impact respiratory pathogen clearance. In this review, we present the existing data on the regulation of lung immunity and inflammation by phytocannabinoids, synthetic cannabinoids and endocannabinoids.

Cannabinoid Receptor 1 Mediates Homing of Bone Marrow-Derived Mesenchymal Stem Cells Triggered by Chronic Liver Injury

Cannabinoid receptors (CBs) have been implicated in the pathogenesis of various liver diseases, including liver fibrosis. Our previous studies have demonstrated that after liver injury, mouse bone marrow-derived mesenchymal stem cells (BMSCs) can migrate to the injured liver and differentiate to myofibroblasts, contributing to hepatic fibrogenesis. However, the role of CBs in the homing of BMSCs in liver injury is yet unclear. In this study, we found that both CB1 and CB2 were expressed in BMSCs. Migration assays were performed by transwell chambers. CB1 agonist ACEA promoted the migration of BMSCs, but CB2 agonist JWH133 had no effect. Pharmacological or genetic ablation of CB1 reduced ACEA-induced migration, whereas CB2 did not. Moreover, activation of CB1 increased active GTP-bound Rac1, RhoA, and Cdc42 protein levels. The elevated GTP-bound Rac1 and RhoA protein levels were decreased by CB1 antagonist AM281 treatment, but not Cdc42. In addition, ACEA-induced migration was suppressed by NSC23766 (Rac1 inhibitor) or C3 transferase (RhoA inhibitor), whereas MLS-573151 (Cdc42 inhibitor) had no effect. Consistent with these data, Rac1 or RhoA knock-down significantly blocked CB1-mediated migration. Meanwhile, CB1-mediated migration was associated with cytoskeletal remodeling. In vivo, administration of CB1 antagonist AM281 markedly inhibited the recruitment of BMSCs to the injured liver using fluorescence-activated cell sorting. Furthermore, blockade of CB1 significantly attenuated liver fibrosis. In conclusion, our results suggest that CB1 plays a crucial role in liver fibrosis through mediating the homing of BMSCs to damaged liver, which may provide new insight into the pathogenesis and treatment of liver fibrosis. J. Cell. Physiol. 232: 110-121, 2017. © 2016 Wiley Periodicals, Inc.

Pharmacological benefits of selective modulation of cannabinoid receptor type 2 (CB2) in experimental Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that pervasively affects the population across the world. Currently, there is no effective treatment available for this and existing drugs merely slow the progression of cognitive function decline. Thus, massive effort is required to find an intended therapeutic target to overcome this condition. The present study has been framed to investigate the ameliorative role of selective modulator of cannabinoid receptor type 2 (CB2), 1-phenylisatin in experimental AD condition. We have induced experimental AD in mice by using two induction models viz., intracerebroventricular (i.c.v.) administration of streptozotocin (STZ) and aluminum trichloride (AlCl3)+d-galactose. Morris water maze (MWM) and attentional set shifting test (ASST) were used to assess learning and memory. Hematoxylin-eosin and Congo red staining were used to examine the structural variation in brain. Brain oxidative stress (thiobarbituric acid reactive substance and glutathione), nitric oxide levels (nitrites/nitrates), acetyl cholinesterase activity, myeloperoxidase and calcium levels were also estimated. i.c.v. STZ as well as AlCl3+d-galactose have impaired spatial and reversal learning with executive functioning, increased brain oxidative and nitrosative stress, cholinergic activity, inflammation and calcium levels. Furthermore, these agents have also enhanced the burden of Aβ plaque in the brain. Treatment with 1-phenylisatin and donepezil attenuated i.c.v. STZ as well as AlCl3+d-galactose induced impairment of learning-memory, brain biochemistry and brain damage. Hence, this study concludes that CB2 receptor modulation can be a potential therapeutic target for the management of AD.

A Cannabinoid Receptor 2 Agonist Prevents Thrombin-Induced Blood-Brain Barrier Damage via the Inhibition of Microglial Activation and Matrix Metalloproteinase Expression in Rats

Thrombin mediates the life-threatening cerebral edema and blood-brain barrier (BBB) damage that occurs after intracerebral hemorrhage (ICH). We previously found that the selective cannabinoid receptor 2 (CB2R) agonist JWH-133 reduced brain edema and neurological deficits following germinal matrix hemorrhage (GMH). We explored whether CB2R stimulation ameliorated thrombin-induced brain edema and BBB permeability as well as the possible molecular mechanism involved. A total of 144 Sprague-Dawley (S-D) rats received a thrombin (20 U) injection in the right basal ganglia. JWH-133 (1.5 mg/kg) or SR-144528 (3.0 mg/kg) and vehicle were intraperitoneally (i.p.) injected 1 h after surgery. Brain water content measurement, Evans blue (EB) extravasation, Western blot, and immunofluorescence were used to study the effects of a CB2R agonist 24 h after surgery. The results demonstrated that JWH-133 administration significantly decreased thrombin-induced brain edema and reduced the number of Iba-1-positive microglia. JWH-133 also decreased the number of P44/P42(+)/Iba-1(+) microglia, lowered Evans blue extravasation, and inhibited the elevated matrix metallopeptidase (MMP)-9 and matrix metallopeptidase (MMP)-12 activities. However, a selective CB2R antagonist (SR-144528) reversed these effects. We demonstrated that CB2R stimulation reduced thrombin-induced brain edema and alleviated BBB damage. We also found that matrix metalloproteinase suppression may be partially involved in these processes.

Activating cannabinoid receptor 2 alleviates pathogenesis of experimental autoimmune encephalomyelitis via activation of autophagy and inhibiting NLRP3 inflammasome

AIMS

Activation of cannabinoid receptor 2 (CB2R) has been reported to ameliorate the pathogenesis of experimental autoimmune encephalomyelitis (EAE). In this study, we examined whether autophagy is involved in the beneficial effect of CB2R on EAE and explored the mechanism with a focus on inflammasome activation.

METHODS

EAE severity was analyzed with clinical score and histological score stained by hematoxylin and eosin or luxol fast blue in spinal cord. Immunoblot analysis was conducted to detect proteins of NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome-related caspase-1 (Casp-1) and the maturation of interleukin (IL)-1β as well as autophagy-related light chain 3 (LC3), and Beciln 1 both in vivo and in vitro. Reverse transcription and real-time PCR were used to detect mRNA of NLRP3, IL-1β and Casp-1. Autophagy-related gene 5 (ATG5)-specific siRNA was transiently transfected in BV2 microglia, and immunofluorescence staining was carried out to detect the expression of NLRP3, caspase recruitment domain (ASC), and pro-caspase-1.

RESULTS

The current data indicated that deleting CB2R decreased the expression of LC3-II/LC3-I ratio, Beclin 1 and increased caspase-1 activation and IL-1β production in the spinal cord of EAE mice, whereas activation of CB2R with a specific agonist HU-308 induced inverse effects. Further study indicated that HU-308 could promote autophagy and inhibit expression and activation of NLRP3 inflammasome in BV2 microglia. Blocking autophagy by ATG5-specific siRNA dismissed the effort of CB2R in mediating NLRP3 inflammasome in vitro.

CONCLUSION

Collectively, our results demonstrated for the first time that CB2R plays a protective role in EAE through promoting autophagy and inhibiting NLRP3 inflammasome activation.

Cannabidiol for the Prevention of Graft-versus-Host-Disease after Allogeneic Hematopoietic Cell Transplantation: Results of a Phase II Study

Graft-versus-host-disease (GVHD) is a major obstacle to successful allogeneic hematopoietic cell transplantation (alloHCT). Cannabidiol (CBD), a nonpsychotropic ingredient of Cannabis sativa, possesses potent anti-inflammatory and immunosuppressive properties. We hypothesized that CBD may decrease GVHD incidence and severity after alloHCT. We conducted a phase II study. GVHD prophylaxis consisted of cyclosporine and a short course of methotrexate. Patients transplanted from an unrelated donor were given low-dose anti-T cell globulin. CBD 300 mg/day was given orally starting 7 days before transplantation until day 30. Forty-eight consecutive adult patients undergoing alloHCT were enrolled. Thirty-eight patients (79%) had acute leukemia or myelodysplastic syndrome and 35 patients (73%) were given myeloablative conditioning. The donor was either an HLA-identical sibling (n = 28), a 10/10 matched unrelated donor (n = 16), or a 1-antigen-mismatched unrelated donor (n = 4). The median follow-up was 16 months (range, 7 to 23). No grades 3 to 4 toxicities were attributed to CBD. None of the patients developed acute GVHD while consuming CBD. In an intention-to-treat analysis, we found that the cumulative incidence rates of grades II to IV and grades III to IV acute GVHD by day 100 were 12.1% and 5%, respectively. Compared with 101 historical control subjects given standard GVHD prophylaxis, the hazard ratio of developing grades II to IV acute GVHD among subjects treated with CBD plus standard GVHD prophylaxis was .3 (P = .0002). Rates of nonrelapse mortality at 100 days and at 1 year after transplantation were 8.6% and 13.4%, respectively. Among patients surviving more than 100 days, the cumulative incidences of moderate-to-severe chronic GVHD at 12 and 18 months were 20% and 33%, respectively. The combination of CBD with standard GVHD prophylaxis is a safe and promising strategy to reduce the incidence of acute GVHD. A randomized double-blind controlled study is warranted. (clinicaltrials.gov: NCT01385124).

Cannabinoid Receptor-2 Regulates Embryonic Hematopoietic Stem Cell Development via Prostaglandin E2 and P-Selectin Activity

Cannabinoids (CB) modulate adult hematopoietic stem and progenitor cell (HSPCs) function, however, impact on the production, expansion, or migration of embryonic HSCs is currently uncharacterized. Here, using chemical and genetic approaches targeting CB-signaling in zebrafish, we show that CB receptor (CNR) 2, but not CNR1, regulates embryonic HSC development. During HSC specification in the aorta-gonad-mesonephros (AGM) region, CNR2 stimulation by AM1241 increased runx1;cmyb(+) HSPCs, through heightened proliferation, whereas CNR2 antagonism decreased HSPC number; FACS analysis and absolute HSC counts confirmed and quantified these effects. Epistatic investigations showed AM1241 significantly upregulated PGE2 synthesis in a Ptgs2-dependent manner to increase AGM HSCs. During the phases of HSC production and colonization of secondary niches, AM1241 accelerated migration to the caudal hematopoietic tissue (CHT), the site of embryonic HSC expansion, and the thymus; however these effects occurred independently of PGE2. Using a candidate approach for HSC migration and retention factors, P-selectin was identified as the functional target of CNR2 regulation. Epistatic analyses confirmed migration of HSCs into the CHT and thymus was dependent on CNR2-regulated P-selectin activity. Together, these data suggest CNR2-signaling optimizes the production, expansion, and migration of embryonic HSCs by modulating multiple downstream signaling pathways.

Protective role of cannabinoid receptor 2 activation in galactosamine/lipopolysaccharide-induced acute liver failure through regulation of macrophage polarization and microRNAs

Acute liver failure (ALF) is a potentially life-threatening disorder without any effective treatment strategies. d-Galactosamine (GalN)/lipopolysaccharide (LPS)-induced ALF is a widely used animal model to identify novel hepato-protective agents. In the present study, we investigated the potential of a cannabinoid receptor 2 (CB2) agonist, JWH-133 [(6aR,10aR)-3-(1,1-dimethylbutyl)-6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran], in the amelioration of GalN/LPS-induced ALF. JWH-133 treatment protected the mice from ALF-associated mortality, mitigated alanine transaminase and proinflammatory cytokines, suppressed histopathological and apoptotic liver damage, and reduced liver infiltration of mononuclear cells (MNCs). Furthermore, JWH-133 pretreatment of M1/M2-polarized macrophages significantly increased the secretion of anti-inflammatory cytokine interleukin-10 (IL-10) in M1 macrophages and potentiated the expression of M2 markers in M2-polarized macrophages. In vivo, JWH-133 treatment also suppressed ALF-triggered expression of M1 markers in liver MNCs, while increasing the expression of M2 markers such as Arg1 and IL-10. microRNA (miR) microarray analysis revealed that JWH-133 treatment altered the expression of only a few miRs in the liver MNCs. Gene ontology analysis of the targets of miRs suggested that Toll-like receptor (TLR) signaling was among the most significantly targeted cellular pathways. Among the altered miRs, miR-145 was found to be the most significantly decreased. This finding correlated with concurrent upregulated expression of its predicted target gene, interleukin-1 receptor-associated kinase 3, a negative regulator of TLR4 signaling. Together, these data are the first to demonstrate that CB2 activation attenuates GalN/LPS-induced ALF by inducing an M1 to M2 shift in macrophages and by regulating the expression of unique miRs that target key molecules involved in the TLR4 pathway.

Genetic Manipulation of the Endocannabinoid System

The physiological and pathophysiological functions of the endocannabinoid system have been studied extensively using transgenic and targeted knockout mouse models. The first gene deletions of the cannabinoid CB(1) receptor were described in the late 1990s, soon followed by CB(2) and FAAH mutations in early 2000. These mouse models helped to elucidate the fundamental role of endocannabinoids as retrograde transmitters in the CNS and in the discovery of many unexpected endocannabinoid functions, for example, in the skin, bone and liver. We now have knockout mouse models for almost every receptor and enzyme of the endocannabinoid system. Conditional mutant mice were mostly developed for the CB(1) receptor, which is widely expressed on many different neurons, astrocytes and microglia, as well as on many cells outside the CNS. These mouse strains include "floxed" CB(1) alleles and mice with a conditional re-expression of CB(1). The availability of these mice made it possible to decipher the function of CB(1) in specific neuronal circuits and cell populations or to discriminate between central and peripheral effects. Many of the genetic mouse models were also used in combination with viral expression systems. The purpose of this review is to provide a comprehensive overview of the existing genetic models and to summarize some of the most important discoveries that were made with these animals.

The endocannabinoid system modulates stress, emotionality, and inflammation

The physiological and behavioral effects of stress are well characterized. Endocannabinoids are produced on demand and function to attenuate many of the physiological effects of the stress response. The endocannabinoid system is made up of cannabinoid receptors, the fatty acid signaling molecules that bind to and activate these receptors, and the enzymes that synthesize and catabolize these endocannabinoid signaling molecules. Cannabinoid research has recently grown substantially, due in no small part to the development of genetic research models as well as highly selective pharmaceutical tools. The purpose of this minireview is to discuss a subset of the many parallels between cannabinoid and behavioral neuroimmunology research, with specific discussion of interactions between the endocannabinoid system and psychological stress, emotionality, and inflammation.

Pristimerin, a naturally occurring triterpenoid, protects against autoimmune arthritis by modulating the cellular and soluble immune mediators of inflammation and tissue damage

Rheumatoid arthritis (RA) is a chronic autoimmune disorder affecting the synovial joints. The currently available drugs for RA are effective only in a proportion of patients and their prolonged use is associated with severe adverse effects. Thus, new anti-arthritic agents are being sought. We tested Pristimerin, a naturally occurring triterpenoid, for its therapeutic activity against rat adjuvant arthritis. Pristimerin effectively inhibited both arthritic inflammation and cartilage and bone damage in the joints. Pristimerin-treated rats exhibited a reduction in the pro-inflammatory cytokines (IL-6, IL-17, IL-18, and IL-23) and the IL-6/IL-17-associated transcription factors (pSTAT3 and ROR-γt), coupled with an increase in the immunomodulatory cytokine IL-10. Also increased was IFN-γ, which can inhibit IL-17 response. In addition, the Th17/Treg ratio was altered in favor of immune suppression and the RANKL/OPG ratio was skewed towards anti-osteoclastogenesis. This is the first report on testing Pristimerin in arthritis. We suggest further evaluation of Pristimerin in RA patients.