The Cannabinoid Receptor 2 Protects Against Alcoholic Liver Disease Via a Macrophage Autophagy-Dependent Pathway

Cannabinoids and triple-negative breast cancer treatment

Triple-negative breast cancer (TNBC) accounts for about 10-20% of all breast cancer cases and is associated with an unfavorable prognosis. Until recently, treatment options for TNBC were limited to chemotherapy. A new successful systemic treatment is immunotherapy with immune checkpoint inhibitors, but new tumor-specific biomarkers are needed to improve patient outcomes. Cannabinoids show antitumor activity in most preclinical studies in TNBC models and do not appear to have adverse effects on chemotherapy. Clinical data are needed to evaluate efficacy and safety in humans. Importantly, the endocannabinoid system is linked to the immune system and immunosuppression. Therefore, cannabinoid receptors could be a potential biomarker for immune checkpoint inhibitor therapy or a novel mechanism to reverse resistance to immunotherapy. In this article, we provide an overview of the currently available information on how cannabinoids may influence standard therapy in TNBC.

The Impact of the CB2 Cannabinoid Receptor in Inflammatory Diseases: An Update

The emergence of inflammatory diseases is a heavy burden on modern societies. Cannabis has been used for several millennia to treat inflammatory disorders such as rheumatism or gout. Since the characterization of cannabinoid receptors, CB1 and CB2, the potential of cannabinoid pharmacotherapy in inflammatory conditions has received great interest. Several studies have identified the importance of these receptors in immune cell migration and in the production of inflammatory mediators. As the presence of the CB2 receptor was documented to be more predominant in immune cells, several pharmacological agonists and antagonists have been designed to treat inflammation. To better define the potential of the CB2 receptor, three online databases, PubMed, Google Scholar and clinicaltrial.gov, were searched without language restriction. The full texts of articles presenting data on the endocannabinoid system, the CB2 receptor and its role in modulating inflammation in vitro, in animal models and in the context of clinical trials were reviewed. Finally, we discuss the clinical potential of the latest cannabinoid-based therapies in inflammatory diseases.

Macrophage Perspectives in Liver Diseases: Programmed Death, Related Biomarkers, and Targeted Therapy

Macrophages, as important immune cells of the organism, are involved in maintaining intrahepatic microenvironmental homeostasis and can undergo rapid phenotypic changes in the injured or recovering liver. In recent years, the crucial role of macrophage-programmed cell death in the development and regression of liver diseases has become a research hotspot. Moreover, macrophage-targeted therapeutic strategies are emerging in both preclinical and clinical studies. Given the macrophages' vital role in complex organismal environments, there is tremendous academic interest in developing novel therapeutic strategies that target these cells. This review provides an overview of the characteristics and interactions between macrophage polarization, programmed cell death, related biomarkers, and macrophage-targeted therapies. It aims to deepen the understanding of macrophage immunomodulation and molecular mechanisms and to provide a basis for the treatment of macrophage-associated liver diseases.

MicroRNA-7 deficiency ameliorates d-galactose-induced aging in mice by regulating senescence of Kupffer cells

Aging is intricately linked to immune system dysfunction. Recent studies have highlighted the biological function of microRNA-7 (miR-7) as a novel regulator of immune cell function and related diseases. However, the potential role of miR-7 in aging remains unexplored. Here, we investigated the contribution of miR-7 to d-gal-induced aging in mice, focusing on its regulation of senescent Kupffer cells. Our findings revealed that miR-7 deficiency significantly ameliorated the aging process, characterized by enhanced CD4+ T-cell activation. However, the adoptive transfer of miR-7-deficient CD4+T cells failed to improve the age-related phenotype. Further analysis showed that miR-7 deficiency significantly reduced IL-1β production in liver tissue, and inhibiting IL-1β in vivo slowed down the aging process in mice. Notably, IL-1β is mainly produced by senescent Kupffer cells in the liver tissue of aging mice, and miR-7 expression was significantly up-regulated in these cells. Mechanistically, KLF4, a target of miR-7, was down-regulated in senescent Kupffer cells in aging mouse model. Furthermore, miR-7 deficiency also modulated the NF-κB activation and IL-1β production in senescent Kupffer cells through KLF4. In conclusion, our findings unveil the role of miR-7 in d-gal-induced aging in mice, highlighting its regulation of KLF4/NF-κB/IL-1β pathways in senescent Kupffer cells. This research may enhance our understanding of miRNA-based aging immune cells and offer new avenues for new intervention strategies in aging process.

The Role of Cannabidiol in Liver Disease: A Systemic Review

Cannabidiol (CBD), a non-psychoactive phytocannabinoid abundant in Cannabis sativa, has gained considerable attention for its anti-inflammatory, antioxidant, analgesic, and neuroprotective properties. It exhibits the potential to prevent or slow the progression of various diseases, ranging from malignant tumors and viral infections to neurodegenerative disorders and ischemic diseases. Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease, and viral hepatitis stand as prominent causes of morbidity and mortality in chronic liver diseases globally. The literature has substantiated CBD's potential therapeutic effects across diverse liver diseases in in vivo and in vitro models. However, the precise mechanism of action remains elusive, and an absence of evidence hinders its translation into clinical practice. This comprehensive review emphasizes the wealth of data linking CBD to liver diseases. Importantly, we delve into a detailed discussion of the receptors through which CBD might exert its effects, including cannabinoid receptors, CB1 and CB2, peroxisome proliferator-activated receptors (PPARs), G protein-coupled receptor 55 (GPR55), transient receptor potential channels (TRPs), and their intricate connections with liver diseases. In conclusion, we address new questions that warrant further investigation in this evolving field.

CB2 Cannabinoid Receptor as a Potential Target in Myocardial Infarction: Exploration of Molecular Pathogenesis and Therapeutic Strategies

The lipid endocannabinoid system has recently emerged as a novel therapeutic target for several inflammatory and tissue-damaging diseases, including those affecting the cardiovascular system. The primary targets of cannabinoids are cannabinoid type 1 (CB1) and 2 (CB2) receptors. The CB2 receptor is expressed in the cardiomyocytes. While the pathological changes in the myocardium upregulate the CB2 receptor, genetic deletion of the receptor aggravates the changes. The CB2 receptor plays a crucial role in attenuating the advancement of myocardial infarction (MI)-associated pathological changes in the myocardium. Activation of CB2 receptors exerts cardioprotection in MI via numerous molecular pathways. For instance, delta-9-tetrahydrocannabinol attenuated the progression of MI via modulation of the CB2 receptor-dependent anti-inflammatory mechanisms, including suppression of pro-inflammatory cytokines like IL-6, TNF-α, and IL-1β. Through similar mechanisms, natural and synthetic CB2 receptor ligands repair myocardial tissue damage. This review aims to offer an in-depth discussion on the ameliorative potential of CB2 receptors in myocardial injuries induced by a variety of pathogenic mechanisms. Further, the modulation of autophagy, TGF-β/Smad3 signaling, MPTP opening, and ROS production are discussed. The molecular correlation of CB2 receptors with cardiac injury markers, such as troponin I, LDH1, and CK-MB, is explored. Special attention has been paid to novel insights into the potential therapeutic implications of CB2 receptor activation in MI.

Research progress on the cannabinoid type-2 receptor and Parkinson's disease

Parkinson's disease (PD) is featured by movement impairments, including tremors, bradykinesia, muscle stiffness, and imbalance. PD is also associated with many non-motor symptoms, such as cognitive impairments, dementia, and mental disorders. Previous studies identify the associations between PD progression and factors such as α-synuclein aggregation, mitochondrial dysfunction, inflammation, and cell death. The cannabinoid type-2 receptor (CB2 receptor) is a transmembrane G-protein-coupled receptor and has been extensively studied as part of the endocannabinoid system. CB2 receptor is recently emerged as a promising target for anti-inflammatory treatment for neurodegenerative diseases. It is reported to modulate mitochondrial function, oxidative stress, iron transport, and neuroinflammation that contribute to neuronal cell death. Additionally, CB2 receptor possesses the potential to provide feedback on electrophysiological processes, offering new possibilities for PD treatment. This review summarized the mechanisms underlying PD pathogenesis. We also discussed the potential regulatory role played by CB2 receptor in PD.

Role of Cannabinoid Signaling in Cardiovascular Function and Ischemic Injury

Cardiovascular disease represents a leading cause of death, morbidity, and societal economic burden. The prevalence of cannabis use has significantly increased due to legalization and an increased societal acceptance of cannabis. Therefore, it is critically important that we gain a greater understanding of the effects and risks of cannabinoid use on cardiovascular diseases as well as the potential for cannabinoid-directed drugs to be used as therapeutics for the treatment of cardiovascular disease. This review summarizes our current understanding of the role of cannabinoid receptors in the pathophysiology of atherosclerosis and myocardial ischemia and explores their use as therapeutic targets in the treatment of ischemic heart disease. Endocannabinoids are elevated in patients with atherosclerosis, and activation of cannabinoid type 1 receptors (CB1Rs) generally leads to an enhancement of plaque formation and atherosclerosis. In contrast, selective activation of cannabinoid type 2 receptors (CB2Rs) appears to exert protective effects against atherosclerosis. Endocannabinoid signaling is also activated by myocardial ischemia. CB2R signaling appears to protect the heart from ischemic injury, whereas the role of CB1R in ischemic injury is less clear. This narrative review serves to summarize current research on the role of cannabinoid signaling in cardiovascular function with the goal of identifying critical knowledge gaps and future studies to address those gaps in a way that facilitates the development of new treatments and better cardiovascular health. SIGNIFICANCE STATEMENT: Cardiovascular diseases, including atherosclerosis and myocardial infarction, are a leading cause of death. Cannabinoid drugs have well known acute effects on cardiovascular function, including tachycardia and orthostatic hypotension. The recent legalization of marijuana and cannabinoids for both medical and recreational use has dramatically increased their prevalence of use. This narrative review on the role of cannabinoid signaling in cardiovascular disease contributes to a better understanding of this topic by integrating current knowledge and identifying critical gaps.

Ambiguous Pathogenic Roles of Macrophages in Alcohol-Associated Liver Diseases

Alcohol-associated liver disease (ALD) represents a major public health issue worldwide and is a leading etiology of liver cirrhosis. Alcohol-related liver injuries include a range of manifestations including alcoholic hepatitis (AH), simple steatosis, steatohepatitis, hepatic fibrosis, cirrhosis and liver cancer. Liver disease occurs from several pathological disturbances such as the metabolism of ethanol, which generates reactive oxygen species (ROS) in hepatocytes, alterations in the gut microbiota, and the immune response to these changes. A common hallmark of these liver affections is the establishment of an inflammatory environment, and some (broad) anti-inflammatory approaches are used to treat AH (eg, corticosteroids). Macrophages, which represent the main innate immune cells in the liver, respond to a wide variety of (pathogenic) stimuli and adopt a large spectrum of phenotypes. This translates to a diversity of functions including pathogen and debris clearance, recruitment of other immune cells, activation of fibroblasts, or tissue repair. Thus, macrophage populations play a crucial role in the course of ALD, but the underlying mechanisms driving macrophage polarization and their functionality in ALD are complex. In this review, we explore the various populations of hepatic macrophages in alcohol-associated liver disease and the underlying mechanisms driving their polarization. Additionally, we summarize the crosstalk between hepatic macrophages and other hepatic cell types in ALD, in order to support the exploration of targeted therapeutics by modulating macrophage polarization.

Autophagy, Oxidative Stress, and Alcoholic Liver Disease: A Systematic Review and Potential Clinical Applications

Ethanol consumption triggers oxidative stress by generating reactive oxygen species (ROS) through its metabolites. This process leads to steatosis and liver inflammation, which are critical for the development of alcoholic liver disease (ALD). Autophagy is a regulated dynamic process that sequesters damaged and excess cytoplasmic organelles for lysosomal degradation and may counteract the harmful effects of ROS-induced oxidative stress. These effects include hepatotoxicity, mitochondrial damage, steatosis, endoplasmic reticulum stress, inflammation, and iron overload. In liver diseases, particularly ALD, macroautophagy has been implicated as a protective mechanism in hepatocytes, although it does not appear to play the same role in stellate cells. Beyond the liver, autophagy may also mitigate the harmful effects of alcohol on other organs, thereby providing an additional layer of protection against ALD. This protective potential is further supported by studies showing that drugs that interact with autophagy, such as rapamycin, can prevent ALD development in animal models. This systematic review presents a comprehensive analysis of the literature, focusing on the role of autophagy in oxidative stress regulation, its involvement in organ-organ crosstalk relevant to ALD, and the potential of autophagy-targeting therapeutic strategies.

CB2R agonist GW405833 alleviates acute liver failure in mice via inhibiting HIF-1α-mediated reprogramming of glycometabolism and macrophage proliferation

The inflammatory responses involving infiltration and activation of liver macrophages play a vital role in acute liver failure (ALF). In the liver of ALF mice, cannabinoid receptor 2 (CB2R) is significantly upregulated on macrophages, while CB2R agonist GW405833 (GW) could protect against cell death in acute liver damage. In this study, we investigated the molecular mechanisms underlying the protective effects of GW against ALF in vivo and in vitro from a perspective of macrophage glycometabolism. Mice were pretreated with GW (10 mg/kg, i.p.), then were injected with D-GalN (750 mg/kg, i.p.) and LPS (10 mg/kg, i.p.) to induce ALF. We verified the protective effects of GW pretreatment in ALF mice. Furthermore, GW pretreatment significantly reduced liver macrophage infiltration and M1 polarization, and inhibited the release of inflammatory factors TNF-α and IL-1β in ALF mice. These protective effects were eliminated by CB2R antagonist SR144528 or in CB2R-/- ALF mice. We used LPS-stimulated RAW264.7 cells as an in vitro M1 macrophage-centered model of inflammatory response, and demonstrated that pretreatment with GW (10 μM) significantly reduced glucose metabolism by inhibiting glycolysis, which inhibited LPS-induced macrophage proliferation and inflammatory cytokines release. We verified these results in a stable CB2R-/- RAW264.7 cell line. Moreover, we found that GW significantly inhibited the expression of hypoxia inducible factor 1α (HIF-1α). Using a stable HIF-1α-/- RAW264.7 cell line, we confirmed that GW reduced the release of inflammatory cytokines from macrophages and inhibited glycolysis by downregulating HIF-1α expression. In conclusion, activation of CB2Rs inhibits the proliferation of hepatic macrophages and release of inflammatory factors in ALF mice through downregulating HIF-1α to inhibit glycolysis.

Autophagy in hepatic macrophages can be regulator and potential therapeutic target of liver diseases: A review

Hepatic macrophages are a complex population of cells that play an important role in the normal functioning of the liver and in liver diseases. Autophagy, as a maintainer of cellular homeostasis, is closely connected to many liver diseases. And its roles are not always beneficial, but manifesting as a double-edged sword. The polarization of macrophages and the activation of inflammasomes are mediated by intracellular and extracellular signals, respectively, and are important ways for macrophages to take part in a variety of liver diseases. More attention should be paid to autophagy of hepatic macrophages in liver diseases. In this review, we focus on the regulatory role of hepatic macrophages' autophagy in a variety of liver diseases; especially on the upstream regulator of polarization and inflammasomes activation of the hepatic macrophages. We believe that the autophagy of hepatic macrophages can become a potential therapeutic target for management of liver diseases.

Cannabinoid Type 2 Receptor Activation Reduces the Progression of Kidney Fibrosis Using a Mouse Model of Unilateral Ureteral Obstruction

Background: Kidney fibrosis is a hallmark consequence of all forms of chronic kidney disease with few available treatment modalities. Material and Methods: In this study, we performed the unilateral ureteral obstruction (UUO) procedure to investigate the effects of a selective cannabinoid type 2 (CB2) agonist receptor, SMM-295, as a nephroprotective therapy. Results: SMM-295 was demonstrated to exhibit 50-fold selectivity over the cannabinoid type 1 (CB1) receptor with an EC₅₀ ∼2 nM. Four other off-targets were identified in the safety panel, but only at the highest concentration (5 mM) tested in the assay demonstrating the relative selectivity and safety of our compound. Administration of SMM-295 (12 mg/kg IP daily) in UUO mice led to a significant decrease of 33% in tubular damage compared to the vehicle-treated UUO mice after 7 days. Consistent with these findings, there was a significant decrease in α-smooth muscle actin and fibronectin, which are markers of tubulointerstitial fibrosis, as determined by Western blot analysis. DNA damage as detected by a classic marker, γ-H2AX, was significantly reduced by 50% in the SMM-295 treatment group compared to vehicle treatment. Genetic knockout of CB2 or administration of a CB2 inverse agonist did not exhibit any beneficial effect on tubulointerstitial fibrosis or kidney tubule injury. Conclusions: In conclusion, our study provides new evidence that SMM-295 can therapeutically target the CB2 receptor with few, if any, physiological off-target sites to reduce kidney tissue damage and slow the fibrotic progression in a mouse model of kidney fibrosis.

Alcohol-Related Liver Disease: An Overview on Pathophysiology, Diagnosis and Therapeutic Perspectives

Alcohol-related liver disease (ALD) refers to a spectrum of liver manifestations ranging from fatty liver diseases, steatohepatitis, and fibrosis/cirrhosis with chronic inflammation primarily due to excessive alcohol use. Currently, ALD is considered as one of the most prevalent causes of liver disease-associated mortality worldwide. Although the pathogenesis of ALD has been intensively investigated, the present understanding of its biomarkers in the context of early clinical diagnosis is not complete, and novel therapeutic targets that can significantly alleviate advanced forms of ALD are limited. While alcohol abstinence remains the primary therapeutic intervention for managing ALD, there are currently no approved medications for treating ALD. Furthermore, given the similarities and the differences between ALD and non-alcoholic fatty liver disease in terms of disease progression and underlying molecular mechanisms, numerous studies have demonstrated that many therapeutic interventions targeting several signaling pathways, including oxidative stress, inflammatory response, hormonal regulation, and hepatocyte death play a significant role in ALD treatment. Therefore, in this review, we summarized several key molecular targets and their modes of action in ALD progression. We also described the updated therapeutic options for ALD management with a particular emphasis on potentially novel signaling pathways.

Interactions of Autophagy and the Immune System in Health and Diseases

Autophagy is a highly conserved process that utilizes lysosomes to selectively degrade a variety of intracellular cargo, thus providing quality control over cellular components and maintaining cellular regulatory functions. Autophagy is triggered by multiple stimuli ranging from nutrient starvation to microbial infection. Autophagy extensively shapes and modulates the inflammatory response, the concerted action of immune cells, and secreted mediators aimed to eradicate a microbial infection or to heal sterile tissue damage. Here, we first review how autophagy affects innate immune signaling, cell-autonomous immune defense, and adaptive immunity. Then, we discuss the role of non-canonical autophagy in microbial infections and inflammation. Finally, we review how crosstalk between autophagy and inflammation influences infectious, metabolic, and autoimmune disorders.

Cannabinoids and Chronic Liver Diseases

Nonalcoholic fatty liver disease (NAFLD), alcohol-induced liver disease (ALD), and viral hepatitis are the main causes of morbidity and mortality related to chronic liver diseases (CLDs) worldwide. New therapeutic approaches to prevent or reverse these liver disorders are thus emerging. Although their etiologies differ, these CLDs all have in common a significant dysregulation of liver metabolism that is closely linked to the perturbation of the hepatic endocannabinoid system (eCBS) and inflammatory pathways. Therefore, targeting the hepatic eCBS might have promising therapeutic potential to overcome CLDs. Experimental models of CLDs and observational studies in humans suggest that cannabis and its derivatives may exert hepatoprotective effects against CLDs through diverse pathways. However, these promising therapeutic benefits are not yet fully validated, as the few completed clinical trials on phytocannabinoids, which are thought to hold the most promising therapeutic potential (cannabidiol or tetrahydrocannabivarin), remained inconclusive. Therefore, expanding research on less studied phytocannabinoids and their derivatives, with a focus on their mode of action on liver metabolism, might provide promising advances in the development of new and original therapeutics for the management of CLDs, such as NAFLD, ALD, or even hepatitis C-induced liver disorders.

Differential Effects of D9 Tetrahydrocannabinol (THC)- and Cannabidiol (CBD)-Based Cannabinoid Treatments on Macrophage Immune Function In Vitro and on Gastrointestinal Inflammation in a Murine Model

Phytocannabinoids possess a wide range of immune regulatory properties, mediated by the endocannabinoid system. Monocyte/macrophage innate immune cells express endocannabinoid receptors. Dysregulation of macrophage function is involved in the pathogenesis of different inflammatory diseases, including inflammatory bowel disease. In our research, we aimed to evaluate the effects of the phytocannabinoids D9 tetrahydrocannabinol (THC) and cannabidiol (CBD) on macrophage activation. Macrophages from young and aged C57BL/6 mice were activated in vitro in the presence of pure cannabinoids or cannabis extracts. The phenotype of the cells, nitric oxide (NO•) secretion, and cytokine secretion were examined. In addition, these treatments were administered to murine colitis model. The clinical statuses of mice, levels of colon infiltrating macrophages, and inflammatory cytokines in the blood, were evaluated. We demonstrated inhibition of macrophage NO• and cytokine secretion and significant effects on expression of cell surface molecules. In the murine model, clinical scores were improved and macrophage colon infiltration reduced following treatment. We identified higher activity of cannabis extracts as compared with pure cannabinoids. Each treatment had a unique effect on cytokine composition. Overall, our results establish that the effects of cannabinoid treatments differ. A better understanding of the reciprocal relationship between cannabinoids and immunity is essential to design targeted treatment strategies.

Role of cannabinoids and the endocannabinoid system in modulation of diabetic cardiomyopathy

Diabetic complications, chiefly seen in long-term situations, are persistently deleterious to a large extent, requiring multi-factorial risk reduction strategies beyond glycemic control. Diabetic cardiomyopathy is one of the most common deleterious diabetic complications, being the leading cause of mortality among diabetic patients. The mechanisms of diabetic cardiomyopathy are multi-factorial, involving increased oxidative stress, accumulation of advanced glycation end products (AGEs), activation of various pro-inflammatory and cell death signaling pathways, and changes in the composition of extracellular matrix with enhanced cardiac fibrosis. The novel lipid signaling system, the endocannabinoid system, has been implicated in the pathogenesis of diabetes and its complications through its two main receptors: Cannabinoid receptor type 1 and cannabinoid receptor type 2, alongside other components. However, the role of the endocannabinoid system in diabetic cardiomyopathy has not been fully investigated. This review aims to elucidate the possible mechanisms through which cannabinoids and the endocannabinoid system could interact with the pathogenesis and the development of diabetic cardiomyopathy. These mechanisms include oxidative/ nitrative stress, inflammation, accumulation of AGEs, cardiac remodeling, and autophagy. A better understanding of the role of cannabinoids and the endocannabinoid system in diabetic cardiomyopathy may provide novel strategies to manipulate such a serious diabetic complication.

Expression and Functions of the CB2 Receptor in Human Leukocytes

The cannabinoid CB₂ receptor was cloned from the promyeloid cell line HL-60 and is notably expressed in most, if not all leukocyte types. This relatively restricted localization, combined to the absence of psychotropic effects following its activation, make it an attractive drug target for inflammatory and autoimmune diseases. Therefore, there has been an increasing interest in the past decades to identify precisely which immune cells express the CB₂ receptor and what are the consequences of such activation. Herein, we provide new data on the expression of both CB₁ and CB₂ receptors by human blood leukocytes and discuss the impact of CB₂ receptor activation in human leukocytes. While the expression of the CB₂ mRNA can be detected in eosinophils, neutrophils, monocytes, B and T lymphocytes, this receptor is most abundant in human eosinophils and B lymphocytes. We also review the evidence obtained from primary human leukocytes and immortalized cell lines regarding the regulation of their functions by the CB₂ receptor, which underscore the urgent need to deepen our understanding of the CB₂ receptor as an immunoregulator in humans.

Anti-Inflammatory and Pro-Autophagy Effects of the Cannabinoid Receptor CB2R: Possibility of Modulation in Type 1 Diabetes

Type 1 diabetes mellitus (T1DM) is an autoimmune disease resulting from loss of insulin-secreting β-cells in islets of Langerhans. The loss of β-cells is initiated when self-tolerance to β-cell-derived contents breaks down, which leads to T cell-mediated β-cell damage and, ultimately, β-cell apoptosis. Many investigations have demonstrated the positive effects of antagonizing cannabinoid receptor 1 (CB1R) in metabolic diseases such as fatty liver disease, obesity, and diabetes mellitus, but the role of cannabinoid receptor 2 (CB2R) in such diseases is relatively unknown. Activation of CB2R is known for its immunosuppressive roles in multiple sclerosis, rheumatoid arthritis, Crohn’s, celiac, and lupus diseases, and since autoimmune diseases can share common environmental and genetic factors, we propose CB2R specific agonists may also serve as disease modifiers in diabetes mellitus. The CNR2 gene, which encodes CB2R protein, is the result of a gene duplication of CNR1, which encodes CB1R protein. This ortholog evolved rapidly after transitioning from invertebrates to vertebrate hundreds of million years ago. Human specific CNR2 isoforms are induced by inflammation in pancreatic islets, and a CNR2 nonsynonymous SNP (Q63R) is associated with autoimmune diseases. We collected evidence from the literature and from our own studies demonstrating that CB2R is involved in regulating the inflammasome and especially release of the cytokine interleukin 1B (IL-1β). Furthermore, CB2R activation controls intracellular autophagy and may regulate secretion of extracellular vesicles from adipocytes that participate in recycling of lipid droplets, dysregulation of which induces chronic inflammation and obesity. CB2R activation may play a similar role in islets of Langerhans. Here, we will discuss future strategies to unravel what roles, if any, CB2R modifiers potentially play in T1DM.

Genetic deletion of the cannabinoid receptors CB1 and CB2 enhances inflammation with diverging effects on skin wound healing in mice

AIMS

Inflammation during wound healing is both essential and critical for restoring tissue integrity. Participating cells secrete soluble factors to regulate the inflammatory phase and to induce the adjacent regenerative processes. If pro-inflammatory signals are overexpressed, the wound stagnates in the inflammatory phase, which decelerates regular wound healing. The endocannabinoid system is ascribed great significance in maintenance of tissue homeostasis. It mediates several effects through the cannabinoid receptors CB1 and CB2.

MAIN METHODS

In order to clarify the role of these receptors in wound healing, excisional wounds were created on wildtype and CB1 and CB2 knockout mice. The wound closure was analyzed over a period of 14 days, and cytokine concentrations of tissue homogenisates were measured by ELISA. MSCs were isolated from the animals' subcutaneous adipose tissue and analyzed for viability and differentiation capacity, in vitro.

KEY FINDINGS

Deletion of CB2 increased Interleukin (IL)-6 and tumor necrosis factor (TNF)-α but did not affect tissue regeneration. In CB1-deficient animals, wound closure was delayed during early phases of healing, which was accompanied by increased concentrations of monocyte chemoattractant protein (MCP)-1 and TNF-α. CB1 and CB2 knockout MSCs presented altered viability and differentiation capacity compared to wildtype MSCs. The CB1-deficient MSCs released high levels of MCP-1 upon stimulation with TNF-α and IL-1β.

SIGNIFICANCE

The data indicate that both cannabinoid receptors regulate inflammation, and this study emphasizes the important role of CB1 in wound repair. Furthermore, our findings suggest that the secretome of CB1-deficient MSCs may contribute to the wound healing delay, in vivo.

The Gut-Liver Axis in Chronic Liver Disease: A Macrophage Perspective

Chronic liver disease (CLD) is a growing health concern which accounts for two million deaths per year. Obesity, alcohol overconsumption, and progressive cholestasis are commonly characterized by persistent low-grade inflammation and advancing fibrosis, which form the basis for development of end-stage liver disease complications, including hepatocellular carcinoma. CLD pathophysiology extends to the intestinal tract and is characterized by intestinal dysbiosis, bile acid dysregulation, and gut barrier disruption. In addition, macrophages are key players in CLD progression and intestinal barrier breakdown. Emerging studies are unveiling macrophage heterogeneity and driving factors of their plasticity in health and disease. To date, in-depth investigation of how gut-liver axis disruption impacts the hepatic and intestinal macrophage pool in CLD pathogenesis is scarce. In this review, we give an overview of the role of intestinal and hepatic macrophages in homeostasis and gut-liver axis disruption in progressive stages of CLD.

CB2 Receptor Involvement in the Treatment of Substance Use Disorders

The pharmacological modulation of the cannabinoid receptor 2 (CB2r) has emerged as a promising potential therapeutic option in addiction. The purpose of this review was to determine the functional involvement of CB2r in the effects produced by drugs of abuse at the central nervous system (CNS) level by assessing evidence from preclinical and clinical studies. In rodents, several reports suggest the functional involvement of CB2r in the effects produced by drugs of abuse such as alcohol, cocaine, or nicotine. In addition, the discovery of CB2r in brain areas that are part of the reward system supports the relevance of CB2r in the field of addiction. Interestingly, animal studies support that the CB2r regulates anxiety and depression behavioral traits. Due to its frequent comorbidity with neuropsychiatric disorders, these pharmacological actions may be of great interest in managing SUD. Preliminary clinical trials are focused on exploring the therapeutic potential of modulating CB2r in treating addictive disorders. These promising results support the development of new pharmacological tools regulating the CB2r that may help to increase the therapeutic success in the management of SUD.

Hepatic Cannabinoid Signaling in the Regulation of Alcohol-Associated Liver Disease

PURPOSE

The endocannabinoid system has emerged as a key regulatory signaling pathway in the pathophysiology of alcohol-associated liver disease (ALD). More than 30 years of research have established different roles of endocannabinoids and their receptors in various aspects of liver diseases, such as steatosis, inflammation, and fibrosis. However, pharmacological applications of the endocannabinoid system for the treatment of ALD have not been successful because of psychoactive side effects, despite some beneficial effects. Thus, a more delicate and detailed elucidation of the mechanism linking the endocannabinoid system and ALD may be of paramount significance in efforts to apply the system to the treatment of ALD.

SEARCH METHODS

Three electronic databases (PubMed, MEDLINE, and Cochrane Library) were used for literature search from November 1988 to April 2021. Major keywords used for literature searches were “cannabinoid,” “cannabinoid receptor,” “ALD,” “steatosis,” and “fibrosis.”

SEARCH RESULTS

According to the inclusion and exclusion criteria, the authors selected 47 eligible full-text articles out of 2,691 searched initially. Studies in the past 3 decades revealed the opposite effects of cannabinoid receptors CB1R and CB2R on steatosis, inflammation, and fibrosis in ALD.

DISCUSSION AND CONCLUSIONS

This review summarizes the endocannabinoid signaling in the general physiology of the liver, the pathogenesis of ALD, and some of the potential therapeutic implications of cannabinoid-based treatments for ALD.

Macrophage autophagy protects against hepatocellular carcinogenesis in mice

Autophagy is a lysosomal degradation pathway of cellular components that regulates macrophage properties. Macrophages are critically involved in tumor growth, metastasis, angiogenesis and immune suppression. Here, we investigated whether macrophage autophagy may protect against hepatocellular carcinoma (HCC). Experiments were performed in mice with deletion of the autophagy gene Atg5 in the myeloid lineage (ATG5^Mye-/- mice) and their wild-type (WT) littermates. As compared to WT, ATG5^Mye-/- mice were more susceptible to diethylnitrosamine (DEN)-induced hepatocarcinogenesis, as shown by enhanced tumor number and volume. Moreover, DEN-treated ATG5^Mye-/- mice exhibited compromised immune cell recruitment and activation in the liver, suggesting that macrophage autophagy invalidation altered the antitumoral immune response. RNA sequencing showed that autophagy-deficient macrophages sorted from DEN mice are characterized by an enhanced expression of immunosuppressive markers. In vitro studies demonstrated that hepatoma cells impair the autophagy flux of macrophages and stimulate their expression of programmed cell death-ligand 1 (PD-L1), a major regulator of the immune checkpoint. Moreover, pharmacological activation of autophagy reduces hepatoma cell-induced PD-L1 expression in cultured macrophages while inhibition of autophagy further increases PD-L1 expression suggesting that autophagy invalidation in macrophages induces an immunosuppressive phenotype. These results uncover macrophage autophagy as a novel protective pathway regulating liver carcinogenesis.

Cannabinoid Type-2 Receptor Agonist, JWH133 May Be a Possible Candidate for Targeting Infection, Inflammation, and Immunity in COVID-19

The COVID-19 pandemic, caused by SARS-CoV-2, is a deadly disease affecting millions due to the non-availability of drugs and vaccines. The majority of COVID-19 drugs have been repurposed based on antiviral, immunomodulatory, and antibiotic potential. The pathogenesis and advanced complications with infection involve the immune-inflammatory cascade. Therefore, a therapeutic strategy could reduce infectivity, inflammation, and immune modulation. In recent years, modulating the endocannabinoid system, particularly activation of the cannabinoid type 2 (CB2) receptor is a promising therapeutic target for modulation of immune-inflammatory responses. JWH133, a selective, full functional agonist of the CB2 receptor, has been extensively studied for its potent anti-inflammatory, antiviral, and immunomodulatory properties. JWH133 modulates numerous signaling pathways and inhibits inflammatory mediators, including cytokines, chemokines, adhesion molecules, prostanoids, and eicosanoids. In this study, we propose that JWH133 could be a promising candidate for targeting infection, immunity, and inflammation in COVID-19, due to its pharmacological and molecular mechanisms in numerous preclinical efficacy and safety studies, along with its immunomodulatory, anti-inflammatory, organoprotective, and antiviral properties. Thus, JWH133 should be investigated in preclinical and clinical studies for its potential as an agent or adjuvant with other agents for its effect on viremia, infectivity, immune modulation, resolution of inflammation, reduction in severity, and progression of complications in COVID-19. JWH133 is devoid of psychotropic effects due to CB2 receptor selectivity, has negligible toxicity, good bioavailability and druggable properties, including pharmacokinetic and physicochemical effects. We believe that JWH133 could be a promising drug and may inspire further studies for an evidence-based approach against COVID-19.

Pharmacological Properties, Therapeutic Potential and Molecular Mechanisms of JWH133, a CB2 Receptor-Selective Agonist

The endocannabinoid system has attracted attention as a pharmacological target for several pathological conditions. Cannabinoid (CB2)-selective agonists have been the focus of pharmacological studies because modulation of the CB2 receptor (CB2R) can be useful in the treatment of pain, inflammation, arthritis, addiction, and cancer among other possible therapeutic applications while circumventing CNS-related adverse effects. Increasing number of evidences from different independent preclinical studies have suggested new perspectives on the involvement of CB2R signaling in inflammation, infection and immunity, thus play important role in cancer, cardiovascular, renal, hepatic and metabolic diseases. JWH133 is a synthetic agonist with high CB2R selectivity and showed to exert CB2R mediated antioxidant, anti-inflammatory, anticancer, cardioprotective, hepatoprotective, gastroprotective, nephroprotective, and immunomodulatory activities. Cumulative evidences suggest that JWH133 protects against hepatic injury, renal injury, cardiotoxicity, fibrosis, rheumatoid arthritis, and cancer as well as against oxidative damage and inflammation, inhibits fibrosis and apoptosis, and acts as an immunosuppressant. This review provides a comprehensive overview of the polypharmacological properties and therapeutic potential of JWH133. This review also presents molecular mechanism and signaling pathways of JWH133 under various pathological conditions except neurological diseases. Based on the available data, this review proposes the possibilities of developing JWH133 as a promising therapeutic agent; however, further safety and toxicity studies in preclinical studies and clinical trials in humans are warranted.

Autophagy in liver diseases: A review

The liver is a highly dynamic metabolic organ that plays critical roles in plasma protein synthesis, gluconeogenesis and glycogen storage, cholesterol metabolism and bile acid synthesis as well as drug/xenobiotic metabolism and detoxification. Research from the past decades indicate that autophagy, the cellular catabolic process mediated by lysosomes, plays an important role in maintaining cellular and metabolic homeostasis in the liver. Hepatic autophagy fluctuates with hormonal cues and the availability of nutrients that respond to fed and fasting states as well as circadian activities. Dysfunction of autophagy in liver parenchymal and non-parenchymal cells can lead to various liver diseases including non-alcoholic fatty liver diseases, alcohol associated liver disease, drug-induced liver injury, cholestasis, viral hepatitis and hepatocellular carcinoma. Therefore, targeting autophagy may be a potential strategy for treating these various liver diseases. In this review, we will discuss the current progress on the understanding of autophagy in liver physiology. We will also discuss several forms of selective autophagy in the liver and the molecular signaling pathways in regulating autophagy of different cell types and their implications in various liver diseases.

LC3-associated phagocytosis protects against inflammation and liver fibrosis via immunoreceptor inhibitory signaling

Sustained hepatic and systemic inflammation, particularly originating from monocytes/macrophages, is a driving force for fibrosis progression to end-stage cirrhosis and underlies the development of multiorgan failure. Reprogramming monocyte/macrophage phenotype has emerged as a strategy to limit inflammation during chronic liver injury. Here, we report that LC3-associated phagocytosis (LAP), a noncanonical form of autophagy, protects against hepatic and systemic inflammation during chronic liver injury in rodents, with beneficial antifibrogenic effects. LAP is enhanced in blood and liver monocytes from patients with fibrosis and cirrhosis. Pharmacological inhibition of LAP components in human monocytes from patients with cirrhosis or genetic disruption of LAP in mice with chronic liver injury exacerbates both the inflammatory signature in isolated human monocytes and the hepatic inflammatory profile in mice, resulting in enhanced liver fibrosis. Mechanistically, patients with cirrhosis showed increased monocyte expression of Fc fragment of IgG receptor IIA (FcγRIIA) and enhanced engulfment of immunoglobulin G in LC3⁺ phagosomes that triggers an FcγRIIA/Src homology region 2 domain-containing phosphatase-1 (SHP-1) inhibitory immunoreceptor tyrosine-based activation motif (ITAMi) anti-inflammatory pathway. Mice overexpressing human FcγRIIA in myeloid cells show enhanced LAP in response to chronic liver injury and resistance to inflammation and liver fibrosis. Activation of LAP is lost in monocytes from patients with multiorgan failure and restored by specifically targeting ITAMi signaling with anti-FcγRIIA F(ab')₂ fragments, or with intravenous immunoglobulin (IVIg). These data suggest the existence of an ITAMi-mediated mechanism by which LAP might protect against inflammation. Sustaining LAP may open therapeutic perspectives for patients with chronic liver disease.

Induced Autophagy of Macrophages and the Regulation of Inflammatory Effects by Perovskite Nanomaterial LaNiO3

Perovskite nanomaterials (NMs) possess excellent physicochemical properties and have promising applications in light-emitting diodes (LEDs), lasers, photodetectors, and artificial synapse electronics. Potential exposure to these NMs happens in the manufacture and application of the perovskite-based products, however, the biological safety of these NMs is still unknown. Here, we used the LaNiO₃ NM (LNO), a typical kind of perovskite nanostructures to study the interaction with macrophages (J774A.1) and to explore its biological effects at the cellular level. Firstly, we characterized the properties of LNO including the size, shape, and crystal structure using Transmission electronic microscope (TEM), Dynamic lighting scattering (DLS), and X-ray diffraction (XRD). Secondly, to gain a better understanding of the biological effect, we evaluated the effect of LNO on cell viability and found that LNO induced cell autophagy at a concentration of 5 μg/ml and influenced the inflammatory response based on RT-PCR result. Finally, we demonstrated the mechanism that LNO causes cell autophagy and immune response is probably due to the metal ions released from LNO in acidic lysosomes, which triggered ROS and increased lysosomal membrane permeation. This study indicates the safety aspect of perovskite NMs and may guide the rational design of perovskite NMs with more biocompatibility during their manufacture and application.

Potential roles of natural products in the targeting of proteinopathic neurodegenerative diseases

Defective proteostasis is associated with the gradual accumulations of misfolded proteins and is a hallmark of many age-associated neurodegenerative diseases. In the aged brain, maintenance of the proteostasis network presents a substantial challenge, and its loss contributes to the onset and progression of neurological diseases associated with cognitive decline due to the generation of toxic protein aggregates, a process termed 'proteinopathy'. Emerging evidence suggests that reversing proteinopathies by boosting proteostasis might provide an effective means of preventing neurodegeneration. From this perspective, phytochemicals may play significant roles as potent modulators of the proteostasis network, as previous reports have suggested they can interact with various network components to modify pathologies and confer neuroprotection. This review focuses on some potent phytochemicals that directly or indirectly modulate the proteostasis network and on their possible molecular targets. In addition, we propose strategies for the natural product-based modulation of proteostasis machinery that target proteinopathies.

Novel indirect co-culture of immortalised hepatocytes with monocyte derived macrophages is characterised by pro-inflammatory cytokine networks

The liver is composed of different cell populations. Interactions of different cell populations can be investigated by a newly established indirect co-culture system consisting of immortalised primary human hepatocytes and human monocyte derived macrophages (MDMs). Using the time-dependent cytokine secretion of the co-cultures and single cultures, correlation networks (including the cytokines G-CSF, CCL3, MCP-1, CCL20, FGF, TGF-β1, GM-CSF, IL-8 IL-6, IL-1β, and IL-18) were generated and the correlations were validated by application of IL-8 and TNF-α-neutralising antibodies. The data reveal that IL-8 is crucial for the interaction between hepatocytes and macrophages in vitro. In addition, transcriptome analyses showed that a change in the ratio between macrophages and hepatocytes may trigger pro-inflammatory signalling pathways of the acute phase response and the complement system (release of, e.g., certain cyto- and chemokines). Using diclofenac and LPS showed that the release of cytokines is increasing with higher ratios of MDMs. Altogether, we could demonstrate that the current co-culture system is better suited to mirror the in vivo situation when compared to previously established co-culture systems composed of HepG2 and differentiated THP-1 cells. Further, our data reveal that the cytokine IL-8 is crucial for the interaction between hepatocytes and macrophages in vitro.

Signaling through the type 2 cannabinoid receptor regulates the severity of acute and chronic graft-versus-host disease

Graft-versus-host disease (GVHD) pathophysiology is a complex interplay between cells that comprise the adaptive and innate arms of the immune system. Effective prophylactic strategies are therefore contingent upon approaches that address contributions from both immune cell compartments. In the current study, we examined the role of the type 2 cannabinoid receptor (CB2R), which is expressed on nearly all immune cells, and demonstrated that absence of the CB2R on donor CD4+ or CD8+ T cells or administration of a selective CB2R pharmacological antagonist exacerbated acute GVHD lethality. This was accompanied primarily by the expansion of proinflammatory CD8+ T cells, indicating that constitutive CB2R expression on T cells preferentially regulated CD8+ T-cell alloreactivity. Using a novel CB2ReGFP reporter mouse, we observed significant loss of CB2R expression on T cells, but not macrophages, during acute GVHD, indicative of differential alterations in receptor expression under inflammatory conditions. Therapeutic targeting of the CB2R with the agonists Δ9-tetrahydrocannabinol (THC) and JWH-133 revealed that only THC mitigated lethal T cell-mediated acute GVHD. Conversely, only JWH-133 was effective in a sclerodermatous chronic GVHD model where macrophages contributed to disease biology. In vitro, both THC and JWH-133 induced arrestin recruitment and extracellular regulated kinase phosphorylation via CB2R, but THC had no effect on CB2R-mediated inhibition of adenylyl cyclase. This study shows that the CB2R plays a critical role in the regulation of GVHD and suggests that effective therapeutic targeting is dependent upon agonist signaling characteristics and receptor selectivity in conjunction with the composition of pathogenic immune effector cells.

Cannabinoid Receptors in Metabolic Regulation and Diabetes

There is an urgent need for developing effective drugs to combat the obesity and Type 2 diabetes mellitus epidemics. The endocannabinoid system plays a major role in energy homeostasis. It comprises the cannabinoid receptors 1 and 2 (CB₁ and CB₂), endogenous ligands called endocannabinoids and their metabolizing enzymes. Because the CB₁ receptor is overactivated in metabolic alterations, pharmacological blockade of the CB₁ receptor arose as a promising candidate to treat obesity. However, because of the wide distribution of CB₁ receptors in the central nervous system, their negative central effects halted further therapeutic use. Although the CB₂ receptor is mostly peripherally expressed, its role in metabolic homeostasis remains unclear. This review discusses the potential of CB₁ and CB₂ receptors at the peripheral level to be therapeutic targets in metabolic diseases. We focus on the impact of pharmacological intervention and/or silencing on peripheral cannabinoid receptors in organs/tissues relevant for energy homeostasis. Moreover, we provide a perspective on novel therapeutic strategies modulating these receptors. Targeting CB₁ with peripherally restricted antagonists, neutral antagonists, inverse agonists, or monoclonal antibodies could represent successful strategies. CB₂ agonism has shown promising results at preclinical level. Beyond classic antagonism and agonism targeting orthosteric sites, the recently described crystal structures of CB₁ and CB₂ open new possibilities for therapeutic interventions with negative and positive allosteric modulators. The challenge of simultaneously targeting CB₁ and CB₂ might be possible by developing dual-steric ligands. The future will tell whether these promising strategies result in a renaissance of the cannabinoid receptors as therapeutic targets in metabolic diseases.

Autophagy in liver diseases

Autophagy is the liver cell energy recycling system regulating a variety of homeostatic mechanisms. Damaged organelles, lipids and proteins are degraded in the lysosomes and their elements are re-used by the cell. Investigations on autophagy have led to the award of two Nobel Prizes and a health of important reports. In this review we describe the fundamental functions of autophagy in the liver including new data on the regulation of autophagy. Moreover we emphasize the fact that autophagy acts like a two edge sword in many occasions with the most prominent paradigm being its involvement in the initiation and progress of hepatocellular carcinoma. We also focused to the implication of autophagy and its specialized forms of lipophagy and mitophagy in the pathogenesis of various liver diseases. We analyzed autophagy not only in well studied diseases, like alcoholic and nonalcoholic fatty liver and liver fibrosis but also in viral hepatitis, biliary diseases, autoimmune hepatitis and rare diseases including inherited metabolic diseases and also acetaminophene hepatotoxicity. We also stressed the different consequences that activation or impairment of autophagy may have in hepatocytes as opposed to Kupffer cells, sinusoidal endothelial cells or hepatic stellate cells. Finally, we analyzed the limited clinical data compared to the extensive experimental evidence and the possible future therapeutic interventions based on autophagy manipulation.

Obesity, Diabetes, Coffee, Tea, and Cannabis Use Alter Risk for Alcohol-Related Cirrhosis in 2 Large Cohorts of High-Risk Drinkers

INTRODUCTION

Sustained high alcohol intake is necessary but not sufficient to produce alcohol-related cirrhosis. Identification of risk factors, apart from lifetime alcohol exposure, would assist in discovery of mechanisms and prediction of risk.

METHODS

We conducted a multicenter case-control study (GenomALC) comparing 1,293 cases (with alcohol-related cirrhosis, 75.6% male) and 754 controls (with equivalent alcohol exposure but no evidence of liver disease, 73.6% male). Information confirming or excluding cirrhosis, and on alcohol intake and other potential risk factors, was obtained from clinical records and by interview. Case-control differences in risk factors discovered in the GenomALC participants were validated using similar data from 407 cases and 6,573 controls from UK Biobank.

RESULTS

The GenomALC case and control groups reported similar lifetime alcohol intake (1,374 vs 1,412 kg). Cases had a higher prevalence of diabetes (20.5% (262/1,288) vs 6.5% (48/734), P = 2.27 × 10-18) and higher premorbid body mass index (26.37 ± 0.16 kg/m2) than controls (24.44 ± 0.18 kg/m2, P = 5.77 × 10-15). Controls were significantly more likely to have been wine drinkers, coffee drinkers, smokers, and cannabis users than cases. Cases reported a higher proportion of parents who died of liver disease than controls (odds ratio 2.25 95% confidence interval 1.55-3.26). Data from UK Biobank confirmed these findings for diabetes, body mass index, proportion of alcohol as wine, and coffee consumption.

DISCUSSION

If these relationships are causal, measures such as weight loss, intensive treatment of diabetes or prediabetic states, and coffee consumption should reduce the risk of alcohol-related cirrhosis.

Deciphering the cellular mechanisms underlying fibrosis-associated diseases and therapeutic avenues

Fibrosis is the excessive deposition of extracellular matrix components, which results in disruption of tissue architecture and loss of organ function. Fibrosis leads to high morbidity and mortality worldwide, mainly due to the lack of effective therapeutic strategies against fibrosis. It is generally accepted that fibrosis occurs during an aberrant wound healing process and shares a common pathogenesis across different organs such as the heart, liver, kidney, and lung. A better understanding of the fibrosis-related cellular and molecular mechanisms will be helpful for development of targeted drug therapies. Extensive studies revealed that numerous mediators contributed to fibrogenesis, suggesting that targeting these mediators may be an effective therapeutic strategy for antifibrosis. In this review, we describe a number of mediators involved in tissue fibrosis, including aryl hydrocarbon receptor, Yes-associated protein, cannabinoid receptors, angiopoietin-like protein 2, high mobility group box 1, angiotensin-converting enzyme 2, sphingosine 1-phosphate receptor-1, SH2 domain-containing phosphatase-2, and long non-coding RNAs, with the goal that drugs targeting these important mediators might exhibit a beneficial effect on antifibrosis. In addition, these mediators show profibrotic effects on multiple tissues, suggesting that targeting these mediators will exert antifibrotic effects on different organs. Furthermore, we present a variety of compounds that exhibit therapeutic effects against fibrosis. This review suggests therapeutic avenues for targeting organ fibrosis and concurrently identifies challenges and opportunities for designing new therapeutic strategies against fibrosis.

Programmed cell death in alcohol-associated liver disease

Alcohol-associated liver disease (ALD), which ranges from mild disease to alcohol-associated hepatitis and cirrhosis, is the most prevalent type of chronic liver disease and a leading cause of morbidity and mortality worldwide. Accumulating evidence reveals that programmed cell death (PCD) plays a crucial role in progression of ALD involving crosstalk between hepatocytes and immune cells. Multiple pathways of PCD, including apoptosis, necroptosis, autophagy, pyroptosis and ferroptosis, are reported in ALD. Interestingly, PCD pathways are intimately linked and interdependent, making it difficult to therapeutically target a single pathway. This review clarifies the multiple types of PCD occurring in liver and focuses on crosstalk between hepatocytes and innate immune cells in ALD.

Animal models for liver disease - A practical approach for translational research

Animal models are crucial for improving our understanding of human pathogenesis, enabling researchers to identify therapeutic targets and test novel drugs. In the current review, we provide a comprehensive summary of the most widely used experimental models of chronic liver disease, starting from early stages of fatty liver disease (non-alcoholic and alcoholic) to steatohepatitis, advanced cirrhosis and end-stage primary liver cancer. We focus on aspects such as reproducibility and practicality, discussing the advantages and weaknesses of available models for researchers who are planning to perform animal studies in the near future. Additionally, we summarise current and prospective models based on human tissue bioengineering.

Interactions Between Alcohol and the Endocannabinoid System

Endocannabinoids are lipid mediators that interact with the same cannabinoid receptors that recognize Δ⁹ -tetrahydrocannabinol (THC), the psychoactive constituent of marijuana, to induce similar effects in the brain and periphery. Alcohol and THC are both addictive substances whose acute use elicits rewarding effects that can lead to chronic and compulsive use via engaging similar signaling pathways in the brain. In the liver, both alcohol and endocannabinoids activate lipogenic gene expression leading to fatty liver disease. This review focuses on evidence accumulated over the last 2 decades to indicate that both the addictive neural effects of ethanol and its organ toxic effects in the liver and elsewhere are mediated, to a large extent, by endocannabinoids signaling via cannabinoid-1 receptors (CB₁ R). The therapeutic potential of CB₁ R blockade globally or in peripheral tissues only is also discussed.

Macrophage Phenotype and Function in Liver Disorder

Hepatic macrophages are a remarkably heterogeneous population consisting of self-renewing tissue-resident phagocytes, termed Kupffer cells (KCs), and recruited macrophages derived from peritoneal cavity as well as the bone marrow. KCs are located in the liver sinusoid where they scavenge the microbe from the portal vein to maintain liver homeostasis. Liver injury may trigger hepatic recruitment of peritoneal macrophages and monocyte-derived macrophages. Studies describing macrophage accumulation have shown that hepatic macrophages are involved in the initiation and progression of various liver diseases. They act as tolerogenic antigen-presenting cells to inhibit T-cell activation by producing distinct sets of cytokines, chemokines, and mediators to maintain or resolve inflammation. Furthermore, by releasing regenerative growth factors, matrix metalloproteinase arginase, they promote tissue repair. Recent experiments found that KCs and recruited macrophages may play different roles in the development of liver disease. Given that hepatic macrophages are considerably plastic populations, their phenotypes and functions are likely switching along disease progression. In this review, we summarize current knowledge about the role of tissue-resident macrophages and recruited macrophages in pathogenesis of alcoholic liver disease (ALD), non-alcoholic steatohepatitis (NASH), viral hepatitis, and hepatocellular carcinoma (HCC).

Role of autophagy in alcohol and drug-induced liver injury

Alcohol-related liver disease (ALD) and drug-induced liver injury (DILI) are common causes of severe liver disease, and successful treatments are lacking. Autophagy plays a protective role in both ALD and DILI by selectively removing damaged mitochondria (mitophagy), lipid droplets (lipophagy), protein aggregates and adducts in hepatocytes. Autophagy also protects against ALD by degrading interferon regulatory factor 1 (IRF1) and damaged mitochondria in hepatic macrophages. Specifically, we will discuss selective autophagy for removal of damaged mitochondria and lipid droplets in hepatocytes and autophagy-mediated degradation of IRF1 in hepatic macrophages as protective mechanisms against alcohol-induced liver injury and steatosis. In addition, selective autophagy for removal of damaged mitochondria and protein adducts for protection against DILI is discussed in this review. Development of new therapeutics for ALD and DILI is greatly needed, and selective autophagy pathways may provide promising targets. Drug and alcohol effects on autophagy regulation as well as protective mechanisms of autophagy against DILI and ALD are highlighted in this review.

Cannabinoid receptor 2 promotes the intracellular degradation of HMGB1 via the autophagy-lysosome pathway in macrophage

High mobility group box 1 (HMGB1) is a late phase inflammatory mediator in many inflammatory diseases. Extracellular HMGB1 could bind to many membrane receptors to activate downstream signaling molecules and promote inflammation resulting in cell and tissue damage. In our previous work, we found cannabinoid receptor Ⅱ(CB2R) inhibited the expression of HMGB1 in lipopolysaccharide (LPS)-induced septic models in vivo and in vitro, but the underlying mechanism is still unclear. The present study was aimed to explore the possible pathway through which CB2R suppressed HMGB1. Here, we found that the specific agonist of CB2R, GW405833 (GW) could induce intracellular HMGB1 degradation without influencing HMGB1 mRNA in peritoneal macrophages. Then we observed that autophagy inhibitor 3-methyladenine (3-MA) but not proteasome inhibitor MG-132 (MG) could block GW-induced HMGB1 degradation, which indicated that the autophagy-lysosome but not the ubiquitination pathway was involved in this process. Further study showed that GW could promote the integrity of autophagy flux in macrophages in terms of increased level of LC3Ⅱand decreased expression of p62 protein. It also observed that inhibition of autophagy blocked GW-induced nuclear translocation of HMGB1 in macrophages. GW could up-regulate expression of Cathepsin B (CTSB), and inhibition of CTSB blocked GW-induced HMGB1 degradation. In summary, all the data showed that activation of CB2R could promote the intracellular degradation of HMGB1 via the autophagy-lysosome pathway in macrophage.

Aryl Hydrocarbon Receptor Contributes to the Transcriptional Program of IL-10-Producing Regulatory B Cells

Regulatory B cells (Bregs) play a critical role in the control of autoimmunity and inflammation. IL-10 production is the hallmark for the identification of Bregs. However, the molecular determinants that regulate the transcription of IL-10 and control the Breg developmental program remain unknown. Here, we demonstrate that aryl hydrocarbon receptor (AhR) regulates the differentiation and function of IL-10-producing CD19+CD21hiCD24hiBregs and limits their differentiation into B cells that contribute to inflammation. Chromatin profiling and transcriptome analyses show that loss of AhR in B cells reduces expression of IL-10 by skewing the differentiation of CD19+CD21hiCD24hiB cells into a pro-inflammatory program, under Breg-inducing conditions. B cell AhR-deficient mice develop exacerbated arthritis, show significant reductions in IL-10-producing Bregs and regulatory T cells, and show an increase in T helper (Th) 1 and Th17 cells compared with B cell AhR-sufficient mice. Thus, we identify AhR as a relevant contributor to the transcriptional regulation of Breg differentiation.

Protective effects of specific cannabinoid receptor 2 agonist GW405833 on concanavalin A-induced acute liver injury in mice

Cannabinoid receptor 2 (CB2R) is highly expressed in immune cells and plays an important role in regulating immune responses. In the current study, we investigated the effects of GW405833 (GW), a specific CB2R agonist, on acute liver injury induced by concanavalin A (Con A). In animal experiments, acute liver injury was induced in mice by injection of Con A (20 mg/kg, i.v.). The mice were treated with GW (20 mg/kg, i.p., 30 min after Con A injection) or GW plus the selective CB2R antagonist AM630 (2 mg/kg, i.p., 15 min after Con A injection). We found that Con A caused severe acute liver injury evidenced by significantly increased serum aminotransferase levels, massive hepatocyte apoptosis, and necrosis, as well as lymphocyte infiltration in liver tissues. Treatment with GW significantly ameliorated Con A-induced pathological injury in liver tissue, decreased serum aminotransferase levels, and decreased hepatocyte apoptosis. The therapeutic effects of GW were prevented by AM630. In cell experiments, we showed that CB2Rs were highly expressed in Jurkat T cells, but little expression in L02 liver cells. Treatment with GW (10-40 μg/mL) dose-dependently decreased the viability of Jurkat T cells and induced cell apoptosis, which was reversed by AM630. In the coculture of Jurkat T cells with L02 liver cells, GW dose-dependently protected L02 cells from apoptosis induced by Con A (5 μg/mL). The protective effect of GW was reversed by AM630 (1 μg/mL). Our results suggest that GW protects against Con A-induced acute liver injury in mice by inhibiting Jurkat T-cell proliferation through the CB2Rs.

Cannabinoid receptor 2‑selective agonist JWH015 attenuates bone cancer pain through the amelioration of impaired autophagy flux induced by inflammatory mediators in the spinal cord

Bone cancer pain (BCP) is a severe complication of advanced bone cancer. Although cannabinoid receptor 2 (CB2) agonists may have an analgesic effect, the underlying mechanism remains unclear. CB2 serves a protective role in various pathological states through the activation of autophagy. Therefore, the present study aimed to determine whether the analgesic effects of the selective CB2 agonist JWH015 was mediated by the activation of autophagy in BCP. BCP was induced by the intra‑femur implantation of NCTC2472 fibrosarcoma cells in C3H/HeN mice. The pain behaviors were assessed on the following postoperative days. The selective CB2 agonist JWH015 (1 and 2 µg) was intrathecally administered on day 14 following implantation. AM630 (1 µg), a CB2 antagonist, was injected 30 min before JWH015 administration. Lipopolysaccharide (LPS; 100 nM)‑stimulated primary neurons were treated with JWH015 (1 µM) and AM630 (1 µM) to further verify the mechanism by which CB2 affects autophagy. The results demonstrated that autophagy flux was impaired in spinal neurons during BCP, as indicated by the increased ratio of microtubule‑associated protein 1 light chain 3β (LC3B)‑II/LC3B‑I and increased expression of p62. Intrathecal administration of JWH015 attenuated BCP, which was accompanied by the amelioration of impaired autophagy flux (decreased LC3B‑II/LC3B‑I ratio and decreased p62expression). In addition, the activation of glia cells and upregulation of the glia‑derived inflammatory mediators, interleukin (IL)‑1β and IL‑6 were suppressed by JWH015. In LPS‑stimulated primary neurons, IL‑1β and IL‑6 were increased, and autophagy flux was impaired; whereas treatment with JWH015 decreased the expression of IL‑1β and IL‑6, LC3B‑II/LC3B‑I ratio and expression of p62. These effects were by pretreatment with the CB2‑selective antagonist AM630. The results of the present study suggested that the impairment of autophagy flux was induced by glia‑derived inflammatory mediators in spinal neurons. Intrathecal administration of the selective CB2 agonist JWH015 ameliorated autophagy flux through the downregulation of IL‑1β and IL‑6 and attenuated BCP.

Autophagy, Metabolism, and Alcohol-Related Liver Disease: Novel Modulators and Functions

Alcohol-related liver disease (ALD) is caused by over-consumption of alcohol. ALD can develop a spectrum of pathological changes in the liver, including steatosis, inflammation, cirrhosis, and complications. Autophagy is critical to maintain liver homeostasis, but dysfunction of autophagy has been observed in ALD. Generally, autophagy is considered to protect the liver from alcohol-induced injury and steatosis. In this review, we will summarize novel modulators of autophagy in hepatic metabolism and ALD, including autophagy-mediating non-coding RNAs (ncRNAs), and crosstalk of autophagy machinery and nuclear factors. We will also discuss novel functions of autophagy in hepatocytes and non-parenchymal hepatic cells during the pathogenesis of ALD and other liver diseases.