Cannabidiol alleviates carbon tetrachloride-induced liver fibrosis in mice by regulating NF-κB and PPAR-α pathways.

Liver fibrosis has become a serious public health problem that can develop into liver cirrhosis and hepatocellular carcinoma and even lead to death. Cannabidiol (CBD), which is an abundant nonpsychoactive component in the cannabis plant, exerts cytoprotective effects in many diseases and under pathological conditions. In our previous studies, CBD significantly attenuated liver injury induced by chronic and binge alcohol in a mouse model and oxidative bursts in human neutrophils. However, the effects of CBD on liver fibrosis and the underlying mechanisms still need to be further explored. A mouse liver fibrosis model was induced by carbon tetrachloride (CCl4) for 10 weeks and used to explore the protective properties of CBD and related molecular mechanisms. After the injection protocol, serum samples and livers were used for molecular biology, biochemical and pathological analyses. The results showed that CBD could effectively improve liver function and reduce liver damage and liver fibrosis progression in mice; the expression levels of transaminase and fibrotic markers were reduced, and histopathological characteristics were improved. Moreover, CBD inhibited the levels of inflammatory cytokines and reduced the protein expression levels of p-NF-κB, NF-κB, p-IκBα, p-p38 MAPK, and COX-2 but increased the expression level of PPAR-α. We found that CBD-mediated protection involves inhibiting NF-κB and activating PPAR-α. In conclusion, these results suggest that the hepatoprotective effects of CBD may be due to suppressing the inflammatory response in CCl4-induced mice and that the NF-κB and PPAR-α signaling pathways might be involved in this process.

Cannabidiol regulates the activation of hepatic stellate cells by modulating the NOX4 and NF-κB pathways.

Cannabidiol (CBD) is an extract of natural cannabinoids that has therapeutic implications for a variety of ailments, such as neurological diseases, cardiomyopathy, and diabetes, due to its strong anti-inflammatory and oxidative stress properties. Our purpose was to reveal the possible underlying mechanisms and effect of CBD on the glucose oxidase (GO)-induced activation of HSC-T6 and LX-2 cells. The results showed that CBD effectively inhibited the proliferation and activation of HSC-T6 and LX-2 cells, and reduced the production of profibrotic factors to different degrees. CBD disrupted the NOX4 signalling pathway in activated HSC-T6 and LX-2 cells, reduced ROS and MDA levels, and increased SOD and GSH levels, thereby stabilizing the oxidative imbalance. CBD significantly inhibited the phosphorylation and degradation of NF-κB and IκBα, and decreased the release of TNF-α, IL-1ß and IL-6. Moreover, CBD and an NF-κB-specific inhibitor (CAPE) effectively inhibited the expression of α-SMA, COL I, TNF-α and IL-1ß to promote collagen metabolism and inhibit the inflammatory response. Overall, CBD inhibited HSCs activation through a and the mechanism involving the inhibition of NOX4 and NF-κB-dependent ROS regulation, thereby reducing inflammation and ameliorating oxidative imbalances.

The protective effect of cannabinoid type II receptor agonist AM1241 on ConA-induced liver injury in mice via mitogen-activated protein kinase signalling pathway.

INTRODUCTION: The endocannabinoid system plays an important role in regulating the immune responses in inflammation. At present, there are no good clinical drugs for many immune liver diseases. METHODS: We explored the protective effect of the cannabinoid type II (CB2) receptor agonist AM1241 on the liver of mice with acute liver injury caused by concanavalin from the perspective of inflammation and immunity. Pathological evaluation in hepatic tissue was examined by haematoxylin and eosin (HE) staining and the levels of biochemical parameters in the serum were measured by automatic biochemical analysis. The content of inflammatory factors was measured by enzyme-linked immunosorbent assay and real-time quantitative reverse transcription polymerase chain reaction (real-time PCR). The liver apoptosis-related proteins were observed by immunohistochemistry. The expression of liver injury-related proteins was analysed by Western blot. Immune cells were isolated from the liver of mice and studied in vitro. RESULTS: Reduced levels of alanine transaminase and aspartate transaminase were observed in ConA-induced liver injury mice treated with AM1241, together with attenuated liver damage evidenced by H&E staining. Moreover, AM1241 inhibited the protein and gene expression levels of TNF-α, IL-6 and IFN-γ in the livers of mice. The phosphorylation levels of p38, JNK, ERK1/2, P65 and cAMP response element-binding protein (CREB) in the mouse were significantly reduced in AM1241 pretreatment, while the level of p-JNK increased. In addition, the P/T-P65 and P/T-CREB of the AM1241 pretreatment group were significantly reduced. The results of immunohistochemistry measurement are consistent with those of Western blotting. The CB2-mediated effect is through macrophage-like Kupffer cells. CONCLUSION: Our study suggests that the ConA-induced liver injury model in mice is protected by CB2 agonist AM1241 by modulation of CB2 receptor-rich immune cells, for example, Kupffer cells. Reduced inflammatory responses regulate apoptosis/cell death in the liver particularly hepatocytes and other parenchymal cells.

Knockout of the Cannabinoid Receptor 2 Gene Promotes Inflammation and Hepatic Stellate Cell Activation by Promoting A20/Nuclear Factor-κB (NF-κB) Expression in Mice with Carbon Tetrachloride-Induced Liver Fibrosis.

BACKGROUND This study aimed to investigate the effect of deleting the cannabinoid receptor 2 (CB2) gene on the development of hepatic fibrosis induced by carbon tetrachloride (CCl4) in mice via regulating inflammation. MATERIAL AND METHODS The DNA was extracted from the tails of mice to identify whether the cannabinoid receptor 2 gene was successfully knocked out. A liver fibrosis model was established by an intraperitoneal injection of CCl4 into mice. Hepatic damage and hepatic fibrosis were evaluated by detecting serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and staining paraffin sections of liver tissue with hematoxylin-eosin (HE). The secretion and distribution of collagen in liver tissue were observed by Masson staining. Western blot analysis was performed to detect the expression of a-smooth muscle actin (alpha-SMA), transforming growth factor-ß1 (TGF-ß1), tumor necrosis factor alpha-induced protein 3 (A20), phosphorylated nuclear factor-kB p65 (p-NF-kappaB p65), tumor necrosis factor alpha (TNF-alpha), and interleukin-6 (IL-6) in liver tissue. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expression of IL-6 and TNF-alpha mRNA in liver tissue. RESULTS Compared with the control mice, the mice with CB2 knockout that were exposed to CCl4 exhibited increased liver damage, liver fibrosis, and upregulated alpha-SMA, TGF-ß1, A20, and p-NF-kappaB p65 protein levels. IL-6 and TNF-alpha protein levels and mRNA levels were upregulated. CONCLUSIONS The deletion of the CB2 gene promoted the activation of hepatic stellate cells in mice with liver fibrosis and aggravated liver fibrosis by up-regulating the protein expression of A20 and p-NF-kappaB p65 and inducing inflammatory response, potentially providing new insight into the treatment of liver fibrosis.

[Cannabinoid receptor 2 deletion promotes proliferation and activation of hepatic macrophages in mice with acute liver injury induced by concanavalin A].

Objective To investigate the effect of cannabinoid receptor 2 (CB2) gene deletion on liver macrophages in mice with acute liver injury induced by concanavalin A (ConA). Methods The mice with gene deletion were identified by PCR. Twenty 8-week-old wild-type C57BL/6J male mice were randomly divided into control group and model group. Twenty C57BL/6J male mice with the deletion of CB2 were divided into CB2-/- control group and CB2-/- model group. The wild-type and CB2-/- mouse model groups were injected with ConA 20 mg/kg via tail vein to replicate the model of acute liver injury, and the control groups were injected with the same amount of PBS. Nine hours after modeling, the serum was taken for the detection of alanine aminotransferase (ALT); the degree of liver injury in each group was observed by HE staining; the expression levels of CD68 and TNF-alpha proteins related to liver macrophages were detected by Western blotting; and the positive level of F4/80 in the liver tissue was detected by immunohistochemistry. Results Compared with the two control groups, the liver injury degree of mice in the model groups were serious; the serum ALT level significantly increased; the positive expression of F4/80 in the liver tissue; and the expression of CD68 and TNF-alpha proteins were significantly enhanced. Compared with the WT model group, the CB2-/- model group had an increase in the degree and area of liver injury, the serum ALT, the positive expression of F4/80 in the liver tissue, and the expression of CD68 and TNF-alpha proteins. Conclusion The deletion of CB2 gene increases the proliferation and activation of macrophages in the mice with ConA-induced acute liver injury.