Assessment of the possible roles of SB-269970 versus ketanserin on carbon tetrachloride-induced liver fibrosis in rats: Oxidative stress/TGF-β1-induced HSCs activation pathway

The janus face of serotonin: Regenerative promoter and chronic liver disease aggravator

The progression of liver diseases, from viral hepatitis and fatty liver disease to cirrhosis and hepatocellular carcinoma (HCC), is the most representative series of pathological events in liver diseases. While serotonin (5-HT) primarily regulates brain functions such as psychology, mood, and appetite in the central nervous system (CNS), peripheral 5-HT plays a crucial role in regulating tumor development, glucose and lipid metabolism, immune function and inflammatory response related to liver diseases. These peripheral physiological processes involving 5-HT are the key mechanisms driving the development of these liver diseases. This study presents an overview of the existing literature, focusing on the role of 5-HT in HCC, cirrhosis, fatty liver disease, viral hepatitis, and liver injury. In summary, while 5-HT promotes liver regeneration, it can also contribute to the progression of chronic liver disease. These findings indicate the potential for the development and use of 5-HT-related drugs for the treatment of liver diseases, including HCC and cirrhosis.

Oxymatrine alleviates high-fat diet/streptozotocin-induced non-alcoholic fatty liver disease in C57BL/6 J mice by modulating oxidative stress, inflammation and fibrosis

Non-alcoholic fatty liver disease (NAFLD) represents a complex complication of type 2 diabetes mellitus (T2DM). Oxymatrine (OMT) is an alkaloid extracted from Sophora flavescens with broad pharmacological effects. However, there is currently a lack of research on OMT in the field of NAFLD. The present study aimed to explore the effects and underlying mechanisms of oxymatrine in treating T2DM with NAFLD. The T2DM mice model was induced by high-fat diet (HFD) combined with streptozotocin (STZ) injection in male C57BL/6 J mice. Animals were randomly divided into four groups (n = 8): Control group, DC group, OMT-L group (45 mg/kg i.g.), and OMT-H group (90 mg/kg, i.g.). The drug was administered once a day for 8 weeks. In addition, HepG2 hepatocytes were incubated with palmitic acid (PA) to establish a fatty liver cell model. Treated with OMT, the body weight and fasting blood glucose (FBG) of DC mice were reduced and the liver organ coefficient was significantly optimized. Meanwhile, OMT markedly enhanced the activities of key antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), and also reduced malondialdehyde (MDA) levels. These biochemical alterations were accompanied by noticeable improvements in liver histopathology. Furthermore, OMT down-regulated the expression of NOD-like receptor protein 3 (NLRP3), interleukin-1β (IL-1β), transforming growth factor-β1 (TGF-β1) and collagen I significantly, highlighting its potential in modulating inflammatory and fibrotic pathways. In conclusion, OMT improved liver impairment effectively in diabetic mice by suppressing oxidative stress, inflammation and fibrosis. These results suggest that OMT may represent a novel therapy for NAFLD with diabetes.

Mechanisms of 5-HT receptor antagonists in the regulation of fibrosis in a 3D human liver spheroid model

Non-alcoholic steatohepatitis (NASH) is a major health problem leading to liver fibrosis and hepatocellular carcinoma, among other diseases, and for which there is still no approved drug treatment. Previous studies in animal models and in LX-2 cells have indicated a role for serotonin (5-HT) and 5-HT receptors in stellate cell activation and the development of NASH. In the current study, we investigated the extent to which these findings are applicable to a human NASH in vitro model consisting of human liver spheroids containing hepatocytes and non-parenchymal cells. Treatment of the spheroids with 5-HT or free fatty acids (FFA) induced fibrosis, whereas treatment of the spheroids with the 5-HT receptor antagonists ketanserin, pimavanserin, sarpogrelate, and SB269970 inhibited FFA-induced fibrosis via a reduction in stellate cell activation as determined by the expression of vimentin, TGF-β1 and COL1A1 production. siRNA-based silencing of 5-HT2A receptor expression reduced the anti-fibrotic properties of ketanserin, suggesting a role for 5-HT receptors in general and 5-HT2A receptors in particular in the FFA-mediated increase in fibrosis in the human liver spheroid model. The results suggest a contribution of the 5-HT receptors in the development of FFA-induced human liver fibrosis with implications for further efforts in drug development.

Citrus limon (L.) Osbeck Fruit Peel Extract Attenuates Carbon Tetrachloride-Induced Hepatocarcinogenesis in Sprague-Dawley Rats

Background

Traditional herbal medicine practitioners in the Ashanti region of Ghana use the fruit peels of Citrus limon (L.) Osbeck (C. limon) in preventive and curative treatment of many cancers including liver cancer. This ethnobotanical claim remains to be verified scientifically. Aim of the Study. This study investigated prophylactic hepatoprotective and anti-HCC effects of C. limon peel extract (LPE) in CCl4/olive oil-induced HCC-like rats.

Materials and Methods

After preparation of LPE, it was subjected to phytochemical screening using standard phytochemical methods. A total of 30 healthy adult male Sprague-Dawley rats (weighing 150-200 g) were randomly assigned into six groups of 5 rats each. Rats in the control group received olive oil (5 mL/kg ip) twice weekly for 16 weeks. Rats in the model group received CCl4/olive oil (2 mL/kg, ip) twice weekly for 16 weeks. Rats in capecitabine (10 mg/kg po) and LPE (50, 100, and 200 mg/kg po) groups received CCl4/olive oil (2 mL/kg, i.p) in the morning and their respective treatments in the afternoon twice a week for 16 weeks. Rats in all groups had free access to food and water ad libitum. Body weight and survival rates were monitored. Rats were sacrificed under deep anesthesia, blood was collected, and liver and other organs were isolated. Aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), gamma-glutamyltransferase (GGT), prothrombin time, bilirubin, C-reactive protein (CRP), alpha- (α-) fetoprotein (AFP), and liver histology were assessed.

Results

Alkaloids, tannins, flavonoids, terpenoids, and saponins were detected in LPE. Model rats demonstrated increased serum levels of AFP, CRP, ALP, GGT, ALT, and AST, prothrombin time, total bilirubin, direct bilirubin, blood lymphocyte, and monocyte counts, but decreased serum albumin and total protein compared to control rats. Unlike the control, model rats demonstrated fat accumulation in periportal and centrilobular hepatocytes and neoplastic transformation. Semiquantitation of periodic acid Schiff- (PAS-) stained liver sections showed decreased glycogen storage in hepatocytes of model rats compared to control rats. Compared to the model, LPE treatment protected against CCl4-induced hepatocarcinogenesis, which was evidenced by decreased AFP, CRP, liver enzymes, total and direct bilirubin, prothrombin time, and blood lymphocyte and monocyte counts; attenuation of fat accumulation; and increased glycogen storage, albumin, and total protein.

Conclusion

LPE abates CCl4-induced hepatocarcinogenesis by attenuating liver inflammation and improving metabolic, biosynthetic, and detoxification functions of the liver. The prophylactic hepatoprotective and anti-hepatocarcinogenic effects of LPE are attributable to its phytochemical composition raising hopes of finding potential anticancer bioactive compounds from C. limon fruit peels.

Protective effects of epigallocatechin-3-o-gallate combined with organic selenium against transforming growth factor-beta 1-induced fibrosis in LX-2 cells

In this study, we investigated the protective effects and possible mechanism of epigallocatechin-3-o-gallate (EGCG) combined with organic selenium in transforming growth factor (TGF)-β1-activated LX-2 cells. After 12 h of starvation, LX-2 cells were treated with 10 ng/ml of recombinant TGF-β1 and different concentrations of EGCG, L-selenomethionine (L-SeMet), or L-selenomethylcysteine (L-SeMC) for 24 h. We found that 100 and 200 μM EGCG combined with 1 mM L-SeMet or L-SeMC showed a synergistic effect in decreasing the survival rate of activated LX-2 cells. In addition, the combination of 100 mM EGCG and 1 mM L-SeMet or L-SeMC promoted the apoptosis of activated LX-2 cells. Compared with the EGCG treatment group, the combination intervention group had significantly suppressed levels of hepatic stellate cell activation markers including alpha-smooth muscle actin, collagen type I alpha 1, collagen type III alpha 1, 5-hydroxytryptophan (5-HT), and 5-HT receptors 2A and 2B. Moreover, interleukin-10 levels were decreased, while TGF-β1 levels were increased after TGF-β1 activation in LX-2 culture medium, whereas the combin1ation intervention reversed this phenomenon. The combination treatment had a more pronounced effect than any single treatment at the same dose. These results demonstrated that the combination of EGCG and organic selenium synergistically improves the TGF-β1-induced fibrosis of LX-2 cells to some extent by promoting apoptosis and inhibiting cell activation. PRACTICAL APPLICATIONS: Here, we found that the effects of epigallocatechin-3-o-gallate (EGCG) + L-selenomethionine or L-selenomethylcysteine were more pronounced than those of EGCG alone. Future studies should investigate the protective effects of green tea and selenium-enriched green tea against hepatic fibrosis and explore the differences in their molecular mechanisms. The results of this study will be helpful for the development and utilization of selenium-enriched tea for food processing and health supplement production.

[1-deoxynojirimycin alleviates liver fibrosis induced by type 2 diabetes in mice]

OBJECTIVE

To investigate the effect of 1-deoxynojirimycin (DNJ) for improving diabetic liver fibrosis and explore the underlying mechanism.

METHODS

Mouse models of type 2 diabetes were established in 10 Kunming mice by high-fat diet feeding for 8 weeks and intraperitoneal injection of STZ, with 5 mice receiving intraperitoneal injection of citrate buffer solution with normal feeding as the control group. The mouse models were randomized into two groups (n=5) for further highfat feeding (model group) and additional treatment with 10% DNJ in drinking water (200 mg · kg^-1 per day; DNJ group) for 8 weeks. The mice were monitored for changes in body weight (BW), blood glucose, serum total cholesterol (TC), triglyceride (TG) and superoxide dismutase (SOD) levels. The pathological changes in the liver tissue were observed using HE and Sirius Red staining, and the solubility of collagens in the liver tissues was determined. The expression levels of MCP-1, TNF-α, IL-1β and TGF-β1 mRNA were detected with real-time PCR, and the protein expressions of α-SMA and collagen2 (ColA2) were determined with Western blotting. In the in vitro experiment, mouse fibroblasts L929 cells were pretreated with DNJ (10 μg/ mL) or PBS for 30 min followed by culture in high-glucose medium for 24 h, and the level of ROS production was measured using dihydroethidium (DHE) staining.

RESULTS

In the mouse model of type 2 diabetes, DNJ treatment significantly lowered serum level of glucose, TC, and TG (P < 0.05) and increased serum SOD activity (P < 0.05). DNJ obviously attenuated liver fibrosis in the diabetic mice, as shown by alleviated cross-linking of collagens and reduced contents of pepsin-solubilized collagen (PSC) and total collagen (P < 0.05). DNJ treatment also significantly reduced the overexpression of the proinflammatory cytokines and fibrosis-related cytokines induced by diabetes (P < 0.05). In L929 cells exposed to high glucose, pretreatment with DNJ significantly lowered the intensity of red fluorescence in DHE staining.

CONCLUSION

DNJ can attenuate type 2 diabetes-induced liver fibrosis in mice through its hypoglycemic, anti-inflammatory and anti-oxidative effects.

Modulation of serotonin in the gut-liver neural axis ameliorates the fatty and fibrotic changes in non-alcoholic fatty liver

The etiology of non-alcoholic fatty liver disease (NAFLD) consists of various factors, including neural signal pathways. However, the molecular mechanisms of the autonomic neural signals influencing NAFLD progression have not been elucidated. Therefore, we examined the involvement of the gut-liver neural axis in NAFLD development and tested the therapeutic effect of modulation of this axis in this study. To test the contribution of the gut-liver neural axis, we examined NAFLD progression with respect to body weight, hepatic steatosis, fibrosis, intestinal tight junction, microbiota and short-chain fatty acids in NAFLD models of choline-deficient defined L-amino-acid and high-fat diet-fed mice with or without blockades of autonomic nerves from the liver. Blockade of the neural signal from the liver to the gut in these NAFLD mice models ameliorated the progression of liver weight, hepatic steatosis and fibrosis by modulating serotonin expression in the small intestine. It was related to the severity of the liver pathology, the tight junction protein expression, microbiota diversity and short-chain fatty acids. These effects were reproduced by administrating serotonin antagonist, which ameliorated the NAFLD progression in the NAFLD mice models. Our study demonstrated that the gut-liver neural axis is involved in the etiologies of NAFLD progression and that serotonin expression through this signaling network is the key factor of this axis. Therefore, modulation of the gut-liver neural axis and serotonin antagonist ameliorates fatty and fibrotic changes in non-alcoholic fatty liver, and can be a potential therapeutic target of NAFLD.This article has an associated First Person interview with the first author of the paper.

Withaferin A Exerts Preventive Effect on Liver Fibrosis through Oxidative Stress Inhibition in a Sirtuin 3-Dependent Manner

Sirtuin 3 (SIRT3) is a deacetylase involved in the development of many inflammation-related diseases including liver fibrosis. Withaferin A (WFA) is a bioactive constituent derived from the Withania somnifera plant, which has extensive pharmacological activities; however, little is known about the regulatory role of SIRT3 in the WFA-induced antifibrogenic effect. The current study is aimed at investigating the role of SIRT3 in WFA-induced antioxidant effects in liver fibrosis. Our study verified that WFA attenuated platelet-derived growth factor BB- (PDGF-BB-) induced liver fibrosis and promoted PDGF-BB-induced SIRT3 activity and expression in JS1 cells. SIRT3 silencing attenuated the antifibrogenic and antioxidant effects of WFA in activated JS1 cells. Moreover, WFA inhibited carbon tetrachloride- (CCl₄-) induced liver injury, collagen deposition, and fibrosis; increased the SIRT3 expression; and suppressed the CCl₄-induced oxidative stress in fibrotic livers of C57/BL6 mice. Furthermore, the antifibrogenic and antioxidant effects of WFA could be available in CCl₄-induced WT (129S1/SvImJ) mice but were unavailable in CCl₄-induced SIRT3 knockout (KO) mice. Our study suggested that WFA inhibited liver fibrosis through the inhibition of oxidative stress in a SIRT3-dependent manner. WFA could be a potential compound for the treatment of liver fibrosis.

Methyl ferulic acid attenuates liver fibrosis and hepatic stellate cell activation through the TGF-β1/Smad and NOX4/ROS pathways

Liver fibrosis is a pathological wound-healing response caused by chronic liver damage due to a virus, autoimmune disorder, or drugs. Hepatic stellate cells (HSCs) play an essential role in the pathogenesis of liver fibrosis. Methyl ferulic acid (MFA), a biologically active monomer, has a protective effect on liver injury. However, the effects and roles of MFA in liver fibrosis remain unknown. The purpose of the current study was to investigate the effect of MFA on hepatic fibrosis and the underlying mechanisms. Human hepatic stellate LX-2 cells were exposed to 5 μg/L TGF-β1 for 48 h to stimulate liver fibrosis in vitro. Using MTT, RT-PCR and Western blot analysis, we revealed that MFA significantly inhibited the proliferation of LX-2 cells as well as decreased the expressions of α-SMA and type I collagen in LX-2 cells. SD rats were fed with ethanol, and this combined with the intraperitoneal injection of CCl₄ induced liver fibrosis in vivo. We found that the administration of MFA markedly decreased the levels of hyaluronic acid (HA), procollagen type III (PC-III), type IV collagen (CIV) and laminin (LN) in the serum, inhibited the expression of α-smooth muscle actin (α-SMA) as well as type I and type III collagen, and up-regulated the ratio of MMP-2/TIMP-1 in rats. The antifibrotic effects of MFA were also evaluated by H&E staining and Masson's trichrome staining. In addition, further studies suggested that this protection by MFA from liver fibrosis was possibly related to the inhibition of TGF-β1/Smad and NOX4/ROS signalling. In conclusion, our results demonstrate that MFA attenuated liver fibrosis and hepatic stellate cell activation by inhibiting the TGF-β1/Smad and NOX4/ROS signalling pathways.