Gut derived bacterial endotoxins, such as lipopolysaccharide (LPS), are involved in one of the important mechanisms that lead to inflammation associated with various liver diseases, including nonalcoholic fatty liver disease and alcoholic liver disease. Kahweol is a coffee-specific diterpene present in coffee bean and exhibits anti-angiogenic and anti-inflammatory activities. However, to date, the effect of kahweol on liver inflammation remains unknown. In this study, we examined whether kahweol exhibits a protective effect by inhibiting liver inflammation in primary Kupffer cells and primary hepatocytes cultures as well as their co-cultures. Kahweol decreased the LPS-induced production of interleukin 1 alpha, interleukin 1 beta, interleukin 6, and tumor necrosis factor alpha. The inhibitory effect of kahweol on the liver inflammation was associated with the down regulation of LPS-stimulated phospho-nuclear factor kappa B and -signal transducer and activator of transcription 3 expression. These results suggest that kahweol might be a novel potent agent to treat liver inflammation induced by LPS.

The SRC kinase family comprises non-receptor tyrosine kinases that are ubiquitously expressed in all cell types. Although Src is reportedly activated in pulmonary and renal fibrosis, little is known regarding its role in liver fibrosis. This study investigated whether the inhibition of Src protects against liver fibrosis. The expression of Src was upregulated in thioacetamide (TAA)-induced fibrotic mouse liver and cirrhosis of patients, and phospho-Src was upregulated during activation of hepatic stellate cells (HSC). In addition, Src inhibition reduced the expression of α-smooth muscle actin (αSMA) in primary HSCs and suppressed transforming growth factor β (TGF-β)-induced expression of connective tissue growth factor (CTGF) in hepatocytes. Src inhibitor Saracatinib also attenuated TAA-induced expression of type I collagen, αSMA, and CTGF in mouse liver tissues. The antifibrotic effect of Src inhibitors was associated with the downregulation of Smad3, but not of signal transducer and activator of transcription 3 (STAT3). In addition, Src inhibition increased autophagy flux and protected against liver fibrosis. These results suggest that Src plays an important role in liver fibrosis and that Src inhibitors could be treat liver fibrosis.

Clusterin is a glycoprotein that is expressed in most human tissues and found in body fluids. In our previous studies we demonstrated that clusterin has a protective effect against hepatic lipid accumulation and renal fibrosis; however, the role of clusterin in hepatic fibrosis is unknown. Here, we examined whether clusterin had protective effects against hepatic fibrosis using in vitro and in vivo models. Clusterin was upregulated in the livers of human cirrhotic patients and in thioacetamide (TAA)-induced and bile duct ligation mouse models of liver fibrosis. Loss and overexpression of clusterin promoted and attenuated hepatic fibrosis after TAA injection, respectively. In addition, we found that clusterin attenuates hepatic fibrosis by inhibiting the activation of hepatic stellate cells and Smad3 signaling pathways. Thus, clusterin plays an important role in hepatic fibrosis.

Chronic liver inflammation can lead to fibrosis, cirrhosis, and hepatocellular carcinoma. Kupffer cells (KC) secrete proinflammatory and fibrogenic cytokines in response to lipopolysaccharide (LPS), and so play an important role in liver inflammation, where they induce hepatocellular damage. LPS also activates hepatic stellate cells and induces extracellular matrix deposition. In this study, we used isolated primary KC, primary hepatocytes, and primary hepatic stellate cells (HSC) to investigate whether evogliptin directly inhibits inflammatory and fibrotic signaling. We found that evogliptin inhibited LPS-induced secretion of inducible nitric oxide synthase and transforming growth factor β (TGF-β) from KC. Moreover, evogliptin inhibited inflammatory mediator release from hepatocytes and hepatic stellate cell activation that were induced by KC-secreted cytokines. In hepatocytes, evogliptin also inhibited LPS-induced expression of proinflammatory cytokines and fibrotic TGF-β. In addition, evogliptin inhibited TGF-β-induced increases in connective tissue growth factor levels and HSC activation. These findings indicate that evogliptin inhibits inflammatory and fibrotic signaling in liver cells. We also showed that the inhibitory effect of evogliptin on inflammatory and fibrotic signaling is associated with the induction of autophagy.

Excessive oxidative stress plays a role in hepatotoxicity and the pathogenesis of hepatic diseases. In our previous study, the phenolic extract of beluga lentil (BLE) showed the most potent in vitro antioxidant activity among extracts of four common varieties of lentils; thus, we hypothesized that BLE might protect liver cells against oxidative stress-induced cytotoxicity. BLE was evaluated for its protective effects against oxidative stress-induced hepatotoxicity in AML12 mouse hepatocytes and BALB/c mice. H₂O₂ treatment caused a marked decrease in cell viability; however, pretreatment with BLE (25–100 μg/mL) for 24 h significantly preserved the viability of H₂O₂-treated cells up to about 50% at 100 μg/mL. As expected, BLE dramatically reduced intracellular reactive oxygen species (ROS) levels in a dose-dependent manner in H₂O₂-treated cells. Further mechanistic studies demonstrated that BLE reduced cellular ROS levels, partly by increasing expression of antioxidant genes. Furthermore, pretreatment with BLE (400 mg/kg) for 2 weeks significantly reduced serum levels of alanine transaminase and triglyceride by about 49% and 40%, respectively, and increased the expression and activity of glutathione peroxidase in CCl₄-treated BALB/c mice. These results suggest that BLE protects liver cells against oxidative stress, partly by inducing cellular antioxidant system; thus, it represents a potential source of nutraceuticals with hepatoprotective effects.

Kahweol, a coffee-specific diterpene, induces apoptosis in human cancer cells, and some targets of kahweol-mediated apoptosis have been identified. However, the specific apoptotic effects and mechanism of action of kahweol in hepatocellular carcinoma (HCC) cells are unknown. This study was performed to investigate the molecular mechanism by which kahweol induces apoptosis in HCC cells. The Src pathway is associated with apoptosis in cancer. In this study, we found that kahweol induces apoptosis by inhibiting phosphorylation of Src, and also inhibiting p-mTOR and p-STAT3. Therefore, we suggest that kahweol is a potent inhibitor of HCC cell growth.