Tumor necrosis factor α stimulates endothelin-1 synthesis in rat hepatic stellate cells in hepatic wound healing through a novel IKK/JNK pathway

Yang²,

International Journal of Molecular Medicine

et al. 2012

Non-alcoholic steatohepatitis (NASH) is characterized by hepatocellular injury and initial fibrosis severity has been suggested as an important prognostic factor of NASH. Silymarin was reported to improve carbon tetrachloride-induced liver fibrosis and reduce the activation of hepatic stellate cells (HSC). We investigated whether silymarin could suppress the activation of HSCs in NASH induced by methionine- and choline-deficient (MCD) diet fed to insulin-resistant rats. NASH was induced by feeding MCD diet to obese diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Non-diabetic Long-Evans Tokushima Otsuka (LETO) rats were fed with standard chow and served as the control. OLETF rats were fed on either standard laboratory chow, or MCD diet or MCD diet mixed with silymarin. Histological analysis of the liver showed improved non-alcoholic fatty liver disease (NAFLD) activity score in silymarin-fed MCD-induced NASH. Silymarin reduced the activation of HSCs, evaluated by counting α-smooth muscle actin (SMA)-positive cells and measuring α-SMA mRNA expression in the liver lysates as well as in HSCs isolated from the experimental animals. Although silymarin decreased α1-procollagen mRNA expression in isolated HSCs, the anti-fibrogenic effect of silymarin was not prominent so as to show significant difference under histological analysis. Silymarin increased the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and decreased tumor necrosis factor (TNF)-α mRNA expression in the liver. Our study suggested that the possible protective effect of silymarin in diet induced NASH by suppressing the activation of HSCs and disturbing the role of the inflammatory cytokine TNF-α.

Section: Discussionmentioning

confidence: 58%

Silymarin suppresses hepatic stellate cell activation in a dietary rat model of non-alcoholic steatohepatitis: Analysis of isolated hepatic stellate cells

Yang²,

International Journal of Molecular Medicine

et al. 2012

“…Under normal conditions, the sinusoidal endothelium is the major source of EDN1, which appears to be important in intrahepatic circulatory homeostasis. However, during stimulation by a number of exogenous factors such as TGFβ17, EDN1 synthesis shifts to not only induce stellate cell proliferation but also increases ECM production18 by virtue of the expression of EDNRA and EDNRB19. EDN1 exhibits an autocrine effect on HSCs and is involved in both HSC activation and the contractile response of HSCs to destroy the graft sinusoidal microcirculation balance20.…”

Section: Discussionmentioning

confidence: 99%

Eggshell membrane ameliorates hepatic fibrogenesis in human C3A cells and rats through changes in PPARγ-Endothelin 1 signaling

Jia

Saito

et al. 2014

Sci Rep

Our previous nutrigenomic findings indicate that eggshell membrane (ESM) may prevent liver fibrosis. Here we investigated the effects and mechanisms underlying ESM intervention against liver injury by using DNA microarray analysis and comparative proteomics. In vitro hydrolyzed ESM attenuated the TGFβ1-induced procollagen production of human hepatocyte C3A cells and inhibited the expression of Endothelin 1 (EDN1) and its two receptors, and extracellular matrix components. In vivo male Wistar rats were allocated into a normal control group, a CCl4 group (hypodermic injection of 50% CCl4 2×/wk) and an ESM group (20 g ESM/kg diet with CCl4 injection) for 7 wks. Dietary ESM ameliorated the elevated activity of ALT/AST, oxidative stress and collagen accumulation in liver, accompanied by the down-regulated expression of Edn1 signaling and notable profibrogenic genes and growth factors as well as peroxisome proliferator-activated receptor gamma (PPARγ). Concomitantly, the decreased expressions of Galectin-1 and Desmin protein in the ESM group indicated the deactivation of hepatic stellate cells (HSCs). Through a multifaceted integrated omics approach, we have demonstrated that ESM can exert an antifibrotic effect by suppressing oxidative stress and promoting collagen degradation by inhibiting HSCs' transformation, potentially via a novel modulation of the PPARγ-Endothelin 1 interaction signaling pathway.

“…Endothelin promotes HSC activation in an autocrine manner. TNF also induces endothlin-1 production through JNK 96 .…”

Section: Hsc Activation and Fibrosismentioning

confidence: 99%

A Liver Full of JNK: Signaling in Regulation of Cell Function and Disease Pathogenesis, and Clinical Approaches

2012

c-Jun-N-terminal Kinase (JNK) is a mitogen-activated protein kinase (MAPK) family member that is activated by diverse stimuli, including cytokines (such as tumor necrosis factor and interleukin-1), reactive oxygen species (ROS), pathogens, toxins, drugs, endoplasmic reticulum stress, free fatty acids, and metabolic changes. Upon activation, JNK induces multiple biologic events through the transcription factor AP-1 and transcription-independent control of effector molecules. JNK isozymes regulate cell death and survival, differentiation, proliferation, ROS accumulation, metabolism, insulin signaling, and carcinogenesis in the liver. The biologic functions of JNK are isoform, cell-type, and context dependent. Recent studies using genetically engineered mice showed that loss or hyper-activation of the JNK pathway contributes to the development of inflammation, fibrosis, cancer growth, and metabolic diseases that include obesity, hepatic steatosis, and insulin resistance. We review the functions and pathways of JNK in liver physiology and pathology, and discuss findings from pre-clinical studies with JNK inhibitors.