The non-invasive serum biomarkers contributes to indicate liver fibrosis staging and evaluate the progress of chronic hepatitis B.

BACKGROUND: This study aimed to evaluate the diagnostic abilities of the non-invasive serum biomarkers to predict liver fibrosis staging and evaluate the progress of hepatitis B. METHODS: We enrolled 433 patients with chronic HBV infection had complete medical data available for the study, who underwent percutaneous liver biopsy. The extent of fibrosis was assessed using the modified METAVIR score. The predictive values of the non-invasive serum biomarkers were evaluated by the areas under the receiving operator characteristics curves (AUROCs) with 95% confidence intervals. RESULTS: The proportion of males with progressive stages of liver fibrosis was relatively larger, and the average age of patients with cirrhosis stages is older than the non-cirrhotic stages. We found PLT, GGT, ALP, TB, FIB4 and GPR to be significantly associated with liver fibrosis in our cohort. GGT showed a sensitivity of 71.4% and specificity of 76.7% in distinguishing cirrhosis (F4) from non-cirrhotic stages (F1-3), with an AUROC of 0.775 (95%CI 0.711-0.840).The AUROCs of the GPR in distinguishing cirrhosis (F4) from non-cirrhotic stages (F1-3) was 0.794 (95%CI 0.734-0.853), but it had a lower sensitivity of 59.2%. Additionally, GGT, FIB4, and GPR could differentiate advanced fibrosis (F3-4) from non-advanced fibrosis (F1-2) among individuals with chronic hepatitis B, with AUROCs of 0.723 (95%CI 0.668-0.777), 0.729 (95%CI 0.675-0.782), and 0.760 (95%CI: 0.709-0.811) respectively. CONCLUSIONS: GGT was a better biomarker to distinguish cirrhosis (F4) from non-cirrhotic stages (F1-3), while GPR was a better biomarker to identify advanced fibrosis (F3-4) and non-advanced fibrosis (F1-2) in patients with chronic hepatitis B.

NF- κ B/HDAC1/SREBP1c pathway mediates the inflammation signal in progression of hepatic steatosis.

The transcription factor nuclear factor kappa B (NF-κB) is activated in hepatocytes in the pathogenesis of hepatic steatosis. However, the action mechanism of NF-κB remains to be established in the hepatic steatosis. In this study, the P50 subunit of NF-κB was found to promote the hepatic steatosis through regulation of histone deacetylase 1 (HDAC1) in hepatocytes. The activity was supported by the phenotypes of P50 knockout (P50-KO) mice and P65 knockout (P65-KO) mice. Hepatic steatosis was reduced in the P50-KO mice, but not in the P65-KO mice. The reduction was a result of inhibition of HDAC1 activity in the P50-KO cells. Knockdown of Hdac1 gene led to suppression of hepatocyte steatosis in HepG2 cells. A decrease in sterol-regulatory element binding protein 1c (SREBP1c) protein was observed in the liver of P50-KO mice and in cell with Hdac1 knockdown. The decrease was associated with an increase in succinylation of SREBP1c protein. The study suggests that P50 stabilizes HDAC1 to support the SREBP1c activity in hepatic steatosis in the pathophysiological condition. Interruption of this novel pathway in the P50-KO, but not the P65-KO mice, may account for the difference in hepatic phenotypes in the two lines of transgenic mice.

The peripheral CB1 receptor antagonist JD5037 attenuates liver fibrosis via a CB1 receptor/ß-arrestin1/Akt pathway.

BACKGROUND AND PURPOSE: Liver fibrosis is a serious cause of morbidity and mortality worldwide and has no adequate treatment. Accumulating evidence suggests that cannabinoid CB1 receptors regulate a variety of physiological and pathological processes in the liver, and blockage of CB1 receptor signalling shows promise as a new therapy for several liver diseases. The aim of this study was to investigate the potential therapeutic effects of CB1 receptors and a peripheral CB1 receptor antagonist JD5037 in liver fibrogenesis. EXPERIMENTAL APPROACH: Liver samples from both humans and mouse models were investigated. The peripheral CB1 receptor antagonist JD5037, ß-arr1 wild type (ß-arr1-WT) and ß-arr1 knockout (ß-arr1-KO) littermate models, and primary hepatic stellate cells (HSCs) were also used. The mechanisms underlying CB1 receptor-regulated HSCs activation in fibrosis and the therapeutic potential of JD5037 were further analysed. KEY RESULTS: CB1 receptors were induced in samples from patients with liver fibrosis and from mouse models. These receptors promoted activation of HSCs in liver fibrosis via recruiting ß-arrestin1 and Akt signalling, while blockage of CB1 receptors with JD5037 attenuated CB1 receptor-regulated HSCs activation and liver fibrosis by suppressing ß-arrestin1/Akt signalling. CONCLUSIONS AND IMPLICATIONS: CB1 receptors promote the activation of HSCs and liver fibrosis via the ß-arrestin1/Akt signalling pathway. The peripheral CB1 receptor antagonist JD5037 blocked this pathway, the activation of HSCs and liver fibrosis. This compound and the associated pathway may be a novel approach to the treatment of liver fibrosis.

IL-6-driven FasL promotes NF-κBp65/PUMA-mediated apoptosis in portal hypertensive gastropathy.

Mucosal epithelial apoptosis with non-specific inflammation is an essential pathological characteristic in portal hypertensive gastropathy (PHG). However, whether a coordinated crosstalk between myeloid cells and epithelial cells involved in PHG remains unclear. IL-6, which is induced in the mucosa of PHG patients and mice, promotes FasL production via enhancing NF-κBp65 activation in myeloid cells, while blockage of IL-6 signaling by Tocilizumab or deletion of NF-κBp65 in myeloid cells attenuates the inflammatory response and Fas/FasL-mediated epithelial apoptosis in PHG. IL-6-driven FasL from myeloid cells combines with epithelial Fas receptor to encourage NF-κBp65/PUMA-mediated epithelial apoptosis in PHG, and inhibition of NF-κBp65 or knockout of PUMA alleviates Fas/FasL-mediated epithelial apoptosis in PHG. These results indicate that IL-6 drives FasL generation via NF-κBp65 in myeloid cells to promote Fas/NF-κBp65/PUMA-mediated epithelial apoptosis in PHG, and this coordinated crosstalk between myeloid cells and epithelial cells may provide a potential therapeutic target for PHG.

Induction of Posttranslational Modifications of Mitochondrial Proteins by ATP Contributes to Negative Regulation of Mitochondrial Function.

It is generally accepted that ATP regulates mitochondrial function through the AMPK signaling pathway. However, the AMPK-independent pathway remains largely unknown. In this study, we investigated ATP surplus in the negative regulation of mitochondrial function with a focus on pyruvate dehydrogenase (PDH) phosphorylation and protein acetylation. PDH phosphorylation was induced by a high fat diet in the liver of obese mice, which was associated with ATP elevation. In 1c1c7 hepatoma cells, the phosphorylation was induced by palmitate treatment through induction of ATP production. The phosphorylation was associated with a reduction in mitochondria oxygen consumption after 4 h treatment. The palmitate effect was blocked by etomoxir, which inhibited ATP production through suppression of fatty acid ß-oxidation. The PDH phosphorylation was induced by incubation of mitochondrial lysate with ATP in vitro without altering the expression of PDH kinase 2 (PDK2) and 4 (PDK4). In addition, acetylation of multiple mitochondrial proteins was induced by ATP in the same conditions. Acetyl-CoA exhibited a similar activity to ATP in induction of the phosphorylation and acetylation. These data suggest that ATP elevation may inhibit mitochondrial function through induction of the phosphorylation and acetylation of mitochondrial proteins. The results suggest an AMPK-independent mechanism for ATP regulation of mitochondrial function.

ß-Arrestin1 enhances hepatocellular carcinogenesis through inflammation-mediated Akt signalling.

G-protein-coupled receptors (GPCR) constitute the largest known superfamily for signal transduction and transmission, and they control a variety of physiological and pathological processes. GPCR adaptor ß-arrestins (ARRBs) play a role in cancerous proliferation. However, the effect of ARRBs in inflammation-mediated hepatocellular carcinogenesis is unknown. Here we show that ARRB1, but not ARRB2, is upregulated in inflammation-associated hepatocellular carcinoma (HCC) and paracancerous tissues in humans. A genotoxic carcinogen, diethylnitrosamine (DEN), significantly induces hepatic inflammation, TNF-α production and ARRB1 expression. Although ARRB1 deficiency does not affect hepatic inflammation and TNF-α production, it markedly represses hepatocellular carcinogenesis by suppressing malignant proliferation in DEN-treated mice. Furthermore, TNF-α directly induces hepatic ARRB1 expression and enhances ARRB1 interaction with Akt by binding to boost Akt phosphorylation, resulting in malignant proliferation of liver cells. Our data suggest that ARRB1 enhances hepatocellular carcinogenesis by inflammation-mediated Akt signalling and that ARRB1 may be a potential therapeutic target for HCC.

Inactivation of NF-κB p65 (RelA) in Liver Improves Insulin Sensitivity and Inhibits cAMP/PKA Pathway.

The transcription factor nuclear factor-κB (NF-κB) mediates inflammation and stress signals in cells. To test NF-κB in the control of hepatic insulin sensitivity, we inactivated NF-κB in the livers of C57BL/6 mice through deletion of the p65 gene, which was achieved by crossing floxed-p65 and Alb-cre mice to generate L-p65-knockout (KO) mice. KO mice did not exhibit any alterations in growth, reproduction, and body weight while on a chow diet. However, the mice on a high-fat diet (HFD) exhibited an improvement in systemic insulin sensitivity. Hepatic insulin sensitivity was enhanced as indicated by increased pyruvate tolerance, Akt phosphorylation, and decreased gene expression in hepatic gluconeogenesis. In the liver, a decrease in intracellular cAMP was observed with decreased CREB phosphorylation. Cyclic nucleotide phosphodiesterase-3B (PDE3B), a cAMP-degrading enzyme, was increased in mRNA and protein as a result of the absence of NF-κB activity. NF-κB was found to inhibit PDE3B transcription through three DNA-binding sites in the gene promoter in response to tumor necrosis factor-α. Body composition, food intake, energy expenditure, and systemic and hepatic inflammation were not significantly altered in KO mice on HFD. These data suggest that NF-κB inhibits hepatic insulin sensitivity by upregulating cAMP through suppression of PDE3B gene transcription.

Regulation of insulin degrading enzyme activity by obesity-associated factors and pioglitazone in liver of diet-induced obese mice.

Insulin degrading enzyme (IDE) is a potential drug target in the treatment of type 2 diabetes (T2D). IDE controls circulating insulin through a degradation-dependent clearance mechanism in multiple tissues. However, there is not sufficient information about IDE regulation in obesity. In this study, we test obesity-associated factors and pioglitazone in the regulation of IDE in diet-induced obese (DIO) C57BL/6 mice. The enzyme activity and protein level of IDE were increased in the liver of DIO mice. Pioglitazone (10 mg/kg/day) administration for 2 months significantly enhanced the enzyme activity (75%), protein (180%) and mRNA (100%) of IDE in DIO mice. The pioglitazone-induced changes were coupled with 50% reduction in fasting insulin and 20% reduction in fasting blood glucose. The mechanism of IDE regulation in liver was investigated in the mouse hepatoma cell line (Hepa 1c1c7 cells), in which pioglitazone (5 µM) increased IDE protein and mRNA in a time-dependent manner in an 8 h study. Free fatty acid (palmitate 300 µM) induced IDE protein, but reduced the mRNA. Glucagon induced, and TNF-α decreased IDE protein. Insulin did not exhibit any activity in the same condition. In summary, pioglitazone, FFA and glucagon directly increased, but TNF-α decreased the IDE activity in hepatocytes. The results suggest that IDE activity is regulated in liver by multiple factors in obesity and pioglitazone may induce IDE activity in the control of T2D.