Hepatic Stress Response in HCV Infection Promotes STAT3-Mediated Inhibition of HNF4A-miR-122 Feedback Loop in Liver Fibrosis and Cancer Progression

Hepatitis C virus (HCV) infection compromises the natural defense mechanisms of the liver leading to a progressive end stage disease such as cirrhosis and hepatocellular carcinoma (HCC). The hepatic stress response generated due to viral replication in the endoplasmic reticulum (ER) undergoes a stepwise transition from adaptive to pro-survival signaling to improve host cell survival and liver disease progression. The minute details of hepatic pro-survival unfolded protein response (UPR) signaling that contribute to HCC development in cirrhosis are unknown. This study shows that the UPR sensor, the protein kinase RNA-like ER kinase (PERK), mediates the pro-survival signaling through nuclear factor erythroid 2-related factor 2 (NRF2)-mediated signal transducer and activator of transcription 3 (STAT3) activation in a persistent HCV infection model of Huh-7.5 liver cells. The NRF2-mediated STAT3 activation in persistently infected HCV cell culture model resulted in the decreased expression of hepatocyte nuclear factor 4 alpha (HNF4A), a major liver-specific transcription factor. The stress-induced inhibition of HNF4A expression resulted in a significant reduction of liver-specific microRNA-122 (miR-122) transcription. It was found that the reversal of hepatic adaptive pro-survival signaling and restoration of miR-122 level was more efficient by interferon (IFN)-based antiviral treatment than direct-acting antivirals (DAAs). To test whether miR-122 levels could be utilized as a biomarker of hepatic adaptive stress response in HCV infection, serum miR-122 level was measured among healthy controls, and chronic HCV patients with or without cirrhosis. Our data show that serum miR-122 expression level remained undetectable in most of the patients with cirrhosis (stage IV fibrosis), suggesting that the pro-survival UPR signaling increases the risk of HCC through STAT3-mediated suppression of miR-122. In conclusion, our data indicate that hepatic pro-survival UPR signaling suppresses the liver-specific HNF4A and its downstream target miR-122 in cirrhosis. These results provide an explanation as to why cirrhosis is a risk factor for the development of HCC in chronic HCV infection.

Changes of Circulating Extracellular Vesicles from the Liver after Roux-en-Y Bariatric Surgery

Circulating extracellular vesicles are small particles enclosed by a phospholipid bilayer. Vesicles deriving directly from the cellular membrane by an active budding process retain cell origin specific proteins and RNA. These vesicles carry pathophysiological information from their parental cell and hold the potential to allow analysis of organs without the need for a biopsy. We included in our study 27 patients undergoing bariatric surgery. Hepatic extracellular vesicles were determined by flow cytometry. mRNA specific for hepatic cellular origin was determined in the extracellular vesicle fraction using qPCR. Surgery led to a massive reduction of weight and overall hepatic stress as determined by alanine transaminase (ALT), aspartate transaminase (AST) and γ-glutamyltransferase (GGT). Total extracellular vesicle numbers were reduced after bariatric surgery. Liver specific vesicles identified by HepPar1 or asialoglycoprotein receptor (ASGPR) were significantly reduced after bariatric surgery in both AnnexinV+ and AnnexinV− subgroups. When analyzing circulating liver-specific mRNAs, we found reduced levels of these mRNAs after surgery even though total circulating RNA remained unchanged. We conclude that circulating hepatic extracellular vesicles are detectable in samples from patients undergoing gastric bypass surgery. These vesicles are reduced after a reduction of hepatic stress also observed with classic liver enzyme measurements. We conclude that ASGPR or HepPar positive vesicles hold the potential to serve as liver specific vesicle markers.

The Effect of Benniseed Oil (Sesamum indicum Linn) on Induced Hypercholesterolemia in Albino Rats

The study was designed to investigate the antioxidant and antitoxicological potential of Sesamum indicum Linn seed (benni seed) oil on hypercholesterolemic rat. Albino rats weighing between 120-130 g were divided into two groups, group 1, was fed with normal rat diet(normal control), groups 2 was fed 1% cholesterol and 20% soya bean oil for 3 weeks to induce hypercholesterolemic state. Group 2 was later divided into groups 2, 3 and 4, group 2 was untreated, groups 3 and 4 were later fed with 5% and 10% Sesamum indicum L. seed oil incorporated in normal rat diet for another 6 weeks respectively. Significant (P<0.05) increase in lipid peroxidation (TBARs) and reduction in superoxide dismutate (SOD) and catalase (CAT) was observed in the liver of the hypercholesterolemic rats as compared to the normal control. At the same time, the oxidative stress causes significant (P<0.05) increase in serum level of Aspartate aminotransferase (AST), Alanine aminotransferase (ALT) and Alkaline phosphatase (ALP) of hypercholesterolemic rats. Administering Sesamum indicum Linn seed oil significantly reduced (P<0.05), serum ALT, AST, ALP and lipid peroxidation, elevated the level of SOD and CAT in the liver of Sesamum oil treated hypercholesterolemic rats. These findings indicate that Sesamum indicum Linn seed oil show possible prevention of hepatic stress by high cholesterol and free radical mediated oxidative stress in cells of experimental hypercholesterolemic rats.