The role of long noncoding RNAs (lncRNAs) in viral infection is poorly studied. We have identified hepatitis C virus (HCV)-Stimulated lncRNAs (CSRs) by transcriptome analysis. Interestingly, two of these CSRs (PVT1 and UCA1) play relevant roles in tumorigenesis, providing a novel link between HCV infection and development of liver tumors. Expression of some CSRs seems induced directly by HCV, while others are upregulated by the antiviral response against the virus. In fact, activation of pathogen sensors induces the expression of CSR32/EGOT. RIG-I and the RNA-activated kinase PKR sense HCV RNA, activate NF-jB and upregulate EGOT. EGOT is increased in the liver of patients infected with HCV and after infection with influenza or Semliki Forest virus (SFV). Genome-wide guilt-by-association studies predict that EGOT may function as a negative regulator of the antiviral pathway. Accordingly, EGOT depletion increases the expression of several interferon-stimulated genes and leads to decreased replication of HCV and SFV. Our results suggest that EGOT is a lncRNA induced after infection that increases viral replication by antagonizing the antiviral response.

Liver cirrhosis results from chronic hepatic damage and is characterized by derangement of the organ architecture with increased liver fibrogenesis and defective hepatocellular function. It frequently evolves into progressive hepatic insufficiency associated with high mortality unless liver transplantation is performed. We have hypothesized that the deficiency of critical nutrients such as essential omega-3 fatty acids might play a role in the progression of liver cirrhosis. Here we evaluated by LC-MS/MS the liver content of omega-3 docosahexaenoic fatty acid (DHA) in cirrhotic patients and investigated the effect of DHA in a murine model of liver injury and in the response of hepatic stellate cells (HSCs) (the main producers of collagen in the liver) to pro-fibrogenic stimuli. We found that cirrhotic livers exhibit a marked depletion of DHA and that this alteration correlates with the progression of the disease. Administration of DHA exerts potent anti-fibrogenic effects in an acute model of liver damage. Studies with HSCs show that DHA inhibits fibrogenesis more intensely than other omega-3 fatty acids. Data from expression arrays revealed that DHA blocks TGFβ and NF-κB pathways. Mechanistically, DHA decreases late, but not early, SMAD3 nuclear accumulation and inhibits p65/RelA-S536 phosphorylation, which is required for HSC survival. Notably, DHA increases ADRP expression, leading to the formation of typical quiescence-associated perinuclear lipid droplets. In conclusion, a marked depletion of DHA is present in the liver of patients with advanced cirrhosis. DHA displays anti-fibrogenic activities on HSCs targeting NF-κB and TGFβ pathways and inducing ADPR expression and quiescence in these cells.

In liver cirrhosis, abnormal liver architecture impairs efficient transduction of hepatocytes with large viral vectors such as adenoviruses. Here we evaluated the ability of adeno-associated virus (AAV) vectors, small viral vectors, to transduce normal and cirrhotic rat livers. Using AAV serotype-1 (AAV1) encoding luciferase (AAV1Luc) we analyzed luciferase expression with a CCD camera. AAV1Luc was injected through the hepatic artery (intra-arterial (IA)), the portal vein (intra-portal (IP)), directly into the liver (intra-hepatic (IH)) or infused into the biliary tree (intra-biliar). We found that AAV1Luc allows long-term and constant luciferase expression in rat livers. Interestingly, IP administration leads to higher expression levels in healthy than in cirrhotic livers, whereas the opposite occurs when using IA injection. IH administration leads to similar transgene expression in cirrhotic and healthy rats, whereas intra-biliar infusion is the least effective route. After 70% partial hepatectomy, luciferase expression decreased in the regenerating liver, suggesting lack of efficient integration of AAV1 DNA into the host genome. AAV1Luc transduced mainly the liver but also the testes and spleen. Within the liver, transgene expression was found mainly in hepatocytes. Using a liver-specific promoter, transgene expression was detected in hepatocytes but not in other organs. Our results indicate that AAVs are convenient vectors for the treatment of liver cirrhosis.

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