Biopsy-confirmed liver fibrosis is a prognostic factor for patients with nonalcoholic fatty liver disease (NAFLD). We performed a systematic review to quantify the prognostic value of fibrosis stage in patients with NAFLD and the subgroup of patients with nonalcoholic steatohepatitis (NASH) and to assess the evidence that change in fibrosis stage is a surrogate endpoint. We searched the MEDLINE, Embase, Cochrane Library, and trial registry databases through August 2018 for prospective or retrospective cohort studies of liver-related clinical events and outcomes in adults with NAFLD or NASH. We collected data on mortality (all cause and liver related) and morbidity (cirrhosis, liver cancer, and all liver-related events) by stage of fibrosis, determined by biopsy, for patients with NAFLD or NASH. Using fibrosis stage 0 as a reference population, we calculated fibrosis stage-specific relative risk (RR) and 95% confidence interval (CI) values for mortality and morbidities. We performed fixed-effect and random-effect model meta-analyses. Metaregression was used to examine associations among study design (prospective vs retrospective cohort), overall risk of bias (medium or high), and mean duration of follow-up (in years). Our meta-analysis included 13 studies, comprising 4428 patients with NAFLD; 2875 of these were reported to have NASH. Compared with no fibrosis (stage 0), unadjusted risk increased with increasing stage of fibrosis (stage 0 vs 4): all-cause mortality RR, 3.42 (95% CI, 2.63-4.46); liver-related mortality RR, 11.13 (95% CI, 4.15-29.84); liver transplant RR, 5.42 (95% CI, 1.05-27.89); and liver-related events RR, 12.78 (95% CI, 6.85-23.85). The magnitude of RR did not differ significantly after adjustment for confounders, including age or sex in the subgroup of NAFLD patients with NASH. Three studies examined the effects of increasing fibrosis on quality of life had inconsistent findings. In a systematic review and meta-analysis, we found biopsy-confirmed fibrosis to be associated with risk of mortality and liver-related morbidity in patients with NAFLD, with and without adjustment for confounding factors and in patients with reported NASH. Further studies are needed to assess the association between fibrosis stage and patient quality of life and establish that change in liver fibrosis stage is a valid endpoint for use in clinical trials.

Chronic hepatitis B virus (HBV) infection is prevalent, deadly and seldom cured due to the persistence of viral episomal DNA (cccDNA) in infected cells. Newly developed genome engineering tools may offer the ability to directly cleave viral DNA, thereby promoting viral clearance. Here, we show that the CRISPR/Cas9 system can specifically target and cleave conserved regions in the HBV genome, resulting in robust suppression of viral gene expression and replication. Upon sustained expression of Cas9 and appropriately chosen guide RNAs, we demonstrate cleavage of cccDNA by Cas9 and a dramatic reduction in both cccDNA and other parameters of viral gene expression and replication. Thus, we show that directly targeting viral episomal DNA is a novel therapeutic approach to control the virus and possibly cure patients.

Significance: Major obstacles for using human hepatocytes to study hepatitis B virus (HBV) pathobiology are rapid loss of hepatocyte function after plating and the variability between hepatocyte donors. We show that micropatterning and coculturing of primary human hepatocytes with fibroblasts (MPCC format) maintains prolonged infection that is restricted by the innate immune response, and can be further boosted by suppression of this response. To address the problem of donor variability, we show that induced pluripotent stem cells (iPSC) differentiated into hepatocyte-like cells support HBV infection in a differentiation-dependent manner. Our study opens an avenue for using these systems to study virus–host interactions and test antiviral drugs, and suggests HBV permissiveness as a surrogate reporter to assess the degree of differentiation of candidate iPSC-derived hepatocyte-like cells.

RNA interference (RNAi) is the process of sequence–specific gene silencing, initiated by double–stranded RNA (dsRNA) that is homologous in sequence to the target gene. Because it has been shown that RNAi can be accomplished in cultured mammalian cells by introducing small interfering RNAs (siRNAs), much effort has been invested in exploiting this phenomenon for experimental and therapeutic means. In this study, we present a series of experiments showing a significant reduction in hepatitis B virus (HBV) transcripts and proteins in cell culture, as well as in the viral replicative forms, induced by siRNA–producing vectors. The antiviral effect is sequence–specific and does not depend on active viral replication. In conclusion, our data suggest that RNAi may provide a powerful therapeutic tool, acting both on replication–competent and on replication–incompetent HBV. (Hepatology 2003;37:764–770.)