Current status and perspectives of the clinical and basic research on concomitant chronic hepatitis B virus infection and nonalcoholic fatty liver disease

Chronic hepatitis B virus infection (CBI) and nonalcoholic fatty liver disease (NAFLD) are the two main etiologies of chronic liver diseases worldwide, and therefore, concomitant CBI and NAFLD (Co-CBI&NAFLD) is relatively common. There are still controversies over the influence of the interaction between CBI and NAFLD, especially NAFLD, on the progression, antiviral response, and outcome of chronic hepatitis B (CHB). Current clinical and basic research on Co-CBI&NAFLD have shown that NAFLD could inhibit HBV DNA replication to a certain degree, manifesting as a relatively low HBV DNA load, and it might increase HBsAg clearance rate in patients with CHB. Prospective or retrospective cohort studies have shown that patients with Co-CBI&NAFLD tend to have more rapid progression of liver fibrosis than those with CHB alone, as well as increased incidence rates of liver cirrhosis and hepatocellular carcinoma. Histologically, Co-CBI&NAFLD has the pathological changes of both CHB and NAFLD, and therefore, it is difficult to identify their own characteristic lesions. At present, the natural history and pathogenesis of Co-CBI&NAFLD remain unclear, and its pathological characteristics have not been fully identified. There is still a lack of high-level evidence-based supporting information on the influence of NAFLD on the course of CHB, especially its impact on antiviral response and disease outcome, and there are also no guidelines for the diagnosis/treatment or management of Co-CBI&NAFLD in China and globally. Solutions to the above issues will definitely deepen the understanding of Co-CBI&NAFLD, standardize and improve clinical diagnosis/treatment or management, and thus reduce the incidence and mortality rates of related end-stage liver diseases.148