Infection and autoimmune liver diseases

Abstract

Autoimmune liver diseases (AiLD) comprise a heterogeneous group of disorders inflicting damage to the liver. Those diseases are characterized by an immune-mediated destruction of the hepatocytes (autoimmune hepatitis, AIH) or the biliary epithelial cells [primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC)]. At times, overlapping features of AIH and PBC or AIH and PSC are noted in an insignificant number of affected patients. The pathogenesis and pathophysiological mechanisms responsible for the initial induction and subsequent progression of liver impairment are largely undefined but genetic, epigenetic, immunological, and environmental factors appear to be essential. Among various environmental triggers, infectious triggers have been incriminated largely with the development of PBC and AIH and to a lesser extent with PSC. The link between pathogens and PSC remains less defined, though the input of microbiome alterations has been considered imperative. The most common mechanism connecting infectious agents of any kind, whether microbes, viruses, or parasites, with AiLD is based on the assumption that molecular mimicry and immunological cross-reactivity involving exogenous and self-mimicking antigenic targets are heavily operated linking to liver autoimmunity in the form of auto-antibodies and indeed overt clinical disease, which can lead to hepatic failure. This chapter will underline the existing data on the involvement of infectious agents, which have been investigated in PBC and AIH.