[New aspects of the development of liver diseases – with special regard to the role of autophagy and microRNA].

Autophagy plays an important role in the homeostasis of the cells and it may be upregulated in response to several types of stresses. Deregulation of autophagy is a key mechanism in the pathogenesis and progression of several liver diseases. Deficient autophagy can contribute to liver steatosis, to endoplasmic reticulum stress and to the progression of non-alcoholic fatty liver disease. Chronic alcohol consumption inhibits autophagy. The accumulated mutant protein in the endoplasmic reticulum can be degraded by autophagy in alpha-1-antitrypsin deficiency. Hepatitis C and B viruses may exploit the autophagy pathway to promote the own replication. Hepatitis C virus non-structural protein 5A and 5B have roles in the induction of autophagosomes. MicroRNAs regulate multiple physiological, pathological functions and autophagy through the modulation of gene expression. MicroRNA-122 is involved in HCV replication. In HBV-infected livers, the microRNA pathways related to cell death, DNA damage, recombination and signal transduction were activated. MicroRNA-122 effects multiple important factors which regulate the lipid and carbohydrate metabolisms in human non-alcoholic fatty liver disease. Oxidative stress and free oxygen radicals generation involved in alcoholic liver diseases development are regulated by microRNAs through different pathways. MicroRNAs control autophagy process and autophagy regulates the expression of microRNA-s. The exploration of their interactions contributes to understanding the development of liver diseases. Orv Hetil. 2020; 161(35): 1499-1455.