Cytokines - their pathogenic and therapeutic role in chronic viral hepatitis.

Cytokines make up a network of molecules involved in the regulation of immune response and organ functional homeostasis. Cytokines coordinate both physiological and pathological processes occurring in the liver during viral infection, including infection control, inflammation, regeneration, and fibrosis. Hepatitis B and hepatitis C viruses interfere with the complex cytokine network brought about by the immune system and liver cells in order to prevent an effective immune response, capable of viral control. This situation leads to intrahepatic sequestration of nonspecific inflammatory infiltrates that release proinflammatory cytokines, which in turn favor chronic inflammation and fibrosis. The therapeutical administration of cytokines such as interferon alpha may result in viral clearance during persistent infection, and revert this process.