Liver fibrosis mechanisms – the role of stellate cells, oxidative and nitrosative stress

Abstract

Liver fibrosis is a chronic and complex pathological process, occuring in patients with chronic liver diseases. The most common cause of liver fibrosis is the alcoholic liver disease, viral hepatitis type B, C and D, as well as autoimmune diseases. Other causes include metabolic dysfunctions like hemachromatosis and Wilson’s disease, biliary duct disorders, damaging effects of medicine and parasite infections. Fibrosis’ dynamics and progres speed depend on the nature of underlying mechanisms and are characterized by accumulation of ECM elements. They vary from patient to patient and are directly correlated to aberrations of homeostasis degradation and production of liver connective tissue. In liver fibrosis the main source of ECM are hepatic stellate cells (HSCS), although other cells are also able to produce ECM such as: portal fibroblasts, narrow-derived cells, biliary duct epithelial cells and epithelial mesenchymal transition hepatocytes. The HSCS activity is stimulated by proinflammatory cytokines, oxidative and nitrosative stress which lead to different pathologies such as: inflammation, steatosis, fibrosis, cirrhosis, liver-cell cancer. Alcohol, the main fibrotic agents is metabolized almost entirely in the liver, so the organ is extremely sensitive to its negative intermediate and mediate influence. Factors influencing alcoholic liver failure are not only oxidative and nitrosative stress and proinflammatory cytokines activity, but also reductive stress, hepatocytes; hypoxia, mucous membranę dysfunction and intestine flora influence, as well as genetic and immunological factors. Though in last several yers there has been a great advancement in our knowledge of liver fibrosis mechanisms, it remains tough to diagnose the proces in its early stages and consequently apply an efficient therapy. The challenge for the futur is finding useful biomarkers and new therapeutic goals.