From the stomach to other organs: Helicobacter pylori and the liver.

Many recent studies have examined the importance of Helicobacter pylori (H. pylori) infection in the pathogenesis of the diseases outside the stomach and explored the significance of this bacterium in the pathogenesis of some metabolic and cardiovascular diseases. Recent studies have provided evidence that H. pylori is also involved in the pathogenesis of some liver diseases. Many observations have proved that H. pylori infection is important in the development of insulin resistance, non-alcoholic fatty liver disease, non-alcoholic steatohepatitis, liver fibrosis and cirrhosis. The worsening of liver inflammation of different origins also occurs during H. pylori infection. Some studies have indicated that H. pylori infection induces autoimmunological diseases in the liver and biliary tract. The potential significance of this bacterium in carcinogenesis is unclear, but it is within the scope of interest of many studies. The proposed mechanisms through which H. pylori impacts the development of hepatobiliary diseases are complex and ambiguous. The importance of other Helicobacter species in the development of hepatobiliary diseases is also considered because they could lead to the development of inflammatory, fibrotic and necrotic injuries of the liver and, consequently, to hepatocellular carcinoma. However, many contrary viewpoints indicate that some evidence is not convincing, and further studies of the subject are needed. This review presents the current knowledge about the importance of H. pylori in the pathogenesis of liver and in biliary diseases.