Helicobacter pylori and Immune-mediated Disorders

Abstract

Recently, many studies have reported the potential association of <i>Helicobacter pylori</i> (<i>H. pylori</i>) with various extragastric diseases. <i>H. pylori</i>, a major component of the gastric microbiota, is in symbiosis with humans. It is, therefore, assumed to potentially influence immune homeostasis in humans to some extent. There are several reports highlighting the possible association of <i>H. pylori</i> with allergic diseases. However, these were mainly based on cross-sectional or epidemiological studies. With a greater emphasis on the effects of human microbiota on host immunity and disease development, studies have attempted to explain the association between <i>H. pylori</i> infection and allergic diseases. Nevertheless, no concrete evidence for a causal relationship has been clearly demonstrated yet. The association of <i>H. pylori</i> infection with autoimmune disorders has also been reported in the literature. It has been hypothesized that environmental triggers act on genetically vulnerable hosts, leading to autoimmune disorders. The role of <i>H. pylori</i> infection as one of the triggers in autoimmune diseases has been explored previously. However, the results were conflicting and indistinct with respect to most autoimmune diseases. Similar findings were also detected in skin disorders where <i>H. pylori</i> infection was deemed to be a causative factor. The role of <i>H. pylori</i> in majority of the immune-mediated disorders or skin disorders remains controversial. In this review, the association of <i>H. pylori</i> with various immune-mediated disorders and skin disorders is discussed. The epidemiological, serological, and experimental evidences relevant to the aforementioned association are also addressed.