Helicobacter pylori infection and autoimmune diseases; Is there an association with systemic lupus erythematosus, rheumatoid arthritis, autoimmune atrophy gastritis and autoimmune pancreatitis? A systematic review and meta-analysis study.

Autoimmune diseases are considered as one of the most important disorders of the immune system, in which the prolonged and chronic processes eliminate self-tolerance to the auto-antigens. The prevalence of autoimmune diseases has been increasing worldwide in the recent years. According to the literature, biological processes such as the host genome, epigenetic events, environmental condition, drug consumption, and infectious agents are the most important risk factors that make the host susceptible to the development of autoimmune diseases. In the recent years, the role of Helicobacter pylori in the induction of autoimmune diseases has attracted extensive attention. Via molecular mimicry, epitope spreading, bystander activation, polyclonal activation, dysregulation in immune response, and highly immune-dominant virulence, such as cagA, H. pylori causes tissue damage, polarity, and proliferation of the host cells leading to the modulation of host immune responses. Moreover, given the large population worldwide infected with H. pylori, it seems likely that the bacterium may develop into autoimmune diseases through dysregulation of the immune response. The frequency and relationship between H. pylori infection and systemic lupus erythematosus, rheumatoid arthritis, autoimmune atrophy gastritis, and autoimmune pancreatitis were evaluated using the data from 43 studies involving 5052 patients. According to statistical analysis it is probable that infection with more virulent strains of H. pylori (such as H. pylori cagA positive) can increase the risk of autoimmune diseases. In addition, it was shown that infection with H. pylori can prevent the development of atrophic gastritis by stimulating inflammation in the gastric antrum. However, future studies should confirm the validity of this study.