Helicobacter pylori infection and the respiratory system: a systematic review of the literature.

BACKGROUND: Recent studies suggest an increased Helicobacter pylori prevalence in patients with various extradigestive inflammatory diseases. Similar to H. pylori infection, many respiratory diseases are characterized by chronic inflammation as well as increased immune response. Recent studies have evaluated the relation between various respiratory disorders and H. pylori infection. The aim of this systematic review was to scrutinize the relevant literature and the mechanisms that could underlie a role for H. pylori infection in respiratory diseases.
METHODS: Relevant literature regarding pathophysiological mechanisms and clinical epidemiology of H. pylori and different respiratory diseases has been systematically identified and analyzed by two independent reviewers according to a PubMed search for English language (until week 14, April 2010).
CONCLUSIONS: At present, there is no definite proof of a causal relationship between H. pylori and respiratory diseases. Both H. pylori and various respiratory diseases are characterized by the release of proinflammatory cytokines and attraction of granulocytes as well as B- and T-cell-mediated response, though a pathophysiological association has not been proven. Neither the role of genetic predisposition of the host nor the presence of virulence factors nor the impact of H. pylori eradication have been studied in detail and definitely need further evaluation.