Helicobacter pylori infection and respiratory diseases: a review.

In the past few years, a variety of extradigestive disorders, including cardiovascular, skin, rheumatic and liver diseases, have been associated with Helicobacter pylori (H. pylori) infection. The activation of inflammatory mediators by H. pylori seems to be the pathogenetic mechanism underlying the observed associations. The present review summarizes the current literature, including our own studies, concerning the association between H. pylori infection and respiratory diseases. A small number of epidemiological and serologic, case-control studies suggest that H. pylori infection may be associated with the development of chronic bronchitis. A frequent coexistence of pulmonary tuberculosis and H. pylori infection has also been found. Moreover, recent studies have shown an increased H. pylori seroprevalence in patients with bronchiectasis and in those with lung cancer. On the other hand, bronchial asthma seems not to be related with H. pylori infection. All associations between H. pylori infection and respiratory diseases are primarily based on case-control studies, concerning relatively small numbers of patients. Moreover, there is a lack of studies focused on the pathogenetic link between respiratory diseases and H. pylori infection. Therefore, we believe that larger studies should be undertaken to confirm the observed results and to clarify the underlying pathogenetic mechanisms.