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SELECTED ARTICLES FROM THE RECENT LITERATURE 2008
5/21/2008
Protective Role for H. Pylori in Preventing Atopic Disease?
Summary
This article is a review of studies done to assess the relationship of the eradication of H. pylori in the gut with the increasing incidence of atopic disease. The authors cite data that the frequency of H. pylori infection is declining and that this decline correlates with the increase in atopic disease. They attribute the decline to a number of factors including the increased use of antibiotics. They state that, historically, in the past,70 to 90% of children in the United States were infected with H. pylori. This rate is now fewer than 10%.
They also reviewed epidemiologic data correlating the absence of H. pylori with an increased incidence of atopic disease. Perhaps the most impressive of these was from the MHANS III. Data from this investigation showed there was an inverse association of ever having asthma with having the cagA+ H. pylori strain. They state that the inverse association between H. pylori and asthma is independent of socioeconomic status, gender, age, ethnic background, smoking status, and hepatitis A infection. They cite a number of different possible mechanisms to explain this epidemiologically observed phenomenon. Perhaps the most interesting of these is the fact that patients with H. pylori have a gastric population of immunocytes including regulatory T cells which are absent in subjects who are H. pylori negative. They postulate that these immunoregulatory cells may be responsible for diminishing the tendency to atopy and therefore perhaps to asthma.
Comments
These observations are another interesting "twist" to the hygiene hypothesis. H. pylori is transmitted by fecal-oral, hand-oral, and oral-oral transmission. In primitive societies, according to the authors, colonization with H. pylori was almost universal. With industrialization and the institution of hygienic practices, the transmission of H. pylori has declined.
Reference
Blaser MJ, et al. Does Helicobacter pylori protect against asthma and allergy? Gut 2008; 57:561-587.
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