The mutual influence of nematode infection and allergy.

Several studies have now shown that the prevalence of helminth infections is negatively correlated with the prevalence and/or severity of allergic diseases. Here, we describe studies in rodents infected with Strongyloides venezuelensis examining the mutual influence of nematode infection and allergy. S. venezuelensis has a lung cycle, much akin to the human hookworm and Strongyloidiasis, and induces airway eosinophilia, local IgE and mucus production, and airway hyperreactivity. Both the Th2 and functional responses are relevant for the ability of rodents to deal with S. venezuelensis infection. Nevertheless, the parasite elicits the release of cytokines, such as IL-10, which are capable of regulating immune and functional manifestations. In infected animals, allergic inflammation prevents parasite migration and establishment. Nevertheless, the parasite is capable of regulating the allergic response, preventing part of the tissue damage and functional changes induced by allergy. Understanding the mechanisms by which helminths regulate inflammation may potentially lead to the development of strategies aimed at controlling unwanted inflammation in allergic and autoimmune diseases.