In areas where schistosomiasis is endemic, a negative correlation is observed between atopy and helminth infection, associated with a low prevalence of asthma. We investigated whether Schistosoma mansoni infection or injection of parasite eggs can modulate airway allergic inflammation in mice, examining the mechanisms of such regulation. We infected BALB/c mice with 30 S. mansoni cercariae or intraperitoneally injected 2,500 schistosome eggs, and experimental asthma was induced by ovalbumin (OVA). The number of eosinophils in bronchoalveolar lavage fluid was higher in the asthmatic group than in asthmatic mice infected with S. mansoni or treated with parasite eggs. Reduced Th2 cytokine production, characterized by lower levels of interleukin-4 (IL-4), IL-5, and immunoglobulin E, was observed in both S. mansoni-treated groups compared to the asthmatic group. There was a reduction in the number of inflammatory cells in lungs of S. mansoni-infected and egg-treated mice, demonstrating that both S. mansoni infection and the egg treatment modulated the lung inflammatory response to OVA. Only allergic animals that were treated with parasite eggs had increased numbers of CD4 ؉ CD25 ؉ Foxp3 ؉ T cells and increased levels of IL-10 and decreased production of CCL2, CCL3, and CCL5 in the lungs compared to the asthmatic group. Neutralization of IL-10 receptor or depletion of CD25 ؉ T cells in vivo confirmed the critical role of CD4 ؉ CD25 ؉ Foxp3 ؉ regulatory T cells in experimental asthma modulation independent of IL-10.The prevalence of allergic diseases such as asthma has increased markedly over the past few decades (5). The immune response to allergens is characterized by eosinophilic inflammation of the airways, airway hyperreactivity, and immunoglobulin E (IgE) production by B cells (39). The immune etiology of asthma is complex. Genetic and immunological analyses of atopic individuals have revealed that Th2 cytokines are usually associated with allergies (23, 25). Furthermore, Th2 cells which produce interleukin-4 (IL-4), IL-5, and IL-13 mediate the inflammatory reaction in the lung. Production of IL-5 increases differentiation, recruitment, and survival of eosinophils and therefore plays an important role in the development of pulmonary eosinophilia during allergic disorders (26). Moreover, IL-13 is important for IgE production, mucus hyperplasia, and eosinophilia (34). The levels of these cytokines are higher in allergic patients and play a direct role in the inflammatory response.It has been suggested that people in developing countries suffer less from allergic disease than those who live in industrialized countries because the former are frequently exposed to bacteria and helminth infections associated with poverty and lack of basic sanitary conditions (21). Both helminth infections and allergic diseases are associated with Th2 cytokines and high levels of IgE and eosinophilia. Though they appear to have similar immune responses, a negative correlation between helminth infection and allergic disease has been obse...

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Altogether our results demonstrate that heart failure in Chagas' disease may occur due to electrical and mechanical remodeling of cardiac myocytes, and suggest that AKT/PI3K/NO axis could be an important pharmacological target to improve the disease outcome.

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