Schistosoma mansoni down-regulate type 2 immune response and reduce severity of asthma

Abstract

Rationale Previous studies have shown that helminthic infection decreases skin test response to aeroallergens and herein the severity of asthma and the production of Th2 cytokine were determined in asthmatic patients with S. mansoni infection and without helminthic infections. Methods Severity of asthma was evaluated in 42 asthmatic patients from one endemic area of S. mansoni and a control area endemic for other intestinal parasites except S. mansoni. Additionally, determination of IL-4, IL-5 and IL-10 were performed in 10 patients with asthma and S. mansoni and in 10 with asthma without helminthic infection. Results While in Caatinga do Moura the prevalence of S. mansoni infection was 94%, in Lajes do Batata was 5% (P<0.001). The severity of asthma was lower (p<0.05) in S. mansoni endemic area as compared with individuals living in the endemic area for other helminths. Levels of IL-4 and IL-5 in cultures stimulated with D. pteronissinus were lower in patients with asthma and S. mansoni as compared with those with asthma but without helminthic infection. In contrast, IL-10 was higher in patients with asthma and schistosomiasis than in those with asthma without schistosomiasis. Additionally, IL-10 production was correlated with number of eggs/g/stool and exogenous IL-10 suppressed IL-4 and IL-5 production in D. pteronissinus stimulated cultures. Conclusions Patients living in endemic area of schistosomiasis had less severe asthma and low levels of Th2 cytokines. The decreasing of Th2 cytokines production was correlated with IL-10 production.