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Helminthic infections have been shown to inhibit allergy skin-prick tests and to modify the course of asthma. We evaluated Dermatophagoides pteronyssinus-specific immune responses in patients with asthma by measuring levels of T helper 2 (Th2) cytokines in peripheral blood mononuclear cell (PBMC) cultures. PBMCs from Schistosoma mansoni-infected patients with asthma living in an area of polyhelminthic endemicity produced lower levels of interleukin (IL)-5 and IL-4 in response to D. pteronyssinus antigen (Ag) 1 than did PBMCs from helminth-free patients with asthma. In contrast, D. pteronyssinus Ag 1-specific production of IL-10 was higher in helminth-infected patients than in helminth-free patients. The addition of recombinant human IL-10 to D. pteronyssinus Ag 1-stimulated cultures of PBMCs from helminth-free patients led to down-modulation of production of IL-5. After helminth-infected patients with asthma received antihelminthic treatment, there was down-modulation of D. pteronyssinus Ag 1-specific production of IL-10 in vitro. S. mansoni-infected patients with asthma produce lower levels of Th2 cytokines than do helminth-free patients with asthma, and this modulation is likely done by IL-10.

Periportal fibrosis in schistosomiasis has been associated to the host immune response to parasite antigens. We evaluated the immune response inS. mansoniinfected individuals with different degrees of periportal fibrosis. Cytokine and chemokines were measured in serum and in supernatants of PBMC cultures stimulated with the soluble adult worm (SWAP) or egg (SEA) antigens, using a sandwich ELISA. The levels of IL-5 in response to SEA were higher in individuals with moderate to severe fibrosis (310.9 pg/mL) compared to individuals without fibrosis (36.8 pg/mL;P=0.0418). There was also a higher production of TNF-αin cultures stimulated with SWAP in patients with insipient fibrosis (1446 pg/mL) compared to those without fibrosis (756.1 pg/mL;P=0.0319). The serum levels of IL-13 and MIP-1αwere higher in subjects without fibrosis than in those with moderate to severe fibrosis. However a positive association between serum levels of IL-13, TNF-α, MIP-1α, and RANTES andS. mansoniparasite burden was found. From these data we conclude that IL-5 and TNF-αmay participate in liver pathology in schistosomiasis. The positive association between IL-13, TNF-α, MIP-1α, and RANTES with parasite burden, however, might predict the development of liver pathology.

Protective factors associated with atopy or asthma in rural areas include socioeconomic level, overcrowding, and helminth infection. However, little epidemiological information was originated from schistosomiasis areas. This study aimed to investigate factors associated with asthma in a schistosomiasis endemic area. A questionnaire was used to obtain information on demographics, socioeconomic, and environmental features. The ISAAC questionnaire was used to identify individuals with asthma. Parasitological exam was done in all participants and skin prick test to aeroallergens in all asthmatics. Prevalence ofSchistosoma mansoniinfection was 57.4% andAscaris lumbricoides,30.8%. Asthma was found in 13.1% of the population, and 35.1% of them had a positive SPT. Active and passive smoking was positively associated with asthma, whereasA. lumbricoideswas negatively associated. In a schistosomiasis hyperendemic region, current infection withA. lumbricoidesis protective against asthma. However, we cannot rule out the involvement ofS. mansoniinfection in this process.

This is a prospective, double-blinded, and placebo-controlled trial evaluating the influence of antihelminthic treatments on asthma severity in individuals living in an endemic area of schistosomiasis. Patients from group 1 received placebo of Albendazole or of Praziquantel and from group 2 received Albendazole and Praziquantel. Asthma severity was assessed by clinical scores and by pulmonary function test. There was no significant difference in the asthma scores from D0 to D1–D7 after Albendazole or Praziquantel and from D0 to D30–90 after Albendazole or Praziquantel in both, group 1 and 2. It was observed, however, a clinical worsening of the overall studied population after 6 months and 12 months of antihelminthic treatments. Additionally, we observed increased frequency of forced expiratory volume in 1 second (FEV1)<80% on 12 and 18 months after treatment. The worsening of asthma severity after repeated antihelminthic treatments is consistent with the hypothesis of the protective role conferred by helminths in atopic diseases.

Chronic schistosomiasis induces Th2/T regulatory responses which are able to down-modulate allergic inflammation and asthma. Because co-stimulatory molecules and IL-10 are essential for inducing tolerance, the aim of this study was to determine by flow cytometry, the expression of CD28, CTLA4, CD40L, CD80, CD86, HLA-DR, IL-10 and IL-10 receptor, by mononuclear cells from asthmatic individuals infected with Schistosoma mansoni and compare with non-infected individuals. Peripheral blood mononuclear cells were stained with fluorochrome conjugated antibodies for the expression of co-stimulatory molecules, and for intracellular CTLA4 and IL-10 expression. There was no significant difference in the frequency of T cells expressing CD28 between the two groups. However, the frequency of TCD4(+) cells expressing CTLA4 and CD40L was higher in infected asthmatics. The frequency of monocytes expressing CD80 and CD86 did not differ between groups, while the expression of HLA-DR and IL-10 receptor was higher on monocytes of infected individuals. Furthermore, monocytes and CD4(+)CD25(+) cells of infected individuals expressed higher levels of IL-10. We conclude that, besides alternatively-activated monocytes that are, together with CD4(+)CD25(+) cells, important sources of IL-10, CTLA4 and CD40L expression may also participate in the down-modulation of inflammatory allergic response in S. mansoni-infected asthmatics.