Immune response in Mansonella ozzardi infection modulated by IL-6/IL-10 axis in Amazon region of Brazil

Mansonellosis is an endemic disease in the South and Central America. In Brazil, one of the etiological agents is Mansonella ozzardi. This filarial infection is yet poorly understood, with a controversial morbity, presenting since a oligosymptoms, malaria-like signs or without complaint in humans. The knowledge of the human immune response to microfilariae infection is limited mainly by different evolutionary cycles of the parasite in the host. In addition, the prevalence of this filarial parasite infection is high in several regions of Amazonas State. A cross-sectional study was conducted in an endemic area for microfilariae of M. ozzardi (MF) infection in the Amazonas State, Brazil. Proinflammatory and regulatory cytokines (IL-2, IL-4, IL-6, IL-10, TNF, IFN-gamma, and IL-17A) were measured in cryopreserved serum using the Cytometric Bead Array techniques (CBA) in 54 patients diagnosed with M. ozzardi infection and 55 individuals without the infection were included in the study (Controls). The IL-4, IL-6 and IL-10 level increased in infected patients with MF infection, while IL-17A increased in control only. When we compared controls to patients with high or low parasite load, the increased level of IL-6 and IL-10 were maintained. IL-6 contributes to the proinflammatory activity and IL-10 modulates Th1, Th2 and Th17 immune response. Furthermore, IL-4 was detected as a marker in the MF infection and MF patients with low parasite load, indicating the action of the Th2 cell response. The complex network of cytokines acting during M. ozzardi infection depends on a fine balance to determine a host protective effect or filarial persistence. Therefore, these results suggest that the immune response in MF infection is modulated by IL-6/IL-10 axis.