Differential role of T regulatory and Th17 in Swiss mice infected with Plasmodium berghei ANKA and Plasmodium yoelii.

The outcome of malaria infection is determined, in part, by the balance of pro-inflammatory and regulatory immune responses. Host immune responses in disease including malaria are finely regulated by the opposing effects of Th17 and T regulatory (Treg) cells. Here we have examined the role of Treg cells and Th17 cells during malaria infection and find that low levels of Treg cells possibly influence the outcome of infections with the lethal strain of Plasmodium berghei ANKA (PbA). In contrast, high level of Treg cells may influence the outcome of nonlethal Plasmodium yoelii NXL (P. yoelii) infections. We observed decreased expressions of key regulators of Treg inductions-TGF-β, CD4IL-2 and IL-10 during PbA infection, whereas their expression remains high during P. yoelii infection. On the other hand TNF-α, IL-6, IFN-γ and IL-23 expression is high during PbA infection and lower during P. yoelii infection. Thus, results from this study suggest that the differential expression of Treg and Th17 might have a key role on host pathogenesis during malaria infection. The high level of IL-6 and low level of TGF-β may composite of the advantaged local microenvironment for the production of Th17 cells in the spleen of the PBA infected mice and vice verse during nonlethal P. yoelii.