ABSTRACTTrypanosoma cruzi, the protozoan parasite that causes human Chagas' disease, induces a type I interferon (IFN) (IFN-α/β) response during acute experimental infection in mice and in isolated primary cell types. To examine the potential impact of the type I IFN response in shaping outcomes in experimentalT. cruziinfection, groups of wild-type (WT) and type I IFN receptor-deficient (IFNAR−/−) 129sv/ev mice were infected with two differentT. cruzistrains under lethal and sublethal conditions and several parameters were measured during the acute stage of infection. The results demonstrate that type I IFNs are not required for early host protection againstT. cruzi. In contrast, under conditions of lethalT. cruzichallenge, WT mice succumbed to infection whereas IFNAR−/−mice were ultimately able to control parasite growth and survive.T. cruziclearance in and survival of IFNAR−/−mice were accompanied by higher levels of IFN-γ production by isolated splenocytes in response to parasite antigen. The suppression of IFN-γ in splenocytes from WT mice was independent of IL-10 levels. While the impact of type I IFNs on the production of IFN-γ and other cytokines/chemokines remains to be fully determined in the context ofT. cruziinfection, our data suggest that, under conditions of high parasite burden, type I IFNs negatively impact IFN-γ production, initiating a detrimental cycle that contributes to the ultimate failure to control infection. These findings are consistent with a growing theme in the microbial pathogenesis field in which type I IFNs can be detrimental to the host in a variety of nonviral pathogen infection models.
Deficiency of the AIM2–ASC Signal Uncovers the STING-Driven Overreactive Response of Type I IFN and Reciprocal Depression of Protective IFN-γ Immunity in Mycobacterial Infection
