CD39 expression by regulatory T cells drives CD8+ T cell suppression during experimentalTrypanosoma cruziinfection

Abstract

AbstractAn imbalance between suppressor and effector immune responses may preclude cure in chronic parasitic diseases. In the case ofTrypanosoma cruziinfection, specialized regulatory Foxp3+ T (Treg) cells suppress protective type-1 effector responses. Herein, we investigated the kinetics and underlying mechanisms behind the regulation of protective parasite-specific CD8+ T cell immunity during acuteT. cruziinfection. Using the DEREG mouse model, we found that Treg cells play a critical role during the initial stages afterT. cruziinfection, subsequently influencing CD8+ T cells. Early Treg cell depletion increased the frequencies of polyfunctional short-lived, effector T cell subsets, without affecting memory precursor cell formation or the expression of activation markers. In addition, Treg cell depletion during early infection minimally affected the antigen-presenting cell response but it boosted CD4+ T cell responses before the development of anti-parasite effector CD8+ T cell responses. Crucially, the absence of CD39 expression on Treg cells significantly bolstered effector parasite-specific CD8+ T cell responses, leading to improved parasite control duringT. cruziinfection. Our work underscores the crucial role of Treg cells in regulating protective anti-parasite immunity and provides evidence that CD39 expression by Treg cells represents a key immunomodulatory mechanism in this infection model.