Ebi3 Prevents Trypanosoma cruzi-Induced Myocarditis by Dampening IFN-γ-Driven Inflammation

Abstract

The identification of anti-inflammatory mediators can reveal important targetable molecules capable of counterbalancing <i>Trypanosoma cruzi</i>-induced myocarditis. Composed of Ebi3 and IL-27p28 subunits, IL-27 is produced by myeloid cells and is able to suppress inflammation by inducing IL-10-producing Tr1 cells, thus emerging as a potential candidate to ameliorate cardiac inflammation induced by <i>T. cruzi</i>. Although IL-27 has been extensively characterized as a suppressive cytokine that prevents liver immunopathogenesis after <i>T. cruzi</i> infection, the mechanisms underlying its effects on <i>T. cruzi</i>-induced myocarditis remain largely unknown. Here, wild-type (WT) and Ebi3-deficient animals were intraperitoneally infected with trypomastigotes of <i>T. cruzi</i> Y strain and used to evaluate the potential anti-inflammatory properties of Ebi3 during <i>T. cruzi</i> infection. The survival rates of mice were daily recorded, the frequency of inflammatory cells was analyzed by flow cytometry and inflammatory mediators were measured by ELISA, real-time PCR and PCR array. We reported that <i>T. cruzi</i>-induced myocarditis was prevented by Ebi3. Stressors mainly recognized by TLR2 and TLR4 receptors on myeloid cells were essential to trigger IL-27p28 production. In addition, Ebi3 regulated IFN-γ-mediated myocarditis by promoting an anti-inflammatory environment through IL-10, which was most likely produced by Tr1 cells rather than classical regulatory T cells (Tregs), in the heart tissue of <i>T. cruzi</i>-infected animals. Furthermore, <i>in vivo</i> IFN-γ blockade ameliorated the host survival without compromising the parasite control in the bloodstream. In humans, IL-27p28 was correlated with cardiac protection during Chagas disease. Patients with mild clinical forms of the disease produced high levels of IL-27p28, whereas lower levels were found in those with severe forms. In addition, polymorphic sites at Ebi3 gene were associated with severe cardiomyopathy in patients with Chagas disease. Collectively, we describe a novel regulatory mechanism where Ebi3 dampens cardiac inflammation by modulating the overproduction of IFN-γ, the <i>bona fide</i> culprit of Chagas disease cardiomyopathy.