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 Trypanosoma cruzi-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 T. cruzi. Although IL-27 has been extensively characterized as a suppressive cytokine that prevents liver immunopathogenesis after T. cruzi infection, the mechanisms underlying its effects on T. cruzi-induced myocarditis remain largely unknown. Here, wild-type (WT) and Ebi3-deficient animals were intraperitoneally infected with trypomastigotes of T. cruzi Y strain and used to evaluate the potential anti-inflammatory properties of Ebi3 during T. cruzi 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 T. cruzi-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 T. cruzi-infected animals. Furthermore, in vivo 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 bona fide culprit of Chagas disease cardiomyopathy.

Regulatory Lymphoid and Myeloid Cells Determine the Cardiac Immunopathogenesis of Trypanosoma cruzi Infection

“…It was recently described using Ebi3 deficient mice (C57BL/6 background) infected with the Y strain, that Ebi3 modulates IFN-γ mediated myocarditis, through IL-10, likely produced by Tr1 cells rather than classical Treg cells. These results in mice were in agreement with the presence of EBI3 polymorphisms in chagasic patients suffering severe cardiomyopathy (Medina et al, 2017 ).…”

Human neutrophils activated by TLR8 agonists, with or without IFNγ, synthesize and release EBI3, but not IL-12, IL-27, IL-35, or IL-39

“…Why the latter occurs remains to be investigated and explained. Given that as a self-standing molecule EBI3 has been, for example, involved in the pathogenesis of rheumatoid arthritis, 48 inflammatory bowel disease, 49 systemic sclerosis, 12 and cardiac inflammation, 50 as well in growth-promoting activity of lung 51 breast, 52 and colorectal cancer, 53…”

Regulatory Role of CD4+T Cells in Myocarditis

“…Mice lacking Regnase-1 and Roquin, RNA-binding proteins that are essential for degradation of inflammatory mRNAs, demonstrated increased expression of IFN- γ , but not IL-17, and suffered from severe inflammation and fibrosis in their hearts [ 134 ]. Dampening IFN- γ overexpression by Ebi3, a compartment of IL-27, prevented T. cruzi- induced myocarditis in mice [ 135 ]. Thus, although some studies indicate a protective role of IFN- γ as a negative regulator of Teff responses, the same cytokine can also contribute to myocardial inflammation and pathological remodeling.…”