Circulating antibodies from human and murine chagasic sera are able to interact with myocardium-activating neurotransmitter receptors. Here we reported the presence of autoantibodies against the second extracellular loop of the human heart muscarinic acetylcholine receptors (mAChR) in patients with Chagas' disease by using a synthetic 24-mer peptide in immunoblotting and enzyme immunoassay. Affinity-purified antipeptide IgG from chagasic patients, similar to monoclonal antihuman M2 mAChR, recognized bands with a molecular weight corresponding to the cardiac mAChR. The binding was inhibited by the peptide, assessing the specificity of the interaction. The antipeptide autoantibody also displayed an "agonist-like" activity modifying the intracellular events associated with mAChR activation, i.e., decreased contractility, increased cGMP, and decreased cAMP production. All of these effects on rat atria by chagasic antipeptide autoantibodies resemble the effects of the authentic agonist and those of the total polyclonal chagasic IgG, being selectively blunted by atropine and neutralized by the synthetic peptide corresponding in aminoacid sequence to the second extracellular loop of the human M2 mAChR. A clinical relevance of these findings is demonstrated by a strong association between the existence of circulating antipeptide autoantibodies in chagasic patients and the presence of dysautonomic symptoms, making these autoantibodies a proper early marker of heart autonomic dysfunction.

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Problem The specialized regulatory T cells (Treg) population, essential for maternal tolerance of the fetus, performs its suppressive actions in the critical peri-implantation phase of pregnancy. In the present work, we investigated whether trophoblast cells are able to induce Treg recruitment, differentiation, and whether these mechanisms are modified by a bacterial or viral infection. Method of Study Human T-regulatory cells were differentiated from naïve CD45RA+CCR7+ cells obtained from PBMCs cultured with IL-2 and TGFβ over 5 days. Induction of iTregs (CD4+Foxp3+ cells) was evaluated using low serum conditioned media (LSCM), obtained from two first trimester trophoblast cell lines, Swan-71 and HTR8. Co-culture experiments were done using transwell assays where trophoblast cells were in the absence or presence of PGN, LPS, or Poly [I:C]. Cytokine production was measured by multiplex analysis. Results Trophoblast cells constitutively secrete high levels of TGFβ and induced a significant increase of Foxp3 expression accompanied by a specific T-reg cytokine profile. Moreover, trophoblast cells were able to recruit iTregs in a specific-manner. Conclusion We demonstrate that trophoblast cells have an active role on the recruitment and differentiation of iTregs; therefore, contributing to the process of immune regulation at the placental-maternal interface.