Self and parasite-derived peptides selected upon DERAA-bearing HLA-DRB1 alleles activate CD4+ T cells from Chagas cardiomyopathy patients and are associated with ventricular dysfunction

Thaiany Souza-Silva ¹ Eula Graciele Amorim Neves ¹ Andrea Teixeira-Carvalho ² Amanda Figueiredo ³ Katia Luciano Morais ³ Juliana Apostólico ³ Hélcio Rodrigues ⁴ Jorge Kalil ⁴ Maria Aparecida Juliano ⁵ Luiz Juliano ⁵ Silvana Silva Araújo ¹ Alexandre Pantaleão ¹ Antônio Mutarelli ¹ Maria Nunes ¹ Kenneth J Gollob ^3,6 Walderez Ornelas Dutra ^1,6*

• ¹ Federal University of Minas Gerais, Belo Horizonte, Brazil
• ² René Rachou Institute, Oswaldo Cruz Foundation (Fiocruz), Belo Horizonte, Minas Gerais, Brazil
• ³ Albert Einstein Israelite Hospital, São Paulo, São Paulo, Brazil
• ⁴ Heart Institute (InCor), São Paulo, Sao Paulo, Brazil
• ⁵ Federal University of São Paulo, São Paulo, São Paulo, Brazil
• ⁶ Instituto Nacional de Ciência e Tecnologia de Doenças Tropicais (INCT-DT), Salvador, Bahia, Brazil

Human infection with the protozoan Trypanosoma cruzi causes Chagas disease, which may lead to a deadly dilated cardiomyopathy resulting from T-cell-mediated inflammation. We found that specific HLA-DRB1 alleles (*0103, *0402, *1301, and *1302) that display the DERAA motif are linked to this severe clinical manifestation of Chagas disease. We employed computational analysis, in vitro functional assays, and single-cell RNA sequencing to determine the response of CD4+ T cells from indeterminate (IND) and cardiac (CCC) Chagas patients to peptides selected on DERAA-bearing alleles. We observed that these alleles display binding affinity towards host-derived peptides with sequence similarity to parasite-derived proteins. These peptides can activate and induce proliferation of CD4+ T-cells from CCC, but not IND. Importantly, the magnitude of this response correlated with the severity of ventricular dysfunction and increased production of soluble factors associated with myocardial fibrosis. Analysis of differentially expressed genes (DEGs) in activated CD4+ T-cells from individuals with the DERAA-DRB1 alleles demonstrated a high expression of cytotoxic, chemotactic and proapoptotic genes, linking these cells with pathogenic functions. Finally, we observed the upregulation of genes that code for the host proteins that contain the potentially pathogenic peptides in the cardiac tissue of CCC, suggesting their involvement in cardiomyopathy. Our findings highlight the ability of CD4+ T-cells from CCC patients to recognize and react to foreign and self-peptides, thereby emphasizing the importance of HLA-DRB1 alleles in the presentation of potentially pathogenic antigens and in the amplification of CCC pathology.