CD4⁺ T cells from chronic Chagas disease patients with different degrees of cardiac compromise exhibit distinct expression patterns of inhibitory receptors TIGIT, Tim-3 and Lag-3

Abstract

T cells are central to adaptive immune response against T. cruzi infection. In the chronic stage of Chagas disease, circulating parasite-specific memory T cells show reduced functionality and increased expression of inhibitory receptors, possibly as a result of persistent antigenic stimulation. This exhausted phenotype has been linked to progression of cardiac pathology while, contrariwise, the presence of polyfunctional T cells shows association with therapeutic success and more efficient control of infection.Given this, we hypothesized that inhibitory receptors TIGIT, Tim-3 and Lag-3 may be involved in immune modulation of anti-T. cruzi T cell response, and therefore may play a role in the containment or the unleashing of inflammatory phenomena that ultimately lead to tissue damage and pathology. In this preliminary study, we assess the frequency of CD4 + T cells expressing each of these receptors and their relation to cellular activation.Samples from chronic Chagas disease patients with different degrees of cardiac compromise, and non-infected donors were analyzed under different stimulation conditions. Our results show that the frequency of TIGIT + CD4 + T cells is increased in Chagas patients, while Tim-3 + cells are more abundant in patients with signs of cardiac alterations. In addition, the frequency of Lag-3 + cells increases in non-activated CD4 + T cells from Chagas patients without demonstrable cardiopathy upon pathogen-specific in vitro antigenic stimulation.

Activation‐induced marker assays for identification of Trypanosoma cruzi‐specific CD4 or CD8 T cells in chronic Chagas disease patients

“…The individual expression of some activation markers, that is, CD25, HLA-DR and CD69, were mainly explored to interrogate the ability of certain T. cruzi proteins to elicit cellular response in patients with CCD [7,44,45]. However, to our knowledge, we are the first using any combination of surface markers in AIM assay to measure in vitro agnostic CD4 + T-cell activation in the context of this infection [13]. Nowadays, this experimental approach is widely exploited to examine SARS-CoV-2-specific T-cell responses in different scenarios, means in active infection and its evolution, in healthy or sick people as well as in vaccinated individuals [16,18,[46][47][48].…”

“…Gate-pathway used to select this cell subset is graphed in Figure S1. CCD patients and NI subjects stimulated in vitro with parasite lysate during 12 or 24 h, considering the kinetics of each activation markers and stimulation time used in previous studies [11,[13][14][15][16][17][18][19][20][21][22][23][24][25][26]35]. Although the expression profile of these molecules is variable upon antigen stimulation, and some of them peak later, that is, OX40 at 48 h [36], these time constraints were chosen to capture their simultaneous upregulation in the AIM combinations.…”

“…The expression of both markers augmented equally in CD4 + T cells from CCD patients and naïve controls when treated with the non‐specific stimulus of phytohaemagglutinin (PHA), denoting that the combination of OX40 and CD25 can be used in an AIM assay to distinguish T . cruzi ‐stimulated from non‐stimulated CD4 + T cells in patients with CCD [13].…”

“…In general, this approach needs the combination of two surface markers, but it has also been described the need to add other markers to detect T cells, mainly CD8 + lymphocytes, specific for their cognate antigens [12]. In our work where the expression of inhibitory receptors TIGIT, TIM-3 and LAG-3 were analysed in activated and non-activated CD4 + T cells from patients with CCD, we chose OX40 (CD134)/CD25 AIM assay [13] that have previously shown is highly efficient at detecting antigen-specific CD4 + T cells against different preparations from virus and bacteria [10,11]. In our hands, we observed that the frequency of activated or OX40 + CD25 + CD4 + T cells increased in patients with CCD, but not in naïve controls, when cells were stimulated with the parasite antigens derived from trypomastigotes (infective form of T. cruzi in mammals) belonging to Sylvio strain.…”

“…Remarkably, no difference was observed in the expression of OX40 + CD25 + in CD4 + T cells between patients undergoing the different clinical stages of T. cruzi infection, meaning those without any demonstrable symptoms (or asymptomatic) and subjects with cardiac disorders. The expression of both markers augmented equally in CD4 + T cells from CCD patients and naïve controls when treated with the non-specific stimulus of phytohaemagglutinin (PHA), denoting that the combination of OX40 and CD25 can be used in an AIM assay to distinguish T. cruzi-stimulated from nonstimulated CD4 + T cells in patients with CCD [13].…”