Cynomolgus macaques naturally infected with Trypanosoma cruzi-I exhibit an overall mixed pro-inflammatory/modulated cytokine signature characteristic of human Chagas disease

Abstract

BackgroundNon-human primates have been shown to be useful models for Chagas disease. We previously reported that natural T. cruzi infection of cynomolgus macaques triggers clinical features and immunophenotypic changes of peripheral blood leukocytes resembling those observed in human Chagas disease. In the present study, we further characterize the cytokine-mediated microenvironment to provide supportive evidence of the utility of cynomolgus macaques as a model for drug development for human Chagas disease.Methods and findingsIn this cross-sectional study design, flow cytometry and systems biology approaches were used to characterize the ex vivo and in vitro T. cruzi-specific functional cytokine signature of circulating leukocytes from TcI-T. cruzi naturally infected cynomolgus macaques (CH). Results showed that CH presented an overall CD4+-derived IFN-γ pattern regulated by IL-10-derived from CD4+ T-cells and B-cells, contrasting with the baseline profile observed in non-infected hosts (NI). Homologous TcI-T. cruzi-antigen recall in vitro induced a broad pro-inflammatory cytokine response in CH, mediated by TNF from innate/adaptive cells, counterbalanced by monocyte/B-cell-derived IL-10. TcIV-antigen triggered a more selective cytokine signature mediated by NK and T-cell-derived IFN-γ with modest regulation by IL-10 from T-cells. While NI presented a cytokine network comprised of small number of neighborhood connections, CH displayed a complex cross-talk amongst network elements. Noteworthy, was the ability of TcI-antigen to drive a complex global pro-inflammatory network mediated by TNF and IFN-γ from NK-cells, CD4+ and CD8+ T-cells, regulated by IL-10+CD8+ T-cells, in contrast to the TcIV-antigens that trigger a modest network, with moderate connecting edges.ConclusionsAltogether, our findings demonstrated that CH present a pro-inflammatory/regulatory cytokine signature similar to that observed in human Chagas disease. These data bring additional insights that further validate these non-human primates as experimental models for Chagas disease.

Trypanosoma cruzi Infection in Non-Human Primates

“…These findings may support, at least in part, the predominance of TcI infection amongst cynomolgus macaques in Southern part of the United States. Figures 4 and 5 present a synthesized scheme of our newest cytokine findings and reinforce the distinct cytokine pattern produced upon T. cruzi TcI and TcIV antigen recall in vitro [22]. Furthermore, other studies have confirmed the presence of both TcI and TcIV isolates from Amazonian primates, TcI being more predominate strain than TcIV [38][39][40].…”

“…The infected animals exhibit higher frequency of NK Granzyme A + cells. Furthermore, this cell population was able to increase the pro-inflammatory cytokine secretion afterwards T. cruzi antigen stimulation [22]. These data reinforce the important role of NK cells as a source of IFN-γ to activate macrophages and increase the nitric oxide production to inhibit the intracellular parasite growth [23,24].…”

“…However, little is known about the cytokine profile during NHP infection with T. cruzi. In order to further understand the mechanisms of T. cruzi infection in NHP, Vitelli-Avelar [22], for the first time, characterized the ex vivo cytokine pattern of cynomolgus macaques naturally infected with T. cruzi and observed an overall mixed pro-inflammatory/regulatory cytokine milieu, mediated by IFN-γ from CD4 + T cells counterbalanced by IL-10 produced by CD4 + T cells and B cells. This microenvironment resembles that previously described for chronic Chagas disease in humans, mainly in indeterminate clinical form [24].…”

“…In this context, our data showed that NHP presents distinct cytokine profile in the presence of TcI and TcIV antigen. While the TcIV antigen triggered an outstanding response, characterized by high levels of TNF-and IFN-γ-producing CD8 + T cells, along with low levels of IL-10, the TcI antigen elicits a predominant regulatory microenvironment, mediated by IL-10 derived from HLA-DR ++ monocytes and T cells with low levels of TNF + CD8 + T cells [22]. The prominent pro-inflammatory milieu, mediated by TNF, seems to be relevant to control the T. cruzi infection NHP.…”

“…Studies focusing on aspects related to the synergic effect of the immune response and chemotherapeutic agents in humans and NPH are still scarce. Sathler-Avelar and colleagues [21,22,24] have provided insights about the relevance of a balanced immune response elicited after chemotherapeutic intervention to mediated parasite killing but minimize tissue damage. There are evidences supporting that a pro-inflammatory response mediated by IFN-γ acts synergistically with the drug treatment to accomplish effective trypanocidal events [24,41] and that simultaneous regulatory mechanisms elicited by IL-10 are relevant to control deleterious effects of therapeutic intervention [21,22,24].…”