Trypanosoma cruzi invades host cells through the activation of endothelin and bradykinin receptors: a converging pathway leading to chagasic vasculopathy

Abstract

BACKGROUND AND PURPOSEIndependent studies in experimental models of Trypanosoma cruzi appointed different roles for endothelin-1 (ET-1) and bradykinin (BK) in the immunopathogenesis of Chagas disease. Here, we addressed the hypothesis that pathogenic outcome is influenced by functional interplay between endothelin receptors (ETAR and ETBR) and bradykinin B2 receptors (B2R). EXPERIMENTAL APPROACHIntravital microscopy was used to determine whether ETR/B2R drives the accumulation of rhodamine-labelled leucocytes in the hamster cheek pouch (HCP). Inflammatory oedema was measured in the infected BALB/c paw of mice. Parasite invasion was assessed in CHO over-expressing ETRs, mouse cardiomyocytes, endothelium (human umbilical vein endothelial cells) or smooth muscle cells (HSMCs), in the presence/absence of antagonists of B2R (HOE-140), ETAR (BQ-123) and ETBR (BQ-788), specific IgG antibodies to each GPCRs; cholesterol or calcium-depleting drugs. RNA interference (ETAR or ETBR genes) in parasite infectivity was investigated in HSMCs. KEY RESULTSBQ-123, BQ-788 and HOE-140 reduced leucocyte accumulation in HCP topically exposed to trypomastigotes and blocked inflammatory oedema in infected mice. Acting synergistically, ETAR and ETBR antagonists reduced parasite invasion of HSMCs to the same extent as HOE-140. Exogenous ET-1 potentiated T. cruzi uptake by HSMCs via ETRs/B2R, whereas RNA interference of ETAR and ETBR genes conversely reduced parasite internalization. ETRs/B2R-driven infection in HSMCs was reduced in HSMC pretreated with methyl-b-cyclodextrin, a cholesterol-depleting drug, or in thapsigargin-or verapamil-treated target cells. CONCLUSIONS AND IMPLICATIONSOur findings suggest that plasma leakage, a neutrophil-driven inflammatory response evoked by trypomastigotes via the kinin/endothelin pathways, may offer a window of opportunity for enhanced parasite invasion of cardiovascular cells. LINKED ARTICLE

Myeloid‐derived suppressor cells are key players in the resolution of inflammation during a model of acute infection

“…Taking into account that mature macrophages (F4/80 + ) produce elevated levels of NO and that M-MDSCs may express F4/80 marker [34,35], our results revealed that about 20% of MDSCs coexpress F4/80 (data not shown). In addition, a cross-talk between MDSCs and macrophages subverts type 1 toward type 2 immunity [36].…”

“…A suppressive mechanism mediated by NO during T. cruzi infection has previously been reported [22]. When MDSCs were isolated and added to the cultures, the suppressive activity was partial, suggesting that other cells, likely regulatory T cells, might be also exerting the suppressive activity during the acute infection [33].Taking into account that mature macrophages (F4/80 + ) produce elevated levels of NO and that M-MDSCs may express F4/80 marker [34,35], our results revealed that about 20% of MDSCs coexpress F4/80 (data not shown). In addition, a cross-talk between MDSCs and macrophages subverts type 1 toward type 2 immunity [36].…”

C5a and Bradykinin Receptor Cross-Talk Regulates Innate and Adaptive Immunity in Trypanosoma cruzi Infection

“…These results implied that C3a, acting cooperatively with the released kinins, might fuel the infection-associated inflammatory response, hence compensating for the deficient production of C5a anaphylatoxins in A/J mice. It remains to be determined whether the hyperreactivity of the microvasculature of infected A/J mice pretreated with captopril only reflects upregulated ACE activity and/or results from enhanced activation of the kinin/endothelin pathway (40,52) in the C5-deficient strain. Given that the inflammatory edema was measured shortly after TCT injection in naive mice, we may surmise that generation of C5a and C3a resulted from complement activation by Abindependent mechanisms.…”

“…In previous studies, we demonstrated that TCT (Dm28 strain) induce inflammatory edema in mice through the sequential activation of TLR2, CXCR2, B 2 R, and ETaR/ETbR (38,40,48). Using intravital microscopy, we now asked whether C5aRA could inhibit plasma leakage otherwise evoked by the topical application of TCT to the stroma of the HCP.…”

“…Briefly, we have previously shown that kinins, acting cooperatively with endothelins, stimulate parasite invasion of a broad range of nonphagocytic cells, including cardiomyocytes, through the cross-talk between B 2 R/endothelin receptors (36,37,40). Beyond contributing to parasite virulence, BK acts as a Th1-directing adjuvant of endogenous origin by stimulating IL-12 production by DCs via B 2 R (41,42).…”