endothelin-1 and Chagas-Disease

During Chagas disease, Trypanosoma cruzi alternates between intracellular and extracellular developmental forms. After presenting an overview about the roles of the contact system in immunity, I will review experimental studies showing that activation of the kallikrein-kinin system (KKS) translates into mutual benefits to the host/parasite relationship.. T. cruzi trypomastigotes initiate inflammation by activating tissue-resident innate sentinel cells via the TLR2/CXCR2 pathway. Following neutrophil-evoked microvascular leakage, the parasite's major cysteine protease (cruzipain) cleaves plasma-borne kininogens and complement C5. Tightly regulated by angiotensin-converting enzyme (ACE), kinins and C5a in turn further propagate inflammation via iterative cycles of mast cell degranulation, contact system activation, bradykinin release and activation of endothelial bradykinin B2 receptors (B2R). Recently, studies in the intracardiac model of infection revealed a dichotomic role for bradykinin and endothelin-1: generated upon contact activation (mast cell/KKS pathway), these pro-oedematogenic peptides reciprocally stimulate trypomastigote invasion of heart cells that naturally overexpress B2R and endothelin receptors (ETaR/ETbR).. Studies focusing on the immunopathogenesis of Chagas disease revealed that the contact system plays a dual role in host/parasite balance: T. cruzi co-opts bradykinin-induced plasma leakage as a strategy to increment heart parasitism and increase immune resistance by upregulating type-1 effector T-cell production in secondary lymphoid tissues.

Topics: Chagas Disease; Complement C5a; Endothelin-1; Host-Parasite Interactions; Humans; Immunity, Innate; Kallikreins; Kinins; Peptidyl-Dipeptidase A; Receptor, Bradykinin B2; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Interleukin-8B; Toll-Like Receptor 2; Trypanosoma cruzi

Infection with Trypanosoma cruzi causes a generalised vasculitis of several vascular beds. This vasculopathy is manifested by vasospasm, reduced blood flow, focal ischaemia, platelet thrombi, increased platelet aggregation and elevated plasma levels of thromboxane A(2) and endothelin-1. In the myocardium of infected mice, myonecrosis and a vasculitis of the aorta, coronary artery, smaller myocardial vessels and the endocardial endothelium are observed. Immunohistochemistry studies employing anti-endothelin-1 antibody revealed increased expression of endothelin-1, most intense in the endocardial and vascular endothelium. Elevated levels of mRNA for prepro endothelin-1, endothelin converting enzyme and endothelin-1 were observed in the infected myocardium. When T. cruzi-infected mice were treated with phosphoramidon, an inhibitor of endothelin converting enzyme, there was a decrease in heart size and severity of pathology. Mitogen-activated protein kinases and the transcription factor activator-protein-1 regulate the expression of endothelin-1. Therefore, we examined the activation of mitogen-activated protein kinases in the myocardium by T. cruzi. Western blot demonstrated an extracellular signal regulated kinase. In addition, the activator-protein-1 DNA binding activity, as determined by electrophoretic mobility shift assay, was increased. Increased expression of cyclins A and cyclin D1 was observed in the myocardium, and immunohistochemistry studies revealed that interstitial cells and vascular and endocardial endothelial cells stained intensely with antibodies to these cyclins. These data demonstrate that T. cruzi infection of the myocardium activates extracellular signal regulated kinase, activator-protein-1, endothelin-1, and cyclins. The activation of these pathways is likely to contribute to the pathogenesis of chagasic heart disease. These experimental observations suggest that the vasculature plays a role in the pathogenesis of chagasic cardiomyopathy. Additionally, the identification of these pathways provides possible targets for therapeutic interventions to ameliorate or prevent the development of cardiomyopathy during T. cruzi infection.

Topics: Animals; Chagas Cardiomyopathy; Chagas Disease; Endothelin-1; Gene Expression Regulation; Heart; Humans; Immunohistochemistry; Mice

Trypanosoma cruzi triggers a progressive myocarditis in mammalians through activation and recruitment of leukocytes and release of inflammatory mediators. The chemokine CX3CL1 has been highlighted for its potential role in the parasite controlling in end-pathological status of infected hosts. This study investigated the systemic and cardiac release of CX3CL1 in experimental T. cruzi infection and how this chemokine correlates with endothelin-1 and TNF. Male Fisher rats (n = 20) were infected, or not, by the Y strain of T. cruzi and parasitemia was daily evaluated and immunoassays performed in the cardiac tissue macerated supernatant and in serum to evaluate CX3CL1, endothelin, and TNF production on days 5 and 15 of infection. T. cruzi infection induced a higher serum and cardiac production of these mediators on days 5 and 15 of infection. In both periods of infection, respectively, CX3CL1 showed a positive correlation with TNF (r = 0.833, p < 0.001 and r = 0.723, p < 0.001) and endothelin-1 (r = 0.801, p < 0.05 and r = 0.857, p < 0.001), which reinforce its participation in the T. cruzi-induced myocarditis development.

Topics: Animals; Chagas Disease; Chemokine CX3CL1; Endothelin-1; Male; Myocarditis; Rats; Trypanosoma cruzi

Chronic inflammation, as a consequence of the persistent infection with Trypanosoma cruzi, leads to continuous activation of the immune system in patients with chronic Chagas disease. We have previously shown that increased sera levels of soluble P-selectin are associated with the severity of the cardiomyopathy distinctive of chronic Chagas disease. In this study, we explored the expression of biomarkers of platelet and endothelial activation, tissue remodeling, and mediators of the coagulation cascade in patients at different clinical stages of chronic Chagas heart disease. The frequencies of activated platelets, measured by the expression of CD41a and CD62P were decreased in patients with chronic Chagas disease compared with those in uninfected subjects, with an inverse association with disease severity. Platelet activation in response to adenosine diphosphate was also decreased in T. cruzi-infected subjects. A major proportion of T. cruzi infected subjects showed increased serum levels of fibrinogen. Patients with severe cardiac dysfunction showed increased levels of endothelin-1 and normal values of procollagen I. In conclusion, chronic infection with T. cruzi induced hemostatic alterations, even in those patients who do not yet present cardiac symptoms.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Blood Platelets; Chagas Cardiomyopathy; Chagas Disease; Chronic Disease; Endothelin-1; Female; Fibrinogen; Humans; Inflammation; Male; Middle Aged; P-Selectin; Procollagen; Trypanosoma cruzi; Young Adult

Independent 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 (ET(A)R and ET(B)R) and bradykinin B(2) receptors (B(2)R).. Intravital microscopy was used to determine whether ETR/B(2)R 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 B(2)R (HOE-140), ET(A)R (BQ-123) and ET(B)R (BQ-788), specific IgG antibodies to each GPCRs; cholesterol or calcium-depleting drugs. RNA interference (ET(A)R or ET(B)R genes) in parasite infectivity was investigated in HSMCs.. BQ-123, BQ-788 and HOE-140 reduced leucocyte accumulation in HCP topically exposed to trypomastigotes and blocked inflammatory oedema in infected mice. Acting synergistically, ET(A)R and ET(B)R antagonists reduced parasite invasion of HSMCs to the same extent as HOE-140. Exogenous ET-1 potentiated T. cruzi uptake by HSMCs via ETRs/B(2)R, whereas RNA interference of ET(A)R and ET(B)R genes conversely reduced parasite internalization. ETRs/B(2)R-driven infection in HSMCs was reduced in HSMC pretreated with methyl-β-cyclodextrin, a cholesterol-depleting drug, or in thapsigargin- or verapamil-treated target cells.. Our 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.

Topics: Animals; Bradykinin B2 Receptor Antagonists; Calcium; Cells, Cultured; Chagas Disease; CHO Cells; Cricetinae; Edema; Endothelin A Receptor Antagonists; Endothelin B Receptor Antagonists; Endothelin-1; Human Umbilical Vein Endothelial Cells; Humans; Inflammation; Kinins; Mice; Mice, Inbred BALB C; Myocytes, Cardiac; Myocytes, Smooth Muscle; Receptor, Bradykinin B2; Receptor, Endothelin A; Receptor, Endothelin B; Trypanosoma cruzi

Chagas' disease caused by the parasite, Trypanosoma cruzi, is accompanied by an acute myocarditis which can be fatal. Mice (A/J strain) infected with T. cruzi (Tulahuen strain) develop an acute myocarditis associated with high parasitemia and uniform mortality. Examination of the myocardium demonstrated myonecrosis, vasculitis and parasite pseudocysts. Immunoblot analysis and quantitative real time PCR of heart lysates demonstrated an increased expression of cell cycle regulatory proteins such as cyclins B1, D1, A1 and E1 and an increased expression of cdk2 when compared with uninfected controls. Extracellular signal-regulated kinase (ERK) was activated. Proliferating cell nuclear antigen (PCNA), endothelin-1, endothelin receptor type A (ET(A)) and endothelin receptor type B (ET(B)) expression were increased. Caveolin-1 is important in the regulation of ERK and cyclin D1. The expression of caveolin-1 as well as caveolin-2 and caveolin-3 was reduced. These data suggest that acute fatal T. cruzi myocarditis is accompanied by changes in cell cycle proteins such as the cyclins and caveolin and that the upregulation of the endothelin pathway may be important in the myocardial abnormalities and mortality observed in this mouse model.

Topics: Acute Disease; Animals; Caveolin 1; Chagas Disease; Cyclins; Disease Models, Animal; Endothelin-1; Gene Expression Regulation; Male; Mice; Myocarditis; RNA, Messenger; Trypanosoma cruzi

Trypanosoma cruzi infection causes cardiomyopathy and vasculopathy. Previous studies have demonstrated that infection of human umbilical vein endothelial and smooth muscle cells resulted in activation of extracellular signal-regulated kinase (ERK). In the present study, smooth muscle cells were infected with trypomastigotes, and immunoblot analysis revealed an increase in the expression of cyclin D1 and proliferating cell nuclear antigen (PCNA), important mediators of smooth muscle cell proliferation. Interestingly, after infection, the expression of caveolin-1 was reduced in both human umbilical vein endothelial cells and smooth muscle cells. Immunoblot and immunohistochemical analyses of lysates of carotid arteries obtained from infected mice revealed increased expression of PCNA, cyclin D1, its substrate, phospho-Rb (Ser780), and phospho-ERK1/2. The expression of the cyclin-dependent kinase inhibitor p21(Cip1/Waf1), caveolin-1, and caveolin-3 was reduced in carotid arteries obtained from infected mice. There was an increase in the abundance of pre-pro-endothelin-1 mRNA in the carotid artery and aorta from infected mice. The ET(A) receptor was also elevated in infected arteries. ERK activates endothelin-1, which in turn exerts positive feedback activating ERK, and cyclin D1 is a downstream target of both endothelin-1 and ERK. There was significant incorporation of bromodeoxyuridine into smooth muscle cell DNA when treatment was with conditioned medium obtained from infected endothelial cells. Taken together, these data suggest that T. cruzi infection stimulates smooth muscle cell proliferation and is likely a result of the upregulation of the ERK-cyclin D1-endothelin-1 pathway.

Topics: Animals; Bromodeoxyuridine; Carotid Arteries; Caveolins; Cell Cycle; Cell Proliferation; Cells, Cultured; Chagas Disease; Cyclin D1; Endothelial Cells; Endothelin-1; Extracellular Signal-Regulated MAP Kinases; Humans; Male; Mice; Mice, Inbred A; Mice, Inbred C3H; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Proliferating Cell Nuclear Antigen; Receptor, Endothelin A; RNA Precursors; Trypanosoma cruzi

Topics: Adult; Chagas Cardiomyopathy; Chagas Disease; Chronic Disease; Endothelin-1; Female; Humans; Male; Middle Aged; Radioimmunoassay

Chagas' disease, caused by the parasite Trypanosoma cruzi, is an important cause of heart disease. Previous studies from this laboratory revealed that microvascular spasm and myocardial ischemia were observed in infected mice. Infection of endothelial cells with this parasite increased the synthesis of biologically active endothelin-1 (ET-1). Therefore. in the myocardium of T. cruzi-infected mice, we examined ET-1 expression and the p42/44-mitogen activated protein kinase (MAPK)-AP-1 pathway that regulates the expression of ET-1. There was parasitism and myonecrosis in the myocardium of infected C57BL/6 mice. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis revealed elevated mRNA expression of transcription factor AP-1 (c-jun and c-fos) and increased AP-1 DNA binding activity as determined by electrophoretic mobility shift assay (EMSA). Western blot analysis demonstrated an increase in the phosphorylated forms of extracellular signal-regulated kinase (ERK1/2). ET-1 mRNA was upregulated in the myocardium of infected mice. Immunohistochemical and immunoelectron microscopy using anti-ET-1 antibody detected increased expression in cardiac myocytes and endothelium of these mice. These data suggest that ET-1 contributes to chagasic cardiomyopathy and that the mechanism of the increased expression of ET-1 is a result of the activation of the MAPK pathway by T. cruzi infection.

Topics: Animals; Chagas Disease; Endothelin-1; Enzyme Activation; Male; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; Mitogen-Activated Protein Kinases; Myocardium; RNA, Messenger; Transcription Factor AP-1