Single nucleotide polymorphisms of cytokine-related genes and association with clinical outcome in a Chagas disease case-control study from Brazil

BACKGROUND The severity of chronic chagasic cardiomyopathy (CCC), the most frequent clinical outcome of Chagas disease (CD), has been associated with cytokine-enriched heart tissue inflammation, and high serum levels of transforming growth factor (TGFβ), interferon-gamma (IFNγ), and tumour necrosis factor (TNF). Conversely, increased interleukin (IL)-10 serum concentrations have been associated with asymptomatic CD. Cytokines and cytokine-related gene polymorphisms may control cytokine expression and have been proposed to contribute to CCC outcomes. OBJECTIVES We evaluated the association of 13 cytokine-related genes (TGFB: rs8179181, rs8105161, rs1800469; IL10: rs1800890, rs1800871, rs1800896; IFNG: rs2430561; TNF: rs1800629; BAT1: rs3853601; LTA: rs909253, rs2239704; TNFR1: rs767455; TNFR2: rs1061624) with risk and progression of CCC. FINDINGS Four hundred and six seropositive patients from CD endemic areas in the state of Pernambuco, north-eastern Brazil, were classified as non-cardiopathic (A, 110) or cardiopathic (mild, B1, 163; severe, C, 133). We found no evidence of TGFB, IL10, TNF, or TNFR1/2 gene polymorphisms associated with CCC risk or progression. Only BAT1 rs3853601 −22G carriers (B1 vs. C: OR = 0.5; p-value = 0.03) and IFNG rs2430561 +874AT (A vs. C: OR = 0.7; p-value = 0.03; A vs. B1+C: OR = 0.8; p-value = 0.02) showed a significant association with protection from cardiopathy in a logistic regression analysis with adjustment for gender and ethnicity; however, the association disappeared after performing adjustment for multiple testing. A systematic review of TNF rs1800629 −308G>A publications included five studies for meta-analysis (534 CCC and 472 asymptomatic patients) and showed no consensus in pooled odds ratio (OR) estimates for A allele or A carriers (OR = 1.4 and 1.5; p-values = 0.14 and 0.15, respectively). In CD patients, TNF serum levels were increased, but not affected by the TNF rs1800629 −308A allele. MAIN CONCLUSIONS Our data suggest no significant contribution of the analysed gene variants of cytokine-related molecules to development/severity of Chagas' heart disease, reinforcing the idea that parasite/host interplay is critical to CD outcomes.

Severity of chronic experimental Chagas' heart disease parallels tumour necrosis factor and nitric oxide levels in the serum: models of mild and severe disease

Heart tissue inflammation, progressive fibrosis and electrocardiographic alterations occur in approximately 30% of patients infected by Trypanosoma cruzi, 10-30 years after infection. Further, plasma levels of tumour necrosis factor (TNF) and nitric oxide (NO) are associated with the degree of heart dysfunction in chronic chagasic cardiomyopathy (CCC). Thus, our aim was to establish experimental models that mimic a range of parasitological, pathological and cardiac alterations described in patients with chronic Chagas’ heart disease and evaluate whether heart disease severity was associated with increased TNF and NO levels in the serum. Our results show that C3H/He mice chronically infected with the Colombian T. cruzi strain have more severe cardiac parasitism and inflammation than C57BL/6 mice. In addition, connexin 43 disorganisation and fibronectin deposition in the heart tissue, increased levels of creatine kinase cardiac MB isoenzyme activity in the serum and more severe electrical abnormalities were observed in T. cruzi-infected C3H/He mice compared to C57BL/6 mice. Therefore, T. cruzi-infected C3H/He and C57BL/6 mice represent severe and mild models of CCC, respectively. Moreover, the CCC severity paralleled the TNF and NO levels in the serum. Therefore, these models are appropriate for studying the pathophysiology and biomarkers of CCC progression, as well as for testing therapeutic agents for patients with Chagas’ heart disease.

Imunoterapia na infecção crônica experimental pelo Trypanosoma cruzi: ação benéfica da pentoxifilina na cardiomiopatia / Immunotherapy in chronic experimental infection with Trypanosoma cruzi: beneficial effect of pentoxifylline in cardiomyopathy

Na cardiomiopatia chagásica crônica (CCC), inflamação e destruição progressiva do tecido cardíaco levam a alterações da condução dos impulsos elétricos e arritmias em cerca de 30 por cento dos pacientes infectados pelo Trypanossoma cruzi 10-30 anos após a infecção.Antígenos do T. cruzi induzem ativação celular que leva à translocação do fator de transcrição NF-KB para o núcleo, resultando na produção do fator de necrose tumoral(TNF). A sinalização de TNF via TNFR1/p55 induz a produção de quimiocinas e óxido nítrico (NO), participando do controle do parasito na fase aguda, mas também revelando o potencial papel de TNF na gênese da inflamação e da disfunção cardíaca. De fato, níveis plasmáticos de TNF estão diretamente correlacionados ao grau de disfunção cardíaca em pacientes portadores da doença de Chagas, sendo também associados à caqueixa e danos teciduais em modelos experimentais. Assim, o objetivo de nosso trabalho é estabelecer modelos experimentais com diferentes graus de cardiomiopatia mimetizando o quadro encontrado em portadores da doença de Chagas, e analisar os efeitos de pentoxifilina (PTX), um fármaco classicamente descrito por inibir a síntese de TNF, na fase crônica da infecção nestes modelos de cardiopatia. Nossos resultados mostraram que os camundongos C3H/He e C57/BL6 infectados pela cepa Colombiana do T. cruzi apresentam diferentes níveis de lesão cardíaca, podendo ser classificados, respectivamente, como portadores de CCC grave e moderada. Em ambos os modelos, o tratamento de PTX promoveu melhora da função cardíaca, diminuindo as arritmias e bloqueios átrio ventriculares de graus 1 e 2,Reduzindo significativamente os níveis de atividade da enzima CK-MB no soro, a perda de conexina 43 (Cx43) no coração e, no modelo de CCC moderada, reduziu a deposição de fibronectina (FN) no tecido cardíaco. Mais do que interferir na progressão da CCC, PTX foi capaz de reverter as alterações cardíacas já instaladas. Além disso, o tratamento com PTX preservou a produção de IFN- no baço e no coração, aumentou a atividade citotóxica das células T CD8+ esplênicas e diminuiu o número de células perforina+ no coração. Estes dados sugerem uma recompartimentalização das células efetoras com atividade citotóxica. Além disso, PTX atua nos processos de migração celular (reduzindo a freqüência de células CD8+ CCR5+ circulantes e a expressão de ICAM-1 no tecido cardíaco) e nos cardiomiócitos in vitro (reduzindo a expressão de FN e a perda de Cx43). Os achados desta pesquisa permitem o estabelecimento de dois modelos experimentais distintos de CCC, grave e moderada e mostram que a PTX é eficaz no tratamento da CCC. Assim, PTX pode tornar-se uma alternativa viável na terapêutica da forma cardíaca crônica da doença Chagas.

Chronic Trypanosoma cruzi-elicited cardiomyopathy: from the discovery to the proposal of rational therapeutic interventions targeting cell adhesion molecules and chemokine receptors: how to make a dream come true

One hundred years ago, Carlos Chagas discovered a new disease, the American trypanosomiasis. Chagas and co-workers later characterised the disease's common manifestation, chronic cardiomyopathy, and suggested that parasitic persistence coupled with inflammation was the key underlying pathogenic mechanism. Better comprehension of the molecular mechanisms leading to clinical heart afflictions is a prerequisite to developing new therapies that ameliorate inflammation and improve heart function without hampering parasite control. Here, we review recent data showing that distinct cell adhesion molecules, chemokines and chemokine receptors participate in anti-parasite immunity and/or detrimental leukocyte trafficking to the heart. Moreover, we offer evidence that CC-chemokine receptors may be attractive therapeutic targets aiming to regain homeostatic balance in parasite/host interaction thereby improving prognosis, supporting that it is becoming a non-phantasious proposal.