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.

Trypanosoma cruzi: parasite persistence in tissues in chronic chagasic Brazilian patients

Chagas disease in the chronic phase may develop into cardiac and/or digestive forms. The pathogenesis of the disease is not yet clear and studies have been carried out to elucidate the role of parasite persistence in affected organs. The aim of this study was to detect and quantify Trypanosoma cruzi in paraffin-embedded tissue samples from chronic patients using NPCR (nested polymerase chain reaction) and QPCR (quantitative polymerase chain reaction) methods. These results were correlated to anatomopathological alterations in the heart and gastrointestinal tract (GIT). Of the 23 patients studied, 18 presented the cardiac form and five presented the cardiodigestive form of Chagas disease. DNA samples were randomly isolated from formalin-fixed paraffin-embedded sections of heart and GIT tissue of 23 necropsies and were analyzed through NPCR amplification. T. cruzi DNA was detected by NPCR in 48/56 (85.7 percent) heart and 35/42 (83.3 percent) GIT samples from patients with the cardiac form. For patients with the cardiodigestive form, NPCR was positive in 12/14 (85.7 percent) heart and in 14/14 (100 percent) GIT samples. QPCR, with an efficiency of 97.6 percent, was performed in 13 samples (11 from cardiac and 2 from cardiodigestive form) identified previously as positive by NPCR. The number of T. cruzi copies was compared to heart weight and no statistical significance was observed. Additionally, we compared the number of copies in different tissues (both heart and GIT) in six samples from the cardiac form and two samples from the cardiodigestive form. The parasite load observed was proportionally higher in heart tissues from patients with the cardiac form. These results show that the presence of the parasite in tissues is essential to Chagas disease pathogenesis.

Diagnostico molecular de doença de Chagas em pacientes soronegativos portadores de megaesofago / Molecular diagnosis of Chagas disease in seronegative patients with megaesophagus

A doença de Chagas, cujo agente etiológico é o protozoário Trypanosoma cruzi, completa 100 anos de descoberta. Apesar da implementação de programas visando ao controle da transmissão vetorial, a infecção chagásica segue como um importante problema de saúde pública na América Latina. A globalização da doença de Chagas, consequente à migração de pessoas infectadas para países onde a doença não é endêmica, traz à tona a necessidade de instituição de medidas de controle e vigilância em algumas áreas da Europa e da América do Norte. A patologia caracteriza-se por uma fase aguda geralmente assintomática com elevada parasitemia e uma fase crônica, em que os parasitos dificilmente são detectados no sangue periférico por métodos parasitológicos convencionais. O curso clínico da infecção por T. cruzi é variável, sendo que boa parte dos infectados permanece na formaindeterminada da doença enquanto outros desenvolvem a forma cardíaca, digestiva ou nervosa. A prevalência do comprometimento do trato digestivo na doença de Chagas varia conforme a área endêmica, podendo alcançar até 14% no Brasil central. A forma digestiva caracteriza-se por lesão dos plexos nervosos intramurais e disfunção motora principalmente do esôfago e do cólon, levando à dilatação progressiva desses órgãos. Em nosso país, a doença de Chagas é o único fator etiológico comprovado para o megaesôfago. Devido à parasitemia baixa e intermitente, o diagnóstico na fase crônica baseia-se na detecção de anticorpos específicos anti-T.cruzi por metodologias sorológicas convencionais. Apesar de serem considerados métodos sensíveis e que apresentam boa especificidade, há relatos de resultados falso-positivos devido à reação cruzada com outros tripanosomatídeos que circulam na mesma...

After 100 years of research and despite control programs launched in endemic areas, Chagas disease, caused by Trypanosoma cruzi, still remains an important public health problem in Latin America. Immigration of infected persons from endemic to nonendemic areas leads to Chagas disease spread and it increases the need for establishment of control programs and surveillance in North America and some European countries. Acute phase of Chagas disease is usually free of symptoms and a high parasitemia is observed. Following the acute phase, the chronic stage is characterized by low and intermittent parasitemia. Presentation of chronic chagasic infection is pleomorphic ranging from absence of symptoms to severe cardiac involvement. Symptomatic chronic phase is usually characterized by cardiac or digestive commitment and its current diagnosis relies on the measurement of T. cruzi-specific antibodies produced in response to the infection. Motility disorders and enlargement of digestive organs (commonly esophagus and colon) are consequences of neuronal destruction caused by the persistence of T. cruzi. Since idiopathic megaesophagus is a rare condition in Brazil, Chagas disease is considered the main etiology of megaesophagus. Despite its high sensitivity, conventional serology may present false-positive results due to cross-reactivity to other trypanosomes. On the other hand, false-negative results have been described in patients from endemic areas with suggestive signs of chagasic infection. In order to clarify this controversial situation, alternative methods such as PCR (polymerase chain reaction) have been employed for...