Banca de DEFESA: BRENO CARDIM BARRETO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : BRENO CARDIM BARRETO
DATA : 19/06/2019
HORA: 14:00
LOCAL: Auditótio Aluízio Prata - Instituto Gonçalo Moniz/FIOCRUZ
TÍTULO:

CHARACTERIZATION OF EXPRESSION OF MYOCARDIC CONEXIN 43 IN CHRONIC CHAGAS DISEASE

PALAVRAS-CHAVES:

Chagas disease; cardiomyopathy; connexin 43; arrhythmias

PÁGINAS: 55
GRANDE ÁREA: Ciências Biológicas
ÁREA: Biologia Geral
RESUMO:

INTRODUCTION: Chronic chagasic cardiomyopathy is a debilitating disease of fatal course, with cardiac arrhythmias being the main cause of sudden death in individuals with this disease. Due to the lack of adequate therapeutic options, the understanding of the mechanisms that lead to the development of severe arrhythmias is of great relevance. Connexin 43 is an important protein component of the communicating junctions in cardiomyocytes, and the altered expression of this protein is related to conduction disorders in other cardiomyopathies. OBJECTIVE: To characterize the changes in expression and distribution of Cx43 in chronic chagasic hearts. MATERIAL AND METHODS: C57BL/6 mice with 6 and 12 months of infection by the Colombian Trypanosoma cruzi strain and uninfected controls were submitted to functional evaluation (ergometric and ECG). After euthanasia, the hearts were collected and destined for histopathological analysis, to evaluate the inflammatory infiltrate and fibrosis; analysis by immunofluorescence to evaluate the distribution pattern of total and phosphorylated Cx43 (S368); analysis by the Immunogold technique, to evaluate the presence of Cx43 in the intercalated discs; gene expression analysis by RT-qPCR, to evaluate the gene expression of total Cx43, TNF-α and IL-1β. Samples from explanted hearts of patients with chronic chagasic cardiomyopathy submitted to cardiac transplantation were used for immunofluorescence analysis of Cx43 expression. RESULTS: Animals with 6 and 12 months of infection lost the ability to exercise on the treadmill and presented conduction disorders in the heart, observed on the ECG. Histopathological analyzes confirmed intense inflammatory and fibrotic infiltration in chagasic hearts (6 and 12 months), different from that observed in control animals. In the immunofluorescence analyses, we observed a change in the total Cx43 distribution and with lateral membrane or cardiomyocyte markings in the infected animals (6 and 12 months), while the hearts of uninfected animals presented Cx43 located in the intercalated discs. The staining for Cx43 (S368) was more intense in infected (6 and 12 months) than in uninfected animals. In the analysis by Immunogold, uninfected animals presented more intense localization of total Cx43 in the intercalated discs, whereas in the infected ones the markings were present in structures similar to autophagic vacuoles. The RT-qPCR analyses showed an increase in the gene expression of TNF-α and IL-1β in the infected (6 and 12 months) compared to uninfected controls. A reduction of Cx43 gene expression was reduced in the animals with 6 months, but not witl 12 months of infection, compared to uninfected controls. Finally, the labeling of total Cx43 and Cx43 (S368) in the human material presented a pattern similar to that observed in the experimental model. CONCLUSION: Chronic chagasic hearts present alterations in Cx43 expression, as well as in the distribution pattern of total and phosphorylated Cx43, which may be associated with the high production of proinflammatory cytokines TNF-α and IL-1β, and contribute to the establishment of conduction disorders in Chagas disease.

MEMBROS DA BANCA:
Interno - 285360 - LUIZ ANTONIO RODRIGUES DE FREITAS
Externo à Instituição - MARIA FERNANDA RIOS GRASSI - Fiocruz-Ba
Presidente - 012.993.637-50 - MILENA BOTELHO PEREIRA SOARES - UFRJ
Interno - 028.288.917-55 - VALÉRIA DE MATOS BORGES - UFRJ