Banca de DEFESA: ANA GLÓRIA BARBOSA BEZERRA DE SOUSA LIMA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ANA GLÓRIA BARBOSA BEZERRA DE SOUSA LIMA
DATA : 26/02/2018
HORA: 09:00
LOCAL: Auditório do Museu de Ciências Morfológicas - CB/UFRN
TÍTULO:

Plasmodium falciparum PROTEIN EXTRACTS INDUCE HEMOLYSIS OF HUMAN ERYTHROCYTES VIA COMPLEMENT SYSTEM

PALAVRAS-CHAVES:

Plasmodium falciparum; malaria; complement system; immunopathogenesis; hemolysis.

PÁGINAS: 65
GRANDE ÁREA: Ciências Biológicas
ÁREA: Parasitologia
RESUMO:

Most cases of severe human malaria are attributed to Plasmodium falciparum infections, considered the most aggressive due to tissue hypoxia resulting from several factors, including severe anemia. In this sense, this study evaluated the degree of hemolysis mediated by the complement system in human erythrocytes sensitized with protein extracts of P. falciparum through in vitro autologous hemolytic assays in order to establish relationships between this activity and its implications for the pathogenesis of complicated malaria. Erythrocytes treated with EBPf with the minimum concentration of 0.06 μg/ml were hemolyzed in about 60% when in the presence of the complement; whereas in the absence, the effect was reduced to less than 20%, indicating it’s participation. In cells donor with sickle cell trait (HbAS), there was a small reduction in hemolysis compared to normal red blood cells, suggesting a differential immunoreactivity in this case. In contrast to the treatment with neuraminidase, the hemolytic action profiles were similar to those obtained with EBPf, indicating that P. falciparum probably has proteases with a similar action to this enzyme, cleaving proteins sialisated on the surface of the target cell, using invasion alternatives pathways under certain conditions. The SDS-PAGE gel stained with silver nitrate revealed an equivalent protein degradation profile between erythrocyte treatments with EBPf and neuraminidase, reinforcing this hypothesis. In addition, parasite’s proteases may be able to degrade erythrocyte surface protein structures such as glycophorin A, while others are preserved, such as aquaporin 1, and may contribute to the immunopathogenesis of the disease. The dose-response assay demonstrated a reduction in hemolytic activity only at the concentration of 0.03 μg / mL, indicating that the high parasitemia is not a strictly crucial factor for complement activation, probably due to a potentiated biological phenomenon by other factors involved in the infectious process. Thus, we concluded that P. falciparum protein extract induce hemolysis in human erythrocytes via complement, being this one of the mechanisms responsible for the generation of an exacerbated inflammatory process and loss of the individual’s homeostasis.

MEMBROS DA BANCA:
Presidente - 2213126 - VALTER FERREIRA DE ANDRADE NETO
Externo ao Programa - 2275890 - MARCELO DE SOUSA DA SILVA
Externo à Instituição - VALESKA SANTANA DE SENA PEREIRA - F.M.Nassau