Envolvimento de microdomínios lipídicos na infecção de células endoteliais humanas por Streptococo agalactiae

Abstract

Group B streptococci (GBS) are the most common cause of pneumonia and sepsis during the neonatal period. The first step in the development of pathogenesis depends on the process of adhesion and invasion of the pathogen to the target cell. The exploration of regions known as lipid microdomains (ML) and the modulation of signaling pathways may contribute to the process of pathogen invasion. However, the mechanism by which GBS interacts with human cells and damage physiological processes is an area that needs to be better understood. The objective of this study was to investigate the adhesion and intracellular viability of GBS belonging to serotype III in human endothelial cells. GBS 90356 strain (capsular type III-CSF) exhibited a reduction in adhesion and invasion in MβCD-treated endothelial cells. In contrast, an expressive increase in adhesion and decrease of invasion were verified in HUVEC treated with PI3K inhibitor (LY294002). The results showed the presence of the major ML marker molecules (Cav-1, Cav-2, Flot-1 and Flot-2) on HUVEC. Our data addresses for the first time the co-localization of GBS with Cav-1, Cav-2 and Flot-1 on HUVEC by confocal laser microscopic analysis. In addition, western blotting assays of showed the involvement of the PI3K/AKT pathway during the interaction GBS-HUVEC after 15 min post-infection. The modulation at the levels of sphingosine-1 phosphate during the interaction of GBS with HUVEC was also demonstrated by liquid chromatography. This work provides the evidence that lipid rafts and raft-associated PI3K are implicated in GBS invasion to human endothelial cells.