Involvement of lipid microdomains in human endothelial cells infected by Streptococcus agalactiae type III belonging to the hypervirulent ST-17

Abstract

BACKGROUND Streptococcus agalactiae capsular type III strains are a leading cause of invasive neonatal infections. Many pathogens have developed mechanisms to escape from host defense response using the host membrane microdomain machinery. Lipid rafts play an important role in a variety of cellular functions and the benefit provided by interaction with lipid rafts can vary from one pathogen to another. OBJECTIVES This study aims to evaluate the involvement of membrane microdomains during infection of human endothelial cell by S. agalactiae. METHODS The effects of cholesterol depletion and PI3K/AKT signaling pathway activation during S. agalactiae-human umbilical vein endothelial cells (HUVEC) interaction were analysed by pre-treatment with methyl-β-cyclodextrin (MβCD) or LY294002 inhibitors, immunofluorescence and immunoblot analysis. The involvement of lipid rafts was analysed by colocalisation of bacteria with flotillin-1 and caveolin-1 using fluorescence confocal microscopy. FINDINGSIn this work, we demonstrated the importance of the integrity of lipid rafts microdomains and activation of PI3K/Akt pathway during invasion of S. agalactiae strain to HUVEC cells. Our results suggest the involvement of flotillin-1 and caveolin-1 during the invasion of S. agalactiae strain in HUVEC cells.CONCLUSIONS The collection of our results suggests that lipid microdomain affects the interaction of S. agalactiae type III belonging to the hypervirulent ST-17 with HUVEC cells through PI3K/Akt signaling pathway.Key words: S. agalactiae -lipid rafts -flotillin-1 -caveolin-1 -HUVEC -PI3K/Akt pathway Streptococcus agalactiae is a leading cause of neonatal infections, such as meningitis, sepsis and pneumonia. (1) In particular, S. agalactiae capsular type III strains belonging to the hypervirulent clonal complex 17 have been significantly associated with meningitis and account for up to 44 early onset disease and 67% late onset disease cases compared with less than 10% of colonising isolates. (2,3) Microorganisms interact with host cell lipid rafts microdomains to enter and survive inside the cell. (4) Lipid rafts play an important role in a variety of cellular functions, including polarisation, signal transduction, endocytosis, secretion, cell-cell and cell-pathogen adhesion. Several pathogens, such as viruses, bacteria and protozoa, can use the host-cell lipid rafts to secure their entrance and maintenance inside target cells. The benefit provided by interaction with lipid rafts can vary from one pathogen to another. (5) Lipid rafts are considered as dynamic assemblies of cholesterol and sphingolipids in

Egg White-Derived Peptides QVPLW and LCAY Inhibit the Activity of Angiotensin I-Converting Enzyme in Human Umbilical Vein Endothelial Cells by Suppressing Its Recruitment into Lipid Rafts

“…In this study, MβCD was used to study the correlation between ACE and lipid rafts. MβCD is a concentration-dependent reagent that could extract cholesterol in lipid rafts and perturb the stability and function of lipid rafts; thus, it is widely used to study the function of lipid rafts. For example, MβCD was used as an inhibitor of lipid rafts to study whether lipid rafts play a key role for α-hemolysin in mediating the detrimental effect on bone formation .…”

“…23,24 Methyl-βcyclodextrin (MβCD) is widely used for evaluating the relationship between lipid rafts and membrane proteins as it depletes cholesterol in lipid rafts and perturbs the stability and functions of lipid rafts. 25 Here, MβCD was used to study the correlation between the activities of ACE and lipid rafts. Furthermore, we identified eight novel peptides from egg white protein and evaluated their ACE activity regulatory effects in HUVECs.…”

“…The methods currently used to study the association between membrane proteins and lipid rafts are largely based on the isolation of lipid rafts and the use of immunoblotting tools combined with confocal microscopic imaging, which enables the evaluation and verification of protein localization in the cell membrane in a multifaceted manner. , Methyl-β-cyclodextrin (MβCD) is widely used for evaluating the relationship between lipid rafts and membrane proteins as it depletes cholesterol in lipid rafts and perturbs the stability and functions of lipid rafts . Here, MβCD was used to study the correlation between the activities of ACE and lipid rafts.…”

Role of Caveolin-1 in Sepsis – A Mini-Review

“…The research aims to improve the understanding of pathophysiological pathways that control cell barrier dysfunction and increased vascular permeability to implement new therapeutic strategies for the treatment of sepsis. Furthermore, modifying microfilaments dynamics in human endothelial cells could be na important tool for the development of treatment options for sepsis (73). Currently, sepsis treatment does not address the underlying molecular pathogenesis, but only attempts to reduce the harmful consequences of sepsis.…”

“…Cav-1 had a significant protective role in sepsis and endotoxemia (74). However, most experimental assays have used cholesterolsequestering drugs that do not distinguish caveolae from other molecules that form lipid rafts (1,2,73,74). In this way, more specific analyzes such as overexpression, small interfering RNA (siRNA) and knockout (KO) animals can provide more accurate results.…”