Intestinal cell migration damage induced by enteropathogenic Escherichia coli strains.

P.A Cavalcante,I.F.N Lima,M.A.V Reyes,M.D Bona,T.S Rodrigues,P.H.Q.S Medeiros,M.S.M.G Amaral,M.M.G Prata,H.N Veras,A Havt,A.V Alves Da Silva,A.K.S Santos,A.A.M Lima,F.A.P Rodrigues,S.A Ribeiro,J.S Quetz

doi:10.1590/1414-431x20187423

Abstract

Epithelial cell migration is an essential response to enteric pathogens such as enteropathogenic Escherichia coli (EPEC). This study aimed to investigate the effects of EPEC infection on intestinal epithelial cell migration in vitro, as well as the involvement of type III secretion system (T3SS) and Rho GTPases. Crypt intestinal epithelial cells (IEC-6) were infected with EPEC strains (E2348/69, ΔescF, and the LDI001 strain isolated from a malnourished Brazilian child) and commensal E. coli HS. Wound migration and cell death assays were performed at different time-points. Transcription and expression of Rho GTPases were evaluated using real-time PCR and western blotting. Overall, EPEC E2348/69 reduced migration and increased apoptosis and necrosis levels compared to EPEC LDI001 and E. coli HS strains. Moreover, EPEC LDI001 impaired cell migration at a higher level than E. coli HS and increased necrosis after 24 hours compared to the control group. The different profiles of virulence genes between the two wild-type EPEC strains, characterized by the absence of espL and nleE genes in the LDI001, might explain the phenotypic results, playing significant roles on cell migration impairment and cell death-related events. Moreover, the type III secretion system is determinant for the inhibition of intestinal epithelial cell migration by EPEC 2348/69, as its deletion prevented the effect. Active Rac1 concentrations were increased in E2348/69 and LDI001-infected cells, while the T3SS-deficient strain did not demonstrate this activation. This study contributes with valuable insight to characterize the mechanisms involved in the impairment of intestinal cell migration induced by EPEC.

Highlights

Enteropathogenic Escherichia coli (EPEC) was recently associated with higher risk of infant death in a multicenter case-control study on diarrhea in developing countries [1]
These detrimental effects occur by interactions of host cell molecules with effector proteins injected by EPEC into the epithelium through a type III secretion system (T3SS) [4]
We aimed to investigate the intestinal cell migration impairment caused by two different EPEC

Summary

Introduction

Enteropathogenic Escherichia coli (EPEC) was recently associated with higher risk of infant death in a multicenter case-control study on diarrhea in developing countries [1]. The central mechanism of EPEC pathogenesis is a lesion characterized by attaching and effacing (A/E) and reorganization of the actin cytoskeleton of host cells, causing the destruction of intestinal microvilli [4]. EPEC has been associated with altered intestinal arrier function, including reduction of intestinal surface area and redistribution of tight junctions [5,6]. These detrimental effects occur by interactions of host cell molecules with effector proteins injected by EPEC into the epithelium through a type III secretion system (T3SS) [4]. Pathogenesis of damage due to EPEC is not well characterized [7]

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