Intestinal cell migration damage induced by enteropathogenic Escherichia coli strains

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.

Virulence-Related Genes and Coenteropathogens Associated with Clinical Outcomes of Enteropathogenic Escherichia coli Infections in Children from the Brazilian Semiarid Region: a Case-Control Study of Diarrhea

“…Our data support the importance of discriminating tEPEC and aEPEC infections, as the related outcomes can be highly different (6,34). Attempts to identify specific EPEC genetic markers that could predict severe outcomes of infection were described in the past (4,12,14,35). Here, we employed an unprecedented mPCR panel covering 18 different EPEC virulence strategies, including LEE-and non-LEE-encoded effectors: proteases, chaperones, regulators, and other type 3 secretion system (T3SS) components.…”

“…The genetic diversity of EPEC strains has been highlighted (10)(11)(12)(13), and further studies showed that specific EPEC VRGs may be associated with different clinical outcomes (4,12,14,15). In this study, we aimed to characterize the EPEC virulencerelated gene (VRG) distribution and the copathogens associated with diarrhea and nutrition-related outcomes in children aged 2 to 36 months.…”