Shigella flexneri Adherence Factor Expression in In Vivo -Like Conditions

Abstract

Bacterial pathogens have evolved to regulate virulence gene expression at critical points in the colonization and infection processes to successfully cause disease. The Shigella species infect the epithelial cells lining the colon to result in millions of cases of diarrhea and a significant global health burden. As antibiotic resistance rates increase, understanding the mechanisms of infection is vital to ensure successful vaccine development. Despite significant gains in our understanding of Shigella infection, it remains unknown how the bacteria initiate contact with the colonic epithelium. Most pathogens harbor multiple adherence factors to facilitate this process, but Shigella was thought to have lost the ability to produce these factors. Interestingly, we have identified conditions that mimic some features of gastrointestinal transit and that enable Shigella to express adherence structural genes. This work highlights aspects of genetic regulation for Shigella adherence factors and may have a significant impact on future vaccine development.

A versatile human intestinal organoid-derived epithelial monolayer model for the study of enteric pathogens

“…For Shigella ( Figure 4 and Supplemental Figure S2 ), adherence was highest in the cecum and colon, with the rates of both comparable to adherence rates with polarized T84 cells (26). Apical surface adherence was facilitated by Shigella adherence factors expressed in the in vivo-like culture conditions, and replicates previous analyses with both the colon and cecum models (23, 24, 26). Meanwhile, Shigella invasion was the highest in colon following treatment with RANKL to induce the presence of M cells.…”

“…To validate the site of Shigella infection, we analyzed wild type S. flexneri strain 2457T infection in the terminal ileum, cecum, and colon-derived HIODEM by assaying for adherence and invasion. Prior to infection, S. flexneri was cultured in a combination of bile salts and glucose to replicate small intestinal transit (24-26). For adherence, approximately 5% of the bacterial inoculum adhered to ileum-derived HIODEM, while the adherence rates for cecum and colon-derived HIODEM models were nearly triple (~12-15%; Figure 4A ).…”

“…Organoid-derived epithelial monolayer models like the HIODEM have enabled infection analyses by providing a process by which pathogens can directly interact with the apical side of the epithelium (11, 24, 33, 54-58). While three-dimensional organoid systems are available (40, 59-63) and “apical-out” organoid systems have been developed (64), HIODEM and other 2-D systems offer easily accessible monolayers for pathogenesis studies in which apical and basolateral cytokine secretion profiles and changes in TEER can be examined in a standard transwell culture setting.…”

Research in a time of enteroids and organoids: how the human gut model has transformed the study of enteric bacterial pathogens

“…The authors used colonoids to show that these adherence structures on the bacteria were important for their initial attachment to the epithelial surface. 24…”

Enteropathogenic Infections: Organoids Go Bacterial

“…initiates the production of an adhesive biofilm induced by prolonged exposure to bile salts and glucose during small intestinal passage. Adherence analysis in human colon-derived organoids infected with Shigella flexneri ( S. flexneri ) revealed the emergence of adhesive structures contacting the host epithelial cell [ 43 ]. Basic characteristics of host cell infection with S. flexneri were captured in an organoid-derived monolayer model originating from different sections of the human intestine [ 44 ].…”