The intestinal epithelium serves to absorb nutrients, salts and water from the intestinal lumen, but at the same provide a first barrier against harmful microorganisms. To overcome this barrier, invasive enterobacteria, such as Salmonella Typhimurium, have developed virulence factors to approach the epithelium by flagellar motility, bind to the apical surface, and force their way into the intracellular environment. The molecular mechanisms explaining this critical bacterium – host cell interplay have traditionally been studied using cell line models that poorly mimic the features of mammalian gut tissue. However, the development of 2- and 3-dimensional enteroids and colonoid from adult stem cells has ushered in a new era, where we now can study the stepwise progression of invasive bacterial disease under conditions that more faithfully recapitulate key aspects of gut epithelial organization and physiology.
The SurfEx project is based on our recently developed technology to grow human intestinal epithelia from enteroids and colonoids within chambers that permit live-cell imaging of infection dynamics at unprecedented temporal and spatial resolution (van Rijn & Eriksson et al 2022; DOI: https://doi.org/10.1128/mbio.00022-22; see Figure). By combining such live-cell microscopy with molecular biology and genetic tools, the project will dissect how the composition and structure of the epithelial cell surface affects epithelial barrier properties, and how the interplay between Salmonella virulence factors and epithelial surface features determines whether the attack results in failed or successful bacterial breaching of the epithelial lining.
Specific objectives
- To advance our human enteroid and colonoid models for live-cell imaging of enterobacterial attack on the human intestinal epithelial surface.
- To explain how the molecular composition of the apical epithelial cell surface and its glycocalyx affects the strength of the epithelial barrier against Salmonella attack.
- To assess how specific Salmonella virulence factors (i.e. flagella, adhesins, secreted effectors) affect whether the bacteria fail or succeed in breaching the epithelial barrier.
