A versatile human intestinal organoid-derived epithelial monolayer model for the study of enteric pathogens
Authors: Nickerson Kourtney P. , Llanos-Chea Alejandro , Ingano Laura , Serena Gloria , Miranda-Ribera Alba , Perlman Meryl , Lima Rosiane , Sztein Marcelo B. , Fasano Alessio , Senger Stefania , Faherty Christina S. 
Published: November 2020

Gastrointestinal infections cause significant morbidity and mortality worldwide. The complexity of human biology and limited insights into host-specific infection mechanisms are key barriers to current therapeutic development. Here, we demonstrate that two-dimensional epithelial monolayers derived from human intestinal organoids, combined within vivo-like bacterial culturing conditions, provide significant advancements for the study of enteropathogens. Monolayers from the terminal ileum, cecum, and ascending colon recapitulated the composition of the gastrointestinal epithelium, in which several techniques were used to detect the presence of enterocytes, mucus-producing goblet cells, and other cell types following differentiation. Importantly, the addition of receptor activator of nuclear factor kappa-B ligand (RANKL) increased the presence of M cells, critical antigen-sampling cells often exploited by enteric pathogens. For infections, bacteria were grown underin vivo-like conditions known to induce virulence. Overall, interesting patterns of tissue tropism and clinical manifestations were observed.Shigella flexneriadhered efficiently to the cecum and colon; however, invasion in the colon was best following RANKL treatment. BothSalmonellaTyphi and Typhimurium serovars displayed different infection patterns, withS. Typhimurium causing more destruction of the terminal ileum andS. Typhi infecting the cecum more efficiently than the ileum, particularly with regards to adherence. Finally, various pathovars ofEscherichia colivalidated the model by confirming only adherence was observed with these strains. This work demonstrates that the combination of human-derived tissue with targeted bacterial growth conditions enables powerful analyses of human-specific infections that could lead to important insights into pathogenesis and accelerate future vaccine development.

Importance

While traditional laboratory techniques and animal models have provided valuable knowledge in discerning virulence mechanisms of enteric pathogens, the complexity of the human gastrointestinal tract has hindered our understanding of physiologically relevant, human-specific interactions; and thus, has significantly delayed successful vaccine development. The human intestinal organoid-derived epithelial monolayer (HIODEM) model closely recapitulates the diverse cell populations of the intestine, allowing for the study of human-specific infections. Differentiation conditions permit the expansion of various cell populations, including M cells that are vital to immune recognition and the establishment of infection by some bacteria. We provide details of reproducible culture methods and infection conditions for the analyses ofShigella, Salmonella, and pathogenicEscherichia coliin which tissue tropism and pathogen-specific infection patterns were detected. This system will be vital for future studies that explore infection conditions, health status, or epigenetic differences; and will serve as a novel screening platform for therapeutic development.