Evaluating S. flexneri pathogenesis in the human enteroid model.

The enteric pathogen, Shigella , is one of the leading causes of moderate-to-severe diarrhea and death in young children in developing countries. Transformed cell lines and animal models have been widely used to study Shigella pathogenesis. In addition to altered physiology, transformed cell lines are composed of a single cell type that does not sufficiently represent the complex multi-cellular environment of the human colon. Most available animal models do not accurately mimic human disease. The human intestinal enteroid model, derived from LGR5+ stem cell-containing intestinal crypts from healthy subjects represents a technological leap in human gastrointestinal system modeling and provides a more physiologically relevant system that includes multiple cell types and features of the human intestine. We established the utility of this model for studying basic aspects of Shigella pathogenesis and host responses. In this study, we show that S. flexneri is capable of infecting and replicating intracellularly in human enteroids derived from different segments of the intestine. Apical invasion by S. flexneri is very limited but increases ∼10-fold when enteroids are differentiated to include M cells. Invasion via the basolateral surface was at least 2-log10 more efficient than apical infection. Increased secretion of Interleukin-8 and higher expression of the mucin glycoprotein Muc2 was observed in the enteroids following S. flexneri infection. The human enteroid model promises to bridge some of the gaps between traditional cell culture, animal models and human infection.