Human Gastrointestinal Biomimetics for Enteric Bacterial Infections

Project Summary – Project 3 The intestinal mucosal surface is a complex mechano-physiologic environment comprised of pathogen, commensal, and host. Because this complexity may affect our understanding of the etiology of disease, it is critical to develop model systems that accurately capture their physiology. Human intestinal organoids (HIOs) have been proposed as a mucosal biomimetic to study infectious diseases caused by enteric pathogens. Our previously funded project (part of the NIAID U19 NAMSED initiative) established the use of HIOs to understand the pathogenesis of Enteroaggregative E. coli (EAEC), a common cause of persistent diarrhea in children, the immunocompromised, and travelers. There is no vaccine for EAEC and antibiotic treatment is complicated by multi-drug resistance, the ablation of protective commensals, and reported ineffectiveness at reducing diarrheal duration. A seminal finding from our study was the unexpected observation that the susceptibility to EAEC infection was substantially dependent on the host donor, especially in the context of new data that suggests the mucosal receptor for EAEC is heparan-sulfated proteoglycan (HSPG). The work in this renewal builds upon this observation by now hypothesizing that EAEC donor-specific adherence drives the local delivery of secreted cytopathic effectors to the intestinal epithelium. In Aim 1, a large collection of HIOs are characterized for their sensitivity to EAEC infection and hallmark signatures of molecular pathogenesis correlated to the status of donor HSPGs. In Aim 2, key intestinal mechano-physiologic properties, including luminal flow, basolateral stiffness, the presence of immune cells, and segmental connectivity, are assessed for their effect on HSPG-dependent EAEC infection. Finally, human intestinal microbiota (commensals and phage) that antagonize EAEC by competing for a glycan-based intestinal niche will be identified. This work will reveal the host factors that govern EAEC susceptibility to infection, the mechano-physiologic cues that drive them, and targeted biota-based approaches that are antagonistic and therapeutic.