Browsing by Author "Shroyer, Noah F."

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    Engineering bacterial thiosulfate and tetrathionate sensors for detecting gut inflammation
    (EMBO Press, 2017) Daeffler, Kristina N-M; Galley, Jeffrey D.; Sheth, Ravi U.; Ortiz-Velez, Laura C.; Bibb, Christopher O.; Shroyer, Noah F.; Britton, Robert A.; Tabor, Jeffrey J.; Bioengineering; Biosciences
    There is a groundswell of interest in using genetically engineered sensor bacteria to study gut microbiota pathways, and diagnose or treat associated diseases. Here, we computationally identify the first biological thiosulfate sensor and an improved tetrathionate sensor, both two?component systems from marine Shewanella species, and validate them in laboratory Escherichiaﾠcoli. Then, we port these sensors into a gut?adapted probiotic E.ﾠcoli strain, and develop a method based upon oral gavage and flow cytometry of colon and fecal samples to demonstrate that colon inflammation (colitis) activates the thiosulfate sensor in mice harboring native gut microbiota. Our thiosulfate sensor may have applications in bacterial diagnostics or therapeutics. Finally, our approach can be replicated for a wide range of bacterial sensors and should thus enable a new class of minimally invasive studies of gut microbiota pathways.
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    Enteroaggregative E. coli Adherence to Human Heparan Sulfate Proteoglycans Drives Segment and Host Specific Responses to Infection
    (Public Library of Science, 2020) Rajan, Anubama; Robertson, Matthew J.; Carter, Hannah E.; Poole, Nina M.; Clark, Justin R.; Green, Sabrina I.; Criss, Zachary K.; Zhao, Boyang; Karandikar, Umesh; Xing, Yikun; Margalef-Català, Mar; Jain, Nikhil; Wilson, Reid L.; Bai, Fan; Hyser, Joseph M.; Petrosino, Joseph; Shroyer, Noah F.; Blutt, Sarah E.; Coarfa, Cristian; Song, Xuezheng; Prasad, BV Venkataram; Amieva, Manuel R.; Grande-Allen, Jane; Estes, Mary K.; Okhuysen, Pablo C.; Maresso, Anthony W.; Bioengineering
    Enteroaggregative Escherichia coli (EAEC) is a significant cause of acute and chronic diarrhea, foodborne outbreaks, infections of the immunocompromised, and growth stunting in children in developing nations. There is no vaccine and resistance to antibiotics is rising. Unlike related E. coli pathotypes that are often associated with acute bouts of infection, EAEC is associated with persistent diarrhea and subclinical long-term colonization. Several secreted virulence factors have been associated with EAEC pathogenesis and linked to disease in humans, less certain are the molecular drivers of adherence to the intestinal mucosa. We previously established human intestinal enteroids (HIEs) as a model system to study host-EAEC interactions and aggregative adherence fimbriae A (AafA) as a major driver of EAEC adherence to HIEs. Here, we report a large-scale assessment of the host response to EAEC adherence from all four segments of the intestine across at least three donor lines for five E. coli pathotypes. The data demonstrate that the host response in the duodenum is driven largely by the infecting pathotype, whereas the response in the colon diverges in a patient-specific manner. Major pathways altered in gene expression in each of the four enteroid segments differed dramatically, with responses observed for inflammation, apoptosis and an overwhelming response to different mucin genes. In particular, EAEC both associated with large mucus droplets and specific mucins at the epithelial surface, binding that was ameliorated when mucins were removed, a process dependent on AafA. Pan-screening for glycans for binding to purified AafA identified the human ligand as heparan sulfate proteoglycans (HSPGs). Removal of HSPG abrogated EAEC association with HIEs. These results may mean that the human intestine responds remarkably different to distinct pathobionts that is dependent on the both the individual and intestinal segment in question, and uncover a major role for surface heparan sulfate proteoglycans as tropism-driving factor in adherence and/or colonization.