Background & Aims: Loss of functional small bowel surface area causes short bowel syndrome (SBS), intestinal failure, and parenteral nutrition (PN) dependence. The gut adaptive response following resection may be difficult to predict, and it may take up to two years to determine which patients will wean from PN. Here we examined features of gut microbiota and bile acid (BA) metabolism in determining adaptation and ability to wean from PN. Methods: Stool and sera were collected from healthy controls and from SBS patients (n=52) with ileostomy, jejunostomy, ileocolonic and jejunocolonic anastomoses fed with PN plus enteral nutrition or who were exclusively enterally fed. We undertook 16S rRNA gene sequencing, BA profiling and 7α-hydroxy-4-cholesten-3-one (C4) quantitation with LC-MS/MS, and serum amino acid analyses. Results: SBS patients exhibited altered gut microbiota with reduced gut microbial diversity compared to healthy controls. We observed differences in the microbiomes of SBS patients with ileostomy vs. jejunostomy, jejunocolonic vs. ileocolonic anastomoses, and PN-dependence compared to those who weaned from PN. Stool and serum BA composition and C4 concentrations were also altered in SBS patients, reflecting adaptive changes in enterohepatic BA cycling. Stools from patients who weaned from PN were enriched in secondary BAs including deoxycholic acid and lithocholic acid. Conclusions: Shifts in gut microbiota and BA metabolites may generate a favorable luminal environment in select SBS patients, promoting the ability to wean from PN. Pro-adaptive microbial species and select BA may provide novel targets for patient-specific therapies for SBS.

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As the nation seeks to recruit and retain physician-scientists, gaps remain in understanding and addressing mitigatable challenges to the success of faculty from underrepresented minority (URM) backgrounds. The Doris Duke Charitable Foundation Fund to Retain Clinical Scientists program, implemented in 2015 at 10 academic medical centers in the United States, seeks to retain physicianscientists at risk of leaving science because of periods of extraordinary family caregiving needs, hardships that URM faculty-especially those who identify as female-are more likely to experience. At the annual Fund to Retain Clinical Scientists program directors conference in 2018, program directors-21% of whom identify as URM individuals Please see the end of this article for information about the authors.

The formation of the crypt-villus axis during gut ontogeny requires continued reciprocal interactions between the endoderm and mesenchyme. Epimorphin/syntaxin 2 (epimorphin) is a mesenchymal protein expressed in the fetal gastrointestinal tract during villus morphogenesis. To elucidate its role in gut ontogeny, the epimorphin cDNA was transfected, in sense and antisense orientations, into a rat intestinal myofibroblast cell line, MIC 216. To determine the effects of epimorphin on the epithelium, myofibroblasts were cocultured with the Caco2 cell line. Caco2 cells spread in a simple monolayer over antisense-transfected cells lacking epimorphin. In contrast, sense-transfected myofibroblasts induced Caco2 cells to form compact, round clusters with small lumens. These morphologic differences were preserved in Transwell cocultures in which cell-cell contact was prevented, suggesting that epimorphin’s effects were mediated by secreted factor(s). To determine the effects of epimorphin on crypt-villus axis formation in an in vivo model, rat gut endoderm was combined with epimorphin-transfected myofibroblasts and implanted into the chick intracoelomic cavity. The grafts in which epimorphin was overexpressed revealed multiple well-formed villi with crypt-like units, whereas those in which epimorphin expression was inhibited developed into round cystic structures without crypts or villi. Of several potential secreted morphogens, only the expression of bone morphogenetic protein 4 (Bmp4) was increased in the epimorphin-transfected cells. Incubation with noggin partially blocked the transfected myofibroblasts’ effects on Caco2 colony morphology. These results indicate that mesenchymal epimorphin has profound effects on crypt-villus morphogenesis, mediated in part by secreted factor(s) including the Bmp’s