ORIGINAL ARTICLE Fecal Microbial Transplant After Ileocolic Resection Reduces Ileitis but Restores Colitis in IL-10 2/2 Mice Troy Perry, MD, PhD,* Juan Jovel, PhD, † Jordan Patterson, MSc, † Gane Wong, PhD, †,‡ ,§ Richard N. Fedorak, MD, † Aducio Thiesen, MD, PhD, k Bryan Dicken, MD,* and Karen L. Madsen, PhD † Background: Ileocolic resection (ICR) is frequently performed for Crohn’s disease; however, disease commonly recurs early in the neoterminal ileum. The aim of this study was to use the IL-10 2/2 mouse to determine the effects of ICR on gut microbiome and immune function and if postoperative fecal microbial transplant (FMT) would improve disease. Methods: ICR was performed in 129S1/SvlmJ IL10 2/2 mice followed by FMT using stool from wild-type mice. Sham-transplant mice received their own stool. Stool samples were collected on day 0, day 13 (after ICR), and day 27 (after FMT) for whole metagenome shot-gun sequencing. Mucosal- associated bacteria were quantified with quantitative PCR and visualized by fluorescent in situ hybridization. Tissue cytokines were measured with multiplex arrays and mononuclear phagocyte populations by flow cytometry. Results: Surgery induced microbial functional and taxonomic shifts, decreased diversity, and depleted Bacteroidia and Clostridia. ICR mice had reduced colitis but worse ileitis with bacterial overgrowth, increased translocation, and reduction in tissue macrophages. FMT prevented ileitis but restored colitis and allowed for a bloom of g-proteobacteria. In the colon, ICR and sham transplant were associated with recruitment of tolerogenic dendritic cells, whereas FMT shifted these immune cell subsets to control profiles along with increasing cytokine levels. Conclusions: This study suggests that surgical-induced immune dysfunction and microbial dysbiosis with impaired clearance may be the underlying cause of the early ulcerations found in the ileum of patients with Crohn’s disease after ICR. FMT has an immunostimulatory effect on the postoperative intestine, which was beneficial in preventing ileitis, but detrimental in restoring colonic injury after surgery. (Inflamm Bowel Dis 2015;21:1479–1490) Key Words: colitis, dysbiosis, metagenome, dendritic cells, Crohn’s disease S urgery remains a necessary treatment for most patients with Crohn’s disease (CD), with resection of the ileocecal region (ICR) being most common. 1 However, rapid recurrence at the anastomosis commonly occurs, and it is believed that recurrence is due to loss of the ileocecal valve, thereby introducing colonic bacteria into the ileum. 2 Studies in humans and animal models have highlighted the interaction of the gut immune system with its microbial inhabitants as central to CD pathogenesis, 3 but little work has been performed to study this relationship in postoperative disease. Mononuclear phagocytes (MPs) including macrophages (MF) and dendritic cells (DCs) are found in large numbers in the gut lamina propria (LP). 4 Under steady-state conditions, intes- tinal macrophages clear antigens without evoking inflammatory responses whereas DCs promote tolerance by trafficking antigen to mesenteric lymph nodes and inducing T regulatory cells. 5,6 After surgery, MP subsets undergo significant perturbations because of their recruitment and role in tissue repair and wound healing. 7 IL-10 gene-deficient (IL-10 2/2 ) mice spontaneously develop a patchy chronic inflammation primarily in the ileum, cecum, and colon shortly after weaning. 8,9 The development of colitis in this model is highly dependent on the environment, especially the composition of the gut microbiota, and treatment aimed at modulating the colonic microbiota has shown bene- fit. 10,11 Recently, a surgical resection model was defined in IL-10 2/2 mice, whereby a severe ileitis developed after ICR, mimicking the human condition. 12 In this study, we further refined this model of ileocecal resection in IL-10 2/2 mice analogous to the procedure commonly performed for ileocecal CD in humans and performed a metagenomic analysis of microbial changes related to surgery. As well, we performed a fecal microbial trans- plant (FMT) after ICR using stool from healthy wild-type donor animals to attempt to restore microbial diversity and composition. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.ibdjournal.org). Received for publication November 5, 2014; Accepted February 3, 2015. From the Departments of *Surgery, † Medicine and ‡ Biological Sciences, Uni- versity of Alberta, Edmonton, AB, Canada; § BGI-Shenzhen, Shenzhen, China; and k Department of Laboratory Medicine, University of Alberta, Edmonton, AB, Canada. Supported by Canadian Institutes for Health Research, Alberta Innovates, Alberta IBD Consortium, Canadian Surgical Research Fund, the Edmonton Civic Employees Research Assistance Fund, Alberta Innovates Technology, and Centers of Research Excellence (I-Core). The authors have no conflicts of interest to disclose. Reprints: Karen L. Madsen, PhD, Department of Medicine, University of Alberta, 7-142K Katz Building, Edmonton, AB, Canada T6G 2E1 (e-mail: karen.madsen@ualberta.ca). Copyright © 2015 Crohn’s & Colitis Foundation of America, Inc. DOI 10.1097/MIB.0000000000000383 Published online 19 May 2015. Inflamm Bowel Dis  Volume 21, Number 7, July 2015 www.ibdjournal.org | 1479 Copyright © 2015 Crohn’s & Colitis Foundation of America, Inc. Unauthorized reproduction of this article is prohibited.