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Background & Aims: As more treatment options for inflammatory bowel diseases become available, it is important to identify patients most likely to respond to different therapies. We created and validated a scoring system to identify patients with Crohn's disease (CD) who respond to vedolizumab., Methods: We collected data from the GEMINI 2 phase 3 trial of patients with active CD treated with vedolizumab for 26 weeks (n = 814) and performed logistic regression analysis to identify factors associated with clinical, steroid-free, and durable remission (derivation set). We used these data to develop a clinical decision support tool, which we validated using data from 366 participants in a separate clinical practice observational cohort of patients with active CD treated with vedolizumab for 26 weeks (the VICTORY cohort). We evaluated the ability of this tool to identify patients in clinical remission or corticosteroid-free remission, or those with mucosal healing (MH), clinical remission with MH, or corticosteroid-free remission with MH after vedolizumab therapy using receiver operating characteristic area under the curve (AUC) analyses. The primary outcome was to develop and validate a list of factors associated with achieving remission by vedolizumab in patients with active CD., Results: In the derivation analysis, we identified absence of previous treatment with a tumor necrosis factor antagonist (+3 points), absence of prior bowel surgery (+2 points), absence of prior fistulizing disease (+2 points), baseline level of albumin (+0.4 points per g/L), and baseline concentration of C-reactive protein (reduction of 0.5 points for values between 3.0 and 10.0 mg/L and 3.0 points for values >10.0 mg/L) as factors associated with remission. In the validation set, our model identified patients in clinical remission with an AUC of 0.67, patients in corticosteroid-free remission with an AUC of 0.66, patients with MH with an AUC of 0.72, patients in clinical remission with MH with an AUC of 0.73, and patients in corticosteroid-free clinical remission with MH with an AUC of 0.75. A cutoff value of 13 points identified patients in clinical remission after vedolizumab therapy with 92% sensitivity, patients in corticosteroid-free remission with 94% sensitivity, patients with MH with 98% sensitivity, patients with clinical remission and MH with 100% sensitivity, and patients with corticosteroid-free clinical remission with MH with 100% sensitivity., Conclusions: We developed and validated a scoring system to identify patients with CD most likely to respond to 26 weeks of vedolizumab therapy. Further studies are needed to optimize its accuracy in select populations and determine its cost-effectiveness., (Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Retinoic acid (RA), produced by intestinal epithelial cells (IECs) and dendritic cells (DCs) promotes the induction of regulatory T cells (Tregs) and decreases the induction of T-helper (Th)17 cells., Methods: We studied the roles of RA in mice that overproduce tumor necrosis factor (TNF) and develop chronic ileitis (TNF_ARE mice). We assessed the frequency and function of CD103+ DCs, Th17 cells, and Tregs by flow cytometry, and we measured expression of cytokines and retinaldehyde dehydrogenase (RALDH) enzymes in ileum samples, DCs, and IECs by real-time polymerase chain reaction. We quantified RA by electrochemical analysis and examined the effect of RA supplementation on TNF-induced ileitis using histologic, coculture, and suppression assays and flow cytometry., Results: Numbers of CD103+ DCs decreased in the inflamed ilea of mice with chronic disease; RA synthetic machinery (RALDH1,2) was down-regulated. Nevertheless, the proportion of CD4+, CD25+, FoxP3+ Tregs increased, indicating an alternate source for RA. IECs responded to reduced levels of RA by up-regulating RALDH3 in vivo and in vitro. Net tissue levels of RA remained lower in TNF+ARE than wild-type mice, indicating that epithelial up-regulation of RALDH3 could not maintain adequate concentrations of RA, probably because of loss of IEC mass. RA supplementation significantly attenuated disease by increasing the number and function of CD103+ DCs and Tregs and reducing Th17 cells., Conclusions: Reduced levels of RA appear to induce IECs to up-regulate synthesis of RA. RA supplementation attenuates ileitis through its effects on CD103+ DCs, Tregs, and Th17 cells. RA supplementation might offer therapeutic benefit in Crohn's disease., (Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: A balance between effector and regulatory T-cell (Treg) responses is required to maintain intestinal homeostasis. To regulate immunity, T cells migrate to the intestine using a combination of adhesion molecules and chemokine receptors. However, it is not known whether the migration pathways of effector cells and Tregs are distinct or shared. We sought to determine whether interaction between the chemokine receptor 9 (CCR9) and its ligand, chemokine ligand 25 (CCL25), allows effectors or Tregs to localize to chronically inflamed small intestine., Methods: By using a mouse model that develops Crohn's-like ileitis (tumor necrosis factor Δadenosine uracyl-rich element [TNFΔARE] mice) we examined the role of CCL25-CCR9 interactions for effector and Treg traffic using flow cytometry, quantitative reverse-transcription polymerase chain reaction, immunohistochemistry, immunoneutralization, and proliferation analyses., Results: In TNFΔARE mice, expression of CCL25 and the frequency of CCR9-expressing lymphocytes increased during late-stage disease. In the absence of CCR9, TNFΔARE mice developed exacerbated disease, compared with their CCR9-sufficient counterparts, which coincided with a deficiency of CD4(+)/CD25(+)/forkhead box P3(+) and CD8(+)/CD103(+) Tregs within the intestinal lamina propria and mesenteric lymph nodes. Furthermore, the CD8(+)/CCR9(+) subset decreased the proliferation of CD4(+) T cells in vitro. Administration of a monoclonal antibody against CCR9 to TNFΔARE mice exacerbated ileitis in vivo, confirming the regulatory role of CD8(+)/CCR9(+) cells., Conclusions: Signaling of the chemokine CCL25 through its receptor CCR9 induces Tregs to migrate to the intestine. These findings raise concerns about the development of reagents to disrupt this pathway for the treatment of patients with Crohn's disease., (Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Lymphocyte recruitment to sites of inflammation requires the sequential engagement of adhesion molecules and chemokine receptors. In the current studies we analyzed the role of CD44 for the development of chronic small-intestinal inflammatory infiltrates in vivo., Methods: By using a tumor necrosis factor (TNF)-driven model of chronic ileitis (ie, B6.129P-TNF(DeltaAU-rich element [ARE])) that recapitulates many features of Crohn's disease, we noticed dynamic changes in the expression and functional state of CD44 and its ligand hyaluronan via enzyme-linked immunosorbent assay, real-time reverse-transcription polymerase chain reaction, immunohistochemistry, and flow cytometry. In addition, we assessed the role of lymphocyte populations during induction of ileitis through adoptive transfer studies, and generated CD44-deficient TNFDeltaARE mice to assess the role of CD44 for development of ileitis., Results: Soluble hyaluronan levels and expression of hyaluronan synthase-1 were increased in TNFDeltaARE mice. This coincided with increased expression of CD44 (including variant 7) and reactivity towards hyaluronan on CD4(+) T cells. CD44 was spatially colocalized with the gut-homing integrin alpha(4)beta(7), spatially linking lymphocyte rolling with arrest. These cells had an effector phenotype because they lacked L-selectin and a higher proportion in diseased mice produced TNF and interleukin-2 compared with wild-type littermates. Lastly, CD4(+) but not CD8(+) T cells conferred ileitis to RAG(-/-) recipients and deficiency of one or both alleles of the CD44 gene resulted in attenuation of the severity of ileitis in TNFDeltaARE mice., Conclusions: Our findings support an important role of CD44 expressed by CD4(+) and CD8(+) for development of ileitis mediated by TNF overproduction.

Background & Aims: CCL25 mediates the homeostatic recruitment of CCR9-expressing lymphocytes to the small intestine, but the function of this chemokine/receptor pair during chronic small intestinal inflammation has yet to be determined. Furthermore, although clinical trials to evaluate the efficacy of targeting the CCL25/CCR9 axis for the treatment of Crohn's disease are being conducted, preclinical data in animal models of IBD are lacking., Methods: In the current studies, we investigated the expression of CCL25 and CCR9 as a function of disease progression in a spontaneous murine model of chronic ileitis (SAMP1/YitFc) using flow cytometry, real-time reverse-transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and immunohistochemistry. In addition, we assessed the functional role of the axis in the overall disease process through therapeutic studies that target the chemokine or the receptor during early and late disease., Results: The percentage of CCR9-expressing lymphocytes increased during early disease, accompanied by the appearance of a population of CCR9(high) lymphocytes, predominantly within CD8(+) T cells. Yet different from patients with primary sclerosing cholangitis, the expression of CCL25 remained restricted to the small intestine, even in mice with inflammation of the biliary tree. Neutralization of the receptor or the chemokine attenuated early disease but showed no therapeutic efficacy during the later stages, when overall CCR9 expression decreased and the CCR9(high) population was absent., Conclusions: Our studies show that the role of this chemokine axis is not limited to homeostatic recruitment, as previously believed. However, these molecules appear to play their most crucial role during the early stages of chronic murine ileitis.

Background & Aims: Inflammatory bowel disease (IBD) is the second most common chronic inflammatory disorder worldwide; however, a noninvasive means of accurately assessing the severity and extent of intestinal inflammation is currently not available. The aim of the present study was to develop a noninvasive imaging modality to detect and evaluate ileitis in SAMP1/YitFc (SAMP) mice., Methods: An image-enhancing ultrasound (US) contrast agent, consisting of encapsulated gaseous microbubbles (MB), was developed specifically to bind mucosal addressin cellular adhesion molecule-1 (MAdCAM-1), a mucosal-restricted addressin up-regulated during gut inflammation. MAdCAM-1-targeted MB (MB(M)) were tested for binding specificity on MAdCAM-1 protein and tumor necrosis factor (TNF)-stimulated SVEC4-10 endothelial cells using an in vitro flow chamber assay and for their ability to detect and quantify ileitis by intravital microscopy and transabdominal US., Results: Under in vitro flow conditions, a 100-fold increase in MB(M) binding was observed on MAdCAM-1 protein compared with nonspecific MB (P < .001). TNF-stimulated endothelial cells bound significantly more MB(M) vs nonspecific MB (P < .001), which was abrogated after preincubation with anti-MAdCAM-1 antibodies (P < .001). In vivo, MB(M) specifically accumulated in focal areas of ileal inflammation and produced stronger acoustic echoes, measured by average video intensity, in SAMP vs uninflamed AKR mice (P < .001) or SAMP given nonspecific MB (P < .001). MB(M)-specific video intensity showed a strong positive correlation with total ileal inflammatory scores (R2 = 0.92)., Conclusions: We have developed a novel intravascular US contrast agent targeting MAdCAM-1 that specifically detects and quantifies intestinal inflammation in experimental ileitis, providing the potential for a reliable, noninvasive means to diagnose and monitor disease in patients with IBD.

Background & Aims: Adenosine has been implicated as an important regulator of the inflammatory response. Four subtypes of adenosine receptors (A 1 , A 2A , A 2B , and A 3 ) have been described, of which A 2A potentially inhibits inflammation. The aim of this study was to investigate the role of A 2A in mucosal inflammation by administering a selective A 2A agonist (ATL-146e) to experimental models of inflammatory bowel disease., Methods: The anti-inflammatory effects of ATL-146e were studied in the acute and chronic rabbit formalin-immune complex models of colitis and the SAMP1/YitFc mouse model of spontaneous ileitis., Results: ATL-146e significantly reduced the acute inflammatory index and tissue necrosis compared with vehicle ( P < .01) in the acute model of rabbit immune colitis. In the chronic rabbit immune colitis model, ATL-146e significantly suppressed inflammatory cell infiltration into the colonic mucosa ( P < .05) and prevented mortality. The administration of ATL-146e significantly decreased the chronic inflammatory index ( P < .01) and villus distortion index ( P < .01) in the ileum of SAMP1/YitFc mice, and ameliorated adoptively transferred ileitis in severe combined immunodeficient mice injected with CD4 + T cells from SAMP1/Yit mice ( P < .05). Tumor necrosis factor, interferon gamma, and interleukin 4 concentrations were significantly suppressed by ATL-146e treatment in supernatants from cultures of mesenteric lymph node cells of SAMP1/YitFc mice ( P < .05 vs vehicle-treated mice)., Conclusions: A 2A adenosine receptor activation by ATL-146e significantly reduced inflammation in the intestinal mucosa. This effect was associated with decreased leukocyte infiltration and inhibition of proinflammatory cytokines. Activation of A 2A by selective agonism may therefore serve as a novel therapy for the treatment of inflammatory bowel disease.

Background & Aims: SAMP1/Yit mice spontaneously develop chronic terminal ileitis, reminiscent of the human disease described by Crohn et al. in 1932. Several new phenotypic features have appeared in our colony after more than 20 generations of brother-sister mating. In this report, we describe the distinguishing features of the SAMP1/YitFc substrain at the University of Virginia, compared with the Japanese SAMP1/Yit parental strain., Methods: A colony of SAMP1/Yit mice was established at the University of Virginia in 1996, from 2 breeding pairs obtained from Japan. A systematic characterization of their phenotypic and immunologic characteristics was performed at 4, 10, 40, and more than 60 weeks of age., Results: The following differences were observed: (1) SAMP1/YitFc mice displayed established ileitis as early as 10 weeks of age, (2) the incidence of skin lesions inversely correlated with the occurrence of intestinal inflammation, (3) mice develop chronic ileitis with prominent muscular hypertrophy and focal collagen deposition in inflamed segments, (4) mesenteric lymph node lymphocytes acquired an activated phenotype coincident with disease progression, (5) high interferon-gamma production was detected by 4 weeks of age and preceded the onset of ileitis, and (6) a subgroup of mice (approximately 5%) developed perianal disease with ulceration and fistulae., Conclusions: The SAMP1/YitFc substrain exhibits unique characteristics when compared with the original Japanese strain. Of particular interest is the emergence of perianal fistulizing disease, to our knowledge the first report of such occurrence in an animal model of inflammatory bowel disease.