Murine Model Of Acute Colitis Research Articles

Vitamin B12 ameliorates gut epithelial injury via modulating the HIF-1 pathway and gut microbiota

Inflammatory bowel diseases (IBDs) are immune chronic diseases characterized by recurrent episodes, resulting in continuous intestinal barrier damage and intestinal microbiota dysbiosis. Safe strategies aimed at stabilizing and reducing IBDs recurrence have been vigorously pursued. Here, we constructed a recurrent intestinal injury Drosophila model and found that vitamin B12 (VB12), an essential co-factor for organism physiological functions, could effectively protect the intestine and reduce dextran sulfate sodium-induced intestinal barrier disruption. VB12 also alleviated microbial dysbiosis in the Drosophila model and inhibited the growth of gram-negative bacteria. We demonstrated that VB12 could mitigate intestinal damage by activating the hypoxia-inducible factor-1 signaling pathway in injured conditions, which was achieved by regulating the intestinal oxidation. In addition, we also validated the protective effect of VB12 in a murine acute colitis model. In summary, we offer new insights and implications for the potential supportive role of VB12 in the management of recurrent IBDs flare-ups.

Protective Effect of Rosavin Against Intestinal Epithelial Injury in Colitis Mice and Intestinal Organoids.

Rhodiola species have been utilized as functional foods in Asia and Europe for promoting health. Research has demonstrated that Rhodiola has the potential to alleviate inflammatory bowel disease (IBD) in animal models. However, the specific active components and the underlying mechanism for ameliorating intestinal damage remain unclear. This study aims to explore the relieving effect of Rosavin (Rov), a known active constituent of Rhodiola, in IBD and the regulatory mechanisms. The therapeutic effect of Rov was evaluated using a murine model of acute colitis induced by dextran sulfate sodium salt (DSS). Inflammatory cytokines and neutrophil activation markers were measured by corresponding kits. Immunohistochemistry, immunofluorescence, TUNEL, and EdU assays were applied to investigate the tight conjunction proteins expression, epithelial marker expression, number of apoptotic cells, and epithelial proliferation, respectively. The protection effect of Rov on gut epithelial injury was assessed using TNF-α-induced intestinal organoids. Additinally, RNA sequencing was applied to observe the genetic alteration profile in these intestinal organoids. Oral administration of Rov significantly attenuated weight loss and restored colon length in mice. Notably, Rov treatment led to decreased levels of pro-inflammatory cytokines and neutrophil activation markers while increasing anti-inflammatory factors. Importantly, Rov restored intestinal despair by increasing the number of Lgr5+ stem cells, Lyz1+ Paneth cells and Muc2+ goblet cells in intestines of colitis mice, displaying reduced epithelial apoptosis and recovered barrier function. In TNF-α-induced intestinal organoids, Rov facilitated epithelial cell differentiation and protected against TNF-α-induced damage. RNA sequencing revealed upregulation in the gene expression associated with epithelial cells (including Lgr5+, Lyz1+ and Muc2+ cells) proliferation and defensin secretion, unveiling the protective mechanisms of Rov on the intestinal epithelial barrier. Rov holds potential as a natural prophylactic agent against IBD, with its protective action on the intestinal epithelium being crucial for its therapeutic efficacy.

P082 Downregulated apelin expression in T cells in the setting of Chronic Colitis

Abstract Background APJ is a G protein-coupled receptor and was originally found as an orphan receptor. Isolation of apelin (APL) from the alimentary tract was found to be the endogenous ligand for APJ. It has been reported that APL is upregulated in the colonic tissues of a murine model of acute colitis induced by dextran sodium sulfate (DSS), and thus it may be suggested to be associated with the pathogenesis of inflammatory bowel diseases (IBD) in humans. However, the mechanism and function of APL in the context of IBD are still not understood. Here, we analyzed APL expression in an animal model of chronic colitis to define its function in the pathogenesis of IBD. Methods Each cell type in the colonic tissue, including epithelial cells and lamina propria lymphocytes, were first isolated from wild type C57BL6 mice (WT) to assess APL expression. Next, naïve T cells isolated from WT were adoptively transferred into Rag deficient mice (Rag-/-) to induce chronic colitis, and then APL expression was measured either in the colonic tissue or in the isolated splenic and colonic CD4+ T cells from these T cell-reconstituted Rag-/- to compare with those of WT or Rag-/- without colitis. In addition, WT naïve T cells were differentiated into either Th1, Th2 or Th17 in vitro to analyze APL expression. Finally, the Rag-/- receiving naïve T cells were administered a synthetic APL peptide, APL-13, to assess the severity of colitis. Results Semi-quantitative PCR (qPCR) revealed that CD4+ T cells express relatively higher level of APL compared to other cell types including the epithelial cells in colonic tissue from WT. However, APL expression in the colonic tissues from the Rag-/- induced chronic colitis was unexpectedly downregulated compared to control groups without colitis; this is not consistent with the previous report using acute DSS colitis model. Subsequently, qPCR revealed significantly decreased APL expression in the splenic and colonic T cells from Rag-/- induced colitis compared to that of WT. APL expressions in the effecter T cells in vivo and all of the differentiated T cells in vitro were also significantly downregulated compared to naïve T cells and non-differentiated control T cells, respectively. Given these results, APL-13 was injected into the Rag-/- that underwent T cell reconstitution to antagonize the APL downregulation. This resulted in reduced severity of colitis compared to that of vehicle control-injected group. Conclusion These results suggest that T cells can be one of the major sources of APL in colonic tissues, and APL downregulation in effecter T cells may lead to the development of chronic colitis. In addition, this study also suggests that APL may be a novel therapeutic target for IBD.

Does caffeine have a double-edged sword role in inflammation and carcinogenesis in the colon?

Caffeine (1,3,7-trimethylxanthine, also abbreviated to CAF) is a natural chemical with stimulant effects and is commonly included in many drinks and foods, including coffee, tea, cola, energy drinks, cocoa, chocolates, and so on. Our group previously reported that oral administration of CAF efficiently suppressed the development of intestinal inflammation in a dextran sulfate sodium (DSS)-induced murine acute colitis model by suppressing the expression of chitinase 3-like 1, one of the mammalian chitinases without enzymatic activity. Chitinases are hydrolytic enzymes that break down chitin, a polymer of N-acetylglucosamine, and chitinase-like proteins have no enzymatic activity with preserving chitin-binding ability. CAF binds a cleft of the chitinase active site and plays a role as a pan-chitinase inhibitor. Although CAF showed an anti-inflammatory effect in the above model, oral administration of low-dose CAF with 10% sucrose showed potentially neoplastic effects in colonic epithelial cells in a DSS-induced murine chronic colitis model. In this review, we would like to discuss the pros and cons of coffee/CAF in colonic inflammation and neoplasia with an example of pathological finding.

Delivery of Transcriptional Factors for Activating Antioxidant Defenses against Inflammatory Bowel Disease.

Oxidative stress caused by the overproduction of reactive oxygen species (ROS) plays an important role in inflammatory bowel disease (IBD). It is well-known that the Nrf2-ARE (antioxidative response element) pathway is important in the regulation mechanism of antioxidant defense. Therefore, Nrf2 activation may be an effective therapeutic strategy for IBD. Here, we reported the development of a nucleus-targeted Nrf2 delivery nanoplatform, termed N/LC, that could accumulate in inflamed colonic epithelium, reduce inflammatory responses, and restore epithelium barriers in a murine model of acute colitis. N/LC nanocomposites could quickly escape from lysosomes, so Nrf2 largely accumulated in the nucleus of colonic cells, activated the Nrf2-ARE signaling pathway, further elevated the expression levels of downstream detoxification and antioxidant genes, and protected cells from oxidative damage. These results suggested that N/LC might be a potential nanoplatform for IBD therapy. The study provided the basis for the biomedical applications of Nrf2-based therapeutics in various diseases.

Apelin expression is downregulated in T cells in a murine model of chronic colitis

Apelin (APL), an endogenous ligand for APJ, has been reported to be upregulated in a murine model of acute colitis induced by sodium dextran sulfate, as well as inflammatory bowel diseases (IBD) in humans. However, the mechanisms and functions of APL/APJ axis in the pathogenesis of IBD are unclear. We herein analyzed CD4+ T cells to determine the functions of APL in a murine model of chronic colitis induced in Rag deficient mice (Rag−/−). In colonic tissues of wild-type mice (WT), we found that APL was expressed especially in the lamina propria lymphocytes, where CD4+ T cells are dominant, rather than the epithelial cells. Unexpectedly, the APL expression was rather downregulated in the colonic tissue of the chronic colitis group compared to the control groups (Rag−/− before colitis induction and WT). The APL expression was downregulated when naïve T cells were differentiated into effecter T cells. A lack of APL resulted in decreased naïve T cells and increased effecter T cells in secondary lymphoid organs. A synthetic APL peptide, [Pyr1]-APL-13, increased IL-10 and decreased IFN-γ productions by effecter T cells. Administration of [Pyr1]-APL-13 improved survival rate in association with lessened colitis severity and decreased pro-inflammatory cytokine production. This is the first report showing immunological function of APL specifically on T cells, and these results indicate that APL/APJ axis may be a novel therapeutic target for IBD.

Probiotic-Inspired Nanomedicine Restores Intestinal Homeostasis in Colitis by Regulating Redox Balance, Immune Responses, and the Gut Microbiome.

Microbiota-based therapeutics offer innovative strategies to treat inflammatory bowel diseases (IBDs). However, the poor clinical outcome so far and the limited flexibility of the bacterial approach call for improvement. Inspired by the health benefits of probiotics in alleviating symptoms of bowel diseases, bioartificial probiotics are designed to restore the intestinal microenvironment in colitis by regulating redox balance, immune responses, and the gut microbiome. The bioartificial probiotic comprises two components: an E. coli Nissle 1917-derived membrane (EM) as the surface and the biodegradable diselenide-bridged mesoporous silica nanoparticles (SeM) as the core. When orally administered, the probiotic-inspired nanomedicine (SeM@EM) adheres strongly to the mucus layer and restored intestinal redox balance and immune regulation homeostasis in a murine model of acute colitis induced by dextran sodium sulfate. In addition, the respective properties of the EM and SeM synergistically alter the gut microbiome to a favorable state by increasing the bacterial diversity and shifting the microbiome profile to an anti-inflammatory phenotype. This work suggests a safe and effective nanomedicine that can restore intestinal homeostasis for IBDs therapy.

OP36 Efficacy and safety of combination induction therapy with guselkumab and golimumab in participants with moderately-to-severely active Ulcerative Colitis: Results through week 12 of a phase 2a randomized, double-blind, active-controlled, parallel-group, multicenter, proof-of-concept study

Abstract Background Preclinical data from a murine model of acute colitis suggest that dual blockade of interleukin(IL)-23 and TNFα more effectively prevented the development of colonic inflammation than each monotherapy. Guselkumab(GUS), an IL-23p19 subunit antagonist, is being studied in inflammatory bowel disease. Golimumab(GOL), a TNFα antagonist, is approved for ulcerative colitis(UC). The objective of this study was to evaluate the efficacy and safety of combination induction therapy with GUS+GOL vs GUS or GOL alone in adults with moderately-to-severely active UC. Methods 214 patients(pts) naïve to TNFα antagonists and refractory or intolerant to conventional therapy(ie, immunomodulators and/or corticosteroids) were randomly assigned to receive GUS 200mg intravenous(IV) at weeks(wks) 0, 4, and 8(n=71); GOL 200mg subcutaneous(SC) at wk0 then 100mg SC at wks2, 6, and 10(n=72); or combination with GUS 200mg IV+GOL 200mg SC at wk0, GOL 100mg SC at wks2, 6, and 10, and GUS 200mg IV at wks4 and 8(n=71). The primary endpoint was clinical response at wk12; the major secondary endpoint was clinical remission at wk12. Other key endpoints were clinical remission based on the modified Mayo score (mMayo), symptomatic remission, endoscopic improvement, endoscopic normalization, histologic remission, composite histologic-endoscopic endpoints, and biomarker outcomes. Results Baseline disease characteristics were similar among groups(Table 1), however a greater proportion of pts in both monotherapy groups had pancolitis vs the combination group. A greater proportion of pts who received combination therapy achieved clinical response at wk12(83.1%) vs GUS(74.6%) or GOL(61.1%)(Table 2). Similarly, the proportion of pts who achieved clinical remission in the combination group(36.6%) was greater than that of monotherapy groups(21.1% and 22.2%, respectively). Clinical remission by mMayo score, endoscopic improvement, histologic remission, both histologic remission and endoscopic improvement, and biomarker normalization (calprotectin, CRP) rates at wk12 were also greater in the combination group vs GUS or GOL. Percentages of pts with endoscopic normalization and both histologic remission and endoscopic normalization were nearly double with combination therapy vs either monotherapy. Adverse event(AE), serious AE, and infection rates were comparable among treatment groups. One pt receiving combination therapy experienced a serious infection of influenza and sepsis. No deaths, malignancies, or TB cases were reported through wk12. Conclusion Combination induction treatment with GUS+GOL more effectively induced clinical response, clinical remission, and endoscopic improvement at wk12 than either monotherapy alone. AE rates were comparable among the treatment groups.

Drug Delivery: Heparin‐Coated Albumin Nanoparticles for Drug Combination in Targeting Inflamed Intestine (Adv. Healthcare Mater. 16/2020)

Targeting areas of inflammation stands to transform the capacity to effectively treat inflammatory bowel disease while minimizing systemic side effects. In article number 2000536, Giovanni Traverso and co-workers describe heparin-coated human serum albumin nanoparticles that can encapsulate drug combination, suppress inflammation in macrophages in vitro, and selectively bind to inflamed intestine in vivo in a murine model of acute colitis.

Bacterial Swarmers Exhibit a Protective Response to Intestinal Stress

Bacterial swarming, a collective movement on a surface, in contrast to sessile biofilms, has rarely been associated with human pathophysiology in health and disease. Here, we report for the first time that bacterial swarmers are associated with protection against intestinal inflammation in a murine model of acute colitis. We show, the presence of bacterial swarmers is highly predictive of intestinal stress in mice, pigs, and humans. We isolated a novel Enterobacter swarming strain, SM3 from mouse feces. In mice, SM3 and other known commensal swarmers, in contrast to their respective swarming-deficient but swimming-competent isogenic strains, demonstrated significant protection from intestinal inflammation. Treatment with SM3 in colitic mice also paralleled a significant reduction in luminal oxygen concentration and enrichment of beneficial anaerobes. Overall, our work identifies a new paradigm in which intestinal stress, allows for the emergence of swarming bacteria, which in turn can protect and heal from intestinal inflammation.

Sestrin3 enhances macrophage-mediated generation of T helper 1 and T helper 17 cells in a mouse colitis model.

Intestinal macrophages participate in the pathogenesis of inflammatory bowel diseases (IBDs) through secreting pro-inflammatory and tissue-damaging factors as well as inducing the differentiation of T helper 1 (Th1) and T helper 17 (Th17) cells. Elucidating the regulatory mechanisms of intestinal macrophage activity in IBDs is important for developing new therapeutic approaches. In the current study, the expression of Sestrins in myeloid cells and lymphocytes in colonic lamina propria (LP) was evaluated in a murine acute colitis model. We found that Sestrin3 was significantly up-regulated in LP macrophages by the colonic LP microenvironment. In the in vitro experiments, lentivirus-mediated Sestrin3 knockdown significantly reduced the production of IL-12 and IL-23 in activated macrophages, in addition to decreasing the expression of classical pro-inflammatory cytokines such as IL-1β, IL-6 and TNF-α. Additionally, Sestrin3 knockdown impaired macrophage-mediated generation of Th1 and Th17 cells from CD4+ T cells, probably through up-regulating the phosphorylation of mechanistic target of rapamycin complex 1 (mTORC1) in macrophages. In the in vivo experiments, adoptive transfer of Sestrin3-deficient macrophages alleviated the generation of Th1 and Th17 cells in the colonic LP and mesenteric lymph nodes. Furthermore, the adoptive transfer mitigated the severity of colitis, as demonstrated by lower production of pro-inflammatory cytokines and fewer tissue lesions in the colon. Our study suggests that Sestrin3 might be crucial for macrophage-mediated generation of pathogenic Th1 and Th17 cells in IBDs.

NKp46+ lamina propria natural killer cells undergo metabolic reprogramming in a mouse experimental colitis model.

Both innate and adaptive immune system play important roles in the onset and progression of inflammatory bowel diseases (IBDs). However, the significance of natural killer (NK) cells for IBDs remains unclear. To understand the biology of colonic lamina propria natural killer (LPNK) cells in IBDs, we characterized LPNK cell metabolism in a murine acute colitis model. C57BL/6J mice were fed with 3% dextran sulfate sodium to establish the acute colitis model. Colonic LPNK cells were isolated from mice through flow cytometry. The expression of metabolic genes in LPNK cells was analyzed by transcriptome sequencing and quantitative RT-PCR. Glucose uptake, Seahorse assay, and ATP assay were conducted to assess the metabolic status of LPNK cells. Phos-flow assay was performed to evaluate cell signaling pathways in LPNK cells. In vitro stimulation and cytotoxicity assay were conducted to measure the function of LPNK cells. In acute colitis, LPNK cells upregulated the expression of genes related to glycolysis and oxidative phosphorylation (oxphos), and enhanced glucose uptake capability. Intracellular ATP production, glycolysis and oxphos in LPNK cells were also promoted in acute colitis. mTORC1 signaling was essential for the metabolic reprogramming in LPNK cells in acute colitis. Although LPNK cells of diseased mice exhibited equivalent cytokine profile to normal LPNK cells upon stimulation with phorbol ester or IL-2, LPNK cells of diseased mice were more cytotoxic to target cells than normal LPNK cells. LPNK cells undergo metabolic reprogramming which might be a response to upcoming microbial infection in acute colitis.

Effects of the microalgae Chlamydomonas on gastrointestinal health

Abstract The effects of consuming whole-cell biomass of the green algae Chlamydomonas reinhardtii on gastrointestinal health in mice and humans was examined. A 14-day murine model of acute colitis revealed significantly less weight loss in mice that received C. reinhardtii biomass by oral gavage. Based on this result, human volunteers with varying gastrointestinal symptoms were asked to consume 1 or 3 g of C. reinhardtii daily for 30 days. Participants reported changes in their gastrointestinal health through a questionnaire and provided stool samples to analyze the composition of their gut microbiome. Those who typically experience frequent gastrointestinal symptoms reported significantly less bowel discomfort or diarrhea, significantly less gas or bloating, more regular bowel movements, and better stool consistency when regularly consuming C. reinhardtii. Analysis of participant stool samples suggested the gut microbiome composition in all groups remained complex, and no signs of dysbiosis or adverse effect on microbial composition were observed.

Materials modulate immunity and gut microbiome.

In a murine model of acute colitis, hyaluronic acid–bilirubin-based nanomaterials have been shown to modulate immune response and the gut microbiome, as well as restore the epithelial barrier.

Hyaluronic acid-bilirubin nanomedicine for targeted modulation of dysregulated intestinal barrier, microbiome and immune responses in colitis.

While conventional approaches for inflammatory bowel diseases (IBD) mainly focus on suppressing hyperactive immune responses, it remains unclear how to address disrupted intestinal barriers, dysbiosis of the gut commensal microbiota, and dysregulated mucosal immune responses in IBD. Moreover, immunosuppressive agents can cause off-target systemic side effects and complications. Here, we report the development of hyaluronic acid-bilirubin nanomedicine (HABN) that accumulates in inflamed colonic epithelium and restores the epithelium barriers in a murine model of acute colitis. Surprisingly, HABN also modulated the gut microbiota, increasing the overall richness and diversity and markedly augmenting the abundance of Akkermansia muciniphila and Clostridium XIVα, microorganisms with crucial roles in gut homeostasis. Importantly, HABN associated with pro-inflammatory macrophages, regulated innate immune responses, and exerted potent therapeutic efficacy against colitis. Our work sheds new light on the impact of nanotherapeutics on gut homeostasis, microbiome, and innate immune responses for the treatment of inflammatory diseases.

Tu1775 - A Novel Ogr1 (GPR68) Inhibitor Attenuates Inflammation in a Murine Model of Acute Colitis

Tu1775 - A Novel Ogr1 (GPR68) Inhibitor Attenuates Inflammation in a Murine Model of Acute Colitis

P074 Human amnion epithelial cells reduce intestinal inflammation in a dextran sulfate sodium-induced murine model of acute colitis

Inflammatory bowel disease encompasses a group of conditions characterised by inflammation and ulceration of the colon resulting in diarrhoea, haematochezia and weight loss. This often requires hospitalisation, corticosteroids and long-term immunosuppressants. However, these treatments are associated with numerous side effects and a subset of patients remain refractory to treatment. Stem cells, such as the pluripotent human amnion epithelial cells (hAECs), have been explored as a potential therapy. Ethically sourced from placentas, hAECs possess anti-inflammatory properties and no known safety issues. We examined the efficacy of hAECs in a dextran sulfate sodium (DSS) induced murine model of acute colitis. C57BL/6J mice received 2% DSS (w/v) in their normal drinking water for 7 days. At Day 2, Group 1 (n = 17) received a tail vein of 2 × 106 hAECs. At Day 4, Group 2 (n = 17) received an injection of 2 × 106 hAECs. DSS control mice (n = 17) were untreated. Mice were monitored daily and culled at Day 8. Colitis severity was scored histologically using H&E stained colon sections. Colonic neutrophil infiltration was determined by myeloperoxidase (MPO) activity assay. IL-1β, TNF-α, IL-6, IFN-γ and IL-10 were measured through enzyme-linked immunosorbent assays. Colon sections were stained with anti-F/480 antibody to identify macrophages. Untreated DSS mice lost significantly more body weight (−17.4%) compared with hAEC treated mice (Group 1: −5.6% (p < 0.0001), Group 2: −8.8% (p < 0.0001)). Treatment prevented colon shortening in Group 1 (6.7 cm p < 0.001) and Group 2 (6.3 cm, p < 0.01) compared with controls (5.3 cm). Similarly, hAEC treated mice had significantly lower histological severity scores (Group 1: p < 0.0001, Group 2: p < 0.001). MPO activity was almost halved in Groups 1 (p < 0.0001) and 2 (p < 0.0001). Treatment also significantly reduced concentrations of pro-inflammatory cytokines (IL-1β, TNF-α, IL-6, IFN-γ) whilst up-regulating the anti-inflammatory cytokine IL-10. hAEC treatment significantly reduced intestinal macrophages at Day 2 (p < 0.01) but not Day 4. Apart from a lower histological severity score in Group 1, there were no others differences comparing Group 1 and 2. hAECs exert a protective effect in colitis and reduce the severity of disease, by reducing the level of neutrophil and macrophage infiltration into the colon and decreasing concentrations of pro-inflammatory cytokines and increasing anti-inflammatory cytokine. The therapeutic potential of hAECs in IBD is promising and further research into their optimal delivery and mechanisms of action is warranted.

P087 A novel OGR1 (GPR68) inhibitor attenuates inflammation in a murine model of Acute Colitis

P087 A novel OGR1 (GPR68) inhibitor attenuates inflammation in a murine model of Acute Colitis

Basic Science Luminal

Basic Science Luminal

Chromosome region maintenance-1 (CRM1) regulates apoptosis of intestinal epithelial cells via p27kip1 in Crohn's disease

To investigate the role of chromosome region maintenance-1 (CRM1) in Crohn's disease (CD) and its potential pathological mechanisms. The expression and distribution of CRM1 in mucosal biopsies from patients with active CD and normal controls were detected by immunohistochemistry (IHC). We established a murine model of acute colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS). Western blot was performed to investigate the expression levels of CRM1, apoptotic markers (active caspase-3 and cleaved PARP), p27kip1 and p-p27ser10. IHC was performed to evaluate the distribution of CRM1, and double immunofluorescence (IF) was performed to evaluate the co-localization of CRM1 and active capase-3. Cells of the human intestinal epithelial cell line HT-29 were incubated with tumor necrosis factor-α (TNF-α) to establish an apoptotic in vitro model. Western blot was performed to determine the expression levels of CRM1, active caspase-3, cleaved PARP and p-p27ser10. Cytoplasmic and nuclear extracts were assessed to examine the translocation of CRM1. The interaction between CRM1 and p27kip1 was assessed by co-immunoprecipitation (co-IP) assays. Furthermore, we used small interfering RNA (siRNA) to knock down the protein expression of CRM1 in HT-29 cells and then measured the expression of active caspase-3, cleaved PARP and p-p27ser10. Flow cytometry was used to determine the effect of CRM1 on intestinal epithelial cell (IEC) apoptosis. We observed up-regulation of CRM1 accompanied by elevated levels of IEC apoptotic markers (active caspase-3 and cleaved PARP) and p-p27ser10 in IECs of patients with active CD and in TNBS-induced colitis model cells. However, the expression of p27kip1 was negatively correlated with the expression patterns of CRM1, p-p27ser10 and apoptotic biochemical markers. Co-localization of CRM1 and active caspase-3 in IECs of the TNBS group further indicated the possible involvement of CRM1 in IEC apoptosis. By employing TNF-α-treated HT-29 cells as an in vitro IEC apoptosis model, we found that the expression levels of CRM1 and p-p27ser10 were in accordance with active caspase-3 and cleaved PARP. In addition, immunoprecipitation confirmed the physical interaction between CRM1 and p27kip1. siRNA knockdown of CRM1 significantly inhibited the phosphorylation of p27kip1 and the expression of active caspase-3 and cleaved PARP. In addition, flow cytometry analysis also showed that silencing CRM1 by siRNA inhibited TNF-α-induced cellular apoptosis in HT-29 cells. Up-regulated CRM1 may facilitate IEC apoptosis possibly through p27kip1 in CD, indicating an important role of CRM1 in the pathophysiology of CD.