Jianfeng Gong

Epithelial-specific blockade of MyD88-dependent pathway causes spontaneous small intestinal inflammation

Accumulating evidence suggests a role for Toll-like receptor (TLR) signaling at the intestinal epithelial cells (IECs) level for intestinal protection against exogenous injury or pathogenic infection. We hypothesized that MyD88 dependent TLR signaling at intestinal epithelium is critical for mucosal immune homeostasis. In the current study, a transgenic mouse model was generated in which a dominant-negative mutant of MyD88 (dnMyD88) was driven by an intestinal epithelial-specific murine villin promoter. Aged transgenic mice spontaneously developed chronic small intestinal inflammation, as revealed by increased CD4+ and CD8+ lymphocytes, neutrophil and macrophage infiltration, increased production of cytokines as TNF-alpha, IFN-gamma, IL-1beta, and IL-17, crypt abscesses, lymphedema, and Goblet cell depletion. The chronic inflammation was not due to increased epithelial apoptosis or permeability, but to a decreased Paneth cell-derived alpha-defensins (cryptdins) and RegIII-gamma and increased commensal bacteria translocation. Thus, epithelial MyD88-dependent pathway plays an essential role in limiting mucosal microflora penetration and preventing mucosal immunoregulation disturbance in vivo.

Use of Thiopurines and Risk of Colorectal Neoplasia in Patients with Inflammatory Bowel Diseases: A Meta-Analysis

Objective Inflammatory bowel disease (IBD) is commonly treated with thiopurines such as azathioprine and mercaptopurine for the maintenance of remission. Studies examining chemopreventive of these medications on colorectal neoplasm in IBD patients have yielded conflicting results. We performed a meta-analysis to assess the role of thiopurines for this indication. Methods We performed a systematic search of PubMed, Web of Science, EMBASE and Cochrane to identify studies reporting colorectal neoplasm from IBD patients treated with thiopurines and conducted a meta-analysis of pooled relative risk (RR) using the random effects model. Results Nine case-control and ten cohort studies fulfilled the inclusion criteria. The use of thiopurines was associated with a statistically significant decreased incidence of colorectal neoplasm (summary RR=0.71, 95% CI=0.54–0.94, p=0.017), even after adjustment for duration and extent of the disease, but there was high heterogeneity among studies (I 2=68.0%, p<0.001). The RR of advanced neoplasm (high-grade dysplasia and cancer) was 0.72 (95%CI=0.50–1.03, p=0.070) and that of cancer was 0.70 (95% CI=0.46–1.09, p=0.111) for thiopurine-treated patients. Heterogeneity of the studies was affected by the sample size (</≥100 cases) and whether the patients had longstanding colitis (≥7 years). Conclusion The current meta-analysis revealed that thiopurines had a chemopreventive effect of colorectal neoplasms and a tendency of reducing advanced colorectal neoplasms in IBD. Due to the heterogeneity of included studies, these results should be interpreted with caution.

Altered microRNA expression in inflamed and non-inflamed terminal ileal mucosa of adult patients with active Crohn's disease.

MicroRNAs (miRNAs) play an important role in inflammation. Several studies have reported the unique miRNA profiles in colonic mucosa and peripheral blood of patients with active Crohns disease (CD). But there is limited data about the miRNA profiles of the terminal ileum, the most commonly involved location, especially the non‐inflamed mucosa. We aimed to investigate the miRNA expression of both inflamed and non‐inflamed terminal ileal mucosa in adult patients with active CD.

Berberine Ameliorates Pro-inflammatory Cytokine-Induced Endoplasmic Reticulum Stress in Human Intestinal Epithelial Cells In Vitro

Endoplasmic reticulum stress (ER stress) in intestinal epithelial cells (IECs) plays an important role in the pathogenesis and perpetuation of inflammatory bowel disease (IBD). The aim of this study is to explore the potential of berberine (BBR) in regulating pro-inflammatory cytokine-induced ER stress and apoptosis in IECs. ER stress in cultured Caco-2 cells was induced by IFN-γ/TNF-α and tunicamycin, respectively. The experimental groups were pretreated with BBR. Cell viability was determined by MTT assay. In vitro apoptosis was examined by flow cytometry using annexin V-FITC labeling. The molecular markers of ER stress, including GRP-78, p-JNK, caspase-12, and cleaved caspase-3 were analyzed by Western blot. Xbp-1 mRNA splicing was detected by RT-PCR. Pretreatment of BBR helped to survive in cytokine-induced Caco-2 cells. BBR significantly attenuated cytokine-induced Caco-2 apoptosis. GRP78 expression and xbp-1 mRNA splicing were enhanced significantly in the presence of IFN-γ/TNF-α and tunicamycin, and they could be dampened by BBR. Further study revealed BBR could downregulate JNK phosphorylation, and the level of caspase-12 and cleaved caspase-3. Berberine can ameliorate pro-inflammatory cytokines induced ER stress in vitro, and it might be one of the targeted therapeutic agents for IBD.

Fstl1 antagonizes BMP signaling and regulates ureter development.

Bone morphogenetic protein (BMP) signaling pathway plays important roles in urinary tract development although the detailed regulation of its activity in this process remains unclear. Here we report that follistatin-like 1 (Fstl1), encoding a secreted extracellular glycoprotein, is expressed in developing ureter and antagonizes BMP signaling activity. Mouse embryos carrying disrupted Fstl1 gene displayed prominent hydroureter arising from proximal segment and ureterovesical junction defects. These defects were associated with significant reduction in ureteric epithelial cell proliferation at E15.5 and E16.5 as well as absence of subepithelial ureteral mesenchymal cells in the urinary tract at E16.5 and E18.5. At the molecular level, increased BMP signaling was found in Fstl1 deficient ureters, indicated by elevated pSmad1/5/8 activity. In vitro study also indicated that Fstl1 can directly bind to ALK6 which is specifically expressed in ureteric epithelial cells in developing ureter. Furthermore, Sonic hedgehog (SHH) signaling, which is crucial for differentiation of ureteral subepithelial cell proliferation, was also impaired in Fstl1-/- ureter. Altogether, our data suggest that Fstl1 is essential in maintaining normal ureter development by antagonizing BMP signaling.

Exclusive enteral nutrition ameliorates mesenteric adipose tissue alterations in patients with active Crohn's disease

BACKGROUND & AIMS Mesenteric adipose tissue hypertrophy is a hallmark of Crohns disease and can express various adipokines. Exclusive enteral nutrition could effectively induce remission in Crohns disease with mechanisms largely unknown. We investigated whether exclusive enteral nutrition could modify mesenteric fat in patients with active Crohns disease. METHODS Sixteen patients who underwent resection for ileum Crohns disease were studied. As a control group, eight patients without inflammatory bowel disease were enrolled. Before operation, eight Crohns disease patients received exclusive enteral nutrition for four weeks, and the other patients had no nutritional therapy. The mesenteric fat samples were obtained during operation. Adipocyte size, adipokine production and topical C-reactive protein level were assessed. RESULTS The adipocyte size from patients treated with exclusive enteral nutrition was much larger than that from Crohns disease patients without nutritional therapy. Furthermore, protein levels of proinflammatory adipokines such as TNF-alpha and leptin were lower while protein level of adiponectin was higher in these patients. As to mRNA level, the expression of adiponctin was up-regulated and leptin was down-regulated in the patients received enteral nutrition. CONCLUSIONS Exclusive enteral nutrition could ameliorate mesenteric fat alterations which are associated with intestinal injury in patients with Crohns disease by restoring adipocyte morphology and diminishing the inflammatory environment of mesenteric fat.

A Practical Predictive Index for Intra-abdominal Septic Complications After Primary Anastomosis for Crohn's Disease: Change in C-Reactive Protein Level Before Surgery.

BACKGROUND: Postoperative intra-abdominal septic complications are difficult to manage in Crohn’s disease, which makes prevention especially important. OBJECTIVE: The purpose of this study was to examine the risk factors for intra-abdominal septic complications after primary anastomosis for Crohn’s disease and to seek a practical predictive index for intra-abdominal septic complications. DESIGN: This was a retrospective study. SETTINGS: The study was conducted in a tertiary referral hospital. PATIENTS: Based on a computerized database of 344 patients with Crohn’s disease who underwent primary anastomosis between 2004 and 2013, the patients were placed into an intra-abdominal septic complications group and a group without intra-abdominal septic complications. MAIN OUTCOME MEASURES: Univariate and multivariate analyses were performed to identify risk factors, and the predictive accuracy of possible predictors was assessed using receiver operating characteristic curves. RESULTS: Overall, 39 patients (11.34%) developed intra-abdominal septic complications. Preoperative C-reactive protein level >10 mg/L was found to be an independent risk factor (p < 0.01) for intra-abdominal septic complications. For prediction of intra-abdominal septic complications, receiver operating characteristic curve analysis showed that a C-reactive protein cutoff of 14.50 mg/L provided negative and positive predictive values of 96.84% and 34.07%. In addition, the change in C-reactive protein levels over the 2 weeks before surgery was greater in the intra-abdominal septic complications group than the group with no intra-abdominal septic complications (p < 0.01), and the directions of change were opposite, upward in the former and downward in the latter. Apart from being a risk factor for intra-abdominal septic complications (p < 0.01), receiver operating characteristic curve analysis showed that the change in C-reactive protein levels before surgery had a negative predictive value for intra-abdominal septic complications of 98.66% and a positive predictive value of 76.09%. LIMITATIONS: This was a retrospective study. CONCLUSIONS: Changes in C-reactive protein before surgical treatment of Crohn’s disease could serve as a practical predictive index for postoperative intra-abdominal septic complications.

Berberine reduces rat intestinal tight junction injury induced by ischemia-reperfusion associated with the suppression of inducible nitric oxide synthesis.

Berberine (BBR) has been shown to attenuate the deleterious effects of ischemia/reperfusion (I/R) injury in the brain. We evaluated the effects of BBR on intestinal tight junction (TJ) changes during mesenteric I/R. I/R was induced in rats by the occlusion of the superior mesenteric artery and reperfusion. The rats were randomized into four groups: control, BBR, I/R, and I/R + BBR. Intestinal permeability was determined by the lactulose/mannitol test. The ileum and colon were harvested to assess mucosal injury and inducible nitric oxide synthase activity. The TJ ultrastructure was studied by transmission electron microscopy. The expressions and locations of the TJ proteins, occludin and ZO-1, in the epithelium were investigated by immunofluorescence microscopy. We also used Western blot analysis to detect the distribution of TJ proteins in lipid raft fractions. Our results suggest that I/R-induced intestinal TJ dysfunction can be improved by BBR, thereby demonstrating the therapeutic potential of BBR for intestinal I/R.

Celastrol ameliorates experimental colitis in IL-10 deficient mice via the up-regulation of autophagy.

BACKGROUND Celastrol had been proved effective in the treatment for IBD, probably with the modulation of oxidative stress, inflammatory cytokines and intestinal homeostasis. This study was aimed to investigate whether celastrol could ameliorate the inflammation of IL-10 deficient mice, a murine model of Crohns disease (CD) with the induction of autophagy. MATERIAL AND METHODS The mice included were divided into four groups, ##WT group, IL-10(-/-) group, Cel group and Control group (celastrol+3-Methyladenine). Celastrol (2 mg/kg) treatment by gavage was administered to mice daily over one week. 3-Methyladenine (autophagy inhibitors) was administered at a dose of 30 mg/kg by intraperitoneal injection. The histological evaluation of the colon, tissue myeloperoxidase (MPO), and colon inflammation of mice in the four groups was evaluated and compared. Furthermore, the PI3K/Akt/mTOR pathway and the status of autophagy in intestine affected by celastrol were also assessed. RESULTS The one-week administration of celastrol ameliorated established colitis in IL-10 deficient mice, associated with a reduction of marked histological inflammation, a decreased colon MPO concentration and suppression of colonic proinflammatory cytokine. Furthermore, the decreased neutrophil infiltration in proximal colon and improvement of inflammation in the Cel group was much more obvious than that in the Control group. The Western blotting analysis of the PI3K/Akt/mTOR pathway and autophagy showed that celastrol treatment up-regulated the autophagy of colon tissue by suppressing the PI3K/Akt/mTOR signaling pathway. CONCLUSIONS Celastrol ameliorates experimental colitis in IL-10 deficient mice via the up-regulation of autophagy by suppressing the PI3K/Akt/mTOR signaling pathway.

Cigarette smoking is associated with intestinal barrier dysfunction in the small intestine but not in the large intestine of mice

AIMS To observe the effect of cigarette smoke (CS) on the small bowel and colon in mice and to attempt to explain the potential mechanisms that account for these effects. METHODS Male BALB/c mice age 6-8 weeks were randomly divided into a CS group and a control group (n=10 per group). CS mice were exposed to CS (five cigarettes each time, four times a day for 5 days a week using Hamburg II smoking machine and CS was diluted with air at a ratio of 1:6) for 10 weeks, and control mice were exposed to room air. After 10 weeks, mice were sacrificed for analysis (colon and small bowel). RESULTS CS exposure impaired the intestinal barrier of the small bowel, based on evidence that CS mice exhibited increased intestinal permeability, bacterial translocation, intestinal villi atrophy, damaged tight junctions and abnormal tight junction proteins. These changes were partly mediated through the activated NF-κB (p65) signalling pathway. However, no obvious changes associated with the intestinal barrier were identified in the small bowel of control mice or the colons of control or CS mice. CONCLUSIONS CS is associated with intestinal barrier dysfunction in the small intestine but not in the large intestine of mice.