Cindy W. Lau

The Membrane-Bound Mucin Muc1 Regulates T Helper 17-Cell Responses and Colitis in Mice

BACKGROUND & AIMS T helper (Th) 17 cells produce the effector cytokine interleukin (IL)-17, along with IL-22, which stimulates colonic epithelial cells to produce a membrane-bound mucin, Muc1. Muc1 is a component of the colonic mucus, which functions as a lubricant and a physiologic barrier between luminal contents and mucosal surface. The gene MUC1 has been associated with susceptibility to inflammatory bowel disease; we investigated the role of Muc1 in development of colitis in mice. METHODS Muc1 and RAG1 were disrupted in mice (Muc/RAG double knockout mice); Th1-mediated colitis was induced by intravenous injection of CD4(+)CD45RB(high) T cells. We also studied Th2-mediated colitis using mice with disruptions in Muc1 and T-cell receptor α chain (Muc/TCR double knockout mice). RESULTS Muc1 deficiency led to the development of more severe forms of Th1- and Th2-induced colitis than controls. Loss of Muc1 increased colonic permeability and the Th17-cell, but not Th2 or Th1 cell, response in the inflamed colon. Loss of Muc1 also promoted expansion of an innate lymphoid cell population (Lin(-) ckit(-) Thy1(+) Sca1(+)) that produces IL-17. The expansion of Th17 adaptive immune cells and innate lymphoid cells required the commensal microbiota. CONCLUSIONS Muc1, which is up-regulated by Th17 signaling, functions in a negative feedback pathway that prevents an excessive Th17 cell response in inflamed colons of mice. Disruption of this negative feedback pathway, perhaps by variants in Muc1, might contribute to inflammatory bowel disease in patients.

Chitinase 3-Like-1 Expression in Colonic Epithelial Cells as a Potentially Novel Marker for Colitis-Associated Neoplasia

Chitinase 3-like-1 (CHI3L1/YKL-40) is a protein secreted from restricted cell types including colonic epithelial cells (CECs) and macrophages. CHI3L1 is an inflammation-associated molecule, and its expression is enhanced in persons with colitis and colon cancer. The biological function of CHI3L1 on CECs is unclear. In this study, we investigated the role of CHI3L1 on CECs during the development of colitis-associated neoplasia. We analyzed colonic samples obtained from healthy persons and from persons with ulcerative colitis with or without premalignant or malignant changes. DNA microarray and RT-PCR analyses significantly increased CHI3L1 expression in non-dysplastic mucosa from patients with inflammatory bowel disease (IBD) who had dysplasia/adenocarcinoma compared with that in healthy persons and in patients with IBD who did not have dysplasia. As determined by IHC, CHI3L1 was expressed in specific cell types in the crypts of colonic biopsies obtained from patients with ulcerative colitis who have remote dysplasia. Purified CHI3L1 efficiently activated the NF-κB signaling pathway and enhanced the secretion of IL-8 and TNF-α in SW480 human colon cancer cells. In addition, colon cancer cell proliferation and migration were significantly promoted in response to CHI3L1 in these cells. In summary, CHI3L1 may contribute to the proliferation, migration, and neoplastic progression of CECs under inflammatory conditions and could be a useful biomarker for neoplastic changes in patients with IBD.

Chitin microparticles for the control of intestinal inflammation

Background: Chitin is a polymer of N‐acetylglucosamine with the ability to regulate innate and adaptive immune responses. However, the detailed mechanisms of chitin‐mediated regulation of intestinal inflammation are only partially known. Methods: In this study chitin microparticles (CMPs) or phosphate‐buffered saline (PBS) were orally administered to acute and chronic colitis models every 3 days for 6 consecutive weeks beginning at weaning age. The effects of this treatment were evaluated by histology, cytokine production, coculture study, and enteric bacterial analysis in dextran sodium sulfate (DSS)‐induced colitis or T‐cell receptor alpha (TCR&agr;) knockout chronic colitis models. Results: Histologically, chitin‐treated mice showed significantly suppressed colitis as compared with PBS‐treated mice in both animal models. The production of interferon‐gamma (IFN‐&ggr;) was upregulated in the mucosa of chitin‐treated mice compared with control mice. The major source of IFN‐&ggr;‐producing cells was CD4+ T cells. In mouse dendritic cells (DCs) we found that CMPs were efficiently internalized and processed within 48 hours. Mesenteric lymph nodes (MLNs) CD4+ T cells isolated from chitin‐treated mice produced a 7‐fold higher amount of IFN‐&ggr; in the culture supernatant after being cocultured with DCs and chitin as compared with the control. Proliferation of carboxyfluorescein succinimidyl ester (CFSE)low CD4+ T cells in MLNs and enteric bacterial translocation rates were significantly reduced in chitin‐treated mice when compared with the control. In addition, CMPs improved the imbalance of enteric bacterial compositions and significantly increased interleukin (IL)‐10‐producing cells in noninflamed colon, indicating the immunoregulatory effects of CMPs in intestinal mucosa. Conclusions: CMPs significantly suppress the development of inflammation by modulating cytokine balance and microbial environment in colon. (Inflamm Bowel Dis 2012;)

Inducible colitis-associated glycome capable of stimulating the proliferation of memory CD4+ T cells

The colitis-associated glycome mediates CD4+ T cell expansion and contributes to the exacerbation of T cell–mediated intestinal inflammation.

Regulatory B cells in mouse models of intestinal inflammation.

Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory condition with increasing incidence and prevalence around the world. Although B cells had generally been believed to play a pathogenic role in IBD due to the production of autoantibodies, a growing body of evidence from mouse models suggests the coexistence of pathogenic B cells and regulatory B cells, termed Breg, in this disorder. Since some unique techniques are required to closely study the Breg in gut-associated lymphoid tissues (GALT), we herein describe how to induce colitis in mice and how to analyze the phenotype and function of GALT-specific Breg.

Examination of the Role of Galectins in Intestinal Inflammation

The intestine, which provides the first line of defense against over trillion of enteric microorganisms, suffers from broad range of inflammatory conditions caused by infectious, autoimmune, allergic, neurological, and ischemic mechanisms. Recent data have suggested dual roles (protective versus deleterious) for galectins in the pathogenesis of some intestinal inflammations, highlighting the importance of this area of research. A potential problem with the research of intestinal inflammation may be the requirement of some unique techniques. Therefore, we herein describe how to induce intestinal inflammation and how to isolate lymphocyte, myeloid cell, follicular cell, and epithelial cell populations separately from the intestine for the study of intestinal inflammations.

Glycosylated Chitinase 3-Like 1 Protein and Chitin-Binding Motif of Potentially Pathogenic E. coli Play a Critical Role in Host-Microbial Interactions

response to ATP (5 mM) than control group after 3h (291 ± 4.6 versus 55.85 ± 1.9, respectively, p < 0.0001). IL-β secretion was completely abrogated when ATP was preincubated with cIAP (200 units/ml) for 2 h. Conclusions: We hypothesize that IAP could play a role in protecting the host against excessive gut inflammation induced by extracellular danger signals like ATP. These processes are critical to the fundamental understanding of the gut mucosal enzyme defense system which maintains gut homeostasis. IAP could represent a novel therapy for human IBD.