Role of Mucin-type O-glycans in Intestinal Inflammation

粘蛋白型 O-聚糖在肠道炎症中的作用

• 批准号: 8117759
• 负责人: Lijun Xia
• 金额: $ 32.2万
• 依托单位: OKLAHOMA MEDICAL RESEARCH FOUNDATION
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8117759
• 关键词: Abscess; Age; Anabolism; Bacterial Translocation; Biological Models; Biological Process; Biopsy Specimen; Cells; Chronic; Colitis; Colon; DNA; Data; Derivation procedure; Development; Disease; Epithelial; Epithelial Cells; Epithelium; Etiology; Exhibits; Galactosyltransferases; Gel; Genes; Germ-Free; Gnotobiotic; Human; Immune; Impairment; Infiltration; Inflammation; Inflammatory disease of the intestine; Intestinal Secretions; Intestines; Label; Large Intestine; Lead; Mediating; Mediator of activation protein; Metabolic; Missense Mutation; Modeling; Molecular; Molecular Chaperones; Mucins; Mucositis; Mucous Membrane; Mucous body substance; Mus; Mutant Strains Mice; Mutation; Myeloid Cells; Onset of illness; Pathogenesis; Patients; Phylogenetic Analysis; Polysaccharides; Rag1 Mouse; Research; Role; Sampling; Services; Severities; Somatic Mutation; Staining method; Stains; Structure; Tamoxifen; Testing; Tissues; Ulcerative Colitis; Work; X Chromosome; adaptive immunity; base; density; disability; gastrointestinal epithelium; glycosylation; granulocyte; human disease; improved; insight; novel; novel therapeutics; psychologic; public health relevance; sugar; trafficking

DESCRIPTION (provided by applicant): Mucin-type O-glycans are primary components of the colonic mucus gel layer. Altered intestinal O- glycosylation has been observed in patients with ulcerative colitis (UC), but whether this alteration is an etiological factor is unknown. O-glycans consist mainly of core 1- and core 3-derived O-glycans. The biosynthesis of these two types of O-glycans is controlled by core 11,3-galactosyltransferase (T-synthase) and Core 31,3-glucosaminyltransferase (C3GnT), respectively. T-synthase function requires a specific chaperone, Cosmc. Human Cosmc is on the X-chromosome, increasing the significance of somatic mutations in this gene. In preliminary studies, we detected somatic mutations in the Cosmc gene in DNA, isolated from colonic epithelial cells, expressing abnormal O-glycans from UC patients. We hypothesize that altered O-glycans impair mucus barrier function, which in turn allows intestinal microflora to interact abnormally with epithelium and mucosal immune cells, thus causing colitis. To test this hypothesis, we developed mice lacking either core 1- or combined core 1- and core 3-derived O-glycans (IEC T-syn-/- and DKO mice, respectively). In addition, we have also developed mice with tamoxifen (TM) inducible deletion of T-syn in intestinal epithelial cells (TM-IEC T-syn-/-). These mice develop spontaneous colitis, which is associated with a massive granulocyte infiltration and cryptic abscesses, closely resembling active human UC. Significantly, IEC T-syn-/- and DKO mice in the Rag1-/- background, who lack adaptive immunity, manifested similarly severe colitis, suggesting an essential role for innate immune cells such as granulocytes in colitis development. This supports an etiological role for O-glycans in colitis and provides a unique model system to test whether altered O-glycans is a potential molecular mechanism in the pathogenesis of human UC. We propose to 1) analyze how abnormal O-glycosylation impairs the expression of intestinal mucins and add additional patient samples to improve the statistical power of our preliminary observations that Cosmc mutations cause abnormal expression of colon epithelial O-glycans in UC patients; 2) determine the role of O- glycans in intestinal barrier function, investigate changes in bacterial variety or density in O-glycan-deficient mice before and after disease onset by phylogenetic analysis, and test definitively the role of microbiota in colitis development by developing germ-free O-glycan-deficient mice; and 3) identify mechanisms initiating granulocyte infiltration and determine the role of granulocytes in colitis. Our proposed studies will reveal novel insights into the pathogenesis of colitis and may lead to new therapies. PUBLIC HEALTH RELEVANCE: Ulcerative colitis (UC) is a chronic inflammation of the large intestine with an unknown cause or cure that can last years to decades. UC often leads to physical as well as psychological discomfort and even disability. Altered expression of large sugar molecules called O-glycans in the large intestine is seen in UC patients. However, whether this alteration causes the disease is unknown. The proposed project is poised to provide novel insights into the role of intestinal mucin-type O-glycans in intestinal mucus barrier function and in pathogenesis of the common human disease. This work may lead to a novel therapy for patients with UC.

性状（由申请方提供）：粘蛋白型O-聚糖是结肠粘液凝胶层的主要组分。在溃疡性结肠炎（UC）患者中观察到肠道O-糖基化改变，但这种改变是否是一个病因尚不清楚。O-聚糖主要由核心1-和核心3-衍生的O-聚糖组成。这两种类型的O-聚糖的生物合成分别由核心11，3-半乳糖基转移酶（T-合成酶）和核心31，3-葡糖胺基转移酶（C3 GnT）控制。T-合酶的功能需要一个特定的伴侣，Cosmc。人类Cosmc位于X染色体上，增加了该基因体细胞突变的重要性。在初步研究中，我们检测到DNA中Cosmc基因的体细胞突变，从结肠上皮细胞中分离，表达UC患者的异常O-聚糖。 我们假设改变的O-聚糖损害粘液屏障功能，这反过来又允许肠道微生物菌群与上皮和粘膜免疫细胞异常相互作用，从而引起结肠炎。为了检验这一假设，我们开发了缺乏核心1-或组合的核心1-和核心3-衍生的0-聚糖的小鼠（分别为IEC T-syn-/-和DKO小鼠）。此外，我们还开发了在肠上皮细胞中具有他莫昔芬（TM）诱导的T-syn缺失的小鼠（TM-IEC T-syn-/-）。这些小鼠发生自发性结肠炎，其与大量粒细胞浸润和隐蔽性溃疡相关，非常类似于活动性人类UC。值得注意的是，缺乏适应性免疫的Rag 1-/-背景中的IEC T-syn-/-和DKO小鼠表现出类似的严重结肠炎，表明先天免疫细胞如粒细胞在结肠炎发展中的重要作用。这支持了O-聚糖在结肠炎中的病因学作用，并提供了一个独特的模型系统来测试改变的O-聚糖是否是人类UC发病机制中的潜在分子机制。 我们建议1）分析异常O-糖基化如何损害肠粘蛋白的表达，并增加额外的患者样本以提高我们初步观察的统计功效，即Cosmc突变导致UC患者中结肠上皮O-聚糖的异常表达; 2）确定O-聚糖在肠屏障功能中的作用，通过系统发育分析研究疾病发作前后O-聚糖缺陷小鼠中细菌种类或密度的变化，并通过开发无菌O-聚糖缺陷小鼠明确测试微生物群在结肠炎发展中的作用;和3）鉴定启动粒细胞浸润的机制并确定粒细胞在结肠炎中的作用。我们提出的研究将揭示结肠炎发病机制的新见解，并可能导致新的治疗方法。 公共卫生相关性：溃疡性结肠炎（UC）是一种慢性大肠炎症，其原因或治疗方法不明，可持续数年至数十年。UC通常会导致身体和心理上的不适，甚至残疾。在UC患者中观察到大肠中称为O-聚糖的大糖分子的表达改变。然而，这种改变是否会导致疾病尚不清楚。该项目有望为肠粘蛋白型O-聚糖在肠粘液屏障功能和常见人类疾病发病机制中的作用提供新的见解。这项工作可能会为UC患者带来新的治疗方法。