Paneth Cell Secreted Effectors in Mucosal Innate Immunity

粘膜组织的免疫系统必须有效地保护宿主免受病原体的入侵， 促进与多种定殖微生物群的稳态相互作用。对关键的清晰认识 实现这种微妙平衡的分子和机制仍然不完整，在关键领域留下了空白。 知识小肠的潘氏细胞分泌大量的蛋白质和肽到管腔中 介导宿主防御和维持体内平衡的相互关联的功能。引人注目 包括我们在内的许多实验室发表的证据表明，潘氏细胞功能缺陷 增加对慢性炎症性肠病（IBD）和肠道病原体的易感性。这 研究将集中在一种分泌蛋白质上，我们的初步数据表明，这种蛋白质是最丰富的 人潘氏细胞的分泌蛋白，一种研究不足的肠凝集素，名为intelectin。肠凝集素 直向同源物广泛地跨越动物王国，从哺乳动物到无脊椎动物海square。近期刊发 数据表明，intelectin具有先天免疫的分子模式结合活性特征， 系统，因为它结合到各种微生物上发现的碳水化合物-通过与环外1，2 二醇-但由于空间位阻而不与主体碳水化合物结合。我们的初步数据表明 小肠细胞中两种同种型白细胞凝集素（ITLN 1和ITLN 2）的定性和定量畸变 来自患有回肠克罗恩病（CD）的个体的样本与对照相比。虽然在统计学上显著， 可能将这些变化与CD先天免疫受损联系起来的机制尚不清楚， 研究了我们的假设，基于已发表的和初步的数据，是intelectin是一个关键的调解人 宿主和微生物之间的相互作用。目的1将确定ITLN 1和ITLN 2的相对表达水平。 ITLN 2在小肠CD和对照标本中的表达，并对分离自 人类小肠目的2研究intelectin异构体的体外活性。目标3将 使用新产生C57 BL/6 Itln-/-建立白细胞凝集素表达的先天免疫学结果 小鼠我们的目标是阐明对intelectin在粘膜保护中的作用的基本理解， 这样做，填补了我们对人类Paneth的保守的、高度丰富的分泌蛋白的理解的空白 细胞这些研究的成功完成可能会对我们的机械理解产生广泛的影响 小肠内的先天免疫。

The immune system of mucosal tissues must effectively protect the host from pathogen invasion, while facilitating homeostatic interactions with a diverse colonizing microbiota. A clear understanding of the key molecules and mechanisms that achieve this delicate balance remains incomplete, leaving a gap in critical knowledge. Paneth cells of the small intestine secrete large quantities of proteins and peptides into the lumen that mediate both interrelated functions of host defense and maintenance of homeostasis. Compelling published evidence from many laboratories, including ours, suggests that defective Paneth cell function increases susceptibility to chronic inflammatory bowel disease (IBD) and to enteric pathogens. This investigation will focus on a secreted protein that our preliminary data suggests is among the most abundant secretory proteins of human Paneth cells, an understudied intestinal lectin named intelectin. Intelectin orthologs widely span the animal Kingdom, from mammals to the invertebrate sea squirts. Recent published data demonstrate that intelectin has molecular pattern binding activity characteristic of the innate immune system, in that it binds to carbohydrates found on a variety microbes - through interaction with exocyclic 1, 2 diols - but does not bind to host carbohydrates because of steric hindrance. Our preliminary data identify qualitative and quantitative aberrations of the two isoforms of intelectin (ITLN1 and ITLN2) in small intestinal specimens from individuals with ileal Crohn's disease (CD) compared to controls. While statistically significant, the mechanisms that may tie these changes to impaired innate immunity in CD are unknown and will be investigated. Our hypothesis, based on published and preliminary data, is that intelectin is a critical mediator of host-microbe interaction in the intestine. Aim 1 will determine the relative expression levels of ITLN1 and ITLN2 in small intestinal CD and control specimens, and biochemically characterize intelectin isolated from human small intestine. Aim 2 will investigate the in vitro activity of intelectin isoforms in vitro. Aim 3 will establish innate immunological consequences of intelectin expression using newly generated C57BL/6 Itln-/- mice. Our goal is to elucidate a fundamental understanding on the role of intelectin in mucosal protection, and in so doing, fill a void in our understanding of a conserved, highly abundant secretory protein of human Paneth cells. Successful completion of these studies will likely have broad impact on our mechanistic understanding of innate immunity in the small intestine.