The role of Paneth cell sirtuin 1 in intestinal tissue homeostasis and colorectal carcinogenesis.

项目摘要 结直肠癌（CRC）是世界上第三大确诊恶性肿瘤（1）。两倍多 所有病例和死亡都与可改变的环境风险因素有关（2）。尤其是CRC发病率 在更年轻的年龄（<50岁）增加（3）。因此，新的基于目标的方法， 需要确定遗传和环境因素来治疗这种肿瘤（4，5）。肠 上皮内环境稳定是由上皮细胞、肠道微生物和 免疫细胞（6，7）。这些协调的相互作用的破坏导致炎症性疾病，如 结肠炎和CRC。一种调节肠道上皮细胞、微生物群和 免疫细胞中最重要的是sirtuin 1（SIRT 1），它是高度保守的NAD+- 依赖性组蛋白脱乙酰酶和/或称为sirtuins的ADP-核糖基转移酶（8）。我们和其他人已经证明 肠上皮SIRT 1调节肠道应激反应和组织稳态， 因子导致肠道炎症，肠道微生物组成的破坏，以及对 《儿童权利公约》（9-13）。特别是，我们发现肠上皮SIRT 1的缺失导致了 潘氏细胞（Paneth cell）的过度活化（11），潘氏细胞是对肠道微生物群很重要的、由马槟榔碱产生的先天性免疫细胞 调节和肠道干细胞生态位维持（14）。最近，我们生成了一个Paneth细胞特异性SIRT 1 通过用Defa 6-Cre系繁殖SIRT 1 floxed等位基因的KO小鼠模型（SIRT 1 PKO）（15）， 表达潘氏细胞标志物，增加潘氏细胞数量，增强对化学物质的保护作用， 诱发炎症。 本研究将探讨SIRT 1在潘氏细胞中的作用，以及潘氏细胞中SIRT 1的缺乏如何影响 环境对肠上皮内环境稳定的影响。由于肠道微生物群在 宿主免疫系统（16）以及抗肿瘤免疫疗法的功效（17-20），其还将寻求 解析SIRT 1对肠道微生物组的调节，以及这种相互作用如何改变肠道和全身免疫 功能，其可影响抗肿瘤免疫和抗肿瘤免疫疗法的功效。因此，在本发明中， 了解SIRT 1在潘氏细胞背景下的肠上皮中的作用将有助于阐明 对潘氏细胞的破坏可导致肠道微生物组的变化，免疫功能的改变， 上皮内环境稳定 这项研究的目的是： 目的1：确定潘氏细胞中的SIRT 1缺失是否会破坏肠道微生物群并改变肠道免疫力。 目的2：探讨潘氏细胞中SIRT 1基因缺失是否影响抗肿瘤免疫。 目的3：研究Flox和PKO小鼠的抗肿瘤免疫差异是否影响抗肿瘤药物的疗效。 肿瘤免疫疗法

Project Summary Colorectal cancer (CRC) represents the third most diagnosed malignancy in the world (1). More than two-fold of all cases and deaths are associated with modifiable environmental risk factors (2). In particular, CRC incidence has been increasing at younger ages (<50 years) (3). Therefore, novel target-based approaches that link both genetic and environmental factors need to be established for the treatment of this neoplasm (4, 5). Intestinal epithelial homeostasis is maintained by a complex interplay between epithelial cells, gut microorganisms, and immune cells (6, 7). Disruptions of these orchestrated interactions results in inflammatory disorders such as colitis and CRC. One genetic factor that modulates the interactions between gut epithelium, microbiota and immune cells is sirtuin 1 (SIRT1), the most conserved mammalian member of a family of highly conserved NAD+- dependent histone deacetylases and/or ADP-ribosyltransferases called sirtuins (8). We and others have shown that intestinal epithelial SIRT1 regulates intestinal stress response and tissue homeostasis, deficiency of this factor leads to intestinal inflammation, disruption of gut microbial composition, and altered susceptibility to environmentally CRC (9-13). Particularly, we found that deletion of intestinal epithelial SIRT1 results in hyperactivation of Paneth cells (11), intestine-originated innate immune cells important for gut microbiota regulation and intestinal stem cell niche maintenance (14). Recently we generated a Paneth-cell specific SIRT1 KO mouse model (SIRT1 PKO) by breeding SIRT1 floxed allele with Defa6-Cre line (15), and found elevated expression of Paneth cell markers, increased Paneth cell number, and enhanced protection against chemical induced inflammation. This study will investigate the role of SIRT1 in Paneth cells and how deficiency of SIRT1 in Paneth cells impacts environmental influences on intestinal epithelial homeostasis. Since gut microbiota plays a fundamental role on the host immune system (16), as well as the efficacy of anti-tumor immunotherapies (17-20), it will also seek to parse out SIRT1 regulation of gut microbiome and how this interaction can alter intestinal and systemic immune function, which can impact anti-tumor immunity and the efficacy of anti-tumor immunotherapies. Thus, understanding the role of SIRT1 in intestinal epithelial in the context of Paneth cells will shed light on to how disruptions on Paneth cells can result in changes of gut microbiome, altered immune functions, and disrupts epithelial homeostasis. The aims of the study are: Aim 1: To determine if SIRT1 deletion in Paneth cells disrupts gut microbiota and alters gut immunity. Aim 2: To explore if SIRT1 deletion in Paneth Cells alters anti-tumor immunity. Aim 3: To investigate if the differential anti-tumor immunity in Flox and PKO mice affects the efficacy of anti- tumor immunotherapies.