抗菌肽cathelicidins在维持肠道免疫稳态及1型糖尿病发病中的作用研究

In type 1 diabetes (T1D)-prone individuals, enteric bacterial pathogen-induced disruption of intestinal immune and barrier homeostasis is closely related to the pathogenesis of T1D. Our earlier studies have shown that the cathelicidin antimicrobial peptide induces modulatory immune responses in pancreatic islets. The current study aims to investigate the modulatory role and mechanisms of cathelicidins in Citrobacter rodentium (C. rodentium) infection-induced intestinal mucosal immune dysregulation and resultant acceleration of T1D. Firstly in cathelicidin-deficient cnlp-/- and wildtype mice, the modulatory effects of cathelicidins on intestinal immunity particularly CD8+ T cells, Treg and DC phenotypes and functional responses as well as on barrier integrity during C. rodentium infection will be studied; Subsequently in cnlp-/- NOD mice, the role of cathelicidins in maintaining intestinal barrier, T cell trafficking and islet immune homeostasis, thereby protecting against C. rodentium-induced T1D will be clarified; Lastly by lentiviral mediated knockdown and overexpression of signaling proteins, cellular and molecular mechanism by which cathelicidins act via its specific receptor(s) to negatively regulate C. rodentium-induced disruption of intestinal immune barrier and acceleration of T1D will be elucidated. The current study emphasizes maintenance of intestinal immune and barrier homeostasis in protecting the development of T1D. It will shed lights on new therapeutic strategies on T1D intervention.

在1型糖尿病（T1D）易感个体中，致病菌感染致肠道免疫稳态失衡与T1D发病密切相关；前期研究表明cathelicidins在调节胰岛免疫炎症中起积极作用。本项目拟探讨cathelicidins在致病菌（C. rodentium）感染引起肠道免疫稳态失衡致T1D发病中作用及机制：1) 在cathelicidin敲除（cnlp-/-）小鼠中，明确cathelicidins对致病菌感染引起肠道免疫稳态失衡中CD8+T，Treg，DC等表型和功能调控作用；2) 在cnlp-/- NOD小鼠中，阐明cathelicidins对致病菌诱导肠道免疫稳态失衡致T细胞迁移、T1D发病的作用；3)结合慢病毒沉默/过表达技术，明确cathelicidins通过确切受体调控SOCS-1和/或SOCS-3，促使TRAF-6和/或Mal泛素化从而抑制致病菌引起肠道免疫稳态失衡及T1D发病的分子机制。

在1型糖尿病（T1D）易感个体中，致病菌感染致肠道免疫稳态失衡与T1D发病密切相关；前期研究表明cathelicidins在调节胰岛免疫炎症防治实验型T1D中起积极作用。本项目拟探讨cathelicidins在致病菌（C. rodentium）感染引起肠道免疫稳态失衡致T1D发病中作用及机制：我们研究发现肠道中抗菌肽CRAMP水平与Citrobacter rodentium加速的自发性T1D或STZ诱导的T1D发病呈显著负相关。而CRAMP-/-鼠中，Citrobacter rodentium加速T1D更为显著并伴有明显的肠道功能紊乱，而Citrobacter rodentium加速T1D和肠道功能紊乱可被外源性CRAMP所缓解。进一步研究表明，CRAMP能够调节肠道微环境而维持肠道功能稳态并能够抑制肠道源性IFN-γ+T细胞（Tc1, Th1）向胰腺迁移，从而在胰腺产生耐受性胰腺免疫环境；最后，CRAMP还能够恢复Citrobacter rodentium引起的肠道菌群紊乱从而抑制MyD88信号通路，从而保护肠道屏障功能以及肠道-胰腺免疫微环境稳态。总的来说，CRAMP能够通过改善肠道稳态缓解Citrobacter rodentium加速的T1D发病；