PGD2 / DP1在克罗恩病肠壁纤维化中的作用及机制研究

In the absence of fibrosis-specific drugs, traditional anti-inflammatory therapies have not prevented or reduced the incidence of fibrosis in Crohn’s disease（CD）patients. About one third CD patients succumb to this complication, thus, a greater understanding the mechanisms that underlie the development of CD associated fibrosis has potential to identify new avenues for therapeutic intervention. Our previous findings indicated global and specific ablation of DP1 receptor in vascular endothelial cells, colonic epithelium and myeloid cells augmented DSS/TNBS -induced colitis in mice. Furthermore, DP1 deficiency significantly increased thickness of the bowel wall and excessive deposition of a collagen-containing extracellular matrix (ECM). To determine prostaglandin (PG) D2/ D prostanoid receptor 1(DP1) axis is required for intestinal fibrosis and stricture formation in CD via improving inflammatory response, in this study, we will utilize DP1 conditional knockout mice to build TNBS-induced murine CD model, and investigate the inhibitory roles of PGD2 / DP1 signal in CD associated fibrosis and potential molecular mechanism by using mass spectrometric analysis, flow cytometry，ChIP Sequencing, and so on. All of which would significantly improve the clinical management of IBD.

目前治疗克罗恩病（CD）的药物能够有效地抑制肠道的炎症反应，但抑制肠壁纤维化的发生效果不佳，大约1/3的CD患者在其病程中最终出现肠腔狭窄，因此，明确其肠壁纤维化发生的分子机制并寻找有效抑制纤维化的治疗靶点尤为重要。基于我们的DP1全身及细胞特异性敲除小鼠肠炎模型，前列腺素D2（PGD2）可以抑制DSS/TNBS诱导的结肠炎症反应，以及我们前期工作发现PGD2/DP1通路可抑制肠壁厚度及胶原的沉积，因此，我们推测PGD2/DP1通路可能通过调控炎症反应抑制CD肠壁纤维化。本项目在此基础上拟进一步采用DP1条件性敲除小鼠肠炎模型、质谱分析、流式细胞分析、ChIP Sequencing等技术，探索PGD2/DP1对炎症纤维化的抑制作用，阐明激活PGD2/DP1信号通路通过调控炎症反应抑制CD肠道纤维化发生及机制，为有效抑制CD肠壁纤维化的靶向治疗提供新的途经和理论依据。

肠纤维化是炎症性肠病患者不可避免的并发症，长期持续的炎症刺激、肌成纤维细胞过度激活和细胞外基质沉积导致肠纤维化的发生。前列腺素D是诱导炎症修复的介质，能够通过D-前列腺素受体1（DP1）改善IBD临床进展。然而，PGD2/DP1通路在CD相关性肠纤维化中的作用有待研究。利用葡聚糖硫酸钠（DSS）或2,4,6-三硝基苯磺酸（TNBS）在DP1基因敲除小鼠和野生型小鼠中诱导CD小鼠模型。通过IF、qRT PCR、IHC和WB研究DP1对小鼠肠纤维化中不同间充质细胞、细胞因子和上皮-间充质转化（EMT）的影响。通过RNA-seq分析寻找潜在的分子机制。研究结果显示DP1缺失通过增加ECM（尤其是I型胶原）的沉积和上皮细胞向肌成纤维细胞的分化，加剧DSS和TNBS诱导的小鼠的肠纤维化。RNA-seq分析表明，ECM受体相互作用和cAMP信号通路都属于前15个KEGG富集途径。此外，在两种小鼠模型中，Creb家族参与了其中2-3条共同途径，这表明其在介导肠纤维化反应中起关键作用。每天给小鼠注射DP1激动剂（BW245C；1mg/kg）可减轻WT小鼠CD相关的纤维化程度。在机制上，我们证明DP1通过cAMP/p-CREB/Slug信号抑制肌成纤维细胞激活，从而减轻肠纤维化。PGD2/DP1轴干扰slug的表达，并最终通过cAMP/PKA/p-CREB信号抑制肠上皮细胞向肌成纤维细胞分化，该信号通路对寻找特定的抗纤维化靶点用来治疗CD相关狭窄提供理论依据。相关文章题目为“Loss of DP1 Aggravates Intestinal Fibrosis in experimental inflammatory bowel disease via Slug-Mediated Myofibroblast Activation”准备投稿GUT等消化病顶尖杂志。题目为“Prediction of complications in inflammatory bowel disease using routine blood parameters at diagnosis”已投稿annual translational medicine 杂志，修回。另外，在Proliferation，Annual translational medicine杂志发表标注该项目资助的相关文章。