胰腺生物钟Stabilizing Loop 调控慢性胰腺炎纤维化进程的作用及分子机制

Currently, it is unclear how pancreatic fibrogenesis is initiated and progressed in human chronic pancreatitis (CP). As an important peripheral oscillator, the roles for the pancreatic clock in the development of endocrine and exocrine disorders have drawn much attention recently. We previously demonstrated that rhythmic expression of the Stabilizing Loop of pancreatic clockwork was disrupted in CP patients and animal models, as well as in activated pancreatic stellate cells (PSCs). Pancreas-specific knockout of Bmal1, the core component of circadian transcription-translation feedback loops (TTFLs), led to significant spontaneous pancreatic fibrosis in mice. Given that the disbalance of PSC activation and transformation is a key factor for CP fibrogenesis, we thus speculate that continuous PSC activation resulting from dysregulation of the pancreatic Stabilizing Loop plays a pivotal role in the pathogenesis of CP fibrosis. In this study, we aim to clarify the relevance between pancreatic clock misalignment and CP development by clinical investigations and experimental animal studies; to elucidate the mechanism of aberrant pancreatic Stabilizing Loop expression in CP and the mechanism by which the TTFL regulates PSC transdifferentiation using molecular biological methods, both in vitro and in vivo; and to explore the therapeutic potential of melatonin in anti-CP fibrosis through restoring homeostasis of the Stabilizing Loop and pancreatic oscillation. Our work will help unravel the pathogenesis of chronic pancreatic fibrosis and may provide novel insights into the clinical management of CP.

目前慢性胰腺炎（CP）纤维化发生发展的机制尚未完全阐明；而胰腺作为重要的外周节律器官，其生物钟与内外分泌部疾病的关联倍受关注。我们前期研究发现CP病人和动物模型纤维化胰腺组织、胰腺星状细胞（PSC）活化过程中均存在生物钟Stabilizing Loop的异常表达及节律紊乱；其核心元件Bmal1基因胰腺特异性敲除的小鼠具有自发性胰腺纤维化倾向。因PSC活化与转归失衡是纤维化的促进因素，故此推测胰腺生物钟Stabilizing Loop紊乱介导的PSC持续活化在CP纤维化进程中发挥重要作用。我们拟通过临床病例调查、敲基因小鼠疾病模型研究胰腺生物钟紊乱与CP的关联及其临床意义；以体内外实验阐明CP时Stabilizing Loop紊乱的原因及其调控PSC转分化的分子机制；采用褪黑素干预探讨重置胰腺Stabilizing Loop在CP纤维化中的治疗价值。本研究的完成将为CP临床诊疗开辟全新途径。

生物钟是人体内环境的重要调控机制，胰腺作为重要的外周节律器官，其内外分泌部生理过程均受到生物钟的密切调控。慢性胰腺炎（CP）以进行性纤维化和外分泌失调为病理特点，其发生发展机制不明。结合我们前期发现的CP病人和动物模型纤维化胰腺组织、胰腺星状细胞（PSC）活化过程中均存在生物钟Stabilizing Loop （Rora/Nr1d1/Bmal1）的异常表达及节律紊乱，我们在本课题中进一步通过临床病理、动物模型、细胞分子机制等多个层面，对生物钟在CP中的作用、机制及干预方式进行系统性研究。我们发现胰腺生物钟在CP纤维化进程中发挥重要作用，Bmal1表达异常与CP患者临床表现有密切相关性。通过使用不同内源性（基因突变/敲除）和外源性（间歇禁食模型）生物钟紊乱的CP小鼠模型，我们发现胰腺原位生物钟在CP病理中较中枢生物钟发挥更重要的作用。进一步的实验室研究证明胰腺Bmal1缺失/下调是促进纤维化的关键因素，其通过TGF-E-cad轴调控PSC的活化，并通过IL-11旁分泌介导调控腺泡细胞的功能。在PSC活化过程中，细胞内脂滴的丢失诱导的Nr1d1反应性升高诱导生物钟Stabilizing Loop紊乱导致了Bmal1失表达。最后，我们筛查并测试了不同Stabilizing Loop靶向小分子药物的体外、体内作用，发现褪黑素(Me)l联合Rora小分子激动剂SR1078的治疗方案可以有效恢复胰腺生物钟节律，并抑制纤维化进展、减轻外分泌功能损伤。本研究的完成证明靶向胰腺生物钟/Stabilizing Loop的策略具有极大临床转化价值，或可成为CP诊疗的全新途径。