干预Notch信号通路调控胰腺内源性Krt5+干细胞分化对急性胰腺炎β细胞损伤后再生的作用及机制初探

Impaired glucose tolerance (IGT) and diabetes mellitus (DM) following acute pancreatitis (AP) are raising concerns. Notch signaling is a critical factor that determines whether pancreatic progenitors differentiating into endocrine or exocrine cells. Studies have demonstrated that Krt5 positive cell was the stem cell of lung, salivary gland for tissue regeneration after injury. The IGT and β cell injury have been observed in our previous work, only a few Krt5 positive cells were observed in normal pancreas, while the number increased more than 20 times in injured pancreatic tissues. Interestingly, we found that a few Krt5 positive stem cells differentiated into functional β cells, and partially compensated the dysfunction of β cells, but not reversed IGT and DM. Whether the differentiation of Krt5 positive stem cells into functional β cells following AP could be prompted by intervening Notch activity? Through intervening Notch activity with the use of Notch inhibitor, gene overexpression and silencing methods both in vitro and in vivo, as well as using human pancreatic specimens, this study will prove that the activity of Notch signaling is a critical factor regulating the differentiation of pancreatic endogenous Krt5 positive stem cells into functional β cells following AP. This study will also prove that inhibition of Notch signaling pathway in early stage of AP will prompt more Krt5 positive stem cells differentiating into functional β cells, thus offer a new approach for the prevention and treatment of IGT and DM following AP.

急性胰腺炎(AP)后糖耐量受损(IGT)及糖尿病(DM)逐渐引起关注。Notch信号是决定胰腺祖细胞向内、外分泌细胞分化的关键因素。有报道Krt5+细胞为肺和唾液腺损伤后再生的干细胞。本课题组前期在动物AP模型中观察到IGT及β细胞损伤，发现正常胰腺少有Krt5+干细胞且其在AP后增加超20倍，仅少数Krt5+干细胞分化为β细胞，不足以缓解AP后IGT及DM。那么，AP后干预Notch活性能否促使更多Krt5+干细胞向功能性β细胞分化？拟通过体内、离体培养Krt5+干细胞，分别以Notch抑制剂、基因沉默和过表达等干预，证实AP后Notch活性为调控Krt5+干细胞向β细胞分化的关键信号，探明AP后Krt5+干细胞的来源，并结合人体标本进一步证实Krt5+干细胞参与β细胞再生。明确AP早期抑制Notch活性，促使更多Krt5+干细胞分化为功能性β细胞，为防治AP后IGT及DM提供新途径。

急性胰腺炎(AP)后部分患者出现糖耐量受损(IGT)及糖尿病(DM)，其机制不明。Notch信号是决定胰腺祖细胞向内、外分泌细胞分化的关键因素。Krt5+细胞作为胰腺干细胞，在AP自然病程中极少数分化为胰岛β细胞，不足以代偿AP后IGT及DM。该项目的实施，充分证实了胰岛β细胞坏死和去分化为AP后IGT及DM的重要原因。人和小鼠AP时胰腺组织中大量Krt5+干细胞激活，伴Notch活性增高。体、内外实验证实了，抑制Notch信号通路，促使胰腺Krt5+干细胞分化为功能性胰岛β细胞。该项目的实施，明确了Notch信号通路可作为干预靶点，为AP后糖尿病新药的开发提供了理论基础。