粘膜更新依赖于肠道干细胞（ISC）的活性，是粘膜修复的基础。重要的是，储备 ISC (rISC) 的激活在损伤后启动粘膜修复中起着至关重要的作用。然而，鸡 rISC 激活的潜在调控机制仍不清楚。在这项研究中，脂多糖 (LPS) 攻击后，隐窝中立即出现线粒体形态破坏和功能障碍，并伴有上皮分泌减少（Muc2 mRNA 丰度和 LYSOZYME 蛋白水平降低）。然而，粘膜损伤后，粘膜更新加速，BrdU 阳性率、增殖细胞核抗原 (PCNA) 蛋白水平和细胞周期标志物 (Ccnd1、Cdk2) mRNA 丰度增加表明。关于ISCs活性，在损伤早期，出现活性ISCs（aISCs）标志物Lgr5 mRNA和蛋白的减少，以及rISCs标志物Hopx mRNA和蛋白的增加。引人注目的是，在 LPS 攻击后，在隐窝中检测到 Krüppel 样因子 5 (Klf5) 的 mRNA 转录水平增加。此外，在类器官LPS处理下，KLF5抑制剂（ML264）会降低Stat5a和Hopx的mRNA和蛋白质水平，STAT5A抑制剂（AC-4-130）会抑制Lgr5 mRNA和蛋白质水平。此外，双荧光素酶报告基因测定证实，KLF5会结合Hopx启动子并激活rISC，STAT5A会触发Lgr5启动子并激活aISC。总的来说，KLF5在损伤早期表达上调，进一步直接激活rISC，并通过STAT5A间接激活aISC，从而启动损伤后的粘膜修复。

The mucosal renewal, which depends on the intestinal stem cell (ISC) activity, is the foundation of mucosal repairment. Importantly, activation of reserve ISCs (rISCs) plays a vital role in initiating mucosal repair after injury. However, the underlying regulatory mechanism of rISCs activation in chickens remains unclear. In this study, immediately after lipopolysaccharide (LPS) challenge, mitochondrial morphological destruction and dysfunction appeared in the crypt, accompanied by decreased epithelial secretion (decreased Muc2 mRNA abundance and LYSOZYME protein level). However, immediately after mucosal injury, the mucosal renewal accelerated, as indicated by the increased BrdU positive rate, proliferating cell nuclear antigen (PCNA) protein level and mRNA abundance of cell cycle markers (Ccnd1, Cdk2). Concerning the ISCs activity, during the early period of injury, there appeared a reduction of active ISCs (aISCs) marker Lgr5 mRNA and protein, and an increasing of rISCs marker Hopx mRNA and protein. Strikingly, upon LPS challenge, increased mRNA transcriptional level of Krüppel-like factor 5 (Klf5) was detected in the crypt. Moreover, under LPS treatment in organoids, the KLF5 inhibitor (ML264) would decrease the mRNA and protein levels of Stat5a and Hopx, the STAT5A inhibitor (AC-4-130) would suppress the Lgr5 mRNA and protein levels. Furthermore, the Dual-Luciferase Reporter assay confirmed that, KLF5 would bind to Hopx promoter and activate the rISCs, STAT5A would trigger Lgr5 promoter and activate the aISCs. Collectively, KLF5 was upregulated during the early period of injury, further activate the rISCs directly and activate aISCs via STAT5A indirectly, thus initiate mucosal repair after injury.