Department of Medicine II, Division of Gastroenterology, University of Rostock, Rostock, Germany.
J Cell Mol Med. 2012 Nov;16(11):2620-30. doi: 10.1111/j.1582-4934.2012.01573.x.
In chronic pancreatitis (CP), persistent activation of pancreatic stellate cells (PSC) converts wound healing into a pathological process resulting in organ fibrosis. Here, we have analysed senescence as a novel mechanism involved in the termination of PSC activation and tissue repair. PSC senescence was first studied in vitro by establishing long-term cultures and by applying chemical triggers, using senescence-associated β-Galactosidase (SA β-Gal) as a surrogate marker. Subsequently, susceptibility of PSC to immune cell-mediated cytolysis was investigated employing cocultures. Using the model of dibutyltin dichloride-induced CP in rats, appearance of senescent cells was monitored by immunohistochemistry and immunofluorescence, and correlated with the progression of tissue damage and repair, immune cell infiltration and fibrosis. The results indicated that long-term culture and exposure of PSC to stressors (doxorubicin, H(2) O(2) and staurosporine) induced senescence. Senescent PSC highly expressed CDKN1A/p21, mdm2 and interleukin (IL)-6, but displayed low levels of α-smooth muscle actin. Senescence increased the susceptibility of PSC to cytolysis. In CP, the number of senescent cells correlated with the severity of inflammation and the extension of fibrosis. Areas staining positive for SA β-Gal overlapped with regions of fibrosis and dense infiltrates of immune cells. Furthermore, a close physical proximity of immune cells and activated PSC was observed. We conclude that inflammation, PSC activation and cellular senescence are timely coupled processes which take place in the same microenvironment of the inflamed pancreas. Lymphocytes may play a dual-specific role in pancreatic fibrogenesis, triggering both the initiation of wound healing by activating PSC, and its completion by killing senescent stellate cells.
在慢性胰腺炎（CP）中，胰腺星状细胞（PSC）的持续激活将创伤愈合转化为导致器官纤维化的病理性过程。在这里，我们分析了衰老作为一种新的机制，参与PSC 激活和组织修复的终止。PSC 衰老首先通过建立长期培养物并应用化学触发物在体外进行研究，使用衰老相关β-半乳糖苷酶（SA β-Gal）作为替代标志物。随后，通过共培养研究了 PSC 对免疫细胞介导的细胞溶解的易感性。使用二丁基锡二氯化物诱导的大鼠 CP 模型，通过免疫组织化学和免疫荧光监测衰老细胞的出现，并将其与组织损伤和修复、免疫细胞浸润和纤维化的进展相关联。结果表明，长期培养和 PSC 暴露于应激源（阿霉素、H₂O₂和司他丁）会诱导衰老。衰老的 PSC 高度表达 CDKN1A/p21、mdm2 和白细胞介素（IL）-6，但α-平滑肌肌动蛋白水平较低。衰老增加了 PSC 对细胞溶解的易感性。在 CP 中，衰老细胞的数量与炎症的严重程度和纤维化的扩展相关。SA β-Gal 染色阳性的区域与纤维化和免疫细胞密集浸润的区域重叠。此外，观察到免疫细胞和激活的 PSC 之间存在紧密的物理接近。我们得出结论，炎症、PSC 激活和细胞衰老都是发生在炎症胰腺相同微环境中的及时偶联过程。淋巴细胞在胰腺纤维化的发生中可能具有双重特异性作用，通过激活 PSC 触发创伤愈合的启动，并通过杀死衰老的星状细胞完成愈合。
