Division of Gastroenterology and Hepatology, Stanford University School of Medicine, Stanford, California.
Cedars-Sinai Medical Center and Department of Veterans Affairs, Los Angeles, California.
Gastroenterology. 2018 May;154(6):1822-1835.e2. doi: 10.1053/j.gastro.2018.01.065. Epub 2018 Feb 6.
BACKGROUND & AIMS: Acute pancreatitis (AP) is characterized by severe inflammation and acinar cell death. Transmembrane protein 173 (TMEM173 or STING) is a DNA sensor adaptor protein on immune cells that recognizes cytosolic nucleic acids and transmits signals that activate production of interferons and the innate immune response. We investigated whether leukocyte STING signaling mediates inflammation in mice with AP.
We induced AP in C57BL/6J mice (control) and C57BL/6J-Tmem173gt/J mice (STING-knockout mice) by injection of cerulein or placement on choline-deficient DL-ethionine supplemented diet. In some mice, STING signaling was induced by administration of a pharmacologic agonist. AP was also induced in C57BL/6J mice with bone marrow transplants from control or STING-knockout mice and in mice with disruption of the cyclic GMP-AMP synthase (Cgas) gene. Pancreata were collected, analyzed by histology, and acini were isolated and analyzed by flow cytometry, quantitative polymerase chain reaction, immunoblots, and enzyme-linked immunosorbent assay. Bone-marrow-derived macrophages were collected from mice and tested for their ability to detect DNA from dying acinar cells in the presence and absence of deoxyribonuclease (DNaseI).
STING signaling was activated in pancreata from mice with AP but not mice without AP. STING-knockout mice developed less severe AP (less edema, inflammation, and markers of pancreatic injury) than control mice, whereas mice given a STING agonist developed more severe AP than controls. In immune cells collected from pancreata, STING was expressed predominantly in macrophages. Levels of cGAS were increased in mice with vs without AP, and cGAS-knockout mice had decreased edema, inflammation, and other markers of pancreatic injury upon induction of AP than control mice. Wild-type mice given bone marrow transplants from STING-knockout mice had less pancreatic injury and lower serum levels of lipase and pancreatic trypsin activity following induction of AP than mice given wild-type bone marrow. DNA from dying acinar cells activated STING signaling in macrophages, which was inhibited by addition of DNaseI.
In mice with AP, STING senses acinar cell death (by detecting DNA from dying acinar cells) and activates a signaling pathway that promotes inflammation. Macrophages express STING and activate pancreatic inflammation in AP.
急性胰腺炎（AP）的特征为严重炎症和腺泡细胞死亡。跨膜蛋白 173（TMEM173 或 STING）是一种免疫细胞上的 DNA 传感器衔接蛋白，可识别细胞溶质核酸并传递信号，激活干扰素和先天免疫反应的产生。我们研究了白细胞 STING 信号是否介导 AP 小鼠的炎症。
我们通过注射 cerulein 或放置在胆碱缺乏的 DL-蛋氨酸补充饮食上来诱导 C57BL/6J 小鼠（对照组）和 C57BL/6J-Tmem173gt/J 小鼠（STING 敲除小鼠）发生 AP。在一些小鼠中，通过给予药理学激动剂诱导 STING 信号。我们还通过来自对照组或 STING 敲除小鼠的骨髓移植在 C57BL/6J 小鼠中诱导 AP，并在环鸟苷酸-腺苷酸合酶（Cgas）基因缺失的小鼠中诱导 AP。收集胰腺，通过组织学分析，分离和分析腺泡细胞，并通过定量聚合酶链反应、免疫印迹和酶联免疫吸附试验进行分析。从小鼠中收集骨髓衍生的巨噬细胞，并在存在和不存在脱氧核糖核酸酶（DNaseI）的情况下检测来自死亡腺泡细胞的 DNA 的能力进行测试。
AP 小鼠的胰腺中激活了 STING 信号，但无 AP 小鼠则没有。与对照组相比，STING 敲除小鼠发生的 AP 较轻（水肿、炎症和胰腺损伤标志物较少），而给予 STING 激动剂的小鼠发生的 AP 较对照组严重。在从胰腺中收集的免疫细胞中，STING 主要在巨噬细胞中表达。与无 AP 相比，AP 小鼠的 cGAS 水平升高，并且 cGAS 敲除小鼠在诱导 AP 后，与对照组相比，水肿、炎症和其他胰腺损伤标志物减少。给予来自 STING 敲除小鼠的骨髓移植的野生型小鼠在诱导 AP 后，与给予野生型骨髓的小鼠相比，胰腺损伤减少，血清脂肪酶和胰腺胰蛋白酶活性降低。来自死亡腺泡细胞的 DNA 激活了巨噬细胞中的 STING 信号，该信号通过添加 DNaseI 而被抑制。
在 AP 小鼠中，STING 感知腺泡细胞死亡（通过检测来自死亡腺泡细胞的 DNA）并激活促进炎症的信号通路。巨噬细胞表达 STING 并在 AP 中激活胰腺炎症。
