α7nAChR的激活通过抑制TNF-α表达促进糖尿病小鼠伤口愈合

 目的：观察糖尿病小鼠伤口愈合期间巨噬细胞浸润及肿瘤坏死因子 α（TNF-α）表达特征，探讨α7烟碱型乙酰胆碱受体（α7nAChR）特异性激动剂PNU-282987是否可通过抑制TNF-α表达促进糖尿病小鼠伤口的愈合。方法：(1) 制作糖尿病小鼠切创模型（糖尿病组），正常小鼠在相同部位制作相同大小创口作为对照（对照组），分别于切创后1 d、3 d、5 d、10 d、14 d和21 d（每个时间段5只）提取创口样本。免疫组化观察创口中巨噬细胞和成纤维细胞数量，Western blotting检测TNF-α表达水平，Masson染色观察胶原沉积情况。 (2) 在糖尿病小鼠切创后，选择合适的干预时间窗进行PNU-282987干预，然后观察上述指标变化。结果：(1) 与对照组相比，糖尿病组创口愈合明显延迟，在切创初期的伤口中巨噬细胞数量和TNF-α表达水平较低（P<0.05），而切创5 d后的伤口巨噬细胞数量和TNF-α表达水平显著增加（P<0.05），成纤维细胞数量和胶原含量减少（P<0.05）。 (2) 在切创5 d后对糖尿病小鼠腹腔注射PNU-282987，可显著减少伤口中TNF-α表达，提高成纤维细胞数量和胶原含量，促进伤口愈合。结论：糖尿病伤口愈合具有炎症反应发生迟但不易消退的特征。在炎症反应明显期激活α7nAChR可抑制TNF-α表达，促进糖尿病小鼠的伤口愈合。

Activation of a7nAChR promotes wound healing in diabetic mice by suppressing TNF-a expression

AIM: To explore the role of α7 nicotinic acetylcholine receptor (α7nAChR)-specific agonist PNU-282987 in promoting wound healing in diabetic mice by suppressing the expression of tumor necrosis factor α （TNF-α）.METHODS: A model of incised wound was established in diabetic mice or normoglycaemic mice (control). Skin samples were taken on 1 d, 3 d, 5 d, 10 d, 14 d and 21 d post-injury (5 mice in each posttraumatic interval). The numbers of macrophages and fibroblasts, the expression of TNF-α and the deposition of collagen were detected by the methods of immunohistochemistry, Western blotting and Masson staining, respectively. After incised wound was performed in the diabetic mice, PNU-282987 was applied by intraperitoneal injection at suitable posttraumatic interval. The above indexes were investigated again.RESULTS: Compared with control group, the diabetic mice presented delayed wound healing. In diabe-tic mice, the infiltration of macrophages and the expression of TNF-α were significantly reduced in the early phase during wound healing, while they were significantly increased from 5 d post-injury. Besides, from 5 d to 21 d post-injury, the wounds in diabetic mice showed decreased number of fibroblasts and deposition of collagen. From 5 d post-injury, PNU-282987 was applied to diabetic mice, which significantly down-regulated the expression of TNF-α, and increased the number of fibroblasts and the content of collagen in the wounds, eventually promoted wound healing.CONCLUSION: Inflammatory reactions delay wound healing in diabetic mice. Activation of α7nAChR promotes wound healing in diabetic mice by suppressing the expression of TNF-α.