Fang Xiao-Xia, Xu Fen-Fen, Liu Zhan, Cao Bei-Bei, Qiu Yi-Hua, Peng Yu-Ping
Department of Physiology, School of Medicine, and Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China.
Neural Regen Res. 2022 Dec;17(12):2771-2777. doi: 10.4103/1673-5374.339490.
Interleukin 17A (IL-17A) was previously shown to be a key pro-inflammatory factor in diabetes mellitus and associated complications. However, the role of IL-17A in diabetic encephalopathy remains poorly understood. In this study, we established a mouse model of diabetic encephalopathy that was deficient in IL-17A by crossing Il17a mice with spontaneously diabetic Ins2 (Akita) mice. Blood glucose levels and body weights were monitored from 2-32 weeks of age. When mice were 32 weeks of age, behavioral tests were performed, including a novel object recognition test for assessing short-term memory and learning and a Morris water maze test for evaluating hippocampus-dependent spatial learning and memory. IL-17A levels in the serum, cerebrospinal fluid, and hippocampus were detected with enzyme-linked immunosorbent assays and real-time quantitative polymerase chain reaction. Moreover, proteins related to cognitive dysfunction (amyloid precursor protein, β-amyloid cleavage enzyme 1, p-tau, and tau), apoptosis (caspase-3 and -9), inflammation (inducible nitric oxide synthase and cyclooxygenase 2), and occludin were detected by western blot assays. Pro-inflammatory cytokines including tumor necrosis factor-α, interleukin-1β, and interferon-γ in serum and hippocampal tissues were measured by enzyme-linked immunosorbent assays. Microglial activation and hippocampal neuronal apoptosis were detected by immunofluorescent staining. Compared with that in wild-type mice, mice with diabetic encephalopathy had higher IL-17A levels in the serum, cerebrospinal fluid, and hippocampus; downregulation of occludin expression; lower cognitive ability; greater loss of hippocampal neurons; increased microglial activation; and higher expression of inflammatory factors in the serum and hippocampus. IL-17A knockout attenuated the abovementioned changes in mice with diabetic encephalopathy. These findings suggest that IL-17A participates in the pathological process of diabetic encephalopathy. Furthermore, IL-17A deficiency reduces diabetic encephalopathy-mediated neuroinflammation and cognitive defects. These results highlight a role for IL-17A as a mediator of diabetic encephalopathy and potential target for the treatment of cognitive impairment induced by diabetic encephalopathy.
白细胞介素17A（IL-17A）先前被证明是糖尿病及其相关并发症中的关键促炎因子。然而，IL-17A在糖尿病性脑病中的作用仍知之甚少。在本研究中，我们通过将Il17a基因敲除小鼠与自发性糖尿病Ins2（Akita）小鼠杂交，建立了IL-17A缺陷的糖尿病性脑病小鼠模型。从2至32周龄监测血糖水平和体重。当小鼠32周龄时，进行行为测试，包括用于评估短期记忆和学习的新物体识别测试以及用于评估海马依赖性空间学习和记忆的莫里斯水迷宫测试。用酶联免疫吸附测定法和实时定量聚合酶链反应检测血清、脑脊液和海马中的IL-17A水平。此外，通过蛋白质印迹法检测与认知功能障碍相关的蛋白质（淀粉样前体蛋白、β淀粉样蛋白裂解酶1、磷酸化tau蛋白和tau蛋白）、凋亡相关蛋白（半胱天冬酶-3和-9）、炎症相关蛋白（诱导型一氧化氮合酶和环氧化酶2）以及闭锁蛋白。通过酶联免疫吸附测定法测量血清和海马组织中的促炎细胞因子，包括肿瘤坏死因子-α、白细胞介素-1β和干扰素-γ。通过免疫荧光染色检测小胶质细胞活化和海马神经元凋亡。与野生型小鼠相比，糖尿病性脑病小鼠血清、脑脊液和海马中的IL-17A水平更高；闭锁蛋白表达下调；认知能力较低；海马神经元损失更大；小胶质细胞活化增加；血清和海马中炎症因子表达更高。IL-17A基因敲除减轻了糖尿病性脑病小鼠的上述变化。这些发现表明IL-17A参与了糖尿病性脑病的病理过程。此外，IL-17A缺乏可减轻糖尿病性脑病介导的神经炎症和认知缺陷。这些结果突出了IL-17A作为糖尿病性脑病介质的作用以及作为治疗糖尿病性脑病所致认知障碍潜在靶点的作用。
