Wang Lei, Zhao Jing, Zhu Baofeng, Shen Junhua, Ye Zi, Peng Qiang, Zhang Yi
Department of Emergency Center, Affiliated Hospital 2 of Nantong University, Nantong, Jiangsu, China.
Department of Dermatology, Affiliated Hospital 3 of Nantong University, Nantong, Jiangsu, China.
Arch Med Sci. 2021 Mar 25;20(4):1307-1313. doi: 10.5114/aoms/116550. eCollection 2024.
In the occurrence and development of heat stroke (HS), factors such as hyperthermia, ischemia and hypoxia are essential to the central nervous system (CNS) inflammatory response, but the main mechanism underlying CNS inflammation remains unclear. The aim of the study was to observe the polarization of microglia in response to heat-induced early nerve injury and to explore its possible mechanism of action.
To establish a heatstroke animal model in Beagle dogs, 18 Beagle dogs were divided into control (group A) and experimental groups (group B, group C and group D) according to a random numbers table. The animals in the experimental groups were placed on an electric blanket of an animal body temperature maintaining apparatus. The temperature was set at 40 ±0.5°C, and the rectal temperature was monitored every 5 min until the target body temperature was reached. Once the target temperature was reached, the dogs were transferred to an environment of 26 ±0.5°C and 60 ±0.5% humidity. Western blot analysis was used to detect the expression of microglia-specific markers CD45, iNOS, arginase, and CD206 in normal and heat-damaged brain tissues at different time points (1 h, 6 h, 24 h). The expression of CD45 and arginase was further determined by co-localization with immunofluorescence.
CD45 and iNOS protein expression was detected in group A. The two protein markers in group B were significantly higher than those in group A ( < 0.05), and the protein markers in group C were still higher than those in group A ( < 0.05). There was no statistically significant difference among the animals in group A ( > 0.05). Arginase and CD206 protein expression was also detected in group A. Levels of the two protein markers in group B were higher than those in group A ( < 0.05), and the protein marker levels in group C were even higher than those in group A ( < 0.05). Further analysis of the two groups of protein markers in group D showed significantly higher levels than those in group A ( < 0.001). Immunofluorescence co-localization of CD45 and arginase showed significantly increased fluorescence density at 6 h and 24 h after thermal injury ( < 0.001).
After heat-induced disease, microglia were found to be active in the brain tissues of dogs. The microglia activated in the early 1-6 h of CNS injury were mainly the M1 type, which were then converted to the M2 type after 6 h. The 24 h M2 type was dominant. The relationship between M1/M2 polarization trends and early brain injury in heat-induced disease may be a key to understanding CNS injury in heat-induced disease.
在中暑（HS）的发生和发展过程中，高热、缺血和缺氧等因素对中枢神经系统（CNS）炎症反应至关重要，但CNS炎症的主要机制仍不清楚。本研究的目的是观察小胶质细胞对热诱导早期神经损伤的极化情况，并探讨其可能的作用机制。
为建立比格犬中暑动物模型，将18只比格犬根据随机数字表分为对照组（A组）和实验组（B组、C组和D组）。实验组动物置于动物体温维持装置的电热毯上。温度设定为40±0.5°C，每5分钟监测一次直肠温度，直至达到目标体温。一旦达到目标温度，将犬转移至温度为26±0.5°C、湿度为60±0.5%的环境中。采用蛋白质免疫印迹法检测不同时间点（1小时、6小时、24小时）正常和热损伤脑组织中小胶质细胞特异性标志物CD45、诱导型一氧化氮合酶（iNOS）、精氨酸酶和CD206的表达。通过免疫荧光共定位进一步测定CD45和精氨酸酶的表达。
A组检测到CD45和iNOS蛋白表达。B组的这两种蛋白标志物显著高于A组（P<0.05），C组的蛋白标志物仍高于A组（P<0.05）。A组动物之间无统计学显著差异（P>0.05）。A组也检测到精氨酸酶和CD206蛋白表达。B组的这两种蛋白标志物水平高于A组（P<0.05），C组的蛋白标志物水平甚至高于A组（P<0.05）。对D组两组蛋白标志物的进一步分析显示，其水平显著高于A组（P<0.001）。CD45和精氨酸酶的免疫荧光共定位显示，热损伤后6小时和24小时荧光密度显著增加（P<0.001）。
热诱导疾病后，发现比格犬脑组织中的小胶质细胞具有活性。在CNS损伤早期1 - 6小时激活的小胶质细胞主要为M1型，6小时后转变为M2型。24小时时M2型占主导。M1/M2极化趋势与热诱导疾病早期脑损伤之间的关系可能是理解热诱导疾病中CNS损伤的关键。
