重症中暑大鼠肾损伤与炎症反应的关系

Correlation of kidney injury and inflammatory response in rats with classic severe heatstroke

目的：探讨重症中暑（SHS）大鼠肾脏损伤的时程变化特点及与炎症反应的关系。方法雄性Wistar大鼠56只，按随机数字表法分为正常对照组和中暑0、2、6、24、48、72 h组7组，每组8只。中暑组将大鼠置于仿真高温气候舱内〔温度（39.5±0.2）℃，湿度（60±5）%〕，复制经典型SHS模型，以大鼠收缩压（SBP）峰值开始下降为模型成功标志，随后转至（23.0±0.2）℃室温下复温；正常对照组大鼠一直置于（23.0±0.2）℃室温下。于复温后各时间点取心脏血和肾组织，采用自动生化分析仪检测血清肌酐（SCr）、尿素氮（BUN）；酶联免疫吸附试验（ELISA）检测肾组织髓过氧化物酶（MPO）、肿瘤坏死因子-α（TNF-α）、白细胞介素-6（IL-6），以相对于正常对照组的百分比表示；光镜下观察肾组织病理学改变并进行肾损伤组织学评分（Paller评分）。结果与正常对照组比较，中暑6 h组大鼠血清SCr、 BUN和肾组织MPO、 TNF-α、IL-6水平即显著升高〔SCr（μmol/L）：174.0±27.0比68.0±11.3，BUN（mmol/L）：12.6±2.3比4.3±1.2，MPO：（203.0±38.0）%比（100.0±1.4）%，TNF-α：（121.0±16.0）%比（100.0±1.4）%，IL-6：（118.0±19.0）%比（100.0±1.3）%，均P＜0.05〕，24 h时达峰值〔SCr（μmol/L）：489.0±96.0比68.0±11.3，BUN（mmol/L）：19.3±5.7比4.3±1.2，MPO：（511.0±41.0）%比（100.0±1.4）%，TNF-α：（399.0±47.0）%比（100.0±1.4）%， IL-6：（473.0±56.0）%比（100.0±1.3）%，均P＜0.01〕，72 h时恢复正常水平。光镜下观察，大鼠中暑后肾脏即出现炎性细胞浸润、组织水肿及肾小管坏死等改变，24 h最为明显，之后逐渐恢复，至72 h接近正常；Paller评分于6 h时即较正常对照组明显升高（分：75.45±9.70比14.23±3.26，P＜0.01），24 h达峰值（分：186.00±14.25比14.23±3.26，P＜0.01），之后逐渐降低，72 h恢复正常。结论 SHS大鼠24 h内出现进行性肾损伤，与肾组织MPO、TNF-α、IL-6水平密切相关，提示抑制中性粒细胞激活以及IL-6、TNF-α释放可以保护SHS相关肾损伤。

ObjectiveTo investigate the temporal features of renal injury in rats with severe heat stroke （SHS） and their relationship with inflammatory response.Methods Fifty-six male Wistar rats were randomly divided into normal control group and SHS for 0, 2, 6, 24, 48, 72 hours group （SHS-0, 2, 6, 24, 48, 72 h groups）, with 8 rats in each group. Rats were placed in an artificial climate chamber [temperature （39.5±0.2）℃, humidity （60±5）%] to induce SHS model, and the criterion for successful model reproduction was the onset of lowering peak systolic blood pressure （SBP）. Then the rats were transferred to room temperature （23.0±0.2）℃ after successful reproduction of the model. The rats of normal control group were kept in room temperature of （23.0±0.2）℃. Heart blood and renal tissue samples were harvested, and the levels of serum creatinine （SCr） and blood urea nitrogen （BUN） were determined by automatic biochemistry analyzer. The levels of myeloperoxidase （MPO）, tumor necrosis factor-α（TNF-α） and interleukin-6 （IL-6） in renal tissue specimens were determined by enzyme linked immunosorbent assay （ELISA）. The changes in histopathology in kidney were observed with light microscopy, and Paller scores were used to assess the degree of renal injury.Results Compared with normal control group, the levels of SCr and BUN in serum, and MPO, TNF-α and IL-6 in the renal tissue homogenate were significantly increased in SHS-6 h group [SCr （μmol/L）： 174.0±27.0 vs.68.0±11.3, BUN （mmol/L）： 12.6±2.3 vs. 4.3±1.2, MPO： （203.0±38.0）% vs. （100.0±1.4）%, TNF-α： （121.0±16.0）% vs. （100.0±1.4）%, IL-6： （118.0±19.0）% vs. （100.0±1.3）%, allP〈0.05], and they peaked at 24 hours [SCr （μmol/L）： 489.0±96.0 vs. 68.0±11.3, BUN （mmol/L）： 19.3±5.7 vs. 4.3±1.2, MPO： （511.0±41.0）% vs. （100.0± 1.4）%, TNF-α： （399.0±47.0）% vs. （100.0±1.4）%, IL-6： （473.0±56.0）% vs. （100.0±1.3）%, allP〈0.01], then declined to the normal levels at 72 hours. Under light microscopy, tissue edema and necrosis of renal tubules were found, and leukocyte infiltration was found to be most profuse at 24 hours, then they returned to normal levels at 72 hours. Paller scores in SHS-6 h group were significantly higher than those of the normal control group （75.45±9.70 vs. 14.23±3.26,P〈0.01）, and it peaked at 24 hours （186.00±14.25 vs. 14.23±3.26,P〈0.01）, followed by a gradual lowering, back to normal level at 72 hours.ConclusionThe results suggest that progressive renal damage occurred in the rats with SHS within 24 hours, and it was accompanied with elevated levels of MPO, TNF-α and IL-6 in the kidney homogenate, suggesting that inhibition of neutrophil activation and the release of IL-6, TNF-α may protect the SHS associated renal injury.