高迁移率族蛋白1对内毒素急性肺损伤大鼠中性粒细胞凋亡改变的影响

目的 观察体外高迁移率族蛋白1（HMGB1）对内毒素急性肺损伤（ALI）大鼠中性粒细胞（PMN）凋亡改变的影响，以探讨HMGB1在ALI发病机制中的作用。方法 脂多糖注射复制大鼠急性肺损伤模型，在LPS致伤后不同时相点（有或无正丁酸钠干预时）获取肺组织、外周血中性粒细胞（PMN）、支气管肺泡灌洗液（BALF）。RT-PCR检测肺组织HMGB1 mRNA表达，流式细胞术（FCM）、Giemsa染色及TUNEL法检测PMN的凋亡改变。结果 与对照组比较，LPS急性肺损伤大鼠PMN凋亡率逐渐减低，鼠BALF中PMN凋亡开始时间及无存活细胞时间明显延长；LPS致伤后6-24h肺组织HMGB1 mRNA表达明显增高。正丁酸钠（SB）处理组动物肺组织于伤后6、12h肺组织HMGB1 mRNA表达均显著抑制，与LPS组比较，差异有显著性意义（P〈0．05）；形态学检查显示，LPS致伤后大鼠肺组织出现水肿及明显的病理变化，SB干预可减轻肺损伤的严重程度。致伤后肺损伤程度与肺组织HMGB1表达水平及PMN凋亡改变有关。结论 LPS致伤后，鼠肺HMGB1 mRNA高表达发生较晚，但持续较长时间；SB处理可削弱LPS诱导的PMN凋亡延迟及抑制，下调肺组织HMGB1 mRNA表达。HMGB1可能参与内毒素急性肺损伤时PMN的凋亡延迟及抑制效应。

Effects of high mobility group box 1 on apoptosis of polymorphonuclear granulocytes in LPS-induced acute lung injury in rats

Objective To observe the effects of high mobility group box 1 (HMGB1) on apoptosis of polymorphonuclear granulocytes (PMN) in LPS-induced acute lung injury (ALI) in rats, for clarifying the role of HMGB1 in the pathogenesis of acute lung injury. Methods Rat model of LPS-induced acute lung injury was constructed by LPS infusion. After LPS challenge in the presence or absence of sodium butyrate (SB), samples of the murine tissue, PMNs in peripheral blood, and BALF of the rats were collected at different time-points. The expression level of HMGB1 mRNA in murine lung tissue was examined by RT-PCR. Apoptotic changes of PMN were determined by flow cytometric (FCM) analysis, Giemsa staining, and TdT-mediated dUTP nick end labeling (TUNEL) method. Results The percentage of apoptosis of PMN in rat model of LPS-induced ALI was gradually decreased as compared with that of normal control. The apoptosis-initiation time and non-survival time of PMN in rat BALF were prolonged significantly as compared with that of normal control. The HMGB1 mRNA expression in impaired murine lung tissue was upregulated 6-24 h after LPS exposure, but SB intervention could significantly suppress the upregulation. The morphologic examination indicated that the edema severity and pathological changes of lung tissues were excessively aggravated in rats after LPS administration. SB treatment diminished the severity of lung damage. Combined with lung HMGB1 expression level, the above changes indicated that the pathological changes of lung tissue were related to the HMGB1 expression in impaired lung, as well as apoptotic changes in PMN. Conclusion After LPS challenge, high expression of rat lung HMGB1 mRNA occurs at a later phase, but keeps for a long time. SB treatment can attenuate the delay of LPS-induced PMN apoptosis and down-regulate HMGB1 mRNA expression of impaired lung. The results demonstrate that HMGB1 may contribute to the development of PMN apoptotic changes during LPS-induced acute lung injury.