休克期切痂对烫伤大鼠肝、肺组织高迁移率族蛋白B1表达及促炎/抗炎平衡的影响

Effects of escharectomy during shock stage on tissue high mobility group box-1 expression and balance of pro-/anti-inflammatory response in rats after severe thermal injury

目的 观察休克期切痂对烫伤大鼠组织早期和晚期炎症介质变化规律及相应器官功能的影响 ,探讨休克期切痂改善预后的分子机制。方法 Wistar大鼠 30 %Ⅲ度烫伤后随机分为 2 4h切痂组和 72h切痂组。分别检测肝、肺组织高迁移率族蛋白B1(HMGB1)、白介素 10 (IL 10 )及肿瘤坏死因子 α(TNF α)的表达。结果 烫伤后 2d ,肝、肺组织HMGB1、TNF αmRNA表达增强 ,而IL 10mRNA伤后 8d增强 ;2 4h切痂大鼠伤后 4d肝、肺组织HMGB1和TNF αmRNA表达下调 ,伤后 8d其IL 10mRNA表达恢复正常 ;72h切痂大鼠伤后 8d肝、肺IL 10mRNA仍维持较高水平。伤后 2、8d肝组织内TNF α蛋白水平呈双峰改变 ,4d时减少 ;2 4h和 72h切痂组肝TNF α维持在正常范围 ;伤后 2、4d肝TNF α/IL 10比例升高 ,2 4h切痂可降低TNF α/IL 10。此外 ,2 4h切痂组 4、8d血浆天冬氨酸氨基转移酶和丙氨酸氨基转移酶含量及肺组织髓过氧化物酶活性显著降低。结论 休克期切痂可阻断严重烫伤大鼠肝、肺组织早期和晚期炎症介质过度表达 ,维持促炎 /抗炎介质平衡 。

Objective To investigate the effects of escharectomy during shock stage on tissue high mobility group box 1 protein (HMGB1) expression and balance of pro /anti inflammatory cytokines, and to elucidate the potential mechanism underlying beneficial effect of early escharectomy after severe burns Methods Wistar rats inflicted by 30% full thickness thermal injury were randomly divided into thermal injury group, 24 h escharectomy group and 72 h escharectomy group, in which escharectomy were performed at 24 and 72 h postburn, respectively Gene expression of HMGB1, interleukin 10 (IL 10), and tumor necrosis factor α (TNF α) in liver and lungs was detected with reverse transcription PCR, and protein levels of IL 10 and TNF α in liver and lung tissues were measured by ELISA The plasma AST and ALT contents, and pulmonary myeloperoxidase (MPO) activity were also assayed Results The mRNA expression of HMGB1 and TNF α in liver and lungs was up regulated on postburn day 2, with IL 10 over expression on postburn day 8 In the 24 h escharectomy group, HMGB1 and TNF α mRNA expression in liver and lungs was down regulated on postburn day 4, and IL 10 expression returned to normal range on postburn day 8, while the down regulation of HMGB1, TNF α and IL 10 were not noted in the 72 h escharectomy group There were two peaks in liver TNF α protein levels appearing on postburn days 2 and 8, respectively, with an unexpected marked decrease on day 4 in thermal injury controls, yet liver TNF α levels maintained in normal range in animals of 24 h and 72 h escharectomy groups The ratios of TNF α to IL 10 protein levels in liver tissue were significantly increased on postburn days 2 and 4 ( P =0 0001 and 0 002, respectively), while escharectomy during shock stage markedly reduced hepatic TNF α to IL 10 ratios ( P =0 0008 and 0 040, respectively) No significant changes in TNF α protein levels in lung tissue were observed Additionally, plasma AST as well as ALT contents, and pulmonary MPO activity were markedly decreased on postburn days 4 and 8 in the 24 h escharectomy group compared to the 72 h escharectomy group or thermal injury controls ( P <0 05) Conclusions Escharectomy during burn shock stage could inhibit the over expression of both early and late inflammatory mediators, and maintain the balance of pro /anti inflammatory response, thereby improving multiple organ functions in rats following severe burns