OBJECTIVETo 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.

METHODSWistar 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-alpha (TNF-alpha) in liver and lungs was detected with reverse-transcription PCR, and protein levels of IL-10 and TNF-alpha in liver and lung tissues were measured by ELISA. The plasma AST and ALT contents, and pulmonary myeloperoxidase (MPO) activity were also assayed.

RESULTSThe mRNA expression of HMGB1 and TNF-alpha 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-alpha 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-alpha and IL-10 were not noted in the 72 h escharectomy group. There were two peaks in liver TNF-alpha 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-alpha levels maintained in normal range in animals of 24 h and 72 h escharectomy groups. The ratios of TNF-alpha 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-alpha to IL-10 ratios (P = 0.0008 and 0.040, respectively). No significant changes in TNF-alpha 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).

CONCLUSIONSEscharectomy 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.