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 / 中华外科杂志

ABSTRACT

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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-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.</p><p><b>RESULTS</b>The 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).</p><p><b>CONCLUSIONS</b>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.</p>