Inflammatory and redox responses to ischaemia/reperfusion in human skeletal muscle

The objective of this study was to identify cellular and plasma marker(s) of post-I/R (ischaemia/reperfusion) in patients undergoing elective knee surgery where a tourniquet was used to facilitate a bloodless surgical field. We evaluated the inflammatory and redox response by measuring the mRNA levels of ICAM-1 (intercellular cell-adhesion molecule-1), MnSOD (manganese superoxide dismutase), GST-μ (glutathione transferase-μ) and Cu/ZnSOD (copper/zinc superoxide dismutase) in the operated muscle and blood cells pre-operatively (pre-tourniquet) and at various times after reperfusion (tourniquet release). We also measured plasma concentrations of IL (interleukin)-6, IL-8, sICAM-1 (soluble ICAM-1), IL-1β and TNF-α (tumour necrosis factor-α) using ELISA. Our results show a strong induction of MnSOD and GST-μ in granulocytes (but not in mononuclear cells or muscle) after reperfusion (2 and 4 h). There was no change in the mRNA level of Cu/ZnSOD after reperfusion. An up-regulation of membrane ICAM-1 in muscle and a decrease in sICAM-1 in plasma were detected after reperfusion. Plasma IL-6 and IL-8 levels (but not TNF-α or IL-1β) increased significantly over baseline at 2 and 4 h after reperfusion. Elevated expression of ICAM-1 in muscle, MnSOD and GST-μ in granulocytes and increased levels of plasma IL-6 and IL-8 may be considered as phase- and cell-specific markers of post-I/R of skeletal muscle in humans.