Proinflammatory cytokines gene expression in skin flaps with arterial and venous ischemia in rats

Infiltration of inflammatory cells is the crucial element in ischemia-reperfusion injury of the microsurgical flap. Cytokines are a large functional group of polypeptide regulatory molecules that influence the activity of various cell types through autocrine and paracrine mechanisms. In this study, expression of selected proinflammatory cytokines was examined in skin flaps with arterial and venous ischemia in the rat model. Fifty-four Sprague-Dawley rats were used in the study. The ischemia of each flap was induced by clamping its vascular pedicle for 6 hr. The flap was then replaced and allowed to reperfuse. All flaps were biopsied immediately post-event, and at 3, 6 and 18 hr after reperfusion. Expression of tumor necrosis factor (TNF-alpha), interleukin (IL-1beta), and monocyte chemoattractant protein-1 (MCP-1) mRNA was determined by RT-PCR in each case. The same number of skin flaps without ischemia was used for baseline gene expression. Results showed that the TNF-alpha expression was significantly up-regulated in the flaps with arterial ischemia at 6 hr after reperfusion. In the flaps with venous ischemia, MCP-1 expression was increased with its peak expression at 3 hr after reperfusion. IL-1beta expression was increased threefold in the flaps subjected to venous ischemia and following reperfusion in 3 hr, but the peak expression in the flap with arterial ischemia was observed at 18 hr after reperfusion. This study delineated the changes in expression of these proinflammatory cytokines in flaps with arterial and venous ischemia reperfusion injury, and showed that cytokine expression was different in the arterial and venous injuries.