Repertaxin, a novel inhibitor of rat CXCR2 function, inhibits inflammatory responses that follow intestinal ischaemia and reperfusion injury

Abstract

1 Neutrophils are thought to play a major role in the mediation of reperfusion injury. CXC chemokines are known inducers of neutrophil recruitment. Here, we assessed the effects of Repertaxin, a novel low molecular weight inhibitor of human CXCL8 receptor activation, on the local, remote and systemic injuries following intestinal ischaemia and reperfusion (I/R) in the rat. 2 Pre-incubation of rat neutrophils with Repertaxin (10 -11-10 -6 M) inhibited the chemotaxis of neutrophils induced by human CXCL8 or rat CINC-1, but not that induced by fMLP, PAF or LTB 4, in a concentration-dependent manner. Repertaxin also prevented CXCL8-induced calcium influx but not CXCL8 binding to purified rat neutrophils. 3 In a model of mild I/R injury (30 min of ischaemia and 30 min of reperfusion), Repertaxin dose-dependently (3-30 mg kg -1) inhibited the increase in vascular permeability and neutrophil influx. Maximal inhibition occurred at 30 mg kg -1. 4 Following severe I/R injury (120 min of ischaemia and 120 min of reperfusion), Repertaxin (30 mg kg -1) markedly prevented neutrophil influx, the increase in vascular permeability both in the intestine and the lungs. Moreover, there was prevention of haemorrhage in the intestine of reperfused animals. 5 Repertaxin effectively suppressed the increase in tissue (intestine and lungs) and serum concentrations of TNF-α and the reperfusion-associated lethality. 6 For comparison, we also evaluated the effects of an anti-CINC-1 antibody in the model of severe I/R injury. Overall, the antibody effectively prevented tissue injury, systemic inflammation and lethality. However, the effects of the antibody were in general of lower magnitude than those of Repertaxin. 7 In conclusion, CINC-1 and possibly other CXC chemokines, acting on CXCR2, have an important role during I/R injury. Thus, drugs, such as Repertaxin, developed to block the function of the CXCR2 receptor may be effective at preventing reperfusion injury in relevant clinical situations.