Transient Increase of Cytokine-Induced Neutrophil Chemoattractant, a Member of the Interleukin-8 Family, in Ischemic Brain Areas After Focal Ischemia in Rats

Abstract

Background and Purpose We have indicated that neutrophils play an important role in cerebral ischemia-reperfusion injury. Neutrophils are also known to adhere to the endothelial wall through adhesion molecules and to infiltrate into the tissue, and this neutrophilic invasion correlates with the concentration gradient of chemotactic factors. The aim of the present study was to evaluate the role of cytokine-induced neutrophil chemoattractant (CINC) on brain damage in rats from transient ischemia. Methods The brain water content was measured to evaluate postischemic brain injury in rats with 60 minutes of middle cerebral artery occlusion with reperfusion. An enzyme-linked immunosorbent assay was used to evaluate the blood and brain concentrations of CINC, and enzymatic and histological techniques were used to measure the neutrophilic infiltration into the brain. Results The increase of water content was first observed at 6 hours after reperfusion, after which this increase was gradual, with brain edema peaking from 24 to 48 hours after reperfusion. Neutrophilic infiltration into the parenchyma and myeloperoxidase activity were first noted 12 hours after reperfusion, after which a marked increase occurred from 24 to 48 hours after reperfusion. In the ischemic brain areas, CINC was first detected at 3 hours after reperfusion. The CINC level peaked at 12 hours after reperfusion (9.15±0.45 ng/g wet wt, n=5) and then gradually reduced from 24 to 48 hours after reperfusion (5.35±0.95 ng/g wet wt, n=5, and 1.25±0.10 ng/g wet wt, n=5, respectively). Interestingly, the serum CINC concentration was transiently elevated from 3 to 6 hours after reperfusion. No CINC production was detected in the brain of rats subjected to 60 minutes of ischemia without reperfusion. Conclusions A marked increase in CINC concentration was detected in brain and serum during early reperfusion. This suggests that the time course of CINC production precedes brain edema formation and neutrophilic infiltration. It thus appears that CINC may play an important role in neutrophilic infiltration in ischemic lesion and in brain edema formation after ischemia-reperfusion injury.