INTERLEUKIN-1 GENE-EXPRESSION IN TRANSIENT RETINAL ISCHEMIA IN THE RAT

Purpose. To determine in rats whether there are time-dependent changes in interleukin-1 alpha (IL-1 alpha) and interleukin-1 beta (IL-1 beta ) gene expression in transient retinal ischemia and to localize their mRNAs in the retina. Methods. Retinal ischemia was induced in Sprague- Dawley rats by ligating the optic nerve. Two hours later, the ligature was released and reperfusion occurred. The levels of IL-1 alpha and I L-1 beta gene expression in the sensory retina were then compared at v arious times after reperfusion by a semiquantitative polymerase chain reaction method. Localization of their expressed mRNAs was examined by in situ hybridization histochemistry. Results. Little expression of I L-1 alpha and IL-1 beta genes was observed in normal retina. IL-1 alph a gene expression rapidly increased (about 30-fold greater than that o f the control) as early as 1 hour after cessation of ischemia, reached a peak (about 50-fold) at 3 to 12 hours, and then gradually decreased to near baseline levels. IL-1 beta gene expression began to increase 2 hours later than did that of IL-1 alpha and had two peaks. IL-1 beta gene was found by in situ hybridization histochemistry to be expresse d by retinal glial cells, endothelial cells, and neutrophils infiltrat ing the retina and vitreous. No gene expression was found in the contr ol retinas. Conclusions. Expression of IL-1 alpha and IL-1 beta genes was dramatically upregulated during reperfusion after induced retinal ischemia. IL-1 beta gene was expressed by retinal glial cells, endothe lial cells, and neutrophils recruited into the retina. From these resu lts, it appeared that IL-1 may have an important role in retinal ische mia-reperfusion injury.