Abstract
Abstract: :
Purpose: We have previously showed that IL-6 is upregulated in rat retinas after retinal ischemia-reperfusion. The aim of this study was to investigate whether IL-6 production after retinal ischemia-reperfusion is linked to NF-ΚB activation and the expression of its endogenous inhibitor, IΚB-α. Methods: Cannulas connected to a saline column to generate a pressure of 110mmHg were inserted into the anterior chambers of eye of adult Lewis albino rats and kept there for 1 hour. Retinal ischemia was confirmed by observing the whitening of the anterior segment and blanching of the retina. Reperfusion was established after ischemia. Animals were euthanized at 2, 4, 8, 12, 18, 24, 48 hours. Immuno-colocalization and semiquantitative real-time RT-PCR were performed to study the distribution and the expression of NF-ΚB, IΚB-α and IL-6. Results: Immunohistochemistry of phospho-IΚB-α showed increased labeling in scattered microglia/macrophage-like cells in the inner retina with an apparent maximum at 12 hours. Double-labeling of phospho-IΚB-α with IL-6 showed co-localization of IΚB-α and IL-6 in microglia/macrophage-like cells, which were also marked by ED1 antibody in the inner retina. Semiquantitative real-time RT-PCR showed an elevated NF-ΚB mRNA (n=3) levels at 2 hours and 12 hours, coinciding with elevated IL-6 mRNA (n=3) levels at similar times. IΚB-α mRNA (n=3) also showed elevated levels at 8 hours, compared with that of normal (n=3). Conclusions: After retinal ischemia-reperfusion injury, the expression of IL-6 by microglia/macrophage-like cells may be regulated by NF-ΚB activation and phosphorylation of IΚB-α.
Keywords: ischemia • cytokines/chemokines • signal transduction