Abstract
Purpose: :
To investigate the effect of aldose reductase (AR) inhibition on cytotoxic signals induced by bacterial endotoxin lipopolysaccharide (LPS) in human non-pigmented ciliary epithelial cells (NPE) cells.
Methods: :
The NPE cells were stimulated with LPS, cell viability was assessed by cell counting and MTT assay. The levels of nitric oxide, PGE2 were measured by ELISA kits. The activation of NF-ΚB and AP1 was determined by Gel-shift assay. The activation of MAPKs and expression of Na/K-ATPase and inflammatory marker proteins iNOS, COX-2, and ICAM-1 were determined by Western blot. Lewis rats were injected subcutaneously with LPS without or with AR inhibitor zopolrestat. The rats were euthanized 24 h after LPS injection and the eyes were enucleated and fixed. Sagittal sections of rat eyes representing ciliary body region were used for immunohistochemical studies.
Results: :
LPS-induced apoptotic cell death was significantly prevented by the AR inhibitor or AR-siRNA. LPS -induced increase in the phosphorylation of MAPKs (ERK1/2) and SAPK/JNK, and activation of NF-ΚB and AP-1 in NPE cells were prevented by inhibition of AR. Further, AR inhibition also prevents LPS-induced secretion of inflammatory markers PGE2 and NO in the culture medium as well as increased expression of COX-2 and iNOS proteins in NPE cells as well as in rat eye ciliary bodies.
Conclusions: :
Our results suggest that AR regulates LPS-induced cytotoxic stress signals in NPE cells and that inhibition of AR could be a novel therapeutic approach for ocular complications.
Keywords: inflammation • signal transduction • oxidation/oxidative or free radical damage