Abstract
Purpose: :
We have shown earlier that aldose reductase (AR) mediates oxidative stress–induced nuclear factor (NF)–kappaB activation. Since LPS is known to cause cytotoxicity via oxidative stress, we have investigated the in vitro anti–inflammatory effects of AR inhibition on LPS–induced activation of NF–ΚB–dependent signals in human lens epithelial cells.
Methods: :
Growth– arrested HLEC were cultured without or with AR inhibitors or transfected with an AR antisense mRNA. Subsequently, the cells were stimulated with LPS (1 µg/ml) for 24 h. The cell viability was assessed by cell counts and MTT assay and the apoptosis was measured by nucleosomal degradation. Electrophoretic mobility gel shift assays were carried out to determine the activation of NF–ΚB and AP1. The levels of nitric oxide, MMP2, MMP9, Cox–2 and TNF–α were measured by using specific ELISA kits. Western blot analysis was carried out to determine the cleavage of PARP, and activation of PKC and MAPK.
Results: :
Bacterial LPS caused apoptosis of HLEC. Inhibition of AR by two structurally unrelated inhibitors – sorbinil and tolrestat, or ablation by AR antisense prevented the LPS–induced apoptosis. AR inhibition/ablation also prevented the LPS–induced activation of caspase–3, PKC, NF–ΚB, AP1, MAPK and the expression of Cox–2, MMP2, MMP9 and TNF–α proteins in HLEC.
Conclusions: :
The results indicate that the activation of redox sensitive transcription factor, NF–kB signals are predominant during bacterial infection–induced disease progression and inhibition of AR is a potential therapeutic target for visual complications.
Keywords: cytokines/chemokines • cell survival • inflammation