Abstract
Purpose:
Inflammatory responses of retinal pigment epithelium (RPE) are implicated in the pathogenesis of age-related macular degeneration (AMD). RPE cells in culture respond to the proinflammatory cytokines IFN-γ, TNF-α and IL-1β by increasing the expression of chemokines and cytokines. Resveratrol, a naturally occurring polyphenol, is a well characterized anti-inflammatory antioxidant. The purpose of the present study is to investigate whether resveratrol can modulate the effect of IFN-γ, TNF-α and IL-1β on RPE cells.
Methods:
Confluent cultures of ARPE-19 cells were treated with a proinflammatory cytokine mixture containing IFN-γ, TNF-α and IL-1β in a serum free medium for various time intervals. Total RNA fraction was then isolated and real-time PCR analysis of gene expression was performed using TaqMan reagents (Applied Biosystems) with GAPDH as an endogenous control. The activation of nuclear factor-κB (NFκB) was examined by western immunoblot analysis of cell extracts using anti-phospho-NFκB p65 (Ser536) antibody.
Results:
Pretreatment of ARPE-19 cells with resveratrol (50 µM) effectively blocked the induction of CCL5, CXCL9, CSF2 and NOS2A (inducible form of nitric oxide synthase) by the proinflammatory cytokines (IFN-γ + TNF-α + IL-1β). Resveratrol also prevented the decrease in the expression of HMOX1 (heme oxygenase-1) in cells exposed to proinflammatory cytokines. Immunoblot analysis showed that the phospo-NFκB p65 increased in cells in response to the treatment with proinflammatory cytokines. This increase in phosphorylation was considerably reduced in the presence of resveratrol.
Conclusions:
Resveratrol attenuated the inflammatory response of the RPE cells in culture by its ability to block the activation of NFκB signaling pathway by the proinflammatory cytokines. Thus, resveratrol, due to its ability to protect RPE from inflammatory insults, may have therapeutic potential as a nutraceutical in arresting the development of ocular degenerative diseases such as AMD.
Keywords: 557 inflammation •
701 retinal pigment epithelium •
424 antioxidants