Abstract
Purpose: :
To evaluate and compare TLR–3 signaling and IFN–beta production in human retinal endothelial (HREC) and retinal pigment epithelial (HRPE) cells.
Methods: :
HREC and HRPE cells were propagated in vitro. The cultured cells were incubated with media, a cytokine mix (TNF–alpha, IFN–gamma and IL–1 beta), poly I:C (an analog of dsRNA), LPS or IFN–beta. Supernatant fluids were harvested at varying times after stimulation. EIA was used to determine the presence of IFN–beta or sE–selectin proteins. Gene expression was determined by RT–PCR
Results: :
Both HREC and HRPE cells produced IFN–beta in response to poly I:C. However the kinetics of this production were different, with a maximum of 9 IU/ml at 4hr in HRECS and continued increases in HRPE to 180 IU/ml at 48hr post stimulation. IFN–beta production in both cell types was blocked by antibody to TLR–3. Treatment with poly I:C resulted in increased gene expression of not only TLR–3 and IFN–beta but also MxA, an antiviral protein produced in response to IFN–beta. Pretreatment of HRECS with IFN–beta resulted in a >50% reduction in cytokine–induced sE–selectin release.
Conclusions: :
Poly I:C increased IFN–beta production in HRECs and HRPEs through a mechanism involving TLR–3. Moreover these studies demonstrate that IFN–beta produced within the retina has antiviral and immunosuppressive actions.
Keywords: retina • vascular cells • retinal pigment epithelium