Purchase this article with an account.
P.K. Mukherjee, N.G. Bazan; Toll–Like Receptor Expression in Oxidative Stress–Induced Human Retinal Pigment Epithelial ARPE–19 Cells: Inhibitory Response in Apoptosis . Invest. Ophthalmol. Vis. Sci. 2005;46(13):177.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: The Toll–like receptor (TLR) family in mammals consists of a family of transmembrane proteins characterized by multiple copies of leucine–rich repeats in the extracellular domain and an IL–1ß receptor motif in the cytoplasmic domain. Toll–like receptors (TLRs) activate the inmate immune system and constitute an important and unrecognized component of human immune system. Here, we studied the time–dependent expression of Toll receptors TLR–1, 2, 4, and 5 under oxidative stress and during ROS (rod outer segment) phagocytosis in RPE. We also studied the involvement of Toll expression in apoptosis induced by oxidative stress. Methods: ARPE–19 cells (80% confluent) were serum–starved for 8 hours. Oxidative stress was induced by TNFα/H2O2 and samples were collected at 2, 4, 6, 8, 10 and 15 hours after oxidative stress, homogenized, and used for Western–blot analysis using TLR–specific antibodies. Apoptotic cell death induced by oxidative stress was scored by Hoechst staining. Results: Toll receptors TLR2 and TLR5, but not TLR1 and TLR4, were expressed under oxidative stress in RPE. This expression reached a peak at 6–8 hours after oxidative stress for TLR2 and reached a plateau at later hours. On the other hand, TLR5 continued to rise until it reached a plateau at 15 hours. This expression of TLR2 was further up–regulated by ROS and TLR ligands PGN and LTA. The apoptotic cell death induced by oxidative stress was substantially inhibited by ROS treatment and TLR ligands PGN and LTA. Conclusions: The expression of TLR2 and TLR5, but not the other two Toll receptors, under oxidative stress in RPE indicates that these two Toll receptors may play an important role in cell signaling. The enhanced expression of TLR2 by ROS phagocytosis and inhibition of apoptosis by ROS phagocytosis implies that TLR2 receptor may trigger cell–survival signaling. Supported by NIH EY05121
This PDF is available to Subscribers Only