Retinal Photoreceptor Expresses Toll-Like Receptors (TLRs) and Elicits Innate Responses Following TLR Ligand and Bacterial Challenge

Toll-like receptors (TLRs) play an important role in host defense against microbial pathogens. Our previous studies have shown that TLRs are expressed on various retinal cells (Microglia and Müller glia) and orchestrate retinal innate responses in bacterial endophthalmitis. In this study, we used a...

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Main Authors:	Singh, Pawan Kumar, Kumar, Ashok
Format:	Online
Language:	English
Published:	Public Library of Science 2015
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4358976/

id	pubmed-4358976
recordtype	oai_dc
spelling	pubmed-43589762015-03-23 Retinal Photoreceptor Expresses Toll-Like Receptors (TLRs) and Elicits Innate Responses Following TLR Ligand and Bacterial Challenge Singh, Pawan Kumar Kumar, Ashok Research Article Toll-like receptors (TLRs) play an important role in host defense against microbial pathogens. Our previous studies have shown that TLRs are expressed on various retinal cells (Microglia and Müller glia) and orchestrate retinal innate responses in bacterial endophthalmitis. In this study, we used a well-characterized mouse cone photoreceptor cell line (661W); and demonstrated that these cells express all known TLRs. Although the stimulation of 661W cells with TLR ligands (Pam3Cys, PolyI:C, LPS, Flagellin, Poly DT, and ODN) did not alter TLR expression, downstream TLR-signaling pathways (NF-κB, p38, and ERK) are activated. Moreover, TLR-activated 661W cells secreted significant amounts of inflammatory mediators (IL-6, IL-1β, MIP-2, and KC) in their culture supernatant, as assessed by ELISA. A similar trend was observed in 661W cells challenged with live bacteria (Staphylococcus aureus). Interestingly, the neutralization of TLR2, a major receptor for S. aureus recognition, did not significantly attenuate bacterial-induced inflammatory mediators, suggesting the existence of TLR2-independent mechanisms in photoreceptor cells. Together, these results indicate that photoreceptors constitutively express functional TLRs and possess the ability to initiate innate responses following pathogen challenge, implicating their role in retinal innate immunity. Public Library of Science 2015-03-13 /pmc/articles/PMC4358976/ /pubmed/25767877 http://dx.doi.org/10.1371/journal.pone.0119541 Text en © 2015 Singh, Kumar http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Singh, Pawan Kumar Kumar, Ashok
spellingShingle	Singh, Pawan Kumar Kumar, Ashok Retinal Photoreceptor Expresses Toll-Like Receptors (TLRs) and Elicits Innate Responses Following TLR Ligand and Bacterial Challenge
author_facet	Singh, Pawan Kumar Kumar, Ashok
author_sort	Singh, Pawan Kumar
title	Retinal Photoreceptor Expresses Toll-Like Receptors (TLRs) and Elicits Innate Responses Following TLR Ligand and Bacterial Challenge
title_short	Retinal Photoreceptor Expresses Toll-Like Receptors (TLRs) and Elicits Innate Responses Following TLR Ligand and Bacterial Challenge
title_full	Retinal Photoreceptor Expresses Toll-Like Receptors (TLRs) and Elicits Innate Responses Following TLR Ligand and Bacterial Challenge
title_fullStr	Retinal Photoreceptor Expresses Toll-Like Receptors (TLRs) and Elicits Innate Responses Following TLR Ligand and Bacterial Challenge
title_full_unstemmed	Retinal Photoreceptor Expresses Toll-Like Receptors (TLRs) and Elicits Innate Responses Following TLR Ligand and Bacterial Challenge
title_sort	retinal photoreceptor expresses toll-like receptors (tlrs) and elicits innate responses following tlr ligand and bacterial challenge
description	Toll-like receptors (TLRs) play an important role in host defense against microbial pathogens. Our previous studies have shown that TLRs are expressed on various retinal cells (Microglia and Müller glia) and orchestrate retinal innate responses in bacterial endophthalmitis. In this study, we used a well-characterized mouse cone photoreceptor cell line (661W); and demonstrated that these cells express all known TLRs. Although the stimulation of 661W cells with TLR ligands (Pam3Cys, PolyI:C, LPS, Flagellin, Poly DT, and ODN) did not alter TLR expression, downstream TLR-signaling pathways (NF-κB, p38, and ERK) are activated. Moreover, TLR-activated 661W cells secreted significant amounts of inflammatory mediators (IL-6, IL-1β, MIP-2, and KC) in their culture supernatant, as assessed by ELISA. A similar trend was observed in 661W cells challenged with live bacteria (Staphylococcus aureus). Interestingly, the neutralization of TLR2, a major receptor for S. aureus recognition, did not significantly attenuate bacterial-induced inflammatory mediators, suggesting the existence of TLR2-independent mechanisms in photoreceptor cells. Together, these results indicate that photoreceptors constitutively express functional TLRs and possess the ability to initiate innate responses following pathogen challenge, implicating their role in retinal innate immunity.
publisher	Public Library of Science
publishDate	2015
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4358976/
_version_	1613198365465509888

Retinal Photoreceptor Expresses Toll-Like Receptors (TLRs) and Elicits Innate Responses Following TLR Ligand and Bacterial Challenge

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