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Toll-like Receptor 2 Facilitates Oxidative Damage-Induced Retinal Degeneration
Journal article   Open access   Peer reviewed

Toll-like Receptor 2 Facilitates Oxidative Damage-Induced Retinal Degeneration

Kelly Mulfaul, Ema Ozaki, Nilisha Fernando, Kiva Brennan, Kathleen R Chirco, Emma Connolly, Chris Greene, Arvydas Maminishkis, Robert G Salomon, Mikhail Linetsky, …
Cell reports (Cambridge), Vol.30(7), pp.2209-2224.e5
02/18/2020
DOI: 10.1016/j.celrep.2020.01.064
PMCID: PMC7179253
PMID: 32075760
url
https://doi.org/10.1016/j.celrep.2020.01.064View
Published (Version of record) Open Access

Abstract

Retinal degeneration is a form of neurodegenerative disease and is the leading cause of vision loss globally. The Toll-like receptors (TLRs) are primary components of the innate immune system involved in signal transduction. Here we show that TLR2 induces complement factors C3 and CFB, the common and rate-limiting factors of the alternative pathway in both retinal pigment epithelial (RPE) cells and mononuclear phagocytes. Neutralization of TLR2 reduces opsonizing fragments of C3 in the outer retina and protects photoreceptor neurons from oxidative stress-induced degeneration. TLR2 deficiency also preserves tight junction expression and promotes RPE resistance to fragmentation. Finally, oxidative stress-induced formation of the terminal complement membrane attack complex and Iba1+ cell infiltration are strikingly inhibited in the TLR2-deficient retina. Our data directly implicate TLR2 as a mediator of retinal degeneration in response to oxidative stress and present TLR2 as a bridge between oxidative damage and complement-mediated retinal pathology. [Display omitted] •TLR2 activates the alternative complement pathway•TLR2 signaling triggers sub-lytic MAC formation on retinal pigment epithelial cells•TLR2 deficiency reduces oxidative stress-induced C3 and MAC in the outer retina•TLR2 blockade protects photoreceptors and RPE from oxidative stress-induced cell death Oxidative stress and complement deposition are common to many retinal degenerative diseases. Mulfaul et al. demonstrate that TLR2 blockade protects against photoreceptor neuronal cell death and RPE fragmentation in experimental models of oxidative stress-induced retinal degeneration and present TLR2 as a bridge between oxidative damage and complement-mediated retinal pathology.
2-(ω-Carboxyethyl) pyrrole age-related macular degeneration (AMD) C5b-C9 Complement Membrane Attack Complex (MAC) NaIO3 oxidative stress retinal degeneration Toll-like receptor 2 (TLR2)

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