Purchase this article with an account.
Sindhu Saraswathy, Angeline M. Nguyen, Narsing A. Rao; The Role of TLR4 in Photoreceptor αA Crystallin Upregulation during Early Experimental Autoimmune Uveitis. Invest. Ophthalmol. Vis. Sci. 2010;51(7):3680-3686. doi: 10.1167/iovs.09-4575.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Previous studies indicate that the upregulation of αA crystallin prevents photoreceptor mitochondrial oxidative stress–mediated apoptosis in experimental autoimmune uveitis (EAU). In this study, the role of TLR4 was investigated in the upregulation of αA crystallin in the retinas of animals with EAU.
TLR4−/−, iNOS−/−, TNF-α−/−, MyD88−/−, wild-type (WT) control (C57BL/6), and nude mice (B6.Cg-Foxn1nu) were immunized with IRBP mixed with complete Freund's adjuvant; eyes were enucleated on day 7 after immunization. Real-time polymerase chain reaction was first used to detect upregulated inflammatory cytokines and αA crystallin in retinas with EAU; confirmed with Western blot analysis, and the site of upregulation was localized by immunohistochemistry. Oxidative stress was localized using 8-OHdG, and TUNEL staining was used to detect apoptosis.
In early EAU, increased expression of TNF-α, iNOS, and αA crystallin genes were detected in the retinas of WT mice, whereas such upregulation was absent in TLR4-deficient mice (P < 0.001). αA Crystallin was not elevated in MyD88−/−, TNF-α−/−, and iNOS−/− mice with EAU. Immunostaining revealed TNF-α, iNOS, and αA crystallin localization in the photoreceptor inner segments and outer plexiform layer in the WT controls with EAU; but such staining was absent in TLR4-deficient mice with EAU. 8-OHdG staining showed oxidative stress in the photoreceptors in WT mice with EAU and there was no apoptosis.
TLR4 plays an important role in the upregulation of αA crystallin through the interaction of MyD88 and the subsequent generation of TNF-α and iNOS in the EAU retina. Such crystallin upregulation may prevent oxidative stress–mediated apoptosis of photoreceptors in uveitis.
This PDF is available to Subscribers Only