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Mohammed Qutub, Natàlia Vilà, Shawn C Maloney, Dana Faingold, Nouf AlSaati, Emilia Antecka, Miguel N Burnier; Toll-like receptor 3 is expressed in all layers of the human retina. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2871.
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© ARVO (1962-2015); The Authors (2016-present)
Recent studies have found that dysregulation of Toll-like receptor 3 (TLR3)—a key player in innate immunity—in retinal pigmented epithelium (RPE) may play a role in retinal oxidative stress. The aim of this study was to evaluate the expression of TLR3 in all layers of the normal human retina.
Nineteen formalin-fixed, paraffin-embedded sections of normal human donor eyes were used in this study. Mean age of donors was 62.8±31.5 years (12 female, 7 male). Immunohistochemistry was performed using antibody against human TLR3 and staining was scored according to intensity (0=negative, 1=low-to-moderate, 2=strong) and extent (0=negative, 1=staining ≤50% of cells, 2=staining >50% of cells) of staining. A combined immunoreactive score (IRS) was calculated to describe the expression of TLR3 using the following equation: 2 x extent x intensity. Results were expressed in the following manner: 0 to 2=negative, >2 to 4= weak expression, >4 = strong expression. We compared the IRS between the layers of the macula and peripheral retina. We additionally analyzed the correlation between IRS and age. Statistical analysis was performed using analysis of variance (ANOVA) and Pearson’s correlation.
TLR3 was heterogeneously expressed in all layers of the retina. The following layers were graded as having a high IRS: ganglion cell, outer plexiform, photoreceptors and RPE. Weak staining was observed in the remaining retinal layers. No significant differences were seen between macular and peripheral retina for TLR3 staining in any retinal layer. However, 4/19 cases (mean age 76.5 years) had stronger staining in peripheral RPE than macular RPE, while one case (age = 10 months) had stronger staining in macular RPE than peripheral RPE. Furthermore, there was no statistically significant correlation between age and intensity of staining in retinal structures.
TLR3 is expressed in all retinal layers. Therefore, these results provide an overview of TLR3 expression throughout the human retina. This information may serve as a foundation for further research that evaluates TLR3 expression in an array of ophthalmic conditions, including those in which oxidative stress is a factor.
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