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Carlos Quezada, Patrick Logan, Ana Beatriz Toledo Dias, Francisco Ceballos, Lisa Jagan, Tiago Briccoli, Miguel N Burnier, The Henry C Witelson Ocular Pathology Laboratory; Elevated photoreceptor COX-2 expression correlates with aging retinas. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1852.
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While COX-2 is often associated with inflammation and neoplasia, published reports have shown COX-2 to be expressed in normal tissue. Our aim was to evaluate expression of COX-2 in all layers of the normal human retina and determine whether correlations with age or gender exist
130 formalin-fixed, paraffin-embedded normal human eyes were selected to investigate the expression of COX-2. Immunohistochemistry was performed using anti-human COX-2 antibody. Immunostaining was classified based on intensity (negative=0, weak=1, strong=2) and extent (negative=0, staining ≤50% of cells=1, staining >50% of cells=2). An immunoreactive score (IRS) was calculated to describe the expression of COX-2 using the following equation: 2 x expression x intensity. Results were expressed in the following manner: 0-2=negative, 3-4=weak, ≥5=strong. Logistic regression analysis was conducted to estimate the association between age and staining score of any layer. Linear regression analysis was used to determine possible correlations between IRS and time elapsed between death and enucleation or enucleation and tissue processing p-value <0.05 was considered statistically significant
Of the 130 eyes evaluated, 72 were from female donors, 53 from male donors, and 5 from donors with no gender information. Mean age was 62.1 years. A total of 78 cases had RPE and 66 had sufficient neurosensory retina for evaluation. The number of cases with positive COX-2 expression by retinal layer was: retinal pigmented epithelium (RPE): 61/78; nerve fiber layer: 33/66; ganglion cell layer: 58/66; inner plexiform layer: 55/66; inner nuclear layer: 36/66; outer plexiform layer: 56/66; outer nuclear layer: 31/66; photoreceptors: 55/66. COX-2 expression in the photoreceptors was significantly correlated with older donor age (p=0.045). COX-2 IRS was strong in the ganglion cell, photoreceptor and RPE layers. No significant correlations were found between IRS and time elapsed between death and enucleation or IRS and time elapsed between enucleation and tissue processing
COX-2 is expressed throughout the normal human retina with strong expression on ganglion cell, photoreceptor and RPE layers. Its expression in photoreceptors is significantly correlated with older age. These results demonstrate that consideration of a role for COX-2 in normal retinal physiology is warranted, particularly when anti-COX-2 medications are being prescribed
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