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Vivienne Fang, Vaishali Oza, Sandra S Stinnett, Lejla Vajzovic, Cynthia A Toth, Scott W Cousins, Eleonora M Lad; Monocyte-related biomarkers of intermediate age-related macular degeneration. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2976. doi: https://doi.org/.
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The purpose of this study was to develop a flow cytometry gating strategy to investigate blood-based monocyte biomarkers of intermediate age-related macular degeneration (AMD) and determine the relationship between monocytes and structural biomarkers of disease progression on SD-OCT.
We recruited 14 patients with intermediate AMD (category 3 AREDS) and 8 normal, age-matched control subjects, enrolled as part of a prospective, observational cohort study of early AMD (NCT01822873). Subjects underwent a dilated fundus examination and retinal imaging. Peripheral blood mononuclear cells (PBMCs) were isolated from whole blood samples, and the samples were enriched for monocytes. The cells were stained with CD45, CD14, CD16 and CD163 antibodies and underwent flow cytometry analysis. In parallel, we performed high resolution SD-OCT and slit lamp ophthalmoscopy (SLO) on 36 postmortem eyes (22 intermediate AMD and 14 control eyes) from 22 subjects, using a custom probe specifically designed for use in autopsy eyes. The eyes were then processed for immunohistochemistry analysis of macrophage subpopulations.
We have developed a flow cytometry gating strategy using the pan-monocytic marker CD45 to reliably identify PBMC subsets (classical, intermediate, and non-classical) using CD14 and CD16 expression. We found a significant difference in CD163 expression in the intermediate monocyte subset in patients with intermediate AMD vs. control patients (p=0.036 via a 2-sided Mann-Whitney U test). In postmortem intermediate AMD eyes imaged by SD-OCT and SLO, subretinal CD163+ macrophages had a morphology consistent with that of reticular pseudodrusen, a structural biomarker of disease progression.
Our study suggests that CD163+ cells are associated with structural biomarkers of disease progression and may represent a useful clinical blood-based biomarker on flow cytometry analysis.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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