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Aden Swayze, Leonie Kurzlechner, Malina Sexton, Alan D Proia, Simone Degan, Eleonora M Lad; Monocyte Biomarkers of Early-Intermediate Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2022;63(7):362 – F0193.
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© ARVO (1962-2015); The Authors (2016-present)
To employ a flow cytometry gating strategy to investigate blood-based monocyte biomarkers of early-intermediate age-related macular degeneration (AMD) and determine the relationship between monocytes and disease stage on flow cytometry and immunohistochemistry (IHC).
We recruited 30 study participants: 9 with early AMD (eAMD; category 2 AREDS), 11 with intermediate AMD (iAMD; category 3 AREDS), and 10 normal controls. Samples were matched by age (+/-5 years) and gender. Peripheral blood mononuclear cells (PBMCs) were isolated from whole blood samples and then stained with CD45, CD14, CD16, CD163, CD11a, and CD11b antibodies. We used a flow cytometry gating strategy to identify PBMC subsets (classical, intermediate, and non-classical). In parallel, we performed co-localization IHC studies of CD163+ and CD68+ macrophages in the macula of postmortem eyes with iAMD (stage Sarks 4; N=7) and normal control eyes (stage Sarks 1; N=7).
On flow cytometry, the proportion of CD68+ cells was lowest in the PBMCs from iAMD participants (52.3% vs eAMD 77.7% and normal 60.9%), and there was a significant difference between the early and iAMD groups (p<0.05). iAMD samples demonstrated the highest percentage of CD163+ cells (8.7% vs eAMD 2.3%, normal 5.3%; p= 0.54) and nonclassical monocytes (5.9% vs eAMD 4.5%, normal 4.4%; p= 0.62), although the results did not reach significance. Within CD68+ and CD163+ cells, there were no significant differences between groups with respect to PBMC subsets. However, we found a moderate correlation between CD163-high cells and the intermediate PBMC subset (r2= 0.35).The quantitative IHC analysis showed a decreased expression of CD163 in the macrophages in the choroid and inner retina of iAMD Sarks 4 postmortem eyes and an increased CD163 expression in the outer retina as compared to normal Sarks 1 eyes (all p<0.05). No significant differences in CD68 expression were observed between the iAMD Sarks 4 and normal Sarks 1 groups.
Our data suggest that CD163+ monocytes/macrophages are associated with disease stage in early-intermediate AMD, implicating these cells in the pathobiology and progression of AMD. CD163 may represent a useful clinical blood-based biomarker of disease progression on flow cytometry analysis.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
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