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Nan Yang, Judith Lechner, Ruth E Hogg, Levente Toth, Giuliana Silvestri, Usha Chakravarthy, Mei Chen, Heping Xu; Plasma level of lipocalin-2 is increased in neovascular age-related macular degeneration, particularly in patients with macular fibrosis. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1626. doi: https://doi.org/.
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Previously we have shown that the population of circulating neutrophil is increased in neovascular age-related macular degeneration (nAMD). The aim of this study was to investigate the plasma level of neutrophil gelatinase-associated lipocalin (NGAL, or lipocalin-2, LCN2) and metalloproteinase 9 (MMP9), a regulatory factor of neutrophil transmembrane migration, and MMP9/LCN2 complex in different types of nAMD.
Two hundred and thirteen participants older than 50 years of age, including 170 nAMD and 43 controls were enrolled from the retina clinics in Belfast. Clinical information, on gender, hypertension, diabetes, medication, smoking habits, family history of AMD and body mass index (BMI) etc., were collected using a structured questionnaire. AMD subtypes, the presence/absence of macular fibrosis and macular atrophy were evaluated using color and fluorescein images, AF and OCT images. Plasma samples were collected and stored at -80°C for the measurement of LCN2, MMP9, and MMP9/LCN2 using commercial human enzyme-linked immunosorbent assay (ELISA) kits.
The plasma level of LCN2, but not MMP9 or MMP9/LCN2 was significantly higher in nAMD patients compared to that in healthy controls. LCN2 positively correlated with the percentage of circulating neutrophils in nAMD patients but not in controls. Further analysis of different types of nAMD showed significantly higher levels of LCN2 in CNV (n = 170) but not retinal angiomatous proliferation (RAP, n = 32) or polypoidal choroidal vasculopathy (PCV, n = 23) compared to that in controls. nAMD patients with fibrosis (n = 58) had significantly higher levels of LCN2 compared to controls in both univariate (p=0.015) and multivariate (after adjusting for age, p=0.033). There was no significant difference in the levels of LCN2 in patients with and without macular atrophy.
Our results suggest that higher levels of circulating neutrophils that are present in patients with nAMD may be responsible for increased plasma levels of LCN2. Our results also suggest that higher plasma level of LCN2 is associated with macular fibrosis in nAMD. The role of LCN2 in macular fibrosis warrants further investigation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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