No abstract

Mononuclear phagocytes (MPs), including monocytes/macrophages, play complex roles in age-related macular degeneration (AMD) pathogenesis. We reported altered gene-expression signature in peripheral blood mononuclear cells from AMD patients, and a chemokine receptor signature on AMD monocytes. To obtain comprehensive understanding of MP involvement, particularly in peripheral circulation in AMD, we performed global gene expression analysis in monocytes. We separated monocytes from treatment-naïve neovascular AMD (nvAMD) patients (n = 14) and age-matched controls (n = 15), and performed microarray and bioinformatics analysis. Quantitative real-time PCR was performed on other sets of nvAMD (n = 25), atrophic AMD (n = 21), and controls (n = 28) for validation. This validated microarray genes (like TMEM176A/B and FOSB) tested, including differences between nvAMD and atrophic AMD. We identified 2,165 differentially-expressed genes (P < 0.05), including 79 genes with log2 fold change ≥1.5 between nvAMD and controls. Functional annotation using DAVID and TANGO demonstrated immune response alterations in AMD monocytes (FDR-P <0.05), validated by randomized data comparison (P < 0.0001). GSEA, ISMARA, and MEME analysis found immune enrichment and specific involved microRNAs. Enrichment of differentially-expressed genes in monocytes was found in retina via SAGE data-mining. These genes were enriched in non-classical vs. classical monocyte subsets (P < 0.05). Therefore, global gene expression analysis in AMD monocytes reveals an altered immune-related signature, further implicating systemic MP activation in AMD.

Purpose Age-related macular degeneration (AMD) is associated with altered gene and protein expression in the retina. We characterize the aqueous humor (AH) proteome in AMD to gain insight into the pathogenesis of the disease and identify potential biomarkers. Methods AH was collected from age and gender matched neovascular AMD (nvAMD; n = 10) patients and controls ( n = 10). AH was pooled to create two samples (nvAMD and control), followed by intensity-based label-free quantification (MS1). Functional and bioinformatic analysis were then performed. A validation set (20 controls, 15 atrophic AMD and 15 nvAMD) was tested via multiplex ELISA for nine differentially expressed proteins according to the MS1 findings. Results MS1 identified 674 proteins in the AH. 239 proteins were upregulated in nvAMD (nvAMD/control > 2, peptide tags (PT) > 2), and 86 proteins were downregulated (nvAMD/control < 0.5, PT > 2). Functional analysis of proteins upregulated in AMD demonstrated enrichment for platelet degranulation (enrichment score (ES):28.1), negative regulation of endopeptidase activity (ES:18.8), cellular protein metabolic process (ES:11.8), epidermal growth factor-like domain (ES:10.3), sushi/SCR/CCP (ES:10.1), and complement/coagulation cascades (ES:9.2). AMD protein clusters were upregulated for 3/6 (χ2 < 0.05 compared to randomization). Validation via ELISA confirmed MS1 in 2/9 proteins (Clusterin and Serpin A4, P < 0.05), while 3/9 showed differential expression between aAMD and nvAMD (Clusterin, Serpin A4, and TF P < 0.05). Receiver operating characteristic curve calculation identified the area under the curve of 0.82 for clusterin as a biomarker for distinction of AMD. Conclusions AH proteomics in AMD patients identified several proteins and functional clusters with altered expression. Further research should confirm if these proteins may serve as biomarkers or therapeutic target for the disease.

Anti-vascular endothelial growth factor (VEGF) therapy for neovascular AMD (nvAMD) obtains a variable outcome. We performed a genome-wide association study for anti-VEGF treatment response in nvAMD to identify variants potentially underlying such a variable outcome. METHODS. Israeli patients with nvAMD who underwent anti-VEGF treatment (n = 187) were genotyped on a whole exome chip containing approximately 500,000 variants. Genotyping was correlated with delta visual acuity (deltaVA) between baseline and after three injections of anti-VEGF. Top principal components, age, and baseline VA were included in the analysis. Two lead associated variants were genotyped in an independent validation set of patients with nvAMD (n = 108). RESULTS. Linear regression analysis on 5,353,842 variants revealed five exonic variants with an association P value of less than 6 × 10 −5. The top variant in the gene VWA3A (P = 1.77 × 10 −6) was tested in the validation cohort. The minor allele of the VWA3A variant was associated with worse response to treatment (P = 0.02). The average deltaVA of discovery plus validation was-0.214 logMAR (≈ a gain of 10.7 Early Treatment Diabetic Retinopathy Study letters) for homozygote for the major allele, 0.172 logMAR for heterozygotes (≈ a loss of 8.6 Early Treatment Diabetic Retinopathy Study letters), and 0.21 logMAR for homozygote for the minor allele (≈ a loss of 10.5 Early Treatment Diabetic Retinopathy Study letters). Minor allele carriers had a higher frequency of macular hemorrhage at baseline. CONCLUSIONS. An VWA3A gene variant was associated with worse response to anti-VEGF treatment in Israeli patients with nvAMD. The VWA3A protein is a precursor of the multimeric von Willebrand factor which is involved in blood coagulation, a system previously associated with nvAMD.

Background. Age-related macular degeneration (AMD), the most common cause of blindness in the developed world, usually affects individuals older than 60 years of age. The majority of visual loss in this disease is attributable to the development of choroidal neovascularization (CNV). Mononuclear phagocytes, including monocytes and their tissue descendants, macrophages, have long been implicated in the pathogenesis of neovascular AMD (nvAMD). Current therapies for nvAMD are based on targeting vascular endothelial growth factor (VEGF). This study is aimed at assessing if perturbation of chemokine signaling and mononuclear cell recruitment may serve as novel complementary therapeutic targets for nvAMD. Methods. A promiscuous chemokine antagonist (BKT130), aflibercept treatment, or combined BKT130+aflibercept treatment was tested in an in vivo laser-induced model of choroidal neovascularization (LI-CNV) and in an ex vivo choroidal sprouting assay (CSA). Quantification of CD11b+ cell in the CNV area was performed, and mRNA levels of genes implicated in CNV growth were measured in the retina and RPE-choroid. Results. BKT130 reduced the CNV area and recruitment of CD11b+ cells by 30-35%. No effect of BKT130 on macrophages’ proangiogenic phenotype was demonstrated ex vivo, but a lower VEGFA and CCR2 expression was found in the RPE-choroid and a lower expression of TNFα and NOS1 was found in both RPE-choroid and retinal tissues in the LI-CNV model under treatment with BKT130. Conclusions. Targeting monocyte recruitment via perturbation of chemokine signaling can reduce the size of experimental CNV and should be evaluated as a potential novel therapeutic modality for nvAMD.