Advanced age-related macular degeneration (AMD) is the leading cause of blindness in the elderly with limited therapeutic options. Here, we report on a study of >12 million variants including 163,714 directly genotyped, most rare, protein-altering variant. Analyzing 16,144 patients and 17,832 controls, we identify 52 independently associated common and rare variants (P < 5×10–8) distributed across 34 loci. While wet and dry AMD subtypes exhibit predominantly shared genetics, we identify the first signal specific to wet AMD, near MMP9 (difference-P = 4.1×10–10). Very rare coding variants (frequency < 0.1%) in CFH, CFI, and TIMP3 suggest causal roles for these genes, as does a splice variant in SLC16A8. Our results support the hypothesis that rare coding variants can pinpoint causal genes within known genetic loci and illustrate that applying the approach systematically to detect new loci requires extremely large sample sizes.

Summary Pathologic angiogenesis mediated by abnormally polarized macrophages plays a central role in common age-associated diseases such as atherosclerosis, cancer and macular degeneration. Here we demonstrate that abnormal polarization in older macrophages is caused by programmatic changes that lead to reduced expression of ATP binding cassette transporter ABCA1. Downregulation of ABCA1 by microRNA-33 impairs the ability of macrophages to effectively efflux intracellular cholesterol, which in turn leads to higher levels of free cholesterol within senescent macrophages. Elevated intracellular lipid polarizes older macrophages to an abnormal, alternatively activated phenotype that promotes pathologic vascular proliferation. Mice deficient for Abca1, but not Abcg1, demonstrate an accelerated aging phenotype, whereas restoration of cholesterol efflux using LXR agonists or miR-33 inhibitors reverses it. Monocytes from older humans with age-related macular degeneration showed similar changes. These findings provide an avenue for therapeutic modulation of macrophage function in common age-related diseases.

PURPOSE. Chemokine signaling and monocytes/macrophages were implicated in the pathogenesis of AMD. We tested the association between chemokines involved in monocyte recruitment and AMD. METHODS.Immunophenotyping for white blood cell (WBC) populations including CD14þþCD16-and CD14þCD16þ monocytes, CD19þ, CD3þ, and CD16þ lymphocytes, and chemokine receptors CCR1, CCR2, CCR5, CX 3 CR1, and CXCR4 was performed on peripheral blood from treatment-naïve neovascular AMD (NV-AMD) patients and controls. The mRNA level of chemokine receptors in monocytes was measured with quantitative-PCR. Systemic levels of major chemokine ligands CCL2, CCL5, CCL3, and CXCL10 were evaluated by ELISA. Genotyping was performed for risk SNPs for AMD in the CFH, C3, and HTRA1 genes. RESULTS.The percentage of WBC subpopulations tested was similar between NV-AMD patients (n ¼ 18) and controls (n ¼ 20). CD14þCD16þ monocyte subpopulation showed a 3.5-fold increased expression of CCR1 (P ¼ 0.039; t-test) and a 2.2-fold increased expression of CCR2 (P ¼ 0.027) in patients compared with controls. Increased CCR1 and CCR2 expression was correlated with each other in patients (R 2 ¼ 0.64, P < 0.0001), but not controls (R 2 ¼ 0.02, P ¼ 0.57). Increased mRNA levels of CCR1 (1.6-fold, P ¼ 0.037) and CCR2 (1.6-fold, P ¼ 0.007) were found in monocytes from NV-AMD patients. Chemokine receptor expression was not correlated with the presence of risk SNPs, and was not associated with blood chemokine levels.CONCLUSIONS. CCR1 and CCR2 are coupregulated on the CD14þCD16þ monocyte population in NV-AMD patients. These data implicate CD14þCD16þ monocytes and chemokine signaling in AMD. Additional investigation is needed to elucidate the role of these monocytes and their potential as a biomarker or therapeutic target for AMD. (Invest Ophthalmol Vis Sci. 2012;53:5292-5300)

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.