Biochemical Analysis and Genetic Polymorphism of Angiogenic Factors and Inflammatory Markers in Pakistani Patients with Age-Related Macular Degeneration

Abstract

Age related macular degeneration (AMD) is an ophthalmic disease with complex aetiologyand is considered to be one of the major reasons of blindness in aged population. Inflammatory processes are suggested to play an important role in AMD pathogenesis and its progression. The present cross sectional and case-control study was carried out to investigate the role of inflammatory markers and angiogenic growth factors in AMD pathogenesis. Diagnosis was done through slit lamp examination, OCT and FFA. Normotensive and non-diabetic subjects aged ≥50 years diagnosed with AMD were selected. Age matched healthy individuals with no symptoms of AMD were selected as controls. Serum lipids, apolipoprotein E (ApoE), leptin, HTRA1, interleukin 6 (IL-6), IL-8, vascular endothelial growth factor (VEGF), C-reactive protein (CRP) and complimentary factor H (CFH) were determined in patients and controls. Genotype analyses of single nucleotide polymorphisms (SNPs) in IL-6 gene (rs1800795; rs1800796; rs1800797); IL-8 gene (rs4073; rs2227306; rs2227543); VEGF gene (rs3025039; rs699947) and CRP gene (rs1205; rs1130864) were done through restriction fragment length polymorphism. Data were computed through SPSS version 18.0 (Chicago, Illinois, USA) and Graph Pad Prism (GraphPad Software, San Diego, California, USA). Data sets were compared between control and AMD patients through student’s t-test. Genotype and allele frequencies were compared through χ 2 . Significance level was p<0.05. Since the data were obtained from a sample population, to reduce heterogeneity of error, Box-Cox transformation algorithm was applied. Multivariate analysis of variance (M-ANOVA) was applied on the transformed data to investigate association of serum levels of IL-6, IL-8, VEGF and CRP with AMD. Transformed data showed elevated serum levels of IL-8 (p<0.015) and VEGF (p<0.0108) and reduced ApoE (p<0.032) in AMD patients compared to control subjects. Serum VEGF levels were significantly raised (p<0.0001) in wet AMD patients compared to the dry AMD patients. The IL-6 levels were significantly high in patients with genotype GG for rs4073(p<0.0001). IL-8 levels were significantly high in patients with genotype GG for rs2227543(p<0.002). Significantly high VEGF levels were observed in patients xwith genotype TT for rs3025039(p<0.038). CRP levels did not change significantly with respect to genotype forrs1205 and rs1130864. The study concludes that inflammatory markers and angiogenic growth factors are significantly altered in AMD pathogenesis. Significant findings of the present study which are pertinent to mention is that altered levels of inflammatory markers and angiogenic factors are related to the genetic polymorphism for IL-6, IL-8 and VEGF genes. However, SNPs in relation to CRP were not related to serum CRP levelsin AMD patients.