Association of gene polymorphism with serum levels of inflammatory and angiogenic factors in Pakistani patients with age-related macular degeneration.
OBJECTIVE
To study the association of serum levels of inflammatory mediators and angiogenic factors with genetic polymorphism in Pakistani age-related macular degeneration (AMD) patients.


METHODS
This was a cross-sectional and case-control study that included 90 AMD patients diagnosed through slit-lamp examination, fundoscopy, and ocular coherence tomography. For reference and comparison purposes, 100 healthy age-matched subjects (controls) were also recruited. IL-6, IL-8, VEGF, and CRP levels were estimated in the serum samples of patients and control subjects. Using restriction fragment length polymorphism, single nucleotide polymorphisms were studied in IL-6 (rs1800795, rs1800796, rs1800797), IL-8 (rs4073, rs2227306, rs2227543), VEGF (rs3025039, rs699947), and CRP genes (rs1205, rs1130864). Since the data were obtained from a sample population, the Box-Cox transformation algorithm was applied to reduce heterogeneity of error. Multivariate analyses of variance (M-ANOVA) were applied on the transformed data to investigate the association of serum levels of IL-6, IL-8, VEGF, and CRP with AMD. Genotype and allele frequencies were compared through χ(2) tests applying Hardy-Weinberg equilibrium. The serum concentrations of IL-6 and IL-8, VEGF, and CRP between homozygotes and heterozygotes were compared through one-way ANOVA. Significance level was p<0.05.


RESULTS
Compared to control subjects, serum IL-6 (p<0.0001), IL-8 (p<0.0001), VEGF (p<0.0001), and CRP (p<0.0001) levels were significantly elevated in the AMD patients. For rs1800795, patients with the GG genotype showed significantly raised levels of IL-6 compared to those with GC and CC genotypes (p<0.0001). Serum IL-8 levels were significantly higher in patients with the GG genotype compared to the GC and CC genotypes for the single nucleotide polymorphism (SNP) rs2227543 (p<0.002). Similarly, significantly higher VEGF levels were detected for genotype TT for rs3025039 SNP (p<0.038). However, no significant alteration in serum CRP levels was detected in hetero- or homozygotes for rs1205 and rs1130864 SNPs.


CONCLUSIONS
Serum IL-6, IL-8, and VEGF levels are substantially increased in AMD, and the levels coincide with polymorphism in the respective gene. No such relationship appears to exist with regard to SNPs of CRP.
Laboratory of Animal and Human Physiology, Quaid-i-Azam University, Islamabad, Pakistan.
Fareeha
F
Ambreen
Institute of Biomedical and Genetic Engineering, Islamabad, Pakistan.
Muhammad
M
Ismail
Laboratory of Animal and Human Physiology, Quaid-i-Azam University, Islamabad, Pakistan.
Irfan Zia
IZ
Qureshi
D000368:Aged; D000369:Aged, 80 and over; D042501:Angiogenic Proteins / Q000097:blood*; D002097:C-Reactive Protein / Q000235:genetics / Q000378:metabolism; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D056726:Genetic Association Studies; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood / Q000235:genetics; D016209:Interleukin-8 / Q000097:blood / Q000235:genetics; D008268:Macular Degeneration / Q000097:blood* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D010154:Pakistan; D020641:Polymorphism, Single Nucleotide; D042461:Vascular Endothelial Growth Factor A / Q000097:blood / Q000235:genetics
D042501:Angiogenic Proteins; C508606:CXCL8 protein, human; C508600:IL6 protein, human; D018836:Inflammation Mediators; D015850:Interleukin-6; D016209:Interleukin-8; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D002097:C-Reactive Protein