Genetic variations and plasma levels of gelatinase A (matrix metalloproteinase-2) and gelatinase B (matrix metalloproteinase-9) in proliferative diabetic retinopathy

PURPOSE Matrix metalloproteinases (MMPs) are postulated to be involved in the development of retinal angiogenesis through the regulation of extracellular matrix. The objective of the present study was to test for a possible association of five single nucleotide polymorphisms (SNPs) in the MMP-2 gene and two polymorphisms in the MMP-9 gene with proliferative diabetic retinopathy (PDR) and to determine their plasma levels. METHODS The study comprised 490 Caucasian participants, who were divided into three groups: diabetics with PDR, diabetics without PDR, and nondiabetics. Genotypes were detected by polymerase chain reactions followed by restriction analyses with specific endonucleases and their frequencies determined. Plasma levels of MMP-2 and MMP-9 proteins were analyzed by ELISA. RESULTS Neither MMP-2 SNPs nor MMP-9 SNPs revealed significant association with PDR in single-locus comparisons; similarly, MMP-2 haplotype frequencies did not differ notably between groups, although the C-allele of the -1306C/T polymorphism and the C-allele containing haplotype (CGCG) in MMP-2 exhibited marginally significant association with PDR in males (p<0.05, p(corr)=NS). Both MMP-2 and MMP-9 plasma levels showed statistically significant differences among the studied groups (p<0.001 and p=0.001, respectively) with highest levels in the PDR group. MMP-2 plasma levels were markedly higher in carriers of either the -1306CC and -1306CT genotypes and (p=0.009) or CGCG haplotype (p=0.043). CONCLUSIONS These findings indicate that genotype- and haplotype-specific effects on MMP-2 expression corresponding with its plasma levels may contribute to the susceptibility to PDR.