Plasma concentration, genetic variation, and gene expression levels of matrix metalloproteinase 9 in Iranian patients with coronary artery disease

BACKGROUND: Matrix metalloproteinase 9 (MMP9) -1562C>T (rs3918242) polymorphism has been proposed as a risk factor for coronary artery disease (CAD) with conflicting results. The aim of the present study was to investigate the association of -1562C>T genetic polymorphism, gene expression and circulating levels of MMP9 with CAD risk in an Iranian subpopulation in in Zanjan City. MATERIALS AND METHODS: This was a retrospective case–control study we investigated retrospectively 100 patients with angiographically verified CAD and 100 matched controls. Genotyping of -1562C>T polymorphism was done by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Gene expression levels and circulating levels of MMP9 was determined by real-time reverse transcription-PCR and enzyme immunoassay method, respectively. Statistical analysis was done using Student's t-test or Chi-square test by SPSS 16 software. RESULTS: The mean circulating levels of MMP9 were significantly higher in CAD Group than control group (P = 0.002). Mean plasma levels of MMP9 were also significantly higher in triple vessel stenosis patients than double vessel or single vessel stenosis patients (P < 0.001). Moreover, mean plasma levels and gene expression levels of MMP9 were significantly higher in T allele carrier than C allele carrier of MMP9 -1562C>T polymorphism (P = 0.002, P = 0.01, respectively). However, genotype and allele frequencies of MMP9 -1562C>T polymorphism were similar between CAD patients and controls (P > 0.05). Additionally, the -1562C>T polymorphism of MMP9 gene didn't increase the risk of CAD in dominant (P = 0.537) or recessive (P = 0.249) genetic models. CONCLUSION: Our study demonstrated that circulating levels of MMP9 but not -1562C>T polymorphism of MMP9 gene may be a risk factor for development and severity of CAD in an Iranian subpopulation in Zanjan.