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.