Plasma matrix metalloproteinase-9 levels, MMP-9 gene haplotypes, and cardiovascular risk in obese subjects.
Plasma matrix metalloproteinase (MMP)-9 is a predictor of cardiovascular mortality, and MMP-9 polymorphisms affect plasma MMP-9 levels. However, no study examined whether MMP-9 haplotypes affect MMP-9 levels in obese adults. We examined whether MMP-9 polymorphisms and haplotypes are associated with obesity, and whether they affect MMP-9 levels in obese subjects. We examined the plasma levels of MMP-9 and tissue inhibitor of metalloproteinase (TIMP)-1 in 105 subjects with normal weight (controls), 100 obese subjects, and 156 obese subjects with ≥3 metabolic risk factors (MRFs). We determined genotypes for three polymorphisms: C-1562T (rs3918242), Q279R (A>G, rs17576), and R668Q (G>A, rs17577). MMP-9 levels and activity (MMP-9/TIMP-1 ratio) were higher in obese subjects than in controls (P < 0.05). However, MMP-9 levels were higher in obese subjects with ≥3 MRFs than in obese subjects (P < 0.05). Obese subjects with ≥3 MRFs carrying the GA+AA genotypes for R668Q (G>A) polymorphism had higher MMP-9 levels than subjects carrying the AA genotype (P < 0.05). The "T, G, A" haplotype was more common in both groups of obese subjects than in controls (OR 3.95 and 4.39, respectively; P < 0.01). Notably, obese subjects with ≥3 MRFs carrying the "T, G, A" haplotype had higher MMP-9 levels than subjects carrying the "C, A, G" reference haplotype (P < 0.05). The "T, G, A" haplotype was associated with an increased risk of obesity and affected MMP-9 levels in obese subjects with ≥3 MRFs. Our findings suggest that plasma MMP-9 levels and MMP-9 haplotypes may help to discriminate obese subjects at an increased cardiovascular risk.