Plasma Levels of Matrix Metalloproteinase-9 are Independently Associated With Psychosocial Factors in a Middle-Aged Normal Population

Objective: To test the association between psychosocial factors and circulating levels of matrix metalloproteinase-9 (MMP-9) in a normal population sample. Psychosocial factors have been associated with inflammatory markers and are of prognostic significance for coronary artery disease (CAD). The degrading enzyme MMP-9 is upregulated in inflammatory processes and hypothesized to play a role in the rupture of atherosclerotic plaques. Methods: A total of 402 participants (50% women), aged 45 to 69 years, were drawn randomly from a normal population. Psychosocial instruments covered depression (Center for Epidemiological Studies Depression Questionnaire, CES-D), vital exhaustion, hostile affect, cynicism, mastery, self-esteem, sense of coherence (SOC), emotional support, and social integration. Plasma MMP-9 was measured by an enzyme-linked immunosorbent assay method. Linear regression models were adjusted for age, sex, known CAD, rheumatoid arthritis, cancer, cardiovascular risk factors including C-reactive protein and ongoing medication. Results: After full adjustment, there were independent associations of elevated MMP-9 levels with CES-D (+2.9 ng/ml per SD, p = .02), hostile affect (+3.0 ng/ml per SD, p = .02), cynicism (+3.5 ng/ml per SD, p = .006), and SOC (−2.5 ng/ml per SD, p = .046). A principal component analysis extracted three components. The first was mainly extracted from CES-D, vital exhaustion, self-esteem, mastery, and SOC; the second was mainly extracted from hostile affect and cynicism. Both were independently associated with MMP-9 (p = .02, p = .04) when run in the same model. Conclusions: MMP-9 levels were associated with psychosocial factors in a middle-aged normal population sample, independently of traditional risk factors. The findings may constitute a possible link between psychosocial factors and cardiovascular risk. CAD = coronary artery disease; CES-D = Center for Epidemiological Studies Depression Questionnaire; CRP = C-reactive protein; HDL = high-density lipoprotein; IL = interleukin; IQR = interquartile range; LDL = low-density lipoprotein; LSH = Life conditions, Stress and Health; MMP-9 = matrix metalloproteinase-9; PHCC = Primary Health Care Centre; SOC = sense of coherence; SBP = systolic blood pressure; SD = standard deviation.