Effects of age on plasma matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs)

Abstract

Background: The mechanisms causing age-dependent changes in left ventricular (LV) structure and function are not completely understood. Matrix metalloproteinase (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) constitute one important proteolytic pathway affecting LV remodeling. However, whether these determinants of extracellular matrix (ECM) composition change as a function of age has not been examined in an aging population free of clinically significant cardiovascular disease.

Methods and results: Subjects (n = 77, age 20-90 years) with no evidence of cardiovascular disease underwent echocardiography and measurement of plasma MMP-2, 7, 8, and 9 and TIMP-1, 2, and 4 (enzyme-linked immunosorbent assay). As subject age increased, volume/mass ratio decreased and mitral E/A ratio decreased. As subject age increased, MMP-2 increased (from 1188 +/- 99 ng/mL to 1507 +/- 76 ng/mL), MMP-7 increased (from 1.2 +/- 0.1 ng/mL to 3.1 +/- 0.6 ng/mL), MMP-9 decreased (from 29 +/- 7 ng/mL to 8 +/- 2 ng/mL), and TIMP-1, 2, and 4 increased (from 728 +/- 46 ng/mL to 1093 +/- 73 ng/mL, from 34 +/- 5 ng/mL to 53 +/- 6 ng/mL, and from 1.26 +/- 0.22 ng/mL to 2.34 +/- 0.30 ng/mL, respectively) (all P < .05). There were significant correlations between decreased LV volume/mass and E/A ratio and increased MMP-7 and TIMP-1 and 4.

Conclusions: MMPs and TIMPs changed as a function of age in the absence of clinically significant cardiovascular disease. These age-dependent alterations in MMP and TIMP profiles favor ECM accumulation and were associated with concentric remodeling and decreased LV diastolic function. Because of these age-dependent changes in this proteolytic system, the superimposition of disease processes such as myocardial infarction or hypertensive heart disease in the older subject may result in different myocardial ECM remodeling than that seen in a younger subject.

Figure 1

Relationship between TIMP-1 and the left ventricular (LV) volume to mass ratio. As TIMP-1 increased the volume/mass ratio decreased (y = − 434x + 1244, p = 0.02, r = 0.3)

Figure 2

Relationship between TIMP-1 and the mitral E/A ratio. As TIMP-1 increased the E/A ratio decreased (y = −196x +1161, p = 0.001, r = 0.4)

Figure 3

Relationship between TIMP-1 and age for men vs. women examined using an analysis of covariates. TIMP-1 increased in both men and woman as a function of increasing age. However, the slope of the TIMP-1 vs. age relationship in men (y= 9.5x + 587, r= 0.6) was significantly steeper then that for women (y= 4.6x + 622, r= 0.4), p < 0.05.