Serum concentrations of atherogenic proteins neutrophil gelatinase-associated lipocalin and its complex with matrix metalloproteinase-9 are significantly lower in women with polycystic ovary syndrome: hint of a protective mechanism?

Background: Neutrophil gelatinase-associated lipocalin (NGAL) and matrix metalloproteinase-9 (MMP-9) have been considered as important mediators of vascular remodeling and plaque instability. The formation of a complex with NGAL and MMP-9 is crucial for atherotic plaque erosion and thrombus formation. In women with polycystic ovary syndrome (PCOS), the incidence of cardiovascular clinical events is not increased, despite the fact that they display a wide spectrum of risk factors. Since the instability of atherosclerotic plaque is a key factor in the clinical manifestations of cardiovascular disease, molecules challenging the plaque stability should be investigated. Aim: To determine serum levels of NGAL and MMP-9/NGAL complex in women with PCOS. Subjects and methods: PCOS subjects (40) were compared with those (40) matched for age and body mass index (BMI) controls. In each subject, fasting levels of glucose, insulin, gonadotropins, estradiol, androgens, C-reactive protein, NGAL, and MMP-9/NGAL were determined. Results: NGAL and MMP-9/NGAL complex levels were significantly lower in the PCOS group compared with controls (30.4 +/- 24.3 vs 70.7 +/- 37.9 mu g/l P < 0.0001) and (31.5 +/- 26.6 vs 115.1 +/- 66.9 mu g/l, P < 0.0001) respectively. When patients and controls were stratified according to BMI, it was shown that NGAL and MMP-9/NGAL levels were significantly lower in lean (P < 0.0002 and P < 0.0001 respectively) and overweight (P < 0.0004 and P < 0.002 respectively) PCOS subjects compared with controls. Conclusions: These findings indicate that NGAL and MMP-9/NGAL complex, two molecules that activate atherotic plaque erosion, is in lower concentrations in PCOS subjects. The role of NGAL and MMP-9/NGAL complex needs to be further investigated, since suppression of these atheromatous molecules might have a protective role in women with PCOS.