Characterizing Possible Biomarkers in Ascending Aortic Aneurysms - MMP-2/9 Serum Levels in Patients and Healthy Controls

Objectives: The role of Matrix-Metalloproteinases 2 and 9 (MMP-2/9) in the pathogenesis of ascending aortic aneurysms and its potential as a wall-derived prognostic serum-bio-indicator have not been fully characterized yet. We examined blood serum samples of patients before surgical intervention for ascending and/or root aneurysm and healthy volunteers.

Methods: MMP-2 and MMP-9 levels in the serum of n = 32 patients (aortic root/ascending aorta > = 45 mm, n = 26, [81%] aortic regurgitation, n = 12 [38%] aortic stenosis, n = 3 [9%] normally functioning valve, n = 13 [41%] bicuspid aortic valve) were compared with the levels of n = 19 healthy volunteers. For identification of differences between patients and controls a Wilcoxon rank sum test was used. For statistical analyses focusing on identifying factors impacting on MMP serum levels ANOVA one-way test was used. The influence of aortic diameter in patients suffering from ascending aortic aneurysm on the MMP-2 and MMP-9 levels was examined by Spearman´s rank correlation test in 31 patients.

Results: Patients with aneurysm of the ascending aorta presented significantly lower MMP-2 serum levels when compared with controls, whereas no significant difference for MMP-9 levels was detected (MMP-2 p = 0,001, MMP-9 p = 0,505). Analysis of gender and age, comorbidities such as aortic insufficiency and stenosis, bicuspidity of the aortic valve, obesity, hypertension and hyperlipidemia revealed that only hyperlipidemia was significantly associated with altered MMP-9 level in patients with ascending aortic aneurysm (p = 0,042). In those patients Sartane medication was linked to a significant decrease of serum MMP-9 level (p = 0,01).The ascending aortic diameter was significantly correlated with MMP-2 level (correlation coefficient = 0.373, p = 0.039).

Conclusions: Hyperlipidemia influences MMP-9 level in the serum of patients with ascending aortic aneurysm.

The lower levels of MMP-2 in patients compared with healthy controls suggest a higher binding to matrix components as found in abdominal aortic aneurysm. The correlation between aortic diameter and the MMP- 2 level possibly alludes to higher aortic wall destruction in aneurysms with larger diameters.

Thus this correlation of MMP-2 serum levels with larger diameters should put MMP-2 in the focus of further evaluation as a prognostic biomarker.