Differences in Elastin and Elastolytic Enzymes between Men and Women with Abdominal Aortic Aneurysm

Abdominal aortic aneurysms (AAAs) in women differ in some important aspects from those in men. The lower prevalence rate, higher rupture rate and potentially increased growth rate in women with AAA suggest gender to be of importance for aneurysm development and progression. The aim of the study was to analyze wall properties with respect to synthesis and destruction of elastin in men and women with AAA, with and without an intraluminal thrombus.

Patient characteristics and aneurysm wall biopsies were collected from all women (n = 14) treated with open repair for AAA, 2008-2012, and men with similar aneurysm diameter and similar age (n = 23) treated during the same time period. The expressions of elastin, matrix metalloproteinase (MMP)-2 and -9, and cathepsin K were quantified by immunohistochemistry, Western blot, and gene expression analysis on the aneurysm wall.

The protein expression of elastin was less in women than in men in the non-thrombus-covered aneurysm wall. In addition, the protein and mRNA expressions of MMP-9 were higher in women (-0.83 versus 0.09, P = 0.041). There was no difference in elastin and elastolytic enzymes between men and women in the thrombus-covered aneurysm wall.

Less elastin in the non-thrombus-covered aneurysm wall in women than that in men, and the simultaneous higher level of MMP-9, suggest differences in the elastolytic process in AAA between the sexes.