Does lipoprotein(a) inhibit elastolysis in abdominal aortic aneurysms?

Area of Science:

• Cardiovascular Research
• Biochemistry
• Vascular Biology

Background:

• Abdominal aortic aneurysms (AAA) are characterized by the degradation of the aortic wall.
• Matrix metalloproteinases (MMPs), particularly MMP-9, play a crucial role in this degradation process.
• Lipoprotein(a) (Lp(a)) is an independent risk factor for cardiovascular disease, but its role in AAA pathogenesis is not fully understood.

Purpose of the Study:

• To investigate the association between serum levels of lipoprotein(a) (Lp(a)) and markers of aortic wall degradation in patients with asymptomatic abdominal aortic aneurysms (AAA).
• Specifically, to test the hypothesis of a negative association between Lp(a) and elastin-derived peptides (EDP) and matrix metalloproteinase-9 (MMP-9) activation in the AAA wall.

Main Methods:

• Serum samples and AAA biopsies were collected from 30 patients undergoing surgery for asymptomatic AAAs.
• Serum Lp(a) and EDP levels were quantified using enzyme-linked immunosorbent assays.
• MMP-9 activity and the ratio of active to total MMP-9 in AAA wall tissue were determined by gelatin zymography.

Main Results:

• A significant negative correlation was observed between serum Lp(a) levels and serum EDP levels (Spearman's rho = -0.707, p<0.001).
• Serum Lp(a) levels also showed a significant negative correlation with the share of activated MMP-9 in the AAA wall (Spearman's rho = -0.461, p=0.01).

Conclusions:

• This preliminary study suggests that Lp(a) may have a protective role in asymptomatic AAA.
• The findings indicate that Lp(a) might inhibit elastolysis, the degradation of elastin, within the aneurysm wall.