Statins decrease cathpsins and MMP 9 activity in human abdominal aortic aneurysms (AAAs) wall

Objectives: Elastolytic activity is an important mechanism in aneurysm formation and expansion. Statins are lipid lowering agents which reduce the expression of elastolytic enzymes in aortic explants and the macrophages. The expansion of experimental aneurysms has been reduced by statin treatment. The aim of this study was to examine the effect of statin treatment on the activity of cathepsins and matrix metalloproteinase-9 in AAA wall.
Methods: Aortic wall biopsies were taken from patients during AAA repair (n= 82). Only 21 patients were on statin treatment before surgery. The activity of cathepsins B, H, K, L, S, and MMP-9 were measured in extracts of AAA wall using quantitative assays. Activity was standardised against the total soluble protein concentrations.
Results: The statin-treated cohort had almost 2-fold lower cathepsin H activity compared with patients not taking statins (controls, P=0.015). Cathepsin L activity was 3-fold lower in the statin-treated cohort compared with controls (P= 0.02). There was a 2-fold reduction in MMP-9 activity the statin-treated cohort compared with controls (P<0.0001). There was also reduction in the activity of cathepsin B, K and S activity in the statin-treated cohort, but these did not reach statistical significance.
Conclusions: Statins decrease the activity of elastolytic enzymes that are known to degrade the extracellular matrix. They may have a role in reducing the expansion of AAA.