Combined Cathepsin S and hs-CRP predicting inflammation of abdominal aortic aneurysm

Cathepsin S (Cat S) protein expression is increased in human abdominal aortic aneurysm (AAA) lesions and Cat S has been suggested a direct role by promoting inflammatory response partly in experimental AAA. The purpose of this study is to observe the expression of serum Cat S and hs-CRP and its clinical significance in AAA patients.

We collected serum samples from 31 AAA patients and 32 controls. Cat S and hs-CRP levels were measured by a sandwich-type enzyme-linked immunosorbent assay (ELISA) and an enhanced immunoturbidimetric assay respectively. The maximum diameter of the AAA was identified by ultrasonography.

The patients with AAA had higher serum Cat S and hs-CRP levels than the controls (p<0.05). Furthermore, human serum Cat S levels were strongly correlated with hs-CRP by the nonparametric Spearman correlation tests (B=0.849, p<0.05). Based on Pearson's correlation test, human serum Cat S and hs-CRP levels were positively correlated with AAA diameter size (p<0.05). Cat S was correlated independently with the hs-CRP in all subjects (p<0.01). After adjustment for the maximum diameter of the abdominal aorta-associated variables, Cat S combined hs-CRP (R(2)=0.801) is better than Cat S (R(2)=0.740) in predicting the maximum diameter of AAA lesions.

Combined serum Cat S and hs-CRP levels are better in predicting the inflammatory activity of AAA lesions in the clinical setting.