Plasma Cathepsin S is Associated with High-density Lipoprotein Cholesterol and Bilirubin in Patients with Abdominal Aortic Aneurysms

BACKGROUND: Cathepsin S (CTSS) is a cysteine protease involved in atherogenesis. We compared the plasma CTSS as well as other biomarkers of atherosclerosis in patients with abdominal aortic aneurysms (AAA) and aortoiliac occlusive disease (AOD), aiming to identify the underlying pathogenic mechanisms of the disease development. Also, we hypothesised that the level of plasma CTSS simultaneously increases with a decrease of plasma high-density lipoprotein cholesterol (HDL-C) values. METHODS: 33 patients with AAA and 34 patients with AOD were included in this study. RESULTS: There was no difference in the level of plasma CTSS between the two analysed groups (p=0.833). In the patients with AAA, the plasma CTSS was correlated with HDL-C (r = -0.377, p = 0.034) and total bilirubin (r =0.500, p = 0.003) while, unexpectedly, it was not correlated with cystatin C (Cys C) (r =0.083, p = 0.652). In the patients with AOD, the plasma CTSS correlated with triglycerides (r = 0.597, p< 0.001), only. When the patients were divided according to HDL-C (with HDL-C ≤0.90 and HDL-C >0.90 mmol/L), the plasma CTSS values differed among these groups (31.27 vs.25.61 μg/L, respectively, p<0.001). CONCLUSIONS: These results provide the first evidence that CTSS negatively correlated with HDL-C and bilirubin in patients with AAA. It is possible that differences in the association of the CTSS and other markers of atherosclerosis can determine whether atherosclerotic aorta will develop dilatation or stenosis.