Tissue kallikrein is related to the severity of coronary artery disease

Background The impairment of the tissue kallikrein (KLK1)–kinin system (KKS) may result in atheroma development. However, it remains unclear if the KKS correlates with coronary artery disease (CAD). Methods KLK1, VEGF and hs-CRP plasma levels were measured in 100 patients newly diagnosed with CAD and 33 CAD-free controls. Patients were followed-up for the incidence of major adverse cardiovascular events (MACE) for 8 months to 2 y. Gene expression of KLK1, CD105 and CD68 was assessed in human coronary endarterectomy specimens. Results Patients with CAD and acute coronary syndrome (ACS) had significantly elevated KLK1 levels. In addition, the concentration of hs-CRP was increased in ACS patients. A strong positive correlation between plasma KLK1 and the severity of CAD was also demonstrated, suggesting that high KLK1 levels are an independent predictor for CAD. MACE during follow-up significantly correlated with KLK1 levels in the ACS group. Unstable coronary plaques demonstrated markedly increased KLK1 levels, macrophage infiltration and high microvessel density. Additionally, KLK1 staining primarily colocalized with macrophages. Conclusions In the present study, plasma KLK1 levels were a useful predictor for the presence and extent of CAD. More extensive studies are, however, necessary in order to validate these findings.