Serum myeloperoxidase chlorinating activity in acute ischemic stroke

Abstract

Beyond traditional risk factors, inflammation is believed to play a role in the development of ischemic stroke (IS). During inflammation neutrophil leukocytes degranulate, thereby releasing the enzyme myeloperoxidase (MPO) into extracellular space. In addition to peroxidase activity, MPO expresses also a chlorinating activity, and catalyzes the formation of hypochlorous acid and long-lived oxidants - chloramines. In this study we assessed serum chlorinating MPO activity and concentration of total chloramines. We included 29 patients with acute IS, aged 69.0 years (64.2 - 78.0) and 25 control subjects without IS, aged 69.0 years (67.0 - 72.0). It was found that neutrophil cell count was higher in IS than in controls (4.56 ± 1.76 vs. 7.74 ± 3.35 × 109/L, in control and IS group, respectively; p< 0.05). Serum chlorinating MPO activity was also higher in IS group than in controls (67.2 U/L vs. 92.3 U/L, in controls and in patients, respectively; p < 0.05). Concentration of total chloramines was higher in IS group than in controls, but the difference did not reach statistical significance (p=0.178). MPO activity was significantly correlated with serum triglycerides (p<0.05). There was no statistically significant correlation between chlorinating MPO activity and chloramines (p=0.402), while correlations between MPO activity and neutrophil cell count (p=0.071), and MPO activity and the presence of arrhythmia (p=0.094) were both of borderline significance. These results indicate that MPO may be implicated in pathogenesis of IMU, which could be partly due to chlorination of biologically important molecules within vascular compartment.

Keywords

• ischemic stroke
• myeloperoxidase
• chlorinating activity
• chloramines
• inflammation