Association between serum myeloperoxidase enzyme activity and Parkinson's disease status

Elevated levels of the inflammatory enzyme myeloperoxidase (MPO) in the blood are associated with the development of age-related inflammatory diseases. Given that age, inflammation, and blood MPO play a role in the pathogenesis of Parkinson´s disease (PD), we hypothesized that serum MPO could be associated with PD status. This case-control study (199 participants) was conducted using an extensive protocol, and the concentration and activity of MPO in blood serum were measured. The findings reveal that serum MPO concentration and activity are significantly increased in the patients, and that rates of PD in all individuals are associated with increasing tertiles of MPO concentration and activity. In multivariate logistic regression model adjusting for confounding factors, MPO activity (not concentration) is the factor that is most associated with PD status (OR, 6.921, P = 0.001). Mental depression is directly associated with MPO activity and with PD status (OR, 0.121, B = -2.108, P = 0.002). The use of statins or nonsteroidal anti-inflammatory drugs significantly reduces serum MPO activity, but the possible association with the odds of having PD does not survive correction for multiple testing. In summary, both serum MPO concentration and activity are increased in patients with PD, but only MPO enzyme activity is associated with PD status. These findings may have implications for the evaluation of PD.