Enhanced serum myeloperoxidase level correlates with clinical features of Parkinson's disease

Objectives. Myeloperoxidase (MPO) has been implicated in Parkinson´s disease (PD). The objective was to look at the relationship of MPO concentration in serum and cerebrospinal fluid (CSF) with clinical variables of PD. Methods. In this prospective, observational, and cross-sectional study, MPO concentration in serum and the CSF was analyzed in 36 patients with idiopathic PD and 30 controls, who were enrolled from 2012 to 2017. In the group of patients, correlation of MPO content with demographic, clinical and tomographic variables was examined. The extent and degree of nigrostriatal dopaminergic cell loss was evaluated by using SPECT and 123I-Ioflupane, radioligand that has binding affinity for dopamine-transporter (DAT). Results. Serum MPO concentration, not CSF MPO content, was significantly higher in the patients (p<.0001). Significant correlation values were found between serum MPO concentration and rating scales of motor severity (Hoehn-Yahr, MDS-UPDRS part-III), and percentage reduction of DAT binding on basal ganglia (p<.0001). Patients with moderate-advanced disease (Hoehn-Yahr stage 3) showed significantly higher serum MPO content relative to patients with early disease (Hoehn-Yahr stages 1-2, p<.0001). DAT binding was reduced on all striatal regions, and signal reduction was higher in the putamen relative to the caudate nucleus (p<.0001). Percentage reduction of DAT binding on the striatum and putamen significantly correlated with rating scales of motor severity. Conclusions. Myeloperoxidase content in serum is increased in PD patients and correlates with motor severity degree and loss of dopamine-transporter binding on basal ganglia. The results allow proposing that the measurement of MPO level in serum could be useful for PD diagnosis, and that the inhibition of serum MPO would be a promising therapeutic tool. The study also confirms that the putamen shows higher reduction of DAT binding than the caudate nucleus, and degree of nigrostriatal dopaminergic cell loss is well quantified with rating scales of motor severity.