Plasma levels of DJ-1 as a possible marker for progression of sporadic Parkinson's disease.

DJ-1 is a multifunctional protein whose loss of function by gene mutations may play a causative role for familial Parkinson's disease (PD). A recent study has shown that the expression of this molecule is upregulated in both brains and cerebrospinal fluids (CSF) in various neurological disorders, including sporadic PD, Alzheimer's disease (AD) and stroke, raising a possibility that DJ-1 could be a potential biomarker for these diseases. In this context, the main objective of the present study was to determine if DJ-1 was increased in the plasma of PD patients. For this purpose, blood plasma samples collected from sporadic PD patients, dementia with Lewy bodies (DLB) and healthy age-matched controls were analyzed by immunoblotting and enzyme-linked immunosorbent assay. The results showed that the plasma DJ-1 levels in PD (n=104) were higher than those in control (n=80) (p<0.05). Moreover, the plasma DJ-1 levels in the advanced stage of PD (n=52, Yahr III-IV) were higher than those in the early stage of PD (n=52, Yahr I-II) (p<0.05), demonstrating that the plasma DJ-1 was correlated with the disease severity in PD. Plasma DJ-1 levels were also significantly higher in DLB (n=30) compared with both controls and early stage of PD (p<0.01). Taken together, these results suggest that the plasma DJ-1 could be a useful biomarker for the evaluation of the disease severity in PD and possibly in other Lewy body diseases.