Study Of The Relationship Between Deep Brain Stimulation Therapy For Parkinson's Disease And Variation Of Proteins Expression In Cerebrospinal Fluid

Background:Parkinson's disease(PD) is one of the common neurodegenerative disorders characterized by a progressive loss of dopaminergic neurons in the substantia nigra,striatum and putamen,resulting in extrapyramidal motor dysfunction, including resting tremor,rigidity,bradykinesia and postural instability.The pathogenesis of PD is not yet clear.Increasing evidence has suggested that degeneration and loss of dopaminergic neurons in the substantia nigra have links with abnormal protein aggregation.The clinical diagnosis of PD is based entirely on clinical features.There is no special biomarker for PD in diagnosis and differential diagnosis.PD related proteins are becoming research hotspot in recent years. However,the reports on PD related proteins in cerebrospinal fluid(CSF) to date are rare,and there is no report yet on this field in China.As one of the surgical method for PD therapy,deep brain stimulation(DBS) is safe,effective,adaptable,and reversible,and increasingly being used across the world since 1987.However,its primary mechanisms of action are yet poorly understood.It has been known that proteins play important roles in pathological processes of PD.Up to now,there is still no research to report whether DBS has effects on proteins in CSF.Objectives:To compare protein profiles in the CSF between PD patients and control subjects and to identify the PD-related proteins that might serve as potential biomarkers or clues for diagnosis or pathogenesis.Moreover,to quantitate the variation of protein expression in CSF pre-DBS and post-DBS to explore the mechanisms of DBS for the treatment of PD.Evaluating possible relations between the variations of protein expressions in CSF pre- and post-DBS and the Unified Parkinson's Disease Rating Scale(UPDRS) motor scores and activities of daily living (ADL) scores to find out potential biological markers for monitoring the efficacy of DBS.Methods:The CSF from 9 PD patients,8 control subjects,and 5 DBS patents was studied for the differentially expressed proteins in patients with PD compared with controls,in pre-DBS patients compared with post-DBS by two-dimensional difference gel electrophoresis(2D DIGE) technique,in combination with matrix-assisted laser desorption/ ionization- time of flight(MALDI-TOF) and tandem(TOF-TOF) mass spectrometry or electrospray ionization tandem mass spectrometry(ESI-MS- MS). Western-blotting was used to validate the data of proteomic analysis.The motor scores and ADL scores of UPDRS for 5 DBS patients were valuated on the day before operation and the 7^th day after chronic stimulation starting(stimulator on) in state of ON medication and OFF medication respectively.Statistic analysis on UPDRS scores were performed for improvement.Results:Micro-lesioning effects were observed during operation in all 5 patients with PD.The scores of motor and ADL were significantly improved after DBS in both on-medication and off-medication condition.DIGE analysis showed that the levels of 20 protein spots were significantly altered in PD CSF when average ratio of the matched spot was assigned as＞1.5 or＜-1.5.Of which,11 spots were up-regulated and 9 spots were down-regulated.48 spots were significantly altered in PD patients compared with controls when average ratio＞1.2 or＜-1.2.Of which 19 spots were considerably down-regulated in the CSF of PD patients,whereas 29 spots were considerably up-regulated.21 unique proteins(including redundancies due to proteolysis and post-translationally modified isoforms) were identified after MS and protein database interrogation.Of them 3 were albumin isoforms(fragments ?),5 were fragments of immune globin,2 were apolipoproteinA-Ⅰ(apo A-Ⅰ) isoforms,3 were unnamed proteins.13 of 21 proteins were potentially PD-related proteins. Myosin phosphatase target subunit 1(MYPT1) was identified for the first time in CSF, and apoA-Ⅰ,MYPT1,tetranectin,C4A were identified for the first time in the CSF of PD patients.The expression levels of C4,apoA-Ⅰ,IgA,tetranectin,extracellular superoxide dismutase(EC-SOD),detected by Western-blotting,correlated well with the DIGE results in PD patients and controls,and differed partially from the DIGE results in pre- and post-DBS patients.Conclusions:some of 13 proteins which belonged to potential PD related protein may serve as possible biomarkers for PD,and some of the proteins altered significantly pre- and post-DBS may be useful for better understanding of mechansism of DBS. The role of DBS for PD is probably to sustain or promote effects of micro-lesioning by the mechanism different from lesioning.