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Open Access Research article

Potential biomarkers relating pathological proteins, neuroinflammatory factors and free radicals in PD patients with cognitive impairment: a cross-sectional study

Shu-yang Yu12, Li-jun Zuo1, Fang Wang1, Ze-jie Chen1, Yang Hu1, Ya-jie Wang67, Xiao-min Wang348 and Wei Zhang12345*

Author Affiliations

1 Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China

2 Department of Geriatrics, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China

3 China National Clinical Research Center for Neurological Diseases, Beijing 100050, China

4 Center of Parkinson’s Disease, Beijing Institute for Brain Disorders, Beijing 100053, China

5 Beijing Key Laboratory on Parkinson’s Disease, Beijing 100053, China

6 Core Laboratory for Clinical Medical Research, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China

7 Department of Clinical Laboratory Diagnosis, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China

8 Department of Physiology, Capital Medical University, Beijing 100069, China

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BMC Neurology 2014, 14:113  doi:10.1186/1471-2377-14-113

Published: 22 May 2014

Abstract

Background

Cognitive impairment strikingly reduces the quality of life of Parkinson’s disease (PD) patients. Studies find that pathological proteins, neuroinflammatory factors and free radicals may involve in the pathogenesis of cognitive impairment of PD, however, results are inconclusive.

Methods

We recruited 62 PD patients and 31 healthy controls. PD patients were identified with cognitive impairment, including PD with mild cognitive impairment (PD-MCI) and PD with dementia (PDD) according to the diagnostic criteria for PD-MCI and PDD issued by Movement Disorder Society Task Force. The levels of pathological proteins, including β-amyloid 1–42 (Aβ1-42),Total-tau (T-tau) and phosphorelated tau (P-tau), neuroinflammatory factors,including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interferon-γ (INF-γ) and prostaglandin E2 (PGE2), free radicals, including hydroxyl radical (·OH), hydrogen peroxide (H2O2) and nitric oxide (NO) in cerebrospinal fluid(CSF) were detected. The levels of above factors in CSF were compared among healthy controls and patients with and without cognitive impairment. Correlation analyses were performed between Montreal Cognitive Assessment (MoCA) score and the levels of above factors in CSF.

Results

T-tau level in CSF from PD-CI patients are significantly elevated comparing with those without cognitive impairment and controls (P = 0.016 and 0.004, respectively). The levels of P-tau (S396) and · OH in PD-CI patients are significantly higher than controls (P = 0.001 and 0.014, respectively). IL-6 levels in PD-CI patients are strikingly enhanced comparing with those without cognitive impairment (P = 0.005). MoCA score is negatively correlated with the levels of T-tau (r = -0.340), P-tau (S396) (r = -0.448), IL-6 (r = -0.489) and · OH (r = -0.504) in PD-CI patients.

Conclusions

Elevated levels of T-tau, P-tau (S396), IL-6 and · OH in CSF are significantly correlated with cognitive impairment in PD patients. This investigation may suggest the potential biomarkers relating pathological proteins, neuroinflammatory factors and free radicals in PD patients with cognitive impairment.

Keywords:
Parkinson’s disease; Cognitive impairment; Pathological proteins; Neuroinflammatory factors; Free radicals; Cerebrospinal fluid