Saliva α-synuclein and a high extinction coefficient protein: A novel approach in assessment biomarkers of Parkinson′s disease

Abstract

Background:The pathological hallmark of Parkinson's disease (PD) is the appearance of intracytoplasmic inclusions known as Lewy bodies in which its principal component is α-synuclein.Aim:This study aimed to determine salivary α-synuclein and the extinction coefficient of the saliva protein as biomarkers of PD.Materials and Methods:This observational study was done in Department of Pharmacology, College of Medicine in cooperation with Department of Oral Medicine, College of Dentistry at Al-Mustansiriya University in Baghdad, Iraq from September 2013 to March 2014. A total number of 20 PD patients and 20 healthy subjects were enrolled in the study. Unstimulated saliva obtained from each participant obtained for determination of salivary flow rate, saliva protein and α-synuclein using enzyme linked immune sorbent assay (ELISA) technique.Results:Total saliva protein and uncontaminated protein with nucleic acids are significantly higher in PD compared with healthy subjects. The mean extinction coefficient of that protein is 27.25 M.cm-1 which significantly (P < 0.001) less than corresponding value of healthy subjects (33.48 M.cm−1 ). Saliva α-synuclein level is significantly less in PD (65 ± 52.2 pg/ml) than healthy subjects (314.01 ± 435.9 pg/ml).Conclusions:We conclude that saliva α-synuclein serves as a biomarker for PD if its level compared with healthy subjects, and a specific protein with extinction coefficient 27.25 M.cm-1 is detected in saliva of Parkinson's patients.

Salivary microR‐153 and microR‐223 Levels as Potential Diagnostic Biomarkers of Idiopathic Parkinson's Disease

“…Saliva has advantages over other biofluids and imaging techniques because its acquisition is noninvasive, inexpensive, and requires minimal personnel training . Most groups report reduced salivary total α‐synuclein levels and higher oligomeric α‐synuclein levels in PD patients when compared with controls in addition to higher oligomeric to total α‐synuclein ratios …”

Biomarker sources for Parkinson's disease: Time to shed tears?

“…However, even a combination of both markers did not enhance the performance of this assay [42]. Significantly lower salivary levels of a-syn in saliva of PD patients were also confirmed in a recent trial [43]. Interestingly, independent work showed that nerve terminals in submandibular gland biopsies of PD patients stain positively for a-syn [44,45].…”

“…It can further be used for various DNA, microRNA, protein and metabolite analyses [42]. However, reduced salivation (hyposialorrhea) in patients with PD, that affects basal and reflex salivary secretion, can be an early problem in disease progression and complicate the analysis [43,46] (Table 1).…”

Systematic review and meta‐analysis of salivary protein concentration in Parkinson's disease

“…There has been recent interest in saliva as a fluid for biomarker discovery in Parkinson's disease (PD). Several studies, which focused on various aspects of saliva composition, have reported data on salivary protein concentration in patients with PD …”

“…Several studies, which focused on various aspects of saliva composition, have reported data on salivary protein concentration in patients with PD. [1][2][3] We conducted a systematic review and meta-analysis to combine data on protein concentration across these studies and assess the magnitude of difference between patients and controls. PubMed and EMBASE were searched for the terms "Parkinson's disease" and "saliva."…”