Objective: The purpose of this paper is to characterize salivary proteome in PD comparing to healthy subjects using proteomic approach.

Background: Parkinson’s disease (PD) is progressive neurodegenerative disorders. Lewy pathology involves numerous organs. Submandibular glands are affected in about 75% of in vivo cases, with higher rates of positive findings in post-mortem histopathological studies. Salivary microbiome composition in PD patients is also different than in healthy patients. Therefore, saliva may serve as a potential source of biomarkers of Parkinson’s disease.

Method: 39 subjects (24 PD patients and 15 healthy controls) were recruited for the study. Saliva was collected in the morning hours, using RNA- Pro Sal kits. Samples were immediately frozen after collection in -80^oC. 2 ug of each saliva sample was analysed using nanoAcquity UPLC (Waters) directly coupled to a QExactive mass spectrometer (Thermo Scientific). Obtained data were pre-processed with Mascot Distiller software (Matrixscience) and protein identification was performed using Mascot Server 2.5 (Matrixscience) against the Homo sapiens protein sequences (20490 sequences) deposited in Swiss-Prot database (201903, 559,634 sequences; 201129965 residues).

Results: A total of 530 proteins and peptides were identified. We observed 10.47-fold change in concentrations of protein S100-A16 in PD group vs healthy control. We also observed higher concentrations of proteins from annexin family: annexin A2 (4.4 fold change) and annexin A8 (3.84) in PD vs control. Resistin concentration was 4.04 times higher in PD than in control. Due to variability of expression of these proteins, q-value <0.05 was not reached.

Conclusion: To our knowledge very limited data on salivary proteome of PD subjects is available. The results of our analysis indicate that salivary proteome of PD patients might be different that in healthy controls. This could be caused by oral inflammatory process, reflected by increased concentration of S100-A16 protein and resistin. The main limitations of the study are variability of expression of proteins between subjects in two groups and variations caused by external factors.

The abstract has been accepted for e-poster presentation during 6^th European Academy of Neurology Congress, Paris, France.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/salivary-proteome-in-parkinsons-disease/