Objective: To validate the role of α-synuclein (AS) pathology in submandibular gland (SMG) as a biomarker for Parkinson disease (PD).

Background: The pathologic hallmark of PD is Lewy body pathology in the central nervous system. However, from comprehensive autopsy studies, Lewy type α-synuclein (AS) deposition was found not only in the central nervous system but also in the peripheral nervous system of multiple organs including the endocrine glands, colon, stomach and skin in PD patients. Of note is that SMG was found to express the highest percentage of AS deposition among the digestive tract in patients with PD. As SMG tissue is feasible and safe with a core needle biopsy, there have been attempts to confirm the AS pathology of the SMG in living PD patients. However, recent studies using SMG biopsy in living PD patients showed good but varying sensitivities (67~75%) and specificities (78%~100%).

Methods: We performed ultrasonography (USG) guided core needle biopsy of SMG in PD patients and procured SMG biopsy tissues or surgical excision specimens from non-PD patients as controls. Then, we compared AS deposition in the SMG tissues between the PD patients and the controls. We recruited 16 PD patients in this study. In each individual, two core needle biopsy tissues were obtained from the left submandibular gland under USG guidance. Fourteen sex and age-matched controls who did not have PD and dementia but received a core needle biopsy or surgical resection of the SMG due to SMG diseases were procured from the pathology archive. Biopsy tissues and surgical specimens were immuno-stained with serine 129 phosphorylated AS (pAS) antibody for microscopic examination. pAS deposition in neural structures such as ganglion cells and neurites was considered as positive.

Results: No serious complication occurred during and after the SMG biopsy. We found glandular parenchyma and neural structures in all biopsied SMG tissues from the patients and the controls. Nine out of 16 PD patients (56.2%) were positive for pAS staining, while none of the controls were positive (0%).

Conclusions: SMG core needle biopsy can reliably and safely obtain sufficient glandular parenchyma and neural structures to evaluate the α-synuclein pathology. AS pathology in SMG has high specificity and good sensitivity as a biomarker for PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/submandibular-gland-is-a-suitable-tissue-for-alpha-synuclein-pathology-in-parkinsons-disease/