Novel Nasal Epithelial Cell Markers of Parkinson’s Disease Identified Using Cells Treated with α-Synuclein Preformed Fibrils

• Main Authors: Hyojung Kim, Seok-Jae Kang, Young Mi Jo, Sanggyu Park, Seung Pil Yun, Yun-Song Lee, Hee-Tae Kim, Nae-Eung Lee, Yong-Sang Kim, Seok Hyun Cho, Yunjong Lee
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Journal of Clinical Medicine
• Subjects: nasal epithelial cell model; Parkinson’s disease; RPMI-2650 cells; olfactory biomarker; α-synuclein preformed fibril; olfactory dysfunction
• Online Access: https://www.mdpi.com/2077-0383/9/7/2128

Parkinson’s disease (PD) is the most common neurodegenerative movement disorder, characterized by olfactory dysfunction in the early stages. α-Synuclein pathologies in the olfactory organs are shown to spread to the brain through the nose-brain axis. We first developed a nasal epithelial PD cellular model by treating RPMI-2650 cells with α-synuclein preformed fibrils (PFF). Upon uptake of PFF, RPMI-2650 cells showed mitochondrial proteome alteration and downregulation of parkin, which has previously been identified as a nasal biomarker of PD. Functional cluster analysis of differentially expressed genes in RPMI-2650 cells revealed various pathways affected by α-synuclein pathology, including the detection of chemical stimulus involved in sensory perception, olfactory receptor activity, and sensory perception of smell. Among genes that were most affected, we validated, by real-time quantitative PCR, the downregulation of <i>MAP3K8</i>, <i>OR10A4</i>, <i>GRM2</i>, <i>OR51B6</i>, and <i>OR9A2,</i> as well as upregulation of <i>IFIT1B</i>, <i>EPN1, OR1D5, LCN, and OTOL1</i> in PFF-treated RPMI-2650 cells. Subsequent analyses of clinical samples showed a downregulation of <i>OR10A4</i> and <i>OR9A2</i> transcripts and an upregulation of <i>IFIT1B</i> in cells isolated from the nasal fluid of PD patients, as compared to those from the controls (cutoff value = 0.5689 for <i>OR9A2,</i> with 72.4% sensitivity and 75% specificity, and 1.4658 for <i>IFIT1B,</i> with 81.8% sensitivity and 77.8% specificity). Expression levels of these nasal PD markers were not altered in nasal fluid cells from SWEDD (scans without evidence of dopaminergic deficits) patients with PD-like motor symptoms. These nasal markers were significantly altered in patients of PD with hyposmia compared to the control hyposmic subjects. Our results validated the α-synuclein-treated nasal epithelial cell model to identify novel biomarkers for PD and suggest the utility of olfactory transcripts, along with olfactory dysfunction, in the diagnosis of PD.