Optimization of the Detection Method for Phosphorylated α-Synuclein in Parkinson Disease by Skin Biopsy

Abstract

Background: Recent studies have found deposition of phosphorylated α-synuclein (p-syn) in Parkinson disease (PD) patients' skin, indicating p-syn may be a potential biomarker of PD. However, the sensitivity of the p-syn detection varied largely from 5. 3 to 100%, this influenced the clinical use of this detection method to some extent. Objective: This study aimed to optimize the skin biopsy method for detecting p-syn deposition in patients with PD. Methods: Ninety PD patients and 30 healthy controls underwent skin biopsies at 2–3 of the following sites: the distal leg, thigh, cervical region, or forearm. Skin biopsy samples were cut to 50- and 15-μm thickness sections. Deposition of p-syn were detected by using double immunofluorescence labeling of protein gene production 9.5 (PGP9.5) /p-syn. Statistical data analysis was performed using SPSS 25.0 software. Results: Deposition of p-syn were found in 75/90 PD patients but not in healthy controls ( p < 0.001). The positive deposition rate of p-syn in the single cervical site was significantly higher than that in the distal leg, thigh, and forearm site. Two samples from the cervical region had a higher p-syn positive rate compared to single cervical site (90.5 vs. 66.7%, p = 0.037). There was no significant difference between the p-syn positive rate of samples from the distal leg/cervical sites and 2 samples from cervical region (80 vs. 90.5%, p = 0.261). Next, the p-syn positive deposition rate of 2-biopsy samples including distal leg/cervical sites and double samples in the cervical site were comparable to the 3-biopsy samples. The 50-μm section had a significantly higher p-syn positive rate than the 15-μm section ( p = 0.049). Conclusions: Two biopsy sites (cervical/distal leg) or 2 samples from the cervical site were considered to be priority biopsy sites for detecting p-syn in PD patients. Thick sections may provide a higher p-syn positive rate than thin sections for skin biopsies. These findings provide an optimized p-syn detection method, indicate the valuable pathology biomarker of PD and will promote the clinical use of skin biopsy in the future.

The Value of NOTCH2NLC Gene Detection and Skin Biopsy in the Diagnosis of Neuronal Intranuclear Inclusion Disease

“…Skin samples were fixed in 4°C cold Zamboni (G2190, Solarbio) for 24–48 h. The tissues were embedded in paraffin and 4-μm serial sections were sliced. Standard pathological examinations included haematoxylin and eosin (HE) staing, anti-ubiquitin antibody (ab7780, Abcam, UK) immunostaining ( 6 ). The presence of eosinophilic or ubiquitin-positive inclusion bodies in the nuclei of sweat gland cells, fibroblasts, and fat cells was observed at 100 × magnification under light microscope (Ni-U, Nikon, Japan).…”

Neuropathology of incidental Lewy body & prodromal Parkinson’s disease

“…The diagnostic value of other biospecimens, such as those from saliva, tears, or the microbiome, is yet to be explored in patients with iRBD, and longitudinal studies are required to establish whether such biosamples will support the understanding of disease onset and progression in LBP [ 198 ]. Finally, novel methods have been developed to investigate αSyn in iRBD cases by using Real-Time Quaking-Induced Conversion assays (RT-QuIC) [ 199 – 201 ]. These assays can detect αSyn seeding activity in different LB-associated conditions with a high sensitivity and specificity [ 202 ].…”

Parkinson's disease and skin

“…For anti-pSyn, higher number of biopsy sites (≥5 versus ≤4) also correlated with higher sensitivity (0.90 versus 0.67, respectively) but not specificity (1.00 versus 1.00), whereas the number of examined sections or the specific anti-pSyn antibody did not significantly alter diagnostic accuracy. However, an analysis of pSyn positivity rate in relation to both skin section thickness and number was not performed; since the pSyn positivity rate increases with higher number [259,261] and thicker sections analyzed [266], this likely influenced the observed pSyn rate. Furthermore, in contrast to the results reported in the aforementioned meta-analysis [265], the recently published multicenter Systemic Synuclein Sampling Study (S4) found a low sensitivity of just 24.1%, with an unchanged 100% specificity, for skin biopsy in the diagnosis of PD [267].…”