Propagative α-synuclein seeds as serum biomarkers for synucleinopathies
Ayami Okuzumi, Taku Hatano, Gen Matsumoto, Shuko Nojiri, Shin‐Ichi Ueno, Yoko Imamichi-Tatano, Haruka Kimura, Soichiro Kakuta, Akihide Kondo, Takeshi Fukuhara, Yuanzhe Li, Manabu Funayama, Shinji Saiki, Daisuke Taniguchi, Taiji Tsunemi, Deborah McIntyre, Jean‐Jacques Gérardy, Michel Mittelbronn, Rejko Krüger, Yasuo Uchiyama, Nobuyuki Nukina, Nobutaka Hattori
Abstract
Abnormal α-synuclein aggregation is a key pathological feature of a group of neurodegenerative diseases known as synucleinopathies, which include Parkinson's disease (PD), dementia with Lewy bodies and multiple system atrophy (MSA). The pathogenic β-sheet seed conformation of α-synuclein is found in various tissues, suggesting potential as a biomarker, but few studies have been able to reliably detect these seeds in serum samples. In this study, we developed a modified assay system, called immunoprecipitation-based real-time quaking-induced conversion (IP/RT-QuIC), which enables the detection of pathogenic α-synuclein seeds in the serum of individuals with synucleinopathies. In our internal first and second cohorts, IP/RT-QuIC showed high diagnostic performance for differentiating PD versus controls (area under the curve (AUC): 0.96 (95% confidence interval (CI) 0.95-0.99)/AUC: 0.93 (95% CI 0.84-1.00)) and MSA versus controls (AUC: 0.64 (95% CI 0.49-0.79)/AUC: 0.73 (95% CI 0.49-0.98)). IP/RT-QuIC also showed high diagnostic performance in differentiating individuals with PD (AUC: 0.86 (95% CI 0.74-0.99)) and MSA (AUC: 0.80 (95% CI 0.65-0.97)) from controls in a blinded external cohort. Notably, amplified seeds maintained disease-specific properties, allowing the differentiation of samples from individuals with PD versus MSA. In summary, here we present a novel platform that may allow the detection of individuals with synucleinopathies using serum samples.