Chemoselective Bioconjugation of Amyloidogenic Protein
Antigens to PEGylated Microspheres Enables Detection of α‑Synuclein
Autoantibodies in Human Plasma
posted on 2022-01-12, 18:07authored byPeng Ge, Mu Yang, Jacob L. Bouchard, Nicolas Dzamko, Simon J. G. Lewis, Glenda M. Halliday, Todd M. Doran
The
misfolding and subsequent aggregation of amyloidogenic proteins
is a classic pathological hallmark of neurodegenerative diseases.
Aggregates of the α-synuclein protein (αS) are implicated
in Parkinson’s disease (PD) pathogenesis, and naturally occurring
autoantibodies to these aggregates are proposed to be potential early-stage
biomarkers to facilitate the diagnosis of PD. However, upon misfolding,
αS forms a multitude of quaternary structures of varying functions
that are unstable ex vivo. Thus, when used as a capture
agent in enzyme-linked immunosorbent assays (ELISAs), significant
variance among laboratories has prevented the development of these
valuable diagnostic tests. We reasoned that those conflicting results
arise due to the high nonspecific binding and amyloid nucleation that
are typical of ELISA platforms. In this work, we describe a multiplexed,
easy-to-operate immunoassay that is generally applicable to quantify
the levels of amyloid proteins and their binding partners, named Oxaziridine-Assisted Solid-phase Immunosorbent (OASIS) assay. The assay is built on a hydrophilic poly(ethylene
glycol) scaffold that inhibits aggregate nucleation, which we show
reduces assay variance when compared to similar ELISA measurements.
To validate our OASIS assay in patient-derived samples, we measured
the levels of naturally occurring antibodies against the αS
monomer and oligomers in a cohort of donor plasma from patients diagnosed
with PD. Using OASIS assays, we observed significantly higher titers
of immunoglobulin G antibody recognizing αS oligomers in PD
patients compared to those in healthy controls, while there was no
significant difference in naturally occurring antibodies against the
αS monomer. In addition to its development into a blood test
to potentially predict or monitor PD, we anticipate that the OASIS
assay will be of high utility for studies aimed at understanding protein
misfolding, its pathology and symptomology in PD, and other neurodegenerative
diseases.