Neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD) affect millions of people worldwide—a number that is increasing with an aging global population and growing life expectancies.1,2 Clinical symptoms typically only manifest decades after the onset of pathological mechanisms. As such, not only is diagnosis based on external presentation difficult, but it also often occurs only after irreversible damage has been done.1 Consequently, most modern treatment strategies focus on slowing disease progression and managing symptoms.2
The Importance of Biomarkers
Neurodegenerative disease research has largely prioritized early detection efforts, seeking to both better understand asymptomatic disease progression and identify new possibilities for therapeutic intervention. Identifying and establishing specific biomarkers have proven key to these initiatives. Classically, cerebrospinal fluid (CSF) biomarker analysis has been formative to the characterization of pathological processes such as amyloid beta (Aβ) accumulation, tau phosphorylation, and neuronal injury.1 However, examining CSF biomarkers in patients is laborious and invasive, creating a gap between laboratory discovery and clinical implementation.1 Improved detection technologies enabling blood-based biomarker detection and analysis strategies are not only positioned to bridge this gap but can also accelerate research efforts into neurodegenerative disease pathogenesis and progression.1,3
Key Biomarkers for Neurodegenerative Disease Research
Some of the most well-studied and established proteins involved in neurodegenerative disease pathology are alpha synuclein (αSyn), amyloid beta (Aβ), and tau. Researchers generally focus on the presence or absence of specific variants, post-translational modifications (PTMs), or ratios of these proteins as biomarkers of disease onset and progression.
Alpha synuclein (αSyn) is a small protein primarily expressed by neurons that normally regulates synaptic neurotransmitter release and reuptake. Under physiological conditions, αSyn is primarily a soluble, intrinsically disordered protein that can adopt membrane-associated α-helical conformations.
Some studies suggest that α-synuclein may also exist as tetrameric or other multimeric assemblies in cells, and disruption of these assemblies has been associated with increased aggregation and neurotoxicity. Misfolding and oligomerization of α-synuclein are widely considered key contributors to Parkinson's disease pathogenesis.
To that end, oligomeric αSyn can serve as an early detection biomarker for PD, as oligomerization often precedes neuronal death. Likewise, the oligomer-to-total αSyn ratio has emerged as a promising biomarker for distinguishing PD pathology and is under active investigation for diagnostic applications.4
Amyloid beta (Aβ) is the main component of the extracellular plaques that form and spread in the brains of AD patients, leading to synaptic dysfunction, brain atrophy, and cognitive decline.5,6 Although extensive research has been conducted regarding Aβ generation, clearance, and activity, the precise mechanisms that drive pathological Aβ accumulation remain unclear.6,7
Multiple amyloid beta (Aβ) isoforms are produced from APP processing, with Aβ40 and Aβ42 being the two predominant forms under physiological conditions. Aβ42 is particularly prone to aggregation and is strongly associated with the formation of toxic oligomers and amyloid plaques. Thus, Aβ42 levels, as well as the Aβ42/Aβ40 ratio, are commonly used as biomarkers for existing brain Aβ deposition and likelihood of aggregation.8-10
Amyloid beta accumulation during AD pathogenesis and progression is accompanied by hyperphosphorylation of tau, which prevents its homeostatic function and facilitates the formation of neurotoxic intracellular tau tangles.6 The causes behind tau hyperphosphorylation remain unclear, and researchers continue to investigate the multiple kinase and phosphatase pathways involved in tau regulation.7 Tau contains over eighty potential phosphorylation sites. Among the numerous phosphorylation sites identified on tau, p-tau181, p-tau217, and p-tau231 have emerged as particularly valuable biomarkers for Alzheimer's disease research and diagnostic development.11-12
Furthermore, Aβ and tau pathologies appear to exert synergistically deleterious effects on brain function and overall health. The interplay between these two key drivers of AD warrants further investigation and may represent a promising target for the development of novel treatment approaches.7
Using ELISA for Biomarker Detection
The enzyme-linked immunosorbent assay (ELISA) is a cornerstone technology for measuring neurodegenerative disease biomarkers in research settings and has also contributed to the development and validation of several clinical biomarker assays. ELISAs are commonly used to study neurodegenerative disease biomarkers such as oligomerized and phosphorylated αSyn, Aβ isoforms and variant ratios, and phosphorylated tau in laboratory settings.4,13-15
When studying neurodegenerative disease biomarkers using ELISA, researchers should ensure that assays are designed with the specific properties of their targets in mind. Tau, Aβ, and αSyn can exist in multiple molecular forms, some of which are associated with neurodegenerative disease pathology, whereas others are necessary for normal physiological function. Therefore, ELISAs targeting biomarkers for neurodegeneration must be designed to distinguish and accurately detect the specific molecular forms or modifications relevant to the biological question being investigated.
Continuous Refinement of the ELISA
While singleplex ELISAs remain widely used for protein quantification, researchers are increasingly complementing them with multiplex immunoassays and mass spectrometry-based approaches that can simultaneously measure multiple neurodegeneration-related biomarkers from limited sample volumes.16,17
ELISAs remain a robust, cost-effective, accessible, and highly specific method for biomarker detection in preclinical applications8,16 and can serve as an important bridge between high-throughput multiplex screening and costly ultrasensitive assays by independently validating candidate biomarkers identified through multiplex approaches before committing to more resource-intensive analyses.
To that end, ELISAs, as with any other laboratory technique, are constantly undergoing improvement and refinement. Scientists are seeking strategies and technologies that offer greater sensitivity, improved specificity, and faster turnaround times.18
StressMarq Biosciences offers innovative tools for preclinical neurodegenerative disease research, including an Alpha Synuclein Oligomer ELISA Kit, which has shown higher affinity for neurotoxic oligomers than for monomeric alpha synuclein. As ELISA-based biomarker detection continues to evolve, StressMarq is actively developing and refining tools designed to support sensitive and specific detection of neurodegenerative proteins.
A tau p217 ELISA kit and an ELISA kit to detect antibodies to alpha synuclein are currently in development, which will further expand StressMarq’s ELISA portfolio, leveraging the company’s established expertise in producing highly validated, biologically relevant fibrillar, oligomeric, monomeric protein constructs, plus kits and antibodies for biomarker detection and characterization. These products are developed exclusively for basic, translational, and pre-clinical research applications.
To explore StressMarq’s innovative tools for neurodegenerative disease research,* and to stay informed about the future release of ELISA kits for neurodegeneration studies, visit https://www.stressmarq.com/research/neuroscience/neurodegeneration/ and subscribe to the StressMarq e-newsletter.
* StressMarq Biosciences’ products are intended for Research Use Only (RUO).
References
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