University of Pittsburgh researchers have developed a novel, time- and cost-efficient technique to quantify amyloid-β (Aβ) biomarkers in Alzheimer’s disease (AD). A commercially available buffer was found to streamline sample preparation and improve signal-to-noise (S/N) ratios in an immunoprecipitation-mass spectrometry (IP-MS) assay. This novel assay requires less sample preparation time and reagents and could make routine non-invasive monitoring of Aβ deposits in clinical and research setting a reality.
A novel cost- and time-efficient IP-MS assay has been developed to analyze biomarkers of Aβ deposits using plasma samples. Samples can be prepared using commercially available supplement buffers and a widely available MALDI-TOF mass spectrometer improving accessibility of this assay to clinicians and researchers.
Description
Brain Aβ deposits are pathological hallmarks of AD and form part of the diagnostic criteria. Recently, anti-Aβ monoclonal antibody therapies against AD have been approved by the FDA. There is an increasing need to develop non-invasive, affordable, and efficient methods to monitor Aβ deposits in patients. Existing techniques including positron emission tomography (PET) imaging and cerebrospinal fluid (CSF) analysis are both costly and invasive, limiting routine use in clinical and research settings. Research has identified the ratio of plasma Aβ-peptides, Aβ1-42 and Aβ1-40, as biomarkers of Aβ plaque formation on the brain. This novel IP-MS assay can accurately and efficiently detect these biomarkers in plasma. The assay may result in affordable, routine quantification of Aβ brain deposits allowing clinicians to diagnose patients earlier, identify those suitable for anti-Aβ therapy, monitor the impact of AD treatments on Aβ deposits and identify patients not responsive to costly monoclonal antibody medication.
Applications
• Alzheimer’s disease
• Cerebral amyloid angiopathy (CAA)
Advantages
Plasma biomarkers have great potential use in AD diagnosis and monitoring. Previous attempts to use IP-MS have been hindered by issues including costs and the lengthy sample preparation time required to overcome interference. This novel IP-MS method is designed to overcome the limitations of earlier approaches. Using a commercially available supplement buffer the two steps of IP have been streamlined into one; the buffer enhances the S/N ratio of the biomarkers of interest, allowing for detection in small sample volumes (50 L) saving both time and reagent costs.
Invention Readiness
Using a screen of commercially available supplement buffers, N4PE CSF diluent was found to eliminate interference and increase the S/N ratio. Using plasma samples from two geographically different cohorts, the simplified IP-MS assay was validated. The novel assay demonstrated a strong S/N ratio, high dilution linearity (r² >0.99) and precision (<10%), low quantification limits (pg/mL range) and produced results comparable to existing costly IP-MS in distinguishing Aβ-PET positive from Aβ-PET negative patient brains. Further validation and optimization in larger cohorts is required.
IP Status
Patent Pending
Related Publications
Karikari, T., Chen, Y., Zeng, X., Olvera-Rojas, M., Sehrawat, A., Lafferty, T., Pascoal, T., Villemagne, V., Solis-Urra, P., Triviño-Ibañez, E., Gómez-Rí, M., Cohen, A., Ikonomovic, M., Esteban-Cornejo, I., Erickson, K., Lopez, O., & Yates, N. (2024). A streamlined, resource-efficient immunoprecipitation-mass spectrometry method for quantifying plasma amyloid-β biomarkers in Alzheimer’s disease. Springer Science and Business Media LLC. https://doi.org/10.21203/rs.3.rs-4947448/v1
Chen, Y., Zeng, X., Diaz, J. L., Sehrawat, A., Lafferty, T. K., Boslett, J. J., Klunk, W. E., Pascoal, T. A., Villemagne, V. L., Cohen, A. D., Lopez, O. I., Yates, N. A., & Karikari, T. K. (2024). Effect of blood collection tube containing protease inhibitors on the pre‐analytical stability of Alzheimer’s disease plasma biomarkers. Journal of Neurochemistry, 168(9), 2736–2750. https://doi.org/10.1111/jnc.16130
