PROJECT SUMMARY/ABSTRACT
Alzheimer’s disease (AD) is the most common form of dementia in the elderly population and 6th leading cause
of death in the US. Despite extensive research, there are currently no treatments that slow or stop the
development of AD. With the number of AD cases expected to triple in the next 30 years, there is a pressing
need to diagnose AD early in the preclinical stage. While several peptide and protein biomarkers in cerebrospinal
fluid (CSF) have been used for AD diagnosis, an unequivocal diagnosis in the early phases of AD is still lacking.
Perhaps more importantly, the discovery and establishment of reliable biomarkers capable of monitoring
progression and degree of cognitive impairment as well as potential efficacy of therapy remains a major
challenge. Furthermore, compared to CSF, serum sample provides an appealing source for biomarker discovery
and screening due to less invasiveness and easier access. However, the correlation between CSF and blood
protein/peptide biomarkers as well as changes in the brain structure/function and cognition in AD is not well
established. In order to address these challenges and fill in existing knowledge gaps, we propose to employ a
multi-faceted approach combining a suite of mass spectrometry-based technologies enabled by innovative
multiplexed tagging strategies, improved sampling and separation strategies and clinically-available measures
to discover, identify and evaluate candidate biomarkers of AD in CSF/serum obtained from asymptomatic
cognitively-healthy middle-aged adults, older cognitively-normal adults, and patients with mild cognitive
impairment (MCI) and AD. We propose the following specific aims: Specific Aim 1 – To develop novel
enrichment strategies and complementary separation modalities for enhanced coverage of glycoproteome and
posttranslational modification crosstalk analysis in paired CSF and serum samples from subjects in control,
preclinical, MCI, AD groups, respectively. Specific Aim 2 – To enhance quantitative glycoproteomic analysis of
low-abundance species in CSF and serum samples via innovative dimethylated leucine (DiLeu) boosting and
BoxCar data-independent acquisition (DIA) strategies along with machine learning classification algorithms for
improved diagnosis of AD. Specific Aim 3 – To validate candidate AD biomarkers, in CSF and serum samples
collected from individuals with MCI and dementia, using targeted quantitative proteomics approaches enabled
by isotopic DiLeu tags and affinity-bead assisted MS immunoassay along with association with AD-related
clinical, cognitive and neuroimaging measures. This project uniquely integrates advances in MS-based
multiplexed quantitative glycoproteomics and bioinformatics tools with neuroimaging and clinical measures to
enable more comprehensive discovery and validation of CSF and serum biomarkers in AD. These biomarkers
would be invaluable in improving our understanding of AD pathogenesis, designing therapeutics for patient care
and more efficient clinical trials of disease modifying therapies. The advances in technology and new insights
will have broad impact on translational medicine.