Noninvasive Assessment of β-Secretase Activity Through Click Chemistry-Mediated Enrichment of Neuronal Extracellular Vesicles to Detect Alzheimer's Disease.

Alzheimer's disease (AD), the most prevalent type of dementia, is characterized by a biological process that begins with the development of AD neuropathologic change (ADNPC) while individuals remain asymptomatic. A key molecular hallmark of ADNPC is the accumulation of amyloid-β plaques. β-secretase plays a critical role in the upstream pathological cleavage of amyloid precursor protein (APP), producing amyloid-β peptides that are prone to misfolding, ultimately contributing to plaque formation. Neuronal extracellular vesicles (NEVs) in the blood transport β-secretase and preserve its activity, allowing for noninvasive profiling of β-secretase activity for detecting early onset of ADNPC. In this study, a novel approach is approached for noninvasive assessment of β-secretase activity in AD patients using an NEV β-secretase activity assay. This assay identifies NEVs exhibiting colocalization of NEV markers with AD-associated β-secretase, generating a β-secretase activity profile for each patient. The NEV β-secretase activity assay represents a significant advancement in leveraging the diagnostic potential of NEVs, offering a noninvasive, quantitative method for reliably assessing β-secretase activity to detect the early onset of ADNPC.