ABCA1-Labeled Exosomes in Serum Contain Higher MicroRNA-193b Levels in Alzheimer's Disease

Area of Science:

• Biochemistry
• Neuroscience
• Molecular Biology

Background:

• Alzheimer's disease (AD) diagnosis remains challenging, necessitating novel biomarkers.
• Exosomes, particularly those labeled with Apolipoprotein A1 (ABCA1), are emerging as potential carriers of disease-specific molecules.
• MicroRNAs (miRNAs) within exosomes are implicated in various biological processes and disease states.

Purpose of the Study:

• To establish a method for quantifying microRNA-193b (miR-193b) within ABCA1-labeled serum exosomes.
• To investigate the potential of ABCA1-labeled exosomal miR-193b as a diagnostic marker for Alzheimer's disease.

Main Methods:

• Immunocapture techniques were employed to isolate and quantify ABCA1-labeled exosomal miR-193b.
• Levels were assessed in cell cultures (HT-22, primary neurons, RBCs, WBCs), mouse models (APP/PS1), and human participants across cognitive decline spectrums (SCD, MCI, DAT).

Main Results:

• ABCA1-labeled exosomal miR-193b levels were significantly higher in the cerebrospinal fluid (CSF) and serum of Alzheimer's disease model mice compared to controls.
• Elevated ABCA1-labeled exosomal miR-193b levels were observed in the CSF of patients with mild cognitive impairment (MCI) and dementia of the Alzheimer type (DAT) compared to controls.
• A significant increase in serum ABCA1-labeled exosomal miR-193b was found in MCI and DAT patients, with a slight, non-significant increase in subjective cognitive decline (SCD) patients.

Conclusions:

• The study presents a validated method for capturing specific exosomes.
• Detection of ABCA1-labeled serum exosomes offers a promising avenue for the early diagnosis of Alzheimer's disease.