# Increased Blood Plasma Levels of Methionine-Oxidized Clusterin Correlate with a Shift from Normal to Mild Cognitive Impairment and Alzheimer’s Disease Stages

## TL;DR

Higher levels of methionine-oxidized clusterin in blood plasma are linked to cognitive decline and Alzheimer's disease.

## Contribution

This study identifies methionine-oxidized clusterin in blood plasma as a potential biomarker for mild cognitive impairment and Alzheimer's disease.

## Key findings

- Methionine-oxidized clusterin levels increase in mild cognitive impairment and Alzheimer's patients compared to controls.
- The ratio of methionine-oxidized clusterin to total clusterin correlates with disease progression stages.
- The findings suggest this ratio could be used as a diagnostic marker for cognitive disorders.

## Abstract

Clusterin is a chaperon protein that is involved in many physiological processes, including binding to beta-amyloid (Aβ). Recently, we showed that in Alzheimer’s disease (AD) model mice and human postmortem brains, there are elevated levels of methionine-oxidized clusterin in the disease state versus controls. These observations prompted us to investigate the possibility that elevated methionine-oxidized levels of clusterin in human blood plasma correlate with clinical diagnosis of both mild cognitive impairment (MCI) and AD stages. To achieve this goal, we have used a combination of Elisa kits for determining the total level of clusterin and methionine-oxidized clusterin in human blood plasma, enabling the quantification of a methionine-oxidized clusterin to total clusterin ratio. This ratio was correlated with the diagnostics of three groups of patients (normal controls (NL), MCI, and AD; with n = 44 per group). Accordingly, it was determined that there was a significant increase in the relative methionine-oxidized clusterin level in the MCI and AD groups compared to the controls. In conclusion, it is suggested that increased levels of methionine-oxidized clusterin in human blood plasma may serve as a potential marker for MCI and AD diagnosis.