Proteasome Activity in the Plasma as a Novel Biomarker in Mild Cognitive Impairment with Chronic Tinnitus.

Proteasome Activity in the Plasma as a Novel Biomarker in Mild Cognitive Impairment with Chronic Tinnitus.:

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Proteasome Activity in the Plasma as a Novel Biomarker in Mild Cognitive Impairment with Chronic Tinnitus.
J Alzheimers Dis. 2020 Sep 11;:
Authors: Yun Y, Lee SY, Hoon Choi W, Park JC, Han Lee D, Kim YK, Hoon Lee J, Lee JY, Jae Lee M, Ho Kim Y
Abstract
BACKGROUND: Although the existence of proteasomes in human blood, termed circulating proteasomes (c-proteasomes), has been reported previously, their origin and pathophysiological functions remain largely unknown.
OBJECTIVE: Given that c-proteasome activity was significantly reduced in Alzheimer's disease model mice and relatively high frequency of mild cognitive impairment (MCI) is accompanied by chronic tinnitus in aged patients, we examined whether c-proteasome activity in human plasma was associated with cognitive function in patients with chronic tinnitus.
METHODS: c-Proteasome activity in the plasma of tinnitus patients (N = 56) was measured with fluorogenic reporter substrate, suc-LLVY-AMC. To assess MCI, the Montreal Cognitive Assessment was conducted with a cut-off score of 22/23. All patients underwent audiological and psychoacoustic analyses. Levels of c-proteasomes, Aβ42, and Aβ40 were measured using ELISA, and their association with c-proteasome activity was evaluated.
RESULTS: The activity of circulating proteasomes was significantly lower in patients with chronic tinnitus and MCI (p = 0.042), whereas activities of other plasma enzymes showed little correlation. In addition, c-proteasome activity was negatively associated with the level of plasma Aβ and was directly dependent on its own concentration in the plasma of patients with chronic tinnitus.
CONCLUSION: Our current work provides a new perspective for understanding the potential relationship between circulating proteasomes in the plasma and cognitive dysfunction, suggesting a novel, non-invasive biomarker in the context of MCI diagnosis.

PMID: 32955464 [PubMed - as supplied by publisher]