Altered amyloid-β42 and BACE-1 proteins in plasma astrocyte-derived exosomes in hypertensive patients with cerebral microbleeds.

Background: Cerebral microbleeds (CMBs) have been found to promote Alzheimer's disease (AD) progression. Hypertension (HTN) is one of the major etiological factors for CMBs and an important risk factor for AD. However, the association between HTN-related CMBs and AD pathology remains undetermined. This study aims to identify the relationship between HTN-related CMBs and amyloid-β 42 (Aβ42) and β-site amyloid precursor protein cleaving enzyme 1 (BACE-1) levels in plasma astrocyte-derived exosomes (ADEs).

Methods: In total, 88 HTN participants including 30 with deep/infratentorial (D/I) CMBs, 30 with mixed CMBs, and 28 without CMBs were analyzed. Susceptibility-weighted imaging was performed to assess the location, presence, and number of CMBs. ELISA kits for BACE-1 and Aβ42 were employed to evaluate the levels of astrocyte-derived exosomal proteins.

Results: The results indicated that plasma ADE levels of Aβ42 were reduced in the HTN + D/I CMBs and HTN + Mixed CMBs groups relative to the HTN-CMBs group. Furthermore, the plasma ADE levels of Aβ42 were significantly associated with CMBs in patients with HTN. However, no significant differences were found in the plasma ADE levels of BACE-1 among the HTN + D/I CMBs, HTN + Mixed CMBs, and HTN-CMBs groups.

Conclusions: The study revealed that reduced plasma ADE levels of Aβ42 were significantly associated with CMBs in HTN patients. This finding suggests a potential link between HTN-related CMBs and AD-related amyloid-β pathology, offering novel insights into the mechanisms by which HTN-related CMBs promote AD progression.