APOE4 exacerbates post-stroke cognitive impairments and Aβ deposition in a photothrombotic mouse model.

Abstract

BACKGROUND: Apolipoprotein E4 (APOE4) is considered a potential risk factor for post-stroke cognitive impairment (PSCI); however, clinical evidence remains conflicting and the mechanisms are poorly understood. Amyloid-β (Aβ) progressively accumulates post-stroke and may drive PSCI pathogenesis. OBJECTIVES: This study aims to investigate whether APOE4 worsens cognitive outcomes after ischemic stroke, with particular emphasis on its impact on Aβ pathology. METHODS: We established a reproducible ischemic stroke model using the photothrombotic occlusion method in humanized APOE3- and APOE4-targeted replacement mice. Cognitive function was evaluated 28 days post-stroke by novel object recognition and Morris water maze tests. Subsequently, infarct volume was quantified using Nissl staining, while immunofluorescence analyses were performed to assess neuronal loss, microglial activation and Aβ deposition in the peri-infarct region and ipsilateral hippocampus. RESULTS: Compared to APOE3 stroke mice, APOE4 stroke mice exhibited exacerbated cognitive deficits, alongside larger infarcts, greater neuronal loss, and heightened neuroinflammation. Critically, APOE4 stroke mice also showed significantly increased Aβ deposition. Correlation analyses revealed that the extent of Aβ accumulation in the hippocampal CA1 region was negatively correlated with cognitive performance. Additionally, Aβ deposition was positively correlated with microglial activation and neuronal loss. CONCLUSIONS: These findings suggest that APOE4 serves as an adverse risk factor for PSCI, potentially facilitating its progression through the elevation of Aβ accumulation, thereby providing a novel target for precise intervention.