Accelerated amyloid angiopathy and related vascular alterations in a mixed murine model of Alzheimer´s disease and type two diabetes

Abstract

Amyloid; Multiphoton microscopy; Prediabetes

Amiloide; Microscòpia multifotònica; Prediabetis

Amiloide; Microscopía multifotónica; Prediabetes

Background While aging is the main risk factor for Alzheimer´s disease (AD), emerging evidence suggests that metabolic alterations such as type 2 diabetes (T2D) are also major contributors. Indeed, several studies have described a close relationship between AD and T2D with clinical evidence showing that both diseases coexist. A hallmark pathological event in AD is amyloid-β (Aβ) deposition in the brain as either amyloid plaques or around leptomeningeal and cortical arterioles, thus constituting cerebral amyloid angiopathy (CAA). CAA is observed in 85–95% of autopsy cases with AD and it contributes to AD pathology by limiting perivascular drainage of Aβ. Methods To further explore these alterations when AD and T2D coexist, we have used in vivo multiphoton microscopy to analyze over time the Aβ deposition in the form of plaques and CAA in a relevant model of AD (APPswe/PS1dE9) combined with T2D (db/db). We have simultaneously assessed the effects of high-fat diet-induced prediabetes in AD mice. Since both plaques and CAA are implicated in oxidative-stress mediated vascular damage in the brain, as well as in the activation of matrix metalloproteinases (MMP), we have also analyzed oxidative stress by Amplex Red oxidation, MMP activity by DQ™ Gelatin, and vascular functionality. Results We found that prediabetes accelerates amyloid plaque and CAA deposition, suggesting that initial metabolic alterations may directly affect AD pathology. T2D significantly affects vascular pathology and CAA deposition, which is increased in AD-T2D mice, suggesting that T2D favors vascular accumulation of Aβ. Moreover, T2D synergistically contributes to increase CAA mediated oxidative stress and MMP activation, affecting red blood cell velocity. Conclusions Our data support the cross-talk between metabolic disease and Aβ deposition that affects vascular integrity, ultimately contributing to AD pathology and related functional changes in the brain microvasculature.

University of Cadiz Predoctoral Fellowship (CHB). This study is part of the current project (RECOGNISED; Clinical Trials gov registration no. NCT04281186) funded by the European Commission (H2020 programme-GA 847749) focusing on common mechanisms in the pathogenesis of diabetic retinopathy, brain pathology and cognitive impairment, with special interest in the neurovascular unit, in the T2D population. Agencia Estatal de Investigacion. Ministerio de Ciencia e Innovacion. Programa Estatal de Generacion de Conocimiento y Fortalecimiento Cientifico y Tecnologico del Sistema de I + D + i y del Programa Estatal de I + D + i Orientada a los Retos de la Sociedad, del Plan Estatal de Investigacion Cientifica y Tecnica y de Innovacion (PID2020-115499RB-I00/AEI/10.130 39/501100011033). Programa Estatal de I + D + I orientada a los Retos de la Sociedad (BFU 2016-75038-R), financed by the Agencia Estatal de Investigacion (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER), Ministerio de Economia y Competitividad. Proyectos de I + D + i, en regimen de concurrencia competitiva, destinadas a las universidades y entidades publicas de investigacion calificadas como agentes del Sistema Andaluz del Conocimiento, en el ambito del Plan Andaluz de Investigacion, Desarrollo e Innovación (PAIDI 2020). Andalucia se mueve con Europa (P20-00928).