Contribution of APOE genotypes to blood-brain barrier permeability in Alzheimer's disease

• Grant number: 24/19239-8
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2025
• End date: January 31, 2027
• Field of knowledge: Biological Sciences - Morphology - Cytology and Cell Biology
• Mobility Program: SPRINT - Projetos de pesquisa - Mobilidade
• Principal Investigator: Marimélia Aparecida Porcionatto
• Grantee: Marimélia Aparecida Porcionatto
• Principal researcher abroad: Anthony Robert White
• Institution abroad: QIMR Berghofer Medical Research Institute, Australia
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
• Associated researchers: Lucimara Gaziola de la Torre
• Associated research grant: 18/12605-8 - Development of brain-on-a-chip microplataforms for in vitro modeling of the central nervous system, AP.TEM

Abstract

The blood-brain barrier (BBB) is a highly selective membrane composed of endothelial cells, pericytes, and astrocytes. Its function is to regulate the exchange of substances between the brain and the bloodstream, protecting neural tissue from the entry of neurotoxic molecules, viruses, and other agents that may harm brain tissue. The BBB also regulates the exit of molecules from the brain parenchyma, including beta-amyloid peptide (Abeta), a byproduct of amyloid precursor protein (APP) cleavage. BBB dysfunction has been identified as a critical factor in the pathogenesis of sporadic Alzheimer's disease (AD), which accounts for over 95% of AD cases. The neurovascular hypothesis of sporadic AD origin suggests that BBB dysfunction contributes to the accumulation of Abeta in the brain parenchyma. It has been suggested that dysfunction in Abeta transport out of the parenchyma and the unregulated entry of Abeta from platelets into brain tissue may lead to Abeta accumulation in the brain, causing neuronal death and cognitive decline. Recently, it has been established that the apolipoprotein E (APOE) genotype is a crucial genetic risk factor in sporadic AD, with the epsilon 4 allele conferring a higher risk than the epsilon 2 or epsilon 3 alleles. APOE influences A¿ clearance and is therefore considered one of the key proteins for understanding the mechanisms of peptide accumulation in the brain. In this context, partners from the QIMR Berghofer Medical Research Institute (Australia) have generated astrocytes and endothelial cells derived from iPSCs of individuals with different APOE genotypes (E3/E3 and E4/E4) and tested them in a 2.5D in vitro BBB model. Our objective is to enhance the BBB model using a microfluidic device developed by the Brazilian team (Thematic Project 2018/12605-8), representing a dynamic three-dimensional (3D) BBB model. Among the updates to the 3D model is the use of crosslinked hydrogel (LunaGel) and Gelomics technology, simulating an environment closer to that found in vivo. Using the device, we will investigate the transport of antibodies and biomolecules across the BBB mediated by endothelial cells derived from iPSCs with different APOE genotypes. Pilot experiments conducted jointly by the two teams (Australia and Brazil) will validate the methodology and functionality of the BBB model.This SPRINT project aims to facilitate exchange between the teams to carry out preliminary experiments that will serve as a basis for developing a joint project between the two teams. This proposal will enable greater integration between the two teams to create a research project to study mechanisms of sporadic AD pathogenesis, BBB permeability to different biomolecules, and investigate the contribution of APOE genotypes to these processes. Expected outcomes include pilot experiments to assess (i) the viability and proliferation of endothelial cells and astrocytes derived from iPSCs with E3/E3 and E4/E4 genotypes in the device; (ii) BBB integrity, which will be analyzed by immunolocalization of tight junction proteins (ZO-1, Claudin-5, Occludin); (iii) the transport of biomolecules across the BBB. (AU)