High Glucose and Hypoxia-Mediated Damage to Human Brain Microvessel Endothelial Cells Induces an Altered, Pro-Inflammatory Phenotype in BV-2 Microglia In Vitro

Abstract

Diabetes is strongly linked to the development of Alzheimer’s disease (AD), though the mechanisms for this enhanced risk are unclear. Because vascular inflammation is a consistent feature of both diabetes and AD, the cerebral microcirculation could be a key target for the effects of diabetes in the brain. The goal of this study is to explore whether brain endothelial cells, injured by diabetes-related insults, glucose and hypoxia, can affect inflammatory and activation processes in microglia in vitro. Human brain microvascular endothelial cells (HBMVECs) were either treated with 5 mM glucose (control), 30 mM glucose (high glucose), exposed to hypoxia, or exposed to hypoxia plus high glucose. HBMVEC-conditioned medium was then used to treat BV-2 microglia. Alterations in microglia phenotype were assessed through measurement of nitric oxide (NO), cytokine production, microglial activation state markers, and microglial phagocytosis. HBMVECs were injured by exposure to glucose and/or hypoxia, as assessed by release of LDH, interleukin (IL)-1β, and reactive oxygen species (ROS). HBMVECs injured by glucose and hypoxia induced increases in microglial production of NO, tumor necrosis factor-α (TNFα) and matrix metalloproteinase (MMP)-9. Injured HBMVECs significantly increased microglial expression of CD11c and CLEC7A, and decreased expression of the homeostatic marker P2RY12. Finally, bead uptake by BV-2 cells, an index of phagocytic ability, was elevated by conditioned media from injured HBMVECs. The demonstration that injury to brain endothelial cells by diabetic-associated insults, glucose and hypoxia, promotes microglial inflammation supports the idea that the cerebral microcirculation is a critical locus for the deleterious effects of diabetes in the AD brain.

Neuroimmune Crosstalk Between the Peripheral and the Central Immune System in Amyotrophic Lateral Sclerosis

“…Barrier cells, including endothelial cells, pericytes, and astrocytes, secrete neuroimmune-related substances in response to immune stimulation from peripheral or central immune cells. Brain endothelial cells (BECs) can constitutively secrete interleukin 6 (IL-6), prostaglandins, and nitric oxide in response to different stimuli ( Iannucci et al, 2020 ; Charoensaensuk et al, 2021 ). As the number of pericytes is reduced in ALS ( Winkler et al, 2013 ), its inflammatory-mediated role may also contribute to ALS pathologies.…”

NRF1-mediated microglial activation triggers high-altitude cerebral edema

“…It has been reported that hypoxia-activated microglia are characterized by up-regulation of phagocytosis ( Jolivel et al., 2015 ; Bok et al., 2017 ; Iannucci et al., 2022 ). The hypoxia-treated microglia were incubated with Texas red-labelled 70000 MW dextran (Dextran-70) or 40000 MW dextran (Dextran-40) to determine the clathrin-dependent or caveolin-dependent phagocytosis, respectively.…”

“…(2015) has reported that long-term ischemia induced phagocytic phenotype of microglia ( Jolivel et al., 2015 ). Iannucci et al. (2022) showed that both high glucose and hypoxia increased microglia phagocytosis.…”

Exosomal Mir-3613-3p derived from oxygen–glucose deprivation-treated brain microvascular endothelial cell promotes microglial M1 polarization

“…Recently, the studies showed that the conditioned medium of damaged BMECs promotes microglial inflammation secretion [ 38 , 39 ]. However, the regulating the signal axis has not been established.…”