Autocrine Effects of Brain Endothelial Cell-Produced Human Apolipoprotein E on Metabolism and Inflammation in vitro

Abstract

Reports of APOE4-associated neurovascular dysfunction during aging and in neurodegenerative disorders has led to ongoing research to identify underlying mechanisms. In this study, we focused on whether the APOE genotype of brain endothelial cells modulates their own phenotype. We utilized a modified primary mouse brain endothelial cell isolation protocol that enabled us to perform experiments without subculture. Through initial characterization we found, that compared to APOE3, APOE4 brain endothelial cells produce less apolipoprotein E (apoE) and have altered metabolic and inflammatory gene expression profiles. Further analysis revealed APOE4 brain endothelial cultures have higher preference for oxidative phosphorylation over glycolysis and, accordingly, higher markers of mitochondrial activity. Mitochondrial activity generates reactive oxygen species, and, with APOE4, there were higher mitochondrial superoxide levels, lower levels of antioxidants related to heme and glutathione and higher markers/outcomes of oxidative damage to proteins and lipids. In parallel, or resulting from reactive oxygen species, there was greater inflammation in APOE4 brain endothelial cells including higher chemokine levels and immune cell adhesion under basal conditions and after low-dose lipopolysaccharide (LPS) treatment. In addition, paracellular permeability was higher in APOE4 brain endothelial cells in basal conditions and after high-dose LPS treatment. Finally, we found that a nuclear receptor Rev-Erb agonist, SR9009, improved functional metabolic markers, lowered inflammation and modulated paracellular permeability at baseline and following LPS treatment in APOE4 brain endothelial cells. Together, our data suggest that autocrine signaling of apoE in brain endothelial cells represents a novel cellular mechanism for how APOE regulates neurovascular function.

Endothelial Cell APOE3 Regulates Neurovascular, Neuronal, and Behavioral Function

“…[17][18][19][20][21][22][23] In vitro models have also produced conflicting results on whether there are functional differences comparing APOE3 and APOE4 brain endothelial cells. 16,24,25 Therefore, at present, it is still unknown whether brain endothelial cell APOE modulates neurovascular function. Addressing this issue is crucial to advance our fundamental knowledge of APOE biology and its impact on the neurovasculature.…”

A Novel Small RNA, DsrO, in Deinococcus radiodurans Promotes Methionine Sulfoxide Reductase ( msrA ) Expression for Oxidative Stress Adaptation

“…A protein carbonyl colorimetric assay kit (Cayman Chemical, Ann Arbor, MI, USA) ( 59 ) was used to measure the protein carbonyl content of cell lysates in 96-well plates. Bacteria at the beginning of the logarithmic stage were collected for ultrasonication.…”

Endothelial Caveolin-1 and CXCL10 promote transcellular migration of autoreactive T cells across the blood-brain barrier

“…Primary mouse brain endothelial cells (mBECs) were isolated as described in detail (Marottoli et al, 2021). Briefly, cerebral cortices were isolated from 3-5 week old C57Bl/6 or Cav-1 -/- mice, minced, and digested with papain (Worthington Biochemical LK003178) and DNase (Worthington Biochemical LK003172).…”