title: Regulation of the blood-brain barrier integrity by pericytes via matrix metalloproteinases mediated activation of vascular endothelial growth factor in vitro.
abstract: The blood-brain barrier consists of the cerebral microvascular endothelium, pericytes, astrocytes, and neurons. In this study, we analyzed the influence of primary porcine brain capillary pericytes on the barrier integrity of primary porcine brain capillary endothelial cells in a species-consistent in vitro coculture model. We were able to show a barrier integrity-decreasing impact of pericytes by transendothelial electrical resistance (TEER) and (14)C-sucrose permeability measurements. The morphology analysis revealed serrated cell borders and a shift of the endothelial morphology towards a cobblestone shape under the influence of pericytes. The analysis of the two major barrier integrity modulators vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs) displayed higher MMP activity and higher levels VEGF, MMP-2, and MMP-9 in the coculture, whereas VEGF levels were decreased by the MMP inhibitor GM6001, indicating a complex interplay of both. Inhibition experiments with neutralizing VEGF antibody and GM6001 increased the TEER, which proves the involvement of VEGF and MMPs in the barrier-decreasing process. Analysis of occludin yielded decreased protein content and discontinuous expression at the endothelial cell borders under the influence of pericytes. These results together reveal the potential of pericytes to regulate the endothelial barrier integrity via MMPs and VEGF.
authors.affiliation: Institute of Biochemistry, Westfälische Wilhelms-Universität Münster, Münster, Germany.
authors.forename: Gokulan
authors.initials: G
authors.lastname: Thanabalasundaram
authors.forename: Christian
authors.initials: C
authors.lastname: Pieper
authors.forename: Mira
authors.initials: M
authors.lastname: Lischper
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Galla
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001812:Blood-Brain Barrier / Q000166:cytology*; D002478:Cells, Cultured; D018920:Coculture Techniques / Q000379:methods; D004151:Dipeptides / Q000494:pharmacology; D017097:Electric Impedance; D042783:Endothelial Cells / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D062793:Occludin; D020286:Pericytes / Q000187:drug effects / Q000502:physiology*; D010750:Phosphoproteins / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism; D013552:Swine; D014316:Tritium / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein
chemical_list: D004151:Dipeptides; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D062793:Occludin; D010750:Phosphoproteins; D042461:Vascular Endothelial Growth Factor A; D062826:Zonula Occludens-1 Protein; D014316:Tritium; D013395:Sucrose; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9