title: Partial recovery of the damaged rat blood-brain barrier is mediated by adherens junction complexes, extracellular matrix remodeling and macrophage infiltration following focal astrocyte loss.
abstract: Blood-brain barrier (BBB) dysfunction is a feature of many neurodegenerative disorders. The mechanisms and interactions between astrocytes, extracellular matrix and vascular endothelial cells in regulating the mature BBB are poorly understood. We have previously shown that transitory glial fibrillary acidic protein (GFAP)-astrocyte loss, induced by the systemic administration of 3-chloropropanediol, leads to reversible disruption of tight junction complexes and BBB integrity to a range of markers. However, early restoration of BBB integrity to dextran (10-70 kDa) and fibrinogen was seen in the absence of paracellular tight junction proteins claudin-5 and occludin. In the present study we show that in the GFAP-astrocyte-lesioned rat inferior colliculus, paracellular expression of adherens junction proteins (vascular endothelial (VE)-cadherin and β-catenin) was maintained in vascular endothelial cells that lacked paracellular claudin-5 expression and which showed reversible post-translational occludin modification. Claudin-1 expression paralleled the loss and recovery of claudin-5, while claudin-3 or -12 immunoreactivity was not detected. In addition, the extracellular matrix, as visualized by laminin and fibronectin, underwent extensive reversible remodeling and perivascular CD169 macrophages become abundant throughout the lesioned inferior colliculus. At a time that GFAP-astrocytes repopulated the lesion area and tight junction proteins were returned to paracellular domains, the extracellular matrix and leukocyte profiles normalized and resembled profiles seen in control tissue. This study supports the hypothesis that a combination of paracellular adherens junctional proteins, remodeled basement membrane and the presence of perivascular leukocytes provide a temporary barrier to limit the extravasation of macromolecules and potentially neurotoxic substances into the brain parenchyma until tight junction proteins are restored to paracellular domains.
authors.affiliation: Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, 11 Hills Beach Road, Biddeford, ME 04005, USA. Electronic address: cwillis1@une.edu.
authors.forename: C L
authors.initials: CL
authors.lastname: Willis
authors.forename: R B
authors.initials: RB
authors.lastname: Camire
authors.forename: S A
authors.initials: SA
authors.lastname: Brule
authors.forename: D E
authors.initials: DE
authors.lastname: Ray
mesh_terms: D022005:Adherens Junctions / Q000502:physiology*; D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis; D001253:Astrocytes / Q000502:physiology*; D001812:Blood-Brain Barrier / Q000502:physiology*; D015153:Blotting, Western; D015820:Cadherins / Q000096:biosynthesis; D062507:Claudin-5 / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D005109:Extracellular Matrix / Q000502:physiology*; D005353:Fibronectins / Q000096:biosynthesis; D005455:Fluorescent Antibody Technique; D007245:Inferior Colliculi / Q000166:cytology; D007797:Laminin / Q000096:biosynthesis; D008264:Macrophages / Q000502:physiology*; D008297:Male; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D062793:Occludin / Q000096:biosynthesis; D051381:Rats; D011916:Rats, Inbred F344; D063267:Sialic Acid Binding Ig-like Lectin 1 / Q000096:biosynthesis; D019108:Tight Junctions / Q000502:physiology; D051176:beta Catenin / Q000096:biosynthesis; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D015820:Cadherins; D062507:Claudin-5; D005353:Fibronectins; D007797:Laminin; D062793:Occludin; D063267:Sialic Acid Binding Ig-like Lectin 1; D051176:beta Catenin; D000099152:Cadherin 5
keywords: BBB; GAPDH; GFAP; PBS; PECAM-1; TTBS; Tris–Tween-buffered saline; VE; VE-cadherin; basal lamina; blood–brain barrier; fibronectin; glial fibrillary acidic protein; glyceraldehyde 3-phosphate dehydrogenase; laminin; neurovascular unit; phosphate-buffered saline; platelet endothelial cell adhesion molecule-1; tight junctions; vascular endothelial