title: Homocysteine causes cerebrovascular leakage in mice.
abstract: Elevated plasma homocysteine (Hcy) is associated with cerebrovascular disease and activates matrix metalloproteinases (MMPs), which lead to vascular remodeling that could disrupt the blood-brain barrier. To determine whether Hcy administration can increase brain microvascular leakage secondary to activation of MMPs, we examined pial venules by intravital video microscopy through a craniotomy in anesthetized mice. Bovine serum albumin labeled with fluorescein isothiocyanate (BSA-FITC) was injected into a carotid artery to measure extravenular leakage. Hcy (30 microM/total blood volume) was injected 10 min after FITC-BSA injection. Four groups of mice were examined: 1) wild type (WT) given vehicle; 2) WT given Hcy (WT + Hcy); 3) MMP-9 gene knockout given Hcy (MMP-9-/- + Hcy); and 4) MMP-9-/- with topical application of histamine (10(-4) M) (MMP-9-/- + histamine). In the WT + Hcy mice, leakage of FITC-BSA from pial venules was significantly (P < 0.05) greater than in the other groups. There was no significant leakage of pial microvessels in MMP-9-/- + Hcy mice. Increased cerebrovascular leakage in the MMP-9-/- + histamine group showed that microvascular permeability could still increase by a mechanism independent of MMP-9. Treatment of cultured mouse microvascular endothelial cells with 30 microM Hcy resulted in significantly greater F-actin formation than in control cells without Hcy. Treatment with a broad-range MMP inhibitor (GM-6001; 1 microM) ameliorated Hcy-induced F-actin formation. These data suggest that Hcy increases microvascular permeability, in part, through MMP-9 activation.
authors.affiliation: Department of Physiology and Biophysics, Health Sciences Center, A-1115, University of Louisville, Louisville, Kentucky 40292, USA. dglomi01@louisville.edu
authors.forename: David
authors.initials: D
authors.lastname: Lominadze
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Roberts
authors.forename: Neetu
authors.initials: N
authors.lastname: Tyagi
authors.forename: Karni S
authors.initials: KS
authors.lastname: Moshal
authors.forename: Suresh C
authors.initials: SC
authors.lastname: Tyagi
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000503:physiopathology; D019559:Capillary Leak Syndrome / Q000139:chemically induced* / Q000503:physiopathology*; D002199:Capillary Permeability / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D006710:Homocysteine / Q000633:toxicity*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation / Q000187:drug effects / Q000503:physiopathology; D010841:Pia Mater / Q000098:blood supply* / Q000187:drug effects / Q000503:physiopathology*
chemical_list: D000199:Actins; D006710:Homocysteine; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse