title: Homocysteine enhances transmigration of rat monocytes through a brain capillary endothelial cell monolayer via ICAM-1.
abstract: Increased homocysteine (Hcy) levels contribute to a variety of cardiovascular and cerebrovascular diseases including stroke and Alzheimer's disease. Recent data has shown that elevated levels of Hcy can lead to the blood-brain barrier (BBB) dysfunction and activation. However, the mechanism for Hcy-mediated dysfunction remains unclear. The aim of this study is to characterize the effects of moderate Hcy administration in rat brain capillary endothelial cells (BCECs), which serve as a simple model to study blood-brain barrier (BBB) functions. This present study shows that addition of 20 microM Hcy for 6 days did not significantly affect BCEC survival, as measured by acridine orange staining, propidium iodide staining, and nitrite content. However, addition of 20 microM Hcy for 6 days did elevate lactate dehydrogenase (LDH) activity released into the supernatant of BCECs, as well as significantly enhance the transmigration of monocytes across the BCEC in a time-dependent manner. In addition, TNFalpha levels in BCEC were also elevated by Hcy, whereas inflammatory markers MIP3alpha and RANTES were significantly reduced. Finally, this study also shows that intercellular adhesion molecule-1 (ICAM-1) expression is significantly enhanced by 20 microM Hcy treatment compared to control conditions. These results suggest that moderate levels of homocysteine can affect proinflammatory patterns expressed by BCECs ultimately leading to BBB activation and dysfunction through enhanced monocyte transmigration and ICAM-1 expression.
authors.affiliation: Laboratory of Psychiatry and Exp. Alzheimer's Research, Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Austria.
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Hohsfield
authors.forename: Christian
authors.initials: C
authors.lastname: Humpel
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism*; D015153:Blotting, Western; D002465:Cell Movement / Q000187:drug effects*; D002470:Cell Survival; D002478:Cells, Cultured; D054418:Chemokine CCL20 / Q000378:metabolism; D018946:Chemokine CCL5 / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006710:Homocysteine / Q000494:pharmacology*; D007150:Immunohistochemistry; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: C486997:Ccl20 protein, rat; D054418:Chemokine CCL20; D018946:Chemokine CCL5; D006710:Homocysteine; D018799:Intercellular Adhesion Molecule-1