Loss of flow induces leukocyte-mediated MMP/TIMP imbalance in dynamic in vitro blood-brain barrier model: role of pro-inflammatory cytokines.
There is substantial evidence linking blood-brain barrier (BBB) failure during cerebral ischemia to matrix metalloproteinases (MMP). BBB function may be affected by loss of shear stress under normoxia/normoglycemia, as during cardiopulmonary bypass procedures. The present study used an in vitro flow-perfused BBB model to analyze the individual contributions of flow, cytokine levels, and circulating blood leukocytes on the release/activity of MMP-9, MMP-2, and their endogenous inhibitors, the tissue inhibitors of MMPs (TIMPs), TIMP-1, and TIMP-2. The presence of circulating blood leukocytes under normoxic/normoglycemic flow cessation/reperfusion significantly increased the luminal levels of MMP-9 and activity of MMP-2, accompanied by partial reduction of TIMP-1, complete reduction of TIMP-2 and increased BBB permeability. These changes were not observed during constant flow with circulating blood leukocytes, or after normoxic/normoglycemic or hypoxic/hypoglycemic flow cessation/reperfusion without circulating blood leukocytes. The addition of anti-IL-6 or anti-TNF-alpha antibody in the lumen before reperfusion suppressed the levels of MMP-9 and activity of MMP-2, had no effect on TIMP-1, and completely restored TIMP-2 and BBB integrity. Injection of TIMP-2 in the lumen before reperfusion prevented the activation of MMP-2 and BBB permeability. These data indicate that blood leukocytes and loss of flow are major factors in the activation of MMP-2, and that cytokine-mediated differential regulation of TIMP-1 and TIMP-2 may contribute significantly to BBB failure.
Krizanac-Bengez
Ljiljana
L
Cerebrovascular Research Center, Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA. bengezl@ccf.org
Hossain
Mohammed
M
Fazio
Vince
V
Mayberg
Marc
M
Janigro
Damir
D
D000818:Animals; D001790:Blood Physiological Phenomena; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism*; D002199:Capillary Permeability / Q000187:drug effects; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D018836:Inflammation Mediators / Q000502:physiology*; D007267:Injections; D007962:Leukocytes / Q000502:physiology*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism*
D018836:Inflammation Mediators; D019715:Tissue Inhibitor of Metalloproteinase-1; D019714:Tissue Inhibitor of Metalloproteinases; D019716:Tissue Inhibitor of Metalloproteinase-2; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9