Blood vessel loss and inflammation cause secondary degeneration following spinal cord injury. Angiopoietin-1 through the Tie2 receptor, and other ligands through alphavbeta3 integrin, promote endothelial cell survival during developmental or tumour angiogenesis. Here, daily intravenous injections with an alphavbeta3-binding peptide named C16 or an angiopoietin-1 mimetic following a spinal cord contusion at thoracic level 9 in mice rescued epicentre blood vessels, white matter and locomotor function, and reduced detrimental inflammation. Preserved vascularity and reduced inflammation correlated with improved outcomes. C16 and angiopoietin-1 reduced leukocyte transmigration in vitro. Growth factor receptors and integrins facilitate each others' function. Therefore, angiopoietin-1 and C16 were combined and the effects were additive, resulting in almost complete functional recovery. The treatment had lasting effects when started 4 h following injury and terminated after one week. These results identify alphavbeta3 integrin and the endothelial-selective angiopoietin-1 as vascular and inflammatory regulators that can be targeted in a clinically relevant manner for neuroprotection after central nervous system trauma.

Intercellular adhesion molecule-1 (ICAM-1), 3 a cell adhesion molecule expressed in various cell types, plays a key role in mediating the inflammatory and immune responses (1). It functions as a co-stimulatory molecule during antigen presentation to T cells. ICAM-1 interaction with leukocyte integrins LFA-1 and Mac-1 promotes firm adhesion of leukocytes and their transmigration to the sites of inflammation (1-3). ICAM-1 consists of five Ig-like domains, a single transmembrane domain, and a short cytoplasmic tail. ICAM-1 is shed as soluble ICAM-1 (sICAM-1) in blood and other biological fluids. Elevated plasma levels of sICAM-1 have been reported in inflammatory, neoplastic, autoimmune, and vascular diseases (4), and sICAM-1 is utilized as a marker of inflammation and a predictor of prognosis (5, 6). Multiple signaling pathways regulate the shedding of ICAM-1 in 293 cells transfected with ICAM-1 (293 ICAM-1 ), including mitogen-activated protein kinase and phosphatidylinositol 3-kinases (7). How these signaling cascades mediate ICAM-1 release is currently unknown. Previous reports indicate that ICAM-1 is a substrate for matrix metalloprotease (MMP)-9 (8) as well as human leukocyte elastase and cathepsin G (9, 10).Ectodomain shedding is an important regulatory mechanism in the function of membrane-bound cell-surface molecules (reviewed in Refs. 11 and 12). Cytokines and their receptors, growth factors, ectoenzymes, adhesion molecules, and proteoglycans undergo shedding (13-16). The most widely studied inducer of shedding is phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C (16, 18 -20). Calcium ionophores, cytokines, growth factors, and chemotactic peptides also induce shedding (22). The majority of the shedding events are mediated by the zinc-dependent metalloproteinases of the metzincin family, which includes MMPs and proteases containing a disintegrin and metalloproteinase (ADAM) domain. Tissue inhibitors of metalloproteinases (TIMPs) regulate the activity of MMPs and some ADAMs. There are four distinct TIMPs. TIMP-1-4 inhibit a wide range of MMPs, whereas TIMP-3 is also an inhibitor of ADAM-17. ADAM-10 is inhibited by TIMP-1 and -3, whereas ADAM-8 and -9 are very poorly inhibited by, and are unlikely to be physiologically regulated by, TIMPs. To date, no ADAM has been shown to be inhibited by TIMP-2. ADAMs are type I transmembrane glycoproteins; and in addition to their proteolytic activity, they also mediate cell adhesion. Tumor necrosis factor-␣ (TNF␣)-converting enzyme (TACE) plays a central role in ectodomain shedding (16). Cell lines derived from TACE-deficient mice (TACE Ϫ/Ϫ ) verify that TACE is involved in the PMA-induced shedding of a number of structurally and functionally diverse proteins, including pro-TNF␣, L-selectin, ␤-amyloid precursor protein, transforming growth factor-␣, heparin-binding epidermal growth factor (EGF), and vascular cell adhesion molecule-1 (VCAM-1) (14, 17-21), suggesting a common shedding mechanism regulated by a protein kinase C-TACE axis. Mice lacking T...

Background: Oxidized lipids cause endothelial activation. Results: Endothelial activation by the lipid peroxidation product, 4-hydroxy-trans-2-nonenal, was associated with ER stress and was prevented by chaperones of protein folding. Conclusion: ER stress regulates endothelial activation by oxidized lipids. Significance: Vascular inflammation caused by oxidized lipids could be attenuated by decreasing ER stress.

Exposure to arsenic-contaminated water has been shown to be associated with cardiovascular disease, especially atherosclerosis. We examined the effect of arsenic exposure on atherosclerotic lesion formation, lesion composition and nature in ApoE−/− mice. Early post-natal exposure (3-week-old mice exposed to 49 ppm arsenic as NaAsO2 in drinking water for 7 weeks) increased the atherosclerotic lesion formation by 3- to 5-fold in the aortic valve and the aortic arch, without affecting plasma cholesterol. Exposure to arsenic for 13 weeks (3-week-old mice exposed to 1, 4.9 and 49 ppm arsenic as NaAsO2 in drinking water) increased the lesion formation and macrophage accumulation in a dose-dependent manner. Temporal studies showed that continuous arsenic exposure significantly exacerbated the lesion formation throughout the aortic tree at 16 and 36 weeks of age. Withdrawal of arsenic for 12 weeks after an initial exposure for 21 weeks (to 3-week-old mice) significantly decreased lesion formation as compared with mice continuously exposed to arsenic. Similarly, adult exposure to 49 ppm arsenic for 24 weeks, starting at 12 weeks of age increased lesion formation by 2- to 3.6-fold in the aortic valve, the aortic arch and the abdominal aorta. Lesions of arsenic-exposed mice displayed a 1.8-fold increase in macrophage accumulation whereas smooth muscle cell and T-lymphocyte contents were not changed. Expression of pro-inflammatory chemokine MCP-1 and cytokine IL-6 and markers of oxidative stress, protein-HNE and protein-MDA adducts were markedly increased in lesions of arsenic-exposed mice. Plasma concentrations of MCP-1, IL-6 and MDA were also significantly elevated in arsenic-exposed mice. These data suggest that arsenic exposure increases oxidative stress, inflammation and atherosclerotic lesion formation.

The migration of leukocytes through the endothelium to sites of infection or inflammation is a key process for the maintenance of physiological defense mechanisms. When this process is dis-regulated and becomes chronic, inflammatory diseases such as arteriosclerosis and arthritis manifest. The steps in leukocyte transmigration (TM) 5 are initiated though activation of the endothelial cells (ECs) by cytokines such as TNF-␣, interleukin-1, and interleukin-6. The selectins initiate the rolling and tethering of leukocytes to the endothelium. This step permits the engagement between ␤ 2 and ␤ 1 integrins with intercellular cell adhesion molecule (ICAM-1) and vascular cell adhesion molecule (VCAM-1) to allow firm adhesion and spreading of leukocytes. ECs express low levels of ICAM-1 and VCAM-1, but cytokine stimulation elevates the expression of these receptors on ECs. The migration of leukocytes through the EC barrier involves platelet endothelial cell adhesion molecule-1 and junctional adhesion molecules. Finally, proteolytic degradation of the basement membrane extracellular matrix by metalloproteinases (MPs) in particular is required to promote extravasation (reviewed in Refs. 1 and 2).Although ICAM-1, VCAM-1, and platelet endothelial cell adhesion molecule-1 play an important role in in vivo and in vitro experimental models of TM (1-4), there is little data on the mechanistic role of the individual adhesion molecules. ICAM-1 comprises of five immunoglobulin-like motifs on the extracellular surface, followed by a stem, a transmembrane domain, and a short cytoplasmic tail (5). The cytoplasmic tail contains three tyrosine residues, two of which become phosphorylated at positions 485 and 474 upon ligation to modulate ICAM-1 function (6, 7). The role of these residues in leukocyteendothelial migration has not yet been defined.Proteolysis is an important step during and after transmigration (8, 9), as degradation of the basement membrane and matrix of the media (of larger vessels) or stroma is required. The zinc-dependent MPs belonging to the metzincin family possess a highly conserved catalytic domain, yet have an enormous * This work was supported in part by National Institutes of Health Grant PO1ES011860, the Jewish Hospital Foundation, Louisville (to S. E. D.), and an American Heart Association Postdoctoral Award (to S. D. S.) from the Ohio Valley Affiliate. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.