title: The Neurorepellent Slit2 Inhibits Postadhesion Stabilization of Monocytes Tethered to Vascular Endothelial Cells.
abstract: The secreted neurorepellent Slit2, acting through its transmembrane receptor, Roundabout (Robo)-1, inhibits chemotaxis of varied cell types, including leukocytes, endothelial cells, and vascular smooth muscle cells, toward diverse attractants. The role of Slit2 in regulating the steps involved in recruitment of monocytes in vascular inflammation is not well understood. In this study, we showed that Slit2 inhibited adhesion of monocytic cells to activated human endothelial cells, as well as to immobilized ICAM-1 and VCAM-1. Microfluidic live cell imaging showed that Slit2 inhibited the ability of monocytes tethered to endothelial cells to stabilize their actin-associated anchors and to resist detachment in response to increasing shear forces. Transfection of constitutively active plasmids revealed that Slit2 inhibited postadhesion stabilization of monocytes on endothelial cells by preventing activation of Rac1. We further found that Slit2 inhibited chemotaxis of monocytes toward CXCL12 and CCL2. To determine whether Slit2 and Robo-1 modulate pathologic monocyte recruitment associated with vascular inflammation and cardiovascular disease, we tested PBMC from patients with coronary artery disease. PBMC from these patients had reduced surface levels of Robo-1 compared with healthy age- and sex-matched subjects, and Slit2 failed to inhibit chemotaxis of PBMC of affected patients, but not healthy control subjects, toward CCL2. Furthermore, administration of Slit2 to atherosclerosis-prone LDL receptor-deficient mice inhibited monocyte recruitment to nascent atherosclerotic lesions. These results demonstrate that Slit2 inhibits chemotaxis of monocytes, as well as their ability to stabilize adhesions and resist detachment forces. Slit2 may represent a powerful new tool to inhibit pathologic monocyte recruitment in vascular inflammation and atherosclerosis.
authors: Program in Cell Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario M5G 1X8, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario M5S 1A8, Canada;
authors: Ilya
authors: I
authors: Mukovozov
authors: Program in Cell Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario M5G 1X8, Canada;
authors: Yi-Wei
authors: YW
authors: Huang
authors: Division of Cardiology, Keenan Research Center for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario M5B 1T8, Canada; and.
authors: Qiuwang
authors: Q
authors: Zhang
authors: Program in Cell Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario M5G 1X8, Canada;
authors: Guang Ying
authors: GY
authors: Liu
authors: Toronto General Research Institute, University Health Network, Toronto, Ontario M5G 2C4, Canada.
authors: Allan
authors: A
authors: Siu
authors: Program in Cell Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario M5G 1X8, Canada;
authors: Yaroslav
authors: Y
authors: Sokolskyy
authors: Program in Cell Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario M5G 1X8, Canada;
authors: Sajedabanu
authors: S
authors: Patel
authors: Toronto General Research Institute, University Health Network, Toronto, Ontario M5G 2C4, Canada.
authors: Sharon J
authors: SJ
authors: Hyduk
authors: Division of Cardiology, Keenan Research Center for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario M5B 1T8, Canada; and.
authors: Michael J B
authors: MJ
authors: Kutryk
authors: Toronto General Research Institute, University Health Network, Toronto, Ontario M5G 2C4, Canada.
authors: Myron I
authors: MI
authors: Cybulsky
authors: Program in Cell Biology, The Hospital for Sick Children Research Institute, Toronto, Ontario M5G 1X8, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario M5S 1A8, Canada; lisa.robinson@sickkids.ca.
authors: Lisa A
authors: LA
authors: Robinson
mesh_terms: D000818:Animals; D050197:Atherosclerosis / Q000473:pathology; D002318:Cardiovascular Diseases / Q000276:immunology; D002448:Cell Adhesion / Q000502:physiology*; D002460:Cell Line; D018932:Chemokine CCL2; D054377:Chemokine CXCL12; D002634:Chemotaxis, Leukocyte / Q000502:physiology*; D004789:Enzyme Activation; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000276:immunology; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D009000:Monocytes / Q000276:immunology / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000378:metabolism*; D011973:Receptors, LDL / Q000235:genetics; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein
chemical_list: D018932:Chemokine CCL2; D054377:Chemokine CXCL12; D018799:Intercellular Adhesion Molecule-1; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D011971:Receptors, Immunologic; D011973:Receptors, LDL; D019010:Vascular Cell Adhesion Molecule-1; D020830:rac1 GTP-Binding Protein; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein; C111835:CCL2 protein, human; C515255:CXCL12 protein, human