title: The axonal repellent, Slit2, inhibits directional migration of circulating neutrophils.
abstract: In inflammatory diseases, circulating neutrophils are recruited to sites of injury. Attractant signals are provided by many different chemotactic molecules, such that blockade of one may not prevent neutrophil recruitment effectively. The Slit family of secreted proteins and their transmembrane receptor, Robo, repel axonal migration during CNS development. Emerging evidence shows that by inhibiting the activation of Rho-family GTPases, Slit2/Robo also inhibit migration of other cell types toward a variety of chemotactic factors in vitro and in vivo. The role of Slit2 in inflammation, however, has been largely unexplored. We isolated primary neutrophils from human peripheral blood and mouse bone marrow and detected Robo-1 expression. Using video-microscopic live cell tracking, we found that Slit2 selectively impaired directional migration but not random movement of neutrophils toward fMLP. Slit2 also inhibited neutrophil migration toward other chemoattractants, namely C5a and IL-8. Slit2 inhibited neutrophil chemotaxis by preventing chemoattractant-induced actin barbed end formation and cell polarization. Slit2 mediated these effects by suppressing inducible activation of Cdc42 and Rac2 but did not impair activation of other major kinase pathways involved in neutrophil migration. We further tested the effects of Slit2 in vivo using mouse models of peritoneal inflammation induced by sodium periodate, C5a, and MIP-2. In all instances, Slit2 reduced neutrophil recruitment effectively (P<0.01). Collectively, these data demonstrate that Slit2 potently inhibits chemotaxis but not random motion of circulating neutrophils and point to Slit2 as a potential new therapeutic for preventing localized inflammation.
authors.affiliation: The Hospital for Sick Children Research Institute, Toronto, Canada.
authors.forename: Soumitra
authors.initials: S
authors.lastname: Tole
authors.forename: Ilya M
authors.initials: IM
authors.lastname: Mukovozov
authors.forename: Yi-Wei
authors.initials: YW
authors.lastname: Huang
authors.forename: Marco A O
authors.initials: MA
authors.lastname: Magalhaes
authors.forename: Ming
authors.initials: M
authors.lastname: Yan
authors.forename: Min Rui
authors.initials: MR
authors.lastname: Crow
authors.forename: Guang Ying
authors.initials: GY
authors.lastname: Liu
authors.forename: Chun Xiang
authors.initials: CX
authors.lastname: Sun
authors.forename: Yves
authors.initials: Y
authors.lastname: Durocher
authors.forename: Michael
authors.initials: M
authors.lastname: Glogauer
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Robinson
mesh_terms: D000818:Animals; D016764:Cell Polarity / Q000187:drug effects / Q000276:immunology; D054426:Chemokine CXCL2 / Q000276:immunology / Q000494:pharmacology; D002633:Chemotaxis / Q000187:drug effects / Q000276:immunology*; D015936:Complement C5a / Q000276:immunology / Q000494:pharmacology; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000276:immunology*; D016209:Interleukin-8 / Q000276:immunology / Q000494:pharmacology; D051379:Mice; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000276:immunology / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology*; D010538:Peritonitis / Q000276:immunology*; D011971:Receptors, Immunologic / Q000276:immunology*; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins / Q000276:immunology; D000097766:RAC2 GTP-Binding Protein; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein
chemical_list: D054426:Chemokine CXCL2; D015936:Complement C5a; D036341:Intercellular Signaling Peptides and Proteins; D016209:Interleukin-8; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009419:Nerve Tissue Proteins; D011971:Receptors, Immunologic; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D000097766:RAC2 GTP-Binding Protein; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein; C508606:CXCL8 protein, human; C404915:Cxcl2 protein, mouse