The axonal repellent, Slit2, inhibits directional migration of circulating neutrophils

J Leukoc Biol. 2009 Dec;86(6):1403-15. doi: 10.1189/jlb.0609391. Epub 2009 Sep 16.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Polarity / drug effects
  • Cell Polarity / immunology
  • Chemokine CXCL2 / immunology
  • Chemokine CXCL2 / pharmacology
  • Chemotaxis / drug effects
  • Chemotaxis / immunology*
  • Complement C5a / immunology
  • Complement C5a / pharmacology
  • Disease Models, Animal
  • Enzyme Activation / drug effects
  • Enzyme Activation / immunology
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / immunology
  • Humans
  • Intercellular Signaling Peptides and Proteins / immunology*
  • Interleukin-8 / immunology
  • Interleukin-8 / pharmacology
  • Mice
  • N-Formylmethionine Leucyl-Phenylalanine / immunology
  • N-Formylmethionine Leucyl-Phenylalanine / pharmacology
  • Nerve Tissue Proteins / immunology*
  • Neutrophils / immunology*
  • Peritonitis / immunology*
  • Receptors, Immunologic / immunology*
  • cdc42 GTP-Binding Protein
  • rac GTP-Binding Proteins / immunology

Substances

  • CXCL8 protein, human
  • Chemokine CXCL2
  • Cxcl2 protein, mouse
  • Intercellular Signaling Peptides and Proteins
  • Interleukin-8
  • Nerve Tissue Proteins
  • Receptors, Immunologic
  • roundabout protein
  • N-Formylmethionine Leucyl-Phenylalanine
  • Complement C5a
  • rac2 GTP-binding protein
  • cdc42 GTP-Binding Protein
  • rac GTP-Binding Proteins
  • Slit homolog 2 protein