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Ann Rheum Dis 69:2204-2212 doi:10.1136/ard.2009.127241
  • Basic and translational research
  • Extended report

Interleukin 18 induces angiogenesis in vitro and in vivo via Src and Jnk kinases

  1. Alisa E Koch1,2
  1. 1Department of Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
  2. 2Veteran's Administration, Ann Arbor, Michigan, USA
  1. Correspondence to Dr M Asif Amin, Department of Medicine, University of Michigan Medical School, 109 Zina Pitcher, 4428 BSRB, Ann Arbor, MI 48109, USA; maamin{at}umich.edu
  1. Contributors MAA designed and executed Matrigel tube formation, mouse Matrigel plug and ST-SCID mouse chimera studies and wrote the manuscript. BJR transfected HMVECs, helped in performing the human ST-SCID mouse chimera and carried out western blotting. PJM performed chemotaxis in vitro, Matrigel tube formation and helped in performing Matrigel plug angiogenesis assays. JHR helped in performing RA ST-SCID mouse chimera and counted dye-tagged HMVECs that had migrated into a number of organs. HM performed western blotting to examine if IL-18-mediated Src and Jnk phosphorylation cross-talk with each other. CSH helped in performing the RA ST-SCID mouse chimera and cryosectioning various organs harvested from SCID mice. ENR helped in performing the human ST-SCID mouse chimera, cryosectioning and immunofluorescence microscopy. AEK participated in designing the study and in writing the manuscript.

  • Accepted 23 June 2010
  • Published Online First 2 August 2010

Abstract

Background Interleukin 18 (IL-18) is a novel mediator of angiogenesis in rheumatoid arthritis (RA).

Objective To examine the role of IL-18 in RA angiogenesis and the signalling mechanisms involved.

Methods Human dermal microvascular endothelial cell (HMVEC) chemotaxis, capillary morphogenesis assays and Matrigel plug angiogenesis assays were performed in vivo using IL-18 with or without signalling inhibitors. A novel model of angiogenesis was devised using dye-tagged HMVECs to study their homing into RA and normal (NL) synovial tissues (STs) engrafted in severe combined immunodeficient (SCID) mice.

Results IL-18-mediated angiogenesis depended on Src and Jnk, as the inhibitors of Src and Jnk blocked IL-18-induced HMVEC chemotaxis, tube formation and angiogenesis in Matrigel plugs. However, inhibitors of Janus kinase 2, p38, MEK, phosphatidylinositol-3-kinase and neutralising antibodies to vascular endothelial growth factor or stromal derived factor-1α did not alter IL-18-induced HMVEC migration. These results were confirmed with Jnk or Src sense or antisense oligodeoxynucleotides. Moreover, IL-18 induced phosphorylation of Src and Jnk in HMVECs. As proof of principle, IL-18 null mice had a significantly decreased angiogenesis compared with wild-type mice in Matrigel plug angiogenesis assays in vivo. IL-18 markedly enhanced mature HMVEC homing to human RA ST compared with NL ST in SCID mice, confirming the role of IL-18-induced angiogenesis in RA ST in vivo.

Conclusion Targeting IL-18 or its signalling intermediates may prove to be a potentially novel therapeutic strategy for angiogenesis-dependent diseases, such as RA.

Footnotes

  • Funding This study was supported by funds from the Veterans' Administration Research Service (AEK) and the Frederick G L Huetwell and William D Robinson Professorship (AEK). Additional support included funds from National Institute of Health grants AI40987 (AEK), HL58695 (AEK), AR48267 (AEK), HL094017 (BJR) and AR052482 (MAA).

  • Competing interests None

  • Provenance and peer review Not commissioned; externally peer reviewed.