title: IL-35 Inhibits Angiogenesis through VEGF/Ang2/Tie2 Pathway in Rheumatoid Arthritis.
abstract: OBJECTIVE
  The pro-angiogenic factors vascular endothelial growth factor (VEGF) and angiopoietins (Angs) play a prominent role in synovial angiogenesis, an early and critical event in the pathogenesis of rheumatoid arthritis (RA). Interleukin (IL)-35 is an anti-inflammatory cytokine that attenuates collagen-induced arthritis, however, the mechanisms involved are not fully understood.
  
  
  METHODS
  The effects of IL-35 on endothelial cell migration, adhesion, and tube formation were examined using human umbilical vein endothelial cells (HUVEC) in vitro. The effects of IL-35 on vessel formation in vivo were examined using a murine Matrigel plugs model. MMP2/MMP9 and IL-6/IL-8 secretion were assessed by zymography and ELISA, respectively. The crosstalk between IL-35, VEGF, and Ang2 in HUVECs and RA synovial tissue explants was investigated.
  
  
  RESULTS
  IL-35 inhibited basal and VEGF-induced HUVEC migration and adhesion in vitro as well as tube formation in vitro and in vivo. VEGF increased Ang2 secretion by HUVECs and RA synovial tissue explants, and exogenous Ang2 promoted HUVEC migration, adhesion, and tube formation with similar potency to VEGF. Blocking the Ang/Tie2 pathway with a Tie2 kinase antibody inhibited the proangiogenic effects of exogenous Ang2 and VEGF in HUVECs. IL-35 inhibited basal and VEGF-induced Ang2 secretion by HUVECs and RA synovial tissue explants; it also antagonized the proangiogenic effects of exogenous Ang2 in HUVECs. Moreover, IL-35 reduced basal and VEGF/Ang2-induced MMP2/MMP9 and IL-6/IL-8 secretion.
  
  
  CONCLUSIONS
  These results suggested that IL-35 restrains RA angiogenesis and inflammation by downregulating basal and VEGF-induced Ang2 secretion as well as disrupting Ang2/Tie2 signal transduction. Our findings extend current understanding of mechanisms regulating RA angiogenesis and may support development of novel angiogenesis-targeting therapeutics for RA treatment.
authors.affiliation: Department of Rheumatology and Immunology, the First Affiliated Hospital of China Medical University, Shenyang, PR China.
authors.forename: Shenyi
authors.initials: S
authors.lastname: Jiang
authors.forename: Yuxuan
authors.initials: Y
authors.lastname: Li
authors.forename: Tiantian
authors.initials: T
authors.lastname: Lin
authors.forename: Lin
authors.initials: L
authors.lastname: Yuan
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Li
authors.forename: Suqin
authors.initials: S
authors.lastname: Wu
authors.forename: Liping
authors.initials: L
authors.lastname: Xia
authors.forename: Hui
authors.initials: H
authors.lastname: Shen
authors.forename: Jing
authors.initials: J
authors.lastname: Lu
mesh_terms: D042702:Angiopoietin-2 / Q000378:metabolism*; D000818:Animals; D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology*; D002448:Cell Adhesion / Q000187:drug effects; D002633:Chemotaxis / Q000187:drug effects; D016207:Cytokines / Q000096:biosynthesis; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism; D007378:Interleukins / Q000494:pharmacology*; D020782:Matrix Metalloproteinases / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D042787:Receptor, TIE-2 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D013583:Synovial Membrane / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism* / Q000494:pharmacology; D014945:Wound Healing / Q000187:drug effects
chemical_list: D042702:Angiopoietin-2; D016207:Cytokines; D018836:Inflammation Mediators; D007378:Interleukins; D042461:Vascular Endothelial Growth Factor A; D042787:Receptor, TIE-2; D020782:Matrix Metalloproteinases