Poster Presentation Lorne Infection and Immunity 2013

IL-32 promotes angiogenesis (#145)

Claudia A Nold-Petry 1 2 , Marcel F Nold 1 2 , Jarod A Zepp 2 , Hannah Dinkel 2 , Brent E Palmer 2 , Laima Taraseviciene-Stewart 2 , Soo-Hyun Kim 3 , Charles A Dinarello 2 , Norbert F Voelkel 4
  1. Ritchie Centre, Clayton, VIC, Australia
  2. University of Colorado, Denver, USA
  3. Kunkuk University, Seoul, Korea
  4. Department of Pulmonary Medicine, Medical College of Virginia, Richmond, USA

IL-32 is a multifaceted cytokine with a role in viral and bacterial infections, autoimmune diseases, and cancer, and with diverse functions, including aggravation of inflammation and inhibition of the propagation of viruses. Moreover, IL-32 mediates the effects of IL-1β, thrombin, and platelets in endothelial cells (EC), and has been identified as a critical regulator of EC function. Here, we reveal that IL-32 possesses angiogenic properties. Immunohistochemistry demonstrated that the hyperproliferative EC in pulmonary arterial hypertension (PAH) and glioblastoma multiforme exhibited a increased IL-32 production. In an in vitro model, blockade of the receptor of vascular endothelial growth factor (VEGF) resulted in hyperproliferation of human umbilical vein EC (HUVEC) which was accompanied by a 3.4-fold increase in the abundance of IL-32. When IL-32 was silenced by siRNA in adult and fetal EC, cell proliferation of these cells was reduced compared to cells transfected with scrambled siRNA by counting and MTS-assays (change in cell number after 24 hours +58% vs -15%, respectively). This was not accompanied by an increase in apoptosis, as the levels of annexin V and LDH did not change significantly. Furthermore, HUVEC transfected with siRNA to IL-32 produced 61% less NO. To obtain in vivo evidence for the angiogenic properties of IL-32, we injected matrigel plugs loaded with IL-32γ, VEGF, or vehicle, and performed CD31- and H&E staining after 14 days. As anticipated, 25 ng/ml of VEGF increased neocapillarization 8-fold compared to vehicle, but unexpectedly the effect of 100 ng/ml IL-32γ was even stronger (8.5-fold). Unlike VEGF, IL-32γ also increased the mean vessel area (49 mm2 for control and VEGF vs 72 mm2 for IL-32γ) and lipoidosis. In summary, we add angiogenic properties to the portfolio of IL-32, implicating a role for IL-32 in PAH and neoplastic diseases.