Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Victoria 3168, Australia;
J Immunol. 2014 Jan 15;192(2):589-602. doi: 10.4049/jimmunol.1202802. Epub 2013 Dec 11.
IL-32 is a multifaceted cytokine with a role in infections, autoimmune diseases, and cancer, and it exerts diverse functions, including aggravation of inflammation and inhibition of virus propagation. We previously identified IL-32 as a critical regulator of endothelial cell (EC) functions, and we now reveal that IL-32 also possesses angiogenic properties. The hyperproliferative ECs of human pulmonary arterial hypertension and glioblastoma multiforme exhibited a markedly increased abundance of IL-32, and, significantly, the cytokine colocalized with integrin αVβ3. Vascular endothelial growth factor (VEGF) receptor blockade, which resulted in EC hyperproliferation, increased IL-32 three-fold. Small interfering RNA-mediated silencing of IL-32 negated the 58% proliferation of ECs that occurred within 24 h in scrambled-transfected controls. Reduction of IL-32 neither affected apoptosis (insignificant changes in Bak-1, Bcl-2, Bcl-xL, lactate dehydrogenase, annexin V, and propidium iodide) nor VEGF or TGF-β levels, but siIL-32-transfected adult and neonatal ECs produced up to 61% less NO, IL-8, and matrix metalloproteinase-9, and up to 3-fold more activin A and endostatin. In coculture-based angiogenesis assays, IL-32γ dose-dependently increased tube formation up to 3-fold; an αVβ3 inhibitor prevented this activity and reduced IL-32γ-induced IL-8 by 85%. In matrigel plugs loaded with IL-32γ, VEGF, or vehicle and injected into live mice, we observed the anticipated VEGF-induced increase in neocapillarization (8-fold versus vehicle), but unexpectedly, IL-32γ was equally angiogenic. A second signal such as IFN-γ was required to render cells responsive to exogenous IL-32γ; importantly, this was confirmed using a completely synthetic preparation of IL-32γ. In summary, we add angiogenic properties that are mediated by integrin αVβ3 but VEGF-independent to the portfolio of IL-32, implicating a role for this versatile cytokine in pulmonary arterial hypertension and neoplastic diseases.
白细胞介素 32（IL-32）是一种多功能细胞因子，在感染、自身免疫性疾病和癌症中发挥作用，具有多种功能，包括加重炎症和抑制病毒复制。我们之前已经确定 IL-32 是内皮细胞（EC）功能的关键调节剂，现在我们揭示它还具有血管生成特性。人类肺动脉高压和多形性胶质母细胞瘤的高增殖性 EC 表现出明显增加的 IL-32 丰度，并且重要的是，细胞因子与整合素 αVβ3 共定位。血管内皮生长因子（VEGF）受体阻断，导致 EC 过度增殖，使 IL-32 增加三倍。用小干扰 RNA 介导的 IL-32 沉默使转染对照组中 24 小时内发生的 EC 增殖减少 58%。降低 IL-32 既不影响细胞凋亡（Bak-1、Bcl-2、Bcl-xL、乳酸脱氢酶、膜联蛋白 V 和碘化丙啶无显著变化），也不影响 VEGF 或 TGF-β 水平，但 siIL-32 转染的成人和新生儿 EC 产生的 NO、IL-8 和基质金属蛋白酶-9 减少多达 61%，而激活素 A 和内皮抑素增加多达 3 倍。在基于共培养的血管生成测定中，IL-32γ 剂量依赖性地增加管形成高达 3 倍；整合素 αVβ3 抑制剂可防止这种活性，并使 IL-32γ 诱导的 IL-8 减少 85%。在载有 IL-32γ、VEGF 或载体的 Matrigel 塞中，将其注射到活小鼠体内，我们观察到预期的 VEGF 诱导的新毛细血管形成增加（与载体相比增加 8 倍），但出乎意料的是，IL-32γ 同样具有血管生成作用。第二信号（如 IFN-γ）是使细胞对外源性 IL-32γ 产生反应所必需的；重要的是，这是使用完全合成的 IL-32γ 制剂来证实的。总之，我们将整合素 αVβ3 介导但不依赖于 VEGF 的血管生成特性添加到 IL-32 的作用谱中，这表明这种多功能细胞因子在肺动脉高压和肿瘤性疾病中发挥作用。
