Kesler Cristina T, Pereira Ethel R, Cui Cheryl H, Nelson Gregory M, Masuck David J, Baish James W, Padera Timothy P
*Edwin Steele Laboratory for Tumor Biology, Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts, USA; Harold B. Lee Library, Brigham Young University, Provo, Utah, USA; and Department of Biomedical Engineering, Bucknell University, Lewisburg, Pennsylvania, USA.
*Edwin Steele Laboratory for Tumor Biology, Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts, USA; Harold B. Lee Library, Brigham Young University, Provo, Utah, USA; and Department of Biomedical Engineering, Bucknell University, Lewisburg, Pennsylvania, USA
FASEB J. 2015 Sep;29(9):3668-77. doi: 10.1096/fj.14-268920. Epub 2015 May 14.
The angiopoietin (Ang) ligands are potential therapeutic targets for lymphatic related diseases, which include lymphedema and cancer. Ang-1 and Ang-2 functions are established, but those of Ang-4 are poorly understood. We used intravital fluorescence microscopy to characterize Ang-4 actions on T241 murine fibrosarcoma-associated vessels in mice. The diameters of lymphatic vessels draining Ang-4- or VEGF-C (positive control)-expressing tumors increased to 123 and 135 μm, respectively, and parental, mock-transduced (negative controls) and tumors expressing Ang-1 or Ang-2 remained at baseline (∼60 μm). Ang-4 decreased human dermal lymphatic endothelial cell (LEC) monolayer permeability by 27% while increasing human dermal blood endothelial cell (BEC) monolayer permeability by 200%. In vivo, Ang-4 stimulated a 4.5-fold increase in tumor-associated blood vessel permeability compared with control when measured using intravital quantitative multiphoton microscopy. Ang-4 activated receptor signaling in both LECs and BECs, evidenced by tyrosine kinase with Ig and endothelial growth factor homology domains-2 (TIE2) receptor, protein kinase B, and Erk1,2 phosphorylation detectable by immunoblotting. These data suggest that Ang-4 actions are mediated through cell-type-specific networks and that lymphatic vessel dilation occurs secondarily to increased vascular leakage. Ang-4 also promoted survival of LECs. Thus, blocking Ang-4 may prune the draining lymphatic vasculature and decrease interstitial fluid pressure (IFP) by reducing vascular permeability.
血管生成素（Ang）配体是淋巴相关疾病的潜在治疗靶点，这些疾病包括淋巴水肿和癌症。Ang-1和Ang-2的功能已明确，但Ang-4的功能却知之甚少。我们利用活体荧光显微镜来表征Ang-4对小鼠T241鼠纤维肉瘤相关血管的作用。引流表达Ang-4或VEGF-C（阳性对照）肿瘤的淋巴管直径分别增加到123和135μm，而亲代、空载体转导（阴性对照）以及表达Ang-1或Ang-2的肿瘤则保持在基线水平（约60μm）。Ang-4使人类真皮淋巴管内皮细胞（LEC）单层通透性降低27%，同时使人类真皮血管内皮细胞（BEC）单层通透性增加200%。在体内，当使用活体定量多光子显微镜测量时，与对照相比，Ang-4刺激肿瘤相关血管通透性增加4.5倍。Ang-4激活了LEC和BEC中的受体信号传导，通过免疫印迹可检测到具有Ig和内皮生长因子同源结构域-2（TIE2）受体、蛋白激酶B以及Erk1,2磷酸化的酪氨酸激酶来证明。这些数据表明，Ang-4的作用是通过细胞类型特异性网络介导的，并且淋巴管扩张继发于血管渗漏增加。Ang-4还促进了LEC的存活。因此，阻断Ang-4可能会通过降低血管通透性来修剪引流淋巴管并降低间质液压力（IFP）。
