title: Angiopoietin-4 increases permeability of blood vessels and promotes lymphatic dilation.
abstract: 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.
authors.affiliation: *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.
authors.forename: Cristina T
authors.initials: CT
authors.lastname: Kesler
authors.affiliation: *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.
authors.forename: Ethel R
authors.initials: ER
authors.lastname: Pereira
authors.affiliation: *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.
authors.forename: Cheryl H
authors.initials: CH
authors.lastname: Cui
authors.affiliation: *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.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Nelson
authors.affiliation: *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.
authors.forename: David J
authors.initials: DJ
authors.lastname: Masuck
authors.affiliation: *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.
authors.forename: James W
authors.initials: JW
authors.lastname: Baish
authors.affiliation: *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 tpadera@steele.mgh.harvard.edu.
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Padera
mesh_terms: D042682:Angiopoietins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002199:Capillary Permeability; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology; D005354:Fibrosarcoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006801:Humans; D042601:Lymphatic Vessels / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D009374:Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D042582:Vascular Endothelial Growth Factor C / Q000235:genetics / Q000378:metabolism
chemical_list: D042682:Angiopoietins; C467486:VEGFC protein, human; D042582:Vascular Endothelial Growth Factor C; C118117:angiopoietin 4; C467483:vascular endothelial growth factor C, mouse; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3
keywords: 2-photon microscopy; TIE2; endothelial; lymphangiography