title: Regulation of lymphangiogenesis in the diaphragm by macrophages and VEGFR-3 signaling.
abstract: Lymphatic vessels play important roles in fluid drainage and in immune responses, as well as in pathological processes including cancer progression and inflammation. While the molecular regulation of the earliest lymphatic vessel differentiation and development has been investigated in much detail, less is known about the control and timing of lymphatic vessel maturation in different organs, which often occurs postnatally. We investigated the time course of lymphatic vessel development on the pleural side of the diaphragmatic muscle in mice, the so-called submesothelial initial diaphragmatic lymphatic plexus. We found that this lymphatic network develops largely after birth and that it can serve as a reliable and easily quantifiable model to study physiological lymphangiogenesis in vivo. Lymphangiogenic growth in this tissue was highly dependent on vascular endothelial growth factor receptor (VEGFR)-3 signaling, whereas VEGFR-1 and -2 signaling was dispensable. During diaphragm development, macrophages appeared first in a linearly arranged pattern, followed by ingrowth of lymphatic vessels along these patterned lines. Surprisingly, ablation of macrophages in colony-stimulating factor-1 receptor (Csf1r)-deficient mice and by treatment with a CSF-1R-blocking antibody did not inhibit the general lymphatic vessel development in the diaphragm but specifically promoted branch formation of lymphatic sprouts. In agreement with these findings, incubation of cultured lymphatic endothelial cells with conditioned medium from P7 diaphragmatic macrophages significantly reduced LEC sprouting. These results indicate that the postnatal diaphragm provides a suitable model for studies of physiological lymphangiogenic growth and maturation, and for the identification of modulators of lymphatic vessel growth.
authors.affiliation: Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Vladimir-Prelog-Weg 3, HCI H303, 8093, Zurich, Switzerland.
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Ochsenbein
authors.affiliation: Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Vladimir-Prelog-Weg 3, HCI H303, 8093, Zurich, Switzerland.
authors.forename: Sinem
authors.initials: S
authors.lastname: Karaman
authors.affiliation: Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Vladimir-Prelog-Weg 3, HCI H303, 8093, Zurich, Switzerland.
authors.forename: Steven T
authors.initials: ST
authors.lastname: Proulx
authors.affiliation: Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Vladimir-Prelog-Weg 3, HCI H303, 8093, Zurich, Switzerland.
authors.forename: Rhea
authors.initials: R
authors.lastname: Goldmann
authors.affiliation: Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Vladimir-Prelog-Weg 3, HCI H303, 8093, Zurich, Switzerland.
authors.forename: Jyothi
authors.initials: J
authors.lastname: Chittazhathu
authors.affiliation: Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Vladimir-Prelog-Weg 3, HCI H303, 8093, Zurich, Switzerland.
authors.forename: Athanasia
authors.initials: A
authors.lastname: Dasargyri
authors.affiliation: Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Vladimir-Prelog-Weg 3, HCI H303, 8093, Zurich, Switzerland.
authors.forename: Chloé
authors.initials: C
authors.lastname: Chong
authors.affiliation: Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Vladimir-Prelog-Weg 3, HCI H303, 8093, Zurich, Switzerland.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Leroux
authors.affiliation: Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Yeshiva University, New York, NY, 10461, USA.
authors.forename: E Richard
authors.initials: ER
authors.lastname: Stanley
authors.affiliation: Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, ETH Zurich, Vladimir-Prelog-Weg 3, HCI H303, 8093, Zurich, Switzerland. michael.detmar@pharma.ethz.ch.
authors.forename: Michael
authors.initials: M
authors.lastname: Detmar
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D003964:Diaphragm / Q000166:cytology / Q000254:growth & development* / Q000502:physiology; D005260:Female; D042583:Lymphangiogenesis / Q000502:physiology*; D042601:Lymphatic Vessels / Q000166:cytology / Q000502:physiology; D008264:Macrophages / Q000166:cytology / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics; D015398:Signal Transduction; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: C000604004:Csf1r protein, mouse; D017077:Culture Media, Conditioned; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D040321:Vascular Endothelial Growth Factor Receptor-3
keywords: Development; Lymphatic vessels; Macrophages; VEGFR-3