Plasticity of button-like junctions in the endothelium of airway lymphatics in development and inflammation

Am J Pathol. 2012 Jun;180(6):2561-75. doi: 10.1016/j.ajpath.2012.02.019. Epub 2012 Apr 23.

Abstract

Endothelial cells of initial lymphatics have discontinuous button-like junctions (buttons), unlike continuous zipper-like junctions (zippers) of collecting lymphatics and blood vessels. Buttons are thought to act as primary valves for fluid and cell entry into lymphatics. To learn when and how buttons form during development and whether they change in disease, we examined the appearance of buttons in mouse embryos and their plasticity in sustained inflammation. We found that endothelial cells of lymph sacs at embryonic day (E)12.5 and tracheal lymphatics at E16.5 were joined by zippers, not buttons. However, zippers in initial lymphatics decreased rapidly just before birth, as buttons appeared. The proportion of buttons increased from only 6% at E17.5 and 12% at E18.5 to 35% at birth, 50% at postnatal day (P)7, 90% at P28, and 100% at P70. In inflammation, zippers replaced buttons in airway lymphatics at 14 and 28 days after Mycoplasma pulmonis infection of the respiratory tract. The change in lymphatic junctions was reversed by dexamethasone but not by inhibition of vascular endothelial growth factor receptor-3 signaling by antibody mF4-31C1. Dexamethasone also promoted button formation during early postnatal development through a direct effect involving glucocorticoid receptor phosphorylation in lymphatic endothelial cells. These findings demonstrate the plasticity of intercellular junctions in lymphatics during development and inflammation and show that button formation can be promoted by glucocorticoid receptor signaling in lymphatic endothelial cells.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / pathology
  • Animals
  • Animals, Newborn
  • Dexamethasone / pharmacology
  • Dexamethasone / therapeutic use
  • Endothelial Cells / cytology
  • Endothelial Cells / metabolism
  • Endothelium, Lymphatic / anatomy & histology*
  • Endothelium, Lymphatic / drug effects
  • Endothelium, Lymphatic / embryology
  • Endothelium, Lymphatic / growth & development
  • Female
  • Glucocorticoids / pharmacology
  • Glucocorticoids / therapeutic use
  • Intercellular Junctions / physiology
  • Intercellular Junctions / ultrastructure
  • Lung / anatomy & histology
  • Lung / embryology
  • Lung / growth & development
  • Lymphangiogenesis / drug effects
  • Mice
  • Mice, Inbred C57BL
  • Microscopy, Confocal
  • Mycoplasma Infections / drug therapy
  • Mycoplasma Infections / pathology*
  • Mycoplasma pulmonis*
  • Receptors, Glucocorticoid / metabolism
  • Tight Junctions / metabolism
  • Trachea / anatomy & histology
  • Trachea / drug effects
  • Trachea / embryology
  • Trachea / growth & development

Substances

  • Glucocorticoids
  • Receptors, Glucocorticoid
  • Dexamethasone