title: Transcellular Pathways in Lymphatic Endothelial Cells Regulate Changes in Solute Transport by Fluid Stress.
abstract: BACKGROUND
  The transport of interstitial fluid and solutes into lymphatic vessels is important for maintaining interstitial homeostasis and delivering antigens and soluble factors to the lymph node for immune surveillance. Transendothelial transport across lymphatic endothelial cells (LECs) is commonly considered to occur paracellularly, or between cell-cell junctions, and driven by local pressure and concentration gradients. However, emerging evidence suggests that LECs also play active roles in regulating interstitial solute balance and can scavenge and store antigens, raising the possibility that vesicular or transcellular pathways may be important in lymphatic solute transport.
  
  
  OBJECTIVE
  The aim of this study was to determine the relative importance of transcellular (vesicular) versus paracellular transport pathways by LECs and how mechanical stress (ie, fluid flow conditioning) alters either pathway.
  
  
  RESULTS
  We demonstrate that transcellular transport mechanisms substantially contribute to lymphatic solute transport and that solute uptake occurs in both caveolae- and clathrin-coated vesicles. In vivo, intracelluar uptake of fluorescently labeled albumin after intradermal injection by LECs was similar to that of dermal dendritic cells. In vitro, we developed a method to differentially quantify intracellular solute uptake versus transendothelial transport by LECs. LECs preconditioned to 1 µm/s transmural flow demonstrated increased uptake and basal-to-apical solute transport, which could be substantially reversed by blocking dynamin-dependent vesicle formation.
  
  
  CONCLUSIONS
  These findings reveal the importance of intracellular transport in steady-state lymph formation and suggest that LECs use transcellular mechanisms in parallel to the well-described paracellular route to modulate solute transport from the interstitium according to biomechanical cues.
authors.affiliation: From the Institute of Bioengineering and Swiss Institute for Experimental Cancer Research (ISREC), École Polytechnique Fédérale de Lausanne (V.T., E.G., W.W.K., M.P., M.A.S.); and Institute for Molecular Engineering, The University of Chicago, IL (W.W.K., M.A.S.).
authors.forename: Valentina
authors.initials: V
authors.lastname: Triacca
authors.affiliation: From the Institute of Bioengineering and Swiss Institute for Experimental Cancer Research (ISREC), École Polytechnique Fédérale de Lausanne (V.T., E.G., W.W.K., M.P., M.A.S.); and Institute for Molecular Engineering, The University of Chicago, IL (W.W.K., M.A.S.).
authors.forename: Esra
authors.initials: E
authors.lastname: Güç
authors.affiliation: From the Institute of Bioengineering and Swiss Institute for Experimental Cancer Research (ISREC), École Polytechnique Fédérale de Lausanne (V.T., E.G., W.W.K., M.P., M.A.S.); and Institute for Molecular Engineering, The University of Chicago, IL (W.W.K., M.A.S.).
authors.forename: Witold W
authors.initials: WW
authors.lastname: Kilarski
authors.affiliation: From the Institute of Bioengineering and Swiss Institute for Experimental Cancer Research (ISREC), École Polytechnique Fédérale de Lausanne (V.T., E.G., W.W.K., M.P., M.A.S.); and Institute for Molecular Engineering, The University of Chicago, IL (W.W.K., M.A.S.).
authors.forename: Marco
authors.initials: M
authors.lastname: Pisano
authors.affiliation: From the Institute of Bioengineering and Swiss Institute for Experimental Cancer Research (ISREC), École Polytechnique Fédérale de Lausanne (V.T., E.G., W.W.K., M.P., M.A.S.); and Institute for Molecular Engineering, The University of Chicago, IL (W.W.K., M.A.S.). melodyswartz@uchicago.edu.
authors.forename: Melody A
authors.initials: MA
authors.lastname: Swartz
mesh_terms: D000818:Animals; D021941:Caveolae / Q000378:metabolism; D022163:Clathrin-Coated Vesicles / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D004729:Endothelium, Lymphatic / Q000378:metabolism* / Q000648:ultrastructure; D045604:Extracellular Fluid / Q000378:metabolism*; D005260:Female; D018495:Fluid Shifts; D006801:Humans; D007271:Injections, Intradermal; D008297:Male; D008807:Mice, Inbred BALB C; D010539:Permeability; D012709:Serum Albumin / Q000008:administration & dosage / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000008:administration & dosage / Q000378:metabolism*; D000075462:Serum Albumin, Human; D012867:Skin / Q000378:metabolism* / Q000648:ultrastructure; D013314:Stress, Mechanical; D013997:Time Factors; D057900:Transcytosis
chemical_list: C422455:ALB protein, human; D012709:Serum Albumin; D012710:Serum Albumin, Bovine; D000075462:Serum Albumin, Human
keywords: caveolin-1; clathrin; dextran; endothelial cell; lymphatic vessel