title: Substrate stiffening promotes endothelial monolayer disruption through enhanced physical forces.
abstract: A hallmark of many, sometimes life-threatening, inflammatory diseases and disorders is vascular leakage. The extent and severity of vascular leakage is broadly mediated by the integrity of the endothelial cell (EC) monolayer, which is in turn governed by three major interactions: cell-cell and cell-substrate contacts, soluble mediators, and biomechanical forces. A potentially critical but essentially uninvestigated component mediating these interactions is the stiffness of the substrate to which the endothelial monolayer is adherent. Accordingly, we investigated the extent to which substrate stiffening influences endothelial monolayer disruption and the role of cell-cell and cell-substrate contacts, soluble mediators, and physical forces in that process. Traction force microscopy showed that forces between cell and cell and between cell and substrate were greater on stiffer substrates. On stiffer substrates, these forces were substantially enhanced by a hyperpermeability stimulus (thrombin, 1 U/ml), and gaps formed between cells. On softer substrates, by contrast, these forces were increased far less by thrombin, and gaps did not form between cells. This stiffness-dependent force enhancement was associated with increased Rho kinase activity, whereas inhibition of Rho kinase attenuated baseline forces and lessened thrombin-induced inter-EC gap formation. Our findings demonstrate a central role of physical forces in EC gap formation and highlight a novel physiological mechanism. Integrity of the endothelial monolayer is governed by its physical microenvironment, which in normal circumstances is compliant but during pathology becomes stiffer.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA.
authors.forename: Ramaswamy
authors.initials: R
authors.lastname: Krishnan
authors.forename: Darinka D
authors.initials: DD
authors.lastname: Klumpers
authors.forename: Chan Y
authors.initials: CY
authors.lastname: Park
authors.forename: Kavitha
authors.initials: K
authors.lastname: Rajendran
authors.forename: Xavier
authors.initials: X
authors.lastname: Trepat
authors.forename: Jan
authors.initials: J
authors.lastname: van Bezu
authors.forename: Victor W M
authors.initials: VW
authors.lastname: van Hinsbergh
authors.forename: Christopher V
authors.initials: CV
authors.lastname: Carman
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Brain
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Fredberg
authors.forename: James P
authors.initials: JP
authors.lastname: Butler
authors.forename: Geerten P
authors.initials: GP
authors.lastname: van Nieuw Amerongen
mesh_terms: D000180:Acrylic Resins; D015703:Antigens, CD / Q000378:metabolism; D001696:Biomechanical Phenomena; D015820:Cadherins / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D003470:Culture Media / Q000737:chemistry; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008567:Membranes, Artificial; D008853:Microscopy; D013917:Thrombin / Q000494:pharmacology; D054460:rho-Associated Kinases / Q000378:metabolism; D000099166:Polyacrylamides; D000099152:Cadherin 5
chemical_list: D000180:Acrylic Resins; D015703:Antigens, CD; D015820:Cadherins; D003470:Culture Media; D008567:Membranes, Artificial; D013917:Thrombin; D054460:rho-Associated Kinases; D000099166:Polyacrylamides; D000099152:Cadherin 5