title: Absence of integrin αvβ3 enhances vascular leak in mice by inhibiting endothelial cortical actin formation.
abstract: BACKGROUND
  Sepsis and acute lung injury (ALI) have devastatingly high mortality rates. Both are associated with increased vascular leak, a process regulated by complex molecular mechanisms.
  
  
  OBJECTIVE
  We hypothesized that integrin αvβ3 could be an important determinant of vascular leak and endothelial permeability in sepsis and ALI.
  
  
  METHODS
  β3 subunit knockout mice were tested for lung vascular leak after endotracheal LPS, and systemic vascular leak and mortality after intraperitoneal LPS and cecal ligation and puncture. Possible contributory effects of β3 deficiency in platelets and other hematopoietic cells were excluded by bone marrow reconstitution experiments. Endothelial cells treated with αvβ3 antibodies were evaluated for sphingosine-1 phosphate (S1P)–mediated alterations in barrier function, cytoskeletal arrangement, and integrin localization.
  
  
  RESULTS
  β3 knockout mice had increased vascular leak and pulmonary edema formation after endotracheal LPS, and increased vascular leak and mortality after intraperitoneal LPS and cecal ligation and puncture. In endothelial cells, αvβ3 antibodies inhibited barrier-enhancing and cortical actin responses to S1P. Furthermore, S1P induced translocation of αvβ3 from discrete focal adhesions to cortically distributed sites through Gi- and Rac1-mediated pathways. Cortical αvβ3 localization after S1P was decreased by αvβ3 antibodies, suggesting that ligation of the αvβ3 with its extracellular matrix ligands is required to stabilize cortical αvβ3 focal adhesions.
  
  
  CONCLUSIONS
  Our studies identify a novel mechanism by which αvβ3 mitigates increased vascular leak, a pathophysiologic function central to sepsis and ALI. These studies suggest that drugs designed to block αvβ3 may have the unexpected side effect of intensifying sepsis- and ALI-associated vascular endothelial leak.
authors: Lung Biology Center, University of California San Francisco, San Francisco, CA 94121, USA. george.su@ucsf.edu
authors: George
authors: G
authors: Su
authors: Amha
authors: A
authors: Atakilit
authors: John T
authors: JT
authors: Li
authors: Nanyan
authors: N
authors: Wu
authors: Mallar
authors: M
authors: Bhattacharya
authors: Jieling
authors: J
authors: Zhu
authors: Jennifer E
authors: JE
authors: Shieh
authors: Elizabeth
authors: E
authors: Li
authors: Robert
authors: R
authors: Chen
authors: Stephen
authors: S
authors: Sun
authors: Cynthia P
authors: CP
authors: Su
authors: Dean
authors: D
authors: Sheppard
mesh_terms: D000199:Actins / Q000378:metabolism*; D055371:Acute Lung Injury / Q000150:complications / Q000378:metabolism*; D000818:Animals; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000378:metabolism*; D005260:Female; D039302:Integrin alphaVbeta3 / Q000037:antagonists & inhibitors*; D008246:Lysophospholipids / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D011654:Pulmonary Edema / Q000150:complications / Q000378:metabolism; D018805:Sepsis / Q000150:complications / Q000378:metabolism*; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D014652:Vascular Diseases / Q000378:metabolism*
chemical_list: D000199:Actins; D039302:Integrin alphaVbeta3; D008246:Lysophospholipids; C060506:sphingosine 1-phosphate; D013110:Sphingosine