title: Caveolin-1 increases proinflammatory chemoattractants and blood-retinal barrier breakdown but decreases leukocyte recruitment in inflammation.
abstract: OBJECTIVE
  Caveolin-1 (Cav-1), the signature protein of caveolae, modulates inflammatory responses, and innate immunity. However, Cav-1's role in retinal inflammation has not been rigorously tested. In this study, we examined the effect of Cav-1 ablation on the sensitivity of the retina to inflammation.
  
  
  METHODS
  Cav-1 knockout (KO) mice were challenged by intravitreal injection of lipopolysaccharide (LPS) and inflammatory cell recruitment was assessed by flow cytometry and immunohistochemistry. Leukostasis was assessed in retinal flatmounts after perfusion with FITC-labeled Concanavalin A (FITC-ConA). Chemoattractants were measured by multiplex immunoassays. Blood-retinal barrier (BRB) breakdown was assessed quantitatively by a FITC-dextran permeability assay. The ratio of extravascular to total immune cells was determined by CD45 immunohistochemistry of retinal flatmounts.
  
  
  RESULTS
  Inflammatory challenge resulted in significant blunting of proinflammatory cytokine (monocyte chemoattractant protein-1 [MCP-1/CCL2], CXCL1/KC, IL-6, and IL-1β) responses as well as reduced inflammatory BRB breakdown in Cav-1 KO retinas. Paradoxically, Cav-1 deficiency resulted in significantly increased recruitment of immune cells compared with controls as well as increased leukostasis. A similar ratio of extravascular/total leukocytes were found in Cav-1 KO and wild-type (WT) retinas suggesting that Cav-1 deficient leukocytes were as competent to extravasate as those from WT mice. We found increased levels of circulating immune cells in naïve (not challenged with LPS) Cav-1 KO mice compared with controls.
  
  
  CONCLUSIONS
  Caveolin-1 paradoxically modulates inflammatory signaling and leukocyte infiltration through distinct mechanisms. We hypothesize that Cav-1 expression may enhance inflammatory signaling while at the same time supporting the physical properties of the BRB.
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Xiaoman
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Xiaowu
authors.initials: X
authors.lastname: Gu
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Boyce
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Min
authors.initials: M
authors.lastname: Zheng
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Alaina M
authors.initials: AM
authors.lastname: Reagan
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Hui
authors.initials: H
authors.lastname: Qi
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Nawajes
authors.initials: N
authors.lastname: Mandal
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Alex W
authors.initials: AW
authors.lastname: Cohen
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Callegan
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States Department of Microbiology & Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Daniel J J
authors.initials: DJ
authors.lastname: Carr
authors.affiliation: Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Elliott
mesh_terms: D000818:Animals; D001813:Blood-Retinal Barrier / Q000502:physiology*; D015153:Blotting, Western; D051242:Caveolin 1 / Q000096:biosynthesis / Q000235:genetics*; D002630:Chemotactic Factors / Q000378:metabolism*; D004195:Disease Models, Animal; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D007113:Immunity, Innate / Q000235:genetics*; D007150:Immunohistochemistry; D007962:Leukocytes / Q000276:immunology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012313:RNA / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D014605:Uveitis / Q000235:genetics* / Q000276:immunology / Q000378:metabolism
chemical_list: C495541:Cav1 protein, mouse; D051242:Caveolin 1; D002630:Chemotactic Factors; D012313:RNA
keywords: blood–retinal barrier; caveolin; cytokines; inflammation