title: Capillary defects and exaggerated inflammatory response in the airways of EphA2-deficient mice.
abstract: Both Eph receptors and ephrin ligands have been implicated in blood vessel and neuronal development. Recent studies suggested that EphA2 inhibition reduces tumor angiogenesis, but its role in blood vessel development and inflammation is unclear. We examined these issues using either airways of pathogen-free, EphA2-deficient mice at various ages or EphA2-deficient mice whose airways were inflamed by either Mycoplasma pulmonis infection or ovalbumin sensitization and challenge. EphA2-deficient mice had fewer capillaries, a greater number of endothelial sprouts, and greater capillary diameters than age-matched, wild-type control mice. Moreover, capillaries in EphA2-deficient mice had significantly less pericyte coverage, suggesting abnormal interactions between endothelial cells and pericytes. These differences were apparent in early postnatal life but decreased during progression into adulthood. In inflamed airways, significantly more angiogenesis and lymphangiogenesis, a greater number of infiltrating leukocytes, and higher expression levels of inflammatory cytokine mRNA were present in EphA2-deficient mice after M. pulmonis infection. Additionally, in allergic airway inflammation with ovalbumin sensitization and challenge, a greater number of lymphatic sprouts and infiltrating leukocytes, higher mRNA expression levels of TH2 cytokines and chemokines related to allergic airway inflammation, and enhanced airway hyper-responsiveness were present in EphA2-deficient mice. We conclude that defective pericyte coverage causes capillary defects, abundant endothelial sprouts, and thick capillary diameters in EphA2-deficient mice, indicating that these animals have exaggerated responses to airway inflammation.
authors.affiliation: Department of Anatomy, S1363, University of California, 513 Parnassus Avenue, San Francisco, CA 94143-0452, USA.
authors.forename: Tatsuma
authors.initials: T
authors.lastname: Okazaki
authors.forename: Amy
authors.initials: A
authors.lastname: Ni
authors.forename: Peter
authors.initials: P
authors.lastname: Baluk
authors.forename: Oluwasheyi A
authors.initials: OA
authors.lastname: Ayeni
authors.forename: Jennifer
authors.initials: J
authors.lastname: Kearley
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Coyle
authors.forename: Alison
authors.initials: A
authors.lastname: Humbles
authors.forename: Donald M
authors.initials: DM
authors.lastname: McDonald
mesh_terms: D000485:Allergens / Q000276:immunology; D000818:Animals; D002196:Capillaries / Q000254:growth & development / Q000473:pathology*; D016207:Cytokines / Q000096:biosynthesis; D042783:Endothelial Cells / Q000473:pathology; D007150:Immunohistochemistry; D042583:Lymphangiogenesis; D051379:Mice; D008817:Mice, Mutant Strains; D009175:Mycoplasma Infections / Q000276:immunology / Q000473:pathology; D045803:Mycoplasma pulmonis; D018919:Neovascularization, Physiologic; D010047:Ovalbumin / Q000276:immunology; D020286:Pericytes / Q000473:pathology; D011014:Pneumonia / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D036104:Receptor, EphA2 / Q000172:deficiency* / Q000235:genetics; D012130:Respiratory Hypersensitivity / Q000139:chemically induced / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018418:Th2 Cells / Q000276:immunology
chemical_list: D000485:Allergens; D016207:Cytokines; D010047:Ovalbumin; D036104:Receptor, EphA2