title: Airway exposure to staphylococcal enterotoxin A potentiates allergen-induced bone marrow eosinophilia and trafficking to peripheral blood and airways.
abstract: Bone marrow (BM) eosinopoiesis is a common feature during allergen exposure in atopic individuals. Airway exposure to staphylococcal superantigens aggravates allergic airway disease and increases the output of BM eosinophils. However, the exact mechanisms regulating eosinophil mobilization and trafficking to the peripheral circulation and airways remain to be elucidated. Therefore, this study aimed to investigate the mechanisms determining the BM eosinopoiesis in allergic mice under exposure to staphylococcal enterotoxin A (SEA). Ovalbumin (OVA)-sensitized male BALB/C mice were intranasally exposed to SEA (1 μg), and at 4, 12, 24, and 48 h later animals were challenged with OVA (10 μg, twice a day). Measurement of IL-5, eotaxin, and granulocyte-macrophage colony-stimulating factor (GM-CSF) levels, flow cytometry for CCR3(+), VLA4(+), and CCR3(+)VLA4(+), as well as adhesion assays to VCAM-1 were performed in BM. Prior airway exposure to SEA time dependently increased the BM eosinophil number in OVA-challenged mice. Eosinophils gradually disappear from peripheral blood, being recruited over time to the airways, where they achieve a maximal infiltration at 24 h. SEA exposure increased the levels of IL-5 and eotaxin (but not GM-CSF) in BM of OVA-challenged mice. Marked increases in CCR3(+) and CCR3(+)VLA4(+) expressions in BM eosinophils of OVA-challenged mice were observed, an effect largely reduced by prior exposure to SEA. Adhesion of BM eosinophils to VCAM-1 was increased in OVA-challenged mice, but prior SEA exposure abrogated this enhanced cell adhesion. Accumulation of BM eosinophils by airway SEA exposure takes place through IL-5- and CCR3-dependent mechanisms, along with downregulation of CCR3/VL4 and impaired cell adhesion to VCAM-1.
authors.affiliation: Department of Pharmacology, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil.
authors.forename: Dalize M
authors.initials: DM
authors.lastname: Squebola-Cola
authors.forename: Glaucia C
authors.initials: GC
authors.lastname: Mello
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Pissinatti
authors.forename: André A
authors.initials: AA
authors.lastname: Schenka
authors.forename: Gabriel F
authors.initials: GF
authors.lastname: Anhê
authors.forename: Ivani A
authors.initials: IA
authors.lastname: DeSouza
authors.forename: Antonio
authors.initials: A
authors.lastname: Condino-Neto
authors.forename: Edson
authors.initials: E
authors.lastname: Antunes
mesh_terms: D000485:Allergens / Q000276:immunology* / Q000378:metabolism; D000818:Animals; D001853:Bone Marrow / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D002465:Cell Movement / Q000276:immunology*; D004768:Enterotoxins / Q000276:immunology*; D004802:Eosinophilia / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D004804:Eosinophils / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000276:immunology / Q000378:metabolism; D039041:Integrin alpha4beta1 / Q000276:immunology / Q000378:metabolism; D015848:Interleukin-5 / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000276:immunology; D054397:Receptors, CCR3 / Q000276:immunology / Q000378:metabolism; D012137:Respiratory System / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D019010:Vascular Cell Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism
chemical_list: D000485:Allergens; C515351:Ccr3 protein, mouse; D004768:Enterotoxins; D039041:Integrin alpha4beta1; D015848:Interleukin-5; D054397:Receptors, CCR3; D019010:Vascular Cell Adhesion Molecule-1; C026066:enterotoxin A, Staphylococcal; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D010047:Ovalbumin
keywords: CCR3; IL-5; VCAM-1; VLA4; asthma; eotaxin; ovalbumin