title: IFN-gamma-inducing factor (IL-18) increases allergic sensitization, serum IgE, Th2 cytokines, and airway eosinophilia in a mouse model of allergic asthma.
abstract: We investigated the effects of IFN-gamma-inducing factor (IL-18) in a ragweed (RW) mouse model of allergic asthma. Administration of IL-18 in conjunction with allergic sensitization and challenge in wild-type, but not IFN-gamma -/- mice, inhibited the bronchoalveolar lavage (BAL) eosinophilia induced by RW challenge, and increased serum levels of RW-specific IgG2a and production of IFN-gamma from splenocytes cultured with RW, indicating a critical role for IFN-gamma in mediating these effects. Paradoxically, the same treatment schedule in WT mice increased serum levels of RW-specific IgE and IgG1, and production of IL-4 and IL-5 from splenocytes cultured with RW. When the effects of the same IL-18 treatment schedule were allowed to mature for 3 wk, the inhibition of lung eosinophil recruitment was replaced by augmentation of lung eosinophil recruitment. In another experiment, IL-18 administered only with allergic sensitization increased BAL eosinophilia and lung expression of IL-5 and IFN-gamma, while IL-18 administered only with RW challenge decreased BAL eosinophilia and increased lung IFN-gamma expression, while lung expression of IL-5 remained unchanged. IL-18 administered without RW or adjuvant to naive mice increased total serum IgE levels. Finally, intrapulmonary administrations of IL-18 plus RW in naive mice dramatically increased Th2 cytokine production, IgE levels, eosinophil recruitment, and airway mucus, demonstrating induction of allergic sensitization. This is the first report demonstrating that IL-18 promotes a Th2 phenotype in vivo, and potently induces allergic sensitization. These results suggest that IL-18 may contribute to the pathogenesis of allergic asthma.
authors.affiliation: Department of Internal Medicine, Division of Allergy and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Wild
authors.forename: A
authors.initials: A
authors.lastname: Sigounas
authors.forename: N
authors.initials: N
authors.lastname: Sur
authors.forename: M S
authors.initials: MS
authors.lastname: Siddiqui
authors.forename: R
authors.initials: R
authors.lastname: Alam
authors.forename: M
authors.initials: M
authors.lastname: Kurimoto
authors.forename: S
authors.initials: S
authors.lastname: Sur
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000502:physiology; D000281:Administration, Intranasal; D000485:Allergens / Q000008:administration & dosage / Q000276:immunology*; D000818:Animals; D001249:Asthma / Q000276:immunology* / Q000473:pathology; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D002465:Cell Movement / Q000276:immunology; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis*; D004195:Disease Models, Animal; D004802:Eosinophilia / Q000276:immunology* / Q000473:pathology; D005260:Female; D007073:Immunoglobulin E / Q000097:blood*; D007274:Injections, Intraperitoneal; D007371:Interferon-gamma / Q000096:biosynthesis; D020382:Interleukin-18 / Q000008:administration & dosage / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D011058:Pollen / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology / Q000378:metabolism*
chemical_list: D000276:Adjuvants, Immunologic; D000485:Allergens; D016207:Cytokines; D020382:Interleukin-18; D007073:Immunoglobulin E; D007371:Interferon-gamma