title: Enhanced allergic airway disease in old mice is associated with a Th17 response.
abstract: BACKGROUND
  The prevalence of asthma in the elderly is increasing and associated with higher mortality than in children or young adults. However, the effects of age on the development and character of allergic asthma have been understudied. It has been suggested that mixed Th2/Th17 responses cause more severe forms of asthma, but the role of Th17 response in allergic airway disease and aging is not well understood.
  
  
  OBJECTIVE
  To investigate age-dependent characteristics and Th17 immune response in allergic airway disease in a murine house dust mite (HDM)-allergen model.
  
  
  METHODS
  Twelve-week-old and 15-month-old male BALB/c mice were sensitized and challenged with HDM. Bronchoalveolar lavage fluid (BALF), airway inflammation and hyperresponsiveness (AHR), serum immunoglobulin and splenic T cells were assessed. Age-related T cell activation was analyzed in a co-culture with bone marrow-derived dendritic cells (BMDC) and splenic CD4(+) T cells from young and old mice.
  
  
  RESULTS
  Features of allergic airway disease such as mucous cell hyperplasia, infiltration of airway eosinophils and lymphocytes, Th2 cytokine expression and serum IgG1 levels were greater in old compared to young mice. In contrast to the more marked inflammatory/immune responses to HDM in old mice, AHR was greater in young HDM-treated mice. Only the old mice developed airway neutrophil infiltration and a Th17 immune response upon HDM exposure, with increases in BALF cytokines IL-17A and KC, and Th17 cytokine producing T cells in the spleen. Stimulation of CD4(+) T cells and BMDC co-cultures with HDM, resulted in an enhanced Th17 cytokine response in cells isolated from old mice.
  
  
  CONCLUSIONS
  Our findings in mice suggest that the severity and character of allergic airway disease are age dependent, with a bias towards a Th17 immune response with aging. Elderly, asthmatics may be prone to develop severe allergic airway inflammation with a mixed Th2/Th17 immune response.
authors.affiliation: Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI, USA; Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Brandenberger
authors.forename: N
authors.initials: N
authors.lastname: Li
authors.forename: D N
authors.initials: DN
authors.lastname: Jackson-Humbles
authors.forename: C E
authors.initials: CE
authors.lastname: Rockwell
authors.forename: J G
authors.initials: JG
authors.lastname: Wagner
authors.forename: J R
authors.initials: JR
authors.lastname: Harkema
mesh_terms: D000367:Age Factors; D000818:Animals; D001249:Asthma / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis; D003713:Dendritic Cells / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D039981:Pyroglyphidae / Q000276:immunology; D058504:Th17 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology
chemical_list: D016207:Cytokines; D007074:Immunoglobulin G
keywords: Th17; aging; allergic asthma; house dust mite; mice