title: Th2-associated immunity to bacteria in teenagers and susceptibility to asthma.
abstract: Bacterial colonisation of the airways is associated with increased risk of childhood asthma. Immunoglobulin (Ig)E against bacterial antigens has been reported in some asthmatics, suggesting a role for bacterial-specific type-2 immunity in disease pathogenesis. We aimed to investigate relationships between bacterial-specific IgE amongst teenagers and asthma susceptibility. We measured titres of IgE against Haemophilus influenzae, Streptococcus pneumoniae and Staphylococcus aureus in 1,380 teenagers, and related these to asthma symptomatology and immunophenotypes. IgE titres against S. aureus-derived enterotoxins were highest amongst atopics and were associated with asthma risk. Surprisingly, IgE titres against H. influenzae and S. pneumoniae surface antigens were higher, not stratified by atopy and independently associated with decreased asthma risk. The positive association between type-2 immunity to S. aureus and asthma phenotypes probably reflects IgE-mediated effector cell activation via enterotoxin super antigens which are secreted in soluble form. The contrasting benign nature of type-2 immunity to H. influenzae and S. pneumoniae antigens may reflect their lower availability in soluble forms that can crosslink IgE receptors. We theorise that instead they may be processed by antigen presenting cells and presented to type-2 memory cells leading to mucosal secretion of interleukin (IL)-4/IL-13, a mechanism widely recognised in other tissues to attenuate T-helper-1 associated bacterial-induced inflammation.
authors.affiliation: Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Perth, Australia. patrick@ichr.uwa.edu.au
authors.forename: E M
authors.initials: EM
authors.lastname: Hollams
authors.forename: B J
authors.initials: BJ
authors.lastname: Hales
authors.forename: C
authors.initials: C
authors.lastname: Bachert
authors.forename: W
authors.initials: W
authors.lastname: Huvenne
authors.forename: F
authors.initials: F
authors.lastname: Parsons
authors.forename: N H
authors.initials: NH
authors.lastname: de Klerk
authors.forename: M
authors.initials: M
authors.lastname: Serralha
authors.forename: B J
authors.initials: BJ
authors.lastname: Holt
authors.forename: S
authors.initials: S
authors.lastname: Ahlstedt
authors.forename: W R
authors.initials: WR
authors.lastname: Thomas
authors.forename: P D
authors.initials: PD
authors.lastname: Sly
authors.forename: P G
authors.initials: PG
authors.lastname: Holt
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000276:immunology* / Q000382:microbiology*; D016535:Bronchial Hyperreactivity; D005260:Female; D006193:Haemophilus influenzae / Q000276:immunology; D006801:Humans; D007107:Immune System; D007073:Immunoglobulin E / Q000276:immunology; D007249:Inflammation; D008297:Male; D010641:Phenotype; D013147:Spirometry / Q000379:methods; D013211:Staphylococcus aureus / Q000276:immunology; D013296:Streptococcus pneumoniae / Q000276:immunology; D018418:Th2 Cells / Q000166:cytology*; D013997:Time Factors
chemical_list: D007073:Immunoglobulin E