title: Contrasting immunological effects of two disparate dusts - preliminary observations.
abstract: BACKGROUND
  Modern lifestyle and urbanization have been associated with a raised risk for atopic diseases whereas early and long-term exposure to a farm environment confers protection against atopic sensitization. Immunomodulatory potential and microbiological characteristics of settled airborne dust from an urban house and a barn were examined.
  
  
  METHODS
  Pulmonary inflammation was induced in mice by repeated intranasal administration of dusts. Monocyte-derived human dendritic cells (moDCs) were exposed to dusts followed by coculture with purified naïve T cells. Cytokine/chemokine mRNA and protein levels were analyzed by real-time polymerase chain reaction, enzyme-linked immunosorbent assay and flow cytometry. The dusts were analyzed by cloning and sequencing of 16S rRNA genes (290 sequences) for DNA, lipids, endotoxin and beta-glucan, by live-dead staining, viable counting, isolation and identification of pure cultures (n = 76).
  
  
  RESULTS
  Repeated exposure to house dust elicited pulmonary eosinophilia in mice whereas exposure to barn dust elicited neutrophilic and lymphocytic airway inflammation. Stimulation of moDCs with urban house dust elicited expression of Th2-promoting OX40L and Jagged-1 costimulatory molecules. Dendritic cells (DCs) exposed to house dust directed naïve T cells towards Th2 responses. Exposure of DCs to barn dust elicited the development of Th1-dominated immune responses. Urban house dust contained bacterial debris almost exclusively of human commensal species (corynebacteria, streptococci) whereas barn dust comprised mainly intact, viable bacteria of high diversity and no commensal species.
  
  
  CONCLUSIONS
  Contact to debris originating from human commensal bacteria in urban house dust elicited a Th2-type response whereas barn dust with high bacterial diversity directed the cells towards a Th1 response.
authors.affiliation: Finnish Institute of Occupational Health, Helsinki, Finland. Harri.Alenius@ttl.fi
authors.forename: Harri
authors.initials: H
authors.lastname: Alenius
authors.forename: Jaakko
authors.initials: J
authors.lastname: Pakarinen
authors.forename: Ossian
authors.initials: O
authors.lastname: Saris
authors.forename: Maria A
authors.initials: MA
authors.lastname: Andersson
authors.forename: Marina
authors.initials: M
authors.lastname: Leino
authors.forename: Kristiina
authors.initials: K
authors.lastname: Sirola
authors.forename: Marja-Leena
authors.initials: ML
authors.lastname: Majuri
authors.forename: Jari
authors.initials: J
authors.lastname: Niemela
authors.forename: Sampsa
authors.initials: S
authors.lastname: Matikainen
authors.forename: Henrik
authors.initials: H
authors.lastname: Wolff
authors.forename: Leena
authors.initials: L
authors.lastname: von Hertzen
authors.forename: Mika
authors.initials: M
authors.lastname: Makela
authors.forename: Tari
authors.initials: T
authors.lastname: Haahtela
authors.forename: Mirja
authors.initials: M
authors.lastname: Salkinoja-Salonen
mesh_terms: D016902:Air Pollution, Indoor / Q000009:adverse effects* / Q000032:analysis; D000818:Animals; D001419:Bacteria / Q000276:immunology / Q000302:isolation & purification; D003713:Dendritic Cells / Q000276:immunology / Q000382:microbiology; D004391:Dust / Q000032:analysis / Q000276:immunology*; D005260:Female; D006801:Humans; D001239:Inhalation; D051379:Mice; D008807:Mice, Inbred BALB C; D010802:Phylogeny; D011014:Pneumonia / Q000276:immunology* / Q000382:microbiology; D011657:Pulmonary Eosinophilia / Q000276:immunology / Q000382:microbiology; D013601:T-Lymphocytes / Q000276:immunology / Q000382:microbiology; D018417:Th1 Cells / Q000276:immunology* / Q000382:microbiology; D018418:Th2 Cells / Q000276:immunology* / Q000382:microbiology
chemical_list: D004391:Dust