title: Pulmonary immune responses to Propionibacterium acnes in C57BL/6 and BALB/c mice.
abstract: Propionibacterium acnes (PA) is a gram-positive anaerobic bacterium implicated as a putative etiologic agent of sarcoidosis. To characterize the pulmonary immune response to PA, C57BL/6 and BALB/c mice were intraperitoneally sensitized and intratracheally challenged with heat-killed bacteria. C57BL/6 mice challenged with PA developed a cellular immune response characterized by elevations in Th1 cytokines/chemokines, increased numbers of lymphocytes and macrophages in lung lavage fluid, and peribronchovascular granulomatous inflammation composed of T- and B-lymphocytes and epithelioid histiocytes. T-lymphocytes in the lung lavage fluid showed a marked CD4+ cell predominance. In contrast, C57BL/6 mice challenged with Staphylococcus epidermidis (SE), another gram-positive commensal of human skin, and BALB/c mice challenged with PA, showed only a modest induction of Th1 cytokines, less pulmonary inflammation, and no granulomatous changes in the lung. Enhancement of Toll-like receptor expression was seen in PA-exposed C57BL/6 mice within 24 h after exposure, suggesting that induction of innate immunity by PA contributes to the robust, polarized Th1 immune response elicited by this bacterium. These findings suggest that PA-induced pulmonary inflammation may be a useful model for testing the contributions of both bacterial and host factors in the development, maintenance, and resolution of granulomatous inflammation in the lung.
authors.affiliation: Department of Medicine, Division of Pulmonary Diseases and Cricital Care Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7219, USA.
authors.forename: Joshua G
authors.initials: JG
authors.lastname: McCaskill
authors.forename: Kelly D
authors.initials: KD
authors.lastname: Chason
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Hua
authors.forename: Isabel P
authors.initials: IP
authors.lastname: Neuringer
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Ghio
authors.forename: William K
authors.initials: WK
authors.lastname: Funkhouser
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Tilley
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D016908:Gram-Positive Bacterial Infections / Q000276:immunology* / Q000473:pathology; D008168:Lung / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D008214:Lymphocytes / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D018410:Pneumonia, Bacterial / Q000276:immunology* / Q000473:pathology; D011425:Propionibacterium acnes; D018417:Th1 Cells / Q000276:immunology; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism
chemical_list: D018925:Chemokines; D016207:Cytokines; D051193:Toll-Like Receptors; C488034:ACE protein, human; D007703:Peptidyl-Dipeptidase A