title: TRAF1 regulates recruitment of lymphocytes and, to a lesser extent, neutrophils, myeloid dendritic cells and monocytes to the lung airways following lipopolysaccharide inhalation.
abstract: Inhaled lipopolysaccharide (LPS) induces an inflammatory response that may contribute to the pathogenesis of asthma and other airway diseases. Here we investigate the role of tumour necrosis factor (TNF) receptor-associated factor 1 (TRAF1) in leucocyte recruitment using a model of LPS-induced lung inflammation in mice. TRAF1(-/-) mice are completely deficient in the recruitment of lymphocytes to the lower respiratory tract after inhalation of LPS. Although TRAF1(-/-) mice display normal early accumulation of neutrophils, dendritic cells and monocytes in the alveolar airspace, they have a significantly reduced recruitment of these cells by 24 hr after inhalation of LPS when compared to wild-type (WT) mice. Despite normal expression of the pro-inflammatory cytokines TNF, interleukin-1 (IL-1) and IL-6 after LPS treatment, TRAF1(-/-) mice displayed decreased expression of intercellular adhesion molecule 1, vascular cell adhesion molecule 1, CCL17 and CCL20 in the lungs, when compared to LPS-treated WT mice. These results suggest that TRAF1 facilitates LPS-induced leucocyte recruitment into the lung airways by augmenting the expression of chemokines and adhesion molecules. Mice lacking TNF receptor 1 (TNFR1) but not TNFR2 show a phenotype similar to the TRAF1(-/-) mice, suggesting that TRAF1 may act downstream of TNFR1. Significantly, we use bone marrow chimeras to demonstrate that expression of TRAF1 by cells resident in the lungs, but not by circulating leucocytes, is necessary for efficient LPS-induced recruitment of leucocytes to the lung airways.
authors.affiliation: CBR Institute for Biomedical Research, Department of Pediatrics, Harvard Medical School, Boston MA 02115, USA.
authors.forename: Michiko K
authors.initials: MK
authors.lastname: Oyoshi
authors.forename: Robert
authors.initials: R
authors.lastname: Barthel
authors.forename: Erdyni N
authors.initials: EN
authors.lastname: Tsitsikov
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000276:immunology; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D015815:Cell Adhesion Molecules / Q000378:metabolism; D018925:Chemokines / Q000378:metabolism; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis; D003713:Dendritic Cells / Q000276:immunology; D007962:Leukocytes / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology*; D008168:Lung / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009000:Monocytes / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D011014:Pneumonia / Q000276:immunology*; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000276:immunology; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction / Q000276:immunology; D047990:TNF Receptor-Associated Factor 1 / Q000276:immunology*
chemical_list: D015815:Cell Adhesion Molecules; D018925:Chemokines; D016207:Cytokines; D008070:Lipopolysaccharides; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D047990:TNF Receptor-Associated Factor 1; C506236:Tnfrsf1a protein, mouse