title: Porphyromonas gingivalis lipopolysaccharide weakly activates M1 and M2 polarized mouse macrophages but induces inflammatory cytokines.
abstract: Porphyromonas gingivalis is associated with chronic periodontitis, an inflammatory disease of the tooth's supporting tissues. Macrophages are important in chronic inflammatory conditions, infiltrating tissue and becoming polarized to an M1 or M2 phenotype. As responses to stimuli differ between these phenotypes, we investigated the effect of P. gingivalis lipopolysaccharide (LPS) on M1 and M2 macrophages. M1 and M2 polarized macrophages were produced from murine bone marrow macrophages (BMMϕ) primed with gamma interferon (IFN-γ) or interleukin-4 (IL-4), respectively, and incubated with a low or high dose of P. gingivalis LPS or control TLR2 and TLR4 ligands. In M1-Mϕ, the high dose of P. gingivalis LPS (10 μg/ml) significantly increased the expression of CD40, CD86, inducible nitric oxide synthase, and nitric oxide secretion. The low dose of P. gingivalis LPS (10 ng/ml) did not induce costimulatory or antibacterial molecules but did increase the secretion of IL-1α, IL-6, IL-12p40, IL-12p70, and tumor necrosis factor alpha (TNF-α). P. gingivalis LPS marginally increased the expression of CD206 and YM-1, but it did enhance arginase expression by M2-Mϕ. Furthermore, the secretion of the chemokines KC, RANTES, eotaxin, and MCP-1 from M1, M2, and nonpolarized Mϕ was enhanced by P. gingivalis LPS. TLR2/4 knockout macrophages combined with the TLR activation assays indicated that TLR2 is the main activating receptor for P. gingivalis LPS and whole cells. In conclusion, although P. gingivalis LPS weakly activated M1-Mϕ or M2-Mϕ compared to control TLR ligands, it induced the secretion of inflammatory cytokines, particularly TNF-α from M1-Mϕ and IL-10 from M2-Mϕ, as well as chemotactic chemokines from polarized macrophages.
authors.affiliation: Oral Health CRC, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: James A
authors.initials: JA
authors.lastname: Holden
authors.affiliation: Oral Health CRC, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Troy J
authors.initials: TJ
authors.lastname: Attard
authors.affiliation: Oral Health CRC, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Katrina M
authors.initials: KM
authors.lastname: Laughton
authors.affiliation: Centre for Innate Immunity and Infectious Disease, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia.
authors.forename: Ashley
authors.initials: A
authors.lastname: Mansell
authors.affiliation: Oral Health CRC, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Neil M
authors.initials: NM
authors.lastname: O'Brien-Simpson
authors.affiliation: Oral Health CRC, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne, Victoria, Australia e.reynolds@unimelb.edu.au.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Reynolds
mesh_terms: D000818:Animals; D001119:Arginase / Q000378:metabolism; D051940:B7-2 Antigen / Q000032:analysis; D019013:CD40 Antigens / Q000032:analysis; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000276:immunology*; D008262:Macrophage Activation; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology*; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D016966:Porphyromonas gingivalis / Q000276:immunology*; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D051940:B7-2 Antigen; D019013:CD40 Antigens; C497965:Cd86 protein, mouse; D016207:Cytokines; D008070:Lipopolysaccharides; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D001119:Arginase