title: Diverse Toll-like receptors mediate cytokine production by Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans in macrophages.
abstract: Toll-like receptors (TLRs) orchestrate a repertoire of immune responses in macrophages against various pathogens. Fusobacterium nucleatum and Aggregatibacter actinomycetemcomitans are two important periodontal pathogens. In the present study, we investigated TLR signaling regulating cytokine production of macrophages in response to F. nucleatum and A. actinomycetemcomitans. TLR2 and TLR4 are redundant in the production of cytokines (interleukin-6 [IL-6] and tumor necrosis factor alpha [TNF-α]) in F. nucleatum- and A. actinomycetemcomitans-infected macrophages. The production of cytokines by macrophages in response to F. nucleatum and A. actinomycetemcomitans infection was impaired in MyD88-deficient macrophages. Moreover, cytokine concentrations were lower in MyD88-deficient macrophages than in TLR2/TLR4 (TLR2/4) double-deficient cells. An endosomal TLR inhibitor, chloroquine, reduced cytokine production in TLR2/4-deficient macrophages in response to F. nucleatum and A. actinomycetemcomitans, and DNA from F. nucleatum or A. actinomycetemcomitans induced IL-6 production in bone marrow-derived macrophages (BMDMs), which was abolished by chloroquine. Western blot analysis revealed that TLR2/4 and MyD88 were required for optimal activation of NF-κB and mitogen-activated protein kinases (MAPKs) in macrophages in response to F. nucleatum and A. actinomycetemcomitans, with different kinetics. An inhibitor assay showed that NF-κB and all MAPKs (p38, extracellular signal-regulated kinase [ERK], and Jun N-terminal protein kinase [JNK]) mediate F. nucleatum-induced production of cytokines in macrophages, whereas NF-κB and p38, but not ERK and JNK, are involved in A. actinomycetemcomitans-mediated cytokine production. These findings suggest that multiple TLRs may participate in the cytokine production of macrophages against periodontal bacteria.
authors.affiliation: Department of Pathology and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju, South Korea.
authors.forename: Se-Ra
authors.initials: SR
authors.lastname: Park
authors.forename: Dong-Jae
authors.initials: DJ
authors.lastname: Kim
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Han
authors.forename: Min-Jung
authors.initials: MJ
authors.lastname: Kang
authors.forename: Jun-Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Yu-Jin
authors.initials: YJ
authors.lastname: Jeong
authors.forename: Sang-Jin
authors.initials: SJ
authors.lastname: Lee
authors.forename: Tae-Hyoun
authors.initials: TH
authors.lastname: Kim
authors.forename: Sang-Gun
authors.initials: SG
authors.lastname: Ahn
authors.forename: Jung-Hoon
authors.initials: JH
authors.lastname: Yoon
authors.forename: Jong-Hwan
authors.initials: JH
authors.lastname: Park
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000502:physiology*; D000818:Animals; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D005674:Fusobacterium Infections / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D016967:Fusobacterium nucleatum / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D016871:Pasteurellaceae Infections / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism*
chemical_list: D016207:Cytokines; D051193:Toll-Like Receptors