title: Lipoteichoic acid from Lactobacillus plantarum induces nitric oxide production in the presence of interferon-γ in murine macrophages.
abstract: Lipoteichoic acid (LTA) is a major immuno-stimulating component of Gram-positive bacteria. LTA from the beneficial bacterium Lactobacillus plantarum induces weak nitric oxide (NO) production in murine macrophages. Currently, it is not clear if LTA from L. plantarum is able to stimulate the innate immune response, even in the presence of inflammation. In the present study, we prepared highly pure and structurally intact LTA from L. plantarum and investigated its ability to induce NO in the presence of interferon (IFN)-γ in the RAW 264.7 murine macrophage cell line and bone marrow-derived macrophages (BMMs) from mice. L. plantarum LTA alone was unable to induce NO production, even at 30μg/ml. However, LTA in the presence of IFN-γ significantly induced NO production in RAW 264.7 cells. The observed NO production was inhibited by a NO synthase (NOS) inhibitor l-NAME and an inducible NOS (iNOS) inhibitor l-NIL, suggesting that iNOS is specifically required for this action. Western blot analysis and reverse transcription and polymerase chain reaction further confirmed that L. plantarum LTA increased protein and mRNA levels of iNOS, respectively. However, such induction was substantially inhibited in BMMs from Toll-like receptor 2 (TLR2)-deficient mice and the macrophages treated with an inhibitor blocking platelet-activating factor receptor. In addition, L. plantarum LTA plus IFN-γ induced IFN-β expression and STAT1 phosphorylation, which are key pathways for inducing iNOS expression. Electrophoretic mobility shift assay demonstrated that L. plantarum LTA in the presence of IFN-γ remarkably increased the DNA-binding activity of NF-κB transcription factor, which is known to be involved in the iNOS gene expression. Collectively, these results suggest that LTA from L. plantarum alone has no inflammatory potential but does induce NO production under conditions of inflammation, such as the presence of IFN-γ.
authors.affiliation: Department of Oral Microbiology and Immunology, Dental Research Institute, and BK21 Program, School of Dentistry, Seoul National University, Seoul 110-749, Republic of Korea.
authors.forename: Seok-Seong
authors.initials: SS
authors.lastname: Kang
authors.forename: Young Hee
authors.initials: YH
authors.lastname: Ryu
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Baik
authors.forename: Cheol-Heui
authors.initials: CH
authors.lastname: Yun
authors.forename: Kangseok
authors.initials: K
authors.lastname: Lee
authors.forename: Dae Kyun
authors.initials: DK
authors.lastname: Chung
authors.forename: Seung Hyun
authors.initials: SH
authors.lastname: Han
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D024202:Electrophoretic Mobility Shift Assay; D007371:Interferon-gamma / Q000276:immunology* / Q000378:metabolism; D048191:Lactiplantibacillus plantarum / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology* / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000276:immunology; D013682:Teichoic Acids / Q000276:immunology* / Q000378:metabolism
chemical_list: D008070:Lipopolysaccharides; D013682:Teichoic Acids; D009569:Nitric Oxide; C009900:lipoteichoic acid; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II