title: Sodium Hypochlorite Inactivates Lipoteichoic Acid of Enterococcus faecalis by Deacylation.
abstract: BACKGROUND
  Enterococcus faecalis is a pathogenic gram-positive bacterium closely associated with apical periodontitis. Although sodium hypochlorite (NaOCl) has been used as a common endodontic irrigant to eradicate bacteria in the root canal, it has not been elucidated whether NaOCl attenuates the inflammatory response induced by the E. faecalis virulence factor lipoteichoic acid (EfLTA).
  
  
  METHODS
  Structurally intact EfLTA purified from E. faecalis was treated with NaOCl at various concentrations and time periods. Murine macrophage cell line RAW 264.7 was treated with interferon gamma followed by treatment with intact or NaOCl-treated EfLTA to determine the inducibility of inflammatory mediators such as nitric oxide, interferon gamma-inducible protein 10, and macrophage inflammatory protein-1α. Reporter gene assays assessed by flow cytometry were used to examine the ability of intact or NaOCl-treated EfLTA to activate Toll-like receptor 2 (TLR2), which is known to recognize EfLTA on host cells. Structural damage of EfLTA by NaOCl was examined using silver staining and thin-layer chromatography.
  
  
  RESULTS
  NaOCl-treated EfLTA showed markedly less induction of nitric oxide, interferon gamma-inducible protein 10, and macrophage inflammatory protein-1α in RAW 264.7 cells compared with intact EfLTA. In contrast to intact EfLTA that potently stimulated TLR2 activation, NaOCl-treated EfLTA did not activate TLR2. Structural analysis showed that NaOCl damaged EfLTA structure by deacylation.
  
  
  CONCLUSIONS
  NaOCl deacylates the glycolipid moiety of EfLTA, which fails to activate TLR2, leading to the reduced production of inflammatory mediators.
authors: Department of Oral Microbiology and Immunology, Dental Research Institute, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors: Sun Woong
authors: SW
authors: Hong
authors: Department of Oral Microbiology and Immunology, Dental Research Institute, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors: Jung Eun
authors: JE
authors: Baik
authors: Department of Oral Microbiology and Immunology, Dental Research Institute, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors: Seok-Seong
authors: SS
authors: Kang
authors: Department of Conservative Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
authors: Kee-Yeon
authors: KY
authors: Kum
authors: Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea.
authors: Cheol-Heui
authors: CH
authors: Yun
authors: Department of Oral Microbiology and Immunology, Dental Research Institute, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea. Electronic address: shhan-mi@snu.ac.kr.
authors: Seung Hyun
authors: SH
authors: Han
mesh_terms: D000818:Animals; D016466:CHO Cells; D054405:Chemokine CCL3 / Q000378:metabolism; D054357:Chemokine CXCL10 / Q000378:metabolism; D003412:Cricetulus; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D009569:Nitric Oxide / Q000378:metabolism; D010485:Periapical Periodontitis / Q000382:microbiology; D000067996:RAW 264.7 Cells; D012388:Root Canal Irrigants / Q000494:pharmacology; D012973:Sodium Hypochlorite / Q000494:pharmacology*; D013682:Teichoic Acids / Q000378:metabolism*; D051195:Toll-Like Receptor 2 / Q000378:metabolism
chemical_list: D054405:Chemokine CCL3; D054357:Chemokine CXCL10; D008070:Lipopolysaccharides; D012388:Root Canal Irrigants; D013682:Teichoic Acids; D051195:Toll-Like Receptor 2; D009569:Nitric Oxide; C009900:lipoteichoic acid; D012973:Sodium Hypochlorite
keywords: Apical periodontitis; Enterococcus faecalis; Toll-like receptor 2; lipoteichoic acid; sodium hypochlorite