title: Biologic activity of porphyromonas endodontalis complex lipids.
abstract: BACKGROUND
  Periapical infections secondary to pulpal necrosis are associated with bacterial contamination of the pulp. Porphyromonas endodontalis, a gram-negative organism, is considered to be a pulpal pathogen. P. gingivalis is phylogenetically related to P. endodontalis and synthesizes several classes of novel complex lipids that possess biological activity, including the capacity to promote osteoclastogenesis and osteoclast activation. The purpose of this study was to extract and characterize constituent lipids of P. endodontalis and evaluate their capacity to promote proinflammatory secretory responses in the macrophage cell line, RAW 264.7, as well as their capacity to promote osteoclastogenesis and inhibit osteoblast activity.
  
  
  METHODS
  Constituent lipids of both organisms were fractionated by high-performance liquid chromatography and were structurally characterized using electrospray mass spectrometry or electrospray-mass spectrometry/mass spectrometry. The virulence potential of P. endodontalis lipids was then compared with known biologically active lipids isolated from P. gingivalis.
  
  
  RESULTS
  P. endodontalis total lipids were shown to promote tumor necrosis factor alpha secretion from RAW 264.7 cells, and the serine lipid fraction appeared to account for the majority of this effect. P. endodontalis lipid preparations also increased osteoclast formation from RAW 264.7 cells, but osteoblast differentiation in culture was inhibited and appeared to be dependent on Toll-like receptor 2 expression.
  
  
  CONCLUSIONS
  These effects underscore the importance of P. endodontalis lipids in promoting inflammatory and bone cell activation processes that could lead to periapical pathology.
authors.affiliation: Division of Endodontology, Department of Oral Health and Diagnostic Sciences, School of Dental Medicine, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Mirucki
authors.affiliation: Division of Endodontology, Department of Oral Health and Diagnostic Sciences, School of Dental Medicine, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Mehran
authors.initials: M
authors.lastname: Abedi
authors.affiliation: Division of Endodontology, Department of Oral Health and Diagnostic Sciences, School of Dental Medicine, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Jin
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Division of Endodontology, Department of Oral Health and Diagnostic Sciences, School of Dental Medicine, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Division of Pediatric Dentistry, Department of Craniofacial Sciences, School of Dental Medicine, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Yu-Hsiung
authors.initials: YH
authors.lastname: Wang
authors.affiliation: Division of Endodontology, Department of Oral Health and Diagnostic Sciences, School of Dental Medicine, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Kamran E
authors.initials: KE
authors.lastname: Safavi
authors.affiliation: Department of Immunology, University of Connecticut School of Medicine, University of Connecticut Health Center, Farmington, Connecticut.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Clark
authors.affiliation: Division of Periodontology, Department of Oral Health and Diagnostic Sciences, School of Dental Medicine, University of Connecticut Health Center, Farmington, Connecticut. Electronic address: Nichols@nso.uchc.edu.
authors.forename: Frank C
authors.initials: FC
authors.lastname: Nichols
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D002518:Ceramides / Q000032:analysis / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005260:Female; D018836:Inflammation Mediators / Q000032:analysis; D008055:Lipids / Q000032:analysis / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010006:Osteoblasts / Q000187:drug effects; D010010:Osteoclasts / Q000187:drug effects; D010714:Phosphatidylethanolamines / Q000032:analysis / Q000494:pharmacology; D045202:Porphyromonas endodontalis / Q000737:chemistry*; D016966:Porphyromonas gingivalis / Q000737:chemistry; D012694:Serine / Q000032:analysis / Q000494:pharmacology; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013109:Sphingomyelins / Q000032:analysis / Q000494:pharmacology; D053719:Tandem Mass Spectrometry / Q000379:methods; D051195:Toll-Like Receptor 2 / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects; D037521:Virulence Factors / Q000494:pharmacology
chemical_list: D002518:Ceramides; D018836:Inflammation Mediators; D008055:Lipids; D010714:Phosphatidylethanolamines; D013109:Sphingomyelins; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D014409:Tumor Necrosis Factor-alpha; D037521:Virulence Factors; C109343:dihydroceramide; C060281:ceramide phosphoethanolamine; C483858:phosphatidylethanolamine; D012694:Serine
keywords: Electrospray mass spectrometry; Porphyromonas endodontalis; RAW 264.7 cells; osteoblast; osteoclastogenesis