title: Host-Bacterial Interactions in Post-treatment Apical Periodontitis: A Metaproteome Analysis.
abstract: BACKGROUND
  This study evaluated the bacterial and human metaproteome of root apexes and the matched inflammatory lesions from teeth with post-treatment apical periodontitis.
  
  
  METHODS
  Root apexes and matched inflammatory lesions from root canal-treated teeth with apical periodontitis were obtained during periradicular surgery. All root canal fillings were rated as adequate on the basis of radiographs and cone-beam computed tomography. The specimens were cryopulverized and subjected to metaproteomic analysis for human and bacterial proteins by using a mass spectrometry platform that is based on nanoflow liquid chromatography coupled with linear ion trap quadrupole Velos Orbitrap.
  
  
  RESULTS
  The metaproteome analyses revealed the presence of viable and metabolically active human and bacterial cells in both apexes and lesions. Several bacterial proteins of interest for pathogenicity and therapeutics were identified in both apexes and lesions, including proteins related to antibiotic resistance, proteolytic function, stress response, adhesion, and virulence. Many human proteins related to immune defense mechanisms were also detected in both root apex and lesion specimens, including immunoglobulins, complement system, and proteins linked to T-cell and B-cell activation, neutrophil microbicidal processes, antigen recognition/presentation, bone resorption, and protection against tissue damage.
  
  
  CONCLUSIONS
  Occurrence of host defense factors from the innate and adaptive immune responses and bacterial virulence, survival, and resistance proteins in matched root apexes/periradicular inflammatory lesions indicates a complex and dynamic host-pathogen interaction in teeth with post-treatment apical periodontitis.
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil. Electronic address: odontojcp@gmail.com.
authors.forename: José Claudio
authors.initials: JC
authors.lastname: Provenzano
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil; Department of Endodontics, Faculty of Dentistry, Grande Rio University, Duque de Caxias, Rio de Janeiro, Brazil.
authors.forename: Henrique S
authors.initials: HS
authors.lastname: Antunes
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Flávio R F
authors.initials: FR
authors.lastname: Alves
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Isabela N
authors.initials: IN
authors.lastname: Rôças
authors.affiliation: Department of Biochemistry, Chemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Wilber S
authors.initials: WS
authors.lastname: Alves
authors.affiliation: Department of Biochemistry, Chemistry Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Márcia R S
authors.initials: MR
authors.lastname: Silva
authors.affiliation: Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: José F
authors.initials: JF
authors.lastname: Siqueira
mesh_terms: D018829:Adhesins, Bacterial; D000293:Adolescent; D000328:Adult; D000368:Aged; D001402:B-Lymphocytes; D001419:Bacteria / Q000276:immunology / Q000378:metabolism*; D001426:Bacterial Proteins / Q000276:immunology* / Q000378:metabolism*; D018441:Biofilms; D001862:Bone Resorption; D002853:Chromatography, Liquid; D054893:Cone-Beam Computed Tomography / Q000379:methods; D024881:Drug Resistance, Bacterial; D005260:Female; D054884:Host-Pathogen Interactions / Q000276:immunology; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D010485:Periapical Periodontitis / Q000276:immunology / Q000382:microbiology*; D020543:Proteome / Q000032:analysis / Q000276:immunology; D012389:Root Canal Obturation; D013312:Stress, Physiological; D013601:T-Lymphocytes; D019227:Tooth Apex / Q000276:immunology / Q000382:microbiology; D014092:Tooth Root / Q000276:immunology / Q000382:microbiology; D014774:Virulence; D055815:Young Adult
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D020543:Proteome
keywords: Bacterial proteome; cryopulverization; human proteome; mass spectrometry; metaproteome; post-treatment apical periodontitis; treated root canal