title: Exposure of periodontal ligament progenitor cells to lipopolysaccharide from Escherichia coli changes osteoblast differentiation pattern.
abstract: Periodontal ligament mesenchymal stem cells (PDLMSCs) are an important alternative source of adult stem cells and may be applied for periodontal tissue regeneration, neuroregenerative medicine, and heart valve tissue engineering. However, little is known about the impact of bacterial toxins on the biological properties of PDLSMSCs, including self-renewal, differentiation, and synthesis of extracellular matrix.
  
  
  OBJECTIVE
  This study investigated whether proliferation, expression of pro-inflammatory cytokines, and osteogenic differentiation of CD105-enriched PDL progenitor cell populations (PDL-CD105(+) cells) would be affected by exposure to bacterial lipopolysaccharide from Escherichia coli (EcLPS).
  
  
  METHODS
  Toll-like receptor 4 (TLR4) expression was assessed in PDL-CD105(+) cells by the immunostaining technique and confirmed using Western blotting assay. Afterwards, these cells were exposed to EcLPS, and the following assays were carried out: (i) cell viability using MTS; (ii) expression of the interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF-α) genes; (iii) osteoblast differentiation assessed by mineralization in vitro, and by mRNA levels of run-related transcription factor-2 (RUNX2), alkaline phosphatase (ALP) and osteocalcin (OCN) determined by quantitative PCR.
  
  
  RESULTS
  PDL-CD105+ cells were identified as positive for TLR4. EcLPS did not affect cell viability, but induced a significant increase of transcripts for IL-6 and IL-8. Under osteogenic condition, PDL-CD105+ cells exposed to EcLPS presented an increase of mineralized matrix deposition and higher RUNX2 and ALP mRNA levels when compared to the control group.
  
  
  CONCLUSIONS
  These results provide evidence that CD105-enriched PDL progenitor cells are able to adapt to continuous Escherichia coli endotoxin challenge, leading to an upregulation of osteogenic activities.
authors.affiliation: Division of Periodontics, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Mayra Laino
authors.initials: ML
authors.lastname: Albiero
authors.affiliation: Division of Periodontics, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Bruna Rabelo
authors.initials: BR
authors.lastname: Amorim
authors.affiliation: Division of Periodontics, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Luciane
authors.initials: L
authors.lastname: Martins
authors.affiliation: Division of Periodontics, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Márcio Zaffalon
authors.initials: MZ
authors.lastname: Casati
authors.affiliation: Division of Periodontics, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Enilson Antonio
authors.initials: EA
authors.lastname: Sallum
authors.affiliation: Division of Periodontics, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Francisco Humberto
authors.initials: FH
authors.lastname: Nociti
authors.affiliation: Division of Periodontics, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Karina Gonzales
authors.initials: KG
authors.lastname: Silvério
mesh_terms: D015703:Antigens, CD / Q000378:metabolism*; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D016207:Cytokines / Q000032:analysis* / Q000235:genetics; D000071063:Endoglin; D004926:Escherichia coli / Q000378:metabolism*; D006801:Humans; D008070:Lipopolysaccharides / Q000633:toxicity*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects*; D010012:Osteogenesis / Q000502:physiology; D010513:Periodontal Ligament / Q000166:cytology*; D016133:Polymerase Chain Reaction; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018709:Statistics, Nonparametric; D013997:Time Factors; D051197:Toll-Like Receptor 4 / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D016207:Cytokines; C064206:ENG protein, human; D000071063:Endoglin; D008070:Lipopolysaccharides; D011956:Receptors, Cell Surface; D051197:Toll-Like Receptor 4