title: Coinfection with Fusobacterium nucleatum can enhance the attachment and invasion of Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans to human gingival epithelial cells.
abstract: OBJECTIVE
  This study was conducted to investigate effects of coinfection of Porphyromonas gingivalis (P. gingivalis) or Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) with Fusobacterium nucleatum (F. nucleatum) on their adhering and invasive capacity to human gingival epithelial cells as well as the expression of interleukin-8 (IL-8) and human beta-defensin-2 (hBD-2) in human gingival epithelial cells.
  
  
  METHODS
  P. gingivalis and A. actinomycetemcomitans were tested for their ability to attach and invade a human gingival epithelial cell line (Ca9-22) alone or coinfecting with F. nucleatum. Also, expression levels of IL-8 and hBD-2 were detected respectively using enzyme linked immunosorbent assay (ELISA) and real-time reverse transcription PCR (RT-PCR) when Ca9-22 cells were infected with P. gingivalis and A. actinomycetemcomitans alone or coinfecting with F. nucleatum.
  
  
  RESULTS
  F. nucleatum, P. gingivalis and A. actinomycetemcomitans were allowed to adhere and invade Ca9-22 cells, either each strain alone or under coinfection. The adhering and invasive abilities of P. gingivalis and A. actinomycetemcomitans were significantly greater when they were coincubated with F. nucleatum (P<0.05) than either of them alone. These enhancements were inhibited by galactose. In addition, P. gingivalis and A. actinomycetemcomitans inhibited the activation of IL-8 and hBD-2 by F. nucleatum. Also, galactose disrupted this inhibition on the expression of IL-8 and hBD-2.
  
  
  CONCLUSIONS
  These results suggested coinfection with F. nucleatum can enhance adhesion and invasion of P. gingivalis and A. actinomycetemcomitans to Ca9-22 cells, as well as inhibition on host innate immune response.
authors.affiliation: School of Stomatology, Shandong University, Jinan, PR China; Shandong provincial key laboratory of oral tissue regeneration, Jinan, PR China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Stomatology, Shandong University, Jinan, PR China; Shandong provincial key laboratory of oral tissue regeneration, Jinan, PR China.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Guo
authors.affiliation: School of Stomatology, Shandong University, Jinan, PR China; Shandong provincial key laboratory of oral tissue regeneration, Jinan, PR China.
authors.forename: Xijun
authors.initials: X
authors.lastname: Wang
authors.affiliation: Jining Medical University.
authors.forename: Yang
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Weifang Medical University.
authors.forename: Chunyu
authors.initials: C
authors.lastname: Yang
authors.affiliation: School of Stomatology, Shandong University, Jinan, PR China; Shandong provincial key laboratory of oral tissue regeneration, Jinan, PR China. Electronic address: yangps@sdu.edu.cn.
authors.forename: Pishan
authors.initials: P
authors.lastname: Yang
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000276:immunology*; D001422:Bacterial Adhesion; D002460:Cell Line; D060085:Coinfection; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000378:metabolism*; D016967:Fusobacterium nucleatum / Q000276:immunology*; D005690:Galactose / Q000494:pharmacology; D005881:Gingiva / Q000166:cytology*; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D016966:Porphyromonas gingivalis / Q000276:immunology*; D060888:Real-Time Polymerase Chain Reaction; D023083:beta-Defensins / Q000378:metabolism
chemical_list: C106641:DEFB4A protein, human; D016209:Interleukin-8; D023083:beta-Defensins; D005690:Galactose
keywords: Aggregatibacter actinomycetemcomitans; Fusobacterium nucleatum; Human beta-defensin-2; Interleukin-8; Periodontitis; Porphyromonas gingivalis