title: Decreased expression of E-cadherin by Porphyromonas gingivalis-lipopolysaccharide attenuates epithelial barrier function.
abstract: OBJECTIVE
  The gingival epithelium is a first line of defense against bacterial challenge. E-cadherin (E-cad) plays an important role in cell-cell adhesion as a barrier in the epithelium. Recently, a decrease in the expression of E-cad has been observed in inflamed gingival tissue. The aims of this study were to clarify the changes in E-cad expression and barrier function in human gingival epithelial cells stimulated with Porphyromonas gingivalis-lipopolysaccharide (P. gingivalis-LPS) and to evaluate the influence of these changes on the inflammatory reaction. Furthermore, to clarify the mechanism of the E-cad changes induced by P. gingivalis-LPS, we focused on reactive oxygen species (ROS) that are reported to induce a decrease in E-cad expression.
  
  
  METHODS
  Human gingival epithelial cells were incubated in Humedia-KG2 in the presence or absence of P. gingivalis-LPS and antioxidants to analyze ROS involvement in P. gingivalis-LPS-induced E-cad changes. E-cad protein expression was analyzed by immunofluorescence staining. To investigate barrier function and inflammatory changes, we performed transport and cytokine assays using gingival epithelial cells and macrophages co-culture model in transwell plates. Medium containing 10 μg/mL P. gingivalis-LPS (transport substance) was added to the upper compartment, which harvested gingival epithelial cells, and medium without P. gingivalis-LPS was added to the lower compartment, which harvested macrophages. In the transport assay, P. gingivalis-LPS penetration was analyzed using the Limulus amebocyte lysate test. In the cytokine assay, we examined the change in tumor necrosis factor-α (TNF-α) production from the macrophages in the lower compartment using enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Expression of E-cad in human gingival epithelial cells was decreased by P. gingivalis-LPS, and the decrease in E-cad accelerated the penetration of P. gingivalis-LPS through the monolayer. In addition, the concentration of TNF-α was higher under the E-cad reduced monolayer. Antioxidants, particularly vitamin E and l-ascorbic acid 2-phosphate magnesium salt, inhibited the decrease in E-cad expression, penetration of P. gingivalis-LPS and increase in TNF-α.
  
  
  CONCLUSIONS
  These results suggest that the decrease in E-cad caused by P. gingivalis-LPS leads to destruction of the epithelial barrier function in human gingival epithelial cells, and finally accelerates the inflammatory reaction under the barrier. Antioxidants, particularly vitamin E and l-ascorbic acid 2-phosphate magnesium salt, may restore the impaired function by scavenging ROS, which are related to the decrease in E-cad expression by P. gingivalis-LPS.
authors.affiliation: Oral Care Research Laboratories, Lion Corporation, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Abe-Yutori
authors.affiliation: Oral Care Research Laboratories, Lion Corporation, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Chikazawa
authors.affiliation: Oral Care Research Laboratories, Lion Corporation, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Shibasaki
authors.affiliation: Department of Periodontology, Osaka University, Graduate School of Dentistry, Suita, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Murakami
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D015820:Cadherins / Q000096:biosynthesis*; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005881:Gingiva / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D018384:Oxidative Stress; D016966:Porphyromonas gingivalis / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D014810:Vitamin E / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D015820:Cadherins; D016207:Cytokines; D008070:Lipopolysaccharides; D014810:Vitamin E; C011669:ascorbate-2-phosphate; D001205:Ascorbic Acid
keywords: 
  Porphyromonas gingivalis
  ; E-cadherin; epithelial barrier; gingival epithelium; lipopolysaccharide; reactive oxygen species