Oxygen tension modulates the cytokine response of oral epithelium to periodontal bacteria.
BACKGROUND
There is an inverse relationship between pocket depth and pocket oxygen tension with deep pockets being associated with anaerobic bacteria. However, little is known about how the host tissues respond to bacteria under differing oxygen tensions within the periodontal pocket.


OBJECTIVE
To investigate the effect of different oxygen tensions upon nuclear factor-kappa B (NF-κB) activation and the inflammatory cytokine response of oral epithelial cells when exposed to nine species of oral bacteria.


METHODS
H400 oral epithelial cells were equilibrated at 2%, 10% or 21% oxygen. Cells were stimulated with heat-killed oral bacteria at multiplicity of infection 10:1, Escherichia coli lipopolysaccharide (15 μg/ml) or vehicle control. Interleukin-8 (IL-8) and tumour necrosis factor-alpha (TNF-α) levels were measured by enzyme-linked immunosorbent assay and NF-κB activation was measured by reporter vector or by immunohistochemical analysis.


RESULTS
Tannerella forsythensis, Porphyromonas gingivalis and Prevotella intermedia elicited the greatest epithelial NF-κB activation and cytokine responses. An oxygen-tension-dependent trend in cytokine production was observed with the highest IL-8 and TNF-α production observed at 2% oxygen and lowest at 21% oxygen.


CONCLUSIONS
These data demonstrate a greater pro-inflammatory host response and cell signalling response to bacteria present in more anaerobic conditions, and hypersensitivity of epithelial cells to pro-inflammatory stimuli at 2% oxygen, which may have implications for disease pathogenesis and/or therapy.
Periodontal Research Group, School of Dentistry, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK. m.m.grant@bham.ac.uk
Melissa M
MM
Grant
Rajitha T
RT
Kolamunne
Frances E
FE
Lock
John B
JB
Matthews
Iain L C
IL
Chapple
Helen R
HR
Griffiths
D016924:Actinomyces viscosus / Q000276:immunology; D016976:Aggregatibacter actinomycetemcomitans / Q000276:immunology; D000693:Anaerobiosis; D001439:Bacteroides / Q000276:immunology; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology*; D004847:Epithelial Cells / Q000276:immunology / Q000382:microbiology; D004848:Epithelium / Q000276:immunology / Q000382:microbiology; D004926:Escherichia coli; D016967:Fusobacterium nucleatum / Q000276:immunology; D006801:Humans; D018836:Inflammation Mediators / Q000276:immunology; D016209:Interleukin-8 / Q000032:analysis; D008070:Lipopolysaccharides / Q000494:pharmacology; D009061:Mouth Mucosa / Q000276:immunology / Q000382:microbiology*; D016328:NF-kappa B / Q000032:analysis; D010100:Oxygen / Q000378:metabolism*; D010462:Peptostreptococcus / Q000276:immunology; D010514:Periodontal Pocket / Q000276:immunology / Q000382:microbiology*; D016966:Porphyromonas gingivalis / Q000276:immunology; D018713:Prevotella intermedia / Q000276:immunology; D034361:Streptococcus mitis / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
D016207:Cytokines; D018836:Inflammation Mediators; D016209:Interleukin-8; D008070:Lipopolysaccharides; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D010100:Oxygen