Cigarette smoke extract modulates human beta-defensin-2 and interleukin-8 expression in human gingival epithelial cells.
OBJECTIVE
Human gingival epithelial cells (HGECs) are continually exposed to oral bacteria and to other harmful agents. Their responses to stimuli are critical in maintaining periodontal homeostasis. The aim of this study was to investigate the modulating effect of cigarette smoke extract (CSE) on the innate immune responses of HGECs.


METHODS
Toll-like receptor (TLR) expression of HGECs was determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The effect of CSE or nicotine on the expression of the antimicrobial peptide human beta-defensin-2 (hBD-2) and the pro-inflammatory cytokine interleukin (IL)-8 in stimulated HGEC cultures was evaluated by RT-PCR and enzyme-linked immunosorbent assay.


RESULTS
The HGECs expressed mRNA of TLRs 1, 2, 3, 5, 6, 9, 10, and minimally of TLR4, but not of TLRs 7 or 8. Stimulation of HGECs with highly purified TLR2, 3 or 5 ligands led to expression of hBD-2 and of IL-8. Enhancement of hBD-2 and IL-8 was observed in HGECs after combined stimulation with Porphyromonas gingivalis lipopolysaccharide (TLR2 ligand) and tumour necrosis factor-alpha, compared with stimulation using either agent alone. After CSE exposure, hBD-2 expression was markedly reduced in stimulated HGEC cultures, whereas IL-8 expression was markedly increased. These effects were also observed, but were markedly attenuated, upon nicotine treatment.


CONCLUSIONS
Human gingival epithelial cells play a critical role in orchestrating the innate immune responses of periodontal tissue via TLR signalling. Our results represent the first demonstration that CSE can modulate HGEC function by suppressing hBD-2 and enhancing IL-8 production, and this may be, in part, a possible mechanism which promotes periodontal disease.
Department of Periodontology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. mrangsin@chula.ac.th
R
R
Mahanonda
N
N
Sa-Ard-Iam
M
M
Eksomtramate
P
P
Rerkyen
B
B
Phairat
K E
KE
Schaecher
M M
MM
Fukuda
S
S
Pichyangkul
D000890:Anti-Infective Agents / Q000032:analysis*; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000166:cytology / Q000276:immunology; D005881:Gingiva / Q000166:cytology / Q000276:immunology*; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology; D018836:Inflammation Mediators / Q000032:analysis*; D016209:Interleukin-8 / Q000032:analysis*; D008024:Ligands; D008070:Lipopolysaccharides / Q000494:pharmacology; D009538:Nicotine / Q000494:pharmacology; D018722:Nicotinic Agonists / Q000494:pharmacology; D016966:Porphyromonas gingivalis; D012906:Smoke / Q000032:analysis*; D014026:Nicotiana / Q000737:chemistry*; D051194:Toll-Like Receptor 1 / Q000032:analysis; D051201:Toll-Like Receptor 10 / Q000032:analysis; D051195:Toll-Like Receptor 2 / Q000032:analysis / Q000187:drug effects; D051196:Toll-Like Receptor 3 / Q000032:analysis / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000032:analysis / Q000187:drug effects; D051198:Toll-Like Receptor 5 / Q000032:analysis; D051216:Toll-Like Receptor 6 / Q000032:analysis; D051217:Toll-Like Receptor 9 / Q000032:analysis / Q000187:drug effects; D051193:Toll-Like Receptors / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D023083:beta-Defensins / Q000032:analysis* / Q000187:drug effects
D000890:Anti-Infective Agents; C106641:DEFB4A protein, human; D018836:Inflammation Mediators; D016209:Interleukin-8; D008024:Ligands; D008070:Lipopolysaccharides; D018722:Nicotinic Agonists; D012906:Smoke; C475955:TLR10 protein, human; C495342:TLR2 protein, human; C495344:TLR3 protein, human; C495345:TLR4 protein, human; C495346:TLR5 protein, human; C495368:TLR6 protein, human; C495371:TLR9 protein, human; D051194:Toll-Like Receptor 1; D051201:Toll-Like Receptor 10; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051198:Toll-Like Receptor 5; D051216:Toll-Like Receptor 6; D051217:Toll-Like Receptor 9; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; D023083:beta-Defensins; D009538:Nicotine