Year: 2012
Type: article
Abstract: OBJECTIVE: To elucidate the effect of smoking on host-bacterial interactions in health and disease using an epithelial cell-culture model.MATERIALS AND METHODS: TERT-immortalized human oral keratinocytes line OKF6/TERT-2 were grown to near-confluence in smoke-treated (test) or untreated (control) media and challenged with smoke-treated (test) or untreated (control) healthy (commensal) and pathogenic subgingival biofilms.Supernatant was collected at 2, 4, 6 and 8 hours and the levels of 27 immune mediators were analyzed by multiplexed bead-based flow cytometry.Generation of reactive oxygen species (ROS) was measured using confocal and phase-contrast microscopy of dihydroethidium (DHE)-derived fluorescence.Cell viability was measured using a fluorescent cytotoxicity assay.Cytokine and ROS levels were compared between test and control groups and across time-points using Repeated-Measures ANOVA in a Generalized Estimating Equation framework.RESULTS: Both pathogenic and commensal biofilms elicited a time-dependent immune response from the epithelial cells (p<0.05,Repeated-Measures ANOVA) and the magnitudes of the responses were similar to those of previous investigations.Smoke exposure resulted in rapid elevations of pro-inflammatory cytokines IL-4 and IL-6, innate immune mediators MIP-1α and MIP-1β, and growth factors PDGF and GM-CSF from commensals.By contrast, smoke exposure led to delayed increase in levels of the antiinflammatory cytokine IL1-RA, pro-inflammatory cytokines IL-1β and IL-4 and the growth factor VEGF in response to pathogens.Smoke exposure also resulted in greater release of ROS in response to pathogens compared to commensal biofilms.No differences were detected in cell viability between groups.ii CONCLUSIONS: Smoking prompts an early, exaggerated pro-inflammatory response to commensal biofilms through both innate and acquired immune pathways, and a similar albeit late response to pathogenic biofilms.We have previously demonstrated that smoking results in early loss of commensals and acquisition of pathogens in subgingival biofilms.The present study suggests that a premature proinflammatory response may result in premature commensal loss, thereby promoting colonization by pathogens.The rapid ROS release in response to commensals combined with late pro-inflammatory response to pathogens may contribute to the severe periodontal destruction observed in this high-risk group and will be explored in future studies.
Author: Samir A. Shah
Institution: The Ohio State University
Language: English
Subfield: Periodontics
Field: Dentistry
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2614454514