Interleukin-8 and Intercellular Adhesion Molecule 1 Regulation in Oral Epithelial Cells by Selected Periodontal Bacteria: Multiple Effects of Porphyromonas gingivalis via Antagonistic Mechanisms (original) (raw)
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Journal of Medical Microbiology, 2008
Cysteine proteinases from Porphyromonas gingivalis, or gingipains, are considered to be key virulence factors of the bacterium in relation to periodontal diseases. Incubation of human oral epithelial cells with lysine-specific gingipain (Kgp) and high-molecular-mass arginine-specific gingipain (HRgpA) resulted in a decrease in the production of interleukin (IL)-8, but not in the production of other pro-inflammatory cytokines. In contrast, arginine-specific gingipain 2 (RgpB) increased IL-8 production. RNA interference assays demonstrated that Kgp-and HRgpAmediated downregulation and RgpB-mediated upregulation occurred through protease-activated receptor (PAR)-1 and PAR-2 signalling. Although the RgpB-mediated upregulation of IL-8 production occurred through nuclear factor-kappa B (NF-kB), the Kgp-and HRgpA-mediated downregulation was not negated in NF-kB-silenced cells. Both the haemagglutinin and the enzymic domains are required for Kgp and HRgpA to downregulate the production of IL-8 in human oral epithelial cells, and the two domains are thought to co-exist. These results suggest that gingipains preferentially suppress IL-8, resulting in attenuation of the cellular recognition of bacteria, and as a consequence, sustain chronic inflammation.
Periodontal diseases result from the interaction of bacterial pathogens with the host gingival tissues. The role of gingival epithelial cells in the initiation of host defense mechanisms after encountering oral bacteria has not been investigated. Actinobacillus actinomycetemcomitans is a key periodontal pathogen that adheres to and invades oral epithelial cells. Thus, we examined whether gingival epithelial cells increase secretion of the potent neutrophil chemoattractant interleukin-8 (IL-8) following A. actinomycetemcomitans challenge. Normal human oral keratinocytes (NHOK), isolated from gingival tissue, and 3 oral epithelial cell lines (HOK-18A, HOK-16B-J3aP-Tl, and HEp-2) were co-cultured with A. actinomycetemcomitans for 2 hours to allow bacteria-epithelial cell interactions. The epithelial cells were then washed, and fresh medium with gentamicin was added to kill extracellular bacteria. Cell cultures were further incubated for 24 hours before the supernatant was collected for IL-8 detection with ELISA. The results showed that IL-8 secretion increased 2to 7-fold 24 hours after bacterial challenge. The highest IL-8 secretion was at the multiplicity of infection (MOI) of 1,000:1 in bacterial dose response studies using HOK-16B-BaP-Tl cells. Time-course studies revealed that IL-8 secretion rapidly reached a maximum level 6 hours after bacterial challenge and subsequently decreased to basal levels. These data indicate that gingival epithelial cells are capable of upregulating IL-8 expression rapidly in response to A. actinomycetemcomitans challenge and thus may facilitate the recruitment of neutrophils as a host defense mechanism.
FEBS Letters, 1998
Gingipains are the major cysteine proteinases synthesized by Porphyromonas gingivalis which, in soluble form, are able to initially convert IL-8 (77 amino acid residues) to a more potent species truncated at the amino terminus, followed by slow degradation and destruction of chemokine biological activity. In contrast, the same enzymes when associated with bacterial outermembrane blebs (vesicles), instantly degrade this chemokine. This division of enhancing and inactivating activity between soluble and membrane-bound gingipains can cause the compartmentalization of pro-and anti-inflammatory reactions to distal and proximal positions from bacterial plaque, respectively, which may explain why, despite the massive neutrophil accumulation at periodontitis sites, there is no elimination of infection.
Infection and Immunity, 2008
) and nonimmune (IL-8 77aa ) cells. IL-8 77aa has low chemotactic and respiratory burst-inducing activity but is susceptible to cleavage by gingipains. This study shows that both R-and K-gingipain treatments of IL-8 77aa significantly enhance burst activation by fMLP and chemotactic activity (P < 0.05) but decrease burst activation and chemotactic activity of IL-8 72aa toward neutrophil-like HL60 cells and primary neutrophils (P < 0.05). Using tandem mass spectrometry, we have demonstrated that R-gingipain cleaves 5-and 11-aa peptides from the N-terminal portion of IL-8 77aa and the resultant peptides are biologically active, while K-gingipain removes an 8-aa N-terminal peptide yielding a 69-aa isoform of IL-8 that shows enhanced biological activity. During periodontitis, secreted gingipains may differentially affect neutrophil chemotaxis and activation in response to IL-8 according to the cellular source of the chemokine. dom). All reagents were obtained from Sigma Chemical Company (Poole, United Kingdom) and solvents from Fisher (Loughborough, United Kingdom) unless otherwise stated. RPMI 1640, fetal bovine serum, and penicillin (1,000 U ml Ϫ1 )/streptomycin (10,000 g ml Ϫ1 ) were obtained from GibcoBRL (Paisley, United Kingdom). Recombinant IL-8 72aa , endothelium-derived recombinant IL-8 77aa , and monoclonal anti-human IL-8 antibody, clone 6218, were purchased from R&D systems (Abingdon, United Kingdom).
The host cytokine response to Porphyromonas gingivalis is modified by gingipains
Oral Microbiology and Immunology, 2009
Background/aims-Clinical studies indicate that primary proinflammatory cytokines, such as interleukin-1β (IL-1β) are elevated in the gingival crevice around teeth with periodontitis but the secondary cytokines and chemokines, IL-6 and IL-8, are not. The human gingival epithelial cells (HGECs) lining the gingival sulcus respond to perturbation by microbes of dental plaque by releasing a wide range of cytokines. Porphyromonas gingivalis, a putative periodontal pathogen, possesses numerous virulence factors some of which directly impact on the host response. In the present study, we sought to determine how P. gingivalis influences the inflammatory cytokine responses.
European Journal of Oral Sciences, 2001
Gingival epithelial cells (GEC) are the ®rst cells of the host that encounter the periodontal pathogens, and therefore their role in the initiation of the in¯ammatory response is critical. We aimed to: 1) characterize the expression of interleukin (IL)-1a and IL-1b in human gingiva and cultured GEC; 2) demonstrate the ability of A. actinomycetemcomitans extracts to upregulate IL-1a, IL-1b and IL-8 expression in GEC in vitro; and 3) characterize the role of IL-1a and IL-1b in the induction of IL-8 expression in GEC in vitro. Ten gingival biopsies (5 in¯amed and 5 controls) and cultured GEC were examined for IL-1a and IL-1b using immunohistochemical techniques. GEC were also challenged with A. actinomycetemcomitans extracts or IL-1, and secretion of IL-1 and IL-8 was determined by ELISA. In vivo, IL-1a and IL-1b were localized in the gingival epithelium and the in®ltrating leukocytes. In vitro, A. actinomycetemcomitans extracts induced a time-dependent expression of IL-1a, IL-1b and IL-8 in GEC. IL-1 inhibitors did not affect A. actinomycetemcomitans-induced IL-8, although they inhibited IL-8 induced by IL-1a or IL-1b. In conclusion, GEC are a major source of IL-1a and IL-1b in the periodontium, which in turn induce additional in¯ammatory mediators such as IL-8. Therefore GEC can be a potential target for therapeutic intervention in the future.
Infection and Immunity, 1992
Inflammatory mediators produced by cells in the gingiva have been implicated in the initiation and progression of periodontal disease, a common infectious disease. In this study, we examined the biological activity of neutrophil chemotactic factors and the kinetics of expression of interleukin-8 (IL-8) mRNA derived from normal gingival fibroblasts in response to inflammatory mediators in an in vitro model. Gingival fibroblasts stimulated by either recombinant human interleukin-113 or recombinant human tumor necrosis factor alpha produced neutrophil chemotactic factors after 4 h, whereas expression of cell-derived IL-8 mRNA was detected within 1 h after stimulation. Furthermore, in a neutralization assay, rabbit anti-recombinant human IL-8 antiserum inhibited neutrophil chemotactic activity to basal levels. These results provide evidence that gingival fibroblasts synthesize potent chemotactic factors such as IL-8 in the presence of the inflammatory mediators interleukin-1l and tumor necrosis factor alpha. The activity of these factors may contribute to neutrophil-mediated processes in the pathogenesis of periodontal disease. * Corresponding author. tactic factors, including IL-8, based on reports of fibroblast production of IL-8 in other tissues. These networks of cytokine synthesis may have a role in the progression of periodontal diseases.
Cytokine Responses of Oral Epithelial Cells to Porphyromonas gingivalis Infection
Journal of Dental Research, 2000
Accumulating evidence indicates that epithelia are not merely mechanical barriers but also important elements of the innate immune system. The present study was performed to examine cytokine responses of oral epithelial cells after infection with the periodontal pathogen Porphyromonas gingivalis. The KB-cell line and primary cultures of periodontal pocket epithelium were infected with P. gingivalis for assessment of bacterial invasion by an antibiotic protection assay, and examination of expression of interleukin-1 beta, interleukin-6, interleukin-8, and tumor necrosis factor-alpha by in situ hybridization and immunohistochemistry. We observed that P. gingivalis induces a strong cytokine response, positively correlated with the adhesive/invasive potential of the infecting strain, in both KB cells and primary cultures. These findings indicate that the epithelial cells of the periodontal pocket are an integral part of the immune system, eliciting cytokine responses to a bacterial challenge. In this context, the adhesive/invasive phenotype of P. gingivalis appears to contribute to pathogenicity.