lipid-a and Dental-Plaque

The present study tested the hypothesis that treatment-resistant periodontitis patients present with a more intense inflammatory response to marginal bacterial plaque as a sign of an inflammatory overreaction. Patients with severe marginal periodontitis (Gingival Index > 20%) who had not responded to treatment showed almost no positive response to lipid A in a skin-prick test, which was significantly different from the results from patients with severe marginal periodontitis who had responded to treatment and from healthy control individuals without marginal periodontitis. This finding can be interpreted as an impaired inflammatory reactivity to periodontitis pathogens in treatment-resistant patients, rejecting the hypothesis.

Topics: Adult; Bacteria, Anaerobic; Chronic Disease; Dental Plaque; Female; Humans; Lipid A; Male; Middle Aged; Outcome Assessment, Health Care; Periodontitis; Prognosis; Skin Tests

Regulation of lipopolysaccharide (LPS) chemical composition, particularly its lipid A domain, is an important, naturally occurring mechanism that drives bacteria-host immune system interactions into either a symbiotic or pathogenic relationship. Members of the subgingival oral microbiota can critically modulate host immuno-inflammatory responses by synthesizing different LPS isoforms. The objectives of this study were to analyze subgingival lipid A profiles and endotoxin activities in periodontal health and disease and to evaluate the use of the recombinant factor C assay as a new, lipid A-based biosensor for personalized, point-of-care periodontal therapy.. Subgingival plaque samples were collected from healthy individuals and chronic periodontitis patients before and after periodontal therapy. Chemical composition of subgingival lipid A moieties was determined by ESI-Mass Spectrometry. Endotoxin activity of subgingival LPS extracts was assessed using the recombinant factor C assay, and their inflammatory potential was examined in THP-1-derived macrophages by measuring TNF-α and IL-8 production.. Characteristic lipid A molecular signatures, corresponding to over-acylated, bi-phosphorylated lipid A isoforms, were observed in diseased samples. Healthy and post-treatment samples were characterized by lower m/z peaks, related to under-acylated, hypo-phosphorylated lipid A structures. Endotoxin activity levels and inflammatory potentials of subgingival LPS extracts from periodontitis patients were significantly higher compared to healthy and post-treatment samples.. This is the first study to consider structure-function-clinical implications of different lipid A isoforms present in the subgingival niche and sheds new light on molecular pathogenic mechanisms of subgingival biofilm communities.. Subgingival endotoxin activity (determined by lipid A chemical composition) could be a reliable, bacterially derived biomarker and a risk assessment tool for personalized periodontal care.

Topics: Bacteria; Chronic Periodontitis; Dental Plaque; Endotoxins; Humans; Lipid A; Microbiota; Periodontitis

Recent reports indicate that Porphyromonas gingivalis mediates alveolar bone loss or osteoclast modulation through engagement of Toll-like receptor 2 (TLR2), though the factors responsible for TLR2 engagement have yet to be determined. Lipopolysaccharide (LPS) and lipid A, lipoprotein, fimbriae, and phosphorylated dihydroceramides of P. gingivalis have been reported to activate host cell responses through engagement of TLR2. LPS and lipid A are the most controversial in this regard because conflicting evidence has been reported concerning the capacity of P. gingivalis LPS or lipid A to engage TLR2 versus TLR4. In the present study, we first prepared P. gingivalis LPS by the Tri-Reagent method and evaluated this isolate for contamination with phosphorylated dihydroceramide lipids. Next, the lipid A prepared from this LPS was evaluated for the presence of phosphorylated dihydroceramide lipids. Finally, we characterized the lipid A by the matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and electrospray-MS methods in order to quantify recovery of lipid A in lipid extracts from diseased teeth or subgingival plaque samples. Our results demonstrate that both the LPS and lipid A derived from P. gingivalis are contaminated with phosphorylated dihydroceramide lipids. Furthermore, the lipid extracts derived from diseased teeth or subgingival plaque do not contain free lipid A constituents of P. gingivalis but contain substantial amounts of phosphorylated dihydroceramide lipids. Therefore, the free lipid A of P. gingivalis is not present in measurable levels at periodontal disease sites. Our results also suggest that the TLR2 activation of host tissues attributed to LPS and lipid A of P. gingivalis could actually be mediated by phosphorylated dihydroceramides.

Topics: Carbohydrate Conformation; Ceramides; Dental Plaque; Humans; Lipid A; Lipopolysaccharides; Periodontitis; Porphyromonas gingivalis; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tooth

In our previous study, we found that the ability of supragingival plaque to induce Toll-like receptor (TLR)4-mediated stimulation was positively associated with plaque score and bleeding on probing (BOP) at the sampled sites and that the ability to induce TLR2-mediated stimulation was negatively associated with probing depth (PD) and clinical attachment level (CAL). Because signaling from TLR leads to the induction of pro- and anti-inflammatory cytokines, we further analyzed the influence of the ability of supragingival plaque to induce TLR2-/TLR4-mediated stimulation of cytokine production by peripheral blood mononuclear cells (PBMCs).. The abilities of 125 plaque samples to induce TLR2- or TLR4-mediated stimulation were determined using genetically engineered Chinese hamster ovary reporter cells that express a reporter molecule upon activation of nuclear factor-kappa B through TLR2 or TLR4. PBMCs were stimulated with each plaque sample, and the production of proinflammatory cytokines (tumor necrosis factor-alpha and interleukin [IL]-6 and -8) and an anti-inflammatory cytokine (IL-10) was analyzed by enzyme-linked immunosorbent assay.. The levels of the cytokines produced by PBMCs all correlated with the ability of supragingival plaque to induce TLR4-mediated stimulation but not with its ability to induce TLR2-mediated stimulation. Cytokine production was inhibited by an anti-TLR4 monoclonal antibody and a TLR4 antagonist, compound 406. The levels of cytokines were associated with plaque index, BOP, PD, and CAL at the sampled sites.. The production of pro-/anti-inflammatory cytokines by PBMCs was associated with the ability of supragingival plaque to induce TLR4-mediated stimulation. The cytokines induced by supragingival plaque via TLR4 might modulate periodontal status.

Topics: Adult; Aged; Aged, 80 and over; Animals; Antibodies, Monoclonal; CHO Cells; Cricetinae; Cricetulus; Cytokines; Dental Plaque; Dental Plaque Index; Female; Gingival Hemorrhage; Glycolipids; Humans; Interleukin-10; Interleukin-6; Interleukin-8; Leukocytes, Mononuclear; Lipid A; Male; Middle Aged; NF-kappa B; Periodontal Attachment Loss; Periodontal Index; Periodontal Pocket; Toll-Like Receptor 2; Toll-Like Receptor 4; Tumor Necrosis Factor-alpha; Young Adult