TLR2-dependent Modulation of Osteoclastogenesis by Porphyromonas gingivalis through Differential Induction of NFATc1 and NF-κB
ABSTRACT Osteolytic diseases, including rheumatoid arthritis, osteomyelitis, and periodontitis, are usually associated with bacterial infections. However, the precise mechanisms by which bacteria induce bone loss still remain unclear. Evidence exists that Toll-like receptor (TLR) signaling regulates both inflammation and bone metabolism and that the receptor activator of NF-κB ligand (RANKL) and its receptor RANK are the key regulators for bone remodeling and for the activation of osteoclasts. Here, we investigate the direct effects of the periodontal pathogen Porphyromonas gingivalis on osteoclast differentiation and show that P. gingivalis differentially modulates RANKL-induced osteoclast formation contingent on the state of differentiation of osteoclast precursors. In addition, although an optimal induction of cytokines by P. gingivalis is dependent on TLR2 and TLR4, as well as myeloid differentiation factor 88 and Toll/IL-1R domain-containing adaptor-inducing IFN-β, P. gingivalis utilizes TLR2/ myeloid differentiation factor 88 in modulating osteoclast differentiation. P. gingivalis modulates RANKL-induced osteoclast formation by differential induction of NFATc1 and c-Fos. More importantly, RANKL-mediated lineage commitment also has an impact on P. gingivalis-induced cytokine production. RANKL inhibits P. gingivalis-induced cytokine production by down-regulation of TLR/NF-κB and up-regulation of NFATc1. Our findings reveal novel aspects of the interactions between TLR and RANK signaling and provide a new model for understanding the mechanism underlying the pathogenesis of bacteria-mediated bone loss.
- SourceAvailable from: PubMed Central[Show abstract] [Hide abstract]
ABSTRACT: The relationship between diabetes mellitus (DM) and periodontal disease is bidirectional. DM is a predisposing and modifying factor of periodontitis, which, in turn, worsens glycemic control and increases proteins found in the acute phase of inflammation, such as C-reactive protein. The gold standard for the treatment of periodontal disease is oral hygiene orientation, scaling and planing. Moreover, systemic antibiotic therapy may be employed in some cases. In an effort to minimize the prescription of antibiotics, photodynamic therapy (PDT) has been studied as an antimicrobial technique and has demonstrated promising results. The aim of the proposed study is to determine whether PDT as a complement to periodontal therapy (PT) is helpful in the metabolic control of individuals with type 2 diabetes and the reduction of acute-phase inflammatory markers. The patients will be randomized using a proper software program into two groups: 1) PT + placebo PDT or 2) PT + active PDT. All patients will first be examined by a specialist, followed by PT performed by two other healthcare professionals. At the end of each session, PDT (active or placebo) will be administered by a fourth healthcare professional. The following will be the PDT parameters: diode laser (660 nm); power output = 110 mW; exposure time = 90 s per point (9 J/point); and energy density = 22 J/cm(2). The photosensitizer will be methylene blue (50 μg/mL). The patients will be re-evaluated 15, 30, 90 and 180 days after treatment. Serological examinations with complete blood count, fasting glucose, glycated hemoglobin and salivary examinations to screen for tumor necrosis factor alpha, interleukin 1, interleukin 6, ostelocalcin, and osteoprotegerin/RANKL will be performed at each evaluation. The data will be statistically evaluated using the most appropriate tests. The results of this study will determine the efficacy of photodynamic therapy as an adjuvant to periodontal treatment in diabetic patients. The protocol for this trial was registered with Clinical Trials registration number NCT01964833 on 14 October 2013.Trials 05/2015; 16(1):229. DOI:10.1186/s13063-015-0757-3 · 2.12 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Background and Objective Periodontal disease is a highly complex chronic inflammatory disease of the oral cavity. Multiple factors influence periodontal disease, including socio-economic status, genetics and age; however, inflammation elicited by the presence of specific bacteria in the subgingival space is thought to drive the majority of soft- and hard-tissue destruction. Porphyromonas gingivalis is closely associated with periodontal disease. Toll-like receptors (TLRs) and their intracellular signaling pathways play roles in the host response to P. gingivalis. The focus of the current study was to use microarray analysis to define the contributions of the TLR adaptor molecules myeloid differentiation factor 88 (MyD88) and Toll/interleukin-1 receptor domain-containing adaptor inducing interferon-beta (TRIF), and aging, on the expression of TLR pathway-associated mRNAs in response to P. gingivalis.Material and Methods Bone marrow-derived macrophages (BMØ) from wild-type (Wt), MyD88 knockout (MyD88-KO) and TrifLps2 [i.e. containing a point mutation in the lipopolysaccharide 2 (Lps2) gene rendering the Toll/interleukin (IL)-1 receptor domain-containing adaptor inducing interferon-beta (TRIF) protein nonfunctional] mice, at 2-and 12-mo of age, were cultured with P. gingivalis. Expression of genes in BMØ cultured with P. gingivalis was determined in comparison with expression of genes in BMØ cultured in medium only.ResultsUsing, as criteria, a twofold increase or decrease in mRNA expression, differential expression of 32 genes was observed when Wt BMØ from 2-mo-old mice were cultured with P. gingivalis compared with the medium-only control. When compared with 2-mo-old Wt mice, 21 and 12 genes were differentially expressed (p < 0.05) as a result of the mutations in MyD88 or TRIF, respectively. The expression of five genes was significantly (p < 0.05) reduced in Wt BMØ from 12-mo-old mice compared with those from 2-mo-old mice following culture with P. gingivalis. Age also influenced the expression of genes in MyD88-KO and TrifLps2 mice challenged with P. gingivalis.Conclusions Our results indicate that P. gingivalis induces differential expression of TLR pathway-associated genes, and both MyD88 and TRIF play roles in the expression of these genes. Age also played a role in the expression of TLR-associated genes following stimulation of BMØ with P. gingivalis.Journal of Periodontal Research 05/2014; 50(1). DOI:10.1111/jre.12185 · 2.22 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Background: Toll-like receptors (TLRs) play pivotal roles in host immune responses and have been suggested to be involved in the development of many infectious diseases. In this study, the mRNA expression levels of TLR2, TLR4, and TLR9 and their relationship with periodontopathic bacteria in periodontal tissue are examined. Furthermore, the mechanism of TLR induction by Porphyromonas gingivalis is investigated in human gingival fibroblasts (HGFs). Methods: Gingival tissue and subgingival plaque samples were collected from 19 patients with chronic periodontitis (CP) and 16 control individuals without periodontitis. Gene expression levels in the tissues and in HGFs were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The numbers of periodontopathic bacteria were determined by quantitative real-time PCR. Results: The expression levels of TLR2 and TLR9 were significantly higher in the tissues of patients with CP compared to the tissues of control individuals. The mRNA levels of TLR2 and TLR9, but not TLR4, were positively correlated with the number of P. gingivalis in subgingival plaque. P. gingivalis sonicated extract, P. gingivalis lipopolysaccharide, P. gingivalis DNA, and tumor necrosis factor-alpha (TNF-alpha) could significantly upregulate the mRNA expression of TLR2 in HGFs. Furthermore, P. gingivalis-mediated TLR2 expression was suppressed by TNF-alpha antibody. Conclusions: This study suggests that P. gingivalis infection induces TLR2 and TLR9 upregulation in patients with CP. P. gingivalis-induced TLR2 expression in HGFs is partially dependent on TNF-alpha and may lead to sensitization of HGFs to bacterial components encountered in the periodontal microenvironment.Journal of Periodontology 07/2013; 84(7):1010-1018. DOI:10.1902/jop.2012.120362 · 2.57 Impact Factor