Inter-relationships between rheumatoid arthritis and periodontal disease. A review

Porphyromonas gingivalis may play an important role in the pathogenesis of periodontitis-associated rheumatoid arthritis

Rheumatoid arthritis (RA) is a common, systemic autoimmune disease which leads to destruction of the joint architecture and consequent disability. Although the aetiology of RA remains unknown, accumulating studies have established a strong association between RA and periodontitis (PD). Recently, anti-cyclic citrullinated peptide (anti-CCP) autoantibody and citrullinated peptide have been realized to be involved in the breaking of self-tolerance and development of autoimmune in RA. The citrullinated peptide is generated by post-translational modification (citrullination) of protein-bound arginine by peptidylarginine deiminase (PAD). Porphyromonas gingivalis(P. gingivalis), the major aetiological agent of PD and the only bacterium known to express a PAD enzyme, has been reported to be significantly associated with RA. The antibody titers to P. gingivalis are significantly increased in patients with RA and P. gingivalis antibody titers are significantly correlated with anti-CCP antibody isotypes that are specific to RA. Recent study indicates that the major synovial targets of the RA-specific anti-CCP autoantibodies are deiminated forms of the alpha- and beta- chains of fibrin. Meanwhile, it is also confirmed that bacterial PAD produced by P. gingivalis has the capacity of deiminating arginine in fibrin found in the periodontal lesion. What's more, it has been demonstrated that citrullination of HLA binding peptide causes a 100-fold increase in peptide-MHC affinity and leads to the activation CD4(+)T cells in HLA DRB1 0401 transgenic mice. Therefore, we postulate that P. gingivalis may play a crucial role in the pathogenesis of periodontitis-associated RA. P. gingivalis, which colonizes in the oral cavity, produces PAD enzyme continuously that leads to the citrullination of RA autoantigen such as fibrin in synovium joint. These PAD engendered antigens, presented in association with major histocompatibility complex (MHC) molecules by antigen-presenting cells (APC), ultimately lead to production of the anti-CCP antibody. The anti-CCP antibodies form immune complexes with citrullinated proteins, which can be bound by inflammatory cells via their Fc receptors. The roles of these immune complexes and inflammatory cells are mediated by a complex cascade involving complement activation. These mechanisms result in a release of mediators of inflammation and joint destruction ultimately leading to the onset of RA. This hypothesis reveals that oral bacterial infection may play a role in peptide citrullination which might be involved in loss of self-tolerance and development of autoimmune in RA.

Antibody responses to Porphyromonas gingivalis (P. gingivalis) in subjects with rheumatoid arthritis and periodontitis

Antibody titers to P. gingivalis are increased in patients with rheumatoid arthritis and are associated with disease-specific autoimmunity.

BACKGROUND

Periodontitis (PD) has been implicated as a risk factor for rheumatoid arthritis (RA). We sought to characterize antibody titers to P. gingivalis (a pathogen in PD) in subjects with RA, PD, and in healthy controls and to examine their relationship with disease autoantibodies.

METHODS

P. gingivalis antibody was measured in subjects with RA (n=78), PD (n=39), and in controls (n=40). Group frequencies of bacterial titer elevations were compared using the Chi-square test and antibody titers were compared using non-parametric tests. Correlations of P. gingivalis titer with C-reactive protein (CRP), antibody to cyclic citrullinated peptide (anti-CCP), and rheumatoid factor (RF) were examined in those with RA while CRP and autoantibody concentrations were compared based on seropositivity to P. gingivalis.

RESULTS

Antibody titers to P. gingivalis were highest in PD, lowest in controls, and intermediate in RA (p=0.0003). Elevations in P. gingivalis (titer> or =800) were more common in RA and PD (67% and 77%, respectively) than in controls (40%) (p=0.002). In RA, there were significant correlations with P. gingivalis titer with CRP, anti-CCP-IgM, and -IgG-2. CRP (p=0.006), anti-CCP-IgM (p=0.01) and -IgG2 (p=0.04) concentrations were higher in RA cases with P. gingivalis titers > or =800 compared to cases with titers <800.

CONCLUSION

Antibodies to P. gingivalis are more common in RA subjects than controls, although lower than that in PD. Associations of P. gingivalis titers with RA-related autoantibody and CRP concentrations suggests that infection with this organism plays a role in disease risk and progression in RA.

Acute stress induces proinflammatory signaling at chronic inflammation sites

OBJECTIVES

To analyze in a randomized controlled study whether acute psychological stress alters local proinflammatory signals in a human model of chronic inflammation, i.e., gingivitis. Chronic inflammation represents a crucial factor in a variety of diseases and factors that contribute to the onset and progression of disease. Psychological stress is assumed to represent such a factor. However, experimental human research in this area is rare.

METHODS

A total of 25 students (n = 11 females, 14 males) suffering from gingivitis were subjected to a stress (public-speaking task) and to a control condition in randomized order. Local concentrations of interleukin (IL)-8 were quantified as an indicator of proinflammatory activity at sites of inflammation. IL-8 is a strong proinflammatory mediator and involved in a variety of disease processes. Samples were taken at sites of inflammation before stress versus control condition and 0, 45, and 90 minutes afterward.

RESULTS

A significant main effect (p = .03) of acute stress on local IL-8 was found. Stress induced an increase of IL-8-concentrations; univariate effect sizes varied between d = 0.23 and d = 0.36.

CONCLUSION

This is the first human experimental in vivo study demonstrating that psychological stress alters the local concentrations of IL-8 under conditions of chronic inflammation. It provides direct evidence acute stress is involved in the regulation of local proinflammatory responses in chronic inflammation. Future studies should now explore the effects of more enduring stress conditions and the factors mediating stress effects on inflammatory signals.

Expression of FcgammaRs and mCD14 on polymorphonuclear neutrophils and monocytes may determine periodontal infection

Variance in expression of receptors for immunoglobulin G (FcgammaRs), complement (CR3) and lipopolysaccharide (mCD14) on polymorphonuclear neutrophils (PMNs) and monocytes might affect susceptibility for infection with certain pathogens in periodontitis, a chronic infectious disease of tooth-supportive tissues. Levels of FcgammaRI, IIa, III, CR3 and mCD14 on PMNs and monocytes were measured in 19 periodontitis patients and 18 healthy controls. Subgingival infection with Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) was determined. Activation of PMNs and monocytes in response to stimulation with Aa and Pg was assessed by means of change in mCD14 expression. Periodontitis is associated with an enrichment of the FcgammaRIII(+) monocytes (P = 0.015) with concomitant low mCD14 (P = 0.001). Unadjusted data showed that the subjects culture-positive for Aa (Aa(+)) had significantly lower expression of monocytic FcgammaRI (P = 0.005) and FcgammaRIIa (P = 0.015) than Pg(+) subjects. The FcgammaRI was still lower on monocytes from Aa(+) subjects after adjusting for the background factors (P = 0.037). PMNs from Aa(+) subjects responded in a hyper-reactive manner, in particular when stimulated with Aa (P = 0.011). Lower FcgammaRs expression by monocytes is related to a higher susceptibility of a subject to become infected with Aa. The higher proportion of FcgammaRIII(+) monocytes may be involved in the chronicity of this condition. Hyper-reactive PMNs in Aa(+) subjects may contribute to accelerated breakdown of tooth-supportive tissues.

Association among rheumatoid arthritis, oral hygiene, and periodontitis

BACKGROUND

A limited number of studies suggest a higher prevalence of periodontal disease among individuals with rheumatoid arthritis (RA); however, results have been inconsistent. Further, it is unclear to what extent poor oral hygiene among patients with RA may account for this association.

METHODS

The association between RA and periodontitis was examined in 57 subjects with RA and 52 healthy controls, matched by age and gender. Oral examination included plaque index (PI), gingival index (GI), probing depth (PD), and clinical attachment loss (CAL). Potential risk factors for periodontal disease, such as smoking, education, alcohol consumption, and body mass index (BMI), as well as chronic diseases associated with RA and periodontal disease were assessed through questionnaires.

RESULTS

In a stepwise logistic regression, including RA status, age, gender, education, smoking, alcohol consumption, and BMI, only RA status and age remained significant predictors of periodontal disease. Subjects with RA had a significant 8.05-fold increased odds (95% confidence interval: 2.93 to 22.09) of periodontitis compared to controls. The strength of the association was attenuated but remained statistically significant after further adjustment for PI, GI, or both. PI alone accounted for 12.4%, GI alone accounted for 11.1%, and PI and GI combined accounted for 13.4% of the association between RA and periodontitis.

CONCLUSIONS

Subjects with RA have significantly increased periodontal attachment loss compared to controls. Oral hygiene may only partially account for this association.

Blood cell gene expression profiling in subjects with aggressive periodontitis and chronic arthritis

BACKGROUND

Microarray analysis of local and peripheral cells in subjects with immune-inflammatory diseases may identify candidate genes associated with these diseases. The present study identified differentially expressed genes in peripheral blood mononuclear cells (PBMCs) from subjects with untreated localized aggressive periodontitis (LAgP) or generalized aggressive periodontitis (GAgP). Differentially expressed genes were validated in groups of subjects with LAgP, GAgP, juvenile idiopathic arthritis (JIA), or rheumatoid arthritis (RA) and controls.

METHODS

Candidate genes were identified by gene expression profiling of PBMCs using a microarray system in untreated gender-matched subjects with LAgP (N = 2) or GAgP (N = 3) and controls (N = 2) younger than 35 years of age. The microarray results were validated by real-time reverse transcription-polymerase chain reaction (RT-PCR) using PBMCs from 103 individuals, including groups of subjects with LAgP (N = 18), GAgP (N = 27), JIA (N = 10), or RA (N = 23) and controls (N = 25).

RESULTS

Of 53 differentially expressed candidate genes identified in subjects with LAgP, 14 were involved in immune responses and inflammatory processes. Of these, the RT-PCR validation confirmed that Toll-like receptor 2 gene (TLR2) and myomesin 2 gene had a significantly higher expression in subjects with LAgP than in controls. RT-PCR also showed increased expression of TLR2 in subjects with RA. Comparison of subjects with GAgP to controls using microarray analysis identified only three upregulated genes.

CONCLUSION

Several genes upregulated in subjects with LAgP were related to immune responses including TLR2 and myomesin 2.

Beyond good and evil in the oral cavity: insights into host-microbe relationships derived from transcriptional profiling of gingival cells

In many instances, the encounter between host and microbial cells, through a long-standing evolutionary association, can be a balanced interaction whereby both cell types co-exist and inflict a minimal degree of harm on each other. In the oral cavity, despite the presence of large numbers of diverse organisms, health is the most frequent status. Disease will ensue only when the host-microbe balance is disrupted on a cellular and molecular level. With the advent of microarrays, it is now possible to monitor the responses of host cells to bacterial challenge on a global scale. However, microarray data are known to be inherently noisy, which is caused in part by their great sensitivity. Hence, we will address several important general considerations required to maximize the significance of microarray analysis in depicting relevant host-microbe interactions faithfully. Several advantages and limitations of microarray analysis that may have a direct impact on the significance of array data are highlighted and discussed. Further, this review revisits and contextualizes recent transcriptional profiles that were originally generated for the specific study of intricate cellular interactions between gingival cells and 4 important plaque micro-organisms. To our knowledge, this is the first report that systematically investigates the cellular responses of a cell line to challenge by 4 different micro-organisms. Of particular relevance to the oral cavity, the model bacteria span the entire spectrum of documented pathogenic potential, from commensal to opportunistic to overtly pathogenic. These studies provide a molecular basis for the complex and dynamic interaction between the oral microflora and its host, which may lead, ultimately, to the development of novel, rational, and practical therapeutic, prophylactic, and diagnostic applications.

New endogenous anti-inflammatory and proresolving lipid mediators: implications for rheumatic diseases

Prostaglandins and leukotrienes are lipid mediators that carry out pivotal roles in host defense and acute inflammation. Failure to completely resolve an acute inflammatory response can lead to chronic inflammation, scarring, and eventual loss of tissue function. Until recently, it was thought that tissue resolution of acute inflammation was a passive event. However, it is now known than lipoxins, which--like prostaglandins and leukotrienes--are also derived from arachidonic acid, are active anti-inflammatory and proresolution mediators, acting in part by reducing neutrophil entry to the inflammation site and stimulating the uptake of apoptotic polymorphonuclear leukocytes by macrophages. Novel families of locally acting and locally generated mediators derived from omega-3 polyunsaturated fatty acids have also been identified as biosynthetically active components in the resolution phase of inflammation. The new families of chemical mediators are termed 'resolvins' and 'protectins' because individual members of each family are stereospecific in controlling the duration and magnitude of inflammation in animal models. Possible deficiencies in the biosynthesis of lipoxins, resolvins, and protectins, and/or their signal transduction, might underlie some aspects of pathogenesis in chronic inflammatory diseases.

Periodontal Conditions in Rheumatoid Arthritis: Clinical and Radiographic Investigations

Periodontal conditions in 100 dentate adults with rheumatoid arthritis (RA) were compared with those of age and gender matched individuals without rheumatoid arthritis. The clinical parameters for periodontitis included probing pocket depths, attachment loss, gingival inflammation scores, plaque scoresand radiographic bone loss scores. The rheumatoid arthritis group had more missing teeth than the control group and a higher percentage of them had deeper pocketing and loss of periodontal attachment There were no significant differences between the two groups for gingival inflammation and bleeding. There was a tendency to adverse periodontal conditions amongst the rheumatoid arthritis patients with severe periodontal bone loss occurring more frequently than in the controls. The rheumatoid arthritis patients had more dental plaque deposits than the control group, a finding which could indicate a difference in periodontal care. It is suggested that this study provides evidence of a significant association between periodontitis and rheumatoid arthritis.

Interleukin-17: a new paradigm in inflammation, autoimmunity, and therapy

Chronic diseases, such as periodontal disease (PD) and rheumatoid arthritis (RA), are characterized by a robust immune response resulting in unresolved inflammation. Inflammation is mediated by proinflammatory cytokines; recently, a novel subset of T-helper (Th) cells was identified that plays a crucial role in inflammation and autoimmune disease. This population secretes several proinflammatory cytokines, including the novel cytokine interleukin (IL)-17, and, hence, has been termed "Th17." Inflammatory cytokines are implicated in the progression of localized chronic infections, such as PD, and in serious systemic pathologies, such as diabetes, chronic obstructive pulmonary disease, and cardiovascular disease. IL-17 mediates inflammation through a receptor (IL-17R) composed of two subunits, IL-17RA and IL-17RC. Drugs that antagonize inflammatory cytokines are used therapeutically to downregulate immune-mediated pathology in conditions such as RA, although not all patients respond well to this approach. Therefore, identification of potential novel therapeutic targets, such as the IL-17 signaling complex, may be clinically relevant for mitigating inflammatory pathology. However, the manner in which such a therapeutic may influence the onset and progression of PD is poorly understood. Therapeutics that antagonize inflammatory cytokines ameliorate inflammation and bone loss and may have broader implications for individuals with systemic diseases in which inflammation and autoimmunity predominate.

[Comorbidity in rheumatoid arthritis of early onset. Effects on outcome parameters]

Three-year follow-up data of 1,032 patients with recent onset rheumatoid arthritis (RA) were analyzed regarding the frequency of 21 common comorbid chronic conditions and their impact on health outcome (i.e., pain, functional capacity, disease activity, and radiographic joint damage). Multivariate logistic regression analyses were used to calculate age- and gender-adjusted odds ratios for each chronic condition on severe functional capacity (<60% of full function). Comorbidity was already common at the onset of RA, with 72% of the patients having at least one comorbid condition and almost 50% having at least two. Common comorbidities were associated with significantly worse baseline measures in at least three of seven investigated outcome parameters. The more of these conditions patients had, the worse their 3-year outcome. Functional capacity was most sensitive to comorbid conditions. In logistic regression, obesity, hypercholesterolemia, type II diabetes, and osteoporosis resulted in a twofold risk of severe functional limitation (<60% of full function), independent of each other and of age and gender. The impact of comorbidity on measures of disease severity should be considered when used to compare outcome parameters of different RA samples.

Flow cytometric analysis of adherence of Porphyromonas gingivalis to oral epithelial cells

By using fluorescence microscopy, fluorescently labeled Porphyromonas gingivalis W50 was shown to adhere to oral epithelial (KB) cells as discrete cells or small cell aggregates, whereas P. gingivalis ATCC 33277 bound as large cell aggregates. Flow cytometric analysis showed that for P. gingivalis W50 there was a logarithmic relationship between the bacterial cell ratio (BCR), that is the number of bacterial cells to KB cells, and the percentage of KB cells with W50 cells attached. This percentage of KB cells with W50 attached reached a plateau of approximately 84% cells at a BCR of 500:1. In contrast, a quadratic relationship was observed between BCR and the percentage of KB cells with P. gingivalis ATCC 33277 attached, reaching a maximum of 47% at a BCR of 100:1 but decreasing to 7% at a BCR of 1,000:1. The lower binding of ATCC 33277 at high cell concentrations was attributed to autoaggregation. P. gingivalis W50 cells treated with an inhibitor (Nalpha-p-tosyl-L-lysine chloromethyl ketone [TLCK]) of its RgpA-Kgp proteinase-adhesin complex exhibited significantly reduced binding to KB cells than to untreated cells, suggesting a role for proteinase activity in binding to KB cells. Competitive inhibition with purified proteinase-active and TLCK-inactivated RgpA-Kgp complex significantly decreased the adherence of P. gingivalis W50 cells to KB cells. Furthermore, isogenic mutants of P. gingivalis W50 lacking the kgp gene product, but not the rgpA or rgpB gene products, exhibited significantly decreased adherence to KB cells compared to the wild type.

Th1 immune response promotes severe bone resorption caused by Porphyromonas gingivalis

Bacterial infections of the dental pulp result in soft tissue and alveolar bone destruction. It has been suggested that Th1 responses promote disease, whereas Th2 responses are protective. However, other studies have challenged this notion. To address this question, bone destruction was evaluated in mice immunized to develop strong and polarized Th1- or Th2-biased responses to the oral pathogen Porphyromonas gingivalis. Th1 bias was confirmed by the presence of high titers of serum IgG2a and the production of high levels of interferon (IFN)-gamma and no interleukin (IL)-4 by lymph node cells stimulated with P. gingivalis antigens. In contrast, Th2-biased animals had high titer IgG1 and no IgG2a, and their lymph node cells produced high levels of IL-4 but no IFN-gamma. Subsequent infection of the dental pulp with P. gingivalis caused extensive inflammation and alveolar bone destruction in Th1-biased mice, whereas Th2-biased mice and controls developed minimal lesions. Inflammatory granulomas in Th1-biased mice were heavily infiltrated with osteoclasts and had high local expression of IFN-gamma, IL-1alpha, and IL-1beta. Little or no IFN-gamma/IL-1alpha/IL-1beta and no obvious osteoclasts were detected in lesions of Th2-biased and control groups. These results directly demonstrate that specific Th1 responses promote severe infection-stimulated alveolar bone loss.

Regulatory polymorphisms in extracellular matrix protease genes and susceptibility to rheumatoid arthritis: a case-control study

Many extracellular matrix (ECM) proteases seem to be important in rheumatoid arthritis (RA) and regulation of their transcription levels is a critical mechanism for controlling their activity. We have investigated, therefore, whether the best-characterized single nucleotide polymorphisms (SNPs) affecting transcription of the ECM proteases that have been related with joint pathology are associated with RA susceptibility. Nine SNPs in eight genes were selected by bibliographic search, including SNPs in the genes encoding matrix metalloproteinase (MMP)1, MMP2, MMP3, MMP7, MMP9, MMP13, plasminogen activator, tissue type (PLAT) and PAI-1. They were studied in a case-control setting that included 550 RA patients and 652 controls of Spanish ancestry from a single center. Genotyping was performed by single-base extension. Only two of the nine SNPs showed significant association with RA susceptibility. RA patients showed increased frequencies of the -7351 T allele of the gene encoding PLAT (36.4% versus 32.1% in controls, p = 0.026) and the -1306 T allele of the gene encoding MMP2 (24.5% versus 20.3% in controls, p = 0.013). These two alleles seemed to cooperate according to an additive model with respect to increased RA susceptibility (p = 0.004), and they were the low-expression alleles of the respective SNPs in a PLAT enhancer and the MMP2 promoter. These findings are in agreement with previous data suggesting that these two ECM proteases have a protective role in RA pathology. Confirmation of these associations will be needed to support these hypotheses. The remaining SNPs did not show association, either individually or collectively. Therefore, although regulatory SNPs in ECM proteases did not show any major effect on RA susceptibility, it was possible to find modest associations that, if replicated, will have interesting implications in the understanding of RA pathology.

Effect of therapeutic levels of doxycycline and minocycline in the proliferation and differentiation of human bone marrow osteoblastic cells

Semi-synthetic tetracyclines (TCs) have been reported to reduce pathological bone resorption through several mechanisms, although their effect over bone physiological metabolism is not yet fully understood. The present study aims at evaluate the behaviour of osteoblastic-induced human bone marrow cells regarding proliferation and functional activity, in the presence of representative therapeutic concentrations of doxycycline and minocycline. First passage human osteoblastic bone marrow cells were cultured for 35 days in conditions known to favor osteoblastic differentiation. Doxycycline (1-25 micro g/ml) or minocycline (1-50 micro g/ml) were added continuously, with the culture medium, twice a week with every medium change. Cultures were characterised at several time points for cell proliferation and function. Present data showed that 1 micro g/ml of both tetracyclines, level representative of that attained in plasma and crevicular fluid with the standard therapeutic dosage, increased significantly the proliferation of human bone marrow osteoblastic cells without altering their specific phenotype and functional activity. Long-term exposure to these TCs induced a significant increase in the number of active osteoblastic cells that yielded a proportional amount of a normal mineralised matrix, suggesting a potential application in therapeutic approaches aiming to increase bone formation. The presence of higher levels of these agents led to a dose-dependent deleterious effect over cell culture, delaying cell proliferation and differentiation.

A p38alpha selective mitogen-activated protein kinase inhibitor prevents periodontal bone loss

In the oral microbial environment, Gram-negative bacterial derived lipopolysaccharide (LPS) can initiate inflammatory bone loss as seen in periodontal diseases. p38 Mitogen-activated protein kinase (MAPK) signaling is critical to inflammatory cytokine and LPS-induced cytokine expression, which may contribute toward periodontal bone loss. The purpose of this proof-of-principle study was to evaluate the ability of an orally active p38alpha MAPK inhibitor (SD-282) to reduce periopathogenic LPS-induced alveolar bone loss in an experimental rat model. Five groups of Sprague-Dawley rats received one of the following treatments: LPS injected to the palatal gingiva adjacent to the maxillary molars three times per week for 8 weeks, LPS plus two doses of SD-282 (15 or 45 mg/kg) twice daily by oral gavage, or control groups given drug vehicle (1% polyethylene glycol) or SD-282 (45 mg/kg) only. Baseline and 8-week alveolar bone loss was assessed by microcomputed tomography (microCT) and histological examination. LPS induced severe bone loss over this time period, whereas control groups were unchanged from baseline measurements. Both doses of SD-282 showed significant protection from LPS-induced bone loss. Bone area and volumetric analysis of maxillas by microCT indicated significant loss of bone volume with LPS treatment, which was blocked with the p38 inhibitor. Histological examination indicated significantly fewer tartate-resistant acid phosphatase-positive osteoclasts and a significant decrease in interleukin (IL)-6, IL-1beta, and tumor necrosis factor alpha expression in p38 inhibitor-treated groups compared with LPS groups by immunostaining. Results from this in vivo study suggest that orally active p38 MAPK inhibitors can reduce LPS-induced inflammatory cytokine production and osteoclast formation and protect against LPS-stimulated alveolar bone loss.

Evaluation of t-PA, PAI-2, IL-1βand PGE2in gingival crevicular fluid of rheumatoid arthritis patients with periodontal disease

AIMS

This study was undertaken to compare periodontal conditions, gingival crevicular fluid (GCF) levels of tissue-type plasminogen activator (t-PA), its inhibitor plasminogen activator inhibitor-2 (PAI-2), interleukin-1beta (IL-1beta), prostaglandin E(2) (PGE(2)) in rheumatoid arthritis (RA) patients and control groups.

METHODS

Twenty-three RA patients, 17 systemically healthy patients with periodontal disease (PD), and 17 systemically and periodontally healthy subjects were recruited. GCF samples were obtained from two single-rooted teeth. Full-mouth clinical periodontal measurements were recorded at six sites/tooth. GCF samples were analysed using relevant ELISA kits. Data were tested statistically by appropriate tests.

RESULTS

Total amounts of t-PA, PAI-2 and PGE(2) in GCF samples of the healthy control group were significantly lower than the other groups (p<0.05). The RA group exhibited a higher total amount of t-PA in GCF samples than the PD group (p<0.05). PAI-2, IL-1beta and PGE(2) total amounts were similar in RA and PD groups (p>0.05).

CONCLUSION

The coexistence of RA and periodontitis does not seem to affect clinical periodontal findings or systemic markers of RA. Similar inflammatory mediator levels in RA and PD groups, despite the long-term usage of corticosteroids, non-steroidal anti-inflammatory drugs, suggest that RA patients may have a propensity to overproduce these inflammatory mediators.

The additional value of real-time PCR in the quantitative detection of periodontal pathogens

BACKGROUND AND AIM

For the analysis of subgingival plaque, anaerobic bacterial culture has been the gold standard for many years. Currently, molecular microbial techniques have become available to identify and quantify target organisms with high specificity and sensitivity. The technique of real-time polymerase chain reaction(RT-PCR) provides a new tool to detect oral pathogens both in oral and non-oral human infections. The aim of this study was to compare the RT-PCR and anaerobic culture for detection and quantification of six periodontal pathogens in periodontal health and disease.

MATERIAL AND METHODS

Subgingival plaque samples from 259 adult patients with periodontitis and 111 healthy controls were analysed with quantitative anaerobic culture and quantitative RT-PCR for Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Micromonas micros and Fusobacterium spp.

RESULTS

All species were more frequently isolated from patients than controls with both culture and RT-PCR. P. gingivalis, T. forsythia and M. micros appeared significant markers for disease with both techniques. P. intermedia was significantly associated with periodontitis by RT-PCR only (OR 9.7), whereas A. actinomycetemcomitans showed a significant relationship by culture only. The critical differences between culture and RT-PCR were culture-negative/PCR-positive samples which amounted to 7% for A. actinomycetemcomitans, 3% for P. gingivalis, 7% for T. forsythia, 20% for P. intermedia, 6% for M. micros, and 0.8% for Fusobacterium spp. in periodontitis patients and 12%, 3%, 2%, 35%, 14% and 0%, respectively, in the periodontally healthy group. Furthermore, periodontitis individuals had significantly higher amount of all of the test species in the subgingival plaque samples compared with healthy subjects.

CONCLUSION

RT-PCR provides a new rapid diagnostic tool and opens the opportunity to detect small numbers of oral pathogens in clinical specimens, which are under the detection limit by culture technique.

Anti-Neutrophil Cytoplasmic Autoantibodies: A Renewed Paradigm in Periodontal Disease Pathogenesis?

In the past, various models including the autoimmunity model have been proposed to explain the pathogenesis of periodontal diseases. The aim of this review is to introduce the pathogenic role of anti-neutrophil cytoplasmic autoantibodies (ANCAs) in various autoimmune diseases and compare these conditions with periodontal disease to elucidate common pathogenic mechanisms. Also, a novel model to explain the pathogenesis of periodontal disease based on the concept of ANCA-associated autoimmunity is proposed. This encompasses a wide array of biochemical mediators that range from direct and indirect initiators of ANCA production and eventual release of proinflammatory mediators and free radicals, all of which have been implicated in periodontal tissue destruction in the past. In addition, specific links between the typical ANCA-associated diseases and periodontal disease are discussed. Finally, a new paradigm in the periodontal disease-associated destruction is proposed that includes the currently accepted mechanism, namely, the genetic-microbial-host interactions.

Periodontal and hematological characteristics associated with aggressive periodontitis, juvenile idiopathic arthritis, and rheumatoid arthritis

BACKGROUND

Periodontitis shares several clinical and pathogenic characteristics with chronic arthritis, and there is some degree of coexistence. The aims of this study were to elucidate whether patients with localized aggressive periodontitis (LAgP), generalized aggressive periodontitis (GAgP), juvenile idiopathic arthritis (JIA), and rheumatoid arthritis (RA) share periodontal and hematological characteristics distinguishing them from individuals free of diseases.

METHODS

The study population consisted of white adults (<or=35 years old) with LAgP (N=18), GAgP (N=27), JIA (N=10), RA (N=23), and healthy controls (N=25). All individuals underwent a standardized interview, blood sampling, and an intraoral examination, including registration of plaque, bleeding on probing, probing depth (PD), clinical attachment loss (CAL), and alveolar bone loss (ABL) on radiographs. Blood samples were analyzed for erythrocyte fraction, leukocytes and differential counts, erythrocyte sedimentation rate, C-reactive protein (CRP), immunoglobulin (Ig) M and IgA rheumatoid factors (RFs), and antibodies to cyclic citrullinated peptides.

RESULTS

RA patients had a higher percentage of sites with PD>or=4 mm, CAL>or=2 mm, and ABL>or=2 mm compared to controls. The percentage of sites with CAL>or=2 mm significantly correlated with the levels of IgM-RF and IgA-RF. Missing teeth in JIA and RA patients were not lost due to periodontitis. Patients with GAgP showed higher levels of leukocytes, including neutrophils, and CRP compared to controls. In part, JIA and RA patients showed similar results.

CONCLUSIONS

Young adults with RA may develop periodontal destruction, and these patients require professional attention. Both differences and similarities in periodontal and hematological variables were seen in individuals with periodontitis, JIA, and RA.

Cytokine profiles in peripheral blood and whole blood cell cultures associated with aggressive periodontitis, juvenile idiopathic arthritis, and rheumatoid arthritis

BACKGROUND

Cytokines play a key role in the pathogenesis of inflammatory diseases. An obvious question is whether patients with aggressive periodontitis, juvenile idiopathic arthritis, or rheumatoid arthritis share blood cytokine profiles distinguishing them from individuals free of disease.

METHODS

The study population consisted of Danish white adults, <35 years of age, diagnosed with localized aggressive periodontitis (LAgP; N = 18), generalized aggressive periodontitis (GAgP; N = 27), juvenile idiopathic arthritis (JIA; N = 10), or rheumatoid arthritis (RA; N = 23) and healthy individuals with no systemic or oral diseases (control [CTRL]; N = 25). Enzyme-linked immunosorbent assays were used to determine the levels of interleukin (IL)-1alpha, IL-1beta, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-10, tumor necrosis factor (TNF)-alpha, and lymphotoxin (LT)-alpha in peripheral blood (plasma) and unstimulated and stimulated whole blood cell cultures from the same blood collection. Autoantibodies (aAb) to IL-1alpha and IL-6 were quantitated by radioimmunoassay.

RESULTS

Similar patterns of slightly higher IL-10 levels in plasma were found for GAgP and RA patients and in unstimulated cultures for GAgP, RA, and JIA patients. Interestingly, unstimulated cultures also demonstrated similar patterns of higher TNF-alpha levels for these three groups of patients. Similar group patterns of periodontitis patients (LAgP and GAgP) included increased IL-1Ra levels in stimulated cultures, which also showed similar group patterns of arthritis patients (JIA and RA) with respect to higher IL-1alpha and lower LT-alpha levels. Low titers of aAb to IL-1alpha and IL-6 were found in almost all individuals.

CONCLUSION

Patients with aggressive periodontitis and types of arthritis presented with similar components of blood cytokine profiles distinguishing them from individuals free of disease.

Cytokine pattern determines the progression of experimental periodontal disease induced by Actinobacillus actinomycetemcomitans through the modulation of MMPs, RANKL, and their physiological inhibitors

OBJECTIVE

Inflammatory and immune reactions raised in response to periodontopathogens are thought to trigger periodontal tissue destruction. We therefore investigated the expression of matrix metalloproteinases (MMPs) and the osteoclastogenic factor RANKL (receptor activator of nuclear factor-kappaB ligand), their respective inhibitors TIMPs (tissue inhibitors of metalloproteinases) and OPG (osteoprotegerin) and their possible correlation with the expression of inflammatory and regulatory cytokines in the course of experimental periodontal disease in mice.

METHODS

We characterized the time course of leukocyte migration and alveolar bone loss in C57BL/6 mice infected with Actinobacillus actinomycetemcomitans. Quantitative polymerase chain reaction (RealTime PCR) and ELISA were performed to determine the expression of MMPs, TIMPs, RANKL, OPG and cathepsin K, interleukin-1beta, tumor necrosis factor-alpha, interferon-gamma, interleukin-12, interleukin-4 and interleukin-10 in periodontal tissue samples harvested throughout the course of experimental disease.

RESULTS

Oral inoculation of A. actinomycetemcomitans results in an intense and widespread migration of leukocytes to the gingival tissues, besides marked alveolar bone resorption. Our data also demonstrate two distinct patterns of MMP/TIMP and RANKL/OPG expression in the course of experimental periodontal disease. The expression of MMPs (MMP-1, 2 and 9) and RANKL was correlated with the expression of interleukin-1beta, tumor necrosis factor-alpha and interferon-gamma, in a time period characterized by the intense increase of inflammatory reaction and alveolar bone loss. On the other hand, interleukin-4 and interleukin-10 were associated with higher expression of TIMPs (TIMP 1, 2 and 3) and OPG, with a lower expression of MMPs and RANKL, and with reduced rates of increase of cellular infiltration in periodontal tissues and alveolar bone loss.

CONCLUSIONS

It is possible that the pattern of cytokines produced in periodontal tissues determines the progression and the severity of experimental periodontal disease, controlling the breakdown of soft and bone tissues through the balance between MMPs/TIMP and RANKL/OPG expression in gingival tissues.

Fos/AP-1 proteins in bone and the immune system

The skeleton and the immune system share a variety of different cytokines and transcription factors, thereby mutually influencing each other. These interactions are not confined to the bone marrow cavity where bone cells and hematopoietic cells exist in proximity but also occur at locations that are target sites for inflammatory bone diseases. The newly established research area termed 'osteoimmunology' attempts to unravel these skeletal/immunological relationships. Studies towards a molecular understanding of inflammatory bone diseases from an immunological as well as a bone-centered perspective have been very successful and led to the identification of several signaling pathways that are causally involved in inflammatory bone loss. Induction of receptor activator of nuclear factor (NF)-kappaB ligand (RANKL) signals by activated T cells and subsequent activation of the key transcription factors Fos/activator protein-1 (AP-1), NF-kappaB, and NF for activation of T cells c1 (NFATc1) are in the center of the signaling networks leading to osteoclast-mediated bone loss. Conversely, nature has employed the interferon system to antagonize excessive osteoclast differentiation, although this counteracting activity appears to be overruled under pathological conditions. Here, we focus on Fos/AP-1 functions in osteoimmunology, because this osteoclastogenic transcription factor plays a central role in inflammatory bone loss by regulating genes like NFATc1 as well as the interferon system. We also attempt to put potential therapeutic strategies for inflammatory bone diseases in perspective.

Hypothesis: the humoral immune response to oral bacteria provides a stimulus for the development of rheumatoid arthritis

Rheumatoid arthritis (RA) and adult periodontitis share common pathogenetic mechanisms and immunologic and pathological findings. One oral pathogen strongly implicated in the pathogenesis of periodontal disease, Porphyromonas gingivalis, possesses a unique microbial enzyme, peptidylarginine deiminase (PAD), the human equivalent of which has been identified as a susceptibility factor for RA. We suggest that individuals predisposed to periodontal infection are exposed to antigens generated by PAD, with de-iminated fibrin as a likely candidate, which become systemic immunogens and lead to intraarticular inflammation. PAD engendered antigens lead to production of rheumatoid factor-containing immune complexes and provoke local inflammation, both in gingiva and synovium via Fc and C5a receptors.

Risk Indicators for Tooth Loss Due to Periodontal Disease

BACKGROUND

Several risk indicators for periodontal disease severity have been identified. The association of these factors with tooth loss for periodontal reasons was investigated in this cross-sectional comparative study.

METHODS

All extractions performed in 21 general dental practice clinics (25% of such clinics in Kuwait) over a 30-day period were recorded. Documented information included patient age and gender, medical history findings, dental maintenance history, toothbrushing frequency, types and numbers of extracted teeth, and the reason for the extraction. Reasons were divided into periodontal disease versus other reasons in univariate and binary logistic regression analyses.

RESULTS

A total of 1,775 patients had 3,694 teeth extracted. More teeth per patient were lost due to periodontal disease than for other reasons (2.8 +/- 0.2 versus 1.8 +/- 0.1; P <0.001). Factors significantly associated with tooth loss due to periodontal reasons in logistic regression analysis were age >35 years (odds ratio [OR] 3.45; 95% confidence interval [CI] 2.79 to 4.26), male gender (OR 1.42; 95% CI 1.17 to 1.73), never having periodontal maintenance (OR 1.48; 95% CI 1.23 to 1.78), never using a toothbrush (OR 1.81; 95% CI 1.49 to 2.20), current or past smoking (OR 1.56; 95% CI 1.28 to 1.91), anterior tooth type (OR 3.23; 95% CI 2.57 to 4.05), and the presence of either of the following medical conditions: diabetes mellitus (OR 2.64; 95% CI 2.19 to 3.18), hypertension (OR 1.73; 95% CI 1.41 to 2.13), or rheumatoid arthritis (OR 4.19; 95% CI 2.17 to 8.11).

CONCLUSION

Tooth loss due to periodontal disease is associated with the risk indicators of age, male gender, smoking, lack of professional maintenance, inadequate oral hygiene, diabetes mellitus, hypertension, rheumatoid arthritis, and anterior tooth type.

Nonsurgical approaches for the treatment of periodontal diseases

This article reviews nonsurgical approaches for the management of periodontal diseases. A brief review of the pathogenesis of periodontitis allows the reader to identify the potential points of intervention. Assessment of risk factors for periodontitis and the potential for risk reduction are introduced as the first part of a three-pronged approach to therapy. Antimicrobial approaches, including the use of mechanical therapy, antiseptics, and antibiotics,are described next. Host modulatory therapy is addressed as the fi-nal component of the nonsurgical approach to periodontal therapy. Clinical applications of these nonsurgical options are presented as part of the treatment strategy.

Sphingosine 1-phosphate acts as a signal molecule in ceramide signal transduction of TNF-alpha-induced activator protein-1 in osteoblastic cell line MC3T3-E1 cells

We previously demonstrated that tumor necrosis factor (TNF)-alpha stimulated the production of activation protein (AP)-1, a transcriptional factor, in mouse osteoblastic MC3T3-E1 cells. Recent studies have shown the importance of ceramide and its metabolites as signal molecules for TNF-alpha-induced gene expression in several cell types. Therefore, our interest was to investigate whether sphingosine metabolites are involved in TNF-alpha-induced signaling in MC3T3-E1 cells. DL-threo-1-phenyl-2-hexadecanoyl-amino-3-pyrrolidino-1-propanol (PPPP), which causes accumulation of intracellular ceramide, stimulated the TNF-alpha-induced expression of the c-fos and c-jun genes. Gel shift assay clearly showed that PPPP increased the cytokine-induced specific binding of nuclear proteins to the 12-tetra-decanoyl phorbol 13-acetate-responsive element (TRE), a consensus sequence for AP-1. In addition, cell-permeable ceramide (N-acetylsphingosine, N-hexanoylsphingosine or N-octanoylsphingosine) stimulated expression of the c-fos and c-jun genes and nuclear protein binding to TRE. Interestingly, DL-threo-dihydrosphingosine (DHS), an inhibitor of sphingosine kinase, clearly blocked the ceramide analogue-induced stimulation. Sphingosine 1-phosphate (SPP) actually induced expression of these oncogenes and activated AP-1. Although TNF-alpha stimulated the AP-1-mediated expression of the monocyte chemoattractant JE/MCP-1, this stimulation was inhibited by DHS. SPP also stimulated JE/MCP-1 gene expression. The present study thus suggests that SPP acts as a signal molecule in ceramide-dependent signal transduction in TNF-alpha-induced AP-1 in osteoblastic MC3T3-E1 cells.

Actinobacillus actinomycetemcomitans-induced periodontal disease in mice: patterns of cytokine, chemokine, and chemokine receptor expression and leukocyte migration

Although the pathogenesis of periodontal disease (PD) is not well known, cytokines, chemotactic factors and inflammatory cells are certainly involved in the disease outcome. Here, we characterized the evolution of the PD induced by Actinobacillus actinomycetemcomitans in mice, showing that oral inoculation of these bacteria leads to the migration of leukocytes to periodontal tissues and marked alveolar bone resorption. We found the expression of pro-inflammatory and Th1-type cytokines including TNF-alpha, IFN-gamma and IL-12 in periodontal tissues after infection with A. actinomycetemcomitans, from the early stages after infection and throughout the course of the disease. Similar kinetics of expression were found for the chemokines CCL5, CCL4, CCL3 and CXCL10 and for the receptors CCR5 and CXCR3, all of them linked to the Th1-type pattern. The expression of the Th2-type mediators IL-10, CCL1 and their receptors CCR4 and CCR8 was detected only after 30 days of infection, determining a time-dependent mixed pattern of polarized immune response. The chemokine expression was correlated with the presence of polymorphonuclear leukocytes, macrophages, CD4 and CD8 lymphocytes, and B cells in the inflammatory infiltrate. Interestingly, during the predominance of the Th1-type response, a sharp increase in the number of inflammatory cells and intense bone loss was seen. By contrast, after the increased expression of Th2-type mediators, the number of inflammatory cells remained constant. Our data demonstrate that mice subjected to oral inoculation of A. actinomycetemcomitans represent a useful model for the study of PD. In addition, our results suggest that expression of cytokines and chemokines can drive the selective recruitment of leukocyte subsets to periodontal tissues, which could determine the stable or progressive nature of the lesion.

Experimental arthritis in rats induces biomarkers of periodontitis which are ameliorated by gene therapy with tissue inhibitor of matrix metalloproteinases

BACKGROUND

Periodontal disease (PD) and rheumatoid arthritis (RA) share many common pathophysiologic features, but a clinical relationship between the two conditions remains controversial, in part because of the confounding effects of anti-inflammatory drug therapy universally used in the latter disease. To further explore this issue, inflammatory arthritis was induced in rats to determine the effect on gingival biomarkers of inflammation and tissue destruction and to investigate the effect of a therapeutic intervention devoid of conventional anti-inflammatory properties.

METHODS

Adjuvant arthritis (AA) was induced in Lewis male rats by injecting mycobacterium cell wall in complete Freund's adjuvant using standard techniques. One group of animals was treated by induction of systemic tissue inhibitor of matrix metalloproteinases (TIMP-4). At 3 weeks, arthritis severity was recorded and both paw and gingival tissues were collected for matrix metalloproteinase activity (MMP) and cytokine analysis. In addition, the maxillary jaws were removed for assessment of periodontal bone loss.

RESULTS

The development of arthritis was associated with elevated joint tissue MMPs, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-1beta levels compared to control rats. In the gingival tissue of the untreated arthritic rats, gelatinase, collagenase, TNF-alpha, and IL-1beta were also elevated compared to control rats. Periodontal bone loss and tooth mobility were also increased significantly (P <0.05) in untreated arthritic rats. All parameters improved after TIMP-4 gene therapy.

CONCLUSIONS

To our knowledge, this is the first study to report an association between experimental systemic arthritis in rats and elevated gingival tissue MMPs, cytokine levels, and periodontal disease. Reversal of these changes with TIMP-4 gene therapy strengthens the pathophysiologic correlation between systemic and local disease.