Autopathogenic correlation of periodontitis and rheumatoid arthritis

Prevalence of Microorganisms in Atherosclerotic Plaques of Coronary Arteries: A Systematic Review and Meta-Analysis

Background

In this systematic review and meta-analysis, the existence of pathogens in atherosclerotic plaques of coronary arteries was investigated in coronary arteries diseases (CAD) patients.

Methods

This study was designed and implemented up to 31 August 2020. The findings present according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) checklist. Two independent reviewers (I.RJ and S.H) performed a comprehensive search on four different English databases including PubMed, ISI, Scopus, and Embase. In order to assess the quality of the articles, a checklist prepared by The Joanna Briggs Institute (JBI) was used.

Results

Finally, 44 studies were selected. The prevalence of different microorganisms in coronary arteries were as follows: Aggregatibacter actinomycetemcomitans (46.2%), Campylobacter rectus (43.0%), Chlamydia pneumonia (42.8%), Cytomegalovirus (29.1%), Helicobacter pylori (18.9%), Herpes simplex virus type 1 (5.9%), Porphyromonas gingivalis (42.6%), Prevotella intermedia (47.6%), Tannerella forsythia (43.7%), and Treponema denticola (32.9%).

Conclusion

Based on the result of this meta-analysis, Prevotella intermedia and Aggregatibacter actinomycetemcomitans are the most common microorganisms in atherosclerotic plaques of coronary arteries and may have an important role in the development of atherosclerosis.

Periodontal Treatment for Chronic Periodontitis With Rheumatoid Arthritis

BACKGROUND

History of rheumatoid arthritis (RA) increases risk of periodontal diseases. A pro-inflammatory condition noted in periodontitis is considered a trigger for RA. Thus, periodontal treatment aimed at attenuating the pro-inflammatory state could aid in potentially reducing the risk of RA.

AIMS

The objective of this research was to assess the effect of periodontal therapy on rheumatoid factor, Disease Activity Score-28, anti-citrullinated protein antibody, and C-reactive protein levels in patients with chronic periodontitis (CP) and RA.

MATERIALS AND METHODS

The sample consisted of 28 patients with CP and RA. The study was designed to be a double-blind, randomised controlled clinical study. The samples were randomly categorised to either the treatment group (n = 13) or the control group (n = 15). CP status (plaque index, bleeding on probing, probing pocket depth, clinical attachment loss), clinical rheumatologic status (Disease Activity Score), and biochemical status (C-reactive protein, anti-citrullinated protein antibody, and rheumatoid factor) were assessed at baseline and at follow-up at 8 to 12 weeks.

RESULTS

The treatment group showed a highly statistically significant reduction in bleeding on probing (P < .005), probing pocket depth (P < .001), plaque index (P < .001), and C-reactive protein (P < .001); a gain in the clinical attachment loss (P < .001) and an improvement in Disease Activity Score-28 (P = .001) were observed at reassessment following nonsurgical periodontal treatment as compared to the control group. However, blood serum anti-citrullinated protein antibody (P = .002) and rheumatoid factor levels (P = .351) were found to increase from baseline to 8 to 12 weeks following subgingival scaling and root planing.

CONCLUSIONS

Reduction of inflammation in the periodontium by nonsurgical periodontal therapy did not reduce anti-citrullinated protein antibody and rheumatoid factor levels. However, it has shown improvement in periodontal conditions, and remarkable changes were observed in the clinical Disease Activity Score and C-reactive protein levels of individuals with RA.

The Role of Exposomes in the Pathophysiology of Autoimmune Diseases II: Pathogens

In our continuing examination of the role of exposomes in autoimmune disease, we use this review to focus on pathogens. Infections are major contributors to the pathophysiology of autoimmune diseases through various mechanisms, foremost being molecular mimicry, when the structural similarity between the pathogen and a human tissue antigen leads to autoimmune reactivity and even autoimmune disease. The three best examples of this are oral pathogens, SARS-CoV-2, and the herpesviruses. Oral pathogens reach the gut, disturb the microbiota, increase gut permeability, cause local inflammation, and generate autoantigens, leading to systemic inflammation, multiple autoimmune reactivities, and systemic autoimmunity. The COVID-19 pandemic put the spotlight on SARS-CoV-2, which has been called “the autoimmune virus.” We explore in detail the evidence supporting this. We also describe how viruses, in particular herpesviruses, have a role in the induction of many different autoimmune diseases, detailing the various mechanisms involved. Lastly, we discuss the microbiome and the beneficial microbiota that populate it. We look at the role of the gut microbiome in autoimmune disorders, because of its role in regulating the immune system. Dysbiosis of the microbiota in the gut microbiome can lead to multiple autoimmune disorders. We conclude that understanding the precise roles and relationships shared by all these factors that comprise the exposome and identifying early events and root causes of these disorders can help us to develop more targeted therapeutic protocols for the management of this worldwide epidemic of autoimmunity.

Association between Rheumatoid Arthritis and Poor Self-Perceived Oral Health in Korean Adults

Background and objective: Rheumatoid arthritis (RA) and oral health problems have been reported as specific disease units; however, this study was conducted to evaluate the association between RA and comprehensive oral health status. Therefore, this study aimed to assess the association between RA and oral health using self-perceived oral health (SPOH) variables that can determine the oral health status in Korean adults using representative national data. Methods: Data from 40,186 selected participants were collected from the Korea National Health and Nutrition Examination Survey (KNHANES) between 2007 and 2018. The prevalence relative risk (PRR) was estimated using Poisson regression analysis to obtain the risk ratio of the SPOH according to RA. Results: The risk of SPOH depending on the RA status was statistically significant (odds ratio [OR] = 1.108, 95% confidence interval [CI] 1.005–1.222). In addition, the risk of SPOH depending on the RA status was higher in the group with diabetes mellitus (DM) (OR = 1.205, 95% CI 0.966–1.503) than in the group without DM (OR = 1.088, 95% CI 0.976–1.214). Conclusions: In this study, a significant association was identified between RA and SPOH. Oral health experts should identify the factors affecting the oral health of patients with RA and provide correct oral health care; however, additional research is needed.

Nonsurgical periodontal therapy decreases the severity of rheumatoid arthritis and the plasmatic and salivary levels of RANKL and Survivin: a short-term clinical study

AIM

To investigate the influence of nonsurgical periodontal treatment (NSPT) on clinical periodontal status, rheumatoid arthritis (RA) activity, and plasmatic and salivary levels of biomarkers through a controlled clinical trial on individuals with RA and periodontitis (PE).

METHODS

Sixty-six individuals from a convenience sample were considered eligible and consecutively allocated in 3 groups: (1) individuals without PE and RA (-PE-RA, n = 19); (2) individuals without PE and with RA (-PE+RA, n = 23), and (3) individuals with PE and RA (+PE+RA, n = 24). Full-mouth periodontal clinical examinations, Disease Activity Score (DAS-28) evaluations, and analysis in plasma and saliva of RANKL, OPG, RANKL/OPG, and Survivin were performed at baseline (T1) and 45 days after NSPT (T2).

RESULTS

NSPT in the +PE+RA group was very effective to improve periodontal condition. At T2, significant reductions in DAS-28 were observed in +PE+RA (p = 0.011). Significantly higher levels of Survivin and RANKL were observed in saliva and plasma from RA individuals (with and without PE) compared to controls. Additionally, Survivin e RANKL demonstrated positive correlations with DAS-28 and an expressively significant reduction in +PE+RA at T2 (p < 0.001).

CONCLUSIONS

NSPT was effective on improving both the periodontal and the RA clinical status and reducing the concentration of Survivin and RANKL in saliva and plasma.

PRACTICAL IMPLICATIONS

Nonsurgical periodontal treatment was effective on reducing the concentration of Survivin and RANKL and on improving both the periodontal and the RA clinical status of affected individuals.

TRIAL REGISTRATION

Brazilian Registry of Clinical Trials (ReBEC) protocol #RBR-8g2bc8 ( http://www.ensaiosclinicos.gov.br/rg/RBR-8g2bc8/ ).

Clinical and microbiological effects of non-surgical periodontal treatment in individuals with rheumatoid arthritis: a controlled clinical trial

The effect of periodontal treatment on clinical, microbiological and serological parameters of patients with rheumatoid arthritis (RA) are scarce and controversial. The aim of this study was to investigate the influence of non-surgical periodontal treatment on clinical periodontal status, subgingival bacterial levels of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and RA activity through a controlled clinical trial on individuals with RA and periodontitis (PE). From a convenience sample, 107 individuals were considered eligible and consecutively allocated in four groups: (1) individuals without PE and RA (- PE-RA, n = 30); (2) individuals without PE and with RA (- PE + RA, n = 23); (3) individuals with PE and RA (+ PE + RA, n = 24); and (4) individuals with PE and without RA (+ PE-RA, n = 30). Full-mouth periodontal clinical examinations, microbiological analysis and Disease Activity Score (DAS-28) evaluations were performed at baseline (T1) and 45 days after non-surgical periodontal treatment (T2). At T1, individuals + PE + RA showed greater severity of PE than + PE-RA individuals. At T2, significant reductions were observed in all periodontal clinical parameters in both groups (p < 0.001) with a significant reduction in DAS-28 in + PE + RA (p = 0.011). Individuals + PE-RA and + PE-RA showed significant reductions for all bacteria (p < 0.001). Additionally, P. gingivalis demonstrated an expressively significant reduction in + PE + RA (p < 0.001). Non-surgical periodontal treatment was effective on improving the clinical periodontal condition, improving the RA clinical status and reducing the presence of periodontal pathogens. Brazilian Registry of Clinical Trials (ReBEC) protocol #RBR-8g2bc8 ( https://www.ensaiosclinicos.gov.br/rg/RBR-8g2bc8/ ).

Gingimaps: Protein Localization in the Oral Pathogen Porphyromonas gingivalis

Porphyromonas gingivalis is an oral pathogen involved in the widespread disease periodontitis. In recent years, however, this bacterium has been implicated in the etiology of another common disorder, the autoimmune disease rheumatoid arthritis. Periodontitis and rheumatoid arthritis were known to correlate for decades, but only recently a possible molecular connection underlying this association has been unveiled. P. gingivalis possesses an enzyme that citrullinates certain host proteins and, potentially, elicits autoimmune antibodies against such citrullinated proteins. These autoantibodies are highly specific for rheumatoid arthritis and have been purported both as a symptom and a potential cause of the disease. The citrullinating enzyme and other major virulence factors of P. gingivalis, including some that were implicated in the etiology of rheumatoid arthritis, are targeted to the host tissue as secreted or outer-membrane-bound proteins. These targeting events play pivotal roles in the interactions between the pathogen and its human host. Accordingly, the overall protein sorting and secretion events in P. gingivalis are of prime relevance for understanding its full disease-causing potential and for developing preventive and therapeutic approaches. The aim of this review is therefore to offer a comprehensive overview of the subcellular and extracellular localization of all proteins in three reference strains and four clinical isolates of P. gingivalis, as well as the mechanisms employed to reach these destinations.

Periodontal Condition in Patients with Rheumatoid Arthritis: Effect of Anti-rheumatic Drugs

Statement of the Problem:

Rheumatoid arthritis and periodontitis are chronic inflammatory diseases with a possible bidirectional relationship. This link may be affected by many factors like drug consumption.

Purpose:

This study was designed to evaluate the periodontal condition in patients with rheumatoid arthritis, considering the effect of disease modifying anti-rheumatic drugs.

Materials and Method:

This case-control study included 25 newly diagnosed rheumatoid arthritis patients with negative history of taking anti-rheumatic drugs, 25 patients who received anti-rheumatic drugs for more than three years and 50 healthy individuals as a control group. Periodontal indices, including plaque index, gingival index, probing depth, clinical attachment loss, and rheumatologic indices were recorded and compared between these groups.

Results:

Rheumatoid arthritis patients were significantly more affected by periodontitis compared with healthy subjects (p= 0.006). There was no significant difference in rheumatologic indices between patients with and without periodontitis. Clinical attachment loss in old rheumatoid arthritis patients and gingival index in newly diagnosed ones were significantly more compared to the control group (p= 0.003 and p< 0.001 respectively). We could not find a linear relationship between the severity of rheumatoid arthritis and chronic periodontitis (p= 0.1, r= -0.224).

Conclusion:

Periodontitis and clinical attachment loss were more in patients with rheumatoid arthritis than the healthy group, especially in drug consumers. Gingival index in patients without the history of consuming anti-rheumatic drugs was significantly higher than those who were drug consumers, indicating the effect of the medications on the signs of inflammation.

Linkage of Periodontitis and Rheumatoid Arthritis: Current Evidence and Potential Biological Interactions

The association between rheumatoid arthritis (RA) and periodontal disease (PD) has been the focus of numerous investigations driven by their common pathological features. RA is an autoimmune disease characterized by chronic inflammation, the production of anti-citrullinated proteins antibodies (ACPA) leading to synovial joint inflammation and destruction. PD is a chronic inflammatory condition associated with a dysbiotic microbial biofilm affecting the supporting tissues around the teeth leading to the destruction of mineralized and non-mineralized connective tissues. Chronic inflammation associated with both RA and PD is similar in the predominant adaptive immune phenotype, in the imbalance between pro- and anti-inflammatory cytokines and in the role of smoking and genetic background as risk factors. Structural damage that occurs in consequence of chronic inflammation is the ultimate cause of loss of function and disability observed with the progression of RA and PD. Interestingly, the periodontal pathogen Porphyromonas gingivalis has been implicated in the generation of ACPA in RA patients, suggesting a direct biological intersection between PD and RA. However, more studies are warranted to confirm this link, elucidate potential mechanisms involved, and ascertain temporal associations between RA and PD. This review is mainly focused on recent clinical and translational research intends to discuss and provide an overview of the relationship between RA and PD, exploring the similarities in the immune-pathological aspects and the possible mechanisms linking the development and progression of both diseases. In addition, the current available treatments targeting both RA and PD were revised.

Oral microbial dysbiosis linked to worsened periodontal condition in rheumatoid arthritis patients

Rheumatoid arthritis (RA) is an autoimmune disease characterized by joint inflammation. Individuals with RA have a higher risk of periodontitis and periodontitis has been linked to RA through the production of enzymes by periodontal pathogens that citrullinate proteins. This linkage is supported by findings that periodontitis is associated with increased RA severity and treatment of periodontitis can improve the symptoms of RA. The possible mechanism for this association is through dysbiosis of the oral microbiota triggered by RA-induced systemic inflammation. We examined the RA status of subjects by measuring the number of tender and swollen joints, anti-citrullinated protein antibody and rheumatoid factor. Periodontal disease status and salivary cytokine levels were measured, and dental plaque analyzed by 16S rRNA high throughput sequencing. RA patients had a higher bacterial load, a more diverse microbiota, an increase in bacterial species associated with periodontal disease, more clinical attachment loss, and increased production of inflammatory mediators including IL-17, IL-2, TNF, and IFN-γ. Furthermore, changes in the oral microbiota were linked to worse RA conditions. Our study provides new insights into the bi-directional relationship between periodontitis and RA and suggest that monitoring the periodontal health of RA patients is particularly important.

Novel zafirlukast derivatives exhibit selective antibacterial activity against Porphyromonas gingivalis

Periodontal disease is an oral chronic immune-inflammatory disease highly prevalent worldwide that is initiated by specific oral bacterial species leading to local and systemic effects. The development of new preventive/therapeutic strategies to specifically target oral periodontopathogens without perturbing oral microbiome species normally colonizing the oral cavity is needed. The fast and affordable strategy of repositioning of already FDA-approved drugs can be an answer to the development of novel treatments against periodontal pathogens such as Porphyromonas gingivalis. Herein, we report the synthesis and antibacterial activity of novel zafirlukast derivatives, their bactericidal effect, and their cytotoxicity against oral epithelial cell lines. Many of these derivatives exhibited superior antibacterial activity against P. gingivalis compared to the parent drug zafirlukast. The most promising compounds were found to be selective against P. gingivalis and they were bactericidal in their activity. Finally, we demonstrated that these potent derivatives of zafirlukast provided a better safety profile against oral epithelial cells compared to zafirlukast.

There's no place like OM: Vesicular sorting and secretion of the peptidylarginine deiminase of Porphyromonas gingivalis

The oral pathogen Porphyromonas gingivalis is one of the major periodontal agents and it has been recently hailed as a potential cause of the autoimmune disease rheumatoid arthritis. In particular, the peptidylarginine deiminase enzyme of P. gingivalis (PPAD) has been implicated in the citrullination of certain host proteins and the subsequent appearance of antibodies against citrullinated proteins, which might play a role in the etiology of rheumatoid arthritis. The aim of this study was to investigate the extracellular localization of PPAD in a large panel of clinical P. gingivalis isolates. Here we show that all isolates produced PPAD. In most cases PPAD was abundantly present in secreted outer membrane vesicles (OMVs) that are massively produced by P. gingivalis, and to minor extent in a soluble secreted state. Interestingly, a small subset of clinical isolates showed drastically reduced levels of the OMV-bound PPAD and secreted most of this enzyme in the soluble state. The latter phenotype is strictly associated with a lysine residue at position 373 in PPAD, implicating the more common glutamine residue at this position in PPAD association with OMVs. Further, one isolate displayed severely restricted vesiculation. Together, our findings show for the first time that neither the major association of PPAD with vesicles, nor P. gingivalis vesiculation per se, are needed for P. gingivalis interactions with the human host.

Anti-rheumatic medication and salivary MMP-8, a biomarker for periodontal disease

OBJECTIVE

To investigate the impact of anti-rheumatic medications on salivary matrix metalloproteinase (MMP)-8 levels and MMP-8/TIMP (tissue inhibitor of MMPs)-1 ratio in patients with rheumatoid arthritis (RA) and periodontal findings during a 1-year follow-up.

MATERIALS AND METHODS

Salivary MMP-8 was measured by an immunofluorometric assay and TIMP-1 by an enzyme-linked immunosorbent assay of 53 patients with early untreated RA (ERA), naïve to synthetic disease modifying anti-rheumatic drugs (DMARDs), of 28 patients with chronic RA (CRA), candidates for biologic DMARDs and of 43 age- and sex-matched controls. Periodontal health was evaluated by bleeding on probing (BOP), pocket depth (PD), and periodontal inflammatory burden index (PIBI). Examinations were conducted twice for RA patients and once for controls.

RESULTS

Salivary MMP-8 level and MMP-8/TIMP-1 ratio associated positively with PIBI in patients with chronic RA (MMP-8: p < 0.001 at baseline, p = 0.002 after follow-up; MMP-8/TIMP-1 ratio p < 0.001, p = 0.003, respectively) and in controls (MMP-8: p = 0.010, MMP-8/TIMP-1 ratio: p = 0.010). Salivary MMP-8 levels were highest at the early stage of RA. The used DMARDs, synthetic or biologic, did not affect salivary MMP-8 concentrations.

CONCLUSIONS

The use of synthetic or biologic DMARDs did not affect salivary MMP-8 levels in RA patients regardless the duration of RA.

Dropping anchor: attachment of peptidylarginine deiminase via A-LPS to secreted outer membrane vesicles of Porphyromonas gingivalis

The periodontal pathogen Porphyromonas gingivalis has been invoked in the autoimmune disease rheumatoid arthritis (RA). This association relates to the peptidylarginine deiminase of P. gingivalis (PPAD), an enzyme capable of citrullinating human proteins and potentially contributing to loss of tolerance to citrullinated proteins in RA. PPAD is both retained in the outer membrane (OM) of P. gingivalis cells and secreted into the extracellular milieu, where it is detected in a soluble form and in association with outer membrane vesicles (OMVs). Recent studies showed that certain P. gingivalis proteins are retained in the OM through modification with an A-type lipopolysaccharide (A-LPS). Here, we investigated the possible involvement of A-LPS modification in the association of PPAD to the OM and OMVs. The results indicate that the OM- and OMV-associated PPAD is A-LPS-modified. The modified PPAD species is of low abundance in particular clinical isolates of P. gingivalis, which is not due to defects in the overall synthesis of A-LPS-modified proteins but, rather, to particular traits of the respective PPAD proteins. Lastly, we show that OMV association protects the A-LPS-modified PPAD from proteolytic degradation. Altogether, our observations show that A-LPS modification contributes to OM(V) sorting and ‘protective secretion’ of PPAD.

Human microbiome, infections, and rheumatic disease

Microbes have coevolved with their human hosts for millions of years and are vital to their normal development and homoeostasis. It is now clear that there is direct and indirect cross talk between the microbiome and host immune responses. However, the exact mechanisms for this microbial influence in disease pathogenesis remain elusive and are now a major research focus.

Autoimmune Profiling Reveals Peroxiredoxin 6 as a Candidate Traumatic Brain Injury Biomarker

Autoimmune profiling in rats revealed the antioxidant enzyme, peroxiredoxin 6 (PRDX6), as a target for autoantibodies evoked in response to traumatic brain injury (TBI). Consistent with this proposal, immunohistochemical analysis of rat cerebral cortex demonstrated that PRDX6 is highly expressed in the perivascular space, presumably contained within astrocytic foot processes. Accordingly, an immunosorbent electrochemiluminescence assay was developed for investigating PRDX6 in human samples. PRDX6 was found to be measurable in human blood and highly expressed in human cerebral cortex and platelets. Circulating levels of PRDX6 were elevated fourfold over control values 4 to 24 h following mild-to-moderate TBI. These findings suggest that PRDX6 may serve as a biomarker for TBI and that autoimmune profiling is a viable strategy for the discovery of novel TBI biomarkers.

Association between anti-Porphyromonas gingivalis or anti-α-enolase antibody and severity of periodontitis or rheumatoid arthritis (RA) disease activity in RA

Background

Periodontitis (PD) has been reported to be associated with rheumatoid arthritis (RA). Porphyromonas gingivalis (P. gingivalis) is a gram-negative anaerobic bacterium that is recognized as one of the major pathogenic organisms in PD and is the only bacterium known to express peptidylarginine deiminase (PAD). Antibody against human α-enolase (ENO1) is one of the autoantibodies in RA. ENO1 is a highly conserved protein, and could be a candidate molecule for molecular mimicry between bacterial and human proteins. In the present study, we measured serum antibody against P. gingivalis and human ENO1 in patients with RA and investigated their association with the severity of PD or disease activity of RA.

Methods

Two hundred, forty-eight patients with RA and 85 age- and sex-matched healthy controls were evaluated by rheumatologic and periodontal examinations. The serum levels of anti-P. gingivalis and anti-ENO1 antibodies were measured by an enzyme-linked immunosorbent assay (ELISA).

Results

Patients with RA had significantly higher levels of anti-P. gingivalis and anti-ENO1 antibody titers than the controls (p = 0.002 and 0.0001, respectively). Anti-P. gingivalis antibody titers significantly correlated with anti-ENO1 antibody titers in RA patients (r = 0.30, p < 0.0001). There were significant correlations between anti-P. gingivalis antibody titers and the gingival index (GI), probing pocket depth (PPD), bleeding on probing (BOP) and clinical attachment level (CAL) (p = 0.038, 0.004, 0.004 and 0.002, respectively) in RA. Anti-P. gingivalis antibody titers were not correlated with disease activity score 28 (DAS28) or anti-CCP titer. However, anti-ENO1 antibody titers were significantly correlated not only with the periodontal indices, such as PPD, BOP, and CAL (p = 0.013, 0.023 and 0.017, respectively), but also RA clinical characteristics, such as DAS28, anti-CCP titer, and ESR (p = 0.009, 0.015 and 0.001, respectively).

Conclusion

Anti-P. gingivalis and anti-ENO1 antibody titers were correlated with the severity of PD in RA. Anti-ENO1 antibody titers, but not anti-P. gingivalis antibody titers, were further associated with RA disease activity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-015-0647-6) contains supplementary material, which is available to authorized users.

Increased Eotaxin and MCP-1 Levels in Serum from Individuals with Periodontitis and in Human Gingival Fibroblasts Exposed to Pro-Inflammatory Cytokines

Periodontitis is a chronic inflammatory disease of tooth supporting tissues resulting in periodontal tissue destruction, which may ultimately lead to tooth loss. The disease is characterized by continuous leukocyte infiltration, likely mediated by local chemokine production but the pathogenic mechanisms are not fully elucidated. There are no reliable serologic biomarkers for the diagnosis of periodontitis, which is today based solely on the degree of local tissue destruction, and there is no available biological treatment tool. Prompted by the increasing interest in periodontitis and systemic inflammatory mediators we mapped serum cytokine and chemokine levels from periodontitis subjects and healthy controls. We used multivariate partial least squares (PLS) modeling and identified monocyte chemoattractant protein-1 (MCP-1) and eotaxin as clearly associated with periodontitis along with C-reactive protein (CRP), years of smoking and age, whereas the number of remaining teeth was associated with being healthy. Moreover, body mass index correlated significantly with serum MCP-1 and CRP, but not with eotaxin. We detected higher MCP-1 protein levels in inflamed gingival connective tissue compared to healthy but the eotaxin levels were undetectable. Primary human gingival fibroblasts displayed strongly increased expression of MCP-1 and eotaxin mRNA and protein when challenged with tumor necrosis factor-α (TNF-α and interleukin-1β (IL-1β), key mediators of periodontal inflammation. We also demonstrated that the upregulated chemokine expression was dependent on the NF-κΒ pathway. In summary, we identify higher levels of CRP, eotaxin and MCP-1 in serum of periodontitis patients. This, together with our finding that both CRP and MCP-1 correlates with BMI points towards an increased systemic inflammatory load in patients with periodontitis and high BMI. Targeting eotaxin and MCP-1 in periodontitis may result in reduced leukocyte infiltration and inflammation in periodontitis and maybe prevent tooth loss.

Neutrophil extracellular traps as a new paradigm in innate immunity: friend or foe?

The discovery of neutrophil extracellular traps in 2004 opened a fascinating new chapter in immune-mediated microbial killing. Brinkman et al. demonstrated that neutrophils, when catastrophically stimulated, undergo a novel form of programmed cell death (neutrophil extracellular trap formation) whereby they decondense their entire nuclear chromatin/DNA and release the resulting structure into the cytoplasm to mix with granule-derived antimicrobial peptides before extruding these web-like structures into the extracellular environment. The process requires the activation of the granule enzyme peptidyl arginine deiminase-4, the formation of reactive oxygen species (in particular hypochlorous acid), the neutrophil microtubular system and the actin cytoskeleton. Recent work by Yousefi et al. demonstrated that exposure to different agents for shorter stimulation periods resulted in neutrophil extracellular trap release from viable granulocytes, and that such neutrophil extracellular traps comprised mitochondrial DNA rather than nuclear DNA and were also capable of microbial entrapment and destruction. Deficiency in NADPH-oxidase production (as found in patients with chronic granulomatous disease) results in an inability to produce neutrophil extracellular traps and, along with their failure to produce antimicrobial reactive oxygen species, these patients suffer from severe, and sometimes life-threatening, infections. However, conversely the release of nuclear chromatin into tissues is also potentially autoimmunogenic and is now associated with the generation of anti-citrullinated protein antibodies in seropositive rheumatoid arthritis. Other neutrophil-derived nuclear and cytoplasmic contents are also pathogenic, either through direct effects on tissues or via autoimmune processes (e.g. autoimmune vasculitis). In this review, we discuss the plant origins of a highly conserved innate immune method of microbial killing, the history and biology of neutrophil extracellular traps and their role in defence and in human diseases. We attempt to resolve areas of controversy and propose roles for excess neutrophil extracellular trap release from hyperactive/reactive neutrophils and for the unique peptidyl arginine deiminase enzyme of Porphyromonas gingivalis in the pathogenesis of periodontitis, and subsequently a role for periodontitis/the peptidyl arginine deiminase enzyme of P. gingivalis in the causal pathway of autoimmune diseases such as rheumatoid arthritis. We propose that neutrophil extracellular trap and peptidyl arginine deiminase release may propagate tissue-destructive mechanisms rather than provide protection in susceptible individuals and that release of host-derived DNase may play an important role in the digestion and removal of neutrophil extracellular traps within tissues.

Autoimmune correlation of rheumatoid arthritis and periodontitis

Rheumatoid arthritis and periodontitis, both, chronic inflammatory diseases share certain common diagnostic, pathological, immunogenetic and therapeutic features. A recently discovered enzymatic mimicry between human and bacterial species is novel and it opens up a new terrain for therapeutic blockade in the management of rheumatoid arthritis.

Periodontitis and etanercept discontinuation risk in anti-tumor necrosis factor-naive rheumatoid arthritis patients: a nationwide population-based cohort study

OBJECTIVE

The objective of this study was to investigate the association between periodontitis (PD) and etanercept (ETN) discontinuation in anti-tumor necrosis factor (anti-TNF)-naive patients with rheumatoid arthritis (RA).

METHODS

This retrospective nationwide population-based cohort study identified 3359 anti-TNF-naive patients with RA (age at diagnosis ≥16 years) in whom ETN treatment was initiated using administrative data. We identified PD exposure within 5 years before ETN initiation and during ETN treatment. Cox proportional hazard models were used to assess ETN discontinuation risk associated with PD within 5 years before ETN initiation, shown as hazard ratios with 95% confidence intervals (CIs). Stratified analyses were performed on the basis of PD during ETN treatment to avoid violating the Cox regression assumptions.

RESULTS

Patients with PD history during the 5 years before ENT initiation had a higher risk of ETN discontinuation compared with those without such history; the hazard ratios of ETN discontinuation were 1.27 (95% CI, 1.01-1.60) and 1.17 (95% CI, 1.06-1.30) among patients with and without PD during ETN treatment, respectively. Other risk factors included age older than 65 years and daily prednisolone dose greater than 10 mg/d within 1 year before ETN initiation. Concomitant methotrexate, leflunomide, salazopyrin, or hydroxychloroquine administration had a protective effect on ETN discontinuation in patients without PD during ETN treatment, but the protective effect by leflunomide, salazopyrin, and hydroxychloroquine was attenuated in patients with PD during ETN treatment (P for interaction <0.05).

CONCLUSIONS

A PD history within 5 years before ETN administration was associated with increased ETN discontinuation risk in anti-TNF-naive patients with RA.

Citrullination and proteolytic processing of chemokines by Porphyromonas gingivalis

The outgrowth of Porphyromonas gingivalis within the inflammatory subgingival plaque is associated with periodontitis characterized by periodontal tissue destruction, loss of alveolar bone, periodontal pocket formation, and eventually, tooth loss. Potential virulence factors of P. gingivalis are peptidylarginine deiminase (PPAD), an enzyme modifying free or peptide-bound arginine to citrulline, and the bacterial proteases referred to as gingipains (Rgp and Kgp). Chemokines attract leukocytes during inflammation. However, posttranslational modification (PTM) of chemokines by proteases or human peptidylarginine deiminases may alter their biological activities. Since chemokine processing may be important in microbial defense mechanisms, we investigated whether PTM of chemokines by P. gingivalis enzymes occurs. Upon incubation of interleukin-8 (IL-8; CXCL8) with PPAD, only minor enzymatic citrullination was detected. In contrast, Rgp rapidly cleaved CXCL8 in vitro. Subsequently, different P. gingivalis strains were incubated with the chemokine CXCL8 or CXCL10 and their PTMs were investigated. No significant CXCL8 citrullination was detected for the tested strains. Interestingly, although considerable differences in the efficiency of CXCL8 degradation were observed with full cultures of various strains, similar rates of chemokine proteolysis were exerted by cell-free culture supernatants. Sequencing of CXCL8 incubated with supernatant or bacteria showed that CXCL8 is processed into its more potent forms consisting of amino acids 6 to 77 and amino acids 9 to 77 (the 6-77 and 9-77 forms, respectively). In contrast, CXCL10 was entirely and rapidly degraded by P. gingivalis, with no transient chemokine forms being observed. In conclusion, this study demonstrates PTM of CXCL8 and CXCL10 by gingipains of P. gingivalis and that strain differences may particularly affect the activity of these bacterial membrane-associated proteases.

Chronic exposure to oral pathogens and autoimmune reactivity in acute coronary atherothrombosis

Background. It has been hypothesized that various infective agents may activate immune reactions as part of the atherosclerotic process. We aimed to investigate the interrelationship between chronic exposure to oral pathogens and immune-inflammatory response in patients with acute coronary atherothrombosis. Patients and Methods. The study included 200 participants from Serbia: 100 patients with acute myocardial infarction (MI), and 100 age- and sex-matched controls. Antibodies to oral anaerobes and aerobes were determined as well as autoantibodies to endothelial cells, beta-2 glycoprotein I, platelet glycoprotein IIb/IIIa and anticardiolipin. Interleukin-6 (IL-6) and C-reactive protein (CRP) were measured. Results. The mean serum antibodies to oral anaerobes tended to be higher among subjects with MI (0.876 ± 0.303 versus 0.685 ± 0.172 OD, P < 0.001). Similarly, antibody levels against oral aerobes in patients were significantly different from controls. Antibodies against endothelial cell, beta-2 glycoprotein I, platelet glycoprotein IIb/IIIa, anticardiolipin along with CRP and IL-6 were highly elevated in patients. The levels of antibodies to oral bacteria showed linear correlation with tissue antibodies, CRP and IL-6. Conclusion. Antibody response to chronic oral bacterial infections and host immune response against them may be responsible for the elevation of tissue antibodies and biomarkers of inflammation which are involved in acute coronary thrombosis development.

A Potential Link between Environmental Triggers and Autoimmunity

Autoimmune diseases have registered an alarming rise worldwide in recent years. Accumulated evidence indicates that the immune system's ability to distinguish self from nonself is negatively impacted by genetic factors and environmental triggers. Genetics is certainly a factor, but since it normally takes a very long time for the human genetic pattern to change enough to register on a worldwide scale, increasingly the attention of studies has been focused on the environmental factors of a rapidly changing and evolving civilization. New technology, new industries, new inventions, new chemicals and drugs, and new foods and diets are constantly and rapidly being introduced in this fast-paced ever-changing world. Toxicants, infections, epitope spreading, dysfunctions of immune homeostasis, and dietary components can all have an impact on the body's delicate immune recognition system. Although the precise etiology and pathogenesis of many autoimmune diseases are still unknown, it would appear from the collated studies that there are common mechanisms in the immunopathogenesis of multiple autoimmune reactivities. Of particular interest is the citrullination of host proteins and their conversion to autoantigens by the aforementioned environmental triggers. The identification of these specific triggers of autoimmune reactivity is essential then for the development of new therapies for autoimmune diseases.

Residual Salivary Secretion Ability May Be a Useful Marker for Differential Diagnosis in Autoimmune Diseases

Background. We have elucidated decreased resting salivary flow in approximately 60% of patients with autoimmune diseases not complicated by Sjögren syndrome (SjS). In this study, salivary stimulation tests using capsaicin were performed to examine residual salivary secretion ability in patients with autoimmune diseases. Materials and Methods. Fifty-eight patients were divided into three groups: patients with primary or secondary SjS (SjS group), patients with systemic sclerosis not complicated by SjS (SSc group), and patients with other autoimmune diseases (non-SjS/non-SSc group). Simple filter paper and filter paper containing capsaicin were used to evaluate salivary flow rates. Results. Resting salivary flow rates were significantly lower in the SjS and SSc groups than in the non-SjS/non-SSc group but did not differ significantly between the SjS and SSc groups. Capsaicin-stimulated salivary flow rates were significantly lower in the SjS and SSc groups than in the non-SjS/non-SSc group, but not significantly different between the SjS and SSc groups. In the non-SjS/non-SSc group, salivary flow rates increased after capsaicin stimulation to the threshold level for determination of salivary gland dysfunction, whereas no improvement was observed in the SjS and SSc groups. Conclusion. Residual salivary secretion ability may be a useful marker for differential diagnosis in autoimmune diseases.

Expression of Porphyromonas gingivalis small RNA in response to hemin availability identified using microarray and RNA-seq analysis

There is a significant body of work suggesting that sRNA-mediated post-transcriptional regulation is a conserved mechanism among pathogenic bacteria to modulate bacterial virulence and survival. Porphyromonas gingivalis is recognized as an etiological agent of periodontitis and implicated in contributing to the development of multiple inflammatory diseases including cardiovascular disease. Using NimbleGen microarray analysis and a strand-specific method to sequence cDNA libraries of small RNA-enriched P. gingivalis transcripts using Illumina's high-throughput sequencing technology, we identified putative sRNA and generated sRNA expression profiles in response to growth phase, hemin availability after hemin starvation, or both. We identified transcripts that mapped to intergenic sequences as well as antisense transcripts that mapped to open reading frames of the annotated genome. Overall, this approach provided a comprehensive way to survey transcriptional activity to discover functionally linked RNA transcripts, responding to specific environmental cues, that merit further investigation.

Periodontal disease and rheumatoid arthritis: the evidence accumulates for complex pathobiologic interactions

PURPOSE OF REVIEW

This review was conducted to focus on the recent clinical and translational research related to the associations between periodontal disease and rheumatoid arthritis.

RECENT FINDINGS

There is a growing interest in the associations between oral health and autoimmune and inflammatory diseases. A number of epidemiologic studies have described associations between rheumatoid arthritis and periodontal disease. Recent clinical studies continue to support these reports, and are increasingly linked with biological assessments to better understand the nature of these relationships. A number of recent studies have evaluated the periopathogenic roles of Porphyromonas gingivalis, the oral microbiome, and mechanisms of site-specific and substrate-specific citrullination. These are helping to further elucidate the interactions between these two inflammatory disease processes.

SUMMARY

Studies of clinical oral health parameters, the gingival microenvironment, autoantibodies and biomarkers, and rheumatoid arthritis disease activity measures are providing a better understanding of the potential mechanisms responsible for rheumatoid arthritis and periodontal disease associations. The cumulative results and ongoing studies have the promise to identify novel mechanisms and interventional strategies to improve patient outcomes for both conditions.

Porphyromonas gingivalis facilitates the development and progression of destructive arthritis through its unique bacterial peptidylarginine deiminase (PAD)

Rheumatoid arthritis and periodontitis are two prevalent chronic inflammatory diseases in humans and are associated with each other both clinically and epidemiologically. Recent findings suggest a causative link between periodontal infection and rheumatoid arthritis via bacteria-dependent induction of a pathogenic autoimmune response to citrullinated epitopes. Here we showed that infection with viable periodontal pathogen Porphyromonas gingivalis strain W83 exacerbated collagen-induced arthritis (CIA) in a mouse model, as manifested by earlier onset, accelerated progression and enhanced severity of the disease, including significantly increased bone and cartilage destruction. The ability of P. gingivalis to augment CIA was dependent on the expression of a unique P. gingivalis peptidylarginine deiminase (PPAD), which converts arginine residues in proteins to citrulline. Infection with wild type P. gingivalis was responsible for significantly increased levels of autoantibodies to collagen type II and citrullinated epitopes as a PPAD-null mutant did not elicit similar host response. High level of citrullinated proteins was also detected at the site of infection with wild-type P. gingivalis. Together, these results suggest bacterial PAD as the mechanistic link between P. gingivalis periodontal infection and rheumatoid arthritis.

Clinical and epidemiological data indicates that chronic periodontal disease (PD), one of the most prevalent infectious inflammatory disease of mankind, is linked to systemic inflammatory diseases such as cardiovascular diseases (CVD), rheumatoid arthritis (RA) and chronic obstructive pulmonary disease (COPD). Nevertheless, the causative mechanisms of association between PD and chronic inflammatory diseases are very poorly understood. Recent findings suggest a causative link between periodontal infection and rheumatoid arthritis via bacteria-dependent induction of a pathogenic response to citrullinated epitopes. In present study we show that infection with viable periodontal pathogen Porphyromonas gingivalis but not another oral bacterium (Prevotella intermedia), exacerbated CIA, as manifested by earlier onset, accelerated progression and enhanced severity of the disease, including significantly increased bone and cartilage destruction. The ability of P. gingivalis to augment CIA was dependent on the expression of a unique enzyme peptidylarginine deiminase, which converts arginine residues in proteins to citrulline. This knowledge may create new perspectives in the treatment and prevention of RA in susceptible individuals.

Lessons to be learned from periodontitis

PURPOSE OF REVIEW

This article reviews the link between periodontitis and rheumatoid arthritis (RA) with regard to similarities in genetic risk factors and immunopathogenesis. Emphasis is paid to the potential role of the periodontal pathogen Porphyromonas gingivalis in the etiopathogenesis of both periodontitis and RA, in particular by post-translational modification of arginine into citrulline.

RECENT FINDINGS

P. gingivalis, a major periodontal pathogen, is presently known as the only bacterium in the oral flora which contains a peptidyl arginine deiminase enzyme (PAD). This enzyme is necessary for citrullination. As a result, citrullinated proteins and P. gingivalis PAD, PAD2 and PAD4 (expressed by infiltrating neutrophils) are found in periodontal tissues. Autoantibodies directed to citrullinated proteins, so-called anticitrullinated protein antibodies (ACPAs), are found to be present in gingival crevicular fluid originating from inflamed gingival tissue. Furthermore, treatment studies have revealed that nonsurgical periodontal treatment, that is removal of sub-gingival calculus and biofilm deposits, is accompanied by a reduction in the severity of RA.

SUMMARY

In this study the similarities in immune response and tissue degradation between RA and periodontitis are reviewed. It is shown that the two diseases share the same environmental and genetic risk factors, apart from the fact that there is a link between both diseases via citrullination of proteins by human PAD and P. gingivalis PAD.

Effect of periodontal treatment on the clinical parameters of patients with rheumatoid arthritis: study protocol of the randomized, controlled ESPERA trial

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory disorder that leads to joint damage, deformity, and pain. It affects approximately 1% of adults in developed countries. Periodontitis is a chronic oral infection, caused by inflammatory reactions to gram-negative anaerobic bacteria, and affecting about 35 to 50% of adults. If left untreated, periodontitis can lead to tooth loss. A significant association has been shown to exist between periodontitis and RA in observational studies. Some intervention studies have suggested that periodontal treatment can reduce serum inflammatory biomarkers such as C-reactive protein, or erythrocyte sedimentation rate. We hypothesize that periodontitis could be an aggravating factor in patients with RA, and that its treatment would improve RA outcomes. The aim of this clinical trial is to assess the effect of periodontal treatment on the biological and clinical parameters of patients with RA.

METHODS/DESIGN

The ESPERA (Experimental Study of Periodontitis and Rheumatoid Arthritis) study is an open-label, randomized, controlled trial. Subjects with both RA and periodontitis will be recruited at two university hospitals in southwestern France. In total, 40 subjects will be randomized into two arms (intervention and control groups), and will be followed up for 3 months. Intervention will consist of full-mouth supra-gingival and sub-gingival non-surgical scaling and root planing, followed by systemic antibiotic therapy, local antiseptics, and oral hygiene instructions. After the 3-month follow-up period, the same intervention will be applied to the subjects randomized to the control group.The primary outcome will be change of in Disease Activity Score in 28 Joints (DAS28) at the end of the follow-up period. Secondary outcomes will be the percentages of subjects with 20%, 50%, and 70% improvement in disease according to the American College of Rheumatology criteria. Health-related quality of life assessments (the Health Assessment Questionnaire and the Geriatric Oral Health Assessment Index) will also be compared between the two groups.

DISCUSSION

Evidence-based management of potential aggravating factors in subjects with active RA could be of clinical importance, yet there are few randomized controlled trials on the effect of periodontal treatment on the clinical parameters of RA. The ESPERA trial is designed to determine if non-surgical periodontal treatment could improve clinical outcomes in patients with active RA, and the quality of life of these patients.

TRIAL REGISTRATION

The ESPERA Trial was registered in Current Controlled Trials [ISRCTN79186420] on 2012/03/20. The trial started recruiting on 2012/03/06.

The role of the microbiome in rheumatic diseases

There is a growing understanding of the mechanisms by which the influence of the microbiota projects beyond sites of primary mucosal occupation to other human body systems. Bacteria present in the intestinal tract exert a profound effect on the host immune system, both locally and at distant sites. The oral cavity has its own characteristic microbiota, which concentrates in periodontal tissues and is in close association with a permeable epithelium. In this review we examine evidence which supports a role for the microbiome in the aetiology of rheumatic disease. We also discuss how changes in the composition of the microbiota, particularly within the gastrointestinal tract, may be affected by genetics, diet, and use of antimicrobial agents. Evidence is presented to support the theory that an altered microbiota is a factor in the initiation and perpetuation of inflammatory diseases, including rheumatoid arthritis (RA), spondyloarthritis (SpA), and inflammatory bowel disease (IBD). Mechanisms through which the microbiota may be involved in the pathogenesis of these diseases include altered epithelial and mucosal permeability, loss of immune tolerance to components of the indigenous microbiota, and trafficking of both activated immune cells and antigenic material to the joints. The potential to manipulate the microbiome, by application of probiotics and faecal microbial transplant (FMT), is now being investigated. Both approaches are in their infancy with regard to management of rheumatic disease but their potential is worthy of consideration, given the need for novel therapeutic approaches, and the emerging recognition of the importance of microbial interactions with human hosts.

Hyposalivation in autoimmune diseases

We have investigated the prevalence of dry mouth among patients with autoimmune diseases other than Sjögren's syndrome. One hundred and forty-four patients, excluding patients with primary Sjögren's syndrome, were enrolled in this study. The volume of saliva secreted was measured with the screening technique for estimation of salivary flow, which uses a filter paper for diagnosing dry mouth. Disturbed salivary secretion was observed in 84 (58.3 %) of the 144 patients. In the case of patients free of Sjögren's syndrome, the prevalence of disturbed salivary secretion differed significantly among the disease groups (P < 0.05), with the prevalence being over 50 % in all disease groups other than the rheumatoid arthritis group and the highest in the systemic sclerosis group. There was significant positive correlation between the number of colored spots and oral visual analog scale score (r = 0.45, P < 0.0001). Autoimmune diseases can be accompanied by salivary gland dysfunction, regardless of the presence/absence of complication by Sjögren's syndrome. In the present study, the screening technique for estimation of salivary flow, which uses a filter paper for diagnosing dry mouth, was shown to be a useful means of detecting salivary gland dysfunction.

Effects of periodontal therapy on disease activity and systemic inflammation in rheumatoid arthritis patients

OBJECTIVE

This observational prospective cohort study aimed to evaluate the effects of non-surgical periodontal treatment on clinical periodontal measurements and systemic inflammatory mediator levels in low or moderate to highly active rheumatoid arthritis (RA) patients with chronic periodontitis.

SUBJECTS AND METHODS

Rheumatoid arthritis activity was assessed with disease activity score test (DAS28). Thirty patients with RA with moderate to high disease activity (DAS28 ≥ 3.2) and chronic periodontitis (MHDA group) and thirty patients with RA with low disease activity (DAS28 < 3.2) and chronic periodontitis (LDA group) were enrolled in the study. The patients were monitored at the beginning and 3 months after undergoing periodontal therapy. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), tumour necrosis factor-alpha (TNF-α) levels in serum, DAS28 and periodontal parameters were evaluated.

RESULTS

Erythrocyte sedimentation rate, CRP, TNF-α levels in serum, DAS28 and periodontal parameters exhibited similar and significant reduction 3 months after the non-surgical periodontal treatment.

CONCLUSION

Non-surgical periodontal treatment may prove beneficial in reducing RA severity as measured by ESR, CRP, TNF-α levels in serum and DAS28 in low or moderate to highly active RA patients with chronic periodontitis.

Of bugs and joints: the relationship between infection and joints

The association between microbes and joints has existed since antiquity, and remains complex. Diagnosis is often times difficult to determine despite highly suspicious clinical characteristics for the presence of an underlying infection. Over the several past decades, considerable advances have occurred in diagnostic methodologies and therapy. However, the morbidity and mortality of septic arthritis remains high. Great advances have occurred in the diagnosis, pathogenesis, and therapeutic management of reactive arthritis, and there is evidence that when the responsible microorganism is Chlamydia trachomathis, complete remission and cure is possible. Emergent infections, especially viral, has been recognized, i.e. HIV, hepatitis C, and most recently Chikengunya virus, and in the case of HIV associated articular manifestations, the introduction of HAART has resulted in a decrease in the incidence and development of newer complications such as the immune reconstitution syndrome. The infectious etiology of rheumatoid arthritis is being strongly considered once again, and the exciting association with periodontal disease is at the forefront of intense research. The gut microbiota is also being investigated and new and most interesting data is being gathered of the potential role of commensal gut organisms and the pathogenesis of rheumatoid arthritis.

Association between a history of periodontitis and the risk of rheumatoid arthritis: a nationwide, population-based, case-control study

OBJECTIVE

To investigate the association between the risk of rheumatoid arthritis (RA) and a history of periodontitis.

METHODS

This nationwide, population-based, case-control study used administrative data to identify 13 779 newly diagnosed patients with RA (age ≥16 years) as the study group and 137 790 non-patients with RA matched for age, sex, and initial diagnosis date (index date) as controls. Using conditional logistic regression analysis after adjustment for potential confounders, including geographical region and a history of diabetes and Sjögren's syndrome, ORs with 95% CI were calculated to quantify the association between RA and periodontitis. To evaluate the effects of periodontitis severity and the lag time since the last periodontitis visit on RA development, ORs were calculated for subgroups of patients with periodontitis according to the number of visits, cumulative cost, periodontal surgery and time interval between the last periodontitis-related visit and the index date.

RESULTS

An association was found between a history of periodontitis and newly diagnosed RA (OR=1.16; 95% CI 1.13 to 1.21). The strength of this association remained statistically significant after adjustment for potential confounders (OR=1.16; 95% CI 1.12 to 1.20), and after variation of periodontitis definitions. The association was dose- and time-dependent and was strongest when the interval between the last periodontitis-related visit and the index date was <3 months (OR=1.64; 95% CI 1.49 to 1.79).

CONCLUSIONS

This study demonstrates an association between periodontitis and incident RA. This association is weak and limited to lack of individual smoking status.

Highly specific protease-based approach for detection of porphyromonas gingivalis in diagnosis of periodontitis

Porphyromonas gingivalis is associated with the development of periodontitis. Here we describe the development of a highly specific protease-based diagnostic method for the detection of P. gingivalis in gingival crevicular fluid. Screening of a proteolytic peptide substrate library, including fluorogenic dipeptides that contain d-amino acids, led to the discovery of five P. gingivalis-specific substrates. Due to the presence of lysine and arginine residues in these substrates, it was hypothesized that the cleavage was mediated by the gingipains, a group of P. gingivalis-specific proteases. This hypothesis was confirmed by the observation that P. gingivalis gingipain knockout strains demonstrated clearly impaired substrate cleavage efficacy. Further, proteolytic activity on the substrates was increased by the addition of the gingipain stimulators dithiothreitol and l-cysteine and decreased by the inhibitors leupeptin and N-ethylmaleimide. Screening of saliva and gingival crevicular fluid of periodontitis patients and healthy controls showed the potential of the substrates to diagnose the presence of P. gingivalis proteases. By using paper points, a sensitivity of approximately 10(5) CFU/ml was achieved. P. gingivalis-reactive substrates fully composed of l-amino acids and Bz-l-Arg-NHPhNO(2) showed a relatively low specificity (44 to 85%). However, the five P. gingivalis-specific substrates that each contained a single d-amino acid showed high specificity (96 to 100%). This observation underlines the importance of the presence of d-amino acids in substrates used for the detection of bacterial proteases. We envisage that these substrates may improve the specificity of the current enzyme-based diagnosis of periodontitis associated with P. gingivalis.