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

Porphyromonas gingivalis, a bridge between oral health and immune evasion in gastric cancer

Porphyromonas gingivalis (P. gingivalis) is a gram-negative oral pathogen associated with chronic periodontitis. Previous studies have linked poor oral health and periodontitis with oral cancer. Severe cases of periodontal disease can result in advanced periodontitis, leading to tissue degradation, tooth loss, and may also correlate with higher gastric cancer (GC) risk. In fact, tooth loss is associated with an elevated risk of cancer. However, the clinical evidence for this association remains inconclusive. Periodontitis is also characterized by chronic inflammation and upregulation of members of the Programmed Death 1/PD1 Ligand 1 (PD1/PDL1) axis that leads to an immunosuppressive state. Given that chronic inflammation and immunosuppression are conditions that facilitate cancer progression and carcinogenesis, we hypothesize that oral P. gingivalis and/or its virulence factors serve as a mechanistic link between oral health and gastric carcinogenesis/GC progression. We also discuss the potential impact of P. gingivalis' virulence factors (gingipains, lipopolysaccharide (LPS), and fimbriae) on inflammation and the response to immune checkpoint inhibitors in GC which are part of the current standard of care for advanced stage patients.

Associations between periodontitis and serum anti-malondialdehyde-acetaldehyde antibody concentrations in rheumatoid arthritis: A case-control study

BACKGROUND

Malondialdehyde-acetaldehyde (MAA) adducts lead to generation of anti-MAA autoantibodies and have been independently identified in inflamed periodontal and rheumatoid arthritis (RA) tissues. This study evaluates serum samples from RA cases and osteoarthritis (OA) controls to quantify associations between periodontal clinical measures, alveolar bone loss (ABL), and anti-Porphyromonas gingivalis, anti-Prevotella intermedia, and anti-Fusobacterium nucleatum antibody concentrations with anti-MAA antibody concentrations.

METHODS

Participants (n = 284 RA cases, n = 330 OA controls) underwent periodontal clinical assessments and ABL measurements. Serum immunoglobulin (Ig) A, IgG, and IgM anti-MAA and serum IgG antibacterial antibody concentrations were quantified by enzyme-linked immunosorbent assay (ELISA). Analyses utilized simple linear regression and multivariable adjusted models.

RESULTS

No significant associations of periodontal clinical measures with serum anti-MAA were found. Moderate (p = 0.038 and p = 0.036, respectively) and high ABL (p = 0.012 and p = 0.014, respectively) in RA cases (but not in OA) were positively associated with IgG and IgM anti-MAA. Anti-P. gingivalis and anti-P. intermedia antibody concentrations were positively associated with IgA (p = 0.001 for both), IgG (p = 0.007 and p = 0.034, respectively), and IgM anti-MAA antibody concentrations (p < 0.001 and p = 0.020, respectively), while anti-F. nucleatum was positively associated with IgG anti-MAA (p = 0.042), findings that were similar across groups.

CONCLUSIONS

A positive association was demonstrated between ABL and serum IgG and IgM anti-MAA antibody concentrations that was unique to RA and not observed in OA. Serum anti-P. gingivalis, anti-P. intermedia, and anti-F. nucleatum antibody concentrations displayed significant associations with anti-MAA antibody in both groups. These findings suggest MAA may play a role in the interrelationship between the periodontium and RA.

A Bibliometric Analysis of Literature on the Impact of Rheumatoid Arthritis on Oral Health (1987-2024)

This bibliometric analysis investigates the research landscape concerning the impact of rheumatoid arthritis (RA) on oral health through a comprehensive literature review. The study includes all English-language articles retrieved from the PubMed database, focusing on the relationship between RA and various aspects of oral health without any filter. The analysis of 261 publications revealed fluctuations in publication patterns from 1987 to 2024, with notable surges and declines in research activity. Collaborative networks among authors and institutions were identified, highlighting key contributors and prolific institutions such as Karolinska Institutet. The themes prevalent in the research included demographics, oral microbiota, biomarkers, treatment outcomes, and molecular mechanisms. Trend topic and thematic evolution analyses elucidated shifts in research focus from traditional concerns to emerging areas such as oral microbiology and immunological mechanisms. Key findings underscored the need for more clinical trials to comprehend the impact of RA on oral health, enhanced interdisciplinary collaboration, exploration of emerging areas, and longitudinal studies. This analysis provides valuable insights into the evolving research landscape, informing future investigations and interventions to improve oral health outcomes in individuals with RA.

Association between rheumatoid arthritis and pulpal-periapical pathology: a systematic review

OBJECTIVES

Rheumatoid arthritis (RA) is a debilitating disease where numerous pro-inflammatory cytokines have a proven role in its pathology. These cytokines are also involved in the pathogenesis of apical periodontitis (AP) where they have a pro-inflammatory role and induce bone resorption. Patients with RA may therefore be more prone to develop pulpal-periapical pathology (PPP). This study systematically reviewed the existing literature evaluating the association between RA and PPP.

MATERIALS AND METHODS

Studies including human participants with both RA and PPP were included. The search was performed in PubMed, Web of Science, and The Cochrane Library databases using keywords and Medical Subject Headings (MeSH) search terms. The risk of bias was assessed using Newcastle-Ottawa Quality Assessment Scale. The following parameters were extracted and analyzed by the reviewers; author, journal, year, design of the study, diagnostic criteria for periapical pathology, the association between rheumatoid arthritis and periapical pathology, and the evidence level.

RESULTS

The search identified 142 records. Inclusion criteria were as follows; studies in the English language, including human participants only, including patients with RA and PPP, cohort studies, cross-sectional studies, clinical trials, and case-control studies. According to the inclusion criteria, 5 studies were included in this systematic review. Three of the five studies reported significant association between RA and PPP.

CONCLUSIONS

Existing evidence suggests there may be an association between RA and PPP.

CLINICAL RELEVANCE

Clinicians should be aware that RA patients can be more prone to develop PPP which may result in a reduced quality of life.

Smoking, Serum Albumin and 25-hydroxy Vitamin D Levels, and Bone Mineral Density Are Associated with Tooth Loss in Patients with Rheumatoid Arthritis

Objectives This study investigated factors associated with tooth loss in patients with rheumatoid arthritis (RA). Methods A total of 429 patients with RA were enrolled in the study. We examined tooth loss and clinical data. Patients were classified into two groups: a group with tooth loss (tooth loss-positive group), and a group without tooth loss (tooth loss-negative group). Patients were included in the tooth loss-positive group if they had fewer remaining teeth than the number defined by the Ministry of Health, Labour and Welfare in Japan to be the normal number teeth for that age and sex. Factors associated with tooth loss were analyzed by comparing the tooth loss-positive and loss-negative groups. Results The frequency of patients with tooth loss was 39.6%. The factors associated with tooth loss were smoking [odds ratio (OR) 1.638; 95% confidence interval (CI) 1.165-2.302], serum levels of albumin (OR 0.325; 95% CI 0.149-0.707) and 25-hydroxy vitamin D (OR 0.947; 95% CI 0.915-0.980), and total hip T score (OR 0.713; 95% CI 0.535-0.950). Conclusion This study revealed that tooth loss is associated with smoking, serum levels of albumin and 25-hydroxy vitamin D, and the total hip T score in patients with RA. Our findings may help prevent tooth loss in patients with RA.

Root Canal Infection and Its Impact on the Oral Cavity Microenvironment in the Context of Immune System Disorders in Selected Diseases: A Narrative Review

The oral cavity has a specific microenvironment, and structures such as teeth are constantly exposed to chemical and biological factors. Although the structure of the teeth is permanent, due to exposure of the pulp and root canal system, trauma can have severe consequences and cause the development of local inflammation caused by external and opportunistic pathogens. Long-term inflammation can affect not only the local pulp and periodontal tissues but also the functioning of the immune system, which can trigger a systemic reaction. This literature review presents the current knowledge on root canal infections and their impact on the oral microenvironment in the context of immune system disorders in selected diseases. The result of the analysis of the literature is the statement that periodontal-disease-caused inflammation in the oral cavity may affect the development and progression of autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, or Sjogren's syndrome, as well as affecting the faster progression of conditions in which inflammation occurs such as, among others, chronic kidney disease or inflammatory bowel disease.

Serum antibodies to periodontal pathogens prior to rheumatoid arthritis diagnosis: A case-control study

OBJECTIVES

1) To quantify the association between anti-Porphyromonas gingivalis serum antibody concentrations and the risk of developing rheumatoid arthritis (RA), and 2) to quantify the associations among RA cases between anti-P. gingivalis serum antibody concentrations and RA-specific autoantibodies. Additional anti-bacterial antibodies evaluated included anti-Fusobacterium nucleatum and anti-Prevotella intermedia.

METHODS

Serum samples were acquired pre- and post- RA diagnosis from the U.S. Department of Defense Serum Repository (n = 214 cases, 210 matched controls). Using separate mixed-models, the timing of elevations of anti-P. gingivalis, anti-P. intermedia, and anti-F. nucleatum antibody concentrations relative to RA diagnosis were compared in RA cases versus controls. Associations were determined between serum anti-CCP2, ACPA fine specificities (vimentin, histone, and alpha-enolase), and IgA, IgG, and IgM RF in pre-RA diagnosis samples and anti-bacterial antibodies using mixed-effects linear regression models.

RESULTS

No compelling evidence of case-control divergence in serum anti-P. gingivalis, anti-F. nucleatum, and anti-P. intermedia was observed. Among RA cases, including all pre-diagnosis serum samples, anti-P. intermedia was significantly positively associated with anti-CCP2, ACPA fine specificities targeting vimentin, histone, alpha-enolase, and IgA RF (p<0.001), IgG RF (p = 0.049), and IgM RF (p = 0.004), while anti-P. gingivalis and anti-F. nucleatum were not.

CONCLUSIONS

No longitudinal elevations of anti-bacterial serum antibody concentrations were observed in RA patients prior to RA diagnosis compared to controls. However, anti-P. intermedia displayed significant associations with RA autoantibody concentrations prior to RA diagnosis, suggesting a potential role of this organism in progression towards clinically-detectable RA.

Influence of periodontitis on levels of autoantibodies in rheumatoid arthritis patients: A systematic review

BACKGROUND AND OBJECTIVE

Periodontitis (PD) is a dysbiotic disease of tooth-supporting structures that has been associated with various systemic diseases including rheumatoid arthritis (RA). To date, evidence demonstrated increased prevalence of RA among PD patients and postulated PD to have a role in the development of autoantibodies in RA patients. Therefore, a systematic review was conducted to assess the available evidence to ascertain the effect of PD on levels of autoantibodies in the serum, saliva and gingival crevicular fluid (GCF) of RA patients.

MATERIAL AND METHODS

The systematic review was conducted in compliance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. Relevant literature was searched from PubMed, Web of Science, Scopus and Ebscohost databases from inception until 31 August 2020. The risk of bias in each study was determined based on the Newcastle-Ottawa Scale tool. Results from random-effect meta-analyses were presented as summary estimates of odds ratios (ORs) for seropositivity and standardised mean difference (SMD) of autoantibody levels with 95% confidence intervals. Sensitivity tests and meta-regression were performed to assess the robustness of the results and potential cause of heterogeneity.

RESULTS

The electronic and manual searches gathered 932 articles. Following screening and full-text assessment, a total of 29 studies were included in the analysis. Twenty-eight published observational studies were included in the quantitative analysis in the form of random-effect meta-analysis which revealed that PD was associated with anti-citrullinated proteins autoantibodies (ACPAs) and Rheumatoid Factor (RF) seropositive RA patients (OR for ACPA seropositivity: 1.82; 95% CI: 1.13-2.93) (OR for RF seropositivity: 1.53; 95% CI: 1.05-2.24). Also, RA patients with PD had increased serum levels of ACPA and RF. However, high heterogeneity among studies' results, partially ascribed to the unstandardised case definition of PD and laboratory testing of autoantibodies. Apart from ACPA and RF in serum, studies which reported on other RA-related autoantibodies, as well as autoantibody levels in saliva and GCF were scarce.

CONCLUSION

RA patients with PD tend to have greater ACPA and RF levels in their serum when compared with the RA patients without PD supporting the plausible role of PD in the development of systemic autoimmunity in RA patients.

Dental caries and risk of newly-onset systemic lupus erythematosus: a nationwide population-based cohort study

OBJECTIVE

This study investigated whether patients with history of dental caries are associated with an increased risk of newly-onset systemic lupus erythematosus (SLE).

METHODS

A total of 501,461 carious patients and 258,918 controls without carious teeth were enrolled between 1997 and 2013 from the National Health Insurance Research Database. Subgroup analyses were conducted based on restorative materials including amalgam, composite resins, or both. The cumulative incidence and hazard ratios (HRs) of SLE development were derived after adjusting for age, sex, socioeconomic status, income, insured classification, comorbidities, and frequency of dental visit in a multivariable model.

RESULTS

The risk of SLE was significantly higher in carious patients (HR = 1.98, 95% confidence interval [CI] = 1.65-2.38) compared to controls. Dose-dependent relationship between caries and risk of SLE was identified. The risk of SLE was higher among those who had dental visits ≧11 (HR = 2.53, 95% CI = 1.86-3.43), followed by those with 3-10 dental visits (HR = 1.86, 95% CI = 1.36-2.54), when compared to those with 1-2 visits, and was higher among those who had carious teeth extractions ≧5 (HR = 1.88, 95% CI = 1.19-2.97), followed by those with 1-4 carious teeth extractions (HR = 1.36, 95% CI = 1.17-1.59) than those without extraction. The risk of SLE for dental caries management among different restorative materials, including amalgam, composite resins, or both, was not statistically different.

CONCLUSIONS

Patients with dental caries were associated with higher SLE risks. The relationship between dental caries and risk of SLE was dose-dependent, regardless of the material used for the restoration.

Effects of intestinal microbes on rheumatic diseases: A bibliometric analysis

Background

Rheumatic diseases (RD) are a group of multi-system inflammatory autoimmune diseases whose causes are still under study. In the past few decades, researchers have found traces of the association between rheumatic diseases and intestinal microbiota, which can partially explain the pathogenesis of rheumatic diseases. We aimed to describe the research trend and main divisions on how gut flora interreacts with rheumatic diseases, and discussed about the possible clinical applications.

Methods

We analyzed bibliometric data from the Web of Science core collection (dated 15th May 2022). Biblioshiny R language software packages (bibliometrix) were used to obtain the annual publication and citations, core sources according to Bradford's law, and country collaboration map. We designed and verified the keyword co-occurrence network and strategic diagram with the help of VOSviewer and CiteSpace, subdivided the research topic into several themes and identified research dimensions. The tables of most local cited documents and core sources were processed manually. Furthermore, the Altmetric Attention Score and the annual Altmetric Top 100 were applied to analyze the annual publication and citation.

Results

From a total of 541 documents, we found that the overall trend of annual publication and citation is increasing. The major research method is to compare the intestinal microbial composition of patients with certain rheumatic disease and that of the control group to determine microbial alterations related to the disease's occurrence and development. According to Bradford's law, the core sources are Arthritis and Rheumatology, Annals of the Rheumatic Diseases, Current Opinion in Rheumatology, Nutrients, Rheumatology, and Journal of Rheumatology. Since 1976, 101 countries or regions have participated in studies of rheumatology and intestinal microbes. The United States ranks at the top and has the broadest academic association with other countries. Five themes were identified, including the pivotal role of inflammation caused by intestinal bacteria in the rheumatic pathogenesis, the close relationship between rheumatic diseases and inflammatory bowel disease, immunoregulation mechanism as a mediator of the interaction between rheumatic diseases and gut flora, dysbiosis and decreased diversity in intestine of patients with rheumatic diseases, and the influence of oral flora on rheumatic diseases. Additionally, four research dimensions were identified, including pathology, treatment, disease, and experiments.

Conclusion

Studies on rheumatic diseases and the intestinal microbiota are growing. Attention should be paid to the mechanism of their interaction, such as the microbe-immune-RD crosstalk. Hopefully, the research achievements can be applied to diseases' prevention, diagnosis, and treatment, and our work can contribute to the readers' future research.

Association between Porphyromonas Gingivalis and systemic diseases: Focus on T cells-mediated adaptive immunity

The association between periodontal disease and systemic disease has become a research hotspot. Porphyromonas gingivalis (P. gingivalis), a crucial periodontal pathogen, affects the development of systemic diseases. The pathogenicity of P. gingivalis is largely linked to interference with the host's immunity. This review aims to discover the role of P. gingivalis in the modulation of the host's adaptive immune system through a large number of virulence factors and the manipulation of cellular immunological responses (mainly mediated by T cells). These factors may affect the cause of large numbers of systemic diseases, such as atherosclerosis, hypertension, adverse pregnancy outcomes, inflammatory bowel disease, diabetes mellitus, non-alcoholic fatty liver disease, rheumatoid arthritis, and Alzheimer's disease. The point of view of adaptive immunity may provide a new idea for treating periodontitis and related systemic diseases.

Are Viral Infections Key Inducers of Autoimmune Diseases? Focus on Epstein–Barr Virus

It is generally accepted that certain viral infections can trigger the development of autoimmune diseases. However, the exact mechanisms by which these viruses induce autoimmunity are still not understood. In this review, we first describe hypothetical mechanisms by which viruses induce some representative autoimmune diseases. Then, we focus on Epstein–Barr virus (EBV) and discuss its role in the pathogenesis of rheumatoid arthritis (RA). The discussion is mainly based on our own previous findings that (A) EBV DNA and its products EBV-encoded small RNA (EBER) and latent membrane protein 1 (LMP1) are present in the synovial lesions of RA, (B) mRNA expression of the signaling lymphocytic activation molecule-associated protein (SAP)/SH2D1A gene that plays a critical role in cellular immune responses to EBV is reduced in the peripheral T cells of patients with RA, and (C) EBV infection of mice reconstituted with human immune system components (humanized mice) induced erosive arthritis that is pathologically similar to RA. Additionally, environmental factors may contribute to EBV reactivation as follows: Porphyromonas gingivalis peptidylarginine deiminase (PAD), an enzyme required for citrullination, engenders antigens leading to the production of citrullinated peptides both in the gingiva and synovium. Anti-citrullinated peptides autoantibody is an important marker for diagnosis and disease activity of RA. These findings, as well as various results obtained by other researchers, strongly suggest that EBV is directly involved in the pathogenesis of RA, a typical autoimmune disease.

Disease mechanisms in preclinical rheumatoid arthritis: A narrative review

In the last decades, the concept of preclinical rheumatoid arthritis (RA) has become established. In fact, the discovery that disease mechanisms start years before the onset of clinical RA has been one of the major recent insights in the understanding of RA pathogenesis. In accordance with the complex nature of the disease, preclinical events extend over several sequential phases. In a genetically predisposed host, environmental factors will further increase susceptibility for incident RA. In the initial steps of preclinical disease, immune disturbance mechanisms take place outside the joint compartment, namely in mucosal surfaces, such as the lung, gums or gut. Herein, the persistent immunologic response to altered antigens will lead to breach of tolerance and trigger autoimmunity. In a second phase, the immune response matures and is amplified at a systemic level, with epitope spreading and widening of the autoantibody repertoire. Finally, the synovial and bone compartment are targeted by specific autoantibodies against modified antigens, initiating a local inflammatory response that will eventually culminate in clinically evident synovitis. In this review, we discuss the elaborate disease mechanisms in place during preclinical RA, providing a broad perspective in the light of current evidence.

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.

Phytochemicals from medicinal plants from African forests with potentials in rheumatoid arthritis management

OBJECTIVES

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by inflammation, pain, and cartilage and bone damage. There is currently no cure for RA. It is however managed using nonsteroidal anti-inflammatory drugs, corticosteroids and disease-modifying anti-rheumatic drugs, often with severe side effects. Hidden within Africa's lush vegetation are plants with diverse medicinal properties including anti-RA potentials. This paper reviews the scientific literature for medicinal plants, growing in Africa, with reported anti-RA activities and identifies the most abundant phytochemicals deserving research attention. A search of relevant published scientific literature, using the major search engines, such as Pubmed/Medline, Scopus, Google Scholar, etc. was conducted to identify medicinal plants, growing in Africa, with anti-RA potentials.

KEY FINDINGS

Twenty plants belonging to 17 families were identified. The plants are rich in phytochemicals, predominantly quercetin, rutin, catechin, kaempferol, etc., known to affect some pathways relevant in RA initiation and progression, and therefore useful in its management.

SUMMARY

Targeted research is needed to unlock the potentials of medicinal plants by developing easy-to-use technologies for preparing medicines from them. Research attention should focus on how best to exploit the major phytochemicals identified in this review for the development of anti-RA 'green pharmaceuticals'.

Influence of Oral Microbiota on the Presence of IgA Anti-Citrullinated Protein Antibodies in Gingival Crevicular Fluid

Introduction

The relation between rheumatoid arthritis (RA) and periodontitis (PD) has been investigated ever since the discovery of the citrullinating enzyme peptidyl arginine deaminase presents in the oral bacterium Porphyromonas gingivalis. Recently, we demonstrated the presence of RA autoantibodies, especially of IgA anti-citrullinated protein antibody (ACPA), in gingival crevicular fluid (GCF) of Indonesian patients with and without RA or PD which might indicate the local formation of RA antibodies in the periodontium.

Aim

The purpose of this study was to assess whether the subgingival microbiome is related to the presence of IgA ACPA in the GCF of healthy individuals with or without PD.

Patients and Methods

Healthy individuals with a known periodontal status and high IgA ACPA (>0.1 U/ml) in GCF (n = 27) were selected and matched for age, gender, periodontal status, and smoking status with 27 healthy individuals without IgA ACPA in their GCF. Taxonomic profiling of the subgingival microbiome was based on bacterial 16S rRNA gene sequencing. Downstream analyses were performed to assess compositional differences between healthy subjects with or without IgA ACPA in GCF and with or without PD.

Results

Between groups with or without PD, or with or without IgA ACPA in GCF, no differences in alpha diversity were seen. Beta diversity was different between groups with or without PD (p < 0.0001), and a trend was seen in subjects with PD between subjects with or without IgA ACPA in GCF (p = 0.084). Linear discriminant analysis effect size (LEfSe) revealed no significant differences in the total population between subjects with IgA ACPA compared to subjects without IgA ACPA in GCF. Although Porphyromonas was not identified by LEfSe, its relative abundance was significantly higher in healthy individuals with high IgA ACPA in GCF compared to individuals without IgA ACPA in GCF (p = 0.0363). Zooming in on the subgroup with PD, LEfSe revealed that species Neisseriaceae, Tannerella, and Haemophilus were more abundant in the subjects with IgA ACPA in GCF compared to subjects without IgA ACPA in GCF.

Conclusion

Periodontitis and certain taxa, including Porphyromonas, seem to be associated with the local presence of ACPA in the periodontium.

Antibodies to a Citrullinated Porphyromonas gingivalis Epitope Are Increased in Early Rheumatoid Arthritis, and Can Be Produced by Gingival Tissue B Cells: Implications for a Bacterial Origin in RA Etiology

Based on the epidemiological link between periodontitis and rheumatoid arthritis (RA), and the unique feature of the periodontal bacterium Porphyromonas gingivalis to citrullinate proteins, it has been suggested that production of anti-citrullinated protein antibodies (ACPA), which are present in a majority of RA patients, may be triggered in the gum mucosa. To address this hypothesis, we investigated the antibody response to a citrullinated P. gingivalis peptide in relation to the autoimmune ACPA response in early RA, and examined citrulline-reactivity in monoclonal antibodies derived from human gingival B cells. Antibodies to a citrullinated peptide derived from P. gingivalis (denoted CPP3) and human citrullinated peptides were analyzed by multiplex array in 2,807 RA patients and 372 controls; associations with RA risk factors and clinical features were examined. B cells from inflamed gingival tissue were single-cell sorted, and immunoglobulin (Ig) genes were amplified, sequenced, cloned and expressed (n=63) as recombinant monoclonal antibodies, and assayed for citrulline-reactivities by enzyme-linked immunosorbent assay. Additionally, affinity-purified polyclonal anti-cyclic-citrullinated peptide (CCP2) IgG, and monoclonal antibodies derived from RA blood and synovial fluid B cells (n=175), were screened for CPP3-reactivity. Elevated anti-CPP3 antibody levels were detected in RA (11%), mainly CCP2+ RA, compared to controls (2%), p<0.0001, with a significant association to HLA-DRB1 shared epitope alleles, smoking and baseline pain, but with low correlation to autoimmune ACPA fine-specificities. Monoclonal antibodies derived from gingival B cells showed cross-reactivity between P. gingivalis CPP3 and human citrullinated peptides, and a CPP3+/CCP2+ clone, derived from an RA blood memory B cell, was identified. Our data support the possibility that immunity to P. gingivalis derived citrullinated antigens, triggered in the inflamed gum mucosa, may contribute to the presence of ACPA in RA patients, through mechanisms of molecular mimicry.

Association between gestational diabetes mellitus and periodontitis via the effect of reactive oxygen species in peripheral blood cells

BACKGROUND

Periodontitis (P) has emerged as a risk factor for gestational diabetes mellitus (GDM) through immune cell function alterations, elevated proinflammatory mediators, and increased reactive oxygen species (ROS). The main objective of present study was to determine associations between pregnancy with and without GDM and P. The secondary objective was to compare ROS production in peripheral blood cells (PBCs) of pregnant women with and without GDM.

METHODS

This cross-sectional case-control study included 128 pregnant women: 64 with and 64 without GDM. All participants were examined for clinical parameters of GDM and periodontal conditions. Associations between GDM-related periodontal data and GDM risk were evaluated by multiple logistic regression. PBCs were isolated and cultured. ROS productions in each PBCs types was investigated by flow cytometry with ROS antibodies.

RESULTS

P was significantly more prevalent in pregnant women with GDM than in those without GDM (57.8% versus 37.5%), with an odds ratio (OR) of 2.28, and a 95% confidence interval (CI) of 1.12 to 4.64 (P = 0.022). The OR (95% CI) was 2.59 (1.19 to 5.65) (P = 0.017) after adjusting for potential confounding factors, including diabetes mellitus (DM) family history, age ≥30 years, body mass index, and maternal age. ROS levels in all PBCs types were significantly higher in the GDM than in the non-GDM group (P < 0.05).

CONCLUSION

This study supported the association between P and GDM and indicated that P may be a risk factor for GDM. High levels of ROS production in the PBCs of pregnant women with GDM emphasized the association with GDM.

Infectious agents breaking the immunological tolerance: The holy grail in rheumatoid arthritis (RA) reconsidered

Multiple Sclerosis (MS) has been shown to be linked to Epstein Barr Virus (EBV) infection, a virus that infects B cells inside the CNS. The seminal study raises a key interest into the infectious origin of several other autoimmune inflammatory diseases.We will discuss here the infectious agents that have been studied over the years in Rheumatoid Arthritis (RA), a crippling arthritis that was treated a century ago with gold salts (anti mycobacterial agent), with chloroquine (anti malarial agent), or sulphasalazine (an antibacterial-antiinflammatory agent). Several infectious agents have been taken into consideration i.e. Streptococcus group A, Proteus, Mycobacterium tuberculosis-MTB, Parvovirus B19, Epstein Barr virus, Porphyromonas gengivalis-Pg, Aggregatibacter actinomycetescomitans, and finally Haemophilus -Glaesserella parasuis-Hps. Of these agents only three satisfy the Witebski's criteria as possible pathogenetic causes of an autoimmune disease, MTB, Pg, Hps. We will discuss here how the immune tolerance might be broken, which could be the neoantigen or autoantigen involved, how the infectious agent was studied as a trigger capable of inducing arthritis in animal models. The preventive measures that should be adopted to lessen the impact of the infections, to prevent the burden and the severity of the illness are described.

Salivary Microbiota and Host-Inflammatory Responses in Periodontitis Affected Individuals With and Without Rheumatoid Arthritis

Objectives

Periodontitis and rheumatoid arthritis (RA) are two widespread chronic inflammatory diseases with a previously suggested association. The objective of the current study was to compare the oral microbial composition and host´s inflammatory mediator profile of saliva samples obtained from subjects with periodontitis, with and without RA, as well as to predict biomarkers, of bacterial pathogens and/or inflammatory mediators, for classification of samples associated with periodontitis and RA.

Methods

Salivary samples were obtained from 53 patients with periodontitis and RA and 48 non-RA with chronic periodontitis. The microbial composition was identified using 16S rRNA gene sequencing and compared across periodontitis patients with and without RA. Levels of inflammatory mediators were determined using a multiplex bead assay, compared between the groups and correlated to the microbial profile. The achieved data was analysed using PCoA, DESeq2 and two machine learning algorithms, OPLS-DA and sPLS-DA.

Results

Differential abundance DESeq2 analyses showed that the four most highly enriched (log2 FC >20) amplicon sequence variants (ASVs) in the non-RA periodontitis group included Alloprevotella sp., Prevotella sp., Haemophilus sp., and Actinomyces sp. whereas Granulicatella sp., Veillonella sp., Megasphaera sp., and Fusobacterium nucleatum were the most highly enriched ASVs (log2 FC >20) in the RA group. OPLS-DA with log2 FC analyses demonstrated that the top ASVs with the highest importance included Vampirovibrio sp. having a positive correlation with non-RA group, and seven ASVs belonging to Sphingomonas insulae, Sphingobium sp., Novosphingobium aromaticivorans, Delftia acidovorans, Aquabacterium spp. and Sphingomonas echinoides with a positive correlation with RA group. Among the detected inflammatory mediators in saliva samples, TWEAK/TNFSF12, IL-35, IFN-α2, pentraxin-3, gp130/sIL6Rb, sIL-6Ra, IL-19 and sTNF-R1 were found to be significantly increased in patients with periodontitis and RA compared to non-RA group with periodontitis. Moreover, correlations between ASVs and inflammatory mediators using sPLS-DA analysis revealed that TWEAK/TNFSF12, pentraxin-3 and IL-19 were positively correlated with the ASVs Sphingobium sp., Acidovorax delafieldii, Novosphingobium sp., and Aquabacterium sp.

Conclusion

Our results suggest that the combination of microbes and host inflammatory mediators could be more efficient to be used as a predictable biomarker associated with periodontitis and RA, as compared to microbes and inflammatory mediators alone.

Associations between inflammation-related LL-37 with subgingival microbial dysbiosis in rheumatoid arthritis patients

OBJECTIVE

This study investigated the subgingival microbial profile of rheumatoid arthritis (RA) patients and its associations with disease parameters and the inflammation-related antimicrobial peptide, LL-37.

METHODS

RA and non-RA (NRA) patients were assessed for periodontal status and divided into periodontitis (CP), gingivitis (G), and healthy (H) groups. Subgingival plaque 16s rRNA gene sequencing data was processed and analyzed using the CLC Genomic Workbench (Qiagen). Bacterial diversity and co-occurrence patterns were examined. Differential abundance between groups was also investigated. Associations between bacterial genera with disease parameters and LL-37 levels were explored qualitatively using canonical correlation analysis.

RESULTS

Subgingival microbial community clustered in CP status. Co-occurrence network in NRA-H was dominated by health-associated genera, while the rest of the networks' key genera were both health- and disease-associated. RA-CP displayed highly inter-generic networks with a statistically significant increase in periodontal disease-associated genera (p<0.05). In NRA-H, disease parameters and LL-37 were correlated positively with disease-associated genera while negatively with health-associated genera. However, in the remaining groups, mixed positive and negative correlations were noted with genera.

CONCLUSION

RA patients demonstrated subgingival microbial dysbiosis where the bacteria networks were dominated by health- and disease-associated genera. Mixed correlations with disease parameters and LL-37 levels were noted.

CLINICAL RELEVANCE

The subgingival microbial dysbiosis in RA may predispose these patients to developing periodontal inflammation with an associated detrimental effect on host immune responses. Routine periodontal assessment may allow initiation of treatment strategies to minimize the effects of gingival inflammation on the existing heightened immune response present in RA patients.

Antibodies to Porphyromonas gingivalis Are Increased in Patients with Severe Periodontitis, and Associate with Presence of Specific Autoantibodies and Myocardial Infarction

There is accumulating data suggesting that periodontitis is associated with increased risk of systemic and autoimmune diseases, including cardiovascular disease, rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), and there is an unmet need to identify these individuals early. With the periodontal bacteria Porphyromonas gingivalis (Pg) as one of the key drivers of periodontitis, we set out to investigate whether antibodies to Pg virulence factor arginine gingipain (Rgp) could serve as a biomarker for periodontitis patients at increased risk of autoimmunity and systemic disease. We measured serum anti-Rgp IgG in three study populations: PAROKRANK (779 individuals with myocardial infarction (MI); 719 controls), where 557 had periodontitis, and 312 were positive for autoantibodies associated with RA/SLE; the PerioGene North pilot (41 periodontitis; 39 controls); and an SLE case/control study (101 SLE; 100 controls). Anti-Rgp IgG levels were increased in severe periodontitis compared to controls (p < 0.0001), in individuals positive for anti-citrullinated protein antibodies (p = 0.04) and anti-dsDNA antibodies (p = 0.035), compared to autoantibody-negative individuals; and in MI patients versus matched controls (p = 0.035). Our data support longitudinal studies addressing the role of anti-Rgp antibodies as biomarkers for periodontitis patients at increased risk of developing autoimmunity linked to RA and SLE, and mechanisms underpinning these associations.

Etiology and Risk Factors for Rheumatoid Arthritis: A State-of-the-Art Review

Rheumatoid arthritis (RA) is the most common systemic inflammatory rheumatic disease. It is associated with significant burden at the patient and societal level. Extensive efforts have been devoted to identifying a potential cause for the development of RA. Epidemiological studies have thoroughly investigated the association of several factors with the risk and course of RA. Although a precise etiology remains elusive, the current understanding is that RA is a multifactorial disease, wherein complex interactions between host and environmental factors determine the overall risk of disease susceptibility, persistence and severity. Risk factors related to the host that have been associated with RA development may be divided into genetic; epigenetic; hormonal, reproductive and neuroendocrine; and comorbid host factors. In turn, environmental risk factors include smoking and other airborne exposures; microbiota and infectious agents; diet; and socioeconomic factors. In the present narrative review, aimed at clinicians and researchers in the field of RA, we provide a state-of-the-art overview of the current knowledge on this topic, focusing on recent progresses that have improved our comprehension of disease risk and development.

Association of Serum and Crevicular Fluid Dickkopf-1 Levels with Disease Activity and Periodontitis in Patients with Early Rheumatoid Arthritis

BACKGROUND

The aim of this study was to assess DKK-1 levels, in Gingival Crevicular Fluid (GCF) and serum, as a biomarker for bone loss and disease activity in periodontitis and early RA (eRA).

METHODS

In this cross-sectional study, we obtained serum and GCF from 10 interproximal sites (Distal Buccal I/S, Mesio Buccal I/S, Distal Palatal/Lingual, Mesio Palatal/Lingual) according to the highest degree of inflammation by a patient for 240 sites from eRA patients. Patients received a periodontal assessment, a radiographic evaluation, tomography of interproximal sites, and DKK1 levels were determined by ELISA. Comparisons were performed by the Mann-Whitney U test and analysis by Chi2 test, and a logistic regression model was applied.

RESULTS

The mean age was 46.33 ± 12.0 years, the Disease Activity Score (DAS-28-ESR) was 4.08 ± 1.4. Periodontitis was present in 65.2% of the patients, and 59.6% of these patients had bone loss in interproximal sites. Higher GCF-DKK1 levels were associated with serum-DKK1 (OR:2.41 IC95% 1.14-5.09, p=0.021) and were related with DAS28-ESR (p=0.001), Routine Assessment of Patient Index Data 3 (RAPID 3) (p=0.001), and tender joints (p=0.040). Foot bone erosion and juxta-articular osteopenia were associated with high levels of serum-DKK1 (p=0.009 and 0.001, respectively). Serum-DKK1 were associated with SDAI (OR: 2.38 IC95% 1.03-5.52, p=0.043), RAPID 3 (p=0.001), and rheumatoid factor (p=0.018). The GCF-DKK1 levels were associated with periodontal bone loss (p=0.011), periodontitis (p=0.070) and its severity (OR: 2.58 IC95% 2.28-7.28, p=0.001). Bone loss was more frequent in buccal sites (73.5%) and was associated with increased levels of DKK1 (p=0.033).

CONCLUSION

In the early stages of the eRA disease, serum and GCF-DKK1 could be a biomarker for clinical disease activity and periodontal and articular bone erosion.

Anti-alpha enolase multi-antibody specificity in human diseases. Clinical significance and molecular mechanisms

Alpha-enolase (Eno) is an ubiquitary glycolytic enzyme playing multiple functions that go well beyond its principal metabolic role of energy supplier during glycolysis. Eno is localized in the cytoplasm, but also expressed on the cell membrane, where it binds plasminogen allowing its activation. Its shorter form, in the nucleus, acts as transcription factor. In inflammatory conditions, Eno undergoes post-translational modifications, such as citrullination, oxidation and phosphorylation. Eno is also an autoantigen in different disorders. In fact, autoantibodies to Eno have been detected in rheumatoid arthritis, lupus nephritis, primary glomerulonephritis, cancer, infections and other disorders, and in many cases they represent specific markers to be utilized in clinical practice. Anti-Eno antibodies in the different clinical conditions are not equal: they differ in isotype and often recognize different epitopes on the enzyme. IgG1 and IgG3 are prevalent in Rheumatoid Arthritis, IgG2 in Lupus nephritis and IgG4 in primary autoimmune glomerulopathy. This review analyzes the characteristics of anti-Eno autoantibodies in autoimmune disorders and cancer, describing their fine specificity and isotype restriction. The post-translational modifications that are target of autoantibodies are also discussed, as they represent the basis for elucidating the molecular mechanisms responsible for epitope generation. Despite an impressive amount of experimental work on anti-Eno antibodies, it is still necessary to validate the use of anti-Eno antibodies as biomarkers of selected diseases and extend the knowledge on the mechanisms of anti-Eno autoantibody production. Strategies that downmodulate the immune response to Eno may represent in the future novel approaches in the treatment of autoimmune disorders.

No Obvious Role for Suspicious Oral Pathogens in Arthritis Development

A particular role for Porphyromonas gingivalis (Pg) and Aggregatibacter actinomycetemcomitans (Aa) has been suggested in periodontitis and rheumatoid arthritis (RA), as these bacteria could initiate the formation of rheumatoid factor (RF) and anticitrullinated protein autoantibodies (ACPA). We assessed whether serum antibodies against Pg and Aa in RA patients and non-RA controls reflect the subgingival presence of Pg and Aa, and evaluated the relationship of these antibodies to the severity of periodontal inflammation and RA-specific serum autoantibodies. In 70 Indonesian RA patients and 70 non-RA controls, the subgingival presence of Pg and Aa was assessed by bacterial 16S rRNA gene sequencing, and serum IgG levels specific for Pg and Aa were determined. In parallel, serum levels of ACPA (ACPA:IgG,IgA) and RF (RF:IgM,IgA) were measured. The extent of periodontal inflammation was assessed by the periodontal inflamed surface area. In both RA patients and the controls, the presence of subgingival Pg and Aa was comparable, anti-Pg and anti-Aa antibody levels were associated with the subgingival presence of Pg and Aa, and anti-Pg did not correlate with ACPA or RF levels. The subgingival Pg and Aa were not related to RA. No noteworthy correlation was detected between the antibodies against Pg and Aa, and RA-specific autoantibodies.

Oral Microbiota Identifies Patients in Early Onset Rheumatoid Arthritis

Rheumatoid arthritis (RA) is the most common autoimmune inflammatory disease, and single periodontitis-associated bacteria have been suggested in disease manifestation. Here, the oral microbiota was characterized in relation to the early onset of RA (eRA) taking periodontal status into consideration. 16S rRNA gene amplicon sequencing of saliva bacterial DNA from 61 eRA patients without disease-modifying anti-rheumatic drugs and 59 matched controls was performed. Taxonomic classification at 98.5% was conducted against the Human Oral Microbiome Database, microbiota functions were predicted using PICRUSt, and periodontal status linked from the Swedish quality register for clinically assessed caries and periodontitis. The participants were classified into three distinct microbiota-based cluster groups with cluster allocation differences by eRA status. Independently of periodontal status, eRA patients had enriched levels of Prevotella pleuritidis, Treponema denticola, Porphyromonas endodontalis and Filifactor alocis species and in the Porphyromonas and Fusobacterium genera and functions linked to ornithine metabolism, glucosylceramidase, beta-lactamase resistance, biphenyl degradation, fatty acid metabolism and 17-beta-estradiol-17-dehydrogenase metabolism. The results support a deviating oral microbiota composition already in eRA patients compared with healthy controls and highlight a panel of oral bacteria that may be useful in eRA risk assessment in both periodontally healthy and diseased persons.

Antibodies against citrullinated proteins in relation to periodontitis with or without rheumatoid arthritis: a cross-sectional study

Background

Previous studies have reported conflicting findings between serum anti-citrullinated protein antibodies (ACPA) levels in rheumatoid arthritis (RA) participants with and without periodontitis (Pd). This study aimed to analyse possible correlations between serum ACPA levels and clinical parameters in Pd and RA participants.

Methods

Full mouth periodontal examination (probing pocket depth, clinical attachment levels, gingival bleeding index, visual plaque index) was conducted and serum samples obtained from 80 participants comprising RA, Pd, both RA and Pd (RAPd) and healthy individuals (HC). Erythrocyte sedimentation rates (ESR) and periodontal inflamed surface area (PISA) were obtained. Serum samples were analysed for ACPA quantification using enzyme-linked immunosorbent assay (ELISA).

Results

Median levels (IU/mL) of ACPA (interquartile range, IQR) in RAPd, RA, Pd and HC groups were 118.58(274.51), 102.02(252.89), 78.48(132.6) and 51.67(91.31) respectively. ACPA levels were significantly higher in RAPd and RA as compared to HC group (p < 0.05). However, ACPA levels of any of the groups were not correlated with any clinical periodontal and RA parameters within the respective groups.

Conclusions

At individual level, the amount of serum ACPA seem to have an increasing trend with the diseased condition in the order of RAPd > RA > Pd > HC. However, lack of any significant correlation between the serum ACPA levels with the clinical Pd and RA parameters warrants further studies to investigate the causal link between RA and Pd for such a trend. Further studies involving more inflammatory biomarkers might be useful to establish the causal link between Pd in the development and progression of RA or vice versa.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01712-y.

Microbiome in Rheumatoid Arthritis and Celiac Disease: A Friend or Foe

Rheumatoid arthritis (RA) and celiac disease (CD) are both autoimmune diseases with increasing global prevalence. These two diseases have been connected based on similar HLA mutations, serological markers, rheumatological, and gastrointestinal manifestations. In this review, we discuss the role of the oral and gut microbiome in the development and progression of RA and CD. Here, we highlight similar microbial dysbiosis and how these alterations in composition can lead to worsening disease severity in both CD and RA. Additionally, we analyze the role of probiotics in regulating the microbiome and improving symptoms associated with RA and CD.

Exploring the Oral Microbiome in Rheumatic Diseases, State of Art and Future Prospective in Personalized Medicine with an AI Approach

The oral microbiome is receiving growing interest from the scientific community, as the mouth is the gateway for numerous potential etiopathogenetic factors in different diseases. In addition, the progression of niches from the mouth to the gut, defined as "oral-gut microbiome axis", affects several pathologies, as rheumatic diseases. Notably, rheumatic disorders (RDs) are conditions causing chronic, often intermittent pain affecting the joints or connective tissue. In this review, we examine evidence which supports a role for the oral microbiome in the etiology and progression of various RDs, including rheumatoid arthritis (RA), Sjogren's syndrome (SS), and systemic lupus erythematosus (SLE). In addition, we address the most recent studies endorsing the oral microbiome as promising diagnostic biomarkers for RDs. Lastly, we introduce the concepts of artificial intelligence (AI), in particular, machine learning (ML) and their general application for understanding the link between oral microbiota and rheumatic diseases, speculating the application of a possible AI approach-based that can be applied to personalized medicine in the future.

Exposure to Porphyromonas gingivalis and Modifiable Risk Factors Modulate Risk for Early Diabetic Retinopathy

Purpose

We hypothesized that exposure to Porphyromonas gingivalis (Pg) increases the risk for early diabetic retinopathy (DR) and that the risk can be modulated.

Methods

We identified 116 early DR cases, and 116 non-DR controls were selected randomly by frequency matching for age, sex, race, and education from the US Third National Health and Nutrition Examination Survey. DR was assessed using non-mydriatic fundus photographs and graded by trained graders using the Modified Airlie House Classification scheme and the Early Treatment for Diabetic Retinopathy Study severity scale. Serum Pg immunoglobulin G (IgG) antibody (Ab) was measured in enzyme-linked immunosorbent assay units. Logistic regression was used to relate serum Pg IgG Ab levels to the risk for early DR.

Results

Per tenfold increase in Pg IgG Ab levels, there was an over 60% increased risk for early DR (odds ratio = 1.64; 95% confidence interval, 1.36–1.97), and a linear trend was noted for the estimated probabilities of early DR at various Pg IgG Ab levels (P for trend = 0.0053). The analysis also suggested that moderate alcohol consumption (less than 12 drinks in the past 12 months; P for interaction = 0.0003) and maintaining a normal serum glycated hemoglobulin level (HbA1c ≤ 5.7%; P for interaction < 0.0001) helped reduce the Pg-related DR risk.

Conclusions

The increased Pg-related DR risk could be alleviated by managing alcohol consumption and maintaining a normal blood glucose level.

Translational Relevance

Findings from this study provide new directions for developing novel therapeutics and prevention strategies for DR.

Interplay of Microbiota and Citrullination in the Immunopathogenesis of Rheumatoid Arthritis

Microbiota is a balanced ecosystem that has important functions to the host health including development, defense, digestion, and absorption of dietary fibers and minerals, vitamin synthesizes, protection, and training the host immune system. On the other hand, its dysbiosis is linked to many human diseases such as rheumatoid arthritis (RA). The RA is an inflammatory autoimmune disorder caused by genetic and environmental factors; microbiota may be considered as a risk environmental factor for it. Citrullination is a post-translation modification (PMT) that converts the amino acid arginine to amino acid citrulline in certain proteins. These citrullinated proteins are recognized as a foreign antigen by the immune system resulting in the upregulation of inflammatory action such as in RA. The current work highlights the effect of both gut and oral microbiota dysbiosis on the development of RA, as well as discusses how the alteration in microbiota composition leads to the overgrowth of some bacterial species that entangled in RA pathogenicity. The evidence suggested that some oral and gut microbial species such as Porphyromonas gingivalis and Prevotella copri, respectively, contribute to RA pathogenesis. During dysbiosis, these bacteria can mediate the citrullination of either human or bacteria proteins to trigger an immune response that leads to the generation of autoantibodies.

Soluble neuropilin-1 in gingival crevicular fluid is associated with rheumatoid arthritis: An exploratory case-control study

Background

To explore the soluble Neuropilin-1 (sNRP-1) concentrations in gingival crevicular fluid (GCF) and the periodontal clinical status of patients with Rheumatoid Arthritis (RA).

Materials and methods

We conducted an exploratory study with 40 study participants, 20 with RA, and 20 healthy controls. Clinical and periodontal data were recorded, and GCF samples were obtained. sNRP-1 levels in GCF were determined by ELISA assay. Descriptive statistics, Mann-Whitney U test, Unpaired t-test, logistic regression model, and Area Under Receiver Operating Characteristic Curve (AUC-ROC) were made to explore the diagnostic performance accuracy.

Results

RA patients had significantly higher levels of sNRP-1 in GCF (p ​= ​0.0447). The median levels of GCF-sNRP-1 were 208.85 ​pg/μl (IQR 131.03) in the RA group compared to 81.46 ​pg/μl (IQR 163.73) in the control group. We observed an association between the GCF-sNRP-1 concentrations and the RA diagnosis (OR:1.009; CI 1.00-1.001; p ​= ​0.047). The diagnosis of chronic periodontitis was also associated with RA (OR: 6.9; CI 1.52-31.37; p ​= ​0.012). Moreover, the AUC-ROC of GCF-sNRP-1 concentrations combined with periodontal clinical parameters such as periodontal probing depth and periodontal inflamed surface area was 0.80.

Conclusion

This exploratory case-control study shows that RA patients had significantly higher levels of sNRP-1 in GCF. New longitudinal studies are necessary to evaluate the role of NRP-1 in periodontal tissues and consider it an oral biomarker with clinical value in RA.

The pre-clinical phase of rheumatoid arthritis: From risk factors to prevention of arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease considered as a multistep process spanning from the interaction of genetic (e.g., shared epitope or non-HLA loci), environmental and behavioral risk factors (e.g., smoking) leading to breaking immune tolerance and autoimmune processes such as the production of autoantibodies (e.g., antibodies against citrullinated proteins ACPA or rheumatoid factors, RF), development of the first symptoms without clinical arthritis, and, finally, the manifestation of arthritis. Despite the typical joint involvement in established RA, the pathogenesis of the disease likely begins far from joint structures: in the lungs or periodontium in association with citrullination, intestinal microbiome, or adipose tissue, which supports normal findings in synovial tissue in ACPA+ patients with arthralgia. The presence of ACPA is detectable even years before the first manifestation of RA. The pre-clinical phase of RA is the period preceding clinically apparent RA with ACPA contributing to the symptoms without subclinical inflammation. While the combination of ACPA and RF increases the risk of progression to RA by up to 10 times, increasing numbers of novel autoantibodies are to be investigated to contribute to the increased risk and pathogenesis of RA. With growing knowledge about the course of RA, new aspiration emerges to cure and even prevent RA, shifting the "window of opportunity" to the pre-clinical phases of RA. The clinical definition of individuals at risk of developing RA (clinically suspect arthralgia, CSA) makes it possible to unify these at-risk individuals' clinical characteristics for "preventive" treatment in ongoing clinical trials using mostly biological or conventional synthetic disease-modifying drugs. However, the combination of symptoms, laboratory, and imaging biomarkers may be the best approach to select the correct target at-risk population. The current review aims to explore different phases of RA and discuss the potential of (non)pharmacological intervention aiming to prevent RA.

Periodontal inflammation and distinct inflammatory profiles in saliva and gingival crevicular fluid (GCF) compared with serum and joints in rheumatoid arthritis patients

BACKGROUND

The association of periodontitis and Porphyromonas gingivalis (Pg) with rheumatoid arthritis (RA) is incompletely understood. To gain further insights, we evaluated periodontal status, oral, serum and joint inflammatory profiles, and Pg biomarkers in RA patients.

METHODS

In this cross-sectional study, we evaluated 33 patients with predominantly untreated new-onset RA, 20 healthy individuals (HIs), and 20 non-RA chronic periodontitis patients. Thirteen mediators (IFN-γ, IL-10, IL-17A, IL-6, IL-8, CXCL10, TNF-α, CXCL13, IL-23, MMP-1, MMP-3, MMP-8, MMP-9) were measured in serum, synovial fluid, saliva and gingival crevicular fluid (GCF) by multiplex immunoassay. Serum Pg IgG antibodies and subgingival Pg DNA were determined.

RESULTS

Most RA patients (91%) received routine dental care; only one currently smoked. Ten (30.3%) had periodontal health, 13 (39.4%) had gingivitis, and 10 (30.3%) had periodontitis. Th1 and innate immune responses predominated in serum. Many mediators were concentrated in joints, particularly IL-6, IL-8, and CXCL10. However, salivary and GCF profiles were more restricted, emphasizing neutrophilic inflammation (IL-8, MMP-8) and MMP-9. Compared with HI, most RA patients, regardless of periodontal status, had significantly elevated oral fluid levels of these mediators, with suppression of GCF IL-10, a pattern similar to non-RA periodontitis patients. Pg antibodies or DNA however were primarily associated with clinical periodontitis.

CONCLUSIONS

Despite routine dental care, RA patients often had inflammation in oral fluids, but inflammatory profiles differed from serum and joints. Neutrophilic inflammatory profiles in oral fluids, regardless of periodontal status, suggests that gingival tissues are a common, and often unrecognized, site of extra-articular inflammation in RA.

Molecular Strategies Underlying Porphyromonas gingivalis Virulence

The anaerobic Gram-negative bacterium Porphyromonas gingivalis is considered the keystone of periodontitis diseases, a set of inflammatory conditions that affects the tissues surrounding the teeth. In the recent years, the major virulence factors exploited by P. gingivalis have been identified and characterized, including a cocktail of toxins, mainly proteases called gingipains, which promote gingival tissue invasion. These effectors use the Sec pathway to cross the inner membrane and are then recruited and transported across the outer membrane by the type IX secretion system (T9SS). In P. gingivalis, most secreted effectors are attached to anionic lipopolysaccharides (A-LPS), and hence form a virulence coat at the cell surface. P. gingivalis produces additional virulence factors to evade host immune responses, such as capsular polysaccharide, fimbriae and outer membrane vesicles. In addition to periodontitis, it is proposed that this broad repertoire of virulence factors enable P. gingivalis to be involved in diverse human diseases such as rheumatoid arthritis, and neurodegenerative, Alzheimer, and cardiovascular disorders. Here, we review the major virulence determinants of P. gingivalis and discuss future directions to better understand their mechanisms of action.

An assessment of anti-citrullinated protein antibody in systemically healthy individuals with or without chronic periodontitis: A case-control study

Background:

Periodontitis has been implicated as a risk factor for rheumatoid arthritis (RA).

Aim:

This study aimed to assess the relationship between RA and chronic periodontitis (CP) by evaluating the serum levels of the anti citrullinated protein antibody (ACPA) which is a marker of RA in systemically healthy individuals with and without CP.

Materials and Methods:

This case–control study enrolled 40 systemically healthy individuals. Participants were divided into two groups, i.e., CP group Systemically healthy chronic periodontitis (CPSH) (n = 20) and control group Systemically healthy (SH) (n = 20), matched for age and gender. The CP patients were evaluated for periodontal parameters, namely probing pocket depth, clinical attachment loss, percentage of the site involved with attachment loss, and number of teeth present. A volume of 5 ml of venous blood was collected from both the groups and centrifuged; the separated serum was stored at − 70°C before being analyzed. Later, serum samples were tested for levels of ACPA in both the groups and compared.

Results:

The mean serum ACPA levels were higher in CPSH patients compared to SH (131.38 RU/ml vs. 34.54 RU/ml, P = 0.001), which was statistically highly significant. In addition, we found a significant elevation of serum ACPA levels in severe generalized CP patients compared to moderate generalized CP patients (175.47 RU/ml vs. 95.31 RU/ml, P = 0.001), and the difference was statistically highly significant.

Conclusion:

The results of the study confirmed that CP can be a risk factor for RA. Moreover, the severity of periodontitis appeared to be related to elevated serum levels of ACPA.

The Ubiquitin Proteasome System in Periodontal Disease: A Comprehensive Review

The turnover of intracellular proteins is a highly selective and regulated process. This process is responsible for avoiding injury and irreparable breakdown of cellular constituents. Its impairment disrupts cellular stability, integrity, and homeostasis. The ubiquitin-proteasome system (UPS) is responsible for this programmed degradation of most intracellular proteins. This process involves a cascade of enzymes that involves the ubiquitin conjugation to a target substrate protein, its recognition and degradation by the proteasome. The turn-over of intracellular proteins is a non-stop ubiquitous process that regulates a series of mechanisms, for instance transcription, translation, endocytosis. In addition, proteasome act by releasing peptides that may serve to other purposes, such as antigen presentation in immune actions and enzymatic flagging toward biosynthesis and gluconeogenesis. The role of the UPS impairment in periodontal diseases is gaining growing. This acquaintance might contribute to the development of novel therapeutic applications. Thus, this review focuses on the latest progresses on the role of the UPS and its signaling pathways in Periodontal Medicine. Furthermore, we discuss the potential of UPS-based drugs development to be used in periodontal disease therapy.

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/ ).

Levels of Anti-Citrullinated Protein Antibodies and Rheumatoid Factor, Including IgA Isotypes, and Articular Manifestations in Ulcerative Colitis and Crohn's Disease

Systemic presence of arthritis autoantibodies (AAb) is specific for rheumatoid arthritis (RA). AAb initiation might be triggered by chronic mucosal inflammation, such as in inflammatory bowel disease (IBD). We assessed the prevalence of anti-citrullinated protein antibodies (ACPA) and rheumatoid factor (RF) in ulcerative colitis (UC) and Crohn’s disease (CD) patients, with regard to the prevalence of joint complaints in AAb+ versus AAb− IBD patients. RA patients and healthy subjects (HC) served as controls. Serum was collected from 226 UC, 165 CD and 86 RA patients, and 36 HCs. One-hundred-and-ten UC (48.7%) and 76 CD (46.1%) patients were seropositive for at least one autoantibody, compared to 4 (13.9%) HCs and 81 (94.2%) RA patients. Eighty-three (37%) UC and 52 (32%) CD patients were seropositive for the anti-cyclic citrullinated protein antibody (anti-CCP2) of the immunoglobulin A type (IgA anti-CCP2), compared to 1 (2.8%) HC and 64 (74%) RA patients. RF of the immunoglobulin G type (IgG RF) and IgA RF seropositivity in UC and CD patients was comparable to HCs and low compared to RA patients. Arthralgia was reported by 34 (18.7%) UC and 50 (33.1%) CD patients, but presence of arthralgia was not increased in AAb+ patients. AAbs are frequently present in IBD patients, supporting the hypothesis that inflammation of intestinal mucosa induces low systemic levels of ACPA.

Hypothesis: Rheumatoid arthritis and periodontitis: A new possible link via prolactin hormone

Rheumatoid arthritis and periodontitis are two common chronic inflammatory diseases affecting human population worldwide. The association between the two conditions have been the focus of many researches, trying to explore the possible mechanisms underlying this association. Prolactin hormone, besides its known lactogenic effects acts as a cytokine secreted from various tissues other than the pituitary gland with multiple pleotropic actions in immunity and inflammation. Several data showed that prolactin levels are increased significantly in the synovial and periodontal tissues, and this increase is correlated with disease activity and tissue destruction. Our hypothesis suggests that local prolactin can represent a link between the two conditions. In this work, we suggest a possible mechanistic interactions, hypothesized to form a common path linking between rheumatoid arthritis, periodontitis and prolactin. This is because of the need to develop new treatment strategies for the most effective long term control of inflammation in both conditions.

Relationship between periodontitis and rheumatoid arthritis in Vietnamese patients

Objective: This study aimed to survey periodontal status of Vietnamese patients with rheumatoid arthritis (RA) and investigates the association between periodontitis and RA in these patients.Materials and methods: We conducted a cross-sectional descriptive study on 150 RA patients and another 150 patients with osteoarthritis (OA). RA was evaluated using the DAS28 disease activity score based on C-reactive protein levels (DAS28-CRP), disease activity classification, and serum levels of RA biomarkers. Periodontal status was determined using periodontal indices.Results: The proportion of periodontitis cases in the RA group was significantly higher than the OA group (67 and 28%, respectively). The rate of severe periodontitis observed in the RA group was also significantly higher than that in the OA group (22.7 and 8%, respectively). RA patients with periodontitis had higher DAS28-CRP scores, disease activity levels, ACPA positivity and higher serum levels of CRP and ACPAs. Periodontitis is associated with an increased risk for RA (odds ratio [OR]: 5.14, 95% confidence interval [CI]: 3.14 - 8.41) and with higher disease activity classification (OR: 2.7, 95% CI: 1.14 - 6.42).Conclusions: Vietnamese RA patients often presented with a more serious periodontal condition than OA patients. We observed an association between periodontal disease (PD) status and clinic symptoms and biochemical/immunological characteristics of RA.

Role of Infections in the Pathogenesis of Rheumatoid Arthritis: Focus on Mycobacteria

Rheumatoid arthritis (RA) is a systemic inflammatory autoimmune disease characterized by chronic erosive polyarthritis. A complex interaction between a favorable genetic background, and the presence of a specific immune response against a broad-spectrum of environmental factors seems to play a role in determining susceptibility to RA. Among different pathogens, mycobacteria (including Mycobacterium avium subspecies paratuberculosis, MAP), and Epstein–Barr virus (EBV), have extensively been proposed to promote specific cellular and humoral response in susceptible individuals, by activating pathways linked to RA development. In this review, we discuss the available experimental and clinical evidence on the interplay between mycobacterial and EBV infections, and the development of the immune dysregulation in RA.

Bacterial citrullinated epitopes generated by Porphyromonas gingivalis infection-a missing link for ACPA production

OBJECTIVES

Porphyromonas gingivalis (P.g.) is discussed to be involved in triggering self-reactive immune responses. The aim of this study was to investigate the autocitrullinated prokaryotic peptidylarginine deiminase (PPAD) from P.g. CH2007 (RACH2007-PPAD) from a rheumatoid arthritis (RA) patient and a synthetic citrullinated PPAD peptide (CPP) containing the main autocitrullination site as potential targets for antibody reactivity in RA and to analyse the possibility of citrullinating native human proteins by PPAD in the context of RA.

METHODS

Recombinant RACH2007-PPAD was cloned and expressed in Escherichia coli. Purified RACH2007-PPAD and its enzymatic activity was analysed using two-dimensional electrophoresis, mass spectrometry, immunoblot and ELISA. Autoantibody response to different modified proteins and peptides was recorded and bioinformatically evaluated.

RESULTS

RACH2007-PPAD was capable to citrullinate major RA autoantigens, such as fibrinogen, vimentin, hnRNP-A2/B1, histone H1 and multiple peptides, which identify a common RG/RGG consensus motif. 33% of RA patients (n=30) revealed increased reactivity for α-cit-RACH2007-PPAD before RA onset. 77% of RA patients (n=99) presented α-cit-specific signals to CPP amino acids 57-71 which were positively correlated to α-CCP2 antibody levels. Interestingly, 48% of the α-CPP-positives were rheumatoidfactor IgM/anti-citrullinated peptide/protein antibodies (ACPA)-negative. Anti-CPP and α-RACH2007-PPAD antibody levels increase with age. Protein macroarrays that were citrullinated by RACH2007-PPAD and screened with RA patient sera (n=6) and controls (n=4) uncovered 16 RACH2007-PPAD citrullinated RA autoantigens and 9 autoantigens associated with lung diseases. We showed that the α-CPP response could be an important determinant in parenchymal changes in the lung at the time of RA diagnosis (n=106; p=0.018).

CONCLUSIONS

RACH2007-PPAD induced internal citrullination of major RA autoantigens. Anti-RACH2007-PPAD correlates with ACPA levels and interstitial lung disease autoantigen reactivity, supporting an infection-based concept for induction of ACPAs via enzymatic mimicry.

Novel and known periodontal pathogens residing in gingival crevicular fluid are associated with rheumatoid arthritis

Background

Periodontitis is a suspected environmental risk factor for the development of rheumatoid arthritis (RA). However, correlation mechanisms between the two pathologies remain elusive. This study examined potential correlations between detached subgingival bacteria collected in gingival crevicular fluid (GCF) and RA parameters.

Methods

RA patients (n = 52, F:M = 40:12), patients with Behcet's disease (BD, n = 40, F:M = 29:11) as another systemic inflammatory disease were studied along with a systemically healthy control group (HC, n = 57, F:M = 40:17). All participants were non‐smokers. Full mouth periodontal parameters were recorded. RA activity was assessed using the 28‐joint Disease Activity Score (DAS‐28). Rheumatoid factors (RFs)‐IgM and ‐IgA were measured by ELISA. GCF samples were investigated by means of fluorescent in situ hybridization for 10 different bacterial taxa.

Results

The taxa TM7, Synergistetes cluster B, Leptotrichia, Megasphaera, Anaeroglobus geminatus, and Tannerella forsythia displayed significantly differential abundances between the groups. Whereas abundances of Megasphaera and A. geminatus were significantly increased in the RA group, only Porphyromonas gingivalis displayed significant correlations with plaque scores, bleeding on probing, and RF‐IgA. RA patients displaying RF‐IgA levels >75 IU/mL exhibited five‐fold more abundant P. gingivalis levels than patients below the threshold. This association with RF‐IgA levels appeared even more pronounced, by six‐fold more P. gingivalis (P = 0.025), in patients with a DAS‐28 score >3.2, indicative of moderate/very active RA.

Conclusions

Unattached GCF bacteria may mediate the association between periodontitis and RA, and monitoring the bacterial composition of GCF might inform on RA activity. The role of newly identified bacterial taxa in RA warrants further investigations.

Troublesome friends within us: the role of gut microbiota on rheumatoid arthritis etiopathogenesis and its clinical and therapeutic relevance

The role of gut microbiota on immune regulation and the development of autoimmune diseases such as rheumatoid arthritis (RA) is an emerging research topic. Multiple studies have demonstrated alterations on gut microbiota composition and/or function (referred to as dysbiosis) both in early and established RA patients. Still, research delineating the molecular mechanisms by which gut microorganisms induce the loss of immune tolerance or contribute to disease progression is scarce. Available data indicate that gut microbiota alterations are involved in RA autoimmune response by several mechanisms including the post-translational modification of host proteins, molecular mimicry between bacterial and host epitopes, activation of immune system and polarization toward inflammatory phenotypes, as well as induction of intestinal permeability. Therefore, in this review we analyze recent clinical and molecular evidence linking gut microbiota with the etiopathogenesis of RA. The potential of the gut microbiota as a diagnostic or severity biomarker is discussed, as well as the opportunity areas for the development of complementary therapeutic strategies based on the modulation of gut microbiota in the rheumatic patient.

Localisation of citrullinated and carbamylated proteins in inflamed gingival tissues from rheumatoid arthritis patients

OBJECTIVES

It has been proposed that citrullination and carbamylation occur in the inflamed periodontium and could be the plausible mechanisms for the generation of antigens involved in the development and progression of RA. The purpose of this study was to determine the presence and location of citrullinated and carbamylated proteins in the gingival tissues and compare their abundance in periodontitis (PD) patients with or without RA.

MATERIALS AND METHODS

Gingival tissue samples of healthy (n = 5), PD with RA (n = 5) and PD without RA (n = 5) were collected. Specimens were formalin fixed, paraffin embedded and sectioned at 4 μm. The tissue sections were analysed for the presence of citrullinated and carbamylated proteins by immunohistochemistry. Semi-quantitative analysis was performed to quantify and compare the protein abundance between groups.

RESULTS

The number of cells containing citrullinated and carbamylated proteins with higher intensity was markedly increased in gingival tissues from PD with or without RA in comparison with healthy controls.

CONCLUSION

Inflamed gingival tissue is a potential source of citrullinated and carbamylated proteins other than synovial tissues. The extent to which the local accumulation of these proteins contributes to the pathogenesis of RA needs further elucidation.

CLINICAL RELEVANCE

If PD is a potential source of post-translationally modified proteins, untreated PD should not be taken lightly in the context of RA. Hence, addressing gingival inflammation should be viewed as an important preventive measure in the general population not only for the progression of periodontal disease but also reducing the risk of developing extra-oral comorbidities.