Antibodies to porphyromonas gingivalis are associated with anticitrullinated protein antibodies in patients with rheumatoid arthritis and their relatives

Oral microbiota imbalance: A predisposing factor for Henoch-Schönlein Purpura in children

Oral microecological dysregulation has been shown to be associated with various immune system disorders. Henoch-schonlein purpura (HSP) is an autoimmune small vessel inflammatory disease in children of uncertain etiology, and studies have suggested that streptococcal infection may be an influential factor in its development. However, the relationship between oral microecological dysregulation and HSP has not been clearly studied so far. In this study, an epidemiological survey on the oral health status of children with HSP was investigated in this paper, and collected dental plaque from four groups of children for 16SrDNA high-throughput sequencing to analyze the composition and changes of oral microbial diversity among different groups. The results showed that the oral health status of children with HSP was poor, except for the incidence of caries in the 5-year-old group, the caries rate and dmfs/DMFS in the 3,4 and 5-year-old groups were higher than the same age in the fourth Chinese Oral Health Epidemiological Survey. Moreover, the development of HSP is accompanied by disturbances in the oral microbiota; a decrease in the number of Firmicutes which producing butyric acid may be closely associated with the development of HSP; changes in the abundance of Streptococcus and Neisseria may be a risk factor for the development of HSP.

Application of Salivary Alpha-1 Antitrypsin in the Diagnosis of Rheumatoid Arthritis: A Pilot Study

Background and Objective: Rheumatoid arthritis (RA) is an autoimmune disease in which joints are gradually destroyed. Early diagnosis and treatment before joint deformation or destruction is important. The detection of novel RA biomarkers in saliva may facilitate early detection of RA before disease onset. This study aimed to evaluate salivary concentration of α1-antitrypsin (A1AT) in healthy patients and those with RA, and to assess the diagnostic value of salivary A1AT. Materials and Methods: In total, 80 participants were included: 20 healthy participants, and 60 patients with RA. Saliva and serum samples were obtained from all the patients. Levels of A1AT and cytokines, including interleukin-1 beta (IL-1β), IL-6, and IL-10 in saliva and serum, were evaluated using an enzyme-linked immunosorbent assay kit and Luminex assay. Data were analyzed using SPSS for Windows. Results: There was a higher level of A1AT in the saliva of patients with RA (median: 2388.66 ng/mL) than that in healthy controls (1579.06 ng/mL). There was a positive mild-to-moderate accuracy (area under the curve: 0.57-0.85) of A1AT in saliva to diagnose RA. The cut-off level (ng/mL) of A1AT in saliva for detecting RA was 1689.0. Conclusions: The obtained data can promote the application of the measurements of A1AT in saliva to diagnose RA.

Presence of periodontal disease and the incidence of inflammatory arthritides in the general population: data from the UK Biobank

OBJECTIVES

To investigate the association between periodontal disease and the development of inflammatory arthritides in the general population.

METHODS

In total, 489 125 participants from the UK Biobank without a previous history of RA, AS and PsA were enrolled. The primary outcome was the incidence of inflammatory arthritides, which was a composite of RA, AS and PsA according to the presence of periodontal disease based on self-reported oral health indicators. Multivariate Cox proportional hazard regression analyses using four different models were performed to assess the association between periodontal disease and inflammatory arthritides development.

RESULTS

In all, 86 905 and 402 220 individuals were categorized as with and without periodontal disease, respectively. Cox hazard analysis indicated that the presence of periodontal disease was an independent predictor of the occurrence of composite outcomes of inflammatory arthritides, which was also consistent for RA and AS. Significant associations were found to be consistent in the four Cox models and were replicated even when different criteria were used to define periodontal disease. Subgroup analyses indicated that periodontal disease was associated with an increased RA risk in those aged <60 years, and this risk was persistent for both male and female patients and for patients with seropositive/seronegative RA.

CONCLUSION

Self-reported periodontal disease is associated with inflammatory arthritides incidence in participants included in the UK Biobank, particularly for RA and AS. Higher clinical attention and optimal dental care in patients with signs of periodontal disease may be recommended for early disease detection and for reducing this risk.

Association between periodontal disease and malignant soft tissue sarcomas

OBJECTIVE

Malignant soft tissue sarcoma (MSTS) is a rare disease, but is seen in patients undergoing orthopedic surgery. Although the association of periodontal disease with various cancers occurring in the oral cavity, gastrointestinal tract, lungs, and prostate, has been reported, the association between periodontal disease and MSTS remains unclear. This study investigated the association between periodontal disease and MSTS in patients undergoing orthopedic surgery.

SUBJECTS AND METHODS

One hundred fifteen patients who underwent orthopedic surgery between 2017 and 2021 were retrospectively enrolled (mean age = 66.8 ± 10.7 years). The patient background was adjusted by the propensity score (PS). Subsequently, the association of periodontal disease with MSTS was analyzed using PS inverse probability of treatment weighting (IPTW). Periodontal status was determined by evaluating the periodontal inflamed surface area, which was calculated by measuring the periodontal probing pocket depth and detecting bleeding on probing.

RESULTS

Multivariate logistic regression analysis after adjustment by the PS showed that severe periodontitis was significantly associated with MSTS (odds ratio 2.81, p = 0.04). Furthermore, IPTW showed that severe periodontitis was significantly associated with MSTS (odds ratio 3.21, p = 0.01).

CONCLUSION

The results indicate an association between periodontal inflammation and MSTS.

Peptoniphilus gorbachii alleviates collagen-induced arthritis in mice by improving intestinal homeostasis and immune regulation

Introduction

The intricate connection between gut microbiota and rheumatoid arthritis (RA) pathogenesis has gained prominence, although the specific microbial species contributing to RA development remain largely unknown. Recent studies have sought to comprehensively explore alterations in the human microbiome, focusing on identifying disease-related microbial species through blood analysis. Consequently, this study aimed to identify RA-associated microbial species using a serum microbial array system and to investigate the efficacy and underlying mechanisms of potential microbial species for RA treatment.

Methods

Serum immunoglobulin M levels against 384 intestinal microbial species were assessed using a microbial microarray in patients with RA and healthy individuals. We investigated the therapeutic potential of the identified microbial candidate regarding arthritis development, immune responses, gut barrier function, and gut microbiome using a collagen-induced arthritis (CIA) mouse model.

Results

Our findings revealed significant alterations in antibody levels against 36 microbial species in patients with RA compared to healthy individuals. Notably, the antibody levels against Peptoniphilus gorbachii (PG) were decreased in patients with RA and exhibited an inverse correlation with RA disease activity. In vitro experiments demonstrated that PG produced acetate and butyrate, while exhibiting anti-inflammatory properties. In CIA mice, PG administration suppressed arthritis symptoms, reduced the accumulation of inflammatory monocytes in the mesenteric lymph nodes, and downregulated gene expression of pro-inflammatory cytokines in the ileum. Additionally, PG supplementation restored intestinal barrier integrity and partially resolved gut microbial dysbiosis in CIA mice. The fecal microbiota in PG-treated mice corresponded to improved intestinal barrier integrity and reduced inflammatory responses.

Conclusion

This study highlights the potential of serum-based detection of anti-microbial antibodies to identify microbial targets at the species level for RA treatment. Moreover, our findings suggest that PG, identified through the microbial microarray analysis, holds therapeutic potential for RA by restoring intestinal barrier integrity and suppressing the immunologic response associated with RA.

Enzyme targeted delivery of sivelestat loaded nanomicelle inhibits arthritic severity in experimental arthritis

AIMS

Rheumatoid arthritis (RA) is chronic inflammatory disorder mainly affects the lining of articular cartilage of synovial joints characterized by severe inflammation and joint damage. The expression of proteolytic enzymes like MMP-2 and Neutrophil Elastase (NE) worsens the RA condition. To address this concern, we have synthesized dual enzyme targeted chlorotoxin conjugated nanomicelles loaded with sivelestat as broad spectrum treatment for RA.

MATERIALS AND METHODS

Conjugation of the chlorotoxin over nanomicelle and incorporation of sivelestat in nanomicelle provide it dual targeting potential. The sivelestat loaded nanomicelle (SLM) evaluated for the drug release and in-vitro cytocompatibility. Further, investigated its in-vivo anti-arthritic potential on collagen-induced arthritis in wistar rats.

KEY FINDINGS

The microscopic observation of SLM showed spherical ball like appearance with size ranging from 190 to 230 nm. SLM showed good drug loading and encapsulation efficiency along with no cytotoxicity against healthy cell lines. In-vivo therapeutic assessment on collagen induced arthritis rat model showed potential chondroprotection. The microscopic visualization of articular cartilage by staining showed that it restores the cartilage integrity and lowers the expression of pro-inflammatory enzymes showed by Immunohistochemistry and Immunofluorescence. We observed that, it restrain the mediators of synovial inflammation by simultaneous inhibition of the proteolytic enzymes involved in swelling, cartilage destruction and joint damage which provides strong chondroprotection.

SIGNIFICANCE

We report that significant alleviation of inflammation and inhibition of proteolytic enzymes together might provide enhanced potential for the treatment and management of RA.

Periodontal health status, Porphyromonas gingivalis and anti-cyclic citrullinated peptide antibodies among rheumatoid arthritis patients

Porphyromonas gingivalis (P. gingivalis) is the primary periodontal pathogen involved in protein citrullination, which triggers the production of anti-cyclic citrullinated peptide (anti-CCP) antibodies, exacerbating rheumatoid arthritis (RA). This study aims to evaluate the amount of P. gingivalis and its association with anti-CCP antibodies in RA patients with periodontitis. This cross-sectional study involves 100 RA patients with a mean age of 52.36 (SD 13.90) years. Smokers and patients with other uncontrolled systemic diseases were excluded. Disease Activity Score-28 (DAS-28) was used to determine RA disease severity. Periodontal parameters were examined to determine periodontal status. Subsequently, plaque samples were collected from the subgingival periodontal pocket for assessment of P. gingivalis bacterial load using the loop-mediated isothermal amplification method. Blood samples (5 ml) were obtained from all participants to analyse anti-CCP antibody levels. Data was analysed by using SPSS version 24.0. Most participants were female (85.0%) and had low RA disease severity (62%). The mean RA disease duration was 7.77 (SD 6.3) years, with a mean DAS-28 of 3.17 (SD 1.0). Forty-seven per cent of participants had periodontitis, but all periodontal parameters were not associated with RA disease activity (P = 0.38). P. gingivalis bacterial load ranged from 10 to 109 copies/μl. Fifty-five per cent of the collected samples showed positive anti-CCP antibody levels, but no significant association was observed with the P. gingivalis bacterial load (P = 0.58). Considering the study's limitations, although periodontitis is prevalent among RA patients, there is a lack of association between P. gingivalis bacterial load and anti-CCP antibody levels, which should be investigated further.

Increased risk of periodontitis in patients with rheumatoid arthritis: A nationwide register study in Norway

AIM

To investigate the risk of periodontitis in rheumatoid arthritis (RA) patients in a nationwide register-based study.

MATERIALS AND METHODS

Patients and controls were defined using ICD-10 codes registered in the Norwegian Patient Registry (NPR), from 2011 to 2017. The 324,232 included subjects had at least one registered diagnostic code for RA (33,040 patients) or diagnostic codes for non-osteoporotic fractures or hip or knee replacement due to osteoarthritis (controls). The outcome was periodontitis, defined by codes for periodontal treatment from the Norwegian Control and Payment of Health Reimbursements Database (KUHR). Hazard ratios (HRs) were calculated for periodontitis in RA patients compared to controls. Generalized additive model in Cox regressions was estimated to visualize periodontitis occurrences as a function of number of RA visits.

RESULTS

The risk of periodontitis increased with increasing number of RA visits. RA patients having 10 or more visits during the 7-year period had a 50% increased risk of periodontitis compared to controls (HR = 1.48, 95% confidence interval [CI]: 1.39-1.59); also, in patients with assumed new RA, an even higher risk estimate was seen (HR = 1.82, 95% CI: 1.53-2.17).

CONCLUSIONS

In this register-based study in which periodontal treatment was used as a surrogate marker for periodontitis, we found an increased risk of periodontitis in RA patients, particularly those with active disease and new RA.

Anti-citrullinated protein antibodies as biomarkers in rheumatoid arthritis

INTRODUCTION

The serological biomarker anti-citrullinated protein antibodies (ACPAs) may have several functions but is especially important for the diagnosis of rheumatoid arthritis (RA) along with clinical symptoms.

AREAS COVERED

This review provides an overview of ACPAs, which are useful in RA diagnostics and may improve our understanding of disease etiology. PubMed was searched with combinations of words related to antibodies recognizing epitopes containing the post-translationally modified amino acid citrulline in combination with rheumatoid arthritis; cyclic citrullinated peptide, CCP, anti-CCP, anti-citrullinated protein antibodies, ACPA, citrullination, peptide/protein arginine deiminase, PAD, filaggrin, vimentin, keratin, collagen, perinuclear factor, EBNA1, EBNA2, and others. From this search, we made a qualitative extract of publications relevant to the discovery, characterization, and clinical use of these antibodies in relation to RA. We highlight significant findings and identify areas for improvement.

EXPERT OPINION

ACPAs have high diagnostic sensitivity and specificity for RA and recognize citrullinated epitopes from several proteins. The best-performing single epitope originates from Epstein-Barr Virus nuclear antigen 2 and contains a central Cit-Gly motif, which is recognized by ACPAS when located in a flexible peptide structure. In addition, ACPAs may also have prognostic value, especially in relation to early treatment, although ACPAs' main function is to aid in the diagnosis of RA.

The Integral Role of Diets Including Natural Products to Manage Rheumatoid Arthritis: A Narrative Review

Genetic and environmental factors including lifestyle are thought to play a key role in the pathophysiology of rheumatoid arthritis (RA). There is evidence that diet can enhance the inflammatory response in genetically predisposed individuals. On the other hand, certain types of diets can alleviate RA symptoms due to their anti-inflammatory and antioxidant activities. Also, natural compounds with potential effectiveness in RA management belong to different chemical classes such as flavonoids, polyphenols, carotenoids, and alkaloids with their antioxidant characteristics as well as probiotics. The nutritional approaches to prevent or extenuate the disease progress were examined in this narrative review which was conducted using the PubMed, ScienceDirect and Google Scholar databases and conforms to the Scale for the Assessment of Narrative Review Articles (SANRA) guidelines. Mediterranean and vegan diets equally have been shown to exhibit positive effects on RA as the consumption of dietary fiber, antioxidants and anti-inflammatory compounds from fruits, vegetables, grains, nuts, and seeds are high. Whereas Mediterranean diet additionally includes beneficial nutrients of animal origin such as omega-3 polyunsaturated fatty acids from fish and seafood, patients on vegan diet need to be monitored closely for intake of all critical nutrients. Certain calorie restrictions and intermittent fasting diets have been shown to benefit RA patients although there is an obvious need for further studies to establish solid evidence-based recommendations and guidelines. The research data available strongly suggest that dietary approaches with anti-inflammatory properties may help delay the onset of RA and/or improve symptoms and thus nutrition should be routinely addressed to facilitate management of the disease.

A Review on Saliva-Based Health Diagnostics: Biomarker Selection and Future Directions

The human body has a unique way of saying when something is wrong with it. The molecules in the body fluids can be helpful in the early detection of diseases by enabling health and preventing disease progression. These biomarkers enabling better healthcare are becoming an extensive area of research interest. Biosensors that detect these biomarkers are becoming the future, especially Point Of Care (POC) biosensors that remove the need to be physically present in the hospital. Detection of complex and systemic diseases using biosensors has a long way to go. Saliva-based biosensors are gaining attention among body fluids due to their non-invasive collection and ability to detect periodontal disease and identify systemic diseases. The possibility of saliva-based diagnostic biosensors has gained much publicity, with companies sending home kits for ancestry prediction. Saliva-based testing for covid 19 has revealed effective clinical use and relevance of the economic collection. Based on universal biomarkers, the detection of systemic diseases is a booming research arena. Lots of research on saliva-based biosensors is available, but it still poses challenges and limitations as POC devices. This review paper talks about the relevance of saliva and its usefulness as a biosensor. Also, it has recommendations that need to be considered to enable it as a possible diagnostic tool.

Graphical Abstract

The role of the oral microbiome in obesity and metabolic disease: potential systemic implications and effects on taste perception

Obesity and its metabolic sequelae still comprise a challenge when it comes to understanding mechanisms, which drive these pandemic diseases. The human microbiome as a potential key player has attracted the attention of broader research for the past decade. Most of it focused on the gut microbiome while the oral microbiome has received less attention. As the second largest niche, the oral microbiome is associated with a multitude of mechanisms, which are potentially involved in the complex etiology of obesity and associated metabolic diseases. These mechanisms include local effects of oral bacteria on taste perception and subsequent food preference as well as systemic effects on adipose tissue function, the gut microbiome and systemic inflammation. This review summarizes a growing body of research, pointing towards a more prominent role of the oral microbiome in obesity and associated metabolic diseases than expected. Ultimately, our knowledge on the oral microbiome may support the development of new patient oriented therapeutic approaches inevitable to relieve the health burden of metabolic diseases and to reach long-term benefits in patients´ lives.

The Interaction Effect of Anti-RgpA and Anti-PPAD Antibody Titers: An Indicator for Rheumatoid Arthritis Diagnosis

Porphyromonas gingivalis secretes virulence factors like Arg-gingipains and peptidyl arginine deiminase (PPAD), that are associated with rheumatoid arthritis (RA) pathogenesis. However, there is no information regarding the antibody titers for these bacterial enzymes as systemic indicators or biomarkers in RA. In this cross-sectional study, 255 individuals were evaluated: 143 were diagnosed with RA, and 112 were without RA. Logistic regression models adjusted for age, sex, basal metabolic index, smoking, and periodontitis severity were used to evaluate the association of RA with rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPAs), erythrocyte sedimentation rate, high sensitivity C-reactive protein, anti-RgpA, anti-PPAD, and double positive anti-RgpA/anti-PPAD. It was found that RF (odds ratio [OR] 10.6; 95% confidence interval [CI] 4.4-25), ACPAs (OR 13.7; 95% CI 5.1-35), and anti-RgpA/anti-PPAD double positivity (OR 6.63; 95% CI 1.61-27) were associated with RA diagnoses. Anti-RgpA was also associated with RA (OR 4.09; 95% CI 1.2-13.9). The combination of anti-RgpA/anti-PPAD showed a high specificity of 93.7% and 82.5% PPV in identifying individuals with RA. RgpA antibodies were associated with the periodontal inflammatory index in RA individuals (p < 0.05). The double positivity of the anti-RgpA/anti-PPAD antibodies enhanced the diagnosis of RA. Therefore, RgpA antibodies and anti-RgpA/anti-PPAD may be biomarkers for RA.

Immune dysregulation and pathogenic pathways mediated by common infections in rheumatoid arthritis

Rheumatoid arthritis (RA) is one of the world's most prevalent inflammatory autoimmune diseases, affecting between 0.4 and 1.3% of the population. The susceptibility to RA appears to be influenced by a complex interaction between a favorable genetic background and the existence of a specific immune reaction against a wide range of environmental variables. Among the known environmental variables, infections are believed to have a significant role in promoting the formation of autoimmune disorders, which are frequently caused by specific microorganisms. Infections have been linked to RA in recent medical studies. In this study, we selected the most prevalent infections associated with RA from the literature and described the data confirming their pathogenic role in RA. Our investigation included Mycobacterium, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Proteus mirabilis, Epstein-Barr virus, parvovirus, and Prevotella copri.

Anti-Citrullinated Peptide Antibodies Control Oral Porphyromonas and Aggregatibacter species in Patients with Rheumatoid Arthritis

Oral microbiome changes take place at the initiation of rheumatoid arthritis (RA); however, questions remain regarding the oral microbiome at pre-RA stages in individuals with clinically suspect arthralgia (CSA). Two cross-sectional cohorts were selected including 84 Tatarstan women (15 early-RA as compared to individuals with CSA ranging from CSA = 0 [n = 22], CSA = 1 [n = 19], CSA = 2 [n = 11], and CSA ≥ 3 [n = 17]) and 42 women with established RA (median: 5 years from diagnosis [IQ: 2–11]). Amplicon sequence variants (ASVs) obtained from oral samples (16S rRNA) were analyzed for alpha and beta diversity along with the abundance at the genus level. A decrease in oral Porphyromonas sp. is observed in ACPA-positive individuals, and this predominates in early-RA patients as compared to non-RA individuals irrespective of their CSA score. In the RA-established cohort, Porphyromonas sp. and Aggregatibacter sp. reductions were associated with elevated ACPA levels. In contrast, no associations were reported when considering individual, genetic and clinical RA-associated factors. Oral microbiome changes related to the genera implicated in post-translational citrullination (Porphyromonas sp. and Aggregatibacter sp.) characterized RA patients with elevated ACPA levels, which supports that the role of ACPA in controlling the oral microbiome needs further evaluation.

Periodontitis and implant complications in diabetes

Epidemiologic evidence indicates that periodontitis is more frequent in patients with uncontrolled diabetes mellitus than in healthy controls, suggesting that it could be considered the "sixth complication" of diabetes. Actually, diabetes mellitus and periodontitis are two extraordinarily prevalent chronic diseases that share a number of comorbidities all converging toward an increased risk of cardiovascular disease. Periodontal treatment has recently been shown to have the potential to improve the metabolic control of diabetes, although long-term studies are lacking. Uncontrolled diabetes also seems to affect the response to periodontal treatment, as well as the risk to develop peri-implant diseases. Mechanisms of associations between diabetes mellitus and periodontal disease include the release of advanced glycation end products as a result of hyperglycemia and a range of shared predisposing factors of genetic, microbial, and lifestyle nature. This review discusses the evidence for the risk of periodontal and peri-implant disease in diabetic patients and the potential role of the dental professional in the diabetes-periodontal interface.

Pros and cons of causative association between periodontitis and rheumatoid arthritis

Research in recent decades has brought significant advancements in understanding of the molecular basis of the etiology of autoimmune diseases, including rheumatoid arthritis, a common systemic disease in which an inappropriate or inadequate immune response to environmental challenges leads to joint destruction. Recent studies have indicated that the classical viewpoint of the immunological processes underpinning the pathobiology of rheumatoid arthritis is restricted and needs to be expanded to include a more holistic and interdisciplinary approach incorporating bacteria-induced inflammatory reactions as an important pathway in rheumatoid arthritis etiology. Here, we discuss in detail data showing the clinical and molecular association of rheumatoid arthritis development with periodontal diseases. We also describe the unique role of periopathogens, which have been proposed to be crucial in the initiation and progression of this autoimmune pathological disorder.

Periodontitis in First Degree-Relatives of Individuals With Rheumatoid Arthritis: A Short Narrative Review

Periodontal disease (PD) and rheumatoid arthritis (RA) are chronic inflammatory diseases with a bi-directional relationship. Both share common genetic and environmental risk factors and result in the progressive destruction of bone and connective tissue. First degree relatives of patients with RA (FDR-RA) are one of the at-risk populations for RA. The etiopathogenic mechanisms of their susceptibility are currently being explored, focusing mostly on the role of anti–cyclic citrullinated protein/ peptide antibodies (ACPA) in triggering RA. Oral microbiota and their relation with oral health has been suggested as a factor influencing the risk of the FDR-RA developing RA. In particular, compromised periodontal status often correlates with ACPA seropositivity in FDR-RA. The presence of periodontal pathogens such as Porphyromonas gingivalis, in oral microbiota has been proposed to increase the risk of developing RA through its uniquely expressed peptidyl arginine deiminase (PPAD), capable of citrullinating both host and bacterial peptides. Aggregatibacter actinomycetemcomitans and its leukotoxin A (LtxA), also induces hypercitrullination in host neutrophils. Common risk factors of periodontitis and RA such as genetic predisposition, smoking, higher local and systemic inflammatory burden, are discussed in the literature. Based on those mechanisms periodontal disease seems to be presented as one of the factors triggering RA in FDR-RA. Larger studies evaluating all the potential mechanisms linking RA and periodontitis are needed in FDR-RA to confirm that periodontal disease should be considered in the screening of FDR-RA.

Relation between anti-Porphyromonas gingivalis antibody titers and HLA-DRB1 neutral alleles in individuals with rheumatoid arthritis

OBJECTIVE

This study aimed to determine the relation between titres of anti-Porphyromonas gingivalis (P. gingivalis) antibody and rheumatoid arthritis (RA) HLA-DRB1 susceptibility region associated with shared epitope (SE) using the Gregersen's and de Vries's classification methods.

MATERIAL AND METHODS

In this cross-sectional study, results of immunoglobulin G1 (IgG1) and immunoglobulin G2 (IgG2) anti-P. gingivalis antibodies, anti-citrullinated protein antibodies (ACPA), diagnosis for RA, and periodontal disease (PD), and a genetic study of the HLA DRB1 region were obtained from 50 patients with RA and 50 control individuals.

RESULTS

Anti-P. gingivalis antibody levels and PD parameters were similar in control and RA groups. Anti-P. gingivalis antibodies were not associated with SE or ACPA. There was no association between ACPA and SE. However, de Vries' classification in RA patients revealed an association between the HLA DRB1 neutral alleles and higher titres of anti-P. gingivalis antibodies as follows: IgG1 anti-P. gingivalis ≥ 1:400 (p = .039); IgG2 anti-P. gingivalis ≥ 1:400 with neutral/neutral genotype (N/N), being exclusive for RA (p = .008); and IgG2 anti-P. gingivalis ≥ 1:200 and N/N (p = .016).

CONCLUSIONS

Although no association was found between SE and anti-P. gingivalis antibodies; according to the de Vries' classification, there was an existing association between HLA DRB1 neutral alleles, with high titres of IgG anti-P.gingivalis antibodies for RA, focussing on novel associations between P.gingivalis and RA.

Autoantibodies in Rheumatoid Arthritis: Historical Background and Novel Findings

Autoantibodies represent a hallmark of rheumatoid arthritis (RA), with the rheumatoid factor (RF) and antibodies against citrullinated proteins (ACPA) being the most acknowledged ones. RA patients who are positive for RF and/or ACPA ("seropositive") in general display a different etiology and disease course compared to so-called "seronegative" patients. Still, the seronegative patient population is very heterogeneous and not well characterized. Due to the identification of new autoantibodies and advancements in the diagnosis of rheumatic diseases in the last years, the group of seronegative patients is constantly shrinking. Aside from antibodies towards various post-translational modifications, recent studies describe autoantibodies targeting some native proteins, further broadening the spectrum of recognized antigens. Next to the detection of new autoantibody groups, much research has been done to answer the question if and how autoantibodies contribute to the pathogenesis of RA. Since autoantibodies can be detected years prior to RA onset, it is a matter of debate whether their presence alone is sufficient to trigger the disease. Nevertheless, there is gathering evidence of direct autoantibody effector functions, such as stimulation of osteoclastogenesis and synovial fibroblast migration in in vitro experiments. In addition, autoantibody positive patients display a worse clinical course and stronger radiographic progression. In this review, we discuss current findings regarding different autoantibody types, the underlying disease-driving mechanisms, the role of Fab and Fc glycosylation and clinical implications.

Association of Bitter Taste Receptor T2R38 Polymorphisms, Oral Microbiota, and Rheumatoid Arthritis

The association of taste genetics and the oral microbiome in autoimmune diseases such as rheumatoid arthritis (RA) has not been reported. We explored a novel oral mucosal innate immune pathway involving the bitter taste G protein-coupled receptor T2R38. This case–control study aimed to evaluate whether T2R38 polymorphisms associate with the buccal microbial composition in RA. Genomic DNA was obtained from buccal swabs of 35 RA patients and 64 non-RA controls. TAS2R38 genotypes were determined by Sanger sequencing. The buccal microbiome was assessed by Illumina MiSeq sequencing of the V4-16S rRNA gene. Bacterial community differences were analyzed with alpha and beta diversity measures. Linear discriminant analysis effect size identified taxa discriminating between RA versus non-RA and across TAS2R38 genotypes. TAS2R38 genotype frequency was similar between RA and non-RA controls (PAV/PAV; PAV/AVI; AVI/AVI: RA 42.9%; 45.7%; 11.4% versus controls 32.8%; 48.4%; 18.8%, chi-square (2, N = 99) = 2.1, p = 0.35). The relative abundance of Porphyromonas, among others, differed between RA and non-RA controls. The relative abundance of several bacterial species also differed across TAS2R38 genotypes. These findings suggest an association between T2R38 polymorphisms and RA buccal microbial composition. However, further research is needed to understand the impact of T2R38 in oral health and RA development.

Periodontal disease in seropositive rheumatoid arthritis: scoping review of the epidemiological evidence

The link between periodontal disease (PD) and rheumatoid arthritis (RA) has been hypothesized to lie in the anti-cyclic citrullinated protein antibody (ACPA) molecules present in seropositive RA. This review aimed to discuss how RA and specifically ACPA-positive RA link to PD, and appraise the epidemiological evidence on the relationship between ACPA-positive RA and PD. Articles were searched following the PRISMA guideline across the MEDLINE, Web of Science, Scopus and Cochrane Library databases. A total of 21 articles met the inclusion criteria of reporting the epidemiological data on the different ACPA status of the subjects with RA and PD (or periodontitis) parameters. A discrepancy is noted in the epidemiological evidence on the difference in the prevalence and severity of PD between ACPA-positive and ACPA-negative RA patients. Although the link between RA and PD is mostly discussed in terms of ACPA, reports on the different manifestations of PD between the two RA subsets remains inconclusive.

Oral infection with a periodontal pathogen alters oral and gut microbiomes

Periodontal disease, an inflammatory bone disease of the oral cavity, affects more than 50% of the United States population over the age of 30. The Gram-negative, anaerobic bacterium Porphyromonas gingivalis, the etiological agent of periodontal disease, is known to induce dysbiosis of the oral microbiome while promoting inflammatory bone loss. We have recently reported that P. gingivalis can also alter the gut microbiota of mice prone to develop inflammatory atherosclerosis. However, it is still unknown whether P. gingivalis induces similar changes to the gut microbiome as it does to oral microbiome. In this study, we demonstrate that P. gingivalis infection increases the diversity of the oral microbiome, allowing for colonization of potentially opportunistic species in the oral microbiome and overgrowth of commensal species in both the oral and gut microbiomes. Since periodontal disease treatment in humans typically involves antibiotic treatment, we also examined the combined effect of P. gingivalis infection on mice pretreated with oral antibiotics. By correlating the oral and cecal microbiota of P. gingivalis-infected mice fed a normal chow diet, we identified blooms of the Gram-negative genera Barnesiella and Bacteroides and imbalances of mucin-degrading bacteria. These disrupted community structures were predicted to have increased detrimental functional capacities including increased flavonoid degradation and l-histidine fermentation. Though antibiotic pretreatment (without P. gingivlais) had a dominant impact on the cecal microbiome, P. gingivalis infection of mice with or without antibiotic pretreatment increased the abundance of the phylum Firmicutes and the Porphyromonadaceae family in the cecum. Collectively, our study demonstrates that P. gingivalis oral infection disrupted the oral and cecal microbiomes of otherwise unperturbed mice, altering their community membership and functional potential.

Progress in Oral Microbiome Related to Oral and Systemic Diseases: An Update

The human oral microbiome refers to an ecological community of symbiotic and pathogenic microorganisms found in the oral cavity. The oral cavity is an environment that provides various biological niches, such as the teeth, tongue, and oral mucosa. The oral cavity is the gateway between the external environment and the human body, maintaining oral homeostasis, protecting the mouth, and preventing disease. On the flip side, the oral microbiome also plays an important role in the triggering, development, and progression of oral and systemic diseases. In recent years, disease diagnosis through the analysis of the human oral microbiome has been realized with the recent development of innovative detection technology and is overwhelmingly promising compared to the previous era. It has been found that patients with oral and systemic diseases have variations in their oral microbiome compared to normal subjects. This narrative review provides insight into the pathophysiological role that the oral microbiome plays in influencing oral and systemic diseases and furthers the knowledge related to the oral microbiome produced over the past 30 years. A wide range of updates were provided with the latest knowledge of the oral microbiome to help researchers and clinicians in both academic and clinical aspects. The microbial community information can be utilized in non-invasive diagnosis and can help to develop a new paradigm in precision medicine, which will benefit human health in the era of post-metagenomics.

Association of human T-cell leukemia virus type 1 with prevalent rheumatoid arthritis among atomic bomb survivors: A cross-sectional study

Previous studies have suggested that human T-cell leukemia virus type 1 (HTLV-1) might act as a pathogen in rheumatoid arthritis (RA), but epidemiological evidence of an association is scarce. We measured anti-HTLV-1 antibodies among Nagasaki atomic bomb survivors to determine whether HTLV-1 is related to RA and whether radiation exposure is associated with HTLV-1 and RA prevalence.This is a cross-sectional study among atomic bomb survivors who participated in biennial health examinations from 2006 to 2010. Serum levels of anti-HTLV-1 antibodies were measured using a chemiluminescent enzyme immunoassay and confirmed by Western blotting. Association between HTLV-1 and RA was analyzed by a logistic regression model.Of 2091 participants (women 61.5%; median age, 73 years), 215 (10.3%) had anti-HTLV-1 antibodies. HTLV-1 prevalence was higher among women (13.1% vs 5.8%; P < .001). Twenty-two participants (1.1%) were diagnosed with RA. HTLV-1 prevalence among RA participants was significantly higher than that among non-RA participants (27.3% vs 10.1%; P = .020). After adjustment for age, sex, and hepatitis C virus infection, HTLV-1 was significantly associated with prevalent RA (odds ratio, 2.89; 95% confidence interval, 1.06, 7.03). There was no association between radiation dose and either the prevalence of HTLV-1 or RA.This study, among a well-defined group of atomic bomb survivors, suggests that HTLV-1 is associated with 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.

Efficacy of doxycycline as a combination therapy in the treatment of rheumatoid arthritis: a randomized controlled clinical trial

Background

This single-center randomized open-label clinical trial evaluates the effectiveness of doxycycline as a combination therapy for active rheumatoid arthritis (RA) with methotrexate (MTX).

Materials and methods

One hundred and sixty RA patients were recruited who fulfilled the 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria. Subjects were randomly allocated in a 1:1 ratio into one of two treatment arms; one group was maintained on MTX alone and the other group on MTX together with doxycycline orally 200 mg daily. Follow-up clinical response, erythrocyte sedimentation rate (ESR), levels of C-reactive protein (CRP), and disease activity score 28 (DAS28-CRP) after 3 months were done.

Results

There was a significant difference regarding DAS28-CRP between the two groups (median (IQR) 4.26 (3.6–5) for those treated with MTX alone compared with 2.8 (2.37–3.5) for those treated with MTX together with doxycycline) (p = 0.005). A higher number of patients treated with doxycycline in combination with MTX achieved remission (40.5%) compared to patients who received MTX alone (13.5%). The levels of ESR and CRP were lower in patients treated with MTX and doxycycline and this was statistically significant (p = 0.005, p = 0.003 respectively).

Conclusion

Doxycycline as a cost-effective combination therapy with MTX can achieve higher rates of remission than MTX alone in RA patients without causing increase in the adverse events profile.

Trial registration

Clinical Trials.gov, NCT03194204. Registered on 21 June 2017

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.

Presence of salivary IgA anti-citrullinated protein antibodies associate with higher disease activity in patients with rheumatoid arthritis

Background

Circulating IgA anti-citrullinated protein antibodies (ACPA) associate with more active disease, but a previous study implied that salivary IgA ACPA is related to a less severe disease. Therefore, we aimed to characterize the IgA ACPA response in the saliva and serum in relation to clinical picture and risk factors among patients with rheumatoid arthritis (RA).

Methods

RA patients (n = 196) and healthy blood donors (n = 101), included in the cross-sectional study “Secretory ACPA in Rheumatoid Arthritis” (SARA), were analyzed for ACPA of IgA isotype, and for subclasses IgA1 and IgA2 ACPA in paired saliva and serum samples using modified enzyme-linked immunosorbent assays (ELISA) targeting reactivity to a cyclic citrullinated peptide (anti-CCP). Cutoff levels for positive tests were set at the 99th percentile for blood donors. Antibody levels were related to clinical characteristics, radiographic damage, smoking habits, and carriage of HLA-DRB1/shared epitope (SE).

Results

IgA ACPA in the saliva was found in 12% of RA patients, IgA1 occurred in 10%, and IgA2 in 9%. In serum, IgA ACPA was found in 45% of the patients, IgA1 in 44%, and IgA2 in 39%. Levels of IgA ACPA in the saliva correlated significantly with serum levels of IgA (r = 0.455). The presence of salivary IgA ACPA was associated with a higher erythrocyte sedimentation rate (ESR), 28-joint disease activity score, tender joint count, and patient global assessment at the time of sampling. None of the antibodies was associated with smoking, SE, or radiographic damage.

Conclusion

Salivary IgA ACPAs were detected in a subset of RA patients in association with higher disease activity. This suggests that mucosal ACPA responses in the oral cavity may contribute to disease-promoting processes in RA.

Microbial Influences of Mucosal Immunity in Rheumatoid Arthritis

PURPOSE OF REVIEW

This review will summarize recent data defining the relationship between rheumatoid arthritis (RA) and the microbiome at mucosal sites throughout the body. It will highlight what is known, what is speculated, and current knowledge gaps regarding the microbiome in RA.

RECENT FINDINGS

An extensive relationship between the microbiome and immune cell function can influence RA-related inflammation and T cell and B cell biology. Studies are beginning to characterize microbial changes in individuals who are at risk for RA, which is a critical element needed to understand the influence of the microbiome on RA pathogenesis. Expanding our understanding of the microbiome in RA beyond the bacteria at the gut and oral mucosae into the lung and urogenital surfaces, including viral and fungal components, and establishing the relationship across mucosal sites will be critical in future work. Importantly, approaches to manipulate the microbiome could lead to novel therapeutic and preventive strategies.

Dysbiosis in the oral microbiomes of anti-CCP positive individuals at risk of developing rheumatoid arthritis

OBJECTIVES

An increased prevalence of periodontitis and perturbation of the oral microbiome has been identified in patients with rheumatoid arthritis (RA). The periodontal pathogen Porphyromonas gingivalis may cause local citrullination of proteins, potentially triggering anti-citrullinated protein antibody production. However, it is not known if oral dysbiosis precedes the onset of clinical arthritis. This study comprehensively characterised the oral microbiome in anti-cyclic citrullinated peptide (anti-CCP) positive at-risk individuals without clinical synovitis (CCP+at risk).

METHODS

Subgingival plaque was collected from periodontally healthy and diseased sites in 48 CCP+at risk, 26 early RA and 32 asymptomatic healthy control (HC) individuals. DNA libraries were sequenced on the Illumina HiSeq 3000 platform. Taxonomic profile and functional capability of the subgingival microbiome were compared between groups.

RESULTS

At periodontally healthy sites, CCP+at risk individuals had significantly lower microbial richness compared with HC and early RA groups (p=0.004 and 0.021). Microbial community alterations were found at phylum, genus and species levels. A large proportion of the community differed significantly in membership (523 species; 35.6%) and structure (575 species; 39.1%) comparing CCP+at risk and HC groups. Certain core species, including P. gingivalis, had higher relative abundance in the CCP+at risk group. Seventeen clusters of orthologous gene functional units were significantly over-represented in the CCP+at risk group compared with HC (adjusted p value <0.05).

CONCLUSION

Anti-CCP positive at-risk individuals have dysbiotic subgingival microbiomes and increased abundance of P. gingivalis compared with controls. This supports the hypothesis that the oral microbiome and specifically P. gingivalis are important in RA initiation.

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.

Porphyromonas gingivalis and rheumatoid arthritis

PURPOSE OF REVIEW

To explore the pathogenic association between periodontal disease and rheumatoid arthritis focusing on the role of Porphyromonas gingivalis.

RECENT FINDINGS

In the last decades our knowledge about the pathogenesis of rheumatoid arthritis substantially changed. Several evidences demonstrated that the initial production of autoantibodies is not localized in the joint, rather in other immunological-active sites. A central role seems to be played by periodontal disease, in particular because of the ability of P. gingivalis to induce citrullination, the posttranslational modification leading to the production of anticitrullinated protein/peptide antibodies, the most sensitive and specific rheumatoid arthritis biomarker.

SUMMARY

The pathogenic role of P. gingivalis has been demonstrated in mouse models in which arthritis was either triggered or worsened in infected animals. P. gingivalis showed its detrimental role not only by inducing citrullination but also by means of other key mechanisms including induction of NETosis, osteoclastogenesis, and Th17 proinflammatory response leading to bone damage and systemic inflammation.

Targeting a cysteine protease from a pathobiont alleviates experimental arthritis

Background

Several lines of evidence suggest that the pathobiont Porphyromonas gingivalis is involved in the development and/or progression of auto-inflammatory diseases. This bacterium produces cysteine proteases, such as gingipain RgpA, endowed with the potential to induce significant bone loss in model systems and in patients.

Objective

We sought to gain further insight into the role of this pathobiont in rheumatoid arthritis (RA) and to identify novel therapeutic targets for auto-inflammatory diseases.

Methods

We profiled the antibody response to RgPA-specific domains in patient sera. We also tested the potential protective effects of RgpA domains in an experimental arthritis model.

Results

Pre-immunization of rats with purified recombinant RgpA domains alleviated arthritis in the joints of the rodents and reduced bone erosion. Using a functional genomics approach at both the mRNA and protein levels, we report that the pre-immunizations reduced arthritis severity by impacting a matrix metalloprotease characteristic of articular injury, a chemokine known to be involved in recruiting inflammatory cells, and three inflammatory cytokines. Finally, we identified an amino acid motif in the RgpA catalytic domain of P. gingivalis that shares sequence homology with type II collagen.

Conclusion

We conclude that pre-immunization against gingipain domains can reduce the severity of experimentally induced arthritis. We suggest that targeting gingipain domains by pre-immunization, or, possibly, by small-molecule inhibitors, could reduce the potential of P. gingivalis to translocate to remote tissues and instigate and/or exacerbate pathology in RA, but also in other chronic inflammatory diseases.

Periodontitis: a newly identified comorbidity in psoriasis and psoriatic arthritis

Introduction: Psoriasis is a chronic autoimmune skin disease with strong genetic background and environmental triggers. Patients with psoriasis and psoriatic arthritis are at greater risk of developing other chronic and potentially severe comorbidities, such as psoriatic arthritis, hyperlipidemia, type 2 diabetes mellitus, obesity, metabolic syndrome, cardiovascular diseases or depression. Recently, accumulating epidemiologic, genetic and pathogenetic evidence indicates that psoriasis is also associated with periodontitis, a chronic progressive inflammatory disease, which may result in tooth loss without early and adequate therapy.Areas covered: In this review article we summarize and discuss in detail the available epidemiologic, genetic, microbiological and immunological links between psoriasis and periodontitis.Expert opinion: Periodontitis, via the immunomodulatory effect of the oral microbiota, may play both a direct and indirect role in the development or exacerbation of psoriasis, and may influence the efficacy of antipsoriatic therapy. These new findings indicate a need for increased awareness, early recognition and focus on prevention of periodontitis for patients with psoriasis.

Molecular characterisation of the synovial fluid microbiome in rheumatoid arthritis patients and healthy control subjects

METHODS

The presence and identity of bacterial and fungal DNA in the synovial fluid of rheumatoid arthritis (RA) patients and healthy control subjects was investigated through amplification and sequencing of the bacterial 16S rRNA gene and fungal internal transcribed spacer region 2 respectively. Synovial fluid concentrations of the cytokines IL-6, IL-17A, IL22 and IL-23 were determined by ELISA.

RESULTS

Bacterial 16S rRNA genes were detected in 87.5% RA patients, and all healthy control subjects. At the phylum level, the microbiome was predominated by Proteobacteria (Control = 83.5%, RA = 79.3%) and Firmicutes (Control = 16.1%, RA = 20.3%), and to a much lesser extent, Actinobacteria (Control = 0.2%, RA = 0.3%) and Bacteroidetes (Control = 0.1%, RA = 0.1%). Fungal DNA was identified in 75% RA samples, and 88.8% healthy controls. At the phylum level, synovial fluid was predominated by members of the Basidiomycota (Control = 53.9%, RA = 46.9%) and Ascomycota (Control = 35.1%, RA = 50.8%) phyla. Statistical analysis revealed key taxa that were differentially present or abundant dependent on disease status.

CONCLUSIONS

This study reports the presence of a synovial fluid microbiome, and determines that this is modulated by disease status (RA) as are other classical microbiome niches.

A cross-sectional investigation into the association between Porphyromonas gingivalis and autoantibodies to citrullinated proteins in a German population

Background

Porphyromonas gingivalis (P.g) is unique among pathogens due to its ability to generate citrullinated proteins in an inflammatory milieu, potentially mediating the loss of immune tolerance, the production of anticitrullinated protein antibodies (ACPAs), and subsequently the development of rheumatoid arthritis (RA). Based on this hypothesis, we set out to investigate whether P.g is linked to ACPAs in a well-characterized German population.

Participants and methods

A total of 600 participants (292 women and 308 men with a mean age of 67 years) of the European Prospective Investigation into Cancer and Nutrition-Potsdam study were selected in 2013, and paired saliva and serum samples were collected. Salivary P.g DNA and serum anticyclic citrullinated peptide (anti-CCP2) levels were quantified by real-time polymerase chain reaction and anti-CCP2 enzyme-linked immunosorbent assay, respectively. In selected participants, additional ACPA fine-specificities were also analysed on a custom-made multiplex peptide array.

Results

Among participants with C-reactive protein greater than 3.0 mg/l, a one-unit increase in P.g DNA was associated with an almost twofold increase in anti-CCP2 levels. Moreover, participants with high P.g DNA had on average approximately 2.8-times higher anti-CCP2 levels when compared with participants with low P.g DNA, (Holm-adjusted p value = 0.01). Furthermore, citrullinated epitopes on α-enolase and vimentin were common ACPA reactivities among participants who also had high P.g DNA and elevated C-reactive protein.

Conclusions

Our study suggests that in specific subgroups of individuals with systemic inflammation, higher salivary P.g DNA is associated with elevated serum ACPA. These data support a role for P.g in the development of anticitrulline immunity.

Characteristics of Gut Microbiota in Patients With Rheumatoid Arthritis in Shanghai, China

Little is known regarding differences in the gut microbiomes of rheumatoid arthritis (RA) patients and healthy cohorts in China. This study aimed to identify differences in the fecal microbiomes of 66 Chinese patients with RA and 60 healthy Chinese controls. The V3-V4 variable regions of bacterial 16S rRNA genes were sequenced with the Illumina system to define the bacterial composition. The alpha-diversity index of the microbiome of the RA patients was significantly lower than that of the control group. The bacterial genera Bacteroides (p = 0.02202) and Escherichia-Shigella (p = 0.03137) were more abundant in RA patients. In contrast, Lactobacillus (p = 0.000014), Alloprevotella (p = 0.0000008615), Enterobacter (p = 0.000005759), and Odoribacter (p = 0.0000166) were less abundant in the RA group than in the control group. Spearman correlation analysis of blood physiological measures of RA showed that bacterial genera such as Dorea and Ruminococcus were positively correlated with RF-IgA and anti-CCP antibodies. Furthermore, Alloprevotella and Parabacteroides were positively correlated with the erythrocyte sedimentation rate, and Prevotella-2 and Alloprevotella were positively correlated with C-reactive protein, both biomarkers of inflammation. These findings suggest that the gut microbiota may contribute to RA development via interactions with the host immune system.

Gums and joints: is there a connection? Part two: the biological link

Rheumatoid arthritis (RA) and periodontitis (PD) are inflammatory diseases characterised by an exacerbated immune-inflammatory reaction that leads to the destruction of bone and other connective tissues that share numerous similarities. Although a significant and independent association between these two conditions has been described, the pathophysiological processes that may explain this relationship remain unknown and multiple theories have been proposed. This review presents the most important theories currently proposed to explain the biological link between RA and PD.

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.

Association between anti-Porphyromonas gingivalis antibody, anti-citrullinated protein antibodies, and rheumatoid arthritis : A meta-analysis

OBJECTIVE

The aim of this study was to determine the relationship between anti-Porphyromonas gingivalis (anti-P. gingivalis) antibody levels and rheumatoid arthritis (RA) and its correlation with anti-citrullinated protein antibodies (ACPA).

METHODS

We performed a meta-analysis of studies comparing (a) anti-P. gingivalis antibody levels in RA patients and healthy controls and (b) the correlation coefficients between the anti-P. gingivalis antibody levels and ACPA in RA patients.

RESULTS

The study included 14 articles with 3829 RA patients and 1239 controls. Our meta-analysis showed that anti-P. gingivalis antibody levels were significantly higher in the RA group than in the control group (standardized mean difference [SMD] = 0.630, 95% CI = 0.272-0.989, p = 0.001). Subgroup analysis revealed that RA patients had significantly elevated anti-P. gingivalis antibody levels compared with healthy controls, but not compared with the non-RA control group and also not between different sample sizes. Anti-P. gingivalis antibody levels were significantly higher in the RA group than in the control group in the age-/sex-matched population, but not in the unmatched population. Anti-P. gingivalis antibody levels were significantly higher in the ACPA-positive group than in the ACPA-negative group (SMD = 0.322, 95% CI = 0.164-0.480, p = 6.4 × 10^-5). Meta-analysis of the correlation coefficients showed a significant positive correlation between anti-P. gingivalis antibody levels and ACPA (correlation coefficient = 0.147, 95% CI = 0.033-0.258, p = 0.012).

CONCLUSION

Our meta-analysis demonstrated that anti-P. gingivalis antibody levels were significantly higher in patients with RA and they were positively correlated with ACPA.

Role of good oral hygiene on clinical evolution of rheumatoid arthritis: a randomized study nested in the ESPOIR cohort

Objective

There is a relationship between RA and periodontal disease. We aimed to investigate if a good oral hygiene could improve activity of RA.

Methods

The patients with RA according to ACR/EULAR 2010 criteria and included in the French early arthritis ESPOIR cohort were included in a randomized nested study into: (i) intervention group: general recommendations of good oral hygiene including teeth brushing, daily antiseptic mouthwash and twice a year scaling; and (ii) control group: no intervention. The primary end point was the delta DAS28-ESR.

Results

Four hundred and seventy-two patients were randomized (238 in intervention and 234 in control). 92/238 from the intervention group accepted the procedure and 81 had a first visit to the dentist. 56% of patients had periodontal disease at baseline. Duration of RA was 9.0±0.7 years. Baseline DAS28-ESR was 2.7±1.3. After a median duration of 24 months, delta DAS28-ESR was −0.17±1.29 and −0.09±1.28 in intervention and control groups, respectively (mean difference (complier average causal effect): −0.37 (95% CI −1.12, 0.37), P = 0.33). In the intervention group, there was a significant decrease of the bacteria involved in the red complex: Porphyromonas gingivalis (P = 0.002), Tannerella forsythia (P = 0.002) and Treponema denticola (P = 0.019). The patients with baseline periodontal disease and those who became negative for one red complex bacterium had a slightly more important decrease of DAS28-ESR.

Conclusion

Oral hygiene instruction together with regular scaling and polishing of the teeth significantly decreased the load of periodontal pathogens but did not decrease RA activity. This intervention should be tested in patients with earlier RA and more active disease.

Trial registration

ClinicalTrials.gov, http://clinicaltrials.gov, NCT01831648.

A Prospective Study of the Development of Inflammatory Arthritis in the Family Members of Indigenous North American People With Rheumatoid Arthritis

OBJECTIVE

To determine the incidence of inflammatory arthritis and autoantibody prevalence in Indigenous North American people.

METHODS

Unaffected relatives of Indigenous North Americans with rheumatoid arthritis (RA) from central Canada and Alaska were systematically monitored from 2005 to 2017. Rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPAs) were tested at every visit, and a subset was tested for ACPA fine specificity using a custom multiplex assay. Multistate models based on all available study visits were developed to determine the likelihood of transitioning between autoantibody states, or to inflammatory arthritis.

RESULTS

Eighteen of 374 relatives (4.8%) developed inflammatory arthritis during follow-up (after a mean ± SD of 4.7 ± 2.4 years), yielding a transition rate of 9.2 cases/1,000 person-years. Thirty percent of those who developed inflammatory arthritis were seronegative at baseline, but all were seropositive at inflammatory arthritis onset. Although 30% of ACPA/RF double-seropositive individuals developed inflammatory arthritis (after 3.2 ± 2.2 years), the majority of these individuals did not develop inflammatory arthritis. Multistate modeling indicated a 71% and 68% likelihood of ACPA and RF seropositive states, respectively, reverting to a seronegative state after 5 years, and a 39% likelihood of an ACPA/RF double-seropositive state becoming seronegative. Fine specificity testing demonstrated an expansion of the ACPA repertoire prior to the development of inflammatory arthritis.

CONCLUSION

Despite a high incidence of inflammatory arthritis in this cohort of at-risk relatives of Indigenous North Americans with RA, a large proportion of autoantibody-positive individuals do not develop inflammatory arthritis and revert back to an autoantibody-negative state.

Early Rheumatoid Arthritis Presentation, Treatment, and Outcomes in Aboriginal Patients in Canada: A Canadian Early Arthritis Cohort Study Analysis

OBJECTIVE

Health inequities exist in chronic diseases for Aboriginal people. This study compared early rheumatoid arthritis (RA) presentation, treatment, and outcomes between Aboriginal and white patients in a large Canadian cohort study.

METHODS

Longitudinal data from the Canadian Early Arthritis Cohort, a prospective multicenter early RA study, were analyzed for participants who self-identified as Aboriginal or white ethnicity. Disease characteristics at presentation, prognostic factors, frequency of remission, and disease-modifying therapy strategies were contrasted between population groups. Linear mixed models were used to estimate rates of change for disease activity measures over a 5-year period.

RESULTS

At baseline, 2,173 participants (100 Aboriginal and 2,073 white) had similar mean ± SD symptom duration (179 ± 91 days), 28-joint Disease Activity Scores (DAS28; 4.87 ± 1.48), and Health Assessment Questionnaire (0.88 ± 0.68) scores. Factors associated with poor prognosis were more frequently present in Aboriginal participants, but disease-modifying therapy selection and frequency of therapy escalation was similar between the 2 groups. DAS28 remission was achieved less frequently in Aboriginal than in white participants (adjusted odds ratio 0.39 [95% confidence interval 0.25-0.62]). Results were primarily driven by slower improvement in swollen joint counts and nonsignificant improvement in patient global scores in Aboriginal participants. Pain levels remained higher in Aboriginal patients.

CONCLUSION

Aboriginal early RA patients experienced worse disease outcomes than their white counterparts. This may reflect unmeasured biologic differences and/or disparities in prognostic factors informed by inequities in determinants of health. The appropriateness of current treatment strategies applied in different contexts should be considered.

Mucosa Biology and the Development of Rheumatoid Arthritis: Potential for Prevention by Targeting Mucosal Processes

As the goal in rheumatoid arthritis (RA) management shifts toward the prevention of joint disease, it is important to consider the role of mucosal sites in the pathogenesis of RA because they may be potential targets for preventive interventions. Multiple mucosal sites demonstrate immune dysregulation and inflammation in individuals with classifiable RA as well as, importantly, in individuals with systemic autoimmunity related to RA. The lung, gingival, and gastrointestinal mucosae are most strongly implicated in RA pathogenesis and may be sites where autoimmunity in RA initially develops. Targeting the exact site where the initial immune dysregulation in RA occurs is an appealing approach to prevention because it could avoid unwanted side effects of systemic therapies. However, several challenges must be addressed before mucosa-targeted interventions are a readily available option for RA prevention. Studies are needed to determine whether all RA-related immune dysregulation at mucosal sites will progress to joint disease and whether one or multiple mucosal sites demonstrate dysregulation prior to the development of classifiable RA. These areas of future research are likely to provide crucial pieces in the understanding of RA pathogenesis and ultimately RA prevention.

Occurrence of anti-CCP2 and RF isotypes and their relation to age and disease severity among Sudanese patients with rheumatoid arthritis

OBJECTIVE

Anti-cyclic citrullinated peptide 2 antibodies (anti-CCP2) and rheumatoid factor (RF) in rheumatoid arthritis (RA) has been extensively assessed in industrialized countries. We investigated the diagnostic and prognostic impact of anti-CCP2 and RF isotypes in a Sudanese cross-sectional RA cohort.

METHODS

Consecutive RA patients (n = 281) diagnosed according to the 1987 ACR criteria were included 2008-2010. Anti-CCP2 and RF isotypes (IgA, IgM, and IgG) were measured by enzyme immunoassay in 262 patients, with reference intervals aligned to the same diagnostic specificity as for anti-CCP2 (97.6%) using national controls.

RESULTS

IgA RF was the predominant RA-associated autoantibody (56%), followed by IgM RF and anti-CCP2 (both 52%) and IgG RF (49%). In receiver operator characteristic analysis, IgA RF also showed the largest area under the curve. Patients with IgG RF were younger and had 8 years lower median age of disease onset compared to antibody negative patients (p < 0.0001). IgG RF was the only marker associated with a high number of involved joints (p = 0.028), and together with anti-CCP2 were the strongest markers for finger deformities (p = 0.016 and p = 0.012), respectively. No statistical differences were found for disease duration, ESR and Hb levels, and occurrence of erosions/osteopenia for any of the investigated autoantibodies.

CONCLUSION

Whereas IgA RF showed the best diagnostic performance, IgG RF associated with low age of RA onset, high number of involved joints, and finger deformities. These findings indicate that RA-associated antibodies other than conventional IgM RF and anti-CCP2 might be informative in non-Caucasian RA populations.