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ObjectiveTo evaluate whether the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) is a responsive instrument in psoriatic arthritis (PsA) and whether it differentiates between axial and peripheral disease activity in PsA.MethodsIndividuals with PsA initiating therapy in a longitudinal cohort study based in the United States were included. Axial PsA (axPsA), most often also associated with peripheral disease, was defined as fulfillment of the Assessment of Spondyloarthritis international Society axial spondyloarthritis classification criteria or presence of axial disease imaging features. Baseline BASDAI, individual BASDAI items, patient global assessment, patient pain, and Routine Assessment of Patient Index Data 3, and score changes following therapy initiation were descriptively reported. Standardized response means (SRMs) were calculated as the mean change divided by the SD of the change.ResultsThe mean (SD) baseline BASDAI score at the time of therapy initiation was 5.0 (2.2) among those with axPsA (n = 40) and 4.8 (2.0) among those with peripheral-only disease (n = 79). There was no significant difference in patient-reported outcome scores between the groups. The mean change for BASDAI was similar among axial vs peripheral disease (−0.75 vs −0.83). SRMs were similar across axial vs peripheral disease for BASDAI (−0.37 vs −0.44) and the individual BASDAI items.ConclusionBASDAI has reasonable responsiveness in PsA but does not differentiate between axPsA and peripheral PsA. (ClinicalTrials.gov: NCT03378336)

ObjectivePsoriatic disease remains underdiagnosed and undertreated. We developed and validated a suite of novel, sensor-based smartphone assessments (Psorcast app) that can be self-administered to measure cutaneous and musculoskeletal signs and symptoms of psoriatic disease.MethodsParticipants with psoriasis (PsO) or psoriatic arthritis (PsA) and healthy controls were recruited between June 5, 2019, and November 10, 2021, at 2 academic medical centers. Concordance and accuracy of digital measures and image-based machine learning models were compared to their analogous clinical measures from trained rheumatologists and dermatologists.ResultsOf 104 study participants, 51 (49%) were female and 53 (51%) were male, with a mean age of 42.3 years (SD 12.6). Seventy-nine (76%) participants had PsA, 16 (15.4%) had PsO, and 9 (8.7%) were healthy controls. Digital patient assessment of percent body surface area (BSA) affected with PsO demonstrated very strong concordance (Lin concordance correlation coefficient [CCC] 0.94 [95% CI 0.91-0.96]) with physician-assessed BSA. The in-clinic and remote target plaque physician global assessments showed fair-to-moderate concordance (CCCerythema0.72 [0.59-0.85]; CCCinduration0.72 [0.62-0.82]; CCCscaling0.60 [0.48-0.72]). Machine learning models of hand photos taken by patients accurately identified clinically diagnosed nail PsO with an accuracy of 0.76. The Digital Jar Open assessment categorized physician-assessed upper extremity involvement, considering joint tenderness or enthesitis (AUROC 0.68 [0.47-0.85]).ConclusionThe Psorcast digital assessments achieved significant clinical validity, although they require further validation in larger cohorts before use in evidence-based medicine or clinical trial settings. The smartphone software and analysis pipelines from the Psorcast suite are open source and freely available.

To determine the responsiveness to therapy and minimum clinically important improvement (MCII) for patient‐reported outcome measures in psoriatic arthritis (PsA) and to examine the impact of baseline disease activity on the ability to demonstrate change. A longitudinal cohort study was performed within the PsA Research Consortium. Patients completed several patient‐reported outcomes, including the Routine Assessment of Patient Index Data, the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), the Psoriatic Arthritis Impact of Disease 12‐item (PsAID12) questionnaire, and others. The mean change in the scores between visits and standardized response means (SRMs) were calculated. The MCII was calculated as the mean change in score among patients who reported minimal improvement. SRMs and MCIIs were compared among subgroups with moderate to highly active PsA and those with lower disease activity. Among 171 patients, 266 therapy courses were included. The mean ± SD age was 51 ± 13.8 years, 53% were female, and the mean swollen and tender joint counts were 3 and 6, respectively, at baseline. SRMs and MCII for all measures were small to moderate, although greater among those with higher baseline disease activity. BASDAI had the best SRM overall and for less active PsA, and the clinical Disease Activity of PsA (cDAPSA) and PsAID12 were best for those with higher disease activity. SRMs and MCII were relatively small in this real‐world population, particularly among those with lower disease activity at baseline. BASDAI, cDAPSA, and PsAID12 had good sensitivity to change, but selection for use in trials should consider the baseline disease activity of patients to be enrolled.

Backgroud Psoriatic arthritis (PsA) is a chronic, inflammatory arthritis that, when left untreated, can lead to erosions, deformities and decrease in quality of life. PsA is known to be associated with multiple comorbidities, including cardiovascular, metabolic and mental health syndromes, all of which can increase its overall morbidity and mortality.Objective To characterize a cohort of patients with PsA and understand the impact of depression on PsA outcome measures.Methods 527 consecutive patients with PsA were enrolled in an observational, longitudinal registry that followed them prospectively at standard of care visits. Demographics, medical history, medication use, and clinical exam were all recorded.Results Depression was reported in 22.8% of the population, anxiety in 18%, and attention deficit hyperactivity disorder in 4%. Depression was more common in female participants (P < .001). At baseline, individuals with PsA and concomitant depression had similar tender and swollen joint counts and RAPID3 compared to those without depression, and had lower body surface area affected by psoriasis (P = .04). At year one, all patients had improvement in clinical outcomes. However, patients with depression had a significantly higher tender joint count compared to those without depression (P = .001), despite similar swollen joint count and body surface area.Conclusion In patients with depression, there is a discrepancy between improvement in physician assessed measures and patient reported outcomes. These observations underscore the importance of addressing depression and psychological distress as part of PsA treatment outcomes and points towards the need to address residual pain through co-adjuvant approaches.

The Psoriasis and Psoriatic Arthritis Clinics Multicenter Advancement Network (PPACMAN) is a nonprofit organization whose mission is to optimize the clinical care of patients with psoriatic disease through multidisciplinary collaboration models. The PPACMAN 2021 Annual Meeting was held virtually on December 11, 2021. In all, 50 stakeholders participated in the meeting including dermatologists, rheumatologists, cardiologists, clinical researchers, patient advocacy representatives, and industry representatives. During the opening session of the meeting, presenters provided an update of several research projects dedicated to predicting and preventing psoriatic arthritis (PsA) such as the Psorcast, PAMPA, HIPPOCRATES, and the ELLIPSS studies. The second session centered around novel approaches to deliver multidisciplinary care in psoriatic disease. PPACMAN leadership introduced its wellness program and invited speakers to discuss new advances in cardiovascular disease, sleep disturbance, mental health problems, and dietary interventions in psoriatic disease. The final session of the meeting focused on how to improve patient engagement in their disease and care.

ObjectiveTo evaluate secukinumab (SEC) 300 mg and 150 mg vs placebo in a United States–only population of biologic-nai¨ve patients with psoriatic arthritis (PsA).MethodsCHOICE was a double-blind, randomized controlled trial conducted in the US. Biologic-nai¨ve patients with PsA and psoriasis (PsO) were randomized 2:2:1 to SEC 300 mg (n = 103), SEC 150 mg (n = 103), or placebo (n = 52). The primary objective was to show superiority of SEC 300 mg vs placebo in American College of Rheumatology 20% (ACR20) response at week 16. Additional objectives included the effect of SEC on dactylitis, enthesitis, PsO, and safety.ResultsACR20 response rates at week 16 were higher with SEC 300 mg than with placebo (51.5% vs 23.1%; odds ratio 3.51 [95% CI 1.65-7.45]; P= 0.001). SEC 300 mg also led to greater ACR50/70 responses and improvements in other variables vs placebo. Responses were generally sustained over time. Patients with inadequate response to SEC 150 mg at weeks 16, 28, or 40 who received dose escalation to 300 mg experienced improved clinical response after uptitration. The most common adverse events were upper respiratory tract infections and diarrhea. No inflammatory bowel disease was reported or new safety signals observed.ConclusionSEC 300 mg led to rapid and significant improvements over placebo in symptoms of PsA in this heavier population of US-only, biologic-nai¨ve patients. Findings were consistent with previous studies and suggest that SEC 300 mg is a safe and efficacious first-line biologic treatment for patients with PsA. [ClinicalTrials.gov: NCT02798211]

At the 2021 Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA)-Collaborative Research Network (CRN) annual meeting, the GRAPPA-CRN group presented a number of project updates, including a pilot investigator-initiated study to evaluate liquid and tissue biomarkers associated with axial involvement in psoriatic arthritis (PsA). The GRAPPA-CRN session updated progress made with 3 parallel international research initiatives based on 3 previously defined unmet needs in PsA. The Health Initiatives in Psoriasis and PsOriatic arthritis ConsoRTium European States (HIPPOCRATES) is a European research consortium formed to address unmet clinical needs in PsA. The Preventing Arthritis in a multicenter Psoriasis At-Risk Population (PAMPA) is a US-based organization that has defined consensus terminology for preclinical phases of PsA and is interested in the transition process from psoriasis to PsA. An overview of the Accelerating Medicines Partnership Autoimmune and Immune-Mediated Diseases (AMP AIM) program 2.0, a consortium including GRAPPA-CRN members that addressed these 3 unmet needs in PsA, was also presented.

The second basic science session at the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) annual meeting focused on 2 recent publications that have increased our understanding of the pathogenesis of psoriatic arthritis (PsA). Data from the first publication, presented by Prof. Erik Lubberts, showed that interleukin (IL)-17A is produced by CD4+ and not CD8+ T cells in PsA synovial fluid following T cell receptor activation. These findings contrast with previously published data, which had suggested that CD8+ T cells are a prominent source of IL-17A. In further experiments, they showed that when CD8+ T cells were stimulated with paramethoxyamphetamine/ionomycin, relatively high levels of IL-17A were detected. Prof. Jose Scher presented work on the role of the microbiome in PsA and more specifically, on pharmacomicrobiomics. He demonstrated the baseline collection of genomes and genes from the microbiota community (the metagenome) can be used as predictor for future treatment response in early rheumatoid arthritis and also likely in PsA.

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of mature T-cell neoplasms characterized by the accumulation of clonal malignant CD4+ T cells in the skin. The most common variant of CTCL, mycosis fungoides (MF ), is confined to the skin in early stages but can be accompanied by extracutaneous dissemination of malignant T cells to the blood and lymph nodes in advanced stages of disease. Sézary syndrome (SS), a leukemic form of disease, is characterized by significant blood involvement. Little is known about the transcriptional and genomic relationship between skin- and blood-residing malignant T cells in CTCL. To identify and interrogate malignant clones in matched skin and blood from patients with leukemic MF and SS, we combine T-cell receptor clonotyping with quantification of gene expression and cell surface markers at the single cell level. Our data reveal clonal evolution at a transcriptional and genetic level within the malignant populations of individual patients. We highlight highly consistent transcriptional signatures delineating skin- and blood-derived malignant T cells. Analysis of these 2 populations suggests that environmental cues, along with genetic aberrations, contribute to transcriptional profiles of malignant T cells. Our findings indicate that the skin microenvironment in CTCL promotes a transcriptional response supporting rapid malignant expansion, as opposed to the quiescent state observed in the blood, potentially influencing efficacy of therapies. These results provide insight into tissue-specific characteristics of cancerous cells and underscore the need to address the patients’ individual malignant profiles at the time of therapy to eliminate all subclones.

The concept of psoriatic arthritis (PsA) prevention is gaining increased interest owing to the physical limitation, poor quality of life and low remission rates that are achieved with current therapies for PsA. The psoriasis-to-PsA transition offers a unique opportunity to identify individuals at increased risk of developing PsA and to implement preventive strategies. However, identifying individuals at increased risk of developing PsA is challenging as there is no consensus on how this population should be defined. This Consensus Statement puts forward recommended terminology from the Psoriasis and Psoriatic Arthritis Clinics Multicenter Advancement Network (PPACMAN) for defining specific subgroups of individuals during the preclinical and early clinical phases of PsA to be used in research studies. Following a three-round Delphi process, consensus was reached for three terms and definitions: ‘increased risk for PsA’, ‘psoriasis with asymptomatic synovio-entheseal imaging abnormalities’ and ‘psoriasis with musculoskeletal symptoms not explained by other diagnosis’. These terms and their definitions will enable improved identification and standardization of study populations in clinical research. In the future, as increasing evidence emerges regarding the molecular and clinical features of the psoriasis-to-PsA continuum, these terms and definitions will be further refined and updated.

Psoriatic arthritis (PsA) is a systemic chronic inflammatory disease that develops in up to 30% of patients with psoriasis. Mixed data variably support the potential ability to “prevent” and/or delay PsA through use of systemic therapies in psoriasis patients. Though intriguing, almost all of these studies are retrospective in nature, and hold substantial limitations and potential biases that challenge the ability to meaningfully interpretation their results. Thus, the authors believe prospective observational and interventional studies are crucial to understanding our ability to truly modify the transition from psoriasis to psoriatic arthritis and delay or prevent PsA onset.

Enormous progress has been made in the field of rheumatology in the past several decades, historically led by publicly funded academic innovators but in more recent times with much greater involvement of the pharmaceutical industry. This shift in resources has created a complex new model for reinvestment in the medical community in which the vast majority of private funds are redirected towards influencing the prescription behaviour of practitioners through ‘key opinion leaders’, with the main purpose of enhancing and perpetuating profit rather than innovation and critical thinking, and often at the expense of partnerships with scientists (that is, basic and translational researchers) and academic collaborations. This new episteme brings multiple opportunities to rethink approaches to sustaining long-term critical research in the field, ultimately maximizing the return on investment: scientific knowledge for the benefit of patients and society. Central to such strategies should be the rebalancing of academia–industry partnerships towards academic research and the involvement of ‘innovation and knowledge leaders’, rather than mostly key opinion leaders.

The coronavirus disease 2019 (COVID-19; caused by SARS-CoV-2) pandemic has affected the healthcare system on a global scale, and we utilized the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) 2020 annual meeting to examine how COVID-19 might affect patients with psoriatic disease (PsD) and the clinicians who care for them. Pressing issues and concerns identified included whether having psoriasis increased the risk of acquiring COVID-19, vaccine safety, and the acceptability of telehealth. The general message from rheumatologists, dermatologists, infectious disease specialists, and patient research partners was that data did not suggest that having PsD or its treatment significantly increased risk of infection or more severe disease course, and that the telehealth experience was a success overall.

At the 2020 Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA)-Collaborative Research Network (CRN) annual meeting, the GRAPPA-CRN group presented a pilot investigator-initiated study protocol to test electronic case report forms (eCRFs) and proposed Standardized Operating Procedures (SOPs) to evaluate biomarkers of psoriatic arthritis (PsA) associated with axial disease. The progress on 3 studies was also presented: BioDAM PsA (Biomarkers as Predictors of structural DAMage in PsA; to validate soluble biomarkers as predictors of structural damage in PsA), PreventPsA (examining the development of PsA and risk factors among patients with psoriasis and no arthritis), and PredictORPsA (Predicting Treatment respOnse in patients with eaRly PsA; in collaboration with Pfizer using samples from the Oral Psoriatic Arthritis TriaL [OPAL], to identify biomarkers of treatment response). GRAPPA-CRN funding partnerships and applications are also underway with both the Innovative Medicines Initiative (IMI) in Europe and Accelerating Medicines Partnerships (AMP) 2.0 in the USA, and the progress of these applications and associated objectives were presented.

Supplemental Digital Content is available in the text.

In the past three decades, extraordinary advances have been made in the understanding of the pathogenesis of, and treatment options for, inflammatory arthritides, including rheumatoid arthritis and spondyloarthritis. The use of methotrexate and subsequently biologic therapies (such as TNF inhibitors, among others) and oral small molecules have substantially improved clinical outcomes for many patients with inflammatory arthritis; for others, however, these agents do not substantially improve their symptoms. The emerging field of pharmacomicrobiomics, which investigates the effect of variations within the human gut microbiome on drugs, has already provided important insights into these therapeutics. Pharmacomicrobiomic studies have demonstrated that human gut microorganisms and their enzymatic products can affect the bioavailability, clinical efficacy and toxicity of a wide array of drugs through direct and indirect mechanisms. This discipline promises to facilitate the advent of microbiome-based precision medicine approaches in inflammatory arthritis, including strategies for predicting response to treatment and for modulating the microbiome to improve response to therapy or reduce drug toxicity.

The Psoriasis and Psoriatic Arthritis Clinics Multicenter Advancement Network (PPACMAN) was established to optimize the clinical care of patients with psoriatic disease through multidisciplinary collaboration, education, and innovative research. This article is a report of the 2018 PPACMAN Annual Meeting held in New York City, on December 8, 2018. At this meeting, attendees discussed the benefits and challenges of combined dermatology/rheumatology clinics and PPACMAN ongoing project updates. In addition, collaborators participated in breakout sessions and plenary voting dedicated to achieving consensus on terminology for preclinical psoriatic arthritis studies, one of PPACMAN’s main areas of interest. The data obtained from this voting exercise were used to draft a formal Delphi survey that is currently underway.

Dual neutralisation of interleukin 17A (IL17A) and interleukin 17F (IL17F) is a potential novel therapeutic approach in psoriatic arthritis. We assessed bimekizumab, a monoclonal antibody that selectively neutralises IL17A and IL17F, in patients with active psoriatic arthritis.

ObjectiveTo examine the construct validity of Routine Assessment of Patient Index Data 3 (RAPID3) and Psoriatic Arthritis Impact of Disease (PsAID) in patients with psoriatic arthritis (PsA). In examining construct validity, we also addressed scores among subgroups with severe psoriasis, poly articular disease, enthesitis, and dactylitis, and evaluated influences of sociodemographic factors and comorbidities (contextual factors) on these patient-reported outcomes (PRO).MethodsPatients with PsA were enrolled in the Psoriatic Arthritis Research Consortium (PARC) between 2014 and 2016. PARC is a longitudinal observational cohort study conducted at 4 US institutions. In this cross-sectional study, construct validity was assessed by examining Spearman correlation coefficients for RAPID3 and PsAID with physician-reported disease activity measures and other PRO [e.g., Medical Outcomes Study Short Form-12 physical component summary/mental component summary (SF-12 PCS/MCS), Functional Assessment of Chronic Illness Therapy–Fatigue scale (FACIT-F)]. Contextual factors and disease subgroups were assessed in multivariable linear regression models with RAPID3 or PsAID12 as outcomes of interest and the hypothesized contextual factors as covariates.ResultsAmong 401 patients enrolled in PARC, 347 completed RAPID3 or PsAID12. Of these, most were white females with a mean age of 51.7 years (SD 14.02). RAPID3 and PsAID were highly correlated (r = 0.90). These measures were also correlated with the SF-12 PCS (r = −0.67) and FACIT-F (r = −0.77). Important contextual factors and disease subgroups included enthesitis, joint counts, education, insurance type, and depression.ConclusionRAPID3 and PsAID12 have excellent construct validity in PsA and are strongly correlated despite differing items. Contextual factors (i.e., the presence of depression and obesity) should be considered when interpreting raw scores of the RAPID3 and PsAID12.

Supplemental Digital Content is available in the text.

Objective: To develop an evidence-based guideline for the pharmacologic and nonpharmacologic treatment of psoriatic arthritis (PsA), as a collaboration between the American College of Rheumatology (ACR) and the National Psoriasis Foundation (NPF).Methods: We identified critical outcomes in PsA and clinically relevant PICO (population/intervention/comparator/outcomes) questions. A Literature Review Team performed a systematic literature review to summarize evidence supporting the benefits and harms of available pharmacologic and nonpharmacologic therapies for PsA. GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology was used to rate the quality of the evidence. A voting panel, including rheumatologists, dermatologists, other health professionals, and patients, achieved consensus on the direction and the strength of the recommendations.Results: The guideline covers the management of active PsA in patients who are treatment-naive and those who continue to have active PsA despite treatment, and addresses the use of oral small molecules, tumor necrosis factor inhibitors, interleukin-12/23 inhibitors (IL-12/23i), IL-17 inhibitors, CTLA4-Ig (abatacept), and a JAK inhibitor (tofacitinib). We also developed recommendations for psoriatic spondylitis, predominant enthesitis, and treatment in the presence of concomitant inflammatory bowel disease, diabetes, or serious infections. We formulated recommendations for a treat-to-target strategy, vaccinations, and nonpharmacologic therapies. Six percent of the recommendations were strong and 94% conditional, indicating the importance of active discussion between the health care provider and the patient to choose the optimal treatment.Conclusion: The 2018 ACR/NPF PsA guideline serves as a tool for health care providers and patients in the selection of appropriate therapy in common clinical scenarios. Best treatment decisions consider each individual patient situation. The guideline is not meant to be proscriptive and should not be used to limit treatment options for patients with PsA.

To develop an evidence‐based guideline for the pharmacologic and nonpharmacologic treatment of psoriatic arthritis (PsA), as a collaboration between the American College of Rheumatology (ACR) and the National Psoriasis Foundation (NPF). We identified critical outcomes in PsA and clinically relevant PICO (population/intervention/comparator/outcomes) questions. A Literature Review Team performed a systematic literature review to summarize evidence supporting the benefits and harms of available pharmacologic and nonpharmacologic therapies for PsA. GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology was used to rate the quality of the evidence. A voting panel, including rheumatologists, dermatologists, other health professionals, and patients, achieved consensus on the direction and the strength of the recommendations. The guideline covers the management of active PsA in patients who are treatment‐naive and those who continue to have active PsA despite treatment, and addresses the use of oral small molecules, tumor necrosis factor inhibitors, interleukin‐12/23 inhibitors (IL‐12/23i), IL‐17 inhibitors, CTLA4‐Ig (abatacept), and a JAK inhibitor (tofacitinib). We also developed recommendations for psoriatic spondylitis, predominant enthesitis, and treatment in the presence of concomitant inflammatory bowel disease, diabetes, or serious infections. We formulated recommendations for a treat‐to‐target strategy, vaccinations, and nonpharmacologic therapies. Six percent of the recommendations were strong and 94% conditional, indicating the importance of active discussion between the health care provider and the patient to choose the optimal treatment. The 2018 ACR/NPF PsA guideline serves as a tool for health care providers and patients in the selection of appropriate therapy in common clinical scenarios. Best treatment decisions consider each individual patient situation. The guideline is not meant to be proscriptive and should not be used to limit treatment options for patients with PsA.

The microbiome is a known and established immunomodulator of many inflammatory disorders, including psoriasis and psoriatic arthritis. Microbes co-evolved with their human hosts and provide them with nutritional, metabolic, and immunologic support. An accumulating body of evidence has revealed that psoriatic diseases are characterized by a state of intestinal dysbiosis, which has been linked to a decrease in beneficial commensals and fatty acids. This has been shown in both animal models and human samples, and multiple studies have addressed the physiological and potentially pathogenic role of intestinal and cutaneous microbes in human health and disease. In this review, we discuss state-of-the-art literature in the field of the microbiome in psoriatic diseases that was presented during the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) 2017 annual meeting, with a special emphasis on synovio-entheseal inflammation. A better understanding of these microbe-host interactions can lead to novel diagnostic and therapeutic targets.

At the 2021 Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) annual meeting, a summary of the research conducted by the recipients of the 2020 GRAPPA Research Awards was presented by the awardees. The summary of the 4 presentations is provided here.

The role of the gut microbiome in animal models of inflammatory and autoimmune disease is now well established. The human gut microbiome is currently being studied as a potential modulator of the immune response in rheumatic disorders. However, the vastness and complexity of this host–microorganism interaction is likely to go well beyond taxonomic, correlative observations. In fact, most advances in the field relate to the functional and metabolic capabilities of these microorganisms and their influence on mucosal immunity and systemic inflammation. An intricate relationship between the microbiome and the diet of the host is now fully recognized, with the microbiota having an important role in the degradation of polysaccharides into active metabolites. This Review summarizes the current knowledge on the metabolic role of the microbiota in health and rheumatic disease, including the advances in pharmacomicrobiomics and its potential use in diagnostics, therapeutics and personalized medicine.

Since the early 1900s, the role of periodontal disease in the pathogenesis of rheumatoid arthritis has been a matter of intense research. The last decade has witnessed many advances supporting a link between periodontitis, the presence of specific bacterial species (i.e. Porphyromonas gingivalis) and their effects in immune response. This review will examine available evidence on the individuals.

Despite the progress toward understanding the molecular pathogenesis of rheumatoid arthritis (RA), its cause remains elusive. Genes are important but rather insufficient to explain the majority of RA cases. This review describes the novel data supporting the microbiome and its interactions with the human host as potential en(‘in’)vironmental factors in RA pathogenesis.