Microbial Infection and Rheumatoid Arthritis

The peculiar features, diversity and impact of citrulline-reactive autoantibodies

Since entering the stage 25 years ago as a highly specific serological biomarker for rheumatoid arthritis, anti-citrullinated protein antibodies (ACPAs) have been a topic of extensive research. This hallmark B cell response arises years before disease onset, displays interpatient autoantigen variability, and is associated with poor clinical outcomes. Technological and scientific advances have revealed broad clonal diversity and intriguing features including high levels of somatic hypermutation, variable-domain N-linked glycosylation, hapten-like peptide interactions, and clone-specific multireactivity to citrullinated, carbamylated and acetylated epitopes. ACPAs have been found in different isotypes and subclasses, in both circulation and tissue, and are secreted by both plasmablasts and long-lived plasma cells. Notably, although some disease-promoting features have been reported, results now demonstrate that certain monoclonal ACPAs therapeutically block arthritis and inflammation in mouse models. A wealth of functional studies using patient-derived polyclonal and monoclonal antibodies have provided evidence for pathogenic and protective effects of ACPAs in the context of arthritis. To understand the roles of ACPAs, one needs to consider their immunological properties by incorporating different facets such as rheumatoid arthritis B cell biology, environmental triggers and chronic antigen exposure. The emerging picture points to a complex role of citrulline-reactive autoantibodies, in which the diversity and dynamics of antibody clones could determine clinical progression and manifestations.

Exploring the impact of pathogenic microbiome in orthopedic diseases: machine learning and deep learning approaches

Osteoporosis, arthritis, and fractures are examples of orthopedic illnesses that not only significantly impair patients' quality of life but also complicate and raise the expense of therapy. It has been discovered in recent years that the pathophysiology of orthopedic disorders is significantly influenced by the microbiota. By employing machine learning and deep learning techniques to conduct a thorough analysis of the disease-causing microbiome, we can enhance our comprehension of the pathophysiology of many illnesses and expedite the creation of novel treatment approaches. Today's science is undergoing a revolution because to the introduction of machine learning and deep learning technologies, and the field of biomedical research is no exception. The genesis, course, and management of orthopedic disorders are significantly influenced by pathogenic microbes. Orthopedic infection diagnosis and treatment are made more difficult by the lengthy and imprecise nature of traditional microbial detection and characterization techniques. These cutting-edge analytical techniques are offering previously unheard-of insights into the intricate relationships between orthopedic health and pathogenic microbes, opening up previously unimaginable possibilities for illness diagnosis, treatment, and prevention. The goal of biomedical research has always been to improve diagnostic and treatment methods while also gaining a deeper knowledge of the processes behind the onset and development of disease. Although traditional biomedical research methodologies have demonstrated certain limits throughout time, they nevertheless rely heavily on experimental data and expertise. This is the area in which deep learning and machine learning approaches excel. The advancements in machine learning (ML) and deep learning (DL) methodologies have enabled us to examine vast quantities of data and unveil intricate connections between microorganisms and orthopedic disorders. The importance of ML and DL in detecting, categorizing, and forecasting harmful microorganisms in orthopedic infectious illnesses is reviewed in this work.

Rheumatoid arthritis and the intestinal microbiome: probiotics as a potential therapy

Rheumatoid arthritis (RA) is a systemic autoimmune disorder characterized by swollen joints, discomfort, stiffness, osteoporosis, and reduced functionality. Genetics, smoking, dust inhalation, high BMI, and hormonal and gut microbiota dysbiosis are all likely causes of the onset or development of RA, but the underlying mechanism remains unknown. Compared to healthy controls, patients with RA have a significantly different composition of gut microbiota. It is well known that the human gut microbiota plays a key role in the initiation, maintenance, and operation of the host immune system. Gut microbiota dysbiosis has local or systematic adverse effects on the host immune system, resulting in host susceptibility to various diseases, including RA. Studies on the intestinal microbiota modulation and immunomodulatory properties of probiotics have been reported, in order to identify their potential possibility in prevention and disease activity control of RA. This review summarized current studies on the role and potential mechanisms of gut microbiota in the development and progression of RA, as well as the preventative and therapeutic effects and potential mechanisms of probiotics on RA. Additionally, we proposed the challenges and difficulties in the application of probiotics in RA, providing the direction for the research and application of probiotics in the prevention of RA.

The role of microbiota on rheumatoid arthritis onset

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes inflammation and pain, which can lead to the loss of normal joint function. Although the exact cause of the disease is not yet fully understood, both environmental factors and genetics may play a role in its development. Moreover, research suggests microbiota contributes to the onset and progression of RA. People with RA show higher quantities of bacteria such as Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Prevotella copri, Proteus mirabilis, and Lactobacillus salivarius compared to healthy individuals. Conversely, studies propose that Lactobacillus casei, a probiotic bacterium with immunomodulatory properties, has beneficial effects for RA in murine and human models. Therefore, this work reviews the potential role of the gut microbiota in the development of RA and explores the feasibility of using probiotic bacteria as a supplementary treatment for this disease.

The causal impact of saturated fatty acids on rheumatoid arthritis: a bidirectional Mendelian randomisation study

Objective

The causal relationship between saturated fatty acids (SFAs) and rheumatoid arthritis (RA) remains poorly understood. This study aimed to determine whether SFAs are causally related to RA using Mendelian randomisation (MR) analyses.

Methods

Genome-wide association study (GWAS) summary data for RA (ukb-d-M13_RHEUMA) and SFAs (met-d-SFA) were obtained from the Integrative Epidemiology Unit OpenGWAS database. A bidirectional MR analysis was performed using a suite of algorithms, namely the MR-Egger, weighted median, simple mode, weighted mode, and inverse-variance weighted (IVW) algorithms, all integrated using the "MR" function. The robustness of the MR findings was further evaluated through sensitivity analyses, including heterogeneity, horizontal pleiotropy, and leave-one-out tests.

Results

The IVW algorithm in the forward MR analysis indicated a causal link between SFAs and RA (p = 0.025), identifying SFAs as a risk factor for RA (odds ratio = 1.001). Sensitivity analyses indicated no significant heterogeneity, horizontal pleiotropy, or severe bias, reinforcing the credibility of the forward MR results. However, the reverse MR analysis revealed that RA does not causally affect SFA levels (p = 0.195), and this finding was supported by corresponding sensitivity analyses.

Conclusion

The findings of this study substantiate the positive causal effect of SFAs on the incidence of RA through bidirectional MR analysis, thereby offering a consequential direction for future research on the diagnosis and treatment of RA.

Secrets and lies of host-microbial interactions: MHC restriction and trans-regulation of T cell trafficking conceal the role of microbial agents on the edge between health and multifactorial/complex diseases

Here we critically discuss data supporting the view that microbial agents (pathogens, pathobionts or commensals alike) play a relevant role in the pathogenesis of multifactorial diseases, but their role is concealed by the rules presiding over T cell antigen recognition and trafficking. These rules make it difficult to associate univocally infectious agents to diseases' pathogenesis using the paradigm developed for canonical infectious diseases. (Cross-)recognition of a variable repertoire of epitopes leads to the possibility that distinct infectious agents can determine the same disease(s). There can be the need for sequential infection/colonization by two or more microorganisms to develop a given disease. Altered spreading of infectious agents can determine an unwanted activation of T cells towards a pro-inflammatory and trafficking phenotype, due to differences in the local microenvironment. Finally, trans-regulation of T cell trafficking allows infectious agents unrelated to the specificity of T cell to modify their homing to target organs, thereby driving flares of disease. The relevant role of microbial agents in largely prevalent diseases provides a conceptual basis for the evaluation of more specific therapeutic approaches, targeted to prevent (vaccine) or cure (antibiotics and/or Biologic Response Modifiers) multifactorial diseases.

Nano-platform Strategies of Herbal Components for the Management of Rheumatoid Arthritis: A Review on the Battle for Next-Generation Formulations

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that initially affects small joints and then spreads to the bigger joints. It also affects other organs of the body such as lungs, eyes, kidneys, heart, and skin. In RA, there is destruction of cartilage and joints, and ligaments and tendons become brittle. Damage to the joints leads to abnormalities and bone degradation, which may be quite painful for the patient.

METHOD

The nano-carriers such as liposomes, phytosomes, nanoparticles, microcapsules, and niosomes are developed to deliver the encapsulated phytoconstituents to targeted sites for the better management of RA.

RESULTS

The phytoconstituents loaded nano-carriers have been used in order to increase bioavailability, stability and reduce the dose of an active compound. In one study, the curcumin-loaded phytosomes increase the bioavailability of curcumin and also provides relief from RA symptoms. The drug-loaded nano-carriers are the better option for the management of RA.

CONCLUSION

In conclusion, there are many anti-arthritic herbal and synthetic medicine available in the market that are currently used in the treatment of RA. However, chronic use of these medications may result in a variety of side effects. Because therapy for RA is frequently necessary for the rest of ones life. The use of natural products may be a better option for RA management. These phytoconstituents, however, have several disadvantages, including limited bioavailability, low stability, and the need for a greater dosage. These problems can be rectified by using nano-technology.

Epidemiology and Risk Factors for Rheumatoid Arthritis Development

Rheumatoid arthritis (RA) is a prevalent chronic inflammatory arthritis worldwide, significantly impacting patients and population health. The disease affects women primarily, with a female-to-male ratio of three to one. Its pathogenesis is multifactorial, including genetic and environmental risk factors. Epidemiological studies highlight the link between the environment and genetic susceptibility to RA. The so-called shared epitope is the most significant risk factor that seems to act synergetic with other environmental factors in the disease occurrence. In addition, recent findings suggest a potential role of new substantial environmental factors, such as the observed pollution of the planet's natural resources, on the susceptibility and progression of the disease. This review summarises the most decisive evidence on epidemiology and genetic, environmental, and lifestyle risk factors for RA. It shows that studying genetic and environmental factors in correlation could lead to prevention strategies that may impact the natural history of the disease.

Calprotectin blockade inhibits long-term vascular pathology following peritoneal dialysis-associated bacterial infection

Bacterial infections and the concurrent inflammation have been associated with increased long-term cardiovascular (CV) risk. In patients receiving peritoneal dialysis (PD), bacterial peritonitis is a common occurrence, and each episode further increases late CV mortality risk. However, the underlying mechanism(s) remains to be elucidated before safe and efficient anti-inflammatory interventions can be developed. Damage-Associated Molecular Patterns (DAMPs) have been shown to contribute to the acute inflammatory response to infections, but a potential role for DAMPs in mediating long-term vascular inflammation and CV risk following infection resolution in PD, has not been investigated. We found that bacterial peritonitis in mice that resolved within 24h led to CV disease-promoting systemic and vascular immune-mediated inflammatory responses that were maintained up to 28 days. These included higher blood proportions of inflammatory leukocytes displaying increased adhesion molecule expression, higher plasma cytokines levels, and increased aortic inflammatory and atherosclerosis-associated gene expression. These effects were also observed in infected nephropathic mice and amplified in mice routinely exposed to PD fluids. A peritonitis episode resulted in elevated plasma levels of the DAMP Calprotectin, both in PD patients and mice, here the increase was maintained up to 28 days. In vitro, the ability of culture supernatants from infected cells to promote key inflammatory and atherosclerosis-associated cellular responses, such as monocyte chemotaxis, and foam cell formation, was Calprotectin-dependent. In vivo, Calprotectin blockade robustly inhibited the short and long-term peripheral and vascular consequences of peritonitis, thereby demonstrating that targeting of the DAMP Calprotectin is a promising therapeutic strategy to reduce the long-lasting vascular inflammatory aftermath of an infection, notably PD-associated peritonitis, ultimately lowering CV risk.

The uni-directional association of atopic dermatitis and rheumatoid arthritis: a systematic review and meta-analysis

Atopic dermatitis (AD) is a highly pruritic, inflammatory skin disease with a strong immune component. Rheumatoid arthritis (RA) is a systemic autoimmune disease that causes synovitis and destruction of small joints. Researchers have attempted to quantify an association between both diseases with mixed conclusions. This systematic review and meta-analysis will study the association between AD and RA. Additionally, we conducted a systematic review between AD and other arthritic conditions including osteoarthritis (OA), psoriatic arthritis (PsA), and juvenile idiopathic arthritis (JIA). Medline, Web of Science, Cochrane, and EMBASE databases were searched for relevant studies from inception to March 2021. Observational studies examining relationships between AD and arthritic conditions were selected. 2539 studies were screened; nine were found suitable for quantitative analysis, all of which examined AD and RA. All studies had low risk of bias as determined by the Newcastle-Ottawa Scale. Patients with RA did not have significantly increased odds of comorbid AD. These findings were consistent across multiple study designs. However, patients with AD had significantly increased odds of comorbid RA. There were not enough studies identified to perform quantitative analysis between AD and other arthritic conditions. Two studies, one on JIA and one PsA, found no association with AD. Two studies on AD and OA had conflicting results. The present study provides definitive evidence of increased odds of comorbid RA in AD patients. There were no such increased odds of comorbid AD in RA patients. No such association was found between AD and PsA, OA or JIA.

Progression of pre-rheumatoid arthritis to clinical disease of joints: Potential role of mesenchymal stem cells

Rheumatoid arthritis (RA) related autoimmunity is developed at mucosal sites due to the interplay between genetic risk factors and environmental triggers. The pre-RA phase that leads to anti-citrullinated protein antibodies, rheumatoid factor, and other autoantibodies spread in the systemic circulation may not affect articular tissue for years until a mysterious second hit triggers the localization of RA-related autoimmunity in joints. Several players in the joint microenvironment mediate the synovial innate and adaptive immunological processes, eventually leading to clinical synovitis. There still exists a gap in the early phase of RA pathogenesis, i.e., the progression of diseases from the systemic circulation to joints. The lack of better understanding of these events results in the inability to answer questions about why only after a certain point of time the disease appears in joints and why in some cases, it simply remains latent and doesn't affect joints at all. In the current review, we focused on the immunomodulatory and regenerative role of mesenchymal stem cells and associated exosomes in RA pathology. We also highlighted the age-related dysregulations in activities of mesenchymal stem cells and how that might trigger homing of systemic autoimmunity to joints.

Dysbiotic but nonpathogenic shift in the fecal mycobiota of patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is closely associated with the oral and gut microbiomes. Fungal cell wall components initiate inflammatory arthritis in mouse models. However, little is known regarding the role of the fungal community in the pathogenesis of RA. To evaluate the association between RA and the gut microbiome, investigations of bacterial and fungal communities in patients with RA are necessary. Therefore, we investigated the compositions and associations of fecal bacterial and fungal communities in 30 healthy controls and 99 patients with RA. The relative abundances of Bifidobacterium and Blautia decreased, whereas the relative abundance of Streptococcus increased, in patients with RA. The relative abundance of Candida in the fecal fungal community was higher in patients with RA than in healthy controls, while the relative abundance of Aspergillus was higher in healthy controls than in patients with RA. Candida species-specific gene amplification showed that C. albicans was the most abundant species of Candida. Ordination analysis and random forest classification models supported the findings of structural changes in bacterial and fungal communities. Aspergillus was the core fecal fungal genus in healthy controls, although Saccharomyces spp. are typically predominant in Western cohorts. In addition, bacterial-fungal association analyses showed that the hub node had shifted from fungi to bacteria in patients with RA. The finding of fungal dysbiosis in patients with RA suggests that fungi play critical roles in the fecal microbial communities and pathogenesis of RA.

Co-amorphous Systems of Sinomenine with Platensimycin or Sulfasalazine: Physical Stability and Excipient-Adjusted Release Behavior

There is strong interest to develop affordable treatments for the infection-associated rheumatoid arthritis (RA). Here, we present a drug-drug co-amorphous strategy against RA and the associated bacterial infection by the preparation and characterization of two co-amorphous systems of sinomenine (SIN) with platensimycin (PTM) or sulfasalazine (SULF), two potent antibiotics. Both of them were comprehensively characterized using powder X-ray diffraction, temperature-modulated differential scanning calorimetry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The co-amorphous forms of SIN-PTM and SIN-SULF exhibited high T_gs at 139.10 ± 1.0 and 153.3 ± 0.2 °C, respectively. After 6 months of accelerated tests and 1 month of drug-excipient compatibility experiments, two co-amorphous systems displayed satisfactory physical stability. The formation of salt and strong intermolecular interactions between SIN and PTM or SULF, as well as the decreased molecular mobility in co-amorphous systems, may be the intrinsic mechanisms underlying the excellent physical stability of both co-amorphous systems. In dissolution tests, two co-amorphous systems displayed distinct reduced SIN-accumulative releases (below 20% after 6 h of release experiments), which may lead to its poor therapeutic effect. Hence, we demonstrated a controlled release strategy for SIN by the addition of a small percentage of polymers and a small-molecule surfactant to these two co-amorphous samples as convenient drug excipients, which may also be used to improve the unsatisfactory dissolution behaviors of the previously reported SIN co-amorphous systems. Several hydrogen bonding interactions between SIN and PTM or SULF could be identified in NMR experiments in DMSO-d₆, which may be underlying reasons of decreased dissolution behaviors of both co-amorphous forms. These drug-drug co-amorphous systems could be a potential strategy for the treatment of infection-associated RA.

Tofacitinib enhances IGF1 via inhibiting STAT6 transcriptionally activated-miR-425-5p to ameliorate inflammation in RA-FLS

Rheumatoid arthritis (RA) is a systemic autoimmune disease, which has been reported closely associated with the dysfunction of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. This study aims to explore the potential therapeutic effect of Tofacitinib, a putative JAK/STAT inhibitor, in RA. Tofacitinib suppressed proliferation and accelerated apoptosis of rheumatoid arthritis synovial fibroblasts (RA-FLS) as confirmed by CCK-8, EdU and Western blot assays. Tofacitinib significantly inhibited expression of pro-inflammatory factors including tumor necrosis factor-α (TNF-α), vascular endothelial growth factor A, matrix metalloproteinase 1, matrix metalloproteinase 3, interleukin-6 and interferon gamma in RA-FLS cells. mechanistically, tofacitinib decreased signal transducer and activator of transcription 6 (STAT6), which transcriptionally activates miR-425-5p, and thus increased insulin like growth factor 1 (IGF1) expression, a target of miR-425-5p in RA-FLS. Overexpression of STAT6 restored the expression of pro-inflammatory factors and proliferation inhibited by Tofacitinib in RA-FLS. Overall, Tofacitinib exerted inhibitory effect on proliferation and inflammation of RA-FLS through modulating STAT6/miR-425-5p/IGF1 signal axis. These findings shed light on the novel strategies for improving RA.

The lack of association between PADI4_94 or PADI4_104 polymorphisms and RF, ACPA and anti-PAD4 in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that leads to chronic inflammation of synovial tissue, ultimately causing joint damage, disability, and premature mortality. The peptidylarginine deiminase (PAD) family of proteins is involved in the production of anticitrullinated peptide antibodies (ACPA), which are clinically relevant markers of RA. ACPA recognizes citrullinated proteins generated mainly by PAD4. Polymorphisms of the PADI4 gene have been associated with RA in Asian populations, but in Europeans these associations are still difficult to estimate. A total of 147 subjects, 122 patients with RA, 52 ± 12.3 aged, 84.4% women and 25 healthy controls, 53 ± 8.4 aged, 72% women were enrolled in the study. Two single nucleotide polymorphisms (SNPs) of the PADI4 gene (PADI4_94, rs2240340 and PADI4_104, rs1748033) were genotyped using a real-time polymerase chain reaction. Genetic models (co-dominant-1 and 2, dominant, over-dominant, and recessive) were applied to find the associations between genotypes and ACPA as well as PAD4 antibodies (anti-PAD4) levels. We found no relationship between the distribution of genotypes in different genetic models and the levels of anti-PAD4, ACPA and RF antibodies. There were also no differences with respect to the haplotypes. Genetic variants PADI4_94 and PADI4_104 may not be clinically relevant as prognostic factors in patients with established RA.

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

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

Peptidylarginine Deiminase 2 in Host Immunity: Current Insights and Perspectives

Peptidylarginine deiminases (PADs) are a group of enzymes that catalyze post-translational modifications of proteins by converting arginine residues into citrullines. Among the five members of the PAD family, PAD2 and PAD4 are the most frequently studied because of their abundant expression in immune cells. An increasing number of studies have identified PAD2 as an essential factor in the pathogenesis of many diseases. The successes of preclinical research targeting PAD2 highlights the therapeutic potential of PAD2 inhibition, particularly in sepsis and autoimmune diseases. However, the underlying mechanisms by which PAD2 mediates host immunity remain largely unknown. In this review, we will discuss the role of PAD2 in different types of cell death signaling pathways and the related immune disorders contrasted with functions of PAD4, providing novel therapeutic strategies for PAD2-associated pathology.

In vitro evaluation of disease-modifying antirheumatic drugs against rheumatoid arthritis associated pathogens of the oral microflora

OBJECTIVES

In the past, the human microbiome has consistently been associated with rheumatoid arthritis (RA) and disease activity. Here, we investigate the antimicrobial activity of disease-modifying antirheumatic drugs (DMARDs) against typical representatives of the oral microflora that have been associated with RA.

METHODS

DMARDs were screened for antimicrobial activity against bacteria that are associated with the pathogenesis of the disease and/or frequently isolated from the oral microflora of patients with RA. Screening was done by an agar diffusion assay and minimum inhibitory concentrations (MICs) of antimicrobial active substances were then determined by broth dilution.

RESULTS

Aurothiomalate and sulfasalazine demonstrated broad-spectrum antimicrobial activity, but with MICs ranging from 18 to >280 µg/mL and 150 to >600 µg/mL, respectively, only at supratherapeutic concentrations. Methotrexate showed antimicrobial activity only against Fusobacterium nucleatum and Viridans streptococci. The corresponding MICs were 3.75 to >30 µg/mL and 0.5-15 µg/mL, respectively, thus at least for streptococci, within the therapeutically achievable range. No other DMARD tested showed antimicrobial activity in the agar diffusion screening assay.

CONCLUSION

Methotrexate, sulfasalazine and aurothiomalate showed antimicrobial activity against a broad spectrum of RA associated pathogens of the oral microflora. While methotrexate showed relevant antimicrobial activity, and to a more limited extent aurothiomalate, sulfasalazine was active only at far supratherapeutic systemic concentrations. Nevertheless, given the highly species-dependent antimicrobial activity and the multiple ways it can affect the human microbiome, our results suggest a link between antimicrobially active antirheumatic drugs and their potential effect in the treatment of RA.

Porphyromonas gingivalis exacerbates ulcerative colitis via Porphyromonas gingivalis peptidylarginine deiminase

Ulcerative Colitis (UC) has been reported to be related to Porphyromonas gingivalis (P. gingivalis). Porphyromonas gingivalis peptidylarginine deiminase (PPAD), a virulence factor released by P. gingivalis, is known to induce inflammatory responses. To explore the pathological relationships between PPAD and UC, we used homologous recombination technology to construct a P. gingivalis strain in which the PPAD gene was deleted (Δppad) and a Δppad strain in which the PPAD gene was restored (comΔppad). C57BL/6 mice were orally gavaged with saline, P. gingivalis, Δppad, or comΔppad twice a week for the entire 40 days (days 0-40), and then, UC was induced by dextran sodium sulfate (DSS) solution for 10 days (days 31-40). P. gingivalis and comΔppad exacerbated DDS-induced colitis, which was determined by assessing the parameters of colon length, disease activity index, and histological activity index, but Δppad failed to exacerbate DDS-induced colitis. Flow cytometry and ELISA revealed that compared with Δppad, P. gingivalis, and comΔppad increased T helper 17 (Th17) cell numbers and interleukin (IL)-17 production but decreased regulatory T cells (Tregs) numbers and IL-10 production in the spleens of mice with UC. We also cocultured P. gingivalis, Δppad, or comΔppad with T lymphocytes in vitro and found that P. gingivalis and comΔppad significantly increased Th17 cell numbers and decreased Treg cell numbers. Immunofluorescence staining of colon tissue paraffin sections also confirmed these results. The results suggested that P. gingivalis exacerbated the severity of UC in part via PPAD.

The Potential Role of Human Papillomavirus Infection in Bell's Palsy: A Hypothesis-Generating Study Based on a Nationwide Cohort

Objective: Our purpose was to investigate whether people with a previous human papillomavirus (HPV) infection were associated with an increased risk of Bell's palsy (BP).

Methods: By using Taiwan population-based data, patients aged > 18 years with HPV infection (n = 22,260) from 2000 to 2012 were enrolled and compared with control subjects who had never been diagnosed with an HPV infection at a 1:4 ratio matched by sex, age, index date, and co-morbidities (n = 89,040). The index date was the first date of HPV diagnosis. All the patients were tracked until the occurrence of BP. Cox proportional hazards regression was applied to estimate the hazard ratios (HRs) for the development of BP in both groups.

Results: The HPV group had 1.25 [95% confidence interval (CI) = 1.03–1.51] times higher risk of BP compared with the non-HPV group after adjusting for sex, age, and co-morbidities. The association of HPV and BP was significant in the sensitivity analyses. In the subgroup analysis, the impact of HPV infection on the risk of BP was more pronounced in the elderly > 50 years [adjusted hazard ratio (aHR) =1.86; 95% CI = 1.37–2.52], hypertension (aHR = 1.65; 95% CI = 1.17–2.31), and chronic obstructive pulmonary disease (aHR = 2.14, 95% CI 1.333.43) subgroups.

Conclusions: Patients with HPV infection have a higher risk of subsequent BP compared with non-HPV patients. More rigorous studies are needed to confirm if and how specific HPV genotypes are associated with BP and the possible role of vaccines in disease prevention.

Transcription factor EB promotes rheumatoid arthritis of Sprague-Dawley rats via regulating autophagy

This study investigated the effect of autophagy-related gene transcription factor EB (TFEB) on the rheumatoid arthritis (RA) and explored whether TFEB regulated RA by autophagy. The Sprague-Dawley rats were divided into two groups (n = 6). The rats were stimulated with the mixture of the type II collagen and Freund's adjuvant or PBS at the root of the tail. Results showed that swollen and deformed joints were discovered, the levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were elevated, and hematoxylin and eosin staining showed the inflammatory cells infiltrate the synovial tissue in the RA rats, compared to the control group. Immunohistochemistry displayed that the expressions of TFEB and LC3B increased in the synovial tissues of RA rats, whereas p62 decreased. The silence of TFEB in the RA-fibroblast-like synoviocytes (RA-FLS) decreased the protein expressions of LC3B, compared to the siRNA NC group. Meanwhile, the activity of FLS was raised, whereas the levels of TNF-α and IL-6 decreased in RA-FLS with TFEB knockdown. In conclusion, our study revealed that TFEB plays a crucial role in the progress of RA by regulating autophagy, which might provide novel targets for the therapy of RA.

Patients with comorbid rheumatoid arthritis are predisposed to peritonsillar abscess: real-world evidence

PURPOSE

The peritonsillar abscess (PTA)-rheumatoid arthritis (RA) association remains unclear. Here, the effects of RA on PTA incidence and prognosis are elucidated.

METHODS

We compared PTA incidence and prognosis of 30,706 RFCIP-registered patients with RA (RA cohort) with matched individuals without RA from another database of 1 million randomly selected people representing Taiwan's population (non-RA cohort).

RESULTS

The RA cohort had significantly higher PTA incidence [incidence rate ratio (IRR) (95% CI) 1.73 (1.10-2.71), P = 0.017) and cumulative incidence (P = 0.016, Kaplan-Meier curves). Cox regression analyses demonstrated RA cohort to have an estimated 1.72-fold increased PTA risk (95% CI 1.09-2.69, P = 0.019). PTA was more likely within the first 5 years of RA diagnosis (for < 1, 1-5, and ≥ 5 postdiagnosis years, IRRs: 2.67, 2.31, and 1.10, respectively, and P = 0.063, 0.021, and 0.794, respectively; average onset duration: 4.3 ± 3.3 years after RA diagnosis). PTA increased length of hospital stay significantly and risk of complication with deep neck infection nonsignificantly [6.5 ± 4.5 vs 4.6 ± 2.8 days (P = 0.045) and 18.52% vs 7.81% (P = 0.155), respectively]. Moreover, RA-cohort patients not receiving RA therapy exhibited 5.06-fold higher PTA risk than those receiving RA-related therapy (95% CI 1.75-14.62, P = 0.003).

CONCLUSIONS

In patients with RA, PTA incidence is the highest within 5 years of RA diagnosis, and RA therapy is essential for reducing PTA risk.

LEVEL OF EVIDENCE

4.

The Role of Nutritional Factors and Intestinal Microbiota in Rheumatoid Arthritis Development

Evidence about the role of nutritional factors and microbiota in autoimmune diseases, and in rheumatoid arthritis (RA) in particular, has grown in recent years, however many controversies remain. The aim of this review is to summarize the role of nutrition and of the intestinal microbiota in the development of RA. We will focus on selected dietary patterns, individual foods and beverages that have been most consistently associated with RA or with the occurrence of systemic autoimmunity associated with RA. We will also review the evidence for a role of the intestinal microbiota in RA development. We propose that diet and digestive microbiota should be considered together in research, as they interact and may both be the target for future preventive interventions in RA.

Zinc and Cadmium in the Aetiology and Pathogenesis of Osteoarthritis and Rheumatoid Arthritis

Osteoarthritis (OA) and rheumatoid arthritis (RA) are inflammatory articular conditions with different aetiology, but both result in joint damage. The nutritionally essential metal zinc (Zn²⁺) and the non-essential metal cadmium (Cd²⁺) have roles in these arthritic diseases as effectors of the immune system, inflammation, and metabolism. Despite both metal ions being redox-inert in biology, they affect the redox balance. It has been known for decades that zinc decreases in the blood of RA patients. It is largely unknown, however, whether this change is only a manifestation of an acute phase response in inflammation or relates to altered availability of zinc in tissues and consequently requires changes of zinc in the diet. As a cofactor in over 3000 human proteins and as a signaling ion, zinc affects many pathways relevant for arthritic disease. How it affects the diseases is not just a question of zinc status, but also an issue of mutations in the many proteins that maintain cellular zinc homoeostasis, such as zinc transporters of the ZIP (Zrt-/Irt-like protein) and ZnT families and metallothioneins, and the multiple pathways that change the expression of these proteins. Cadmium interferes with zinc's functions and there is increased uptake under zinc deficiency. Remarkably, cadmium exposure through inhalation is now recognized in the activation of macrophages to a pro-inflammatory state and suggested as a trigger of a specific form of nodular RA. Here, we discuss how these metal ions participate in the genetic, metabolic, and environmental factors that lead to joint destruction. We conclude that both metal ions should be monitored routinely in arthritic disease and that there is untapped potential for prognosis and treatment.

Antibodies Isolated from Rheumatoid Arthritis Patients against Lysine-Containing Proteus mirabilis O3 (S1959) Lipopolysaccharide May React with Collagen Type I

Most rheumatic diseases, including rheumatoid arthritis (RA), are characterized by immune disorders that affect antibody activity. In the present study, using Dot blot and ELISA assay, we showed that patients with rheumatic disease produced significantly more antibodies against lipopolysaccharide (LPS) P. mirabilis O3 compared to healthy donors (p < 0.05), and affinity purified antibodies against LPS O3 may cross-react with collagen type I. It was demonstrated that purified of antibodies isolated from RA patients sera, reacted stronger with the collagen than healthy donors (p = 0.015), and cross-reaction was correlated with level of anti-citrullinated peptide antibodies (r = 0.7, p = 0.003). Moreover, using six different lipopolysaccharides were demonstrated the significant correlations in sera reactivity among lysine-containing lipopolysaccharides observed in patients’ sera (p < 0.05). Using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) it was shown that unique wavenumbers of sera spectra correlate with reactivity with lipopolysaccharides allowing distinguish patients from healthy blood donors. Antibodies adsorption by synthetic antigens shows that in patients’ group anti-LPS O3 antibodies can be adsorbed by both amides of galacturonic acid and lysine or threonine, which suggests less specificity of antibodies binding with non-carbohydrate LPS component. The observed correlations suggest that non-carbohydrate components of LPS may be an important epitope for less specific anti-LPS antibodies, which might lead to cross-reactions and affect disease development.

Regulating Gut Microbiome: Therapeutic Strategy for Rheumatoid Arthritis During Pregnancy and Lactation

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation and bone destruction. Microbial infection is considered to be the most important inducement of RA. The pregnancy planning of women in childbearing age is seriously affected by the disease activity of RA. Gut microbiome, related to immunity and inflammatory response of the host. At present, emerging evidence suggested there are significant differences in the diversity and abundance of gut microbiome during pregnancy and lactation, which may be associated with the fluctuation of RA disease activity. Based on these research foundations, we pioneer the idea of regulating gut microbiome for the treatment of RA during pregnancy and lactation. In this review, we mainly introduce the potential treatment strategies for controlling the disease activity of RA based on gut microbiome during pregnancy and lactation. Besides, we also briefly generalize the effects of conventional anti-rheumatic drugs on gut microbiome, the effects of metabolic changes during pregnancy on gut microbiome, alteration of gut microbiome during pregnancy and lactation, and the effects of anti-rheumatic drugs commonly used during pregnancy and lactation on gut microbiome. These will provide a clear knowledge framework for researchers in immune-related diseases during pregnancy. Regulating gut microbiome may be a potential and effective treatment to control the disease activity of RA during pregnancy and lactation.

Mini-Review: Human Microbiome and Rheumatic Diseases

Rheumatoid arthritis and spondyloarthropathy are the most common inflammatory rheumatic diseases. As the human microbiome is involved in the immune homeostasis, it has the potential to be a key factor in the development of autoimmune diseases and rheumatic diseases. In this article, we review the role of various human microbiota on the pathogenesis of rheumatic diseases, focusing on spondylarthritis and rheumatoid arthritis.

Infection With Clostridioides difficile Attenuated Collagen-Induced Arthritis in Mice and Involved Mesenteric Treg and Th2 Polarization

Objectives

Rheumatoid arthritis is an autoimmune disease with multifactorial etiopathogenesis. Among the environmental factors, mucosal infections and the inducing pathobionts are gaining increasing attention. We here set out to explore the gut-joint-axis and the impact of Clostridioides difficile infection on subsequent arthritis.

Methods

We combined C. difficile infection in DBA/1J × B10.Q F1 mice with collagen induced arthritis (CIA). Mice were infected via oral gavage and infection was monitored by weight loss, colonic histology, and antibodies against bacteria. Scoring of arthritis was performed macroscopically. Intestinal microbiomes were analyzed and immune responses were monitored via quantification of transcription factor-specific mRNA isolated from the inguinal and mesenteric lymph nodes.

Results

Infection with C. difficile VPI 10463 resulted in significant weight loss and severe colitis yet accelerated the reversal towards the original microbiome after antibiotic treatment. Spontaneous clearance of VPI 10463 infection reduced the incidence of subsequent CIA and led to mesenteric T_reg and T_h2 polarization. However, this attenuating effect was abrogated if VPI 10463 was eradicated via vancomycin followed by fecal microbiota transplantation. Moreover, VPI 10463 infection following the onset of CIA lacked therapeutic potential.

Conclusion

Our results demonstrate that infection with C. difficile VPI10463 induced an inflammation of the gut that protected from subsequent arthritis development in mice. Both, microbial changes to the gut and immune cell mobilization and/or polarization may have contributed to arthritis protection. The prospect of potential therapeutic benefits resulting from C. difficile infections or some byproduct thereof call for further experiments that help elucidate exact mechanisms.

Reproductive Tract Infection Among Women Suffering From Rheumatoid Arthritis in India: A Clinical-Based, Cross-Sectional Study

Background: Much research has been done on reproductive tract infections (RTIs), but no study exists about RTIs among rheumatoid arthritis women. Objectives: This study investigated the prevalence and risk factors of RTIs among reproductive-aged women with rheumatoid arthritis in Pune, India. Methods: This clinical-based, cross-sectional study enrolled a sample of 400 consenting Indian women aged 15 -49 years with a history of at least three months’ rheumatoid arthritis referring to a popular community center. Patients were interviewed comprehensively using previously validated relevant questionnaires. Women underwent gynecological examinations and vaginal smears (wet mount) by a microbiologist to diagnose candidiasis, bacterial vaginosis, and trichomoniasis. Syphilis serological testing was performed for the study population. Results: The prevalence obtained was 39.3%. Infection with bacterial vaginosis was 32.0%, Candidiasis 6.5%, and trichomoniasis 0.8%. Syphilis seroconversion was not observed. Adjusting for confounding factors in logistic regression showed that four factors remained significant, including age under 30 years [AOR: 2.4, 95% CI: 1.2 - 4.9], living in a crowded and small one-room house [AOR: 2.5, 95% CI: 1.2 - 5.1] , improper linen for menstruation bleeding [AOR: 1.9, 95% CI: 1.1 - 3.3], and oral disease-modifying anti-rheumatic drugs [AOR: 3.96, 95% CI: 1.9 - 7.9]. Conclusions: This study demonstrated a large burden of RTIs in women suffering from rheumatoid arthritis. Regular screening algorithms for RTIs are urgently required to prevent neglect and improve overall standard care in rheumatology practice. The presence of an oral disease-modifying anti-rheumatic drug as a risk factor shows that more investigation is necessary in this case.

The Role of the Microbiome in Driving RA-Related Autoimmunity

Once referred to as "normal commensal flora" the human microbiome plays an integral role between health and disease. The host mucosal surface replete with a multitude of immune cells is a vast arena constantly sensing and responding to antigen presentation and microbial by-products. It is this key role that may allow the microbiome to prime or protect the host from autoimmune disease. Rheumatoid arthritis (RA) is a chronic, disabling inflammatory condition characterized by a complex multifactorial etiology. The presence of certain genetic markers has been proven to increase susceptibility to RA however it does not guarantee disease development. Given low concordance rates demonstrated in monozygotic twin studies there is a clear implication for the involvement of external players in RA pathogenesis. Since the historical description of rheumatoid factor, numerous additional autoantibodies have been described in the sera of RA patients. The presence of anti-cyclic citrullinated protein antibody is now a standard test, and is associated with a more severe disease course. Interestingly these antibodies are detectable in patient's sera long before the clinical signs of RA occur. The production of autoantibodies is driven by the lack of tolerance of the immune system, and how tolerance is broken is a crucial question for understanding RA development. Here we review current literature on the role of the microbiome in RA development including periodontal, gut and lung mucosa, with particular focus on proposed mechanisms of host microbiome interactions. We discuss the use of Mendelian randomization to assign causality to the microbiome and present considerations for future studies.

Current and novel therapeutic targets in the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA), a multifactorial disease characterized by synovitis, cartilage destruction, bone erosion, and periarticular decalcification, finally results in impairment of joint function. Both genetic and environmental factors are risk factors in the development of RA. Unwanted side effects accompany most of the current treatment strategies, and around 20-40% of patients with RA do not clinically benefit from these treatments. The unmet need for new treatment options for RA has prompted research in the development of novel agents acting through physiologically and pharmacologically relevant targets. Here we discuss in detail three critical pathways, Janus kinase/signal transducer and activator of transcription (JAK/STAT), Th17, and hypoxia-inducible factor (HIF), and their roles as unique therapeutic targets in the field of RA. Some of the less developed but potential targets like nucleotide-binding and oligomerization domain-like receptor containing protein 3 (NLRP3) inflammasome and histone deacetylase 1 (HDAC1) are also discussed.

Differential Accumulation and Activation of Monocyte and Dendritic Cell Subsets in Inflamed Synovial Fluid Discriminates Between Juvenile Idiopathic Arthritis and Septic Arthritis

Despite their distinct etiology, several lines of evidence suggest that innate immunity plays a pivotal role in both juvenile idiopathic arthritis (JIA) and septic arthritis (SA) pathophysiology. Indeed, monocytes and dendritic cells (DC) are involved in the first line of defense against pathogens and play a critical role in initiating and orchestrating the immune response. The aim of this study was to compare the number and phenotype of monocytes and DCs in peripheral blood (PB) and synovial fluid (SF) from patients with JIA and SA to identify specific cell subsets and activation markers associated with pathophysiological mechanisms and that could be used as biomarkers to discriminate both diseases. The proportion of intermediate and non-classical monocytes in the SF and PB, respectively, were significantly higher in JIA than in SA patients. In contrast the proportion of classical monocytes and their absolute numbers were higher in the SF from SA compared with JIA patients. Higher expression of CD64 on non-classical monocyte was observed in PB from SA compared with JIA patients. In SF, higher expression of CD64 on classical and intermediate monocyte as well as higher CD163 expression on intermediate monocytes was observed in SA compared with JIA patients. Moreover, whereas the number of conventional (cDC), plasmacytoid (pDC) and inflammatory (infDC) DCs was comparable between groups in PB, the number of CD141⁺ cDCs and CD123⁺ pDCs in the SF was significantly higher in JIA than in SA patients. CD14⁺ infDCs represented the major DC subset in the SF of both groups with potent activation assessed by high expression of HLA-DR and CD86 and significant up-regulation of HLA-DR expression in SA compared with JIA patients. Finally, higher activation of SF DC subsets was monitored in SA compared with JIA with significant up-regulation of CD86 and PDL2 expression on several DC subsets. Our results show the differential accumulation and activation of innate immune cells between septic and inflammatory arthritis. They strongly indicate that the relative high numbers of CD141⁺ cDC and CD123⁺ pDCs in SF are specific for JIA while the over-activation of DC and monocyte subsets is specific for SA.

Cell-Type Targeted NF-kappaB Inhibition for the Treatment of Inflammatory Diseases

Deregulated NF-k activation is not only involved in cancer but also contributes to the pathogenesis of chronic inflammatory diseases like rheumatoid arthritis (RA) and multiple sclerosis (MS). Ideally, therapeutic NF-KappaB inhibition should only take place in those cell types that are involved in disease pathogenesis to maintain physiological cell functions in all other cells. In contrast, unselective NF-kappaB inhibition in all cells results in multiple adverse effects, a major hindrance in drug development. Hitherto, various substances exist to inhibit different steps of NF-kappaB signaling. However, powerful tools for cell-type specific NF-kappaB inhibition are not yet established. Here, we review the role of NF-kappaB in inflammatory diseases, current strategies for drug delivery and NF-kappaB inhibition and point out the "sneaking ligand" approach. Sneaking ligand fusion proteins (SLFPs) are recombinant proteins with modular architecture consisting of three domains. The prototype SLC1 binds specifically to the activated endothelium and blocks canonical NF-kappaB activation. In vivo, SLC1 attenuated clinical and histological signs of experimental arthritides. The SLFP architecture allows an easy exchange of binding and effector domains and represents an attractive approach to study disease-relevant biological targets in a broad range of diseases. In vivo, SLFP treatment might increase therapeutic efficacy while minimizing adverse effects.

Considerations for improving quality of care of patients with rheumatoid arthritis and associated comorbidities

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disorder with a global prevalence of approximately 0.5-1%. Patients with RA are at an increased risk of developing comorbidities (eg, cardiovascular disease, pulmonary disease, diabetes and depression). Despite this, there are limited recommendations for the management and implementation of associated comorbidities. This study aimed to identify good practice interventions in the care of RA and associated comorbidities.

METHODS

A combination of primary research (180+ interviews with specialists across 12 European rheumatology centres) and secondary research (literature review of existing publications and guidelines/recommendations) were used to identify challenges in management and corresponding good practice interventions. Findings were prioritised and reviewed by a group of 18 rheumatology experts including rheumatologists, comorbidity experts, a patient representative and a highly specialised nurse.

RESULTS

Challenges throughout the patient pathway (including delays in diagnosis and referral, shortage of rheumatologists, limited awareness of primary care professionals) and 18 good practice interventions were identified in the study. The expert group segmented and prioritised interventions according to three distinct stages of the disease: (1) suspected RA, (2) recent diagnosis of RA and (3) established RA. Examples of good practice interventions included enabling self-management (self-monitoring and disease management support, for example, lifestyle adaptations); early arthritis clinic; rapid access to care (online referral, triage, ultrasound-guided diagnosis); dedicated comorbidity specialists; enhanced communication with primary care (hotline, education sessions); and integrating patient registries into daily clinical practice.

CONCLUSION

Learning from implementation of good practice interventions in centres across Europe provides an opportunity to more widely improved care for patients with RA and associated comorbidities.

Porphyromonas gingivalis, a Long-Range Pathogen: Systemic Impact and Therapeutic Implications

Periodontitis is an inflammatory disease associated with a dysbiosis of the oral flora characterized by a chronic sustained inflammation leading to destruction of tooth-supporting tissues. Over the last decade, an association between periodontitis and systemic disorders such as cardiovascular diseases, rheumatoid arthritis and obesity has been demonstrated. The role of periodontal pathogens, notably Porphyromonas gingivalis (P. gingivalis), in the onset or exacerbation of systemic diseases has been proposed. P. gingivalis expresses several virulence factors that promote its survival, spreading, and sustaining systemic inflammation. Recently, the impact of periodontitis on gut dysbiosis has also been suggested as a potential mechanism underlying the systemic influence of periodontitis. New therapeutic strategies for periodontitis and other dysbiotic conditions, including the use of beneficial microbes to restore healthy microbial flora, may pave the way to improved therapeutic outcomes and more thorough patient management.

Methylation Pattern of the SOCS3 and IL6R Promoters in Rheumatoid Arthritis

Interleukin-6 (IL-6) plays an essential function in the development of rheumatoid arthritis (RA), mainly through its proinflammatory effect, which may lead to joint destruction. The genes encoding IL-6 receptor (IL6R) and suppressor of cytokine signaling 3 (SOCS3) play a key role in the IL-6 signaling pathway, but their epigenetic regulation remains unclear. The aim of the study was to investigate how the presence of methylation in the SOCS3 and IL6R promoters is associated with the morbidity and severity of RA. A total of 146 unrelated individuals, 122 with RA and 24 healthy controls, were enrolled in the study. All subjects were genotyped with regard to the rs4969168 and rs4969170 polymorphisms in the SOCS3 gene and the rs2228145 and rs4129267 polymorphisms in IL6R. The methylation study included 52 patients with RA and 24 healthy controls. Qualitative real-time methylation-specific PCR was used to evaluate methylation status. We found no differences between patients and healthy controls in the methylation pattern in the IL6R and SOCS3 promoter regions and in variants frequency. The methylation profiles of the SOCS3 and IL6R promoters do not support the hypothesis that the genes SOCS3 and IL6R involved in the JAK-STAT signaling pathway are epigenetically deregulated in whole blood.

Update on the Pathomechanism, Diagnosis, and Treatment Options for Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that involves multiple joints bilaterally. It is characterized by an inflammation of the tendon (tenosynovitis) resulting in both cartilage destruction and bone erosion. While until the 1990s RA frequently resulted in disability, inability to work, and increased mortality, newer treatment options have made RA a manageable disease. Here, great progress has been made in the development of disease-modifying anti-rheumatic drugs (DMARDs) which target inflammation and thereby prevent further joint damage. The available DMARDs are subdivided into (1) conventional synthetic DMARDs (methotrexate, hydrochloroquine, and sulfadiazine), (2) targeted synthetic DMARDs (pan-JAK- and JAK1/2-inhibitors), and (3) biologic DMARDs (tumor necrosis factor (TNF)-α inhibitors, TNF-receptor (R) inhibitors, IL-6 inhibitors, IL-6R inhibitors, B cell depleting antibodies, and inhibitors of co-stimulatory molecules). While DMARDs have repeatedly demonstrated the potential to greatly improve disease symptoms and prevent disease progression in RA patients, they are associated with considerable side-effects and high financial costs. This review summarizes our current understanding of the underlying pathomechanism, diagnosis of RA, as well as the mode of action, clinical benefits, and side-effects of the currently available DMARDs.

pathfindR: An R Package for Comprehensive Identification of Enriched Pathways in Omics Data Through Active Subnetworks

Pathway analysis is often the first choice for studying the mechanisms underlying a phenotype. However, conventional methods for pathway analysis do not take into account complex protein-protein interaction information, resulting in incomplete conclusions. Previously, numerous approaches that utilize protein-protein interaction information to enhance pathway analysis yielded superior results compared to conventional methods. Hereby, we present pathfindR, another approach exploiting protein-protein interaction information and the first R package for active-subnetwork-oriented pathway enrichment analyses for class comparison omics experiments. Using the list of genes obtained from an omics experiment comparing two groups of samples, pathfindR identifies active subnetworks in a protein-protein interaction network. It then performs pathway enrichment analyses on these identified subnetworks. To further reduce the complexity, it provides functionality for clustering the resulting pathways. Moreover, through a scoring function, the overall activity of each pathway in each sample can be estimated. We illustrate the capabilities of our pathway analysis method on three gene expression datasets and compare our results with those obtained from three popular pathway analysis tools. The results demonstrate that literature-supported disease-related pathways ranked higher in our approach compared to the others. Moreover, pathfindR identified additional pathways relevant to the conditions that were not identified by other tools, including pathways named after the conditions.

TNF-β +252 A>G (rs909253) polymorphism is independently associated with presence of autoantibodies in rheumatoid arthritis patients

The TNF-β +252 A>G (rs909253) polymorphism has been associated with a risk of development of rheumatoid arthritis (RA) and could influence plasma tumor necrosis factor alpha (TNF-α) levels. The aim of the present study was to evaluate the association between the TNF-β +252 A>G polymorphism with plasma TNF-α levels, the presence of autoantibodies, and the susceptibility for RA. This cross-sectional study included 261 patients with RA and 292 controls. The polymorphism was studied using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Soluble TNF-α and receptors swere measured by multiplex assay. Rheumatoid factor (RF) and anticyclic citrullinated peptide antibodies (anti-CCP) were measured using immunoassay. No differences were observed in allele frequency and genotype distribution among patients and controls. The presence of RF (p = 0.020) and anti-CCP (p = 0.001) increased 4.23-fold and 8.13-fold, respectively, in patients with B1 allele (B1/B2 + B1/B1 genotypes) independently of demographic, clinical, and inflammatory markers. Among patients with B1/B2 + B1/B1 genotypes, higher TNF-α levels were associated with positive RF (p = 0.040), anti-CCP (p = 0.011), or both (p = 0.038). In patients carrying B1 allele, the increased sTNFR1 together with RF or anti-CCP or both explained about 39.0% the variations in TNF-α level. However, in B2/B2 genotype, the presence of those autoantibodies was not associated with TNF-α level. Our findings indicate that the TNF-β +252 A>G polymorphism was not associated with RA susceptibility and TNF-α plasma levels. However, B1 allele was associated with the presence of autoantibodies. In addition, interaction between the presence of B1 allele and autoantibodies was associated with the increase of plasma TNF-α level in RA patients.

Salmonella Infection in Chronic Inflammation and Gastrointestinal Cancer

Salmonella not only causes acute infections, but can also cause patients to become chronic "asymptomatic" carriers. Salmonella has been verified as a pathogenic factor that contributes to chronic inflammation and carcinogenesis. This review summarizes the acute and chronic Salmonella infection and describes the current research progress of Salmonella infection contributing to inflammatory bowel disease and cancer. Furthermore, this review explores the underlying biological mechanism of the host signaling pathways manipulated by Salmonella effector molecules. Using experimental animal models, researchers have shown that Salmonella infection is related to host biological processes, such as host cell transformation, stem cell maintenance, and changes of the gut microbiota (dysbiosis). Finally, this review discusses the current challenges and future directions in studying Salmonella infection and its association with human diseases.

'RA and the microbiome: do host genetic factors provide the link?

Rheumatoid arthritis (RA) is a chronic autoimmune disease, characterised by painful synovium inflammation, bony erosions, immune activation and the circulation of autoantibodies. Despite recent advances in therapeutics enabling disease suppression, there is a considerable demand for alternative therapeutic strategies as well as optimising those available at present. The relatively low concordance rate between monozygotic twins, 20–30% contrasts with heritability estimates of ∼65%, indicating a substantive role of other risk factors in RA pathogenesis. There is established evidence that RA has an infective component to its aetiology. More recently, differences in the commensal microbiota in RA compared to controls have been identified. Studies have shown that the gut, oral and lung microbiota is different in new onset treatment naïve, and established RA patients, compared to controls. Key taxonomic associations are an increase in abundance of Porphyromonas gingivalis and Prevotella copri in RA patients, compared to healthy controls. Host genetics may provide the link between disease and the microbiome. Genetic influence may be mediated by the host immune system; a differential response to RA associated taxa is suggested. The gut microbiome contains elements which are as much as 30% heritable. A better understanding of the influence of host genetics will shed light onto the role of the microbiome in RA. Here we review the role of the microbiome in RA through the lens of host genetics, and consider future research areas addressing microbiome study design and bioinformatics approaches.

•

Rheumatoid arthritis (RA) affects 1% of the population and is highly debilitating.

•

RA is ~65% heritable, yet the concordance rate between monozygotic twins is just 20–30%, indicating a substantive role of other risk factors.

•

Studies have shown that the gut, oral and lung microbiome is different in treatment naïve and established RA patients, compared to controls.

•

Current findings suggest an important influence of host genetics on the microbiome, which may contribute to RA via the host immune system.

•

Associations of the microbiome with RA described thus far are confounded by host genetics, and future studies need to take account of this.

Anti-inflammatory Activity of MTL-CEBPA, a Small Activating RNA Drug, in LPS-Stimulated Monocytes and Humanized Mice

Excessive or inappropriate inflammatory responses can cause serious and even fatal diseases. The CCAAT/enhancer-binding protein alpha (CEBPA) gene encodes C/EBPα, a transcription factor that plays a fundamental role in controlling maturation of the myeloid lineage and is also expressed during the late phase of inflammatory responses when signs of inflammation are decreasing. MTL-CEBPA, a small activating RNA targeting for upregulation of C/EBPα, is currently being evaluated in a phase 1b trial for treatment of hepatocellular carcinoma. After dosing, subjects had reduced levels of pro-inflammatory cytokines, and we therefore hypothesized that MTL-CEBPA has anti-inflammatory potential. The current study was conducted to determine the effects of C/EBPα saRNA - CEBPA-51 - on inflammation in vitro and in vivo after endotoxin challenge. CEBPA-51 led to increased expression of the C/EBPα gene and inhibition of pro-inflammatory cytokines in THP-1 monocytes previously stimulated by E. coli-derived lipopolysaccharide (LPS). Treatment with MTL-CEBPA in an LPS-challenged humanized mouse model upregulated C/EBPα mRNA, increased neutrophils, and attenuated production of several key pro-inflammatory cytokines, including TNF-α, IL-6, IL-1β, and IFN-γ. In addition, a Luminex analysis of mouse serum revealed that MTL-CEBPA reduced pro-inflammatory cytokines and increased the anti-inflammatory cytokine IL-10. Collectively, the data support further investigation of MTL-CEBPA in acute and chronic inflammatory diseases where this mechanism has pathogenic importance.

Increased risk of rheumatoid arthritis among patients with Mycoplasma pneumonia: A nationwide population-based cohort study in Taiwan

Objective

An association between Mycoplasma pneumonia (MP) and rheumatoid arthritis (RA) had been reported in animal studies for decades. However, clinical evidence for this association is lacking. Therefore, this study aimed to provide epidemiologic evidence to clarify the relationship between MP and development of RA.

Methods

This 13-year nationwide, population-based, retrospective cohort study analyzed the risk of RA in a cohort of MP patients. We cross linked and compared the database of those with catastrophic illnesses to make sure the diagnoses of RA are correctly labeled. We selected 116,053 hospitalized patients diagnosed with MP between 2000 and 2012 from the Taiwan National Health Insurance Research Database and 464,212 matched controls at a 1:4 ratio by age, gender, and index year, in relation to the risk of developing RA. The follow-up period referred to the initial diagnosis of MP until the date of RA diagnosis, censoring of RA, or 31^st December 2013. The Cox proportional hazard model was used to analyze the association between MP and incidence of RA among patients with different potential risks.

Results

The adjusted hazard ratio (HR) for incidental RA in the MP group was 1.37 (95% confidence interval CI = 0.87–2.16), compared to non-MP controls. Stratified analysis revealed that the adjusted HR was 3.05 (95% CI = 1.16–7.99, p = 0.02) in a subgroup of patients over the age of 65.The adjusted HR of RA for the MP group among aged ≦19 years and ≥ 65 years was 3.19 (95% CI = 1.04.9.76) and 4.14 (95% CI = 1.27,13.4) within the first 2 years of follow-up.

Conclusion

This cohort study demonstrated that patients with MP had a higher risk of developing RA, especially in the first 2 years, in those aged younger than 19 and over 65.

Rheumatoid arthritis and the mucosal origins hypothesis: protection turns to destruction

Individuals at high risk of developing seropositive rheumatoid arthritis (RA) can be identified for translational research and disease prevention studies through the presence of highly informative and predictive patterns of RA-related autoantibodies, especially anti-citrullinated protein antibodies (ACPAs), in the serum. In serologically positive individuals without arthritis, designated ACPA positive at risk, the presence of mucosal inflammatory processes associated with the presence of local ACPA production has been demonstrated. In other at-risk populations, local RA-related autoantibody production is present even in the absence of serum autoantibodies. Additionally, a proportion of at-risk individuals exhibit local mucosal ACPA production in the lung, as well as radiographic small-airway disease, sputum hypercellularity and increased neutrophil extracellular trap formation. Other mucosal sites in at-risk individuals also exhibit autoantibody production, inflammation and/or evidence of dysbiosis. As the proportion of individuals who exhibit such localized inflammation-associated ACPA production is substantially higher than the likelihood of an individual developing future RA, this finding raises the hypothesis that mucosal ACPAs have biologically relevant protective roles. Identifying the mechanisms that drive both the generation and loss of externally focused mucosal ACPA production and promote systemic autoantibody expression and ultimately arthritis development should provide insights into new therapeutic approaches to prevent RA.

Interactions of antisera to different Chlamydia and Chlamydophila species with the ribosomal protein RPS27a correlate with impaired protein synthesis in a human choroid plexus papilloma cell line

Chlamydia trachomatis (CT) and the Chlamydophila species (CS) Chlamydophila pneumoniae (CPn), and Chlamydophila psittaci (CPs) are suggested to induce autoantibodies causative of several human autoimmune disorders like rheumatoid arthritis and systemic lupus erythematosus (SLE). The aim of the present study was therefore to identify cellular protein interaction partners with antisera to CT (α-CT) or CS (α-CS) and to identify functional consequences of such interaction in vitro. As detected with a commercial first trimester human prenatal brain multiprotein array (hEXselect, Engine, Germany), the most frequent interaction partner with both α-CT and α-CS was the ribosomal small subunit protein RPS27a. This could be confirmed by Western blot analysis with a recombinant RPS27a sample. In addition, immunocytochemistry with both antisera in the human choroid plexus papilloma cell line HIBCPP revealed a granular cytoplasmic staining, and Western blot analysis with whole-cell protein samples of HIBCPP cells revealed both antisera to label protein bands of different molecular weights and intensity. By 2D Western blot analysis and mass spectrometry, one of the protein spots interacting with α-CT could be identified as the RPS27a. Finally, two different methods for the detection of protein synthesis activity, the SUnSET technique and an HPG fluorescence assay revealed both antisera to cause reduced translational activity in HIBCPP cells. Together with previous findings of RPS27a as an autoimmune target in a mouse model of systemic lupus erythematosus (SLE), these results suggest that infections with CT and/or CS could induce SLE-associated immune modifications. However, direct evidence for a pathogenic role of these interactions for SLE demands further investigations.

Toxoplasmosis seroprevalence in rheumatoid arthritis patients: A systematic review and meta-analysis

BACKGROUND

Toxoplasmosis is a cosmopolitan infection caused by an intracellular obligatory protozoan, Toxoplasma gondii. Infection to this parasite in immunocompetent patients is usually asymptomatic, but today it is believed that the infection can be a risk factor for a variety of diseases, including rheumatoid arthritis (RA). RA is an autoimmune disease and the most common type of inflammatory arthritis that is a major cause of disability. The aim of this systematic review and meta-analysis was to address the association between RA and toxoplasmosis in light of the available research.

METHODS

Based on the keywords, a systematic search of eight databases was conducted to retrieve the relevant English-language articles. Then, the studies were screened based on the inclusion and exclusion criteria. The random effect model was used to calculate the odds ratio (OR) using forest plot with 95% confidence interval (CI).

RESULTS

Overall, 4168 Individual, extracted from 9 articles were included for systematic review evaluation, with 1369 RA patients (46% positive toxoplasmosis) and 2799 individuals as controls (21% positive toxoplasmosis). Then, eight articles (10 datasets) were used for meta-analysis (1244 rheumatoid arthritis patients and 2799 controls). By random effect model, the combined OR was 3.30 (95% CI: 2.05 to 5.30) with P < 0.0001.

CONCLUSION

Although toxoplasmosis could be considered as a potential risk factor for rheumatoid arthritis, more and better quality studies are needed to determine the effect of T. gondii infection on induction or exacerbation of RA. Our study was registered at the International Prospective Register of Systematic Reviews (PROSPERO; code: CRD42017069384).

PhosphoLipid transfer protein (PLTP) exerts a direct pro-inflammatory effect on rheumatoid arthritis (RA) fibroblasts-like-synoviocytes (FLS) independently of its lipid transfer activity

Rheumatoid arthritis (RA) is a chronic inflammatory rheumatic disease with modification of lipids profile and an increased risk of cardiovascular events related to inflammation. Plasma phospholipid transfer protein (PLTP) exerts a lipid transfer activity through its active form. PLTP can also bind to receptors such as ATP-binding cassette transporter A1 (ABCA1). In addition to its role in lipoprotein metabolism and atherosclerosis, the latest advances came in support of a complex role of PLTP in the regulation of the inflammatory response, both with pro-inflammatory or anti-inflammatory properties. The aim of the present study was to decipher the role of PLTP in joint inflammation and to assess its relevance in the context of RA. PLTP expression was examined by western-blot and by immunochemistry. ABCA1 expression was analyzed by flow cytometry. Lipid transfer activity of PLTP and pro-inflammatory cytokines were measured in sera and synovial fluid (SF) from RA patients and controls (healthy subjects or osteoarthritis patients [OA]). FLS were treated with both lipid-transfer active form and inactive form of recombinant human PLTP. IL-8, IL-6, VEGF and MMP3 produced by FLS were assessed by ELISA, and proliferation by measuring ³H-Thymidine incorporation. RA synovial tissues showed higher PLTP staining than OA and PLTP protein levels were also significantly higher in RA-FLS. In addition, RA, unlike OA patients, displayed elevated levels of PLTP activity in SF, which correlated with pro-inflammatory cytokines. Both lipid-transfer active and inactive forms of PLTP significantly increased the production of cytokines and proliferation of FLS. ABCA1 was expressed on RAFLS and PLTP activated STAT3 pathway. To conclude, PLTP is highly expressed in the joints of RA patients and may directly trigger inflammation and FLS proliferation, independently of its lipid transfer activity. These results suggest a pro-inflammatory role for PLTP in RA.

The Complex Interplay between Chronic Inflammation, the Microbiome, and Cancer: Understanding Disease Progression and What We Can Do to Prevent It

Cancer is a multifaceted condition, in which a senescent cell begins dividing in an irregular manner due to various factors such as DNA damage, growth factors and inflammation. Inflammation is not typically discussed as carcinogenic; however, a significant percentage of cancers arise from chronic microbial infections and damage brought on by chronic inflammation. A hallmark cancer-inducing microbe is Helicobacter pylori and its causation of peptic ulcers and potentially gastric cancer. This review discusses the recent developments in understanding microbes in health and disease and their potential role in the progression of cancer. To date, microbes can be linked to almost every cancer, including colon, pancreatic, gastric, and even prostate. We discuss the known mechanisms by which these microbes can induce cancer growth and development and how inflammatory cells may contribute to cancer progression. We also discuss new treatments that target the chronic inflammatory conditions and their associated cancers, and the impact microbes have on treatment success. Finally, we examine common dietary misconceptions in relation to microbes and cancer and how to avoid getting caught up in the misinterpretation and over inflation of the results.

Detection of Shigella spp. nucleic acids in the synovial tissue of Tunisian rheumatoid arthritis patients and other forms of arthritis by quantitative real-time polymerase chain reaction

Enterobacterial components in the joints of patients are believed to contribute to a perpetuating inflammation leading to a reactive arthritis (ReA), a condition in which microbial agents cannot be recovered from the joint. At present, it is unclear whether nucleic acids from Shigella spp. are playing a pathogenic role in causing not only ReA but also other forms of arthritis. Quantitative real-time polymerase chain reaction assay (qPCR) is the method of choice for the identification of bacteria within the synovium. The aim of our study was to detect the presence of Shigella spp. nucleic acids in the synovial tissue (ST) of Tunisian arthritis patients. We investigated 57 ST samples from rheumatoid arthritis (RA) n = 38, undifferentiated oligoarthritis (UOA) n = 12, and spondyloarthritis (SpA) n = 7 patients; 5 ST samples from healthy individuals were used as controls. Shigella spp. DNA and mRNA transcripts encoding the virulence gene A (VirA) were examined using an optimized qPCR with newly designed primers and probes. Using qPCR, Shigella spp. DNA was found in 37/57 (65%) ST samples (24/38, i.e., 63.2% of RA, 8/12, i.e., 67% of UOA, and 5/7, i.e., 71.4% of SpA patients). Paired DNA and mRNA were extracted from 39 ST samples, whose VirA cDNA was found in 29/39 (74.4%) patients. qPCR did not yield any nucleic acids in the five healthy control ST samples. The qPCR assay was sensitive and showed a good intra- and inter-run reproducibility. These preliminary findings generated by an optimized, highly sensitive PCR assay underline a potential role of past gastrointestinal infections. In Tunisian patients, a bacterial etiology involving Shigella spp. in the manifestation of arthritic disorders including RA might be more common than expected.

Direct recognition of LPS drive TLR4 expressing CD8+ T cell activation in patients with rheumatoid arthritis

Aberrant immune responses characterize autoimmune disorders like Rheumatoid Arthritis (RA) wherein lymphocytes are recognized as key players. Role of CD8⁺ T cells in RA has been less defined however we found that these cells are activated in RA patients with increased expression of cytolytic granules and inflammatory mediators thereby modulating immune responses contributing to disease severity. Though unconventional expression of different Toll Like Receptors (TLRs) on CD8⁺ T cells has been proposed but their expression and role in T cell activation and differentiation in RA still remains obscure. Herein we report, for the first time, an increased expression of TLR4 on peripheral CD8⁺ T cells of RA patients and its role in skewing CD8⁺ T cells towards activated and inflammatory phenotype thereby playing a significant role in pathogenesis and progression of RA. We found that the surface expression of TLR4 on CD8⁺ T cells directly correlates with disease severity. Moreover, these CD8⁺ T cells respond to the TLR4 ligand LPS and express robust amounts of cytotolytic and inflammatory molecules including TNFα and IFNγ. Our study hence identifies an important role for CD8⁺ T cells in orchestrating RA through TLR4 mediated activation and differentiation.