Vasculitis reumatoidea: una manifestación poco habitual. Presentación de tres casos clínicos y revisión de la literatura

La vasculitis reumatoidea es una complicación sistémica y poco frecuente de la Artritis Reumatoidea. Si bien su incidencia ha descendido en los últimos años con el advenimiento de las nuevas terapias inmunosupresoras y biológicas, continua teniendo una alta morbimortalidad. Predomina en el sexo masculino, en pacientes seropositivos y con un largo período de la enfermedad establecida. Requiere de alta presunción diagnostica, siendo el compromiso cutáneo y nervioso periférico el más frecuente. La biopsia de nervio o piel es requerida habitualmente para su diagnóstico. El tratamiento se basa en corticoides e inmunosupresores. Presentamos tres casos clínicos y realizamos una revisión de la literatura.

Rheumatoid vasculitis is a rare systemic complication of rheumatoid arthritis. Although its incidence has decreased in recent years with the advent of new immunosuppressive and biological therapies, it continues to have a high morbidity and mortality. It predominates in males, in seropositive patients and with a long period of established disease. It requires high diagnostic presumption, with skin and peripheral nervous involvement being the most affected. Nerve or skin biopsy is usually required for diagnosis. Treatment is based on corticosteroids and immunosuppressants. We present three clinical cases and carry out a review of the literature.

A vasculite reumatóide é uma complicação sistêmica rara da artrite reumatóide. Embora sua incidência tenha diminuído nos últimos anos com o advento de novas terapias imunossupressoras e biológicas, continua apresentando elevada morbidade e mortalidade. Predomina no sexo masculino, em pacientes soropositivos e com longo período de doença estabelecida. Exige alta presunção diagnóstica, sendo o envolvimento cutâneo e nervoso periférico os mais afetados. A biópsia de nervo ou pele geralmente é necessária para o diagnóstico. O tratamento é baseado em corticosteroides e imunossupressores. Apresentamos três casos clínicos e realizamos uma revisão da literatura.

Rheumatoid arthritis reduces the risk of colorectal cancer through immune inflammation mediation.

There is a close relationship between immune-mediated inflammation and cancer, and there is still controversy over whether rheumatoid arthritis (RA) increases the risk of malignancy. We first used Mendelian randomization (MR) analysis to explore the potential causal relationship between RA and pan-cancer. And verify the effect of immune-mediated inflammation on cancer through intermediate MR analysis. Then we extracted the standardized incidence rate of malignancy in RA patients relative to the general population through large-scale meta-analysis. Finally, we performed pan-cancer analysis on the RA related genes obtained from MR analysis. And perform immune related analysis on key genes to reveal the association between RA and malignancy. The MR analysis demonstrated a negative correlation between RA and pan-cancer (p = 0.008). Autoimmune traits were the main mediating variable for the causal relationship between RA and pan-cancer. Based on the results of the meta-analysis, we validated that RA reduces the risk of developing colorectal cancer (SIR = 0.69, 95% CI 0.53-0.85). Pan-cancer analysis also showed that high expression of RA related genes was negatively correlated with colon adenocarcinoma. IL6R was the gene with the highest correlation among them, and its correlation with immune cells was higher in colorectal cancer than in other malignancy. Our MR study provides evidence that RA was associated with reduced risk of colorectal cancer. This effect is caused by immune-mediated inflammation, with IL6R being a key regulatory gene.

Management of refractory disease and persistent symptoms in inflammatory arthritis: qualitative framework analysis of interviews with patients and healthcare professionals.

Objectives: This study aims to explore patients' and clinicians' experiences in managing and living with refractory disease (RD) and persistent physical and emotional symptoms (PPES) in patients with RA or polyarticular JIA from their perspectives through interviews and/or focus groups. Methods: A qualitative exploration with 25 patients and 32 multidisciplinary rheumatology healthcare professionals (HCPs) was conducted to obtain participants respective understanding and experiences of managing RD/PPES and its impact on the patient-professional relationship. A pragmatic epistemology approach with framework analysis was employed. Results: Four key themes were identified from both patients and professionals in the management of RD/PPES: risk/perpetuating factors/triggers; need for a patient-centred holistic approach to care, diagnosis and treatment; discordance and impact on the patient-practitioner relationship and current problems in managing RD/PPES. These themes covered 22 subthemes, with none being patient specific and seven being HCP specific. Suggestions for potential management strategies were highlighted throughout, such as involving other specialties or a multidisciplinary team, assessing/treating patient-reported outcome measures and psychosocial factors, patient (re)education, need for adjustments/aids or adaptations, checking the diagnosis and further investigations/imaging and optimizing medications. Conclusion: Management strategies need to be developed that enable appropriate treatment plans for those with RD/PPES that account for wider biopsychosocial factors beyond inflammation and reduce discordance in the patient-practitioner relationship.

A Distinct Instance of Palindromic Rheumatism Disguised as Polymyalgia Rheumatica.

In this case report, we highlight a rare case of palindromic rheumatism (PR) presenting as polymyalgia rheumatica (PMR). Many challenges and complexities are associated with diagnosing and treating PR. Literature reviews showed only a few case reports of this unique presentation. PR has a distinct presentation that often goes unnoticed and is misinterpreted by medical professionals. A more thorough clinical approach is required to identify and treat this condition. We hope sharing such uncommon cases will help the medical community better understand PR and develop improved diagnostic and therapeutic options. This case also demonstrates the need for further research to better understand the pathogenesis of this uncommon condition.

The causal relationship between rheumatoid arthritis and bronchiectasis: a bidirectional Mendelian randomization study.

Background: Several observational studies suggested an association between rheumatoid arthritis (RA) and bronchiectasis. Nevertheless, the presence of a causal relationship between these conditions is yet to be determined. This study aimed to investigate whether genetically predicted RA is associated with the risk of bronchiectasis and vice versa. Methods: We obtained RA genome-wide association study (GWAS) data from FinnGen consortium, and bronchiectasis GWAS data from IEU Open GWAS project. Univariate Mendelian randomization (MR) analysis was performed using inverse variance weighted (IVW) estimation as the main method. Furthermore, bidirectional and replication MR analysis, multivariate MR (MVMR), Mediation analysis, and sensitivity analyses were conducted to validate the findings. Results: In the UVMR analysis, the IVW results revealed that RA had an increased risk of bronchiectasis (OR = 1.18, 95% CI = 1.10-1.27; p = 2.34 × 10-6). In the reverse MR analysis, no evidence of a causal effect of bronchiectasis on the risk of RA was detected. Conversely, in the replication MR analysis, RA remained associated with an increased risk of bronchiectasis. Estimates remained consistent in MVMR analyses after adjusting for the prescription of non-steroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids. Immunosuppressants were found to mediate 58% of the effect of the RA on bronchiectasis. Sensitivity analyses confirmed the stability of these associations. Conclusion: This study demonstrated a positive causal relationship between RA and an increased risk of bronchiectasis, offering insights for the early prevention of bronchiectasis in RA patients and shedding new light on the potential role of immunosuppressants as mediators in promoting the effects of RA on bronchiectasis.

Yishen Tongbi decoction attenuates inflammation and bone destruction in rheumatoid arthritis by regulating JAK/STAT3/SOCS3 pathway.

Background: Yishen-Tongbi Decoction (YSTB), a traditional Chinese prescription, has been used to improve syndromes of rheumatoid arthritis (RA) for many years. Previous research has shown that YSTB has anti-inflammatory and analgesic properties. However, the underlying molecular mechanism of the anti-RA effects of YSTB remains unclear. Purpose and study design: The purpose of this research was to investigate how YSTB affected mice with collagen-induced arthritis (CIA) and RAW264.7 cells induced with lipopolysaccharide (LPS). Results: The findings show that YSTB could significantly improve the clinical arthritic symptoms of CIA mice (mitigate paw swelling, arthritis score, thymus and spleen indices, augment body weight), downregulated expression of pro-inflammatory cytokines like tumor necrosis factor-alpha (TNF-α), interleukin-1ß (IL-1ß), IL-6 and IL-17, while upregulated the level of anti-inflammatory like IL-10 and transforming growth factor-ß (TGF-ß). Meanwhile, YSTB inhibits bone erosion and reduces inflammatory cell infiltration, synovial proliferation, and joint destruction in CIA mice. In addition, we found that YSTB was able to suppress the LPS-induced inflammation of RAW264.7 cells, which was ascribed to the suppression of nitric oxide (NO) production and reactive oxygen species formation (ROS). YSTB also inhibited the production of inducible nitric oxide synthase and reduced the releases of pro-inflammatory cytokines TNF-α, IL-1ß, and IL-6 in LPS-induced RAW264.7 cells. Furthermore, the phosphorylation expression of JAK2, JAK3, STAT3, p38, ERK and p65 protein could be suppressed by YSTB, while the expression of SOCS3 could be activated. Conclusion: Taken together, YSTB possesses anti-inflammatory and prevention bone destruction effects in RA disease by regulating the JAK/STAT3/SOCS3 signaling pathway.

Importance of Vaccination Against COVID-19 in a Patient With End-Stage Rheumatoid Arthritis-Associated Interstitial Lung Disease (RA-ILD).

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by inflammatory polyarthritis and extra-articular involvement. Extraarticular manifestations of RA can include involvement of the skin, eye, heart, lungs, and others. RA is associated with a broad spectrum of pleuropulmonary involvement, with interstitial lung disease (ILD) and pleural disease being the most common. COVID-19 infection cross-talks with RA at various stages of pathogenesis. The clinical course and outcome of COVID-19 infection in RA patients may be ameliorated due to various reasons including anti-rheumatic drugs; however, COVID-19 vaccination provides additional protection to high-risk patients compared to non-vaccinated patients. Here, we present a case of end-stage RA-associated ILD who presented with the chief complaint of shortness of breath and tested positive for COVID-19. She was a lung transplant candidate on long-term antifibrotic medication nintedanib for interstitial fibrosis. The patient survived the initial acute hypoxemic respiratory failure, which might be attributed to being fully vaccinated for COVID-19.

Characterization of the MicroRNA profile in rheumatoid arthritis plasma exosomes and their roles in B-cell responses.

OBJECTIVE: This study aimed to identify differentially expressed microRNAs (miRNAs) in exosomes derived from the blood plasma of Rheumatoid Arthritis (RA) patients and explore their clinical significance and biological roles. METHODS: Illumina high-throughput sequencing was employed to measure miRNA expression levels in plasma exosomes, followed by validation using qRT-PCR. The correlation between exosomal miRNAs and disease activity was systematically analyzed. Additionally, the pathogenic effects of RA exosomes were investigated through bioinformatics analysis and in vitro experiments. RESULTS: Significantly reduced levels of exosomal miR-144-3p and miR-30b-5p were observed in RA patients, which were negatively correlated with DAS28 scores and anti-CCP antibody levels. ROC curve analysis showed that miR-144-3p and miR-30b-5p in plasma exosomes could effectively distinguish RA patients from healthy controls, with AUC values of 0.725 and 0.773, respectively. Combining bioinformatics analysis and in vitro experiments, it was demonstrated that plasma exosomes contribute to ongoing autoantibody production in RA by promoting B-cell differentiation and antibody production. CONCLUSION: The present study indicates that plasma exosomes from RA patients may be potentially pathogenic. Exosomal miR-144-3p and miR-30b-5p exhibit significant decreases in RA patients and are associated with disease activity, suggesting their potential as valuable biomarkers for RA.

A Case of Painless Elderly-Onset Rheumatoid Arthritis.

Rheumatoid arthritis (RA) has multiple manifestations. Patients present with a variety of symptoms and varying levels of severity. Elderly-onset rheumatoid arthritis (EORA) is described as RA with onset after 60 years of age. EORA can present with different clinical and laboratory findings compared to RA in a younger patient, making awareness of the condition important. Diagnosing inflammatory arthritis can be especially challenging in an elderly population where symptoms are poorly reported and communication is often difficult. We report the case of an elderly patient whose presentation with persistent tachycardia and raised inflammatory markers led to a diagnosis of EORA. This case details an atypical presentation of EORA with convincing diagnostic features for the disease without any joint symptoms reported. Clinicians should be aware of the differences in the typical presentation of EORA versus RA, the challenges of diagnosing inflammatory arthritis in elderly, isolated patients, and the importance of early diagnosis.

Xiaowugui decoction alleviates experimental rheumatoid arthritis by suppressing Rab5a-mediated TLR4 internalization in macrophages.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by exacerbated synovial inflammation and joint destruction. Recent studies suggest toll-like receptor 4 (TLR4) internalization facilitate inflammatory response of macrophage. The role of TLR4 internalization in the pathogenesis of RA is unknown. PURPOSE: To investigate the role and mechanism of TLR4 internalization in macrophage inflammatory response of RA and explore whether TLR4 internalization mediates the anti-arthritic effect of Xiaowugui (XWG) decoction, a patented herbal formula used in China. METHODS: The co-expression of TLR4 and the internalization marker, early endosome antigen 1 (EEA1), in the synovial samples of RA patients and joint tissue of collagen-induced arthritis (CIA) mice, were evaluated using immunofluorescence. The effect of Rab5a-mediated early internalization of TLR4 on the activation induced by lipopolysaccharide (LPS) in RAW264.7 cells was investigated using small interfering RNAs that act against Rab5a. CIA was induced in Rab5a-/- mice to evaluate the role of Rab5a in vivo. The disease progression and expression of Rab5a and TLR4 in the joint tissue were evaluated in CIA mice treated with XWG. Inflammatory factors production, TLR4 internalization, and activation of downstream signaling pathways were examined in RAW264.7 cells treated with XWG in vitro. RESULTS: The co-expression and co-localization of TLR4 and EEA1 were elevated in the synovial samples of RA patients and joint tissue of CIA mice. Pharmaceutical inhibition of TLR4 internalization reduced macrophages inflammatory responses induced by LPS. The co-expression and co-localization of Rab5a and TLR4 were significantly increased in macrophages treated with LPS. Silencing Rab5a reduced LPS-induced TLR4 internalization, inflammatory factors production, and phosphorylation of Jun N-terminal kinases (JNK) and p65. Genetic deletion of Rab5a inhibited TLR4 internalization and the development of arthritis in vivo. The co-expression of TLR4 and Rab5a was also elevated in the synovial samples of RA patients. XWG treatment of mice with CIA alleviated arthritis and reduced the co-expression of Rab5a and TLR4 in the joint tissue. XWG treatment of macrophage inhibited LPS-induced IL-6 and TNF-α production, co-expression of Rab5a and TLR4, and phosphorylation of JNK and p65. CONCLUSIONS: Our findings highlight the pathogenic role of TLR4 internalization in patients with RA and identify a novel Rab5a-dependent internalization pathway that promotes macrophage inflammatory response. XWG treatment demonstrated outstanding therapeutic effects in experimental arthritis, and targeting the Rab5a-mediated internalization of TLR4 may be the main underlying mechanism.

Acod1-mediated inhibition of aerobic glycolysis suppresses osteoclast differentiation and attenuates bone erosion in arthritis.

OBJECTIVES: Metabolic changes are crucially involved in osteoclast development and may contribute to bone degradation in rheumatoid arthritis (RA). The enzyme aconitate decarboxylase 1 (Acod1) is known to link the cellular function of monocyte-derived macrophages to their metabolic status. As osteoclasts derive from the monocyte lineage, we hypothesised a role for Acod1 and its metabolite itaconate in osteoclast differentiation and arthritis-associated bone loss. METHODS: Itaconate levels were measured in human peripheral blood mononuclear cells (PBMCs) of patients with RA and healthy controls by mass spectrometry. Human and murine osteoclasts were treated with the itaconate derivative 4-octyl-itaconate (4-OI) in vitro. We examined the impact of Acod1-deficiency and 4-OI treatment on bone erosion in mice using K/BxN serum-induced arthritis and human TNF transgenic (hTNFtg) mice. SCENITH and extracellular flux analyses were used to evaluate the metabolic activity of osteoclasts and osteoclast progenitors. Acod1-dependent and itaconate-dependent changes in the osteoclast transcriptome were identified by RNA sequencing. CRISPR/Cas9 gene editing was used to investigate the role of hypoxia-inducible factor (Hif)-1α in Acod1-mediated regulation of osteoclast development. RESULTS: Itaconate levels in PBMCs from patients with RA were inversely correlated with disease activity. Acod1-deficient mice exhibited increased osteoclast numbers and bone erosion in experimental arthritis while 4-OI treatment alleviated inflammatory bone loss in vivo and inhibited human and murine osteoclast differentiation in vitro. Mechanistically, Acod1 suppressed osteoclast differentiation by inhibiting succinate dehydrogenase-dependent production of reactive oxygen species and Hif1α-mediated induction of aerobic glycolysis. CONCLUSION: Acod1 and itaconate are crucial regulators of osteoclast differentiation and bone loss in inflammatory arthritis.

Efficacy and safety of first-line biological DMARDs in rheumatoid arthritis patients with chronic kidney disease.

OBJECTIVE: To evaluate the efficacy and safety of first-line biological disease-modifying antirheumatic drugs (bDMARDs) in patients with rheumatoid arthritis (RA) with chronic kidney disease (CKD), including those undergoing haemodialysis (HD). METHODS: This retrospective cohort study included 425 patients with RA prescribed their first bDMARDs at two hospitals from 2004 to 2021. Patients were categorised by kidney function and bDMARD modality (TNFα inhibitors (TNFαis), interleukin-6 inhibitors (IL-6is), cytotoxic T-lymphocyte antigen-4 immunoglobulin (CTLA4-Ig)). The primary outcome was the 36-month drug retention rate, with secondary outcomes including changes in Disease Activity Score 28 (DAS28)-C reactive protein (CRP)/erythrocyte sedimentation rate (ESR), prednisolone dosage and reasons for discontinuation. RESULTS: The 36-month drug retention rates by estimated glomerular filtration rate (eGFR) (≥60, 30-60, <30 mL/min/1.73 m2) were as follows: all bDMARDs (45.2%, 32.0%, 41.4%), TNFαis (45.3%, 28.2%, 34.0%), IL-6is (47.4%, 66.7%, 71.4%) and CTLA-4Ig (50.0%, 31.3%, 33.3%). Even in groups with lower kidney function, the drug retention rate of bDMARDs was generally maintained. However, the retention rate of TNFαis was significantly lower in patients with eGFR <30 mL/min/1.73 m2. IL-6is showed the highest retention rate and the lowest discontinuation rate due to ineffectiveness in this group (HR 0.11, 95% CI 0.02 to 0.85, p=0.03). All bDMARDs improved DAS28-CRP/ESR and reduced prednisolone dosage across all groups. CONCLUSION: bDMARDs demonstrated effective and safe profiles in patients with RA with CKD, even among patients on HD. In particular, IL-6is had a significantly higher drug retention rate in patients with an eGFR of <30 mL/min/1.73 m2 and fewer discontinuations due to ineffectiveness. IL-6is were more efficacious as monotherapy compared with the other bDMARDs.

Comparison of disease-modifying anti-rheumatic drugs and hyperbaric oxygen therapy in the experimental model of rheumatoid arthritis in rats.

In this study, we wanted to investigate the effectiveness of combining disease-modifying anti-rheumatic drugs (DMARD) with hyperbaric oxygen therapy (HBOT) in reducing inflammation in a rheumatoid arthritis (RA) model using rats. We divided 56 male Sprague-Dawley rats into seven groups and induced RA using complete Freund's adjuvant. Some groups received HBOT, whereas others were given etanercept or leflunomide. We started the treatment on the 10th day after inducing RA and continued it for 18 days. To evaluate the effectiveness of the treatments, we measured paw swelling and used X-rays to examine the joints before and after the treatment. We also analysed the levels of two inflammatory markers, tumour necrosis factor (TNF)-α and interleukin (IL)-1ß, using an enzyme-linked immunosorbent assay. Additionally, we conducted histological analysis and assessed the expressions of anti-IL-1ß and anti-TNF-α antibodies. All the treatment groups showed a significant decrease in arthritis scores, paw swelling and levels of TNF-α and IL-1ß. The X-ray images revealed improvements in joint structure, and the histopathological analysis showed reduced inflammation and collagen abnormalities. Combining DMARD with HBOT had similar effects to individual therapies, suggesting a cost-effective and potentially safer approach for improving outcomes in rats with RA.

Pharmacokinetic-pharmacodynamic modelling and simulation of methotrexate dosing in patients with rheumatoid arthritis.

AIMS: To develop a non-linear mixed-effects population pharmacokinetic and pharmacodynamic (PK-PD) model describing the change in the concentration of methotrexate polyglutamates in erythrocytes (ery-MTX-PGn with "n" number of glutamate, representing PK component) and how this relates to modified 28-joint Disease Activity Score incorporating erythrocyte sedimentation rate (DAS-28-3) for rheumatoid arthritis (RA), representing PD component. METHODS: An existing PK model was fitted to data from a study consisting of 117 RA patients. The estimation of population PK-PD parameters was performed using stochastic approximation expectation maximisation algorithm in Monolix 2021R2. The model was used to perform Monte Carlo simulations of a loading dose regimen (50mg subcutaneous methotrexate as loading doses, then 20mg weekly oral methotrexate) compared to a standard dosing regimen (10mg weekly oral methotrexate for 2 weeks, then 20mg weekly oral methotrexate). RESULTS: Every 40 nmol/L increase in ery-MTX-PG3-5 total concentration correlated with 1-unit reduction in DAS-28-3. Significant covariate effects on the therapeutic response of methotrexate included the use of prednisolone in the first 4 weeks (positive use correlated with 25% reduction in DAS-28-3 when other variables were constant) and patient age (every 10-year increase in age correlated with 3.4% increase in DAS-28-3 when other variables were constant). 4 methotrexate loading doses led to a higher percentage of patients achieving a good/moderate response compared to the standard regimen (Week 4: 87.6% vs. 39.8%; Week 10: 64.7% vs. 57.0%). CONCLUSIONS: A loading dose regimen was more likely to achieve higher ery-MTX-PG concentration and better therapeutic response after 4 weeks of methotrexate treatment.

Rheumatoid arthritis extra-articular lung disease: new insights on pathogenesis and experimental drugs.

INTRODUCTION: Pulmonary involvement is one of the most common extra-articular manifestations of rheumatoid arthritis (RA), a systemic inflammatory disease characterized by joint swelling and tenderness. All lung compartments can be interested in the course of RA, including parenchyma, airways, and, more rarely, pleura and vasculature. AREAS COVERED: The aim of this paper is to review the main RA lung manifestations, focusing on pathogenesis, clinical and therapeutic issues of RA-related interstitial lung disease (ILD). Despite an increasing number of studies in the last years, pathogenesis of RA-ILD remains largely debated and the treatment of RA patients with lung involvement is still challenging in these patients. EXPERT OPINION: Management of RA-ILD is largely based on expert-opinion. Due to the broad clinical manifestations, including both joints and pulmonary involvement, multidisciplinary discussion, including rheumatologist and pulmonologist, is essential, not only for diagnosis, but also to evaluate the best therapeutic approach and follow-up. In fact, the coexistence of different lung manifestations may influence the treatment response and safety. The identification of biomarkers and risk-factors for an early identification of RA patients at risk of developing ILD remains a need that still needs to be fulfilled, and that will require further investigation in the next years.

Mangiferin: A natural bioactive immunomodulating glucosylxanthone with potential against cancer and rheumatoid arthritis.

Mangiferin is a naturally occurring glucosylxanthone that has shown promising immunomodulatory effects. It is generally isolated from the leaves, peels, bark, and kernels of Mangifera indica Linn. Mangiferin is like a miraculous natural bioactive molecule that has an immunomodulatory function that makes it a potential therapeutic candidate for the treatment of rheumatoid arthritis (RA) and cancer. The anticancer activity of mangiferin acts by blocking NF-κB, as well as regulating the ß-catenin, EMT, MMP9, MMP2, LDH, ROS, and NO, and also by the activation of macrophages. It has no cytotoxic effect on grown chondrocytes and lowers matrix metalloproteinase levels. Additionally, it has a potent proapoptotic impact on synoviocytes. The precise molecular mechanism of action of mangiferin on RA and malignancies is still unknown. This comprehensive review elaborates on the immunomodulatory effect of mangiferin and its anticancer and anti-RA activity. This also explained the total synthesis of mangiferin and its in vitro and in vivo screening models.

Fibroblast-like synoviocytes orchestrate daily rhythmic inflammation in arthritis.

Rheumatoid arthritis is a chronic inflammatory disease that shows characteristic diurnal variation in symptom severity, where joint resident fibroblast-like synoviocytes (FLS) act as important mediators of arthritis pathology. We investigate the role of FLS circadian clock function in directing rhythmic joint inflammation in a murine model of inflammatory arthritis. We demonstrate FLS time-of-day-dependent gene expression is attenuated in arthritic joints, except for a subset of disease-modifying genes. The deletion of essential clock gene Bmal1 in FLS reduced susceptibility to collagen-induced arthritis but did not impact symptomatic severity in affected mice. Notably, FLS Bmal1 deletion resulted in loss of diurnal expression of disease-modulating genes across the joint, and elevated production of MMP3, a prognostic marker of joint damage in inflammatory arthritis. This work identifies the FLS circadian clock as an influential driver of daily oscillations in joint inflammation, and a potential regulator of destructive pathology in chronic inflammatory arthritis.

Methotrexate - Safe Backbone for the Treatment of Rheumatoid Arthritis.

Methotrexate (MTX) is the primarily used disease-modifying antirheumatic drug (DMARD) for the treatment of Rheumatoid Arthritis (RA). MTX is a safe agent, even when used for years - provided that treatment is regularly monitored and prescribers follow some simple rules, such as prescribing tablets of a single strength only. Proper patient education contributes greatly to safe treatment. The knowledge of important pharmacologic facts, possible interactions, and clinical warning signs also helps to prevent or recognize intoxications early. Therefore, this review addresses key aspects regarding the safety of MTX. In this respect, it includes adverse events, possible interactions with frequently used drugs and details on the rare but life-threatening intoxication, e.g., due to erroneous daily intake.