Search Results (86)

The crystal arthropathies gout and calcium pyrophosphate deposition (CPPD) disease represent a significant subset of rheumatic and musculoskeletal diseases, yet their overlap with common entities such as osteoarthritis (OA), rheumatoid arthritis (RA), and psoriatic arthritis (PsA) remains underrecognized. We conducted a structured narrative review of studies published through August 2025, exploring the epidemiology, clinical presentation, imaging characteristics, and treatment implications of these overlapping conditions. We particularly examine how crystal deposition may mimic or complicate the clinical course of OA, RA, and PsA, especially in older adults with multimorbidity. Recognizing these overlaps is critical to avoid misdiagnosis, inappropriate escalation of immunomodulatory therapy, and missed opportunities for targeted crystal-directed treatment. Full article

Rheumatoid arthritis (RA) is an autoimmune disorder characterized by synovial inflammation and progressive joint destruction. There is no cure, and patient responses to current therapies vary, reflecting underlying pathogenic heterogeneity. Leveraging single-cell RNA sequencing (scRNA-seq) of RA synovium, we identified a PLAUR/uPAR-high myeloid subset that co-expresses pathogenic mediators, including IL1B and CXCL8. To target these cells, we developed anti-uPAR antibody–drug conjugates (ADCs) and evaluated various payloads in vitro and in vivo. ADCs bearing BCL-2 family inhibitors selectively induced apoptosis in proinflammatory human monocytes and macrophages with elevated uPAR, while sparing unstimulated monocytes with low basal uPAR in vitro. The treatment also reduced CXCL8 secretion. Given that murine myeloid cells exhibited lower uPAR expression and reduced sensitivity to BCL-2 family inhibitors, we used a monomethyl auristatin F (MMAF) payload to demonstrate in vivo proof-of-concept. In an air-pouch model, the anti-uPAR–MMAF conjugate reduced uPAR^highCD11b⁺F4/80⁺ macrophages by 39% compared with the isotype control. Together, our study underscores the potential of ADCs to eliminate disease-relevant cell types with inducible cell surface markers. This work opens new avenues for exploring cytotoxic ADCs as targeted therapies for autoimmune and inflammatory diseases. Full article

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterised by persistent joint inflammation and systemic immune dysregulation. While bone marrow activation has been linked to RA pathogenesis, direct access to bone marrow tissue for progenitor analysis remains limited by ethical and technical constraints. Analysis of progenitor cells in peripheral blood can serve as a surrogate reflecting bone marrow activation. In this study, we analysed peripheral blood cells from 12 RA patients and 9 healthy controls using high-dimensional spectral flow cytometry with a nine-marker panel (CD45, CD31, CD235, CD133, CD34, CD105, CD271, CD90, PDPN). Flow Self-Organizing Map (FlowSOM) clustering identified 20 distinct cell populations. Additionally, a complementary flow cytometry panel was used to assess CD31 expression on immune subsets in peripheral mononuclear cells (PBMCs) from 9 RA and 9 healthy donors of this cohort. RA patients showed increased CD45⁺CD31⁻ immune cells, but not their putative progenitors. Conversely, putative CD45⁺CD31^int progenitors and CD45⁺CD31^int mature cells were reduced, along with CD31 expression on T cells. Levels of CD235a⁺ putative erythroid precursors and CD45⁺CD31⁺ progenitors were significantly increased in RA patients. Three putative stromal cell populations were detected in circulation. Together, these findings reveal expanded erythroid precursor populations and reduced CD31 expression on T cells in RA. Our data underscore broad systemic alterations in cellular homeostasis in RA patients. In conclusion, our results suggest that the loss of CD31 expression on immune cell precursors plays a role in age-associated immune remodelling and immune activation in RA and provides the rationale for further studies on erythroblast differentiation and the functional role of erythroblasts in chronic inflammation. Full article

Rheumatoid arthritis is a chronic systemic autoimmune disease that arises from complex interactions among genetic susceptibility, environmental factors, and immune dysregulation. Growing evidence indicates that microorganisms residing in the oral cavity and gastrointestinal tract, together with dietary factors, play a central role in shaping inflammatory and autoimmune responses in rheumatoid arthritis, forming an interconnected microbiome–immune–nutrition axis. Alterations in the composition and function of oral and intestinal microbial communities are associated with disruption of mucosal barrier integrity, activation of innate and adaptive immune pathways, increased differentiation of proinflammatory T lymphocyte subsets, and loss of immune tolerance that promotes autoantibody production. In addition, microbially derived metabolites, particularly short-chain fatty acids, provide a mechanistic link between microbial ecology, immune regulation, and bone metabolism. Diet represents a key upstream modulator of this axis. Dietary patterns rich in anti-inflammatory nutrients support microbial diversity and immunoregulatory metabolite production, whereas diets high in processed foods and saturated fats favor proinflammatory microbial profiles. Accumulating clinical evidence suggests that nutritional strategies and microbiome-targeted dietary interventions may reduce systemic inflammation and disease-related comorbidities when used alongside standard pharmacological treatments. Taken together, the microbiome–immune–nutrition axis represents a modifiable and clinically meaningful target in rheumatoid arthritis, emphasizing the need for interdisciplinary research and well-designed clinical trials to translate these insights into personalized approaches for disease management. The aim of this review is to integrate current mechanistic and clinical evidence on the interactions between the microbiome, immune system, and nutrition in rheumatoid arthritis, with a focus on their pathogenic relevance, therapeutic potential, and implications for personalized, diet-based interventions. Full article

Difficult-to-treat (D2T) rheumatoid arthritis (RA) remains a major clinical challenge, affecting a significant proportion of patients who experience persistent symptoms despite multiple therapeutic regimens. This narrative review provides a comprehensive overview of potential molecular and cellular mechanisms that may underlie the D2T RA phenotype. We synthesize evidence across a broad biological landscape—the role of genetic and epigenetic factors, autoantibodies, and diverse immune cell subsets is detailed in the context of therapeutic resistance. Furthermore, we examine the potential role of synovial signatures and stromal cell-mediated pathways, which may drive chronicity independently of traditional immune targets. The review highlights the complex interplay of peripheral and central determinants that contribute to patient-reported outcomes such as pain. We also discuss comorbid conditions, environmental factors such as smoking and nutrition, and treatment-related factors relevant to the D2T population. By integrating these aspects, this work aims to facilitate better stratification and the identification of novel therapeutic targets for refractory disease. Full article

Inflammatory bone loss is a shared pathological feature of chronic diseases such as periodontitis (PD) and rheumatoid arthritis (RA). Despite affecting distinct tissues, these diseases exhibit a bidirectional association and converge on common immune-mediated mechanisms of bone resorption. To uncover the molecular drivers underlying bone destruction across inflammatory comorbidities, we combined bioinformatic analyses with experimental validation, using PD and RA as clinically relevant models of inflammatory disease comorbidities. Elevated blood lactate levels were observed in murine models of PD and RA and correlated positively with disease severity. Single-cell RNA sequencing data from PD and RA cohorts revealed upregulation of lactate metabolism-related genes in specific monocyte subsets, accompanied by enhanced pro-inflammatory signaling and osteoclastogenic programs. Using multiple machine learning approaches, SAT1, TET2 and HIF1A were identified as core lactate-related genes with strong diagnostic potential for both diseases. In vivo and in vitro experiments further validated that lactate-driven reprogramming of monocytes, marked by activation of core lactate-related genes in circulating monocytes and local macrophages, functionally connects immune activation with exacerbated bone resorption in comorbid PD and RA. Together, these findings define a lactate-driven immunometabolic axis connecting immune responses and bone remodeling and identify SAT1, TET2 and HIF1A as potential biomarkers for inflammation-related bone loss. Full article

B cells are key drivers of immune dysregulation across systemic autoimmune diseases. Among their progeny, plasmablasts occupy a uniquely revealing niche: short-lived, highly proliferative intermediates that mirror real-time B-cell activation. Their appearance in peripheral blood integrates antigenic stimulation, cytokine-driven differentiation, and aberrant germinal-center dynamics, transforming them into sensitive indicators of ongoing immunological activity. This review synthesizes current knowledge on plasmablast biology and highlights disease-specific phenotypes across systemic lupus erythematosus (SLE), primary Sjögren disease (pSjD), IgG4-related disease (IgG4-RD), ANCA-associated vasculitis (AAV), and rheumatoid arthritis (RA). We incorporate molecular insights from single-cell technologies that have uncovered previously unrecognized plasmablast subsets, metabolic states, and interferon-related signatures with prognostic and mechanistic value. Beyond descriptive immunology, plasmablasts are emerging as dynamic biomarkers capable of informing real-time clinical decisions. One of the most robustly supported applications is the prognostic interpretation of plasmablast kinetics following B-cell-depleting therapies, where early reconstitution patterns consistently predict relapse across multiple autoimmune conditions. As clinical immunology shifts from static serological markers toward kinetic, cell-based monitoring, plasmablast quantification offers a path toward precision immune surveillance. Integrating plasmablast dynamics into routine care may ultimately allow clinicians to anticipate disease flares, time therapeutic reinforcements, and transition from reactive management to preventive intervention. Full article

Background: Seronegative rheumatoid arthritis (SNRA), defined by the absence of rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA), represents 20–30% of rheumatoid arthritis cases. Once considered a milder phenotype, SNRA is now recognised as a heterogeneous entity in which a substantial subset of patients develops structural progression comparable to seropositive RA. The binary RF/ACPA-based definition is increasingly viewed as insufficient, as the broader anti-modified protein antibody (AMPA) family—including antibodies against carbamylated, acetylated and malondialdehyde–acetaldehyde–modified proteins—indicates that many “seronegative” patients may harbour unconventional humoral autoimmunity undetected by standard assays. Objectives: To synthesise contemporary insights into the epidemiology, immunopathology, diagnostic challenges and therapeutic management of SNRA, with emphasis on erosive versus non-erosive phenotypes and the implications of the AMPA paradigm. Methods: A comprehensive literature search of PubMed, Cochrane Library and Google Scholar identified randomised trials, observational cohorts and systematic reviews, with focus on studies published within the past decade. Results: SNRA displays partially distinct immune features, including lower formation of tertiary lymphoid structures and variable activation of innate inflammatory circuits. However, the traditional adaptive–versus–innate dichotomy is overly reductionist. Growing evidence suggests that unconventional humoral responses directed against non-classical post-translational modifications may be present in a proportion of RF/ACPA-negative patients. Additional qualitative dimensions—such as IgA isotypes and fine-specificity profiles—represent further heterogeneity with potential prognostic significance. Although ACPA remains the strongest predictor of erosive progression, up to one-third of seronegative patients develop erosions within five years. The 2010 ACR/EULAR criteria may delay diagnosis in SNRA. Cytokine inhibitors and JAK inhibitors show largely serostatus-independent efficacy, whereas B-cell and T-cell–targeted therapies demonstrate attenuated responses in SNRA. Conclusions: SNRA is clinically and immunologically diverse. Integrating the AMPA framework is essential for refining classification and prognostication. Distinguishing erosive from non-erosive forms may guide treatment, while future work should prioritise biomarkers predicting progression and therapeutic response. Full article

Progressive pulmonary fibrosis (PPF) is an emerging subset of fibrotic interstitial lung diseases (ILD), defined by progressive fibrosis despite standard treatment in patients with other than idiopathic pulmonary fibrosis. The international guidelines recommended the use of nintedanib for PPF, while evidence supporting pirfenidone remains insufficient. In this study, we aimed to evaluate the efficacy and safety of pirfenidone in treating PPF. In this retrospective single-center study, we analyzed clinical data from patients with PPF who were treated with pirfenidone. Lung function data from six months before and after pirfenidone treatment were collected to assess changes over time. Missing values were imputed using a general linear mixed model (GLMM) for longitudinal data analysis. Of 33 subjects, the median age was 65.0 years, and 51.5% were female. Rheumatoid arthritis-related ILD was the most common subtype (45.5%). The median daily dose of pirfenidone was 600 mg, with a median treatment duration of 7.3 months. GLMM analysis showed a significant forced vital capacity (FVC) improvement, from −114 mL in the 6 months before treatment to +47.3 mL in the 6 months after treatment (p = 0.001). All adverse events related to pirfenidone were mild. In conclusion, the use of pirfenidone in PPF can potentially reduce the rate of FVC decline in real clinical practice. Full article

COVID-19 vaccination has played a pivotal role in mitigating the global health crisis and reducing morbidity and mortality associated with SARS-CoV-2 infection. While its public health benefits are unequivocal, the unprecedented scale of vaccination—reaching billions worldwide—has also enabled the detection of rare autoimmune events, including systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes, and Guillain–Barré syndrome. Although such events occur in only a small subset of individuals, often influenced by genetic, environmental, or dosage-related factors, they underscore the importance of understanding immune tolerance mechanisms in vaccination. This review synthesizes clinical observations and immunological findings from the COVID-19 vaccination era, highlighting key mechanisms such as molecular mimicry, adjuvant-induced inflammation, bystander activation, epitope spreading, and polyclonal B cell activation. We also consider how novel vaccine platforms, particularly mRNA-based technologies, may influence immune regulation and self-tolerance. Importantly, we discuss the therapeutic management of vaccine-associated autoimmunity, including the use of corticosteroids, intravenous immunoglobulin (IVIG), plasma exchange, disease-modifying anti-rheumatic drugs (DMARDs), and other immunosuppressive agents, many of which have led to favorable clinical outcomes. By integrating mechanistic insights with treatment strategies, this review emphasizes that the overall benefits of COVID-19 vaccination overwhelmingly outweigh the risks, while advocating for continued surveillance, mechanistic research, and risk stratification to inform safer and more targeted vaccination strategies in future pandemics. Full article

Background/Objectives: Cardiovascular disease (CVD) is the leading cause of mortality in patients with rheumatoid arthritis (RA), not fully explained by traditional risk factors and disease activity alone. This study explored the relationship between circulating monocyte subsets, inflammatory cytokine profiles, and Mammalian Target of Rapamycin Complex (mTORC) signaling in RA patients with and without a history of CVD. Methods: Peripheral blood mononuclear cells from 9 RA patients with prior CVD, 9 carefully matched RA controls without CVD, and 6 healthy controls were analyzed by flow cytometry. Matching was rigorously conducted across clinically relevant variables, including age, sex, blood pressure, lipid profile, smoking status, RA duration, disease activity, Disease-Modifying Anti-Rheumatic Drug (DMARD) failures, and steroid use. Monocyte subsets were classified as inflammatory (CD14⁺HLA-DR⁺CCR2⁺) and non-inflammatory (CD14⁺CD163⁺CCR2⁻). Results: RA-CVD⁺ patients exhibited higher frequencies of inflammatory monocytes and elevated intracellular levels of Interleukin 1 β (IL-1β) and Interleukin 6 (IL-6) compared to RA-CVD⁻ patients and healthy controls. mTORC activation, assessed by phosphorylation of S6 Ribosomal Protein (S6Rp), was significantly increased in inflammatory monocytes from RA-CVD⁺ patients. Conclusions: S6Rp correlated with IL-1β and IL-6 levels only in the RA-CVD⁺ group, suggesting a link between mTORC activity and inflammatory monocyte function. Notably, these inflammatory features did not correlate with disease activity scores or disease duration. We observed increased mTORC1 signaling in inflammatory monocytes in RA-CVD⁺ patients, suggesting a potential association with cardiovascular comorbidity. Full article

Macrophages play a central role in joint inflammation and bone destruction in rheumatoid arthritis (RA). While activator protein-1 (AP-1) transcription factors have been implicated in RA pathogenesis, the specific roles of individual AP-1 members in regulating synovial macrophages remain unclear. To address this, two public single-cell transcriptomic datasets were first analyzed to profile synovial macrophages, and then to identify AP-1 family members and associated pathways via differential expression and gene set enrichment analyses. JUND, FOSL2, and FOSB were found to be highly enriched in the RA synovium, and a distinct CXCL3⁺FOSL2⁺ macrophage subset was identified, characterized by pro-inflammatory, metabolic, and differentiation-related pathways. Intercellular communication analysis further revealed that this CXCL3⁺FOSL2⁺ macrophage subset interacted with ACKR1⁺ endothelial cells within the synovial microenvironment. Validation in a large-cohort bulk transcriptomic dataset, together with functional assays using in vitro FOSL2 knockdown in U937 cell lines, further confirmed FOSL2’s role in promoting macrophage-driven inflammation. Collectively, these findings indicate that CXCL3⁺FOSL2⁺ macrophages drive RA synovitis via the FOSL2/AP-1 axis, highlighting a potential therapeutic target. Full article

Neutrophils, a first-line defender, has a multifaceted presence in chronic inflammation, autoimmune pathology, and tumor progression. The microenvironmental cues facilitate functional plasticity and phenotypic heterogeneity to neutrophils that enable both their protective and pathogenic roles. Autoimmune diseases including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and juvenile idiopathic arthritis (JIA) display the presence of dysregulated subsets of neutrophil, such as low-density granulocytes (LDGs) that promote proinflammation and contribute to tissue damage via NETosis and type I interferon-mediated signaling. In cancer, particularly tumors, they exhibit tumor-associated neutrophils (TANs) which may polarize either towards anti-tumorigenic ‘N1’ or pro-tumorigenic ‘N2’ phenotypes based on available modulators such as TGF-β and leucine-driven epigenetic modifications. The development in neutrophil biology has introduced several novel therapeutic strategies that allow NET targeting, inhibition of chemokine receptors like CXCR2, and exploration of neutrophil-derived biomarkers for diagnosis and disease monitoring. Such findings encourage the importance of neutrophils as both effectors and therapeutic targets in inflammatory and neoplastic conditions. Full article

Introduction: Rheumatoid arthritis (RA) is known to affect the musculoskeletal system and, consequently, may lead to sarcopenia, but the role of respiratory muscle involvement in RA patients is unclear. Methods: This prospective, exploratory, single-center, matched-pair analysis study was designed to compare respiratory muscle strength and handgrip strength in RA patients and controls. Results: RA patients with low disease activity as estimated from the Disease Activity Score 28 (2.3 ± 1.2) and without signs of interstitial lung disease (n = 36, 72% female, 28% smoker, mean age 48 + 15 years, mean forced vital capacity 3.9 ± 1.0 L, 98% ± 11% predicted) and control subjects (n = 36, 72% female, 11% smoker, mean age 48 + 14 years, mean forced vital capacity 4.1 ± 1.1 L, 98% ± 16% predicted) were well balanced. Maximal inspiratory mouth pressure (PImax, primary endpoint) tended to be lower in RA patients, but this was statistically not significant (−0.9 kPa; 95%CI = −2.11/0.32). However, RA patients more frequently had PImax values below the lower limit of normal (OR 1.74 kPa; 95% CI 0.65/4.77). RA patients had lower handgrip strength (−5.97 kg; 95%CI = −9.43/−2.50). In addition, PImax was correlated to handgrip strength both in RA patients (R = 0.51, p = 0.0017) and controls (R = 0.48, p = 0.0029) and to the 6-minute walking distance (RA-patients: R = 0.30, p = 0.075; controls: R = 0.52, p = 0.0012). Conclusions: Even though the primary endpoint has not been reached, an impairment of respiratory muscle strength in RA cannot be excluded at least in a subset of patients. Further studies also involving RA patients with more disease activity are needed. Full article

Background/Objectives: Recombinant Fc proteins have been produced that have a protective effect in mouse models of arthritis, such as the K/BxN rheumatoid arthritis model. We have previously shown that a recombinant human IgG1 Fc with a point mutation at position 309, replacing a leucine with a cysteine, fused to the human IgM tailpiece to form a human IgG1 Fc hexamer, rFc-µTP-L309C, effectively prevents neutrophil infiltration into the joints and ameliorates arthritis in the K/BxN serum transfer model and in the endogenous chronic arthritis K/BxN model. We have now investigated the effect of rFc-µTP-L309C on T-cells in the K/BxN chronic arthritis mouse model. Methods: PBMCs were isolated from the spleen, lymph nodes and joint synovial fluid from K/BxN mice having severe chronic arthritis that had been treated with 200 mg/kg rFc-µTP-L309C or human serum albumin (HSA). Flow cytometry was used to isolate the activated CD4⁺CD44⁺ T-cells and T-regulatory cells (Tregs). Intracellular staining was used to identify Th1 and Th17 T-cell subsets, and CD4⁺CD25⁺FoxP3⁺ Tregs. ELISA was used to measure levels of IL-10 and TGF-β in synovial fluid. Results: We find that amelioration of the arthritis occurs after treatment with rFc-µTP-L309C and results in a decrease in Th1 cells’ production of IFNγ and Th17 cells’ production of IL-17. Amelioration also results in decreased production of GM-CSF. Moreover, amelioration results in increased Tregs and IL-10 production in the synovial fluid. Conclusions: rFc-µTP-L309C reduces the inflammatory T-cells and increases the regulatory anti-inflammatory T-cells in the chronic arthritis K/BxN mouse model. This effect explains, in part, the ability of rFc-µTP-L309C to ameliorate the arthritis and reduce damage on the articular cartilage of K/BxN mice. Full article