Autoantibodies against chemokines post-SARS-CoV-2 infection correlate with disease course.

Infection with severe acute respiratory syndrome coronavirus 2 associates with diverse symptoms, which can persist for months. While antiviral antibodies are protective, those targeting interferons and other immune factors are associated with adverse coronavirus disease 2019 (COVID-19) outcomes. Here we discovered that antibodies against specific chemokines were omnipresent post-COVID-19, were associated with favorable disease outcome and negatively correlated with the development of long COVID at 1 yr post-infection. Chemokine antibodies were also present in HIV-1 infection and autoimmune disorders, but they targeted different chemokines compared with COVID-19. Monoclonal antibodies derived from COVID-19 convalescents that bound to the chemokine N-loop impaired cell migration. Given the role of chemokines in orchestrating immune cell trafficking, naturally arising chemokine antibodies may modulate the inflammatory response and thus bear therapeutic potential.

Synovial and serum B-cell signature of autoantibody-negative rheumatoid arthritis versus autoantibody-positive rheumatoid arthritis and psoriatic arthritis.

OBJECTIVES: Autoantibody-negative rheumatoid arthritis (RA) differs from autoantibody-positive RA in several clinical aspects, possibly underpinned by pathogenetic differences. At present, the role of adaptive immune responses in autoantibody-negative RA remains unclear. Here, we investigated the synovial and serum immunophenotype indicative of B-lymphocyte involvement across the spectrum of autoantibody-positive and -negative chronic arthritides. METHODS: Ultrasound-guided synovial biopsies were retrieved from 131 patients: 43 autoantibody-positive RA, 35 autoantibody-negative RA, 25 polyarticular psoriatic arthritis (PsA), 28 oligoarticular PsA. Samples were analysed for the degree of histological inflammation, B-lymphocyte infiltration and the distribution of different pathotypes (lympho-myeloid, myeloid, pauci-immune). Serum levels of the B-cell chemoattractant CXCL13 were compared among groups. RESULTS: Synovitis scores and CD68+ sublining macrophage infiltration were comparable irrespective of clinical diagnosis and disease subtype. In contrast, the degree of B-lymphocyte infiltration and the frequency of lympho-myeloid synovitis in autoantibody-negative RA were lower than those of autoantibody-positive RA (mean [SD] 1.8 [1] vs 2.4 [0.6], p = 0.03 and 38.2% vs 62.9%, p = 0.07, respectively), and similar to polyarticular PsA. Oligoarticular PsA had the lowest B-cell scores. Serum CXCL13 was associated with lympho-myeloid synovitis and followed a similar gradient, with the highest levels in autoantibody-positive RA, intermediate and comparable levels in autoantibody-negative RA and polyarticular PsA, and low levels in oligoarticular PsA. CONCLUSIONS: The synovial and serum immunophenotype indicative of B-lymphocyte involvement in autoantibody-negative RA differs from autoantibody-positive RA and more closely resembles that observed in polyarticular PsA. The pathobiological stratification of chronic inflammatory arthritides beyond clinical diagnosis may fuel personalised treatment strategies.

Seronegative rheumatoid arthritis: one year in review 2023.

In the past 20 years, earlier diagnosis and more intensive management have considerably improved the prognosis of rheumatoid arthritis (RA), with milder disease course achieved in particular in seropositive patients. In contrast, seronegative RA has remained largely neglected, and continues to be surrounded by uncertainties regarding its correct diagnosis, clinical phenotype, optimal treatment strategies and relevant outcomes.The purpose of this review is to summarise new insights about the pathogenic, clinical and prognostic peculiarities of seronegative RA that emerged during 2022, and that make this disease subset at least partially different from its seropositive counterpart.

Reactogenicity, safety and disease flares following BNT162b2 mRNA COVID-19 vaccine in patients with chronic immune-inflammatory arthritis treated with biological and targeted synthetic disease-modifying anti-rheumatic drugs.

OBJECTIVES: The safety of COVID-19 vaccination in rheumatic patients treated with biological (b) and targeted synthetic (ts) disease-modifying anti-rheumatic drugs (DMARDs) remains poorly explored. METHODS: Reactogenicity, safety and disease flares following each of the two doses of the BNT162b2 mRNA vaccine was evaluated in 186 patients with rheumatoid arthritis, psoriatic arthritis and spondyloarthritis treated with b/tsDMARDs, who discontinued anti-rheumatic treatments around vaccination. A group of 53 healthy controls was used for comparison. RESULTS: The frequency and severity of systemic events was similar to that reported in the general population, and no particular safety concerns emerged. The use of methotrexate reduced systemic reactogenicity (adjORs [95% CI] 0.49 [0.25-0.94] and 0.63 [0.32-0.99] after each vaccine dose), whilst no specific effects of different b/tsDMARDs were seen. Flares around vaccination were reported by 24.5% of the patients. Factors associated with flares were active disease (adjORs [95% CI] 2.8 [1.01-8.09] and 1.86 [0.99-6.03] after each vaccine dose) and use of JAKi (adjORs [95% CI] 3.96 [1.39-11.27] and 3.10 [0.99-7.85]). The percentage of cases requiring change or increase in DMARD therapy due to persistent worsening of disease activity at follow-up visits was low (3.2%). CONCLUSIONS: The safety of mRNA COVID-19 vaccination in arthritis patients on treatment with b/tsDMARDs is reassuring. In a regimen of peri-vaccine drug interruption, transient flares of the disease more commonly occur in association with active arthritis and use of shorter half-life drugs. Most flares do not require treatment escalation or change.

Inflammatory correlates of the Patient Global Assessment of Disease Activity vary in relation to disease duration and autoantibody status in patients with rheumatoid arthritis.

OBJECTIVE: To investigate the associations between the Patient Global Assessment (PGA) and measures of disease activity in patients with rheumatoid arthritis (RA) in relation to disease duration and autoantibody status. METHODS: 1412 patients from three independent cohorts were studied: a prospective cohort of 810 patients with early RA followed up for 24 months; a cross-sectional cohort of 210 patients with established RA in low disease activity; a cross-sectional cohort of 401 patients with established RA in moderate-to-high disease activity. Correlations of the PGA were analysed by Pearson's coefficients and multivariable linear regression at baseline and at months 6, 12 and 24 in the overall populations and after stratification for autoantibody subgroup and remission status (Boolean remission, PGA near remission and non-remission). RESULTS: In patients with early RA in non-remission, swollen joints correlated independently with the PGA; the correlation became progressively weaker but persisted at all time points in autoantibody-positive patients (adjusted r=0.30-0.12) but lost significance after month 12 in autoantibody-negative patients. Swollen joints independently correlated with the PGA also in near remission until month 12 (adjusted r=0.18-0.16) in autoantibody-positive patients. No independent correlations of inflammatory variables were instead found in patients with established RA irrespective of disease activity and autoantibody status. CONCLUSIONS: In the early phases of RA, particularly in autoantibody-positive patients, inflammatory variables directly correlate with the PGA across different disease activity states. The optimal cut-off values of the PGA capable of identifying absence of disease should be better explored in relation to disease duration and autoantibody status.

Targeting the IL-6-Yap-Snail signalling axis in synovial fibroblasts ameliorates inflammatory arthritis.

OBJECTIVE: We aimed to understand the role of the transcriptional co-factor Yes-associated protein (Yap) in the molecular pathway underpinning the pathogenic transformation of synovial fibroblasts (SF) in rheumatoid arthritis (RA) to become invasive and cause joint destruction. METHODS: Synovium from patients with RA and mice with antigen-induced arthritis (AIA) was analysed by immunostaining and qRT-PCR. SF were targeted using Pdgfrα-CreER and Gdf5-Cre mice, crossed with fluorescent reporters for cell tracing and Yap-flox mice for conditional Yap ablation. Fibroblast phenotypes were analysed by flow cytometry, and arthritis severity was assessed by histology. Yap activation was detected using Yap-Tead reporter cells and Yap-Snail interaction by proximity ligation assay. SF invasiveness was analysed using matrigel-coated transwells. RESULTS: Yap, its binding partner Snail and downstream target connective tissue growth factor were upregulated in hyperplastic human RA and in mouse AIA synovium, with Yap detected in SF but not macrophages. Lineage tracing showed polyclonal expansion of Pdgfrα-expressing SF during AIA, with predominant expansion of the Gdf5-lineage SF subpopulation descending from the embryonic joint interzone. Gdf5-lineage SF showed increased expression of Yap and adopted an erosive phenotype (podoplanin+Thy-1 cell surface antigen-), invading cartilage and bone. Conditional ablation of Yap in Gdf5-lineage cells or Pdgfrα-expressing fibroblasts ameliorated AIA. Interleukin (IL)-6, but not tumour necrosis factor alpha (TNF-α) or IL-1ß, Jak-dependently activated Yap and induced Yap-Snail interaction. SF invasiveness induced by IL-6 stimulation or Snail overexpression was prevented by Yap knockdown, showing a critical role for Yap in SF transformation in RA. CONCLUSIONS: Our findings uncover the IL-6-Yap-Snail signalling axis in pathogenic SF in inflammatory arthritis.

EULAR points to consider for minimal reporting requirements in synovial tissue research in rheumatology.

BACKGROUND: Synovial tissue research has become widely developed in several rheumatology centres, however, large discrepancies exist in the way synovial tissue is handled and, more specifically, how data pertaining to biopsy procedure, quality check and experimental results are reported in the literature. This heterogeneity hampers the progress of research in this rapidly expanding field. In that context, under the umbrella of European Alliance of Associations for Rheumatology, we aimed at proposing points to consider (PtC) for minimal reporting requirements in synovial tissue research. METHODS: Twenty-five members from 10 countries across Europe and USA met virtually to define the key areas needing evaluation and formulating the research questions to inform a systematic literature review (SLR). The results were presented during a second virtual meeting where PtC were formulated and agreed. RESULTS: Study design, biopsy procedures, tissue handling, tissue quality control and tissue outcomes (imaging, DNA/RNA analysis and disaggregation) were identified as important aspects for the quality of synovial tissue research. The SLR interrogated four databases, retrieved 7654 abstracts and included 26 manuscripts. Three OPs and nine PtC were formulated covering the following areas: description of biopsy procedure, overarching clinical design, patient characteristics, tissue handling and processing, quality control, histopathology, transcriptomic analyses and single-cell technologies. CONCLUSIONS: These PtC provide guidance on how research involving synovial tissue should be reported to ensure a better evaluation of results by readers, reviewers and the broader scientific community. We anticipate that these PtC will enable the field to progress in a robust and transparent manner over the coming years.

The Genetic, Environmental, and Immunopathological Complexity of Autoantibody-Negative Rheumatoid Arthritis.

Differences in clinical presentation, response to treatment, and long-term outcomes between autoantibody-positive and -negative rheumatoid arthritis (RA) highlight the need for a better comprehension of the immunopathogenic events underlying the two disease subtypes. Whilst the drivers and perpetuators of autoimmunity in autoantibody-positive RA have started to be disclosed, autoantibody-negative RA remains puzzling, also due its wide phenotypic heterogeneity and its possible misdiagnosis. Genetic susceptibility appears to mostly rely on class I HLA genes and a number of yet unidentified non-HLA loci. On the background of such variable genetic predisposition, multiple exogeneous, endogenous, and stochastic factors, some of which are not shared with autoantibody-positive RA, contribute to the onset of the inflammatory cascade. In a proportion of the patients, the immunopathology of synovitis, at least in the initial stages, appears largely myeloid driven, with abundant production of proinflammatory cytokines and only minor involvement of cells of the adaptive immune system. Better understanding of the complexity of autoantibody-negative RA is still needed in order to open new avenues for targeted intervention and improve clinical outcomes.

Counter-regulation of regulatory T cells by autoreactive CD8+ T cells in rheumatoid arthritis.

The mechanisms whereby autoreactive T cells escape peripheral tolerance establishing thus autoimmune diseases in humans remain an unresolved question. Here, we demonstrate that autoreactive polyfunctional CD8+ T cells recognizing self-antigens (i.e., vimentin, actin cytoplasmic 1, or non-muscle myosin heavy chain 9 epitopes) with high avidity, counter-regulate Tregs by killing them, in a consistent percentage of rheumatoid arthritis (RA) patients. Indeed, these CD8+ T cells express a phenotype and gene profile of effector (eff) cells and, upon antigen-specific activation, kill Tregs indirectly in an NKG2D-dependent bystander fashion in vitro. This data provides a mechanistic basis for the finding showing that AE-specific (CD107a+) CD8+ T killer cells correlate, directly with the disease activity score, and inversely with the percentage of activated Tregs, in both steady state and follow-up studies in vivo. In addition, multiplex immunofluorescence imaging analyses of inflamed synovial tissues in vivo show that a remarkable number of CD8+ T cells express granzyme-B and selectively contact FOXP3+ Tregs, some of which are in an apoptotic state, validating hence the possibility that CD8+ Teff cells can counteract neighboring Tregs within inflamed tissues, by killing them. Alternatively, the disease activity score of a different subset of patients is correlated with the expansion of a peculiar subpopulation of autoreactive low avidity, partially-activated (pa)CD8+ T cells that, despite they conserve the conventional naïve (N) phenotype, produce high levels of tumor necrosis factor (TNF)-α and exhibit a gene expression signature of a progressive activation state. Tregs directly correlate with the expansion of this autoreactive (low avidity) paCD8+ TN cell subset in vivo, and efficiently control their differentiation rather their proliferation in vitro. Interestingly, autoreactive high avidity CD8+ Teff cells or low avidity paCD8+ TN cells are significantly expanded in RA patients who would become non-responders or patients who would become responders to TNF-α inhibitor therapy, respectively. These data provide evidence of a previously undescribed role of such mechanisms in the progression and therapy of RA.

Potential involvement of IL-9 and Th9 cells in the pathogenesis of rheumatoid arthritis.

OBJECTIVE: IL-9 has been shown to be upregulated before the clinical onset of articular disease in RA. The exact role of IL-9 and Th9 cells in RA, however, has not yet been adequately studied. The aim of this study was to evaluate the expression of IL-9 and IL-9-expressing cells in RA patients. METHODS: IL-9, IL-9R, PU.1, IL-9, thymic stromal lymphopoietin (TSLP), IL-4 and TGF-ß expression was assessed by real-time-PCR in the synovial tissues of RA and OA patients. IL-9, IL-9R, IL-4, TSLP and TGF-ß were also investigated by immunohistochemistry. Peripheral CD4(+) T cell subsets were studied by flow cytometry analysis before and after incubation with citrullinated peptides. RESULTS: IL-9 was overexpressed in RA synovial tissues and correlated with the degree of histological organization of B and T cells in ectopic lymphoid structures. The majority of IL-9-producing cells were identified as CD3(+) cells. Increased mRNA and protein expression of IL-9R, IL-4, TSLP and TGF-ß was also observed in RA synovial tissue. Blood peripheral Th9 cells were expanded by citrullinated peptides. CONCLUSION: These results indicate that Th9 cells and IL-9 were frequently detected in peripheral blood mononuclear cells and synovia of RA patients. A possible pathogenic role for Th9 in RA is discussed.

Neuroprotective effects of the Sigma-1 receptor (S1R) agonist PRE-084, in a mouse model of motor neuron disease not linked to SOD1 mutation.

The identification of novel molecular targets crucially involved in motor neuron degeneration/survival is a necessary step for the development of hopefully more effective therapeutic strategies for amyotrophic lateral sclerosis (ALS) patients. In this view, S1R, an endoplasmic reticulum (ER)-resident receptor with chaperone-like activity, has recently attracted great interest. S1R is involved in several processes leading to acute and chronic neurodegeneration, including ALS pathology. Treatment with the S1R agonist PRE-084 improves locomotor function and motor neuron survival in presymptomatic and early symptomatic mutant SOD1-G93A ALS mice. Here, we tested the efficacy of PRE-084 in a model of spontaneous motor neuron degeneration, the wobbler mouse (wr) as a proof of concept that S1R may be regarded as a key therapeutic target also for ALS cases not linked to SOD1 mutation. Increased staining for S1R was detectable in morphologically spared cervical spinal cord motor neurons of wr mice both at early (6th week) and late (12th week) phases of clinical progression. S1R signal was also detectable in hypertrophic astrocytes and reactive microglia of wr mice. Chronic treatment with PRE-084 (three times a week, for 8weeks), starting at symptom onset, significantly increased the levels of BDNF in the gray matter, improved motor neuron survival and ameliorated paw abnormality and grip strength performance. In addition, the treatment significantly reduced the number of reactive astrocytes whereas, that of CD11b+ microglial cells was increased. A deeper evaluation of microglial markers revealed significant increased number of cells positive for the pan-macrophage marker CD68 and of CD206+ cells, involved in tissue restoration, in the white matter of PRE-084-treated mice. The mRNA levels of TNF-α and IL-1ß were not affected by PRE-084 treatment. Thus, our results support pharmacological manipulation of S1R as a promising strategy to cure ALS and point to increased availability of growth factors and modulation of astrocytosis and of macrophage/microglia as part of the mechanisms involved in S1R-mediated neuroprotection.

High expression levels of the B cell chemoattractant CXCL13 in rheumatoid synovium are a marker of severe disease.

OBJECTIVE: The B cell chemoattractant chemokine ligand 13 (CXCL13) is emerging as a new biochemical marker in RA. This study was undertaken to dissect the relationship between CXCL13 expression levels in the synovium and clinico-pathological variables relevant to RA pathogenesis and outcome. METHODS: Synovial tissues from 71 RA patients were evaluated by immunohistochemistry. Thirty paired samples were used for comparative gene expression analysis by quantitative real-time PCR. CXCL13 levels were analysed in relation to cellular, molecular and clinical features of inflammation, lymphocyte activation and joint damage. RESULTS: In patients with early disease (<12 months duration), CXCL13 expression correlated significantly with synovial markers of local disease activity and systemic inflammation. Such correlation was less evident in established RA. Notably, the association with lymphocyte infiltration and with expression of B/T cell-related activation and proliferation genes, such as activation-induced cytidine deaminase, IFN-γ and IL-2, remained highly significant independent of disease duration and local disease activity. Patients featuring the highest levels of CXCL13 were more frequently ACPA positive and IgG ACPA titres were increased in the high CXCL13 expression group. Furthermore, the frequency of erosive disease on radiographs was significantly higher in the upper tertile of CXCL13 expression (P = 0.01 with adjustment for disease duration and ACPA). Accordingly, synovial CXCL13 and the local receptor activator of nuclear factor κB ligand (RANKL)/osteoprotegerin (OPG) ratio significantly co-varied (ρ = 0.52, P < 0.01), independent of the level of local inflammation. CONCLUSION: Synovial CXCL13 appears to be a marker of a more severe pattern of RA disease, characterized by increased lymphocyte activation and bone remodelling beyond the level of conventional markers of inflammation.

Secondary and ectopic lymphoid tissue responses in rheumatoid arthritis: from inflammation to autoimmunity and tissue damage/remodeling.

Rheumatoid arthritis is a chronic systemic inflammatory disease primarily affecting the synovium of diarthrodial joints. Despite the currently unknown etiology, overwhelming evidence indicates that both innate and adaptive immunity play a central role in disease pathogenesis. In this review, we consider recent evidence examining the mechanisms of lymphoid tissue reactivity in rheumatoid arthritis with a focus on the dynamics controlling secondary and ectopic lymphoid tissue response. We then examine the cellular and molecular mechanisms regulating the biopathology of these processes with specific emphasis on cell trafficking, contribution to autoimmunity, and joint damage-repair. We finally provide a brief overview of the most recent studies addressing the clinical relevance of synovial lymphoid tissue analysis as a diagnostic and prognostic tool as well as its response to current biological therapies.

The access route through the anatomical snuffbox in ultrasound-guided synovial biopsy of the wrist allows for a safe and effective collection of tissue samples in inflammatory arthritis.

BACKGROUND: A proof-of-concept study to evaluate the feasibility and safety of minimally invasive ultrasound (US)-guided synovial biopsy of the radiocarpal (RC) joint using the anatomical snuffbox as an access route. METHODS: Twenty consecutive patients with active chronic arthritis of the wrist underwent minimally invasive US-guided synovial biopsy of the RC joint using the anatomical snuffbox as the access route. Samples were retrieved from 3 predetermined biopsy target sites of the RC synovia (proximal, vault, and distal site), aiming for a minimum of 12 samples. The procedure's feasibility was evaluated based on the number and histological quality of retrieved tissue fragments tested on pre-defined histometric parameters. The safety and tolerability of the procedure were assessed through 1-week and 1-month follow-up clinical evaluations. RESULTS: A median number of 17 fragments (≥ 1 mm diameter size at macroscopic evaluation) per procedure was processed for histopathology (range 9-24) and dedicated to the study. At the histopathologic evaluation, a gradable tissue (visible lining layer and ≥ 4 fragments with IST) was recognized in 19/20 biopsies (95%), and all pre-defined histometric parameters were judged applicable and successfully measured in 19/19 gradable biopsies. All three biopsy target sites showed sampling accessibility. The entire procedure was generally well tolerated. At the 1-month follow-up, no patients showed infectious complications. CONCLUSIONS: The access route through the anatomical snuff box in US-guided synovial biopsies of the RC joint allows for a safe and targeted collection of adequate tissue samples. This modification of the traditional access route may allow easier, repeatable, and safer sampling of anatomically distinct areas of the wrist in the course of arthritis.

Insights Into the Concept of Rheumatoid Arthritis Flare.

Identification of a pathological change in the course of systemic chronic immune-inflammatory diseases is key to delivering effective treatment strategies. In this context, one of the most compelling issues is the concept of flare. The multifaceted expression of disease activity in rheumatoid arthritis (RA) makes it challenging to provide an omni-comprehensive definition of flare, encompassing the pathology's different objective and subjective domains. Our incomplete understanding of the pathophysiological mechanisms underlying this process contributes to the partial comprehension of its potential clinical expression. This review focuses on the proposed pathophysiological processes underlying disease recrudescence in RA and the variable definitions adopted to capture flare in clinical practice through its objective, subjective, and temporal domains. Overall, what emerges is a complex landscape far from being unraveled.

Anti-chemokine antibodies after SARS-CoV-2 infection correlate with favorable disease course.

Infection by SARS-CoV-2 leads to diverse symptoms, which can persist for months. While antiviral antibodies are protective, those targeting interferons and other immune factors are associated with adverse COVID-19 outcomes. Instead, we discovered that antibodies against specific chemokines are omnipresent after COVID-19, associated with favorable disease, and predictive of lack of long COVID symptoms at one year post infection. Anti-chemokine antibodies are present also in HIV-1 infection and autoimmune disorders, but they target different chemokines than those in COVID-19. Monoclonal antibodies derived from COVID- 19 convalescents that bind to the chemokine N-loop impair cell migration. Given the role of chemokines in orchestrating immune cell trafficking, naturally arising anti-chemokine antibodies associated with favorable COVID-19 may be beneficial by modulating the inflammatory response and thus bear therapeutic potential. One-Sentence Summary: Naturally arising anti-chemokine antibodies associate with favorable COVID-19 and predict lack of long COVID.