Effectiveness and safety of filgotinib in rheumatoid arthritis patients: data from the GISEA registry.

OBJECTIVES: The aim of this study was to evaluate the effectiveness and safety profile of filgotinib, a JAK1 preferential inhibitor, in rheumatoid arthritis (RA) patients included in Italian GISEA (Group for the Study of Early Arthritis) registry. METHODS: Data from RA patients treated with filgotinib, recorded in the GISEA registry, were analysed. Disease activity scores and patient-reported outcomes (PROs) were assessed at baseline, as well as during 12-month follow-up. A difficult-to-treat (D2T) RA patient was defined according with EULAR criteria. Retention rate of filgotinib was estimated by the Kaplan-Meier method and factors influencing drug discontinuation were estimated by Cox regression models. RESULTS: 246 RA patients (female 89%, 57.6±12.2 years old) started filgotinib, mostly as second (22%) or further (43.9%) b/tsDMARDs line of treatment. At 3 and 12 months, 18.8% and 27.5% of patients achieved Clinical Diseases Activity Index based remission and 30.1% and 37.7% obtained a visual analogue scale of pain ≤20 (all p<0.01 vs. baseline). Filgotinib survival rate was 84.5% at the 6-month and 75.8% at 12-month follow-up, and was comparable either in monotherapy or combination therapy, and irrespective of glucocorticoid intake. b/tsDMARD naive patients had the lowest hazard ratio (HR) of filgotinib discontinuation (HR 0.29, 95%CI 0.14-0.64), while D2T-RA the highest (HR 1.82, 95%CI 1.01-3.3). Eight patients (3.3%) discontinued filgotinib due to adverse events. CONCLUSIONS: In an Italian real-life setting, filgotinib is confirmed to be safe and with a good effectiveness profile both in monotherapy and without glucocorticoids.

The Systemic Score May Identify Life-Threatening Evolution in Still Disease: Data from the GIRRCS AOSD-Study Group and the AIDA Network Still Disease Registry.

OBJECTIVE: We aimed to evaluate the clinical usefulness of the systemic score in the prediction of life-threatening evolution in Still disease. We also aimed to assess the clinical relevance of each component of the systemic score in predicting life-threatening evolution and to derive patient subsets accordingly. METHODS: A multicenter, observational, prospective study was designed including patients included in the Gruppo Italiano Di Ricerca in Reumatologia Clinica e Sperimentale Adult-Onset Still Disease Study Group and the Autoinflammatory Disease Alliance Network Still Disease Registry. Patients were assessed to see if the variables to derive the systemic score were available. The life-threatening evolution was defined as mortality, whatever the clinical course, and/or macrophage activation syndrome, a secondary hemophagocytic lymphohistiocytosis associated with a poor prognosis. RESULTS: A total of 597 patients with Still disease were assessed (mean ± SD age 36.6 ± 17.3 years; male 44.4%). The systemic score, assessed as a continuous variable, significantly predicted the life-threatening evolution (odds ratio [OR] 1.24; 95% confidence interval [CI] 1.07-1.42; P = 0.004). A systemic score ≥7 also significantly predicted the likelihood of a patient experiencing life-threatening evolution (OR 3.36; 95% CI 1.81-6.25; P < 0.001). Assessing the clinical relevance of each component of the systemic score, liver involvement (OR 1.68; 95% CI 1.48-2.67; P = 0.031) and lung disease (OR 2.12; 95% CI 1.14-4.49; P = 0.042) both significantly predicted life-threatening evolution. The clinical characteristics of patients with liver involvement and lung disease were derived, highlighting their relevance in multiorgan disease manifestations. CONCLUSION: The clinical utility of the systemic score was shown in identifying Still disease at a higher risk of life-threatening evolution in a large cohort. Furthermore, the clinical relevance of liver involvement and lung disease was highlighted.

Efficacy of canakinumab in patients with Still's disease across different lines of biologic therapy: real-life data from the International AIDA Network Registry for Still's Disease.

Introduction: The effectiveness of canakinumab may change according to the different times it is used after Still's disease onset. This study aimed to investigate whether canakinumab (CAN) shows differences in short- and long-term therapeutic outcomes, according to its use as different lines of biologic treatment. Methods: Patients included in this study were retrospectively enrolled from the AutoInflammatory Disease Alliance (AIDA) International Registry dedicated to Still's disease. Seventy-seven (51 females and 26 males) patients with Still's disease were included in the present study. In total, 39 (50.6%) patients underwent CAN as a first-line biologic agent, and the remaining 38 (49.4%) patients were treated with CAN as a second-line biologic agent or subsequent biologic agent. Results: No statistically significant differences were found between patients treated with CAN as a first-line biologic agent and those previously treated with other biologic agents in terms of the frequency of complete response (p =0.62), partial response (p =0.61), treatment failure (p >0.99), and frequency of patients discontinuing CAN due to lack or loss of efficacy (p =0.2). Of all the patients, 18 (23.4%) patients experienced disease relapse during canakinumab treatment, 9 patients were treated with canakinumab as a first-line biologic agent, and nine patients were treated with a second-line or subsequent biologic agent. No differences were found in the frequency of glucocorticoid use (p =0.34), daily glucocorticoid dosage (p =0.47), or concomitant methotrexate dosage (p =0.43) at the last assessment during CAN treatment. Conclusion: Canakinumab has proved to be effective in patients with Still's disease, regardless of its line of biologic treatment.

Derivation and validation of four patient clusters in Still's disease, results from GIRRCS AOSD-study group and AIDA Network Still Disease Registry.

BACKGROUND: Different patient clusters were preliminarily suggested to dissect the clinical heterogeneity in Still's disease. Thus, we aimed at deriving and validating disease clusters in a multicentre, observational, prospective study to stratify these patients. METHODS: Patients included in GIRRCS AOSD-study group and AIDA Network Still Disease Registry were assessed if variables for cluster analysis were available (age, systemic score, erythrocyte sedimentation rate (ESR), C reactive protein (CRP) and ferritin). K-means algorithm with Euclidean metric and Elbow plot were used to derive an adequate number of clusters. RESULTS: K-means clustering assessment provided four clusters based on means standardised according to z-scores on 349 patients. All clusters mainly presented fever, skin rash and joint involvement. Cluster 1 was composed by 115 patients distinguished by lower values of age and characterised by skin rash myalgia, sore throat and splenomegaly. Cluster 2 included 128 patients identified by lower levels of ESR, ferritin and systemic score; multiorgan manifestations were less frequently observed. Cluster 3 comprised 31 patients categorised by higher levels of CRP and ferritin, they were characterised by fever and joint involvement. Cluster 4 contained 75 patients derived by higher values of age and systemic score. Myalgia, sore throat, liver involvement and life-threatening complications, leading to a high mortality rate, were observed in these patients. CONCLUSIONS: Four patient clusters in Still's disease may be recognised by a multidimensional characterisation ('Juvenile/Transitional', 'Uncomplicated', 'Hyperferritinemic' and 'Catastrophic'). Of interest, cluster 4 was burdened by an increased rate of life-threatening complications and mortality, suggesting a more severe patient group.

Janus kinase inhibitors effectively improve pain across different disease activity states in rheumatoid arthritis.

Pain remains one of the most difficult-to-treat domains in patients with rheumatoid arthritis (RA). In clinical trials, the Janus kinase inhibitors (JAKis) have demonstrated good efficacy in pain relief. Aim of our study was to evaluate the real-life effectiveness of JAKis in improving pain in patients with RA in different states of baseline disease activity. A monocentric prospective cohort of 181 RA patients starting treatment with JAKis was studied. Pain was evaluated on a 0-100 mm visual analogue scale (VAS). Clinically meaningful improvements over 24 weeks were defined as follows: proportion of patients achieving ≥ 30%, ≥ 50%, and ≥ 70% pain relief, and remaining pain ≤ 20 or ≤ 10 mm. Results were analysed after stratification for baseline inflammatory activity; patients with swollen joints and C-reactive protein ≤ 1 at treatment start were considered pauci-inflammatory. Proportion of patients who achieved ≥ 30%, ≥ 50% and ≥ 70% pain improvement at 24 weeks was 61.4%, 49.3% and 32.9%. Furthermore, 40.6% and 28.5% of the patients achieved thresholds of remaining pain equivalent to mild pain or no/limited pain. Pain improvements were more evident in patients naive to previous biologics, although nearly 30% of multiple failures achieved VAS ≤ 20 mm. No significant differences were observed in relation to monotherapy. Pauci-inflammatory patients at treatment start achieved good outcomes, with 40.4% experiencing ≥ 70% pain improvement, and 35.7% VAS ≤ 10 mm. JAKis show efficacy in pain relief in real life. The improvement of painful symptoms also in those patients with limited objective inflammation may open new perspectives on the management of difficult-to-treat RA.

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.

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.

Tumor necrosis factor-α inhibitor-related autoimmune disorders.

Biotechnological monoclonal antibodies and receptor antagonists capable of targeting specific inflammatory actors, such as cytokines, cytokines receptors, co-stimulatory molecules or leukocyte populations, have emerged as an alternative to conventional therapies for treating systemic inflammatory diseases with immune pathogenesis. However, there is no doubt that, with a frequency that is not exceptionally high but also not negligible, immunotherapies can favour the development of systemic and organ-specific immune-mediated disorders. It has become increasingly evident that interference with a specific immune pathway may favour the activation of opposing compensatory signalling, which may exacerbate underlying subclinical disorders or cause immune-mediated diseases completely different from the underlying disease. The 'compensatory immunological switch' has emerged primarily in patients treated with tumor necrosis factor (TNF) -α inhibitors, the first biological drugs approved for treating systemic inflammatory diseases with immune pathogenesis. In this Review, we describe the clinical features and predisposing factors of the main TNF-α inhibitor-related autoimmune disorders, organising them into subclinical serological autoimmunity, autoimmune disorders other than those for which TNF-α inhibitors are indicated, and paradoxical reactions. We also discuss the underlying pathogenetic mechanisms and precautions for use in the therapeutic management of these patients. Better understanding of the complex phenomenon of the 'compensatory immunological switch', which TNF-α inhibitors and other biological drugs might trigger, can help not only appropriately managing immune-mediated disorders, but also better interpreting the heterogeneity of the pathogenetic mechanisms underlying certain chronic inflammatory conditions that, although different from each other, are arbitrarily placed in the context of overly generic nosological entities.

Clinical characteristics of obese patients with adult-onset Still's disease. Data from a large multicentre cohort.

OBJECTIVES: To evaluate the impact of obesity in patients with adult-onset Still's disease (AOSD) and to assess their clinical characteristics and disease outcomes. METHODS: The clinical features of AOSD patients with a body mass index (BMI)≥30 were assessed among those included in the multicentre Gruppo Italiano di Ricerca in Reumatologia Clinica e Sperimentale (GIRRCS) cohort. RESULTS: Out of 139 AOSD patients, who had BMI registered in our database, 26 (18.7%) had a BMI≥30. A lower rate of sore throat (P<0.05), pericarditis (P<0.05), and pleuritis (P<0.05) was shown in obese patients. Additionally, obese patients showed higher values of C-reactive protein (CRP) (P<0.05) and ferritin (P<0.05) than others. Furthermore, obese patients were characterised by biologic disease-modifying antirheumatic drug (bDMARD) failure in subsequent follow-up (P<0.05). They also presented higher rate of comorbidity than non-obese patients (P<0.05). Finally, obesity predicted the presence of a chronic disease course in both univariate (HR: 1.72, 95%CI: 1.03-2.51, P<0.05) and multivariate analyses (HR: 1.85, 95%CI: 1.45-2.89, P<0.05). Obesity was also a significant predictor of bDMARD failure in AOSD patients in both univariate (HR: 3.03, 95%CI: 1.42-6.45, P<0.01) and multivariate analyses (HR: 3.59, 95%CI: 1.55-8.27, P<0.01). CONCLUSION: Obese patients at the time of diagnosis of the disease were characterised by a lower prevalence of sore throat, serositis, as well as by higher values of CRP and ferritin. Obesity was also a predictive factor for a chronic disease course and bDMARD failure, thus highlighting a subset of patients with AOSD to be carefully managed.

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.

Autoantibody-negative rheumatoid arthritis: still a challenge for the rheumatologist.

Increased research over the past 30 years has greatly improved the understanding of the pathophysiological mechanisms and clinical aspects of autoantibody-positive rheumatoid arthritis, resulting in improved management and outcomes. In contrast, the subset of rheumatoid arthritis that does not have autoantibodies (such as rheumatoid factor and anti-citrullinated protein autoantibodies) remains less well defined in its pathogenic mechanisms. Autoantibody-negative rheumatoid arthritis continues to pose diagnostic challenges, might respond differently to therapies, and appears to be burdened with different comorbidities and outcomes. The clear separation of rheumatoid arthritis according to serotypes is still a subject of uncertainty and controversy, and studies specifically focused on comparing rheumatoid arthritis and rheumatoid arthritis-like arthritides that do not have autoantibodies remain scarce. The purpose of this Review is to summarise the peculiarities that make autoantibody-negative rheumatoid arthritis different from its autoantibody-positive counterpart, with the aim of generating debate and stimulating further research on this challenging condition.

Personalized Therapeutic Strategies in the Management of Osteoporosis in Patients with Autoantibody-Positive Rheumatoid Arthritis.

Bone mineral density (BMD) reduction and fragility fractures still represent a major source of morbidity in rheumatoid arthritis (RA) patients, despite adequate control of the disease. An increasing number of clinical and experimental evidence supports the role of autoantibodies, especially anti-citrullinated protein antibodies (ACPAs), in causing localized and generalised bone loss in ways that are both dependent on and independent of inflammation and disease activity. The human receptor activator of nuclear factor kappa B and its ligand-the so-called RANK-RANKL pathway-is known to play a key role in promoting osteoclasts' activation and bone depletion, and RANKL levels were shown to be higher in ACPA-positive early untreated RA patients. Thus, ACPA-positivity can be considered a specific risk factor for systemic and periarticular bone loss. Through the inhibition of the RANK-RANKL system, denosumab is the only antiresorptive drug currently available that exhibits both a systemic anti-osteoporotic activity and a disease-modifying effect when combined with conventional synthetic or biologic disease-modifying anti-rheumatic drugs (DMARDs). Thus, the combination of DMARD and anti-RANKL therapy could be beneficial in the prevention of fragility fractures and structural damage in the subset of RA patients at risk of radiographic progression, as in the presence of ACPAs.

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.

Adult-onset Still's disease with elderly onset: results from a multicentre study.

OBJECTIVES: In this study, we aimed at describing the clinical characteristics, life-threatening complications occurrence, and mortality of adult-onset Still's disease (AOSD) patients with elderly onset. METHODS: A multicentre retrospective study of prospectively followed-up AOSD patients included in Gruppo Italiano di Ricerca in Reumatologia Clinica e Sperimentale (GIRRCS) cohort was performed. RESULTS: Out of 221 assessed patients, 37 (16.7%) had an onset of the disease aged over 60 years. When compared with younger patients, these were characterised by a higher prevalence of pericarditis (p=0.008), comorbidities (p<0.0001), and mortality (p=0.023). Age predicted the presence of serositis in both univariate (HR: 1.02, 95%CI: 1.01-1.03, p=0.007) and multivariate analyses (HR: 1.02, 95%CI: 1.01-1.04, p=0.007). Age was also a significant predictor of parenchymal lung disease in both univariate (HR: 1.03, 95%CI: 1.01-1.05, p=0.017) and multivariate analyses (HR: 1.03, 95%CI: 1.00-1.05, p=0.048). Furthermore, age resulted to be a negative predictor of polycyclic pattern only in univariate analysis (HR: 0.99, 95%CI: 0.97-1.00, p=0.048). Finally, age significantly predicted the mortality in both univariate (HR: 1.03, 95%CI: 1.00-1.06, p=0.034) and multivariate analyses (HR: 1.05, 95%CI: 1.01-1.08, p=0.012). CONCLUSIONS: Clinical features of AOSD patients in the elderly were described in our cohort. Although the main clinical characteristics were similar comparing older and younger patients, patients aged over 60 years at disease onset were characterised by an increased prevalence of serositis, comorbidities, mostly cardiometabolic, and a higher mortality rate. Age predicted the presence of parenchymal lung disease and mortality, and it could be considered a negative prognostic factor in AOSD.

Cytokine profile, ferritin and multi-visceral involvement characterize macrophage activation syndrome during adult-onset Still's disease.

OBJECTIVES: To multidimensionally characterize macrophage activation syndrome (MAS) complicating adult-onset Still's disease (AOSD) considering cytokine profile, inflammatory markers and multi-visceral involvement of the disease. To perform a high-dimensional phenotypic analysis of circulating immune cells in AOSD patients with and without MAS. To assess interferon (IFN)-related pathways in AOSD synovial tissues by a bulky RNA sequencing. METHODS: Clinical and biologic data were collected and compared in AOSD patients with and without MAS. Sera biomolecules were analysed by Luminex multiplexing technology. Mass cytometry (CyTOF) was used to characterize circulating immune cells. A bulky RNA sequencing was performed in AOSD synovial tissues. RESULTS: Forty consecutive AOSD patients were assessed, 14 complicated with MAS. Paralleling with increases of systemic score and ferritin, MAS patients showed higher levels of IL-1α, IL-1ß, IL-1Ra, IL-2Ra, IL-6, IL-10, IL-17A, IFN-γ, G-CSF, MCP-1, MIP-1α and SCF. Combining the discriminatory ability of these data in identifying MAS, the best model was composed by systemic score, ferritin, IFN-γ and IL-10. By CyTOF analysis, MAS patients showed an increase of circulating 'classical monocytes' and a reduction of total NK cells. Our assessment showed 3477 IFN-related genes (IRGs) were differently expressed in AOSD synovial tissues. CONCLUSIONS: A multidimensional characterization of AOSD patients suggested that IFN-γ, IL-10, ferritin and systemic score discriminated the occurrence of cytokine storm syndrome associated with MAS. The inflammatory milieu of AOSD and MAS may be related to a signature of circulating immune cells. Finally, our results about IRGs reinforced the role of IFN-γ in these patients.