Search

ObjectivesRheumatic immune-related adverse events (irAE) such as (poly)arthritis in patients undergoing immune checkpoint inhibitor (ICI) treatment pose a major clinical challenge. ICI therapy improves CD8+T cell (CD8) function, but CD8 contributes to chronic inflammation in autoimmune arthritis (AA). Thus, we investigated whether immune functional and metabolic changes in CD8 explain the development of musculoskeletal irAE in ICI-treated patients.MethodsPeripheral CD8 obtained from ICI-treated patients with and without arthritis irAEs and from AA patients with and without a history of malignancy were stimulated in media containing13C-labelled glucose with and without tofacitinib or infliximab. Changes in metabolism, immune-mediator release, expression of effector cell-surface molecules and inhibition of tumour cell growth were quantified.ResultsCD8 from patients with irAE showed significantly lower frequency and expression of cell-surface molecule characteristic for activation, effector-functions, homing, exhaustion and apoptosis and reduced release of cytotoxic and proinflammatory immune mediators compared with CD8 from ICI patients who did not develop irAE. This was accompanied by a higher glycolytic rate and ATP production. Gene-expression analysis of pre-ICI-treated CD8 revealed several differentially expressed transcripts in patients who later developed arthritis irAEs. In vitro tofacitinib or infliximab treatment did not significantly change the immune-metabolic profile nor the capacity to release cytolytic mediators that inhibit the growth of the human lung cancer cell line H838.ConclusionsOur study shows that CD8 from ICI-treated patients who develop a musculoskeletal irAE has a distinct immune-effector and metabolic profile from those that remain irAE free. This specific irAE profile overlaps with the one observed in CD8 from AA patients and may prove useful for novel therapeutic strategies to manage ICI-induced irAEs.

BackgroundPsoriatic arthritis (PsA) and axial spondyloarthritis (axSpA) show certain overlaps: A subset of patients with PsA can develop axial involvement (axial PsA, axPsA), while a subset of patients with axSpA presents with psoriasis (axSpA+pso). Treatment strategy for axPsA is mostly based on axSpA evidence.ObjectivesTo compare demographic and disease-specific parameters of axPsA and axSpA+pso.MethodsRABBIT-SpA is a prospective longitudinal cohort study. AxPsA was defined based on (1) clinical judgement by rheumatologists; (2) imaging (sacroiliitis according to modified New York criteria in radiographs or signs of active inflammation in MRI or syndesmophytes/ankylosis in radiographs or signs of active inflammation in spine MRI). axSpA was stratified into axSpA+pso and axSpA without pso.ResultsPsoriasis was documented in 181/1428 axSpA patients (13%). Of 1395 PsA patients, 359 (26%) showed axial involvement. 297 patients (21%) fulfilled the clinical definition and 196 (14%) the imaging definition of axial manifestation of PsA. AxSpA+pso differed from axPsA regardless whether clinical or imaging definition was used. axPsA patients were older, more often female and less often HLA-B27+. Peripheral manifestations were more often present in axPsA than in axSpA+pso, whereas uveitis and inflammatory bowel disease were more common in axSpA+pso. Burden of disease (patient global, pain, physician global) was similar among axPsA and axSpA+pso patients.ConclusionsAxPsA differs from axSpA+pso in its clinical manifestations, irrespective of whether axPsA is defined clinically or by imaging. These findings support the hypothesis that axSpA and PsA with axial involvement are distinct entities, so extrapolation of treatment data from randomised controlled trials in axSpA should be performed with caution.

Objectives Recent transcriptome analyses revealed that 15-fold expanded HLA-DR+ CD90+ synovial fibroblasts (SFs) are potential key mediators of inflammation in rheumatoid arthritis (RA). The reasons for the expansion of HLA-DR+ CD90+ SFs are unclear, but genetic signatures indicated a central role of IFNɣ in the generation of this fibroblast subset. In the present study, we investigated the generation of HLA-DR+ CD90+ SFs and their function. We hypothesized that infiltrating leukocytes such as NK cells become activated in situ, provide IFNɣ and thus contribute to the generation of arthritic HLA-DR+ CD90+ SFs. Methods We combined functional assays using primary human materials and focused bioinformatic analyses of mass cytometry and transcriptomics patient datasets. Results We detected enriched and activated FcɣRIIIA(CD16)+ NK cells in synovia from active RA. CD16 recognized immune complexes in synovial fluid, potentially contributing to NK cell activation in RA. In vitro, NK cell-derived IFNɣ induced HLA-DR and an inflammatory, cytokine secreting, HLA-DR+ phenotype in CD90+ SFs. HLA-DR+ CD90+ SFs consecutively activated CD4+ T cells upon receptor crosslinking via superantigens. HLA-DR+ CD90+ SFs also activated CD4+ T cells in absence of superantigens, an effect that was boosted by NK cell-derived IFNɣ and that was four times stronger in RA compared to osteoarthritis. Finally, JAK inhibition prevented HLA-DR induction and blocked pro-inflammatory signals to T cells. Conclusions HLA-DR+ CD90+ SFs are an activation state that can be induced by IFNɣ, likely provided from infiltrating leukocytes such as activated NK cells. The induction of these pro-inflammatory, IL-6 producing and likely antigen-presenting SFs can be targeted by JAK inhibition.

ObjectiveNeutrophils are typically the most abundant leucocyte in arthritic synovial fluid. We sought to understand changes that occur in neutrophils as they migrate from blood to joint.MethodsWe performed RNA sequencing of neutrophils from healthy human blood, arthritic blood and arthritic synovial fluid, comparing transcriptional signatures with those from murine K/BxN serum transfer arthritis. We employed mass cytometry to quantify protein expression and sought to reproduce the synovial fluid phenotype ex vivo in cultured healthy blood neutrophils.ResultsBlood neutrophils from healthy donors and patients with active arthritis showed largely similar transcriptional signatures. By contrast, synovial fluid neutrophils exhibited more than 1600 differentially expressed genes. Gene signatures identified a prominent response to interferon gamma (IFN-γ), as well as to tumour necrosis factor, interleukin-6 and hypoxia, in both humans and mice. Mass cytometry confirmed that healthy and arthritic donor blood neutrophils are largely indistinguishable but revealed a range of neutrophil phenotypes in synovial fluid defined by downregulation of CXCR1 and upregulation of FcγRI, HLA-DR, PD-L1, ICAM-1 and CXCR4. Reproduction of key elements of this signature in cultured blood neutrophils required both IFN-γ and prolonged culture.ConclusionsCirculating neutrophils from patients with arthritis resemble those from healthy controls, but joint fluid cells exhibit a network of changes, conserved across species, that implicate IFN-γ response and ageing as complementary drivers of the synovial fluid neutrophil phenotype.

Summary Background Owing to increasing remission rates, the management of patients with rheumatoid arthritis in sustained remission is of growing interest. The Rheumatoid Arthritis in Ongoing Remission (RETRO) study investigated tapering and withdrawal of disease-modifying antirheumatic drugs (DMARDs) in patients with rheumatoid arthritis in stable remission to test whether remission could be retained without the need to take DMARD therapy despite an absence of symptoms. Methods RETRO was an investigator-initiated, multicentre, prospective, randomised, controlled, open-label, parallel-group phase 3 trial in patients aged at least 18 years with rheumatoid arthritis for at least 12 months before randomisation who were in sustained Disease Activity Score using 28 joints with erythrocyte sedimentation rate (ESR) remission (score ClinicalTrials.gov ( NCT02779114 ). Findings Between May 26, 2010, and May 29, 2018, 303 patients were enrolled and allocated to continue (n=100), taper (n=102), or stop DMARDs (n=101). 282 (93%) of 303 patients were analysed (93 [93%] of 100 for continue, 93 [91%] of 102 for taper, and 96 [95%] of 101 for stop). Remission was maintained at 12 months by 81·2% (95% CI 73·3–90·0) in the continue group, 58·6% (49·2–70·0) in the taper group, and 43·3% (34·6–55·5) in the stop group (p=0·0005 with log-rank test for trend). Hazard ratios for relapse were 3·02 (1·69–5·40; p=0.0003) for the taper group and 4·34 (2·48–7·60; p Interpretation Reducing antirheumatic drugs in patients with rheumatoid arthritis in stable remission is feasible, with maintenance of remission occurring in about half of the patients. Because relapse rates were significantly higher in patients who tapered or stopped antirheumatic drugs than in patients who continued with a 100% dose, such approaches will require tight monitoring of disease activity. However, remission was regained after reintroduction of antirheumatic treatments in most of those who relapsed in this study. These results might help to prevent overtreatment in a substantial number of patients with rheumatoid arthritis. Funding None.

ObjectivesRA CD8+ T-cells (CD8) maintain their effector pro-inflammatory phenotype by changing their metabolism towards aerobic glycolysis. However, their massive energetic and biosynthetic needs may require additional substrates to furnish this high demand. Since systemic alterations in lipid metabolism have been reported in RA patients, we explored the role of fatty acid (FA) metabolism in CD8 to identify potential targets to curb their pro-inflammatory potential.MethodsThe expression of FA metabolism-related genes was analyzed for total and CD8-subsets from RA patients and healthy controls (CNT). Peripheral-blood CD8 were isolated from RA, PsA, SpA patients under different therapies (DMARD, biologicals, JAK-inhibitors) and CNT and were TCR-stimulated with or without FA metabolism inhibitors. We quantified the expression of the main FA transporters, lipid uptake, intracellular content of (un-)saturated FA, cytokine production, activation, proliferation, and capacity to inhibit tumor cell growth.ResultsThe CD8 gene expression profile of FA metabolism-related genes was significantly different between untreated RA patients and CNT. RA patients with a good clinical response after 6 months MTX therapy significantly increased the expression of FA metabolism-related genes. Cell-surface expression of FA transporters FABP4 and GPR84 and FA-uptake was higher in effector and memory CD8 of RA patients than for CNT. In vitro blockade of FA metabolism significantly impaired CD8 effector functions.ConclusionsRA CD8 present an altered FA-metabolism which can be potential therapeutic targets to control their pro-inflammatory profile, especially by targeting the transport and oxidation of free FAs which are abundant in the serum and synovial fluid of patients.

PurposeHeterozygous mutations in CTLA4 lead to an inborn error of immunity characterized by immune dysregulation and immunodeficiency, known as CTLA-4 insufficiency. Cohort studies on CTLA4 mutation carriers showed a reduced penetrance (around 70%) and variable disease expressivity, suggesting the presence of modifying factors. It is well studied that infections can trigger autoimmunity in humans, especially in combination with a genetic predisposition.MethodsTo investigate whether specific infections or the presence of specific persisting pathogens are associated with disease onset or severity in CTLA-4 insufficiency, we have examined the humoral immune response in 13 CTLA4 mutation carriers, seven without clinical manifestation and six with autoimmune manifestations, but without immunoglobulin replacement therapy against cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus 1/2 (HSV 1/2), parvovirus B19 and Toxoplasma gondii. Additionally, we have measured FcγRIII/CD16A activation by EBV-specific IgG antibodies to examine the functional capabilities of immunoglobulins produced by CTLA4 mutation carriers.ResultsThe seroprevalence between affected and unaffected CTLA4 mutation carriers did not differ significantly for the examined pathogens. Additionally, we show here that CTLA4 mutation carriers produce EBV-specific IgG, which are unimpaired in activating FcγRIII/CD16A.ConclusionsOur results show that the investigated pathogens are very unlikely to trigger the disease onset in CTLA-4-insufficient individuals, and their prevalence is not correlated with disease severity or expressivity.

An imbalance between CD4+-regulatory T-cells (Tregs) and CD4+-responder T-cells (Tresps) correlates with active disease flares in systemic lupus erythematosus (SLE) patients. Both cell subsets consist of highly proliferating Tregs/Tresps expressing inducible T-cell co-stimulatory molecule (ICOS) and less proliferating ICOS--Tregs/Tresps.Six-colour-flow-cytometric analysis was used to examine the effect of ICOS+- and ICOS--Treg/Tresp cell differentiation on the composition of the total CD4+-T-helper cell pool with ICOS+- and ICOS--Tregs/Tresps. Functionality of Tregs was examined using suppression assays.In 83 healthy volunteers, the ratio of ICOS+-Tregs/ICOS+-Tresps increased significantly with age, while that of ICOS--Tregs/ICOS--Tresps did not change. In 86 SLE patients (SLEDAI7), disease activity was associated with an age-independently increased ratio of both ICOS+-Tregs/ICOS+-Tresps and ICOS--Tregs/ICOS--Tresps. In these patients, the functional activity of ICOS+-Tregs, but not of ICOS--Tregs, was preserved. In 13 markedly active disease patients (SLEDAI7), the percentage of both ICOS+-Tregs and ICOS+-Tresps, was strongly increased within total CD4+-T-helper cells. However, the increased ratio of ICOS+-Tregs/ICOS+-Tresps was not maintained in these patients, due to terminal differentiation and accumulation of naïve cells within total ICOS+-Tregs. Despite increased differentiation of both ICOS--Tregs and ICOS--Tresps, the percentage of ICOS--Tregs increased within CD4+-T-helper cells, while that of ICOS--Tresps decreased, resulting in a significantly increased ratio of ICOS--Tregs/ICOS--Tresps independent of age.Our data reveal a crucial role of Treg immune senescence for the occurrence of disease flares in SLE patients, with ICOS+-Treg cells being most affected.

ObjectiveTo analyse the clinical profile of SARS-CoV-2 breakthrough infections in at least double-vaccinated patients with inflammatory rheumatic diseases (IRDs).MethodsData from the physician-reported German COVID-19-IRD registry collected between February 2021 and July 2022 were analysed. SARS-CoV-2 cases were stratified according to patients’ vaccination status as being not vaccinated, double-vaccinated or triple-vaccinated prior to SARS-CoV-2 infection and descriptively compared. Independent associations between demographic and disease features and outcome of breakthrough infections were estimated by multivariable logistic regression.ResultsIn total, 2314 cases were included in the analysis (unvaccinated n=923, double-vaccinated n=551, triple-vaccinated n=803, quadruple-vaccinated n=37). SARS-CoV-2 infections occurred after a median of 151 (range 14–347) days in patients being double-vaccinated, and after 88 (range 14–270) days in those with a third vaccination. Hospitalisation was required in 15% of unvaccinated, 8% of double-vaccinated and 3% of triple-vaccinated/quadruple-vaccinated patients (pConclusionsOur cross-sectional data of COVID-19 infections in patients with IRD showed a significant reduction of hospitalisation due to infection in double-vaccinated or triple-vaccinated patients compared with those without vaccination and even a significant reduction of COVID-19-related deaths in triple-vaccinated patients. These data strongly support the beneficial effect of COVID-19 vaccination in patients with IRD.Trial registration numberEuDRACT 2020-001958-21.

ObjectivesTo analyse whether reported fatigue, one of the most challenging manifestations of systemic lupus erythematosus (SLE), may bias the assessment of disease activity in SLE according to the Physician Global Assessment (PGA).MethodsPatients from the Lupus BioBank of the upper Rhein database, a cross-sectional multicentre collection of detailed clinical and biological data from patients with SLE, were included. Patients had to fulfil the 1997 American College of Rheumatology criteria for SLE and the PGA (0–3 scale) at the time of inclusion had to be available. Fatigue was assessed according to the Fatigue Scale for Motor and Cognitive Functions. Univariate and multivariate regression models were built to determine which variables were associated with the PGA.ResultsA total of 350 patients (89% female; median age: 42 years, IQR: 34–52) were included. The median Safety of Estrogens in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) score was 4 (IQR: 2–6). Of these 350 patients, 257 (73%) reported significant fatigue. The PGA (p=0.004) but not the SELENA-SLEDAI (p=0.43) was significantly associated with fatigue. Both fatigue and SELENA-SLEDAI were independently associated with the PGA in two different multivariate models.ConclusionFatigue is independently associated with disease activity assessed using the PGA but not the SLEDAI. These findings highlight the fact that the PGA should capture only objectively active disease manifestations in order to improve its reliability.

BackgroundIn this study, we investigated the impact of the new haemodynamic definition of pulmonary arterial hypertension (PAH) as proposed by the 6th PH World Symposium on phenotypes and survival in patients with systemic sclerosis (SSc).MethodsIn SSc patients who were prospectively and consecutively screened for PAH including right heart catheterisation in Heidelberg or Zurich, haemodynamic and clinical variables have been reassessed according to the new PAH definition. Patients have been followed for 3.7±3.7 (median 3.4) years; Kaplan-Meier survival analysis was performed. Patients with significant lung or left heart disease were excluded from comparative analyses.ResultsThe final dataset included 284 SSc patients, 146 patients (49.2%) had mean pulmonary arterial pressure (mPAP) ≤20 mm Hg, 19.3% had mPAP 21–24 mm Hg and 29.4% had mPAP ≥25 mm Hg. In the group of mildly elevated mPAP, only four patients (1.4% of the whole SSc cohort) had pulmonary vascular resistance (PVR) values ≥3 Wood Units (WU) and could be reclassified as manifest SSc-APAH. Twenty-eight (9.8%) patients with mPAP of 21–24 mm Hg and PVR ≥2 WU already presented with early pulmonary vascular disease with decreased 6 min walking distance (6MWD) (pConclusionThe data of this study show that a PVR threshold ≥3 WU is too high to enable an early diagnosis of PAH. A PVR threshold ≥2 WU was already associated with pulmonary vascular disease, significantly reduced survival and would be more appropriate in SSc patients with mild PAH.

IntroductionSeveral risk factors for severe COVID-19 specific for patients with inflammatory rheumatic and musculoskeletal diseases (RMDs) have been identified so far. Evidence regarding the influence of different RMD treatments on outcomes of SARS-CoV-2 infection is still poor.MethodsData from the German COVID-19-RMD registry collected between 30 March 2020 and 9 April 2021 were analysed. Ordinal outcome of COVID-19 severity was defined: (1) not hospitalised, (2) hospitalised/not invasively ventilated and (3) invasively ventilated/deceased. Independent associations between demographic and disease features and outcome of COVID-19 were estimated by multivariable ordinal logistic regression using proportional odds model.Results2274 patients were included. 83 (3.6%) patients died. Age, male sex, cardiovascular disease, hypertension, chronic lung diseases and chronic kidney disease were independently associated with worse outcome of SARS-CoV-2 infection. Compared with rheumatoid arthritis, patients with psoriatic arthritis showed a better outcome. Disease activity and glucocorticoids were associated with worse outcome. Compared with methotrexate (MTX), TNF inhibitors (TNFi) showed a significant association with better outcome of SARS-CoV-2 infection (OR 0.6, 95% CI0.4 to 0.9). Immunosuppressants (mycophenolate mofetil, azathioprine, cyclophosphamide and ciclosporin) (OR 2.2, 95% CI 1.3 to 3.9), Janus kinase inhibitor (JAKi) (OR 1.8, 95% CI 1.1 to 2.7) and rituximab (OR 5.4, 95% CI 3.3 to 8.8) were independently associated with worse outcome.ConclusionGeneral risk factors for severity of COVID-19 play a similar role in patients with RMDs as in the normal population. Influence of disease activity on COVID-19 outcome is of great importance as patients with high disease activity—even without glucocorticoids—have a worse outcome. Patients on TNFi show a better outcome of SARS-CoV-2 infection than patients on MTX. Immunosuppressants, rituximab and JAKi are associated with more severe course.

ObjectivesTo investigate factors associated with severe COVID-19 in people with idiopathic inflammatory myopathy (IIM).MethodsDemographic data, clinical characteristics and COVID-19 outcome severity of adults with IIM were obtained from the COVID-19 Global Rheumatology Alliance physician-reported registry. A 3-point ordinal COVID-19 severity scale was defined: (1) no hospitalisation, (2) hospitalisation (and no death) and (3) death. ORs were estimated using multivariable ordinal logistic regression. Sensitivity analyses were performed using a 4-point ordinal scale: (1) no hospitalisation, (2) hospitalisation with no oxygen (and no death), (3) hospitalisation with oxygen/ventilation (and no death) and 4) death.ResultsOf 348 patients, 48% were not hospitalised, 39% were hospitalised (and did not die) and 13% died. Older age (OR=1.59/decade, 95% CI 1.31 to 1.91), high disease activity (OR=3.50, 95% CI 1.25 to 9.83; vs remission), ≥2 comorbidities (OR=2.63, 95% CI 1.39 to 4.98; vs none), prednisolone-equivalent dose >7.5 mg/day (OR=2.40, 95% CI 1.09 to 5.28; vs no intake) and exposure to rituximab (OR=2.71, 95% CI 1.28 to 5.72; vs conventional synthetic disease-modifying antirheumatic drugs only) were independently associated with severe COVID-19. In addition to these variables, in the sensitivity analyses, male sex (OR range: 1.65–1.83; vs female) was also significantly associated with severe outcomes, while COVID-19 diagnosis after 1 October 2020 (OR range: 0.51–0.59; vs on/before 15 June 2020) was significantly associated with less severe outcomes, but these associations were not significant in the main model (OR=1.57, 95% CI 0.95 to 2.59; and OR=0.61, 95% CI 0.37 to 1.00; respectively).ConclusionsThis is the first large registry data on outcomes of COVID-19 in people with IIM. Older age, male sex, higher comorbidity burden, high disease activity, prednisolone-equivalent dose >7.5 mg/day and rituximab exposure were associated with severe COVID-19. These findings will enable risk stratification and inform management decisions for patients with IIM.

Dysregulations in the differentiation of CD4+-regulatory-T-cells (Tregs) and CD4+-responder-T-cells (Tresps) are involved in the development of active systemic lupus erythematosus (SLE). Three differentiation pathways of highly proliferative inducible costimulatory molecule (ICOS)+- and less proliferative ICOS−-CD45RA+CD31+-recent-thymic-emigrant (RTE)-Tregs/Tresps via CD45RA−CD31+-memory-Tregs/Tresps (CD31+-memory-Tregs/Tresps), their direct proliferation via CD45RA+CD31−-mature naïve (MN)-Tregs/Tresps, and the production and differentiation of resting MN-Tregs/Tresp into CD45RA−CD31−-memory-Tregs/Tresps (CD31−-memory-Tregs/Tresps) were examined in 115 healthy controls, 96 SLE remission patients, and 20 active disease patients using six color flow cytometric analysis. In healthy controls an appropriate sequence of these pathways ensured regular age-dependent differentiation. In SLE patients, an age-independently exaggerated differentiation was observed for all Treg/Tresp subsets, where the increased conversion of resting MN-Tregs/Tresps particularly guaranteed the significantly increased ratios of ICOS+-Tregs/ICOS+-Tresps and ICOS−-Tregs/ICOS−-Tresps during remission. Changes in the differentiation of resting ICOS+-MN-Tresps and ICOS−-MN-Tregs from conversion to proliferation caused a significant shift in the ratio of ICOS+-Tregs/ICOS+-Tresps in favor of ICOS+-Tresps and a further increase in the ratio of ICOS−-Tregs/ICOS−-Tresps with active disease. The differentiation of ICOS+-RTE-Tregs/Tresps seems to be crucial for keeping patients in remission, where their limited production of proliferating resting MN-Tregs may be responsible for the occurrence of active disease flares.

Findings from recent transcriptome analyses of the synovium of patients with rheumatoid arthritis (RA) have revealed that 15-fold expanded HLA-DR+CD90+ synovial fibroblasts potentially act as key mediators of inflammation. The reasons for the expansion of HLA-DR+CD90+ synovial fibroblasts are unclear, but genetic signatures indicate that interferon-γ (IFNγ) plays a central role in the generation of this fibroblast subset. The present study was undertaken to investigate the generation, function and therapeutically intended blockage of HLA-DR+CD90+ synovial fibroblasts.We combined functional assays using primary human materials and focused bioinformatic analyses of mass cytometry and transcriptomics patient data sets.We detected enriched and activated Fcγ receptor type IIIa-positive (CD16+) NK cells in the synovial tissue from patients with active RA. Soluble immune complexes were recognized by CD16 in a newly described reporter cell model, a mechanism that could be contributing to the activation of natural killer (NK) cells in RA. In vitro, NK cell-derived IFNγ induced HLA-DR on CD90+ synovial fibroblasts, leading to an inflammatory, cytokine-secreting HLA-DR+CD90+ phenotype. HLA-DR+CD90+ synovial fibroblasts consecutively activated CD4+ T cells upon receptor crosslinking via superantigens. HLA-DR+CD90+ synovial fibroblasts also activated CD4+ T cells in the absence of superantigens, an effect that was initiated by NK cell-derived IFNγ and that was 4 times stronger in patients with RA compared to patients with osteoarthritis. Finally, JAK inhibition in synovial fibroblasts prevented HLA-DR induction and blocked proinflammatory signals to T cells.The HLA-DR+CD90+ phenotype represents an activation state of synovial fibroblasts during the process of inflammation in RA that can be induced by IFNγ, likely generated from infiltrating leukocytes such as activated NK cells. The induction of these proinflammatory, interleukin-6-producing, and likely antigen-presenting synovial fibroblasts can be targeted by JAK inhibition.

© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ., Objectives: To determine factors associated with COVID-19-related death in people with rheumatic diseases. Methods: Physician-reported registry of adults with rheumatic disease and confirmed or presumptive COVID-19 (from 24 March to 1 July 2020). The primary outcome was COVID-19-related death. Age, sex, smoking status, comorbidities, rheumatic disease diagnosis, disease activity and medications were included as covariates in multivariable logistic regression models. Analyses were further stratified according to rheumatic disease category. Results: Of 3729 patients (mean age 57 years, 68% female), 390 (10.5%) died. Independent factors associated with COVID-19-related death were age (66-75 years: OR 3.00, 95% CI 2.13 to 4.22; >75 years: 6.18, 4.47 to 8.53; both vs ≤65 years), male sex (1.46, 1.11 to 1.91), hypertension combined with cardiovascular disease (1.89, 1.31 to 2.73), chronic lung disease (1.68, 1.26 to 2.25) and prednisolone-equivalent dosage >10 mg/day (1.69, 1.18 to 2.41; vs no glucocorticoid intake). Moderate/high disease activity (vs remission/low disease activity) was associated with higher odds of death (1.87, 1.27 to 2.77). Rituximab (4.04, 2.32 to 7.03), sulfasalazine (3.60, 1.66 to 7.78), immunosuppressants (azathioprine, cyclophosphamide, ciclosporin, mycophenolate or tacrolimus: 2.22, 1.43 to 3.46) and not receiving any disease-modifying anti-rheumatic drug (DMARD) (2.11, 1.48 to 3.01) were associated with higher odds of death, compared with methotrexate monotherapy. Other synthetic/biological DMARDs were not associated with COVID-19-related death. Conclusion: Among people with rheumatic disease, COVID-19-related death was associated with known general factors (older age, male sex and specific comorbidities) and disease-specific factors (disease activity and specific medications). The association with moderate/high disease activity highlights the importance of adequate disease control with DMARDs, preferably without increasing glucocorticoid dosages. Caution may be required with rituximab, sulfasalazine and some immunosuppressants.

Objective This prospective study was undertaken to evaluate right ventricular function and pulmonary arterial compliance (PAC; ratio of stroke volume to pulse pressure) at rest and during exercise in patients with systemic sclerosis (SSc) with normal mean pulmonary artery pressure (PAP), patients with SSc with mildly elevated mean PAP, and patients with SSc with manifest pulmonary hypertension (PH). Methods Patients with SSc (n = 112) underwent clinical assessment and right-sided heart catheterization at rest and during exercise and were divided into 3 groups according to their resting mean PAP values: normal mean PAP (≤20 mm Hg), mildly elevated mean PAP (21-24 mm Hg), and PH (mean PAP ≥25 mm Hg). Results were compared between groups by analysis of variance followed by post hoc Student's t-test. Results Compared to patients with normal mean PAP, patients with mildly elevated mean PAP had a lower 6-minute walking distance (P = 0.008), lower cardiac index (P = 0.027) and higher pulmonary vascular resistance (P = 0.0002) during exercise, and lower PAC at rest (P = 0.016) and different stages of exercise (P = 0.033 for 25W and P = 0.024 for 75W). Conclusion The results of this study suggest that impaired 6-minute walking distance in SSc patients with mildly elevated mean PAP might be caused by reduced PAC during exercise and reduced right ventricular output reserve, presumably due to impaired coupling between the right ventricle and the pulmonary vasculature. These findings provide further evidence of the clinical relevance of mildly elevated mean PAP in patients with SSc.

To evaluate risk factors associated with unfavourable outcomes: emergency care, hospitalisation, admission to intensive care unit (ICU), mechanical ventilation and death in patients with immune-mediated rheumatic disease (IMRD) and COVID-19.Analysis of the first 8 weeks of observational multicentre prospective cohort study (ReumaCoV Brasil register). Patients with IMRD and COVID-19 according to the Ministry of Health criteria were classified as eligible for the study.334 participants were enrolled, a majority of them women, with a median age of 45 years; systemic lupus erythematosus (32.9%) was the most frequent IMRD. Emergency care was required in 160 patients, 33.0% were hospitalised, 15.0% were admitted to the ICU and 10.5% underwent mechanical ventilation; 28 patients (8.4%) died. In the multivariate adjustment model for emergency care, diabetes (prevalence ratio, PR 1.38; 95% CI 1.11 to 1.73; p=0.004), kidney disease (PR 1.36; 95% CI 1.05 to 1.77; p=0.020), oral glucocorticoids (GC) (PR 1.49; 95% CI 1.21 to 1.85; p0.001) and pulse therapy with methylprednisolone (PR 1.38; 95% CI 1.14 to 1.67; p=0.001) remained significant; for hospitalisation, age50 years (PR 1.89; 95% CI 1.26 to 2.85; p=0.002), no use of tumour necrosis factor inhibitor (TNFi) (PR 2.51;95% CI 1.16 to 5.45; p=0.004) and methylprednisolone pulse therapy (PR 2.50; 95% CI 1.59 to 3.92; p0.001); for ICU admission, oral GC (PR 2.24; 95% CI 1.36 to 3.71; p0.001) and pulse therapy with methylprednisolone (PR 1.65; 95% CI 1.00 to 2.68; p0.043); the two variables associated with death were pulse therapy with methylprednisolone or cyclophosphamide (PR 2.86; 95% CI 1.59 to 5.14; p0.018).Age50 years and immunosuppression with GC and cyclophosphamide were associated with unfavourable outcomes of COVID-19. Treatment with TNFi may have been protective, perhaps leading to the COVID-19 inflammatory process.

The overall clinical outcome of inflammatory conditions is the result of the balance between pro-inflammatory and anti-inflammatory mediators. Because nuclear factor kappa B (NF-ĸB) is at the bottom of many inflammatory conditions, methods to evaluate the net effect of inflammation modulators on this master regulator have been conceptualized for years.Using an ex vivo NF-ĸB reporter cell line-based assay, plasma samples of patients with rheumatoid arthritis (n = 27), psoriasis (n = 15), or severe coronavirus disease-19 (COVID-19) (n = 21) were investigated for NF-ĸB activation compared to plasma samples from 9 healthy volunteers.When separated by C-reactive protein (CRP) threshold levels, samples of patients exhibiting increased CRP levels (≥5 mg/l) activated NF-ĸB more efficiently than samples from patients with levels below 5 mg/l (P = 0.0001) or healthy controls (P = 0.04). Overall, there was a moderate association of CRP levels with NF-ĸB activation (Spearman r = 0.66; p 0.0001). Plasma from COVID-19 patients activated NF-ĸB more efficiently (mean 2.4-fold compared to untreated reporter cells) than samples from any other condition (healthy controls, 1.8-fold, P = 0.0025; rheumatoid arthritis, 1.7-fold, P 0.0001; psoriasis, 1.7-fold, P 0.0001). In contrast, effects of rheumatoid arthritis, psoriasis, or healthy volunteer samples did not differ.This study shows that a NF-ĸB reporter cell line can be used to evaluate the net inflammatory effect of clinical plasma samples. Patients with chronic but stable rheumatoid arthritis or psoriasis do not exhibit increased plasma levels of NF-ĸB-activating compounds as opposed to COVID-19 patients with high inflammatory burden.

IntroductionWhether patients with inflammatory rheumatic and musculoskeletal diseases (RMD) are at higher risk to develop severe courses of COVID-19 has not been fully elucidated. Aim of this analysis was to describe patients with RMD according to their COVID-19 severity and to identify risk factors for hospitalisation.MethodsPatients with RMD with PCR confirmed SARS-CoV-2 infection reported to the German COVID-19 registry from 30 March to 1 November 2020 were evaluated. Multivariable logistic regression was used to estimate ORs for hospitalisation due to COVID-19.ResultsData from 468 patients with RMD with SARS-CoV-2 infection were reported. Most frequent diagnosis was rheumatoid arthritis, RA (48%). 29% of the patients were hospitalised, 5.5% needed ventilation. 19 patients died. Multivariable analysis showed that age >65 years (OR 2.24; 95% CI 1.12 to 4.47), but even more>75 years (OR 3.94; 95% CI 1.86 to 8.32), cardiovascular disease (CVD; OR 3.36; 95% CI 1.5 to 7.55), interstitial lung disease/chronic obstructive pulmonary disease (ILD/COPD) (OR 2.79; 95% CI 1.2 to 6.49), chronic kidney disease (OR 2.96; 95% CI 1.16 to 7.5), moderate/high RMD disease activity (OR 1.96; 95% CI 1.02 to 3.76) and treatment with glucocorticoids (GCs) in dosages >5 mg/day (OR 3.67; 95% CI 1.49 to 9.05) were associated with higher odds of hospitalisation. Spondyloarthritis patients showed a smaller risk of hospitalisation compared with RA (OR 0.46; 95% CI 0.23 to 0.91).ConclusionAge was a major risk factor for hospitalisation as well as comorbidities such as CVD, ILD/COPD, chronic kidney disease and current or prior treatment with GCs. Moderate to high RMD disease activity was also an independent risk factor for hospitalisation, underlining the importance of continuing adequate RMD treatment during the pandemic.

IntroductionAnti-glomerular basement membrane (GBM) antibodies are pathogenic antibodies first detected in renal-limited anti-GBM disease and in Goodpasture disease, the latter characterized by rapidly progressive crescentic glomerulonephritis combined with intra-alveolar hemorrhage. Studies have suggested that anti-GBM antibody positivity may be of interest in lupus nephritis (LN). Moreover, severe anti-GBM vasculitis cases in patients with systemic lupus erythematosus (SLE) have been described in the literature, but few studies have assessed the incidence of anti-GBM antibodies in SLE patients.ObjectiveThe main study objective was to determine if positive anti-GBM antibodies were present in the serum of SLE patients with or withoutproliferativerenal damage and compared to a healthy control group.MethodologyThis retrospective study was performed on SLE patients’ sera from a Franco-German European biobank, developed between 2011 and 2014, from 17 hospital centers in the Haut-Rhin region. Patients were selected according to their renal involvement, and matched by age and gender. The serum from healthy voluntary blood donors was also tested. Anti-GBM were screened by fluorescence enzyme immunoassay (FEIA), and then by indirect immunofluorescence (IIF) in case of low reactivity detection (titer >6 U/ml).ResultsThe cohort was composed of 100 SLE patients withproliferativeLN (27% with class III, 67% with class IV, and 6% with class V), compared to 100 SLE patients without LN and 100 controls. Patients were mostly Caucasian and met the ACR 1997 criteria and/or the SLICC 2012 criteria. Among the 300 tested sera, no significant levels of anti-GBM antibodies were detected (>10 U/ml) by the automated technique, three sera were found “ambivalent” (>7 U/ml): one in the SLE with LN group and two in the SLE without LN group. Subsequent IIF assays did not detect anti-GBM antibodies.ConclusionAnti-GBM antibodies were not detected in the serum of Caucasian patients with SLE, even in case of renal involvement, a situation favoring the antigenic exposure of glomerular basement membranes. Our results reaffirm the central role of anti-GBM antibodies as a specific diagnostic biomarker for Goodpasture vasculitis and therefore confirm that anti-GBM antibody must not be carried out in patients with SLE (with or without LN) in the absence of disease-suggestive symptoms.

The significance of inflammatory rheumatic diseases (IRDs) and their therapies for the risk of patients with respect to SARS-CoV-2 infection and the course of COVID-19 is still not fully understood. In particular, it is not completely clear whether IRDs, their therapies or other factors in patients with IRDs pose a risk to patients and what consequences should be drawn to protect patients with IRDs. In their manuscript, Nunez et al 1 describe that in a real-world-setting SARS-CoV-2-infected patients with IRDs often require hospitalisation. Important in their observation is that this was associated with systemic autoimmune conditions (as opposed to well-controlled chronic inflammatory arthritis) and related to risk factors known also for the non-rheumatic population, such as advanced age or comorbidities, but not with the immunomodulating, antirheumatic therapy. These data are reassuring, as they underline once again that well-controlled IRDs per se do not pose a risk of contracting SARS-CoV-2 nor do ongoing immunomodulating therapies pose a threat for patients with IRD.2–5 Therefore, in order to avoid reactivation of an underlying IRD and to prevent the risk of increased susceptibility to infection and a possibly necessary administration of glucocorticoids to control immunological activity, several professional societies have advocated in their recommendations for the management of patients with IRDs in times of SARS-CoV-2/COVID-19 the continuation of therapy with anti-inflammatory drugs, provided that clinical symptoms of COVID-19 do not develop.6–8 On the other hand, these guidelines also recommend strict adherence to the hygiene and distance measures to reduce the risk of exposure to the virus. In this respect, several recent comparative surveys of patients with IRDs and the non-rheumatic population have shown that patients with IRDs do not actually have a different risk of infection than the general …

ObjectivesPatients with inflammatory rheumatic diseases (IRD) infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be at risk to develop a severe course of COVID-19. The influence of immunomodulating drugs on the course of COVID-19 is unknown. To gather knowledge about SARS-CoV-2 infections in patients with IRD, we established a registry shortly after the beginning of the pandemic in Germany.MethodsUsing an online questionnaire (www.COVID19-rheuma.de), a nationwide database was launched on 30 March 2020, with appropriate ethical and data protection approval to collect data of patients with IRD infected with SARS-CoV-2. In this registry, key clinical and epidemiological parameters—for example, diagnosis of IRD, antirheumatic therapies, comorbidities and course of the infection—are documented.ResultsUntil 25 April 2020, data from 104 patients with IRD infected with SARS-CoV-2 were reported (40 males; 63 females; 1 diverse). Most of them (45%) were diagnosed with rheumatoid arthritis, 59% had one or more comorbidities and 42% were treated with biological disease-modifying antirheumatic drugs. Hospitalisation was reported in 32% of the patients. Two-thirds of the patients already recovered. Unfortunately, 6 patients had a fatal course.ConclusionsIn a short time, a national registry for SARS-CoV2-infected patients with IRD was established. Within 4 weeks, 104 cases were documented. The registry enables to generate data rapidly in this emerging situation and to gain a better understanding of the course of SARS-CoV2-infection in patients with IRD, with a distinct focus on their immunomodulatory therapies. This knowledge is valuable for timely information of physicians and patients with IRD, and shall also serve for the development of guidance for the management of patients with IRD during this pandemic.

In their correspondence Iudici et al 1 highlight three important aspects which are to consider in the interpretation of survival data when introducing new thresholds of an early stage of disease.2 They point out, that lead-time bias, length-time bias as well as increasing numbers of patients have to be considered for the new haemodynamic definition of pulmonary arterial hypertension (PAH). In studies investigating the effect of systematic PAH screening programmes on survival in patients with systemic sclerosis, part of the effect of an increased survival may be attributed to lead-time bias and length-time bias.3 4 We agree with Iudici et al that lead-time bias is an important aspect when introducing a new definition of a disease, which includes patients at a less severe stage. This becomes especially important for screening programmes, as survival of screened patients who are diagnosed at early disease stages may implicitly be better compared with patients with a more severe disease. In our study we analysed the frequency of PAH in patients with systemic sclerosis when applying the new PAH definition according to the suggestion from the World Symposium on pulmonary hypertension in Nice 2018. According to a large meta-analysis of haemodynamic data of healthy people, a pulmonary vascular resistance (PVR) >2 Wood Units (WU) …

Summary Thorough understanding of the complex pathophysiology of osteoarthritis (OA) is necessary in order to open new avenues for treatment. The aim of this study was to characterize the CD4+ T cell population and evaluate their activation and polarization status in OA joints. Fifty-five patients with end-stage knee OA (Kellgren–Lawrence grades III–IV) who underwent surgery for total knee arthroplasty (TKA) were enrolled into this study. Matched samples of synovial membrane (SM), synovial fluid (SF) and peripheral blood (PB) were analysed for CD3+CD4+CD8– T cell subsets [T helper type 1 (Th1), Th2, Th17, regulatory T cells] and activation status (CD25, CD69, CD45RO, CD45RA, CD62L) by flow cytometry. Subset-specific cytokines were analysed by cytometric bead array (CBA). SM and SF samples showed a distinct infiltration pattern of CD4+ T cells. In comparison to PB, a higher amount of joint-derived T cells was polarized into CD3+CD4+CD8– T cell subsets, with the most significant increase for proinflammatory Th1 cells in SF. CBA analysis revealed significantly increased immunomodulating cytokines [interferon (IFN)-γ, interleukin (IL)-2 and IL-10] in SF compared to PB. Whereas in PB only a small proportion of CD4+ T cells were activated, the majority of joint-derived CD4+ T cells can be characterized as activated effector memory cells (CD69+CD45RO+CD62L–). End-stage OA knees are characterized by an increased CD4+ T cell polarization towards activated Th1 cells and cytokine secretion compared to PB. This local inflammation may contribute to disease aggravation and eventually perpetuate the disease process.

Cell activation and apoptosis lead to the formation of extracellular vesicles (EVs) such as exosomes or microvesicles (MVs). EVs have been shown to modulate immune responses; recently, MVs were described to carry microRNA (miRNA) and a role for MVs in the pathogenesis of autoimmune diseases has been discussed. Here we systematically characterized MVs and exosomes according to their release stimuli. The miRNA content of viable or apoptotic human T lymphocytes and the corresponding MVs was analyzed. miRNA, protein and surface marker expression, as well as cytokine release by human monocytes was measured after EV engulfment. Finally, miRNA expression in T lymphocytes and MVs of healthy individuals was compared with those of systemic lupus erythematosus (SLE) patients. We demonstrate that, depending on the stimuli, distinct subtypes of EVs are released, differing in size and carrying a specific RNA profile. We observed an accumulation of distinct miRNAs in MVs after induction of apoptosis and the transfer of functional miRNA by MVs into human monocytes. MVs released from apoptotic cells provoke less of an inflammatory response than those released from viable cells. MiR-155*, miR-34b and miR-34a levels in T lymphocytes and corresponding MVs were deregulated in SLE when compared to healthy individuals.

Regulatory T cells (Tregs) are critical mediators of immune tolerance, yet their involvement in the autoimmune disease systemic lupus erythematosus (SLE) is incompletely understood. We analyzed CD4+ T cell subpopulations with Treg-related phenotypes and their association with disease activity in peripheral blood (PB) and tissues of patients with SLE. In detail, we quantified subpopulations regarding CD25, FOXP3, CD62L, CCR6, CD27, CD45RA, and CD45RO expression in PB from 31 patients with SLE divided into two disease activity groups and 32 healthy controls using flow cytometry. CD4+ and FOXP3+ T cells in skin and kidney biopsies of patients with SLE were quantified by immunohistochemistry. CD4+CD25+/++FOXP3+ and CD4+CD25+CD45RA-/CD45RO+ T cell frequencies were significantly higher in PB from patients with active compared to inactive SLE. The fraction of CD4+CD25++FOXP3+ Tregs and CD4+CD25+CD45RA+/CD45RO- naive Tregs was not significantly different between these groups. CD4+CD25++ Tregs from active SLE patients comprised significantly less CD27+ cells and more CCR6+ cells compared to patients with inactive SLE. The percentage of CD4+FOXP3+ T cells among inflammatory infiltrates in skin and kidney biopsies of SLE patients was not different from other inflammatory skin/kidney diseases. In conclusion, although CD4+FOXP3+ T cell frequencies in the inflamed tissues of SLE patients were comparable to other inflammatory diseases, distinct T cell subpopulations appeared misbalanced in PB of patients with active SLE. Here, cells phenotypically resembling activated T cells, but not Tregs, were increased compared to patients with inactive SLE. Within Tregs of patients with active SLE, markers related to Treg function and homing were altered.

OBJECTIVE CD8+ T cells contribute to rheumatoid arthritis (RA) by releasing proinflammatory and cytolytic mediators, even in a challenging hypoxic and nutrient-poor microenvironment such as the synovial membrane. This study was undertaken to explore the mechanisms through which CD8+ T cells meet their metabolic demands in the blood and synovial membrane of patients with RA. METHODS Purified blood CD8+ T cells from patients with RA, patients with psoriatic arthritis (PsA), and patients with spondyloarthritis (SpA), as well as healthy control subjects, and CD8+ T cells from RA synovial membrane were stimulated in medium containing 13 C-labeled metabolic substrates in the presence or absence of metabolic inhibitors, under conditions of normoxia or hypoxia. The production of metabolic intermediates was quantified by 1 H-nuclear magnetic resonance. The expression of metabolic enzymes, transcription factors, and immune effector molecules was assessed at both the messenger RNA (mRNA) and protein levels. CD8+ T cell functional studies were performed. RESULTS RA blood CD8+ T cells met their metabolic demands through aerobic glycolysis, production of uniformly 13 C-enriched lactate in the RA blood (2.6 to 3.7-fold higher than in patients with SpA, patients with PsA, and healthy controls; P < 0.01), and induction of glutaminolysis. Overexpression of Warburg effect-linked enzymes in all RA CD8+ T cell subsets maintained this metabolic profile, conferring to the cells the capacity to proliferate under hypoxia and low-glucose conditions. In all RA CD8+ T cell subsets, lactate dehydrogenase A (LDHA) was overexpressed at the mRNA level (P < 0.03 versus controls; n = 6 per group) and protein level (P < 0.05 versus controls; n = 17 RA patients, n = 9 controls). In RA blood, inhibition of LDHA with FX11 led to reductions in lipogenesis, migration and proliferation of CD8+ T cells, and CD8+ T cell effector functions, while production of reactive oxygen species was increased by 1.5-fold (P < 0.03 versus controls). Following inhibition of LDHA with FX11, RA CD8+ T cells lost their capacity to induce healthy B cells to develop a proinflammatory phenotype. Similar metabolic alterations were observed in RA CD8+ T cells from the synovial membrane. CONCLUSION Remodeling glucose and glutamine metabolism in RA CD8+ T cells by targeting LDHA activity can reduce the deleterious inflammatory and cytolytic contributions of these cells to the development of autoimmunity.

Idiopathic acute and recurrent pericarditis are rare diseases of unknown origin. Here, we review trigger factors, pathomechanism, and treatment options for acute and recurrent pericarditis. Acute pericarditis can be triggered by viral infections, myocardial ischemia, heart catheter interventions, cardiac surgery or seem to occur without any trigger. Earlier reports about viral nucleic acids in the effusion or myocardial autoantibodies in serum were detected only in a minority of patients. The current pathomechanistic concept focuses on the innate immune system. Clinical trials revealed that colchicine and anti-IL1β-targeted medication were effective to control acute and recurrent attacks. Activation of the innate immune system in pericarditis suggests that autoinflammation contributes to acute and recurrent pericarditis. The efficacy of colchicine and anti-IL1β-targeted medication in clinical trials indicates that acute and recurrent pericarditis should be regarded as an autoinflammatory disease. Therefore, idiopathic pericarditis should be considered as an autoinflammatory disease.

Background:RA CD8+ T cells (CD8s) have been shown to vastly contribute to tissue damage and RA disease activity by presenting and maintaining an active effector phenotype promoting autoinflammation. In order to meet their high metabolic requirements RA CD8s alter not only their glycolytic and glutaminolytic profiles, but also rely on increased lipid metabolism characterized by increased free fatty acid (FFA) uptake and lipid biosynthesis.Objectives:In order to classify the importance of lipid metabolism in RA CD8s in terms of initiation and perpetuation of effector functions and therefore exploring potential novel therapy targeting points or biomarkers additional investigations have to been made. By analysing FFA uptake and the expression of free fatty acid transporters (FAT) upon TCR-stimulation in RA, PsA, SpA patients and healthy controls (HC), we aimed to further characterize the importance of RA CD8s´ lipid metabolism.Methods:Blood samples from 23 RA patients, 22 SpA patients, 20 PsA patients and 7 HC recruited at Heidelberg University Hospital were processed via negative magnetic separation selection to obtain purified CD8s. CD8s were cultured for 72 hours in [1,6-13C] glucose containing medium in the presence of anti-CD3 and anti-CD28. FFA uptake was measured by Palmitate-Bodipy 488 staining (ThermoFisher), the expression of FAT CD36, FABP4 and GPR84 besides CD69, CD36, CD45RA, CD3 and CD8 were assessed by FACS analysis.Ethic approval NR: S-096/2016.Results:The intake of the FFA palmitate by CD8s was higher in all patients groups than in HC (p < 0,05). In all three diseases´ stimulated CD8s, unlike in the HC group, the expression of GPR84 was inversely correlating to the expression of CD69 (Spearman r < -0,62). In patient´s stimulated CD8s the expression of GPR84 tended to be lower in RA and PSA effector memory (EM) CD8s. In RA and HC the expression of FABP4 tended to be lower in the naive CD8+ subset when compared to the effector subset. HC naive and effector CD8+ subsets had a higher expression of CD36 than in the patient groups. In RA and SPA patients the expression of FAT correlated with clinical variables. In RA DAS28 and CRP inversely correlated with CD36 (MFI), and disease duration with FABP4 as well. In SPA CRP and BASDAI inversely correlated with FABP4 while disease duration had a negative correlation with CD36 (MFI). GPR84 (MFI) had an inverted relationship to BASDAI. While the BMI was directly correlated with the expression of CD36 in RA, this relationship was inverted in SPA.Conclusion:A high free fatty acid uptake seems to characterize autoimmune arthritis CD8+ T cells. The gain of effector functions appears to be connected to changes in the expression of different fatty acid transporters on the surface of CD8+ T cells. The correlation between the expression of fatty acid transporters and clinical parameters (specially disease activity scores) in RA and SPA suggests that they could potentially be used as biomarkers for disease activity and progression.Acknowledgements:We thank all the individuals involved in the study for their participation.Disclosure of Interests:None declared

Background CD4+ T cells are of great importance in the pathogenesis of systemic lupus erythematosus (SLE), as an imbalance between CD4+ regulatory T cells (Tregs) and CD4+ responder T cells (Tresps) causes flares of active disease in SLE patients. In this study, we aimed to find the role of aberrant Treg/Tresp cell differentiation for maintaining Treg/Tresp cell balance and Treg functionality. Methods To determine differences in the differentiation of Tregs/Tresps we calculated the percentages of CD45RA+CD31+ recent thymic emigrant (RTE) Tregs/Tresps and CD45RA+CD31− mature naive (MN) Tregs/Tresps, as well as CD45RA−CD31+ and CD45RA−CD31− memory Tregs/Tresps (CD31+ and CD31− memory Tregs/Tresps) within the total Treg/Tresp pool of 78 SLE remission patients compared with 94 healthy controls of different ages. The proliferation capacity of each Treg/Tresp subset was determined by staining the cells with anti-Ki67 monoclonal antibodies. Differences in the autologous or allogeneic Treg function between SLE remission patients and healthy controls were determined using suppression assays. Results With age, we found an increased differentiation of RTE Tregs via CD31+ memory Tregs and of RTE Tresps via MN Tresps into CD31− memory Tregs/Tresp in healthy volunteers. This opposite differentiation of RTE Tregs and Tresps was associated with an age-dependent increase in the suppressive activity of both naive and memory Tregs. SLE patients showed similar age-dependent Treg cell differentiation. However, in these patients RTE Tresps differentiated increasingly via CD31+ memory Tresps, whereby CD31− memory Tresps arose that were much more difficult to inhibit for Tregs than those that emerged through differentiation via MN Tresps. Consequently, the increase in the suppressive activity of Tregs with age could not be maintained in SLE patients. Testing the Tregs of healthy volunteers and SLE patients with autologous and nonautologous Tresps revealed that the significantly decreased Treg function in SLE patients was not exclusively attributed to an age-dependent diminished sensitivity of the Tresps for Treg suppression. The immunosuppressive therapy reduced the accelerated age-dependent Tresp cell proliferation to normal levels, but simultaneously inhibited Treg cell proliferation below normal levels. Conclusions Our data reveal that the currently used immunosuppressive therapy has a favorable effect on the differentiation and proliferation of Tresps but has a rather unfavorable effect on the proliferation of Tregs. Newer substances with more specific effects on the immune system would be desirable. Electronic supplementary material The online version of this article (10.1186/s13075-018-1778-6) contains supplementary material, which is available to authorized users.

Item does not contain fulltext BACKGROUND: Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a negative immune regulator. Heterozygous CTLA4 germline mutations can cause a complex immune dysregulation syndrome in human subjects. OBJECTIVE: We sought to characterize the penetrance, clinical features, and best treatment options in 133 CTLA4 mutation carriers. METHODS: Genetics, clinical features, laboratory values, and outcomes of treatment options were assessed in a worldwide cohort of CTLA4 mutation carriers. RESULTS: We identified 133 subjects from 54 unrelated families carrying 45 different heterozygous CTLA4 mutations, including 28 previously undescribed mutations. Ninety mutation carriers were considered affected, suggesting a clinical penetrance of at least 67%; median age of onset was 11 years, and the mortality rate within affected mutation carriers was 16% (n = 15). Main clinical manifestations included hypogammaglobulinemia (84%), lymphoproliferation (73%), autoimmune cytopenia (62%), and respiratory (68%), gastrointestinal (59%), or neurological features (29%). Eight affected mutation carriers had lymphoma, and 3 had gastric cancer. An EBV association was found in 6 patients with malignancies. CTLA4 mutations were associated with lymphopenia and decreased T-, B-, and natural killer (NK) cell counts. Successful targeted therapies included application of CTLA-4 fusion proteins, mechanistic target of rapamycin inhibitors, and hematopoietic stem cell transplantation. EBV reactivation occurred in 2 affected mutation carriers after immunosuppression. CONCLUSIONS: Affected mutation carriers with CTLA-4 insufficiency can present in any medical specialty. Family members should be counseled because disease manifestation can occur as late as 50 years of age. EBV- and cytomegalovirus-associated complications must be closely monitored. Treatment interventions should be coordinated in clinical trials.

Objective.To evaluate patients with psoriatic arthritis (PsA) receiving etanercept (ETN) monotherapy or ETN plus conventional synthetic disease-modifying antirheumatic drugs (csDMARD) to determine the proportion achieving a clinically meaningful response in arthritis, psoriasis, and quality of life simultaneously.Methods.A prospective, multicenter, 52-week observational study in patients with active PsA evaluated treatment with ETN in clinical practice (ClinicalTrials.gov:NCT00293722). This analysis assessed simultaneous achievement of 3 treatment targets: low disease activity (LDA) based on 28-joint count Disease Activity Score (DAS28); body surface area (BSA) involvement ≤ 3%; and a score > 45 on the Medical Outcomes Study Short Form-12 (SF-12) physical component summary.Results.Of 579 patients, 380 received ETN monotherapy and 199 received combination ETN plus csDMARD. At 52 weeks, data for all 3 disease domains were available for 251 patients receiving monotherapy and 151 receiving combination therapy. In the monotherapy and combination therapy groups, 61 (24.3%) and 37 (24.5%) patients, respectively, achieved all 3 treatment targets simultaneously. A significantly greater proportion of patients receiving monotherapy versus combination therapy achieved SF-12 > 45 (43.0% vs 31.8%; p < 0.05) and DAS28 LDA (72.5% vs 62.3%; p < 0.05). Conversely, BSA ≤ 3% was reached by a significantly greater proportion receiving combination therapy (75.5% vs 56.6%; p < 0.001). However, baseline BSA involvement was higher for the monotherapy group.Conclusion.While nearly half the patients achieved arthritis and psoriasis treatment targets simultaneously and one-fourth reached all 3 treatment targets, combining ETN and csDMARD did not substantially improve clinical response compared with ETN monotherapy in this real-world PsA patient population.

Introduction An understanding of real-world predictors of abatacept retention is limited. We analysed retention rates and predictors of abatacept retention in biologic-naïve and biologic-failure patients in a 12-month interim analysis of the 2-yearAbataCepTIn rOutiNe clinical practice (ACTION) study. Methods ACTION was an international, observational study of patients with moderate-to-severe rheumatoid arthritis (RA) who initiated intravenous abatacept. In this 12-month interim analysis, crude abatacept retention rates, predictors of retention and European League Against Rheumatism (EULAR) response were evaluated in both biologic-naïve and biologic-failure patients. Retention by rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) status was also assessed, in patients with or without baseline radiographic erosions, and by body mass index (BMI). Results Overall, 2350/2364 enrolled patients were evaluable (674 biologic naїve; 1676 biologic failure). Baseline characteristics were largely similar in biologic-naïve and biologic-failure groups. Crude retention rates (95% CI) at 12 months were significantly higher in biologic-naїve (78.1%(74.7% to 81.2%)) versus biologic-failure patients (69.9%(67.6% to 72.1%); P

Background Cross-talk between synovial fibroblasts (SF) and immune cells is suggested to play a crucial role in inflammation and chronification of rheumatoid arthritis (RA). The contribution of B cells in this process is poorly defined. Methods Here, primary B cells from healthy donors were polyclonally activated and cocultured with SF of non-synovitic origin from patients with osteoarthritis. Results In B–SF cocultures the concentrations of interleukin 6 (IL-6) and IL-8 increased manifold compared with single cultures even under physical separation and remained stable for several days after B-cell removal. Intracellular staining confirmed SF as key producers of IL-6 and IL-8, and B cells as main producers of tumour necrosis factor alpha (TNFα) and IL-1s. Blocking experiments with a combination of anti-TNFα-antibodies and rIL-1RA significantly reduced SF cytokine production by up to 90%, suggesting that B-cell-derived TNFα and IL-1s were crucial mediators of SF activation. Interestingly, B-cell cytokine production, CD25 expression and proliferation decreased in cocultures by at least 50%, demonstrating a negative regulatory loop towards the activated B cells. Inhibition of activin receptor-like kinase 5, a crucial component of the tumour growth factor s (TGFs) signalling pathway, partly restored B-cell proliferation, suggesting a contribution of SF-derived TGFs in B-cell suppression. Besides cytokines, B-cell-activated SF also upregulated secretion of matrix metalloproteases such as MMP-3, thereby acquiring potential tissue destructive properties. This was confirmed by their invasion into human cartilage in the severe combined immunodeficiency mouse fibroblast invasion model in vivo. Conclusions Interaction with activated B cells leads to conversion of non-arthritic SF into SF with a proinflammatory and aggressive RA-like phenotype, thereby suggesting a new, so far unrecognised role for B cells in RA pathogenesis.

PD-1 antibodies (PD1ab) are increasingly used in metastatic melanoma and other malignancies. Arthralgia is an underestimated side effect of PD-1 antibody treatment with unknown cause. Our aim was to characterize PD1ab-induced arthralgia. We retrospectively included patients with metastatic cutaneous malignancies treated with pembrolizumab or nivolumab ± ipilimumab at the National Center for Tumor Diseases (Heidelberg) between 01/2013 and 09/2016. Arthralgia was characterized by laboratory diagnostics, imaging, and if indicated, rheumatologic consultation. 26 of 195 patients (13.3%) developed arthralgia. The median onset of symptoms was 100 days (7–780 days). Most frequently, arthralgia involved large joints (shoulders, knees) in a predominantly symmetrical pattern. Only two patients were seropositive for rheumatoid factor and/or anti-citrullinated protein antibodies. Ten patients developed the clinical picture of arthritis, with seven of them showing synovitis in MRI or PET/CT. Five patients showed inflammation in joints pre-damaged by osteoarthritis. In 11 patients arthralgia could not be specified. The majority of patients was satisfactorily treated with non-steroidal anti-inflammatory drugs (NSAIDs), 23.1% required additional low-dose corticosteroids and only 7.6% of our patients received further immunosuppressive treatment. Patients with arthralgia showed a better treatment response and improved PFS and OS. Arthralgia is frequent during PD1ab treatment. The clinical picture varies between synovitis of predominantly large joints, progressive osteoarthritis and arthralgia without evident joint damage. Vast majority of cases can be satisfactorily managed by NSAID and/or low-dose corticosteroids.

Background Multipotent mesenchymal stromal cells (MSC) are well known for their multilineage potential and immunosuppressive properties. They might be a useful alternative for treatment of chronic inflammatory diseases. Little is known however, in how far the inflammatory cellular environment eg, activated lymphocytes and their mediators might interfere with their function. Aim of the study is to investigate the influence of activated B cells on immunologic and regenerative properties of MSC. Materials and methods Highly purified CD19+B-cells were separated from PBMC by magnetic cell sorting. B-cells were polyclonally stimulated by B-cell-receptor cross-linking and IL-2 and cocultured with bone marrow derived MSC for various time periods. Cytokines were quantified after 72 hour by intracellular flow cytometry or in cell culture supernatants by ELISA and B cell division by flow cytometric methods at d5. Differentiation potential of MSC was assessed by use of established differentiation media in absence or presence of B cell culture supernatant. After 21 days differentiation into the osteogenic or adipogenic lineage was determined by fluorescence microscopy and quantified with ImageJ software. Results In MSC-B-cell cocultures the MSC-specific production of IL-6 and IL-8 increased by more than 100-fold compared to MSC single cultures. In contrast, B cell-specific production of TNF-alpha, Immunoglobulins and B cell proliferation diminished in B-MSC cocultures by more than 50% suggesting an inhibitory feedback mechanism by activated MSC towards the B cells. Separation of B cells from MSC by semipermeable cell culture inserts (transwell) did not abolish observed effects, suggesting that soluble factors were the main mediators. Of note, addition of neutralising antibodies against the B cell specific cytokines TNF-alpha and IL-1-beta significantly reduced MSC cytokine production in cocultures. B cells also influenced regenerative potential of MSC: in presence of B-cell supernatant MSC differentiation into the osteogenic lineage was significantly increased, accompanied by higher cell number, while differentiation into the adipogenic lineage was inhibited. Conclusions In presence of activated B cells MSC exert immunosuppressive effects.. However at the same time these MSC produce high amounts of proinflammatory cytokines and change their differentiation behaviour, suggesting an important influence of the cellular environment on MSC functions.

To identify risk factors for serum amyloid-A (AA) amyloidosis in patients living in Germany.Clinical and genetic data were obtained from 71 patients with AA amyloidosis. SAA1 genotypes were analyzed in 231 individuals. Control groups comprised 45 patients with long-standing inflammatory diseases without AA amyloidosis and 56 age-matched patients without any inflammatory disease.The most frequent underlying diseases of AA amyloidosis were familial Mediterranean fever (FMF) (n = 24, 34%) and inflammatory rheumatic diseases (n = 30, 42%). Patients without any known underlying disease (n = 11, 16%) were considered as having idiopathic AA amyloidosis. Patients with FMF were significantly younger at disease onset and younger at diagnosis of AA amyloidosis compared with patients with rheumatic diseases. Patients with idiopathic AA amyloidosis were older than patients with definite rheumatic diseases. Patients with FMF and high penetrance MEFV gene mutations had a relative risk of 1.73 for AA amyloidosis. Patients with FMF or a rheumatic disease and the SAA1 α/α genotype had a relative risk of 4.86 and 2.53, respectively, for developing an AA amyloidosis. The prevalence of this risk genotype was 36% in German patients without an inflammatory disease, 92% in German patients with AA amyloidosis and 100% in German patients with idiopathic AA amyloidosis.Risk factors for AA amyloidosis are the presence of a hereditary autoinflammatory or chronic rheumatic disease, elevated C-reactive protein and SAA serum levels, a long delay of a sufficient therapy, an advanced age and the SAA1α/α genotype.

Objective B cells with immunoregulatory properties (Breg cells) have been described in mice, but their role in the control of human immune responses is not well defined. We recently identified a human population of activated FSChigh B cells that exhibited regulatory activity toward T helper cells. The aim of the present study was to test such induced Breg (iBreg) cells in patients with autoimmune disease. Methods Purified CD19+FSChigh B cells derived from patients with systemic lupus erythematosus (SLE) or from healthy donors, which were activated via their B cell receptor, were cocultured with CD3-stimulated CD4+ T helper cells from SLE patients or healthy donors. 3H-thymidine incorporation, flow cytometry, and enzyme-linked immunosorbent assay (ELISA) were used to analyze proliferation, cytokine secretion, and surface marker expression. Results Although under costimulatory conditions, FSChigh SLE B cells supported the proliferation of healthy donor T cells to a similar extent as donor B cells, their regulatory function was significantly diminished in B cell suppressor assays. Similar effects were seen when SLE T cells were used, confirming that SLE T cells were equally susceptible to iBreg cell signals as healthy donor T cells and that SLE iBreg cell defects were independent of T cell origin. B cell viability and expression of surface markers (CD25, CD80, and B7-H1) or cytokines (interleukin-6 [IL-6], tumor necrosis factor α, and IL-10) were comparable in the two B cell populations. There was no correlation between the extent of iBreg cell–induced inhibition and disease activity. CD19+FSChigh B cells from patients with another systemic autoimmune disease, granulomatosis with polyangiitis (Wegener's) (GPA), exhibited no regulatory defects, which suggests that the iBreg cell defects were SLE-specific and not a general consequence of autoimmunity or inflammation. Conclusion Induced Breg cells from SLE patients, but not GPA patients, are less effective in the control of T helper cell proliferation, which supports the reported skewed B cell repertoire in SLE. The malfunctioning SLE iBreg cells might allow the overstimulation of immune responses and contribute to the initiation and/or perpetuation of disease.

Background: Systemic sclerosis (SSc)-overlap syndromes are a very heterogeneous and remarkable subgroup of SSc-patients, who present at least two connective tissue diseases (CTD) at the same time, usually with a specific autoantibody status. Objectives: To determine whether patients, classified as overlap syndromes, show a disease course different from patients with limited SSc (lcSSc) or diffuse cutaneous SSc (dcSSc). Methods: The data of 3240 prospectively included patients, registered in the database of the German Network for Systemic Scleroderma and followed between 2003 and 2013, were analysed. Results: Among 3240 registered patients, 10% were diagnosed as SSc-overlap syndrome. Of these, 82.5% were female. SSc-overlap patients had a mean age of 48±1.2 years and carried significantly more often ‘other antibodies’ (68.0%; p

Based on both historical development and functional advantages, such as in emergencies, hierarchical aspects dominate all levels of medicine. Doubtlessly, the high degree of respect for experts and their opinions may impede exchange between different levels of hierarchy. At medical conferences, discussions usually take place between experts, while patients, young doctors and students only listen and rarely actively participate. For the 11th European Lupus Meeting in Dusseldorf in March 2018, we have tried the fishbowl method to increase participation at all levels. Fishbowl is an interactive and dynamic technique with a group of discussants sitting in an inner circle that contains an additional empty chair and surrounded by the audience in an outer circle.1 The empty chair can be occupied by any member of the outer circle at any time to join the discussion immediately. After the additional discussant of the auditorium has made his/her statement, he or she will leave the chair again to create an opportunity for another member of the audience (figure 1). Figure 1 The fishbowl method. A group …

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation of the joints. Untreated RA leads to a destruction of joints through the erosion of cartilage and bone. The loss of physical function is the consequence. Early treatment is important to control disease activity and to prevent joint destruction. Nowadays, different classes of drugs with different modes of action are available to control the inflammation and to achieve remission. In this review, we want to discuss differences and similarities of these different drugs.

Objective.An increased incidence of apoptotic cells and an increased activation of dendritic cells (DC) may be involved in the pathogenesis of systemic lupus erythematosus (SLE). We investigated the characteristics of apoptotic neutrophils and monocyte-derived DC of patients with SLE, their interaction, and the influence of autoantibodies and inflammatory cytokines on this interaction.Methods.Kinetics of neutrophil apoptosis and DC activation were studied by flow cytometry. To analyze the interaction of apoptotic cells with phagocytes, crossover coculture experiments were performed with DC from patients with SLE and apoptotic Jurkat T cells as well as with apoptotic neutrophils from patients with SLE and the monocytic cell line U937. SLE serum and cytokines were added to this coculture, and activation and suppression of DC were quantified by levels of inflammatory cytokine secretion.Results.Apoptotic neutrophils and DC from patients with SLE showed no inherent defects compared to healthy controls, and the suppressive nature of their interaction was not affected. Autoantibodies as well as the inflammatory cytokines interleukin 17 (IL-17) and IL-1β had no influence on the interaction in this setup. Interferon (IFN)-α, however, substantially reduced the suppressive effect of apoptotic cells on DC.Conclusion.The data suggest that aberrant immune reactivity in SLE is not generally due to an intrinsic defect in apoptotic cells, their processing, or their interaction with DC, but likely arises from the milieu in which this interaction takes place. Our study highlights the importance of IFN-α during early stages of SLE and its potential as a therapeutic target.

The development of rheumatoid arthritis (RA) is linked to functional changes in synovial fibroblasts (SF) and local infiltration of T lymphocytes. Fibroblasts possess the capacity to suppress T cell responses, although the molecular mechanisms of this suppression remain incompletely understood. In this study, we aimed to define the mechanisms by which noninflammatory SF modulate Th cell responses and to determine the immunosuppressive efficacy of RASF. Hence, the influence of SF from osteoarthritis or RA patients on total Th cells or different Th cell subsets of healthy donors was analyzed in vitro. We show that SF strongly suppressed the proliferation of Th cells and the secretion of IFN-γ in a cell contact–independent manner. In cocultures of SF and Th cells, tryptophan was completely depleted within a few days, resulting in eukaryotic initiation factor 2α phosphorylation, TCRζ-chain downregulation, and proliferation arrest. Blocking IDO1 activity completely restored Th cell proliferation, but not IFN-γ production. Interestingly, only the proliferation of Th1 cells, but not of Th2 or Th17 cells, was affected. Finally, RASF had a significantly lower IDO1 expression and a weaker Th cell suppressive capacity compared with osteoarthritis SF. We postulate that the suppression of Th cell growth by SF through tryptophan catabolism may play an important role in preventing inappropriate Th cell responses under normal conditions. However, expansion of Th17 cells that do not induce IDO1-mediated suppression and the reduced capacity of RASF to restrict Th cell proliferation through tryptophan metabolism may support the initiation and propagation of synovitis in RA patients.

ObjectiveTo perform a detailed analysis of the autoantibody response against post-translationally modified proteins in patients with rheumatoid arthritis (RA) in sustained remission and to explore whether its composition influences the risk for disease relapse when tapering disease modifying antirheumatic drug (DMARD) therapy.MethodsImmune responses against 10 citrullinated, homocitrullinated/carbamylated and acetylated peptides, as well as unmodified vimentin (control) and cyclic citrullinated peptide 2 (CCP2) were tested in baseline serum samples from 94 patients of the RETRO study. Patients were classified according to the number of autoantibody reactivities (0–1/10, 2–5/10 and >5/10) or specificity groups (citrullination, carbamylation and acetylation; 0–3) and tested for their risk to develop relapses after DMARD tapering. Demographic and disease-specific parameters were included in multivariate logistic regression analysis for defining the role of autoantibodies in predicting relapse.ResultsPatients varied in their antimodified protein antibody response with the extremes from recognition of no (0/10) to all antigens (10/10). Antibodies against citrullinated vimentin (51%), acetylated ornithine (46%) and acetylated lysine (37%) were the most frequently observed subspecificities. Relapse risk significantly (p=0.011) increased from 18% (0–1/10 reactivities) to 34% (2–5/10) and 55% (>5/10). With respect to specificity groups (0–3), relapse risk significantly (p=0.021) increased from 18% (no reactivity) to 28%, 36% and finally to 52% with one, two or three antibody specificity groups, respectively.ConclusionsThe data suggest that the pattern of antimodified protein antibody response determines the risk of disease relapse in patients with RA tapering DMARD therapy.Trial registration number2009-015740-42; Results.

ObjectiveTo analyse the role of multibiomarker disease activity (MBDA) score in predicting disease relapses in patients with rheumatoid arthritis (RA) in sustained remission who tapered disease modifying antirheumatic drug (DMARD) therapy in RETRO, a prospective randomised controlled trial.MethodsMBDA scores (scale 1–100) were determined based on 12 inflammation markers in baseline serum samples from 94 patients of the RETRO study. MBDA scores were compared between patients relapsing or remaining in remission when tapering DMARDs. Demographic and disease-specific parameters were included in multivariate logistic regression analysis for defining predictors of relapse.ResultsModerate-to-high MBDA scores were found in 33% of patients with RA overall. Twice as many patients who relapsed (58%) had moderate/high MBDA compared with patients who remained in remission (21%). Baseline MBDA scores were significantly higher in patients with RA who were relapsing than those remaining in stable remission (N=94; p=0.0001) and those tapering/stopping (N=59; p=0.0001). Multivariate regression analysis identified MBDA scores as independent predictor for relapses in addition to anticitrullinated protein antibody (ACPA) status. Relapse rates were low (13%) in patients who were MBDA−/ACPA−, moderate in patients who were MBDA+/ACPA− (33.3%) and MBDA−ACPA+ (31.8%) and high in patients who were MBDA+/ACPA+ (76.4%).ConclusionsMBDA improved the prediction of relapses in patients with RA in stable remission undergoing DMARD tapering. If combined with ACPA testing, MBDA allowed prediction of relapse in more than 80% of the patients.Trial registration numberEudraCT 2009-015740-42.

Background The role of natural killer (NK) cells in granulomatosis with polyangiitis (GPA) is poorly understood. We recently reported that peripheral blood NK cell percentages correlate with the suppression of GPA activity (cohort I). The purpose of the current study was to further characterize NK cell subsets, phenotype and function in a second GPA cohort (cohort II). Methods Peripheral blood lymphocyte subsets were analyzed at a clinical diagnostic laboratory. Clinical data were extracted from medical records and patients were grouped according to their activity state (remission vs. active/non-remission). Separate analysis (cohort II, n = 22) and combined analysis (cohorts I and II, n = 34/57) of NK cell counts/percentages was performed. NK cell subsets and phenotypes were analyzed by multicolor flow cytometry. Cytotoxicity assays were performed using 51Cr-labeled K562 target cells. Results In cohort II, NK cell counts were lower than the lower limit of normal in active GPA, despite normal percentages due to lymphopenia. NK cell counts, but not other lymphocyte counts, were significantly higher in remission. Combined analysis of cohorts I and II confirmed decreased NK cell counts in active GPA and increased percentages in long-term remission. Follow-up measurements of six patients revealed increasing NK cell percentages during successful induction therapy. Multicolor analysis from cohort II revealed that in active GPA, the CD56dim subset was responsible for decreased NK cell counts, expressed more frequently CD69, downregulated the Fc-receptor CD16 and upregulated the adhesion molecule CD54, the chemokine receptor CCR5 and the activating receptor NKG2C. In remission, these markers were unaltered or marginally altered. All other receptors investigated (NKp30, NKp44, NKp46, NKG2D, DNAM1, 2B4, CRACC, 41BB) remained unchanged. Natural cytotoxicity was not detectable in most patients with active GPA, but was restored in remission. Conclusions NK cell numbers correlate inversely with GPA activity. Reduced CD56dim NK cells in active GPA have an activated phenotype, which intriguingly is associated with profound deficiency in cytotoxicity. These data suggest a function for NK cells in the pathogenesis and/or modulation of inflammation in GPA. NK cell numbers, phenotype (CD16, CD69, NKG2C) or overall natural cytotoxicity are promising candidates to serve as clinical biomarkers to determine GPA activity. Electronic supplementary material The online version of this article (doi:10.1186/s13075-016-1098-7) contains supplementary material, which is available to authorized users.