BACKGROUND:Mevalonate kinase deficiency (MKD) is a rare monogenic autoinflammatory disorder characterized by recurrent fever episodes driven by dysregulated IL-1β secretion. Mutations in the MVK gene cause enzymatic defects resulting in a shortage of geranylgeranyl pyrophosphate, leading to a lowering of the threshold for pyrin inflammasome activation. OBJECTIVE:A cellular model of MKD was established to discover novel inflammatory pathways contributing to disease pathogenesis, with a focus on IL-18 and IFN-γ signaling. METHODS:Using CRISPR/Cas9 gene editing, we generated a THP1 monocyte cell line harboring homozygous MVK I268T mutations, a pathogenic variant observed in patients with MKD. Functional assays were conducted to assess inflammasome activation and cytokine responses after stimulation with the pyrin agonist etiocholanolone. Experiments using MKD patient-derived peripheral blood mononuclear cells were performed to validate in vitro findings. RESULTS:MVKI268T/I268T THP1 cells exhibited impaired isoprenoid biosynthesis, consistent with the metabolic defect observed in MKD. Activation of the pyrin inflammasome in MVKI268T/I268T THP1 cells induced robust secretion of IL-1β and IL-18, which was attenuated by supplementation with geranylgeranyl pyrophosphate. MKD peripheral blood mononuclear cells hypersecreted IL-18 in response to pyrin inflammasome activation, reflected by elevated IL-18 levels in plasma of MKD patients. Specifically, MKD T and natural killer cells were characterized by enhanced IL-18-driven IFN-γ production. Elevated IFN-γ and IL-18 binding protein levels in MKD plasma as well as transcriptomic data of MKD peripheral blood mononuclear cells further confirmed the presence of an IFN-γ signature in MKD. CONCLUSION:A pyrin inflammasome-driven IL-18/IFN-γ axis is a key signaling module of MKD-associated inflammation. This pathway may represent a novel target for therapeutic intervention in MKD.

Ferroptosis and lipid peroxidation are associated with inflammatory and pathogenic conditions. However, cell-specific mechanisms and functions are not fully understood. Cysteine is an essential amino acid for T cell activation and proliferation and is required to synthesize glutathione, the most abundant antioxidant molecule in cells. Cysteine is predominantly produced intracellularly after uptake of its oxidized form (cystine) by SLC7A11. In this study, we provide a detailed analysis of lipid peroxidation in human T cells and analyzed functional consequences in the chronic inflammatory condition of childhood arthritis. We found that healthy peripheral blood CD4 T cells are not fully dependent on SLC7A11 expression and cystine uptake to prevent ferroptotic cell death, most likely by switching to ASCT1-mediated cysteine uptake. T cells from patients with JIA have a high ASCT1 expression, which most likely prevents exaggerated lipid peroxidation and enables them to maintain their inflammatory phenotype in challenging environments such as inflamed joints.

Juvenile idiopathic arthritis (JIA) is an autoimmune disease characterized by accumulation of activated CD4+ T cells in the synovial fluid (SF) of affected joints. JIA CD4+ T cells exhibit a unique inflammation-associated epigenomic signature, but the underlying mechanisms remain unclear. We demonstrate that CD4+ T cells from JIA SF display heightened glycolysis upon activation and JIA-specific H3K27 acetylation, driving transcriptional reprogramming. Pharmacological inhibition of glycolysis altered the expression of genes associated with these acetylated regions. Healthy CD4+ T cells exposed to JIA SF exhibited increased glycolytic activity and transcriptomic changes marked by heightened histone 3 lysine 27 acetylation (H3K27ac) at JIA-specific genes. Elevated H3K27ac was dependent on glycolytic flux, while inhibiting glycolysis or pyruvate dehydrogenase (PDH) impaired transcription of SF-driven genes. These findings demonstrate a key role of glycolysis in JIA-specific gene expression, offering potential therapeutic targets for modulating inflammation in JIA.

Juvenile Idiopathic Arthritis (JIA) describes a heterogeneous group of autoimmune conditions with an unknown cause and childhood onset. It is characterized by the accumulation of mononuclear cells, notably activated CD4+ memory/effector T (Tmem/Teff) cells, within the synovial fluid of affected joints. JIA CD4+ T cells exhibit a unique epigenomic signature linked to inflammation, however, the molecular mechanisms driving this remain unclear. Here we show that CD4+ T cells isolated from JIA synovial fluid (SF) exhibit abnormal intracellular metabolism marked by heightened glycolysis after activation driving transcriptional reprogramming. Epigenetic profiling between activated healthy controls and JIA patients allowed the definition of specific disease-related enhancers upregulated in SF-derived JIA CD4+ T cells. Pharmacological inhibition of glycolytic flux affected the expression of genes associated with these enhancers. When activated in the presence of JIA SF, CD4+ T cells obtained from healthy control (HC) subjects, displayed heightened glycolytic activity compared to paired plasma. Moreover, this also led to increased H3K27ac at JIA-specific genes. Increased H3K27ac was dependent on glycolytic flux, but not oxidative phosphorylation. Inhibition of glycolysis also specifically affected the transcription of genes upregulated during T cell activation in the presence of SF. Inhibiting the glycolytic enzyme pyruvate dehydrogenase (PDH) reduced JIA-associated gene expression. Taken together, these findings demonstrate that for JIA, the inflammatory microenvironment can modulate T cell activation-driven transcriptional programs through a glycolysis-mediated pathway. Specific targeting of this T cell metabolism-epigenetic axis may provide avenues for intervention during the development of autoinflammatory disease.

Objectives: To evaluate immunogenicity, effectiveness and safety of COVID-19 vaccination in patients with pediatric autoimmune inflammatory rheumatic disease (pedAIIRD). Methods: A prospective cohort study was performed at the pediatric rheumatology department of the Wilhelmina Children's Hospital in Utrecht, the Netherlands. Vaccination dates, COVID-19 cases and vaccine-related adverse events (AEs) were registered for all pedAIIRD patients during regular clinic visits from March 2021 - August 2022. SARS-CoV-2 IgG antibody levels and T-cell responses were measured from serum samples after vaccination, and clinical and drug therapy data were collected from electronic medical records. Rate of COVID-19 disease was compared between vaccinated and unvaccinated patients in a time-varying Cox regression analysis. Results: A total of 157 patients were included in this study and 88 % had juvenile idiopathic arthritis (JIA). One hundred thirty-seven patients were fully vaccinated, of which 47 % used biological agents at the time of vaccination, and 20 patients were unvaccinated. Geometric mean concentrations (GMCs) of post-vaccine antibody levels against SARS-CoV-2 were above the threshold for positivity in patients who did and did not use biological agents at the time of vaccination, although biological users demonstrated significantly lower antibody levels (adjusted GMC ratio: 0.38, 95 % CI: 0.21 - 0.70). T-cell responses were adequate in all but two patients (9 %). The adjusted rate of reported COVID-19 was significantly lower for fully vaccinated patients compared to non-vaccinated patients (HR: 0.53, 95 % CI: 0.29 - 0.97). JIA disease activity scores were not significantly different after vaccination, and no serious AEs were reported. Conclusions: COVID-19 mRNA vaccines were immunogenic (both cellular and humoral), effective and safe in a large cohort of pedAIIRD patients despite their use of immunosuppressive medication.

Background: CD4+ T cells critically contribute to the initiation and perturbation of inflammation. When CD4+ T cells enter inflamed tissues, they adapt to hypoxia and oxidative stress conditions, and to a reduction in nutrients. We aimed to investigate how this distinct environment regulates T cell responses within the inflamed joints of patients with childhood rheumatism (JIA) by analyzing the behavior of NRF2—the key regulator of the anti-oxidative stress response—and its signaling pathways. Methods: Flow cytometry and quantitative RT-PCR were used to perform metabolic profiling of T cells and to measure the production of inflammatory cytokines. Loss of function analyses were carried out by means of siRNA transfection experiments. NRF2 activation was induced by treatment with 4-octyl-Itaconate (4-OI). Results: Flow cytometry analyses revealed a high metabolic status in CD4+ T cells taken from synovial fluid (SF) with greater mitochondrial mass, and increased glucose and fatty acid uptake. This resulted in a heightened oxidative status of SF CD4+ T cells. Despite raised ROS levels, expression of NRF2 and its target gene NQO1 were lower in CD4+ T cells from SF than in those from blood. Indeed, NRF2 activation of CD4+ T cells downregulated oxidative stress markers, altered the metabolic phenotype and reduced secretion of IFN-γ. Conclusion: NRF2 could be a potential regulator in CD4+ T cells during chronic inflammation and could instigate a drift toward disease progression or regression, depending on the inflammatory environment.

OBJECTIVES:To evaluate the long-term efficacy and safety of canakinumab in patients with mevalonate kinase deficiency during the open label extension (weeks 41-113) of the randomized controlled CLUSTER trial. METHODS:During a 72-week period, patients received open-label canakinumab 150 or 300 mg, every 4 or 8 weeks. The disease activity was evaluated every 8 weeks using physician global assessment and counting the number of flares. Concentrations of CRP and serum amyloid A protein were measured. The safety was studied by determination and classification of observed adverse events. The safety and efficacy were analysed separately in three subgroups of patients receiving a cumulative dose of less than <35 mg/kg, ≥35 to <70 mg/kg or ≥70 mg/kg. RESULTS:Of the 74 patients who started the CLUSTER study, 66 entered Epoch 4 and 65 completed it. During the 72-week period, 42 (64%) patients experienced no flares, while 13 (20%) had one flare, as compared with a median of 12 flares per year reported at baseline. Low physician global assessment scores were seen at the end of the study for all groups with >90% reporting minimal disease activity or none at all. Median CRP concentrations were consistently equal or lower than 10 mg/l, while median serum amyloid A concentrations remained only slightly above the normal range of 10 mg/l. The study showed no new or unexpected adverse events. CONCLUSION:Canakinumab proved effective to control disease activity and prevent flares in mevalonate kinase deficiency during the 72-week study period. No new safety concerns were reported. TRIAL REGISTRATION:NCT02059291. https://clinicaltrials.gov.

Dendritic cells (DC) are crucial for initiating and shaping immune responses. So far, little is known about heterogeneity and functional specialization of human DC subsets in (local) inflammatory conditions. We profiled conventional (c)DC1, cDC2 and monocytes based on phenotype, transcriptome and function from a local inflammatory site, namely synovial fluid (SF) from patients suffering from a chronic inflammatory condition, Juvenile Idiopathic Arthritis (JIA). cDC1, a relatively small dendritic cell subset in blood, are strongly enriched in SF. SF cDC1 showed a quiescent immune signature without a clear inflammatory profile low expression of PRR, chemokine, and cytokine receptors, and poor induction of T cell proliferation and cytokine production, but selective production of IFNλ upon polyinosinic:polycytidylic acid exposure. In stark contrast, cDC2 and monocytes from the same environment, showed a pro-inflammatory transcriptional profile, high levels of (spontaneous) pro-inflammatory cytokine production, and strong induction of T cell proliferation and cytokine production, including IL-17. Although the cDC2 and monocytes showed an overlapping transcriptional core profile, there were clear differences in the transcriptional landscape and functional features, indicating that these cell types retain their lineage identity in chronic inflammatory conditions. In conclusion, our findings suggest that at the site of inflammation, there is specific functional programming of human DC subsets, especially cDC2. In contrast, the enriched subset of cDC1 remains relatively quiescent and seemingly unchanged under inflammatory conditions, pointing to a more regulatory role.

T lymphocytes accumulate in inflamed tissues of patients with chronic inflammatory diseases (CIDs) and express pro-inflammatory cytokines upon re-stimulation in vitro. Further, a significant genetic linkage to MHC genes suggests that T lymphocytes play an important role in the pathogenesis of CIDs including juvenile idiopathic arthritis (JIA). However, the functions of T lymphocytes in established disease remain elusive. Here we dissect the transcriptional and the clonal heterogeneity of synovial T lymphocytes in JIA patients by single-cell RNA sequencing combined with T cell receptor profiling on the same cells. We identify clonally expanded subpopulations of T lymphocytes expressing genes reflecting recent activation by antigen in situ. A PD-1+ TOX+ EOMES+ population of CD4+ T lymphocytes expressed immune regulatory genes and chemoattractant genes for myeloid cells. A PD-1+ TOX+ BHLHE40+ population of CD4+ , and a mirror population of CD8+ T lymphocytes expressed genes driving inflammation, and genes supporting B lymphocyte activation in situ. This analysis points out that multiple types of T lymphocytes have to be targeted for therapeutic regeneration of tolerance in arthritis.

Invariant Natural Killer T (iNKT) cells respond to the ligation of lipid antigen-CD1d complexes via their T-cell receptor and are implicated in various immunometabolic diseases. We considered that immunometabolic factors might affect iNKT cell function. To this end, we investigated iNKT cell phenotype and function in a cohort of adolescents with chronic disease and immunometabolic abnormalities. We analyzed peripheral blood iNKT cells of adolescents with cystic fibrosis (CF, n = 24), corrected coarctation of the aorta (CoA, n = 25), juvenile idiopathic arthritis (JIA, n = 20), obesity (OB, n = 20), and corrected atrial septal defect (ASD, n = 25) as controls. To study transcriptional differences, we performed RNA sequencing on a subset of obese patients and controls. Finally, we performed standardized co-culture experiments using patient plasma, to investigate the effect of plasma factors on iNKT cell function. We found comparable iNKT cell numbers across patient groups, except for reduced iNKT cell numbers in JIA patients. Upon ex-vivo activation, we observed enhanced IFN-γ/IL-4 cytokine ratios in iNKT cells of obese adolescents versus controls. The Th1-skewed iNKT cell cytokine profile of obese adolescents was not explained by a distinct transcriptional profile of the iNKT cells. Co-culture experiments with patient plasma revealed that across all patient groups, obesity-associated plasma factors including LDL-cholesterol, leptin, and fatty-acid binding protein 4 (FABP4) coincided with higher IFN-γ production, whereas high HDL-cholesterol and insulin sensitivity (QUICKI) coincided with higher IL-4 production. LDL and HDL supplementation in co-culture studies confirmed the effects of lipoproteins on iNKT cell cytokine production. These results suggest that circulating immunometabolic factors such as lipoproteins may be involved in Th1 skewing of the iNKT cell cytokine response in immunometabolic disease.

Purpose Patients with juvenile idiopathic arthritis (JIA) are prone to developing chronic anterior uveitis (JIA-U+). Although several risk factors for JIA-U+ have been identified, the underlying etiology is poorly understood. Histopathological studies demonstrate B cell infiltrates in eye tissues of patients with JIA-U+. Methods We performed transcriptome profiling of peripheral blood CD19-positive B cells taken from 14 cases with JIA-U+, 13 JIA cases without uveitis (JIA-U-), and five healthy controls. Deconvolution-based estimation was used to determine the immune cell fractions for each sample. Results Deconvolution results revealed that naive B cells made up on average 71% of the CD19-positive cell fractions analyzed. Differential expression analysis identified 614 differentially expressed genes (DEGs) between the groups at nominal significance and six genes at a false discovery rate of 5% (FDR < 0.05). Head-to-head comparison of all JIA-U- versus JIA-U+ revealed no DEGs in the CD19+ B cell pool (FDR < 0.05). However, principal component analysis based on a panel of key genes for B cell subsets revealed that JIA-U+ cases bifurcate into distinct clusters, characterized by markedly disparate expression for genes associated with specific memory B cell populations. CIBERSORT analysis of the overall transcriptome of the new uveitis cluster identified an increased proportion of memory B cells. Conclusion These data show that JIA-U- and JIA-U+ have a globally similar transcriptome considering the global peripheral CD19-positive B cell pool. However, heterogeneity in B cell memory genes among cases with uveitis suggests a role for specific memory B cell subsets in the etiology of JIA-U+.

Objectives. The European initiative Single Hub and Access point for paediatric Rheumatology in Europe (SHARE) aimed to optimize care for children with rheumatic diseases. Systemic vasculitides are very rare in children. Consequently, despite recent advances, paediatric-specific information is sparse. The lack of evidence-based recommendations is an important, unmet need. This study aimed to provide recommendations for diagnosing and treating children with rare forms of childhood systemic vasculitis. Methods. Recommendations were developed by a consensus process in accordance with the European League Against Rheumatism standard operating procedures. A systematic literature review informed the recommendations, which were devised and evaluated by a panel of experts via an online survey, and two consensus meetings using nominal group technique. Recommendations were accepted when 5 80% of experts agreed. Results. Ninety-three relevant articles were found, and 78 recommendations were accepted in the two consensus meetings. General, cross-cutting recommendations and disease-specific statements regarding the diagnosis and treatment of childhood-onset PAN, granulomatosis with polyangiitis, microscopic polyangiitis, eosinophilic granulomatosis with polyangiitis, and Takayasu arteritis are provided. Conclusion. These Single Hub and Access point for paediatric Rheumatology in Europe recommendations were formulated through an evidence-based consensus process to support uniform, high-quality standard of care for children with rare forms of paediatric systemic vasculitis.

Objectives The European Single Hub and Access point for paediatric Rheumatology in Europe initiative aimed to optimize care for children with rheumatic diseases. Kawasaki disease (KD) is the most common cause of acquired heart disease in children and an important cause of long-term cardiac disease into adulthood. Prompt diagnosis and treatment of KD is difficult due to the heterogeneity of the disease but is crucial for improving outcome. To date, there are no European internationally agreed, evidence-based guidelines concerning the diagnosis and treatment of KD in children. Accordingly, treatment regimens differ widely. The aim of this study is to provide consensus-based, European-wide evidence-informed recommendations for diagnosis and treatment of children with KD. Methods Recommendations were developed using the EULAR’s standard operating procedures. An extensive systematic literature search was performed, and evidence-based recommendations were extrapolated from the included papers. These were evaluated by a panel of international experts via online surveys and subsequently discussed in three consensus meetings, using nominal group technique. Recommendations were accepted when ⩾80% agreed. Results In total, 17 recommendations for diagnosis and 14 for treatment of KD in children were accepted. Diagnostic recommendations included laboratory and imaging workup for complete as well as incomplete KD. Treatment recommendations included the importance of early treatment in both complete and incomplete KD, use of intravenous immunoglobulin, aspirin, corticosteroids for high-risk cases, and other treatment options for those with resistant disease. Conclusion The Single Hub and Access point for paediatric Rheumatology in Europe initiative provides international evidence-based recommendations for diagnosing and treating KD in children, facilitating improvement and uniformity of care.

Objectives The European initiative Single Hub and Access point for paediatric Rheumatology in Europe (SHARE) aimed to optimize care for children with rheumatic diseases. Systemic vasculitides are very rare in children. Consequently, despite recent advances, paediatric-specific information is sparse. The lack of evidence-based recommendations is an important, unmet need. This study aimed to provide recommendations for diagnosing and treating children with rare forms of childhood systemic vasculitis. Methods Recommendations were developed by a consensus process in accordance with the European League Against Rheumatism standard operating procedures. A systematic literature review informed the recommendations, which were devised and evaluated by a panel of experts via an online survey, and two consensus meetings using nominal group technique. Recommendations were accepted when ⩾ 80% of experts agreed. Results Ninety-three relevant articles were found, and 78 recommendations were accepted in the two consensus meetings. General, cross-cutting recommendations and disease-specific statements regarding the diagnosis and treatment of childhood-onset PAN, granulomatosis with polyangiitis, microscopic polyangiitis, eosinophilic granulomatosis with polyangiitis, and Takayasu arteritis are provided. Conclusion These Single Hub and Access point for paediatric Rheumatology in Europe recommendations were formulated through an evidence-based consensus process to support uniform, high-quality standard of care for children with rare forms of paediatric systemic vasculitis.

Recent work has started to provide evidence that cellular metabolism is critical in the regulation of immune cell differentiation and function, thereby influencing the final outcome of both the adaptive and innate immune response. Upon engagement of the T Cell Receptor (TCR) after antigen recognition, T cells rapidly upregulate aerobic glycolysis, a process often termed the Warburg effect. It has become clear that this switch to aerobic glycolysis is essential for T cell proliferation, differentiation, and function. However, glycolysis is extremely inefficient for ATP production, suggesting that likely has alternative roles during T cells activation.Using a combination of RNAseq, ChIP‐seq, and metabolomics, our results show for the first time that after TCR engagement, pyruvate produced by induction of glycolysis is essential to remodel the human CD4+ T cell epigenome. Pyruvate is translocated to the nucleus where it is converted to acetyl‐CoA and can act as a co‐factor for histone acetyltransferases (HATs) resulting in chromatin remodeling and subsequent expression of T cell activation markers. Preventing TCR‐induced pyruvate generation severely impacts T cell activation and transcriptional reprogramming. We further show that inflammatory microenvironment can reprogram CD4+ T cell metabolism and through epigenetic reprogramming can thereby trigger aberrant, pathogenic gene expression.Taken together our findings demonstrate a direct link between cellular metabolism, chromatin remodeling, and T cell function/fate. Understanding the influence of metabolic alterations in inflammatory environments and there impact on chromatin remodeling may result in the design of novel interventions to specifically target these pathways and alter T cell function.Support or Funding InformationThis work was supported by a grant from the Dutch Arthritis Society (ReumaNederland)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Introduction/Abstract T lymphocytes accumulate in inflamed tissues of patients with chronic inflammatory diseases (CIDs) and express pro-inflammatory cytokines upon re-stimulation in vitro 1–29 . Further, a significant genetic linkage to MHC genes suggests that T lymphocytes play an important role in the pathogenesis of CIDs including juvenile idiopathic arthritis (JIA) 30–33 . However, the functions of T lymphocytes in established disease remain elusive. Here we dissect the heterogeneity of synovial T lymphocytes in JIA patients by single cell RNA-sequencing. We identify subpopulations of T lymphocytes expressing genes reflecting recent activation by antigen in situ . A PD-1 + TOX + EOMES + population of CD4 + T lymphocytes expressed immune regulatory genes and chemoattractant genes for myeloid cells. A PD-1 + TOX + BHLHE40 + population of CD4 + , and a mirror population of CD8 + T lymphocytes expressed genes driving inflammation, and genes supporting B lymphocyte activation. This analysis points out that multiple types of T lymphocytes have to be targeted for therapeutic regeneration of tolerance in arthritis.

Background The term systemic juvenile idiopathic arthritis (sJIA) describes an autoinflammatory condition characterized by arthritis and severe systemic inflammation, which in later stages can transform into interleukin (IL)-17-driven autoimmune arthritis. IL-1 antagonists have been used with good efficacy in the early stages of sJIA. Methods A whole transcriptome analysis of peripheral blood RNA samples was performed in six patients with sJIA and active systemic disease, before initiating treatment with the IL-1β receptor antagonist anakinra, and after induction of inactive disease, compared with a single-sample control cohort of 21 patients in several clinical stages of sJIA activity. Whole transcriptomes were compared longitudinally and interindividually including gene ontology and motif enrichment analysis of differentially expressed genes. Results There were 741 transcripts were identified using a threshold with a p value <0.01 and a fold change > 2. HLADRB1 and CD74 were identified as the most strongly upregulated genes in inactive compared to active disease; CD177 expression was significantly enhanced in active disease compared to inactive disease. Motif enrichment analysis revealed STAT4, BCL6, and STAT3 as the most prominent transcription factors that were present during active disease. In addition, strong upregulation of the major histocompatability complex II (MHCII) ligand CD74 was found in both active and inactive sJIA compared to healthy controls. Conclusion Using transcription factor motif enrichment, this study identifies novel putative pathways in sJIA (STAT4, BCL6) implicating B cell activation at an earlier stage than predicted in refractory disease. The implication of BCL-6 dependent pathways argues for occurrence of autoimmunity early within the process of sJIA chronification. Transcriptional regulation of HLA-DRB1, a recently described independent genetic risk factor, in combination with its cooperating partner CD74 in patients where sJIA is confirmed, supports pathogenic involvement in alterations in antigen presentation during sJIA.

In the past decades, we have gained important insights into the mechanisms of disease and therapy underlying chronic inflammation in juvenile idiopathic arthritis (JIA). These insights have resulted in several game-changing therapeutic modalities for many patients. However, additional progress still has to be made with regard to efficacy, cost reduction, minimization of side effects, and dose-tapering and stop strategies of maintenance drugs. Moreover, to really transform the current therapeutic strategies into personalized medicine, we need validated biomarkers to translate increased insights into clinical practice. In this article, we describe recent developments in JIA research and outline how clinical innovations need to go hand in hand with basic discoveries to really effect care for patients. Facilitating the transition from bench to bedside is crucial for addressing the major current challenges in JIA management. When successful, it will set new standards for a safe, targeted, and personalized medicine in JIA.

Childhood-onset systemic lupus erythematosus (cSLE) is a rare, multisystem and potentially life-threatening autoimmune disorder with significant associated morbidity. Evidence-based guidelines are sparse and management is often based on clinical expertise. SHARE (Single Hub and Access point for paediatric Rheumatology in Europe) was launched to optimise and disseminate management regimens for children and young adults with rheumatic diseases like cSLE. Here, we provide evidence-based recommendations for diagnosis and treatment of cSLE. In view of extent and complexity of cSLE and its various manifestations, recommendations for lupus nephritis and antiphospholipid syndrome will be published separately. Recommendations were generated using the EULAR (European League Against Rheumatism) standard operating procedure. An expert committee consisting of paediatric rheumatologists and representation of paediatric nephrology from across Europe discussed evidence-based recommendations during two consensus meetings. Recommendations were accepted if >80% agreement was reached. A total of 25 recommendations regarding key approaches to diagnosis and treatment of cSLE were made. The recommendations include 11 on diagnosis, 9 on disease monitoring and 5 on general treatment. Topics included: appropriate use of SLE classification criteria, disease activity and damage indices; adequate assessment of autoantibody profiles; secondary macrophage activation syndrome; use of hydroxychloroquine and corticosteroid-sparing regimens; and the importance of addressing poor adherence. Ten recommendations were accepted regarding general diagnostic strategies and treatment indications of neuropsychiatric cSLE. The SHARE recommendations for cSLE and neuropsychiatric manifestations of cSLE have been formulated by an evidence-based consensus process to support uniform, high-quality standards of care for children with cSLE.