Emergent high fatality lung disease in systemic juvenile arthritis

OBJECTIVE

To investigate the characteristics and risk factors of a novel parenchymal lung disease (LD), increasingly detected in systemic juvenile idiopathic arthritis (sJIA).

METHODS

In a multicentre retrospective study, 61 cases were investigated using physician-reported clinical information and centralised analyses of radiological, pathological and genetic data.

RESULTS

LD was associated with distinctive features, including acute erythematous clubbing and a high frequency of anaphylactic reactions to the interleukin (IL)-6 inhibitor, tocilizumab. Serum ferritin elevation and/or significant lymphopaenia preceded LD detection. The most prevalent chest CT pattern was septal thickening, involving the periphery of multiple lobes ± ground-glass opacities. The predominant pathology (23 of 36) was pulmonary alveolar proteinosis and/or endogenous lipoid pneumonia (PAP/ELP), with atypical features including regional involvement and concomitant vascular changes. Apparent severe delayed drug hypersensitivity occurred in some cases. The 5-year survival was 42%. Whole exome sequencing (20 of 61) did not identify a novel monogenic defect or likely causal PAP-related or macrophage activation syndrome (MAS)-related mutations. Trisomy 21 and young sJIA onset increased LD risk. Exposure to IL-1 and IL-6 inhibitors (46 of 61) was associated with multiple LD features. By several indicators, severity of sJIA was comparable in drug-exposed subjects and published sJIA cohorts. MAS at sJIA onset was increased in the drug-exposed, but was not associated with LD features.

CONCLUSIONS

A rare, life-threatening lung disease in sJIA is defined by a constellation of unusual clinical characteristics. The pathology, a PAP/ELP variant, suggests macrophage dysfunction. Inhibitor exposure may promote LD, independent of sJIA severity, in a small subset of treated patients. Treatment/prevention strategies are needed.

Systemic Juvenile Idiopathic Arthritis-Associated Lung Disease: Characterization and Risk Factors

OBJECTIVE

Systemic juvenile idiopathic arthritis (JIA) is associated with a recently recognized, albeit poorly defined and characterized, lung disease (LD). The objective of this study was to describe the clinical characteristics, risk factors, and histopathologic and immunologic features of this novel inflammatory LD associated with systemic JIA (designated SJIA-LD).

METHODS

Clinical data collected since 2010 were abstracted from the medical records of patients with systemic JIA from the Cincinnati Children's Hospital Medical Center. Epidemiologic, cellular, biochemical, genomic, and transcriptional profiling analyses were performed.

RESULTS

Eighteen patients with SJIA-LD were identified. Radiographic findings included diffuse ground-glass opacities, subpleural reticulation, interlobular septal thickening, and lymphadenopathy. Pathologic findings included patchy, but extensive, lymphoplasmacytic infiltrates and mixed features of pulmonary alveolar proteinosis (PAP) and endogenous lipoid pneumonia. Compared to systemic JIA patients without LD, those with SJIA-LD were younger at the diagnosis of systemic JIA (odds ratio [OR] 6.5, P = 0.007), more often had prior episodes of macrophage activation syndrome (MAS) (OR 14.5, P < 0.001), had a greater frequency of adverse reactions to biologic therapy (OR 13.6, P < 0.001), and had higher serum levels of interleukin-18 (IL-18) (median 27,612 pg/ml versus 5,413 pg/ml; P = 0.047). Patients with SJIA-LD lacked genetic, serologic, or functional evidence of granulocyte-macrophage colony-stimulating factor pathway dysfunction, a feature that is typical of familial or autoimmune PAP. Moreover, bronchoalveolar lavage (BAL) fluid from patients with SJIA-LD rarely demonstrated proteinaceous material and had less lipid-laden macrophages than that seen in patients with primary PAP (mean 10.5% in patients with SJIA-LD versus 66.1% in patients with primary PAP; P < 0.001). BAL fluid from patients with SJIA-LD contained elevated levels of IL-18 and the interferon-γ-induced chemokines CXCL9 and CXCL10. Transcriptional profiling of the lung tissue from patients with SJIA-LD identified up-regulated type II interferon and T cell activation networks. This signature was also present in SJIA-LD human lung tissue sections that lacked substantial histopathologic findings, suggesting that this activation signature may precede and drive the lung pathology in SJIA-LD.

CONCLUSION

Pulmonary disease is increasingly detected in children with systemic JIA, particularly in association with MAS. This entity has distinct clinical and immunologic features and represents an uncharacterized inflammatory LD.

A Multiparameter Flow Cytometry Analysis Panel to Assess CD163 mRNA and Protein in Monocyte and Macrophage Populations in Hyperinflammatory Diseases

CD163 facilitates regulation and resolution of inflammation and removal of free hemoglobin and is highly expressed in myeloid cells from patients with inflammatory disorders, such as systemic juvenile idiopathic arthritis (SJIA) and macrophage activation syndrome (MAS). Our recent studies indicate that regulation of CD163 mRNA expression is a key functional property of polarized monocytes and macrophages and is mediated at the transcriptional and posttranscriptional level, including via microRNAs. The goal of the current study is to develop a multiparameter flow cytometry panel incorporating detection of CD163 mRNA for polarized monocyte and macrophage populations in disorders such as SJIA and MAS. THP-1 cells and CD14⁺ human monocytes were stained using fluorochrome-conjugated Abs to myeloid surface markers, along with CD163 mRNA. Staining for mRNA could reliably detect CD163 expression while simultaneously detecting different macrophage populations using Abs targeting CD14, CD64, CD80, CD163, and CD209. This approach was found to be highly sensitive for increased mRNA expression when macrophages were polarized with IL-10 [M(IL-10)], with a strong signal over a broad range of IL-10 concentrations, and showed distinct kinetics of CD163 mRNA and protein induction upon IL-10 stimulation. Finally, this panel demonstrated clear changes in polarization markers in unstimulated monocytes from patients with SJIA and MAS, including upregulated CD163 mRNA and increased CD64 expression. This approach represents a robust and sensitive system for RNA flow cytometry, useful for studying CD163 expression as part of a multimarker panel for human monocytes and macrophages, with broad applicability to the pathogenesis of hyperinflammatory diseases.

Serum S100A8/A9 and S100A12 Levels in Children With Polyarticular Forms of Juvenile Idiopathic Arthritis: Relationship to Maintenance of Clinically Inactive Disease During Anti-Tumor Necrosis Factor Therapy and Occurrence of Disease Flare After Discontinuation of Therapy

OBJECTIVE

To determine the relationship between serum levels of S100A8/A9 and S100A12 and the maintenance of clinically inactive disease during anti-tumor necrosis factor (anti-TNF) therapy and the occurrence of disease flare following withdrawal of anti-TNF therapy in patients with polyarticular forms of juvenile idiopathic arthritis (JIA).

METHODS

In this prospective, multicenter study, 137 patients with polyarticular-course JIA whose disease was clinically inactive while receiving anti-TNF therapy were enrolled. Patients were observed for an initial 6-month phase during which anti-TNF treatment was continued. For those patients who maintained clinically inactive disease over the 6 months, anti-TNF was withdrawn and they were followed up for 8 months to assess for the occurrence of flare. Serum S100 levels were measured at baseline and at the time of anti-TNF withdrawal. Spearman's rank correlation test, Mann-Whitney U test, Kruskal-Wallis test, receiver operating characteristic (ROC) curve, and Kaplan-Meier survival analyses were used to assess the relationship between serum S100 levels and maintenance of clinically inactive disease and occurrence of disease flare after anti-TNF withdrawal.

RESULTS

Over the 6-month initial phase with anti-TNF therapy, the disease state reverted from clinically inactive to clinically active in 24 (18%) of the 130 evaluable patients with polyarticular-course JIA; following anti-TNF withdrawal, 39 (37%) of the 106 evaluable patients experienced a flare. Serum levels of S100A8/A9 and S100A12 were elevated in up to 45% of patients. Results of the ROC analysis revealed that serum S100 levels did not predict maintenance of clinically inactive disease during anti-TNF therapy nor did they predict disease flare after treatment withdrawal. Elevated levels of S100A8/A9 were not predictive of the occurrence of a disease flare within 30 days, 60 days, 90 days, or 8 months following anti-TNF withdrawal, and elevated S100A12 levels had a modest predictive ability for determining the risk of flare within 30, 60, and 90 days after treatment withdrawal. Serum S100A12 levels at the time of anti-TNF withdrawal were inversely correlated with the time to disease flare (r = -0.36).

CONCLUSION

Serum S100 levels did not predict maintenance of clinically inactive disease or occurrence of disease flare in patients with polyarticular-course JIA, and S100A12 levels were only moderately, and inversely, correlated with the time to disease flare.

Neutrophils From Children With Systemic Juvenile Idiopathic Arthritis Exhibit Persistent Proinflammatory Activation Despite Long-Standing Clinically Inactive Disease

Background: Systemic juvenile idiopathic arthritis (SJIA) is a chronic childhood arthropathy with features of autoinflammation. Early inflammatory SJIA is associated with expansion and activation of neutrophils with a sepsis-like phenotype, but neutrophil phenotypes present in longstanding and clinically inactive disease (CID) are unknown. The objective of this study was to examine activated neutrophil subsets, S100 alarmin release, and gene expression signatures in children with a spectrum of SJIA disease activity.

Methods: Highly-purified neutrophils were isolated using a two-step procedure of density-gradient centrifugation followed by magnetic-bead based negative selection prior to flow cytometry or cell culture to quantify S100 protein release. Whole transcriptome gene expression profiles were compared in neutrophils from children with both active SJIA and CID.

Results: Patients with SJIA and active systemic features demonstrated a higher proportion of CD16⁺CD62L^lo neutrophil population compared to controls. This neutrophil subset was not seen in patients with CID or patients with active arthritis not exhibiting systemic features. Using imaging flow cytometry, CD16⁺CD62L^lo neutrophils from patients with active SJIA and features of macrophage activation syndrome (MAS) had increased nuclear hypersegmentation compared to CD16⁺CD62L⁺ neutrophils. Serum levels of S100A8/A9 and S100A12 were strongly correlated with peripheral blood neutrophil counts. Neutrophils from active SJIA patients did not show enhanced resting S100 protein release; however, regardless of disease activity, neutrophils from SJIA patients did show enhanced S100A8/A9 release upon PMA stimulation compared to control neutrophils. Furthermore, whole transcriptome analysis of highly purified neutrophils from children with active SJIA identified 214 differentially expressed genes (DEG) compared to neutrophils from healthy controls. The most significantly upregulated gene pathway was Immune System Process, including AIM2, IL18RAP, and NLRC4. Interestingly, this gene set showed intermediate levels of expression in neutrophils from patients with long-standing CID yet persistent serum IL-18 elevation. Indeed, all patient samples regardless of disease activity demonstrated elevated inflammatory gene expression, including inflammasome components and S100A8.

Conclusion: We identify features of neutrophil activation in SJIA patients with both active disease and CID, including a proinflammatory gene expression signature, reflecting persistent innate immune activation. Taken together, these studies expand understanding of neutrophil function in chronic autoinflammatory disorders such as SJIA.

Identification of enhanced IFN-γ signaling in polyarticular juvenile idiopathic arthritis with mass cytometry

Polyarticular juvenile idiopathic arthritis (JIA) is among the most challenging of the JIA subtypes to treat. Even with current biologic therapies, the disease remains difficult to control in a substantial subset of patients, highlighting the need for new therapies. The aim of this study was to use the high dimensionality afforded by mass cytometry with phospho-specific antibodies to delineate signaling abnormalities in immune cells from treatment-naive polyarticular JIA patients. Peripheral blood mononuclear cells were isolated from 17 treatment-naive polyarticular JIA patients, 10 of the patients after achieving clinical remission, and 19 healthy controls. Samples were stimulated for 15 minutes with IL-6 or IFN-γ and analyzed by mass cytometry. Following IFN-γ stimulation, increased STAT1 and/or STAT3 phosphorylation was observed in subsets of CD4 T cells and classical monocytes from treatment-naive patients. The enhanced IFN-γ signaling was associated with increased expression of JAK1 and SOCS1 in CD4 T cells. Furthermore, substantial heterogeneity in surface marker expression was observed among the subsets of CD4 T cells and classical monocytes with increased IFN-γ responsiveness. The identification of enhanced IFN-γ signaling in CD4 T cells and classical monocytes from treatment-naive polyarticular JIA patients provides mechanistic support for investigations into therapies that attenuate IFN-γ signaling in this disease.

IL1RN Variation Influences Both Disease Susceptibility and Response to Recombinant Human Interleukin-1 Receptor Antagonist Therapy in Systemic Juvenile Idiopathic Arthritis

OBJECTIVE

To determine whether systemic juvenile idiopathic arthritis (JIA) susceptibility loci that were identified by candidate gene studies demonstrate association with systemic JIA in the largest study population assembled to date.

METHODS

Single-nucleotide polymorphisms (SNPs) from 11 previously reported systemic JIA risk loci were examined for association in 9 populations, including 770 patients with systemic JIA and 6,947 controls. The effect of systemic JIA-associated SNPs on gene expression was evaluated in silico in paired whole genome and RNA sequencing data from the lymphoblastoid cell lines (LCLs) of 373 European subjects from the 1000 Genomes Project. Responses of systemic JIA-associated SNPs to anakinra treatment were evaluated in 38 US patients for whom treatment response data were available.

RESULTS

We found no association between the previously reported 26 SNPs and systemic JIA. Expanded analysis of the regions containing the 26 SNPs revealed only 1 significant association: the promoter region of IL1RN (P < 1 × 10-4 ). Systemic JIA-associated SNPs correlated with IL1RN expression in LCLs, with an inverse correlation between systemic JIA risk and IL1RN expression. The presence of homozygous IL1RN high expression alleles correlated strongly with a lack of response to anakinra therapy (odds ratio 28.7 [95% confidence interval 3.2-255.8]).

CONCLUSION

In our study, IL1RN was the only candidate locus associated with systemic JIA. The implicated SNPs are among the strongest known determinants of IL1RN and interleukin-1 receptor antagonist levels, linking low expression with increased systemic JIA risk. Homozygous high expression alleles predicted nonresponsiveness to anakinra therapy, making them ideal candidate biomarkers to guide systemic JIA treatment. This study is an important first step toward the personalized treatment of systemic JIA.

Risk, Timing, and Predictors of Disease Flare After Discontinuation of Anti-Tumor Necrosis Factor Therapy in Children With Polyarticular Forms of Juvenile Idiopathic Arthritis With Clinically Inactive Disease

OBJECTIVE

To determine the frequency, time to flare, and predictors of disease flare upon withdrawal of anti-tumor necrosis factor (anti-TNF) therapy in children with polyarticular forms of juvenile idiopathic arthritis (JIA) who demonstrated ≥6 months of continuous clinically inactive disease.

METHODS

In 16 centers 137 patients with clinically inactive JIA who were receiving anti-TNF therapy (42% of whom were also receiving methotrexate [MTX]) were prospectively followed up. If the disease remained clinically inactive for the initial 6 months of the study, anti-TNF was stopped and patients were assessed for flare at 1, 2, 3, 4, 6, and 8 months. Life-table analysis, t-tests, chi-square test, and Cox regression analysis were used to identify independent variables that could significantly predict flare by 8 months or time to flare.

RESULTS

Of 137 patients, 106 (77%) maintained clinically inactive disease while receiving anti-TNF therapy for the initial 6 months and were included in the phase of the study in which anti-TNF therapy was stopped. Stopping anti-TNF resulted in disease flare in 39 (37%) of 106 patients by 8 months. The mean/median ± SEM time to flare was 212/250 ± 9.77 days. Patients with shorter disease duration at enrollment, older age at onset and diagnosis, shorter disease duration prior to experiencing clinically inactive disease, and shorter time from onset of clinically inactive disease to enrollment were found to have significantly lower hazard ratios for likelihood of flare by 8 months (P < 0.05).

CONCLUSION

Over one-third of patients with polyarticular JIA with sustained clinically inactive disease will experience a flare by 8 months after discontinuation of anti-TNF therapy. Several predictors of lower likelihood of flare were identified.

Brief Report: Novel UNC13D Intronic Variant Disrupting an NF-κB Enhancer in a Patient With Recurrent Macrophage Activation Syndrome and Systemic Juvenile Idiopathic Arthritis

OBJECTIVE

Macrophage activation syndrome (MAS) is a life-threatening complication of systemic juvenile idiopathic arthritis (JIA) and has pathologic similarity to hemophagocytic lymphohistiocytosis (HLH). Intronic variants in UNC13D are found in patients with familial HLH type 3 (FHLH3), but the role of noncoding variants in MAS is unknown. The objective of this study was to identify deep intronic UNC13D variants in patients with MAS.

METHODS

A custom enrichment library was constructed to sequence a genomic region of ~1 Mb flanking UNC13D in 24 patients with systemic JIA, recurrent MAS, and negative results of prior genetic (exon/coding) testing. The functional consequences of intronic variants were assessed using quantitative polymerase chain reaction in patient-derived peripheral blood mononuclear cells (PBMCs), electromobility shift assay, in vitro transcriptional enhancer assays, and natural killer (NK) cell degranulation assays.

RESULTS

We evaluated a patient with systemic JIA and recurrent MAS in whom a novel functional intronic variant in UNC13D, c.117+143A>G, was observed. This variant occurred in a proposed regulatory region that drives lymphocyte-specific UNC13D expression and is associated with reduced transcript levels in patient PBMCs. This variant also disrupted NF-κB binding to a functional transcriptional enhancer, leading to reduced enhancer activity in vitro. Partial knockdown of UNC13D expression also led to impaired NK cell degranulation. An additional patient was identified with a previously described UNC13D intronic variant, for a total noncoding variant hit rate of 8.3% (2 of 24).

CONCLUSION

These findings highlight the notion that intronic variants in key regulatory regions may be associated with MAS in patients with systemic JIA and support deep sequencing approaches when causative coding variants are not identified.

Novel UNC13D intronic variant disrupting a NF κB enhancer in a patient with recurrent macrophage activation syndrome and systemic juvenile idiopathic arthritis

Macrophage activation syndrome (MAS) is a life-threatening complication of systemic juvenile idiopathic arthritis (SJIA), and has pathologic similarity to hemophagocytic lymphohistiocytosis (HLH). Intronic variants in UNC13D are found in patients with familial HLH-3 (FHL3), but the role of non-coding variants in MAS is unknown. The objective of this study was to identify deep intronic UNC13D variants in patients with MAS. A custom enrichment library was constructed to sequence approximately 1 MB flanking UNC13D in 24 patients with SJIA, recurrent MAS, and negative prior genetic (exon/coding) testing. Functional consequences of intronic variants were assessed using quantitative PCR on patient derived peripheral blood mononuclear cells (PBMC), electrophoretic mobility shift assay (EMSA), in vitro transcriptional enhancer assays, and in vitro NK cell degranulation assays. We report a patient with SJIA and recurrent episodes of MAS, found to have a novel functional intronic variant in UNC13D, c.117+143A&gt;G. This variant occurs in a proposed regulatory region that drives an alternative, lymphocyte specific UNC13D transcript, and is associated with reduced transcript levels in patient PBMC. In support of this, the patient’s variant disrupts NFκB binding to a functional transcriptional enhancer, leading to reduced enhancer activity and NK cell degranulation in vitro. Another patient was identified with a previously described UNC13D intronic variant, for a total non-coding variant hit rate of 8.3% (2/24). These findings highlight that intronic variants in key regulatory regions may be associated with MAS in patients with SJIA, and support deep sequencing approaches when causative coding variants are not identified.

Effect of Biologic Therapy on Clinical and Laboratory Features of Macrophage Activation Syndrome Associated With Systemic Juvenile Idiopathic Arthritis

OBJECTIVE

To assess performance of the 2016 macrophage activation syndrome (MAS) classification criteria for patients with systemic juvenile idiopathic arthritis (JIA) who develop MAS while treated with biologic medications.

METHODS

A systematic literature review was performed to identify patients with MAS while being treated with interleukin (IL)-1 and IL-6 blocking agents. Clinical and laboratory information was compared to a large previously compiled historical cohort.

RESULTS

Eighteen publications were identified, and after removing duplicates, 35 patients treated with canakinumab and 49 patients with tocilizumab were available for analysis; 5 anakinra-treated patients were excluded due to limited numbers. MAS classification criteria were less likely to classify tocilizumab-treated patients as having MAS compared to the historical cohort or canakinumab-treated patients (56.7%, 78.5%, and 84%, respectively; P < 0.01). Patients who developed MAS while treated with canakinumab trended towards lower ferritin at MAS onset than the historical cohort (4,050 versus 5,353 ng/ml; P = 0.18) but had no differences in other cardinal clinical or laboratory features. In comparison, patients who developed MAS while treated with tocilizumab were less likely febrile and had notably lower ferritin levels (1,152 versus 5,353 ng/ml; P < 0.001). Other features of MAS were more pronounced in patients treated with tocilizumab, including lower platelet counts, lower fibrinogen, and higher aspartate aminotransferase levels. Mortality rates for patients with MAS treated with tocilizumab or canakinumab were not significantly different from the historical cohort.

CONCLUSION

These findings show substantial alterations in MAS features that may limit utility of defined criteria for diagnosis of systemic JIA patients treated with biologic agents.

MicroRNA networks associated with active systemic juvenile idiopathic arthritis regulate CD163 expression and anti-inflammatory functions in macrophages through two distinct mechanisms

Systemic juvenile idiopathic arthritis (SJIA) is a severe childhood arthropathy with features of autoinflammation. Monocytes and macrophages in SJIA have a complex phenotype with both pro- and anti-inflammatory properties that combine features of several well characterized in vitro conditions used to activate macrophages. An important anti-inflammatory phenotype is expression of CD163, a scavenger receptor that sequesters toxic pro-inflammatory complexes that is highly expressed in both active SJIA and macrophage activation syndrome (MAS). CD163 is most strongly up-regulated by IL-10 (M(IL-10)), and not by other conditions that reflect features seen in SJIA monocytes such as M(LPS+IC). MicroRNA plays key roles in integrating cellular signals such as those in macrophage polarization, and as such we hypothesize microRNAs regulate macrophage functional responses in SJIA including CD163 expression. We find that 2 microRNAs previously found to be elevated in active SJIA, miR-125a-5p and miR-181c, significantly reduced macrophage CD163 expression through 2 distinct mechanisms. Neither microRNA was elevated in M(IL-10) with robust CD163 expression, but were instead induced in M(LPS+IC) where they restricted CD163 mRNA expression. Mir-181 species directly targeted CD163 mRNA for degradation. In contrast, miR-125a-5p functions indirectly, as transcriptome analysis of miR-125a-5p overexpression identified "cytokine-cytokine receptor interactions" as the most significantly repressed gene pathway, including decreased IL10RA, required for IL-10-mediated CD163 expression. Finally, overexpression of miR-181c inhibited CD163 anti-inflammatory responses to hemoglobin or high mobility group box 1 (HMGB1) complexes. Together, these data show that microRNA utilizes multiple mechanisms to integrate well-characterized polarization phenotypes and regulate macrophage functional properties seen in SJIA.

Urine S100 proteins as potential biomarkers of lupus nephritis activity

Background

Improved, noninvasive biomarkers are needed to accurately detect lupus nephritis (LN) activity. The purpose of this study was to evaluate five S100 proteins (S100A4, S100A6, S100A8/9, and S100A12) in both serum and urine as potential biomarkers of global and renal system-specific disease activity in childhood-onset systemic lupus erythematosus (cSLE).

Methods

In this multicenter study, S100 proteins were measured in the serum and urine of four cSLE cohorts and healthy control subjects using commercial enzyme-linked immunosorbent assays. Patients were divided into cohorts on the basis of biospecimen availability: (1) longitudinal serum, (2) longitudinal urine, (3) cross-sectional serum, and (4) cross-sectional urine. Global and renal disease activity were defined using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) and the SLEDAI-2K renal domain score. Nonparametric testing was used for statistical analysis, including the Wilcoxon signed-rank test, Kruskal-Wallis test, Mann-Whitney U test, and Spearman’s rank correlation coefficient.

Results

All urine S100 proteins were elevated in patients with active LN compared with patients with active extrarenal disease and healthy control subjects. All urine S100 protein levels decreased with LN improvement, with S100A4 demonstrating the most significant decrease. Urine S100A4 levels were also higher with proliferative LN than with membranous LN. S100A4 staining in the kidney localized to mononuclear cells, podocytes, and distal tubular epithelial cells. Regardless of the S100 protein tested, serum levels did not change with cSLE improvement.

Conclusions

Higher urine S100 levels are associated with increased LN activity in cSLE, whereas serum S100 levels do not correlate with disease activity. Urine S100A4 shows the most promise as an LN activity biomarker, given its pronounced decrease with LN improvement, isolated elevation in urine, and positive staining in resident renal cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1444-4) contains supplementary material, which is available to authorized users.

Transcriptional profiles of JIA patient blood with subsequent poor response to methotrexate

Objective

The mechanisms that determine the efficacy or inefficacy of MTX in JIA are ill-defined. The objective of this study was to identify a gene expression transcriptional signature associated with poor response to MTX in patients with JIA.

Methods

RNA sequencing was used to measure gene expression in peripheral blood mononuclear cells collected from 47 patients with JIA prior to MTX treatment and 14 age-matched controls. Differentially expressed baseline genes between responders and non-responders were evaluated. Biological differences between all JIA patients and controls were explored by constructing a signature of differentially expressed genes. Unsupervised clustering and pathway analysis was performed.

Results

A signature of 99 differentially expressed genes (Bonferroni-corrected P < 0.05) capturing the biological differences between all JIA patients and controls was identified. Unsupervised clustering of samples based on this list of 99 genes produced subgroups enriched for MTX response status. Comparing this gene signature with reference signatures from sorted cell populations revealed high concordance between the expression signatures of monocytes and of MTX non-responders. CXCL8 (IL-8) was the most significantly differentially expressed gene transcript comparing all JIA patients with controls (Bonferroni-corrected P = 4.12 × 10-10).

Conclusion

Variability in clinical response to MTX in JIA patients is associated with differences in gene transcripts modulated in monocytes. These gene expression profiles may provide a basis for biomarkers predictive of treatment response.

Monocyte MicroRNA Expression in Active Systemic Juvenile Idiopathic Arthritis Implicates MicroRNA-125a-5p in Polarized Monocyte Phenotypes

OBJECTIVE

Systemic juvenile idiopathic arthritis (JIA) is an inflammatory disease of childhood in which cells of the monomyelocytoid lineage are thought to be key effector cells. Monocytes from patients with systemic JIA have a distinct phenotype, with features of both M1 and M2 alternative activation. MicroRNAs are critical regulators of monocyte polarization and function, but cellular microRNAs in systemic JIA have not been examined systematically.

METHODS

MicroRNA TaqMan arrays were used to determine the expression profiles of monocytes from children with systemic JIA. Expression of microRNA-125a-5p (miR-125a-5p) and its contribution to monocyte polarization were examined using in vitro-polarized THP-1 cells and primary human monocytes.

RESULTS

A total of 110 microRNAs were found to be differentially expressed in monocytes from patients with active systemic JIA, including molecules implicated in rheumatoid arthritis pathogenesis, cytokine production, and monocyte polarization. MicroRNA-125a-5p was identified as being highly up-regulated in monocytes from children with active systemic JIA, as compared to those from children with clinically inactive JIA or those with active polyarticular JIA, and correlated with systemic features of the disease. In vitro, monocyte miR125a-5p expression was increased after polarization under M2b or M2c conditions. Inhibition of miR-125a-5p showed that this microRNA contributed to full polarization of M2b regulatory macrophages. In contrast, miR-125a-5p overexpression enhanced M2b polarization and altered other polarized populations, including increasing the production of M2 markers. Indeed, in vitro overexpression of this microRNA altered the macrophage phenotype toward that observed in systemic JIA.

CONCLUSION

Children with active systemic JIA have profound alterations in the expression of microRNAs that are implicated in monocyte function and polarization. One of these microRNAs, miR-125a-5p, is also a regulator of immunoregulatory M2b macrophages.

Proinflammatory Cytokine Environments Can Drive Interleukin-17 Overexpression by γ/δ T Cells in Systemic Juvenile Idiopathic Arthritis

OBJECTIVE

Systemic-onset juvenile idiopathic arthritis (JIA) is speculated to follow a biphasic course, with an initial systemic disease phase driven by innate immune mechanisms and interleukin-1β (IL-1β) as a key cytokine and a second chronic arthritic phase that may be dominated by adaptive immunity and cytokines such as IL-17A. Although a recent mouse model points to a critical role of IL-17-expressing γ/δ T cells in disease pathology, in humans, both the prevalence of IL-17 and the role of IL-17-producing cells are still unclear.

METHODS

Serum samples from systemic JIA patients and healthy pediatric controls were analyzed for the levels of IL-17A and related cytokines. Whole blood samples were studied for cellular expression of IL-17 and interferon-γ (IFNγ). CD4+ and γ/δ T cells isolated from the patients and controls were assayed for cytokine secretion in different culture systems.

RESULTS

IL-17A was prevalent in sera from patients with active systemic JIA, while both ex vivo and in vitro experiments revealed that γ/δ T cells overexpressed this cytokine. This was not seen with CD4+ T cells, which expressed strikingly low levels of IFNγ. Therapeutic IL-1 blockade was associated with partial normalization of both cytokine expression phenotypes. Furthermore, culturing healthy donor γ/δ T cells in serum from systemic JIA patients or in medium spiked with IL-1β, IL-18, and S100A12 induced IL-17 overexpression at levels similar to those observed in the patients' cells.

CONCLUSION

A systemic JIA cytokine environment may prime γ/δ T cells in particular for IL-17A overexpression. Thus, our observations in systemic JIA patients strongly support a pathophysiologic role of these cells, as proposed by the recent murine model.

Genetic architecture distinguishes systemic juvenile idiopathic arthritis from other forms of juvenile idiopathic arthritis: clinical and therapeutic implications

OBJECTIVES

Juvenile idiopathic arthritis (JIA) is a heterogeneous group of conditions unified by the presence of chronic childhood arthritis without an identifiable cause. Systemic JIA (sJIA) is a rare form of JIA characterised by systemic inflammation. sJIA is distinguished from other forms of JIA by unique clinical features and treatment responses that are similar to autoinflammatory diseases. However, approximately half of children with sJIA develop destructive, long-standing arthritis that appears similar to other forms of JIA. Using genomic approaches, we sought to gain novel insights into the pathophysiology of sJIA and its relationship with other forms of JIA.

METHODS

We performed a genome-wide association study of 770 children with sJIA collected in nine countries by the International Childhood Arthritis Genetics Consortium. Single nucleotide polymorphisms were tested for association with sJIA. Weighted genetic risk scores were used to compare the genetic architecture of sJIA with other JIA subtypes.

RESULTS

The major histocompatibility complex locus and a locus on chromosome 1 each showed association with sJIA exceeding the threshold for genome-wide significance, while 23 other novel loci were suggestive of association with sJIA. Using a combination of genetic and statistical approaches, we found no evidence of shared genetic architecture between sJIA and other common JIA subtypes.

CONCLUSIONS

The lack of shared genetic risk factors between sJIA and other JIA subtypes supports the hypothesis that sJIA is a unique disease process and argues for a different classification framework. Research to improve sJIA therapy should target its unique genetics and specific pathophysiological pathways.

Early changes in gene expression and inflammatory proteins in systemic juvenile idiopathic arthritis patients on canakinumab therapy

Background

Canakinumab is a human anti-interleukin-1β (IL-1β) monoclonal antibody neutralizing IL-1β-mediated pathways. We sought to characterize the molecular response to canakinumab and evaluate potential markers of response using samples from two pivotal trials in systemic juvenile idiopathic arthritis (SJIA).

Methods

Gene expression was measured in patients with febrile SJIA and in matched healthy controls by Affymetrix DNA microarrays. Transcriptional response was assessed by gene expression changes from baseline to day 3 using adapted JIA American College of Rheumatology (aACR) response criteria (50 aACR JIA). Changes in pro-inflammatory cytokines IL-6 and IL-18 were assessed up to day 197.

Results

Microarray analysis identified 984 probe sets differentially expressed (≥2-fold difference; P < 0.05) in patients versus controls. Over 50% of patients with ≥50 aACR JIA were recognizable by baseline expression values. Analysis of gene expression profiles from patients achieving ≥50 aACR JIA response at day 15 identified 102 probe sets differentially expressed upon treatment (≥2-fold difference; P < 0.05) on day 3 versus baseline, including IL-1β, IL-1 receptors (IL1-R1 and IL1-R2), IL-1 receptor accessory protein (IL1-RAP), and IL-6. The strongest clinical response was observed in patients with higher baseline expression of dysregulated genes and a strong transcriptional response on day 3. IL-6 declined by day 3 (≥8-fold decline; P < 0.0001) and remained suppressed. IL-18 declined on day 57 (≥1.5-fold decline, P ≤ 0.002).

Conclusions

Treatment with canakinumab in SJIA patients resulted in downregulation of innate immune response genes and reductions in IL-6 and clinical symptoms. Additional research is needed to investigate potential differences in the disease mechanisms in patients with heterogeneous gene transcription profiles.

Trial registration

Clinicaltrials.gov: NCT00886769 (trial 1). Registered on 22 April 2009; NCT00889863 (trial 2). Registered on 21 April 2009.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1212-x) contains supplementary material, which is available to authorized users.

Systemic onset juvenile idiopathic arthritis and exposure to fine particulate air pollution

OBJECTIVES

Fine particulate matter (PM2.5) is a measurable component of ambient pollution, and positive associations of short-term PM2.5 exposure with the clinical presentation of systemic onset juvenile idiopathic arthritis (SJIA) in young children have been described in a regional cohort. Our objective was to further establish associations between short-term pollution exposures and the reported clinical event of SJIA onset in cases residing from multiple metropolitan regions.

METHODS

A case-crossover study design was used to analyse associations of short-term PM2.5 exposures with the event of SJIA symptom onset from cases residing in five metropolitan regions. Time trends, seasonality, month, and weekday were controlled for by matching. Selected exposure windows (to 14 days) of PM2.5 were examined.

RESULTS

Positive, statistically significant associations between PM2.5 concentrations and elevated risk of SJIA were not observed. The most positive associations of short-term PM2.5 exposure with SJIA were in children <5.5 years (RR 1.75, 95% CI 0.85-3.62). An ad hoc extended pooled analysis including previously reported cases from Utah's metropolitan areas identified an increased risk of SJIA for children <5.5 years (RR = 1.76, 95% CI 1.07-2.89 per 10 μg/m3 increase in 3-day lagged moving average PM2.5).

CONCLUSIONS

In this multi-city, multi-period study small, statistically insignificant PM2.5-SJIA associations are observed. However, as found in prior study, the PM2.5-SJIA association is most suggestive in preschool aged children. Larger numbers of SJIA cases spatially located in geographic areas which experience a greater day to day ambient particulate burden may be required by the analysis to demonstrate effects.

Proceedings of the 2016 Childhood Arthritis and Rheumatology Research Alliance (CARRA) Scientific Meeting : Toronto, Canada. 14-17 April 2016

P1 Serologic evidence of gut-driven systemic inflammation in juvenile idiopathic arthritis Lampros Fotis, Nur Shaikh, Kevin Baszis, Anthony French, Phillip Tarr P2 Oral health and anti-citrullinated peptide antibodies (ACPA) in juvenile idiopathic arthritis Sriharsha Grevich, Peggy Lee, Sarah Ringold, Brian Leroux, Hannah Leahey, Megan Yuasa, Jessica Foster, Jeremy Sokolove, Lauren Lahey, William Robinson, Joshua Newsom, Anne Stevens P3 Novel autoantigens for endothelial cell antibodies in pediatric rheumatic diseases identified by proteomics Rie Karasawa, Mayumi Tamaki, Megumi Tanaka, Toshiko Sato, Kazuo Yudoh, James N. Jarvis P4 Transcriptional profiling reveals monocyte signature associated with JIA patient poor response to methotrexate Halima Moncrieffe, Mark F. Bennett, Monica Tsoras, Lorie Luyrink, Huan Xu, Sampath Prahalad, Paula Morris, Jason Dare, Peter A. Nigrovic, Margalit Rosenkranz, Mara Becker, Kathleen M. O’Neil, Thomas Griffin, Daniel J. Lovell, Alexei A. Grom, Mario Medvedovic, Susan D. Thompson P5 A multi-dimensional genomic map for polyarticular juvenile idiopathic arthritis Lisha Zhu, Kaiyu Jiang, Laiping Wong, Michael J Buck, Yanmin Chen, Halima Moncrieffe, Laura Brungs, Tao Liu, Ting Wang, James N Jarvis P6 Tocilizumab for treatment of children with refractory JIA Khaled Alsaeid, Jasim Alfailakawi, Hamid Alenezi, Hazim Alsaeed P7 Clinical characteristics of the initial patients enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry Tim Beukelman, Marc Natter, Norm Ilowite, Kelly Mieszkalski, Grendel Burrell, Brian Best, Helen Bristow, Shannon Carr, Anne Dennos, Rachel Kaufmann, Yukiko Kimura, Laura Schanberg P8 Comparative performance of small and large clinical centers in a comprehensive pediatric rheumatology disease registry Peter R Blier P9 Clinical characteristics of children with membranous lupus nephritis: The Childhood Arthritis and Rheumatology Research Alliance Legacy Registry Alexis Boneparth, Scott E. Wenderfer, L. Nandini Moorthy, Suhas M. Radhakrishna, Anna Carmela P. Sagcal-Gironella, Emily von Scheven P10 Rituximab use in pediatric lupus anticoagulant hypoprothrombinemia syndrome - a two center experience Kader Cetin Gedik, Salma Siddique, Cassyanne L. Aguiar, Doruk Erkan P11 Predictors of complementary and alternative medicine use and response in children with musculoskeletal conditions Ezra Cohen, Yvonne Lee, Michelle Dossett, Darshan Mehta, Roger Davis P12 Comparison of pediatric rheumatology and nephrology survey results for the treatment of refractory proliferative lupus nephritis and renal flare in juvenile SLE Mileka Gilbert, Beatrice Goilav, Esra Meidan, Joyce Hsu, Alexis Boneparth, Anabelle Chua, Stacy Ardoin, Scott E. Wenderfer, Emily Von Scheven, Natasha M. Ruth P13 Transitioning lupus patients from pediatric to adult rheumatology Joyce Hui-Yuen, Kader Cetin Gedik, Liza Bermudez, Ashlea Cook, Lisa Imundo, Amy Starr, Andrew Eichenfield, Anca Askanase P14 The systemic juvenile idiopathic arthritis cohort of the Childhood Arthritis & Rheumatology Research Alliance Registry Ginger Janow, Laura E. Schanberg, Soko Setoguchi, Victor Hasselblad, Elizabeth D. Mellins, Rayfel Schneider, Yukiko Kimura, The CARRA Legacy Registry Investigators P15 Results of the pilot study of the Childhood Arthritis and Rheumatology Research Alliance (CARRA) consensus treatment plans for new-onset systemic juvenile idiopathic arthritis Yukiko Kimura, Sriharsha Grevich, Timothy Beukelman, Esi Morgan, T Brent Graham, Maria Ibarra, Yonit Sterba Ruas, Marisa Klein-Gitelman, Karen Onel, Sampath Prahalad, Marilynn Punaro, Sarah Ringold, Dana Toib, Heather Van Mater, Jennifer E. Weiss, Pamela F. Weiss, Kelly Mieszkalski, Laura E. Schanberg P16 A systemic review of pain relief modalities in juvenile idiopathic arthritis: First step in developing a novel decision support intervention Timothy S. H. Kwok, Jacinthe Bisaillon, Christine Smith, Lucie Brosseau, Jennifer Stinson, Adam M. Huber, Ciaran M. Duffy, Karine Toupin April P17 Barriers and facilitators to care retention for pediatric systemic lupus erythematous patients in South Africa: A qualitative study Laura B Lewandowski, Christiaan Scott P18 Evaluating the feasibility of conducting comparative effectiveness studies in juvenile Localized Scleroderma (jLS) Suzanne C. Li, Kathryn S. Torok, C. Egla Rabinovich, Sandy D. Hong, Mara L Becker, Fatma Dedeoglu, Maria F. Ibarra, Polly J Ferguson, Rob C. Fuhbrigge, Katie G. Stewart, Elena Pope, Ronald M. Laxer, Thomas G. Mason, Gloria C. Higgins, Xiaohu Li, Marilynn G. Punaro, George Tomlinson, Eleanor Pullenayegum, John Matelski, Laura Schanberg, Brian M. Feldman P19 Tonsillar histology in patients with periodic fever, aphthous stomatitis, pharyngitis, adenitis (PFAPA) syndrome Kalpana Manthiram, Hernan Correa, Kathryn Edwards P20 Clinical course of juvenile dermatomyositis presenting as skin predominant disease Edward J. Oberle, Michelle Bayer, Dominic O. Co, Hatice Ezgi Baris, Yvonne Chiu, Adam Huber, Susan Kim P21 A Survey of musculoskeletal ultrasound practices of pediatric rheumatologists in North America Edward J Oberle, Timothy Beukelman P22 Assessment, classification and treatment of calcinosis as a complication of juvenile dermatomyositis: A survey of pediatric rheumatologists by the Childhood Arthritis and Rheumatology Research Alliance Amir B. Orandi, Kevin W. Baszis, Vikas Dharnidharka, Mark F. Hoeltzel, for the CARRA JDM Committee P23 CARRA dermatomyositis CTP pilot study Ann Reed, Adam Huber, George Tomlinson, Eleanor Pullenayegum, John Matelski, Y. Ingrid Goh, Laura Schanberg, Brian M. Feldman P24 Unexpectedly high incidences and prolonged disease activity in children with chronic non-bacterial osteomyelitis (CNO) as compared to bacterial osteomyelitis Anja Schnabel, Ursula Range, Gabriele Hahn, Timo Siepmann, Reinhard Berner, Christian Michael Hedrich P25 Juvenile systemic sclerosis cohort within the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Legacy Registry: Follow up characteristics Brandi Stevens, Kathryn S. Torok, Suzanne Li, Nicole Hershey, Megan Curran, Gloria Higgins, Katharine Moore, Egla Rabinovich, Anne M. Stevens, for the CARRA Registry Investigators P26 Development and usability testing of an iPad and desktop psycho-educational game for children with Juvenile Idiopathic Arthritis and their parents Jennifer Stinson, Mark Connelly, Adam Huber, Nadia Luca, Lynn Spiegel, Argerie Tsimicalis, Stephanie Luca, Naweed Tajuddin, Roberta Berard, Julia Barsalou, Sarah Campillo, Paul Dancey, Ciaran Duffy, Brian Feldman, Nicole Johnson, Patrick McGrath, Natalie Shiff, Shirley Tse, Lori Tucker, Charles Victor P27 iCanCope^TM: User-centred design and development of a smartphone app to support self-management for youth with arthritis pain Jennifer Stinson, Chitra Lalloo, Lauren Harris, Joseph Cafazzo, Lynn Spiegel, Brian Feldman, Nadia Luca, Ronald Laxer P28 Accessing pediatric rheumatology care: Despite barriers, few parents prefer telemedicine Danielle R. Bullock, Richard K. Vehe, Lei Zhang, Colleen K. Correll¹ P29 Exploration of factors contributing to time to achieve clinically inactive disease (CID) in juvenile idiopathic arthritis (JIA): A preliminary report Suhas Ganguli, Max Shenberger, Ritesh Korumilli, Beth Gottlieb P30 Pediatric rheumatology referral patterns: Presenting complaints of new patients at a large, urban academic center Martha Rodriguez, Deirdre de Ranieri, Karen Onel, Linda Wagner-Weiner, Melissa Tesher P31 Quality improvement (QI) initiatives in childhood systemic lupus erythematosus (cSLE) Elizabeth Roth Wojcicki, Kristyn L. Maletta, Dominic O. Co, Marsha Malloy, Sarah Thomson, Judyann C. Olson P32 Proliferative lupus nephritis in juvenile SLE: Support from the pediatric nephrology community for the definitions of responsiveness and flare in the 2012 consensus treatment plans Scott E. Wenderfer, Mileka Gilbert, Joyce Hsu, Sangeeta Sule, Tamar B. Rubinstein, Beatrice Goilav, Daryl M. Okamura, Annabelle Chua, Laurence A. Greenbaum, Jerome C. Lane, Emily von Scheven, Stacy P. Ardoin, Natasha M. Ruth P33 The steroid taper app: Making of a mobile app Jennifer M. P. Woo, Marsha M. Malloy, James A. Jegers, Dustin J. Hahn, Mary K. Hintermeyer, Stacey M. Martinetti, Gretchen R. Heckel, Elizabeth L. Roth-Wojcicki, Dominic O. Co

2016 Classification Criteria for Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis: A European League Against Rheumatism/American College of Rheumatology/Paediatric Rheumatology International Trials Organisation Collaborative Initiative

To develop criteria for the classification of macrophage activation syndrome (MAS) in patients with systemic juvenile idiopathic arthritis (JIA). A multistep process, based on a combination of expert consensus and analysis of real patient data, was conducted. A panel of 28 experts was first asked to classify 428 patient profiles as having or not having MAS, based on clinical and laboratory features at the time of disease onset. The 428 profiles comprised 161 patients with systemic JIA-associated MAS and 267 patients with a condition that could potentially be confused with MAS (active systemic JIA without evidence of MAS, or systemic infection). Next, the ability of candidate criteria to classify individual patients as having MAS or not having MAS was assessed by evaluating the agreement between the classification yielded using the criteria and the consensus classification of the experts. The final criteria were selected in a consensus conference. Experts achieved consensus on the classification of 391 of the 428 patient profiles (91.4%). A total of 982 candidate criteria were tested statistically. The 37 best-performing criteria and 8 criteria obtained from the literature were evaluated at the consensus conference. During the conference, 82% consensus among experts was reached on the final MAS classification criteria. In validation analyses, these criteria had a sensitivity of 0.73 and a specificity of 0.99. Agreement between the classification (MAS or not MAS) obtained using the criteria and the original diagnosis made by the treating physician was high (κ=0.76). We have developed a set of classification criteria for MAS complicating systemic JIA and provided preliminary evidence of its validity. Use of these criteria will potentially improve understanding of MAS in systemic JIA and enhance efforts to discover effective therapies, by ensuring appropriate patient enrollment in studies.

Elevated circulating levels of interferon-γ and interferon-γ-induced chemokines characterise patients with macrophage activation syndrome complicating systemic juvenile idiopathic arthritis

OBJECTIVES

Interferon-γ (IFNγ) is the pivotal mediator in murine models of primary haemophagocytic lymphohistiocytosis (pHLH). Given the similarities between primary and secondary HLH (sec-HLH), including macrophage activation syndrome (MAS), we investigate the involvement of the IFNγ pathway in MAS by evaluating levels of IFNγ and of the induced chemokines, and their relation with laboratory parameters of MAS in systemic juvenile idiopathic arthritis (sJIA) patients with MAS and in a murine MAS model.

METHODS

The Luminex multiplexing assay was used to assess serum levels of interleukin (IL)-1β, IL-6, IFNγ and of the IFNγ-induced chemokines CXCL9, CXCL10 and CXCL11 in patients with sec-HLH (n=11) and in patients with sJIA (n=54), of whom 20 had active MAS at sampling. Expression of IFNγ-induced chemokines was assessed in IL-6 transgenic mice in which MAS is induced by TLR4 stimulation with lipopolysaccharide.

RESULTS

Levels of IFNγ and of IFNγ-induced chemokines were markedly elevated during active MAS and sec-HLH and were significantly higher in patients with MAS compared with active sJIA without MAS. Levels in patients with active sJIA without MAS were comparable to those of patients with clinically inactive sJIA. During MAS, ferritin and alanine transferase levels and neutrophil and platelet counts were significantly correlated with serum levels of IFNγ and CXCL9. In murine MAS, serum levels of ferritin were significantly correlated with mRNA levels of Cxcl9 in liver and spleen.

CONCLUSIONS

The high levels of IFNγ and of IFNγ-induced chemokines and their correlation with the severity of laboratory abnormalities of MAS suggest a pivotal role of IFNγ in MAS.

Rate and Clinical Presentation of Macrophage Activation Syndrome in Patients With Systemic Juvenile Idiopathic Arthritis Treated With Canakinumab

OBJECTIVE

In pivotal trials, canakinumab has been shown to be effective in the treatment of systemic juvenile idiopathic arthritis (JIA), but reported adverse events have included macrophage activation syndrome (MAS). This study was undertaken to assess the impact of canakinumab on MAS incidence.

METHODS

An independent MAS Adjudication Committee (MASAC), consisting of 3 of the authors, was convened, and a search of databases from clinical studies of canakinumab treatment in systemic JIA was performed using MASAC-specified adverse event terms to identify potential MAS events. These were then adjudicated as "probable MAS," "possible MAS," or "MAS unlikely," using criteria developed by the MASAC. MAS rates were expressed as numbers of cases per 100 patient-years.

RESULTS

Of 72 potential MAS cases identified, 21 events (19 with canakinumab treatment; 2 with placebo treatment) in 19 patients were adjudicated as being probable MAS and 10 events in 9 patients as being possible MAS. Systemic JIA was well controlled in the majority of canakinumab-treated patients at the time of MAS. The time period between initiation of canakinumab treatment and onset of MAS ranged from 3 to 1,358 days (median 292 days). When the rates of probable MAS events were compared between canakinumab-treated patients (2.8 per 100 patient-years) and placebo-treated patients (7.7 per 100 patient-years), the difference was not significant (-4.9 [95% confidence interval -15.6, 5.9]). There were 3 deaths due to MAS-related complications (2 in patients receiving canakinumab; 1 in a patient receiving placebo); full recovery was reported in all other patients. Infections were the most common trigger of MAS, and the clinical features of MAS were not modified by canakinumab.

CONCLUSION

Canakinumab does not have a significant effect on MAS risk or its clinical features in patients with systemic JIA. Infections are the most common trigger, and MAS occurs even in patients whose systemic JIA is well controlled with this treatment.