Objective
The idiopathic inflammatory myopathies (IIMs) are heterogeneous diseases thought to be initiated by immune activation in genetically predisposed individuals. We imputed variants from the ...ImmunoChip array using a large reference panel to fine‐map associations and identify novel associations in IIM.
Methods
We analyzed 2,565 Caucasian IIM patient samples collected through the Myositis Genetics Consortium (MYOGEN) and 10,260 ethnically matched control samples. We imputed 1,648,116 variants from the ImmunoChip array using the Haplotype Reference Consortium panel and conducted association analysis on IIM and clinical and serologic subgroups.
Results
The HLA locus was consistently the most significantly associated region. Four non‐HLA regions reached genome‐wide significance, SDK2 and LINC00924 (both novel) and STAT4 in the whole IIM cohort, with evidence of independent variants in STAT4, and NAB1 in the polymyositis (PM) subgroup. We also found suggestive evidence of association with loci previously associated with other autoimmune rheumatic diseases (TEC and LTBR). We identified more significant associations than those previously reported in IIM for STAT4 and DGKQ in the total cohort, for NAB1 and FAM167A‐BLK loci in PM, and for CCR5 in inclusion body myositis. We found enrichment of variants among DNase I hypersensitivity sites and histone marks associated with active transcription within blood cells.
Conclusion
We found novel and strong associations in IIM and PM and localized signals to single genes and immune cell types.
Juvenile dermatomyositis (JDM) is a rare, potentially life-threatening systemic autoimmune disease primarily affecting muscle and skin. Recent advances in the recognition, standardised assessment and ...treatment of JDM have been greatly facilitated by large collaborative research networks. Through these networks, a number of immunogenetic risk factors have now been defined, as well as a number of potential pathways identified in the aetio-pathogenesis of JDM. Myositis-associated and myositis-specific autoantibodies are helping to sub-phenotype JDM, defined by clinical features, outcomes and immunogenetic risk factors. Partially validated tools to assess disease activity and damage have assisted in standardising outcomes. Aggressive treatment approaches, including multiple initial therapies, as well as new drugs and biological therapies for refractory disease, offer promise of improved outcomes and less corticosteroid-related toxicity.
Although there is great interest in harnessing the immunosuppressive potential of FOXP3(+) regulatory T cells (Tregs) for treating autoimmunity, a sizeable knowledge gap exists regarding Treg fate in ...human disease. In juvenile idiopathic arthritis (JIA) patients, we have previously reported that atypical CD25(+)FOXP3(-) Treg-like cells uniquely populate the inflamed site. Intriguingly, their proportions relative to CD25(+)FOXP3(+) Tregs associate with arthritis course, suggesting a role in disease. The ontogeny of these FOXP3(-) Treg-like cells is, however, unknown. In this study, we interrogated clonal relationships between CD4(+) T cell subsets in JIA, using high-throughput TCR repertoire analysis. We reveal that FOXP3(+) Tregs possess highly exclusive TCRβ usage from conventional T cells, in blood, and also at the inflamed site, where they are clonally expanded. Intriguingly, the repertoires of FOXP3(+) Tregs in synovial fluid are highly overlapping with CD25(+)FOXP3(-) Treg-like cells, indicating fluctuations in FOXP3 expression in the inflamed joint. Furthermore, cultured synovial Tregs rapidly downregulated FOXP3 protein (but not mRNA), and this process was prevented by addition of synovial fluid from JIA patients, through an IL-6-independent mechanism. Our findings suggest that most Tregs arise from a separate lineage from conventional T cells, and that this repertoire divergence is largely maintained under chronic inflammatory conditions. We propose that subsequent Treg expansions at the inflamed site creates an environment that leads to competition for limited resources within the synovium, resulting in the destabilization of FOXP3 expression in some Tregs.
Background: Juvenile idiopathic arthritis (JIA) consists of a heterogeneous group of disorders with, for the most part, an unknown immunopathogenesis. Although onset and disease course differ, the ...subtypes of JIA share the occurrence of chronic inflammation of the joints, with infiltrations of immunocompetent cells that secrete inflammatory mediators. Objective: To identify a panel of cytokines specifically related to the inflammatory process in JIA. Methods: Using a new technology, the multiplex immunoassay, 30 cytokines were measured in plasma of 65 patients with JIA, of which 34 were paired with synovial fluid. These data were compared with plasma of 20 healthy controls and 9 patients with type I diabetes, a chronic inflammatory disease. Results: Patients with JIA had, irrespective of their subclassification, significantly higher levels of tumour necrosis factor α, macrophage inhibitory factor (MIF), CCL2, CCL3, CCL11, CCL22 and CXCL9 in plasma than controls. In paired plasma and synovial fluid samples of patients with JIA, significantly higher levels of interleukin (IL)6, IL15, CCL2, CCL3, CXCL8, CXCL9 and CXCL10 were present in synovial fluid. Cluster analysis in all patients with JIA revealed a predominant pro-inflammatory cytokine cluster during active disease and a regulatory/anti-inflammatory-related cytokine cluster during remission. Whether a discrimination profile of various cytokines could help in the determination of disease classification was tested. Conclusion: It is suggested that several cytokines (IL18, MIF, CCL2, CCL3, CCL11, CXCL9 and CXCL10) may correspond to the activation status during inflammation in JIA and could be instrumental in monitoring disease activity and outcomes of (new) immunotherapies.
Intrinsic complement C3 activity is integral to human T helper type 1 (Th1) and cytotoxic T cell responses. Increased or decreased intracellular C3 results in autoimmunity and infections, ...respectively. The mechanisms regulating intracellular C3 expression remain undefined. We identified complement, including C3, as among the most significantly enriched biological pathway in tissue-occupying cells. We generated C3-reporter mice and confirmed that C3 expression was a defining feature of tissue-immune cells, including T cells and monocytes, occurred during transendothelial diapedesis, and depended on integrin lymphocyte-function-associated antigen 1 (LFA-1) signals. Immune cells from patients with leukocyte adhesion deficiency type 1 (LAD-1) had reduced C3 transcripts and diminished effector activities, which could be rescued proportionally by intracellular C3 provision. Conversely, increased C3 expression by T cells from arthritis patients correlated with disease severity. Our study defines integrins as key controllers of intracellular complement, demonstrates that perturbations in the LFA-1-C3-axis contribute to primary immunodeficiency, and identifies intracellular C3 as biomarker of severity in autoimmunity.
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•Diapedesis induces C3 expression as a feature of immune cells in tissue•C3 transcription is LFA-1 dependent and integral to normal immune cell activity•Defective C3 expression underlies human primary immune deficiency disease LAD-1•The integrin network is a key driver of complosome activity and cell function
Intracellular complement C3 regulates human immune cell responses, but how C3 levels are controlled remains undefined. Kolev et al. demonstrate that C3 gene expression is a cardinal feature of immune cells in tissues. C3 transcription depends on integrin LFA-1 signals and diminished “C3 licensing” in LFA-1-deficient patients contributes to their compromised immunity, revealing integrins as key controllers of intracellular complement.
Analysis of myeloid-related protein 8 and 14 complex (MRP8/14) serum concentrations is a potential new tool to support the diagnosis of systemic-onset juvenile idiopathic arthritis (SJIA) in the ...presence of fever of unknown origin.
To test the ability of MRP8/14 serum concentrations to monitor disease activity in patients with SJIA and stratify patients at risk of relapse.
Serum concentrations of MRP8/14 in 52 patients with SJIA were determined by a sandwich ELISA. The monitoring of therapeutic regimens targeting interleukin 1 and tumour necrosis factor α, and methotrexate treatment was analysed and diagnostic power to predict flares was tested.
MRP8/14 levels were clearly raised in active disease and decreased significantly in response to successful treatments. Serum concentrations of MRP8/14 increased significantly (p<0.001) (mean±95% CI 12.030±3.090 ng/ml) during disease flares compared with patients with inactive disease (864±86 ng/ml). During clinical remission MRP8/14 serum levels of >740 ng/ml predicted disease flares accurately (sensitivity 92%, specificity 88%). MRP8/14 levels correlated well with clinical disease activity, as assessed by physician's global assessment of disease activity (r=0.62), Childhood Health Assessment Questionnaire (r=0.56), active joint count (r=0.46) and with C-reactive protein (r=0.71) and erythrocyte sedimentation rate (r=0.72) (for all p<0.001).
MRP8/14 serum concentrations correlate closely with response to drug treatment and disease activity and therefore might be an additional measurement for monitoring anti-inflammatory treatment of individual patients with SJIA. MRP8/14 serum concentrations are the first predictive biomarker indicating subclinical disease activity and stratifying patients at risk of relapse during times of clinically inactive disease.
Objective
Granulocyte–macrophage colony stimulating factor (GM‐CSF) is a potent inflammatory mediator that is responsible for recruitment and activation of innate immune cells. Recent data from ...murine studies have identified Th17 cells as a key source of GM‐CSF and suggest that T cell–derived GM‐CSF is instrumental in the induction of autoimmune disease. The present study was undertaken to analyze the expression of T cell–derived GM‐CSF in the joints of patients with juvenile idiopathic arthritis (JIA) and to investigate the differentiation of Th17 cells and how this relates to GM‐CSF+ T helper cells.
Methods
Synovial fluid (SF) and peripheral blood (PB) samples from 24 patients with JIA were analyzed, by flow cytometry and reverse transcription–polymerase chain reaction, for expression of GM‐CSF and the Th17 marker CD161. A cytokine capture assay was used to purify Th17 cells and test the plasticity of cytokine production in response to interleukin‐12 (IL‐12) and IL‐23.
Results
The frequency of GM‐CSF–producing T helper cells was significantly enriched in SF mononuclear cells compared to PB mononuclear cells from the patients with JIA (24.1% of CD4+ T cells versus 2.9%) and closely correlated with the erythrocyte sedimentation rate (r2 = 0.91, P < 0.001). Synovial GM‐CSF+ T cells were predominantly CD161+ and coexpressed interferon‐γ (IFNγ), but not IL‐17. Culture of Th17 cells in the presence of IL‐12 led to rapid up‐regulation of GM‐CSF and IFNγ, recapitulating the phenotype of GM‐CSF–expressing cells within the joint.
Conclusion
Our results identify a novel outcome of Th17 plasticity in humans that may account for the enrichment of GM‐CSF–expressing T cells in the joints of patients with JIA. The association of GM‐CSF expression with systemic inflammation highlights the potential role of Th17‐related cytokines in the pathology of JIA.
Abstract
Objectives
To determine if depressive symptoms assessed near diagnosis associate with future measures of pain, disability and disease for adolescent patients diagnosed with JIA.
Methods
Data ...were analysed from JIA patients aged 11-16 years recruited to the Childhood Arthritis Prospective Study, a UK-based inception cohort of childhood-onset arthritis. Depressive symptoms (using the Mood and Feelings Questionnaire; MFQ), active and limited joint count, disability score (Childhood Health Assessment Questionnaire), pain visual analogue scale and patient's general evaluation visual analogue scale were collected. Associations between baseline measures (first visit to paediatric rheumatologist) were analysed using multiple linear regression. Linear mixed-effect models for change in the clinical measures of disease over 48 months were estimated including MFQ as an explanatory variable.
Results
Data from 102 patients were analysed. At baseline, median (IQR) age was 13.2 years (11.9-14.2 years) and 14.7% scored over the MFQ cut-off for major depressive disorder. At baseline, depressive symptoms significantly associated with all clinical measures of disease (P ⩽ 0.01). High baseline depressive symptoms scores predicted worse pain (P ⩽ 0.005) and disability (P ⩽ 0.001) 12 months later but not active and limited joint counts.
Conclusions
Adolescent patients with JIA and depressive symptoms had more active joints, pain and disability at the time of their first specialist appointment. The associations between baseline depression and both pain and disability continued for at least one year, however, this was not the case for active joint count.
Granulocyte-macrophage colony stimulating factor (GM-CSF) is a potent inflammatory mediator that is responsible for recruitment and activation of innate immune cells. Recent data from murine studies ...have identified Th17 cells as a key source of GM-CSF and suggest that T cell-derived GM-CSF is instrumental in the induction of autoimmune disease. The present study was undertaken to analyze the expression of T cell-derived GM-CSF in the joints of patients with juvenile idiopathic arthritis (JIA) and to investigate the differentiation of Th17 cells and how this relates to GM-CSF+ T helper cells.
Synovial fluid (SF) and peripheral blood (PB) samples from 24 patients with JIA were analyzed, by flow cytometry and reverse transcription-polymerase chain reaction, for expression of GM-CSF and the Th17 marker CD161. A cytokine capture assay was used to purify Th17 cells and test the plasticity of cytokine production in response to interleukin-12 (IL-12) and IL-23.
The frequency of GM-CSF-producing T helper cells was significantly enriched in SF mononuclear cells compared to PB mononuclear cells from the patients with JIA (24.1% of CD4+ T cells versus 2.9%) and closely correlated with the erythrocyte sedimentation rate (r(2) = 0.91, P < 0.001). Synovial GM-CSF+ T cells were predominantly CD161+ and coexpressed interferon-γ (IFNγ), but not IL-17. Culture of Th17 cells in the presence of IL-12 led to rapid up-regulation of GM-CSF and IFNγ, recapitulating the phenotype of GM-CSF-expressing cells within the joint.
Our results identify a novel outcome of Th17 plasticity in humans that may account for the enrichment of GM-CSF-expressing T cells in the joints of patients with JIA. The association of GM-CSF expression with systemic inflammation highlights the potential role of Th17-related cytokines in the pathology of JIA.
The ectonucleotidase CD39 has recently been described as being highly expressed on regulatory Foxp3(+) CD4 T cells. Through hydrolysis of proinflammatory extracellular ATP, CD39 activity represents a ...newly described mechanism of regulatory T cell action. We report a novel population of human CD4 T cells that express CD39 yet are Foxp3 negative. These cells produce the proinflammatory cytokines IFN-gamma and IL-17 and fail to suppress proliferation; however, they still have high ATP hydrolysis activity. In the inflammatory site in human juvenile idiopathic arthritis, the CD39(+)Foxp3(-) population is greatly increased compared with peripheral blood of patients or healthy controls. We also show that cells expressing the AMPase CD73 are less frequent in the joint than in blood. To our knowledge, this is the first study to describe and characterize CD39 function on CD4 T cells from the target site in a human autoinflammatory condition. Our data suggest that in human CD4(+) T cells from the inflamed site, CD39 can be highly expressed on two populations, one regulatory and the other of a memory phenotype.
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