Genome-scale case-control analysis of CD4+ T-cell DNA methylation in juvenile idiopathic arthritis reveals potential targets involved in disease

BACKGROUND: Juvenile Idiopathic Arthritis (JIA) is a complex autoimmune rheumatic disease of largely unknown cause. Evidence is growing that epigenetic variation, particularly DNA methylation, is associated with autoimmune disease. However, nothing is currently known about the potential role of aberrant DNA methylation in JIA. As a first step to addressing this knowledge gap, we have profiled DNA methylation in purified CD4+ T cells from JIA subjects and controls. Genomic DNA was isolated from peripheral blood CD4+ T cells from 14 oligoarticular and polyarticular JIA cases with active disease, and healthy age- and sex-matched controls. Genome-scale methylation analysis was carried out using the Illumina Infinium HumanMethylation27 BeadChip. Methylation data at >25,000 CpGs was compared in a case-control study design. RESULTS: Methylation levels were significantly different (FDR adjusted p<0.1) at 145 loci. Removal of four samples exposed to methotrexate had a striking impact on the outcome of the analysis, reducing the number of differentially methylated loci to 11. The methotrexate-naive analysis identified reduced methylation at the gene encoding the pro-inflammatory cytokine IL32, which was subsequently replicated using a second analysis platform and a second set of case-control pairs. CONCLUSIONS: Our data suggests that differential T cell DNA methylation may be a feature of JIA, and that reduced methylation at IL32 is associated with this disease. Further work in larger prospective and longitudinal sample collections is required to confirm these findings, assess whether the identified differences are causal or consequential of disease, and further investigate the epigenetic modifying properties of therapeutic regimens

DNA methylation at IL32 in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common autoimmune rheumatic disease of childhood. We recently showed that DNA methylation at the gene encoding the pro-inflammatory cytokine interleukin-32 (IL32) is reduced in JIA CD4+ T cells. To extend this finding, we measured IL32 methylation in CD4+ T-cells from an additional sample of JIA cases and age- and sex-matched controls, and found a reduction in methylation associated with JIA consistent with the prior data (combined case-control dataset: 25.0% vs 37.7%, p = 0.0045). Further, JIA was associated with reduced IL32 methylation in CD8+ T cells (15.2% vs 25.5%, p = 0.034), suggesting disease-associated changes to a T cell precursor. Additionally, we measured regional SNPs, along with CD4+ T cell expression of total IL32, and the γ and β isoforms. Several SNPs were associated with methylation. Two SNPs were also associated with JIA, and we found evidence of interaction such that methylation was only associated with JIA in minor allele carriers (e.g. rs10431961 p(interaction) = 0.011). Methylation at one measured CpG was inversely correlated with total IL32 expression (Spearman r = −0.73, p = 0.0009), but this was not a JIA-associated CpG. Overall, our data further confirms that reduced IL32 methylation is associated with JIA, and that SNPs play an interactive role

American College of Rheumatology Provisional Criteria for Clinically Relevant Improvement in Children and Adolescents With Childhood-Onset Systemic Lupus Erythematosus

10.1002/acr.23834ARTHRITIS CARE & RESEARCH715579-59

Aggrecanase Cleavage in Juvenile Idiopathic Arthritis Patients Is Minimally Detected in the Aggrecan Interglobular Domain but Robust at the Aggrecan C-Terminus

OBJECTIVE: To understand aggrecan degradation in juvenile idiopathic arthritis (JIA), the pattern and abundance of aggrecan fragments in synovial fluid aspirates from JIA patients were analysed and compared with aggrecan fragments in synovial fluids from patients with other arthritides, juvenile knee injury and a knee-healthy reference group. METHODS: The concentration of sulphated glycosaminoglycans in synovial fluid was measured by the Alcian blue precipitation assay. Aggrecan fragments were purified by dissociative CsCl density gradient centrifugation, deglycosylated and analysed by Western blot using antibodies specific for either aggrecanase-derived ARGS, SELE and KEEE neoepitopes, or the aggrecan G3-domain. RESULTS: The concentration of sulphated glycosaminoglycans in JIA synovial fluids was significantly lower compared with the levels in fluids from OA (P<0.001), juvenile knee injury (P=0.006) and knee-healthy reference (P=0.022) groups. Western blot analysis detected KEEE, SELE, and G3 fragments generated by aggrecanase cleavage in the chondroitin sulphate-rich region of JIA aggrecan. The pattern of JIA aggrecan fragments was not identical to that in synovial fluids pooled from OA patients, although there were notable similarities. Surprisingly, aggrecanase-derived ARGS fragments were barely detectable in the JIA synovial fluids, in marked contrast to the levels of ARGS fragments in OA synovial fluids. CONCLUSIONS: Aggrecanases appear to cleave minimally in the interglobular domain of aggrecan in JIA patients despite robust levels of cleavage in aggrecan's chondroitin-sulphate rich region. The results suggest that unlike other arthritides, aggrecanase cleavage in the aggrecan interglobular domain might not be a major pathogenic event in JIA. © 2012 American College of Rheumatology

Vaccinations Do Not Increase Arthritis Flares in Juvenile Idiopathic Arthritis: A Study of the Relationship between Routine Childhood Vaccinations on the Australian Immunisation Schedule and Arthritis Activity in Children with Juvenile Idiopathic Arthritis

Background. Juvenile idiopathic arthritis (JIA) is a collective term for a group of inflammatory conditions of uncertain origin, which causes chronic arthritis in one or more joints. The clinical course of JIA is characterised by episodes of increased activity, termed flares. Vaccinations have previously been proposed as a “trigger” for some flares, although evidence supporting this is scant. Objective. To explore whether routine childhood vaccinations are associated with an increased risk of flares of arthritis activity in children with JIA. Methods. Patients aged below 6 years with a diagnosis of JIA were recruited from the Rheumatology Clinical Database at the Royal Children’s Hospital, Melbourne, Australia, from 1 January 2010 to 30 April 2016. Patient immunisation status was cross-checked with the Australian Childhood Immunisation Register (ACIR). The self-controlled case series methodology (Rowhani-Rahbar et al., 2012) was applied to determine whether the risk of arthritis flares in the three months following immunisation was greater than the baseline risk for each patient. Results. 138 patients were included in the study. 32 arthritis flares occurred in the 90 days following immunisation. The risk of arthritis flares during the 90 days following immunisation was reduced compared with patients’ baseline risk (RR 0.59 (95% CI 0.39-0.89, p=0.012)). Conclusion. Routine childhood immunisations were not associated with arthritis flare onset in patients with JIA. The risk of arthritis flares in the 90 days following vaccination was lower than the baseline risk. In the context of COVID19, vaccination will not increase interaction with the healthcare system beyond the immunisation encounter

Independent replication analysis of genetic loci with previous evidence of association with juvenile idiopathic arthritis

BACKGROUND: Over the last five years, there have been numerous reports of association of juvenile idiopathic arthritis with single nucleotide polymorphisms (SNPs) at various loci outside the major histocompatibility complex (MHC) region. However, the majority of these association findings have been generated using a limited number of international cohorts, and thus there is benefit in further independent replication. To address this, we examined a total of 56 SNPs in 42 non-MHC gene regions previously reported to be associated with JIA, in the ChiLdhood Arthritis Risk factor Identification sTudY (CLARITY), a new Australian collection of cases and healthy child controls. FINDINGS: Genotyping was performed on a total of 324 JIA cases (mean age 9.7 years, 67.3% female) and 568 controls (mean age 7.8 years, 40.7% female). We demonstrated clear evidence for replication of association of JIA with SNPs in or around c12orf30, c3orf1, PTPN22, STAT4, and TRAF1-C5, confirming the involvement of these loci in disease risk. Further, we generated evidence supportive of replication of association of JIA with loci containing AFF3, CD226, MBL2, PSTPIP1, and RANTES (CCL5). These results were robust to sensitivity analyses for ethnicity. CONCLUSION: We have provided valuable independent data as to the underlying genetic architecture of this understudied pediatric autoimmune disease, further confirming five loci outside the MHC, and supporting a role for a further five loci in determining disease risk