Risk Factors Associated with Juvenile Idiopathic Arthritis: Exposure to Cigarette Smoke and Air Pollution from Pregnancy to Disease Diagnosis

3D chromatin-based variant-to-gene maps across 57 human cell types reveal the cellular and genetic architecture of autoimmune disease susceptibility

A portion of the genetic basis for many common autoimmune disorders has been uncovered by genome-wide association studies (GWAS), but GWAS do not reveal causal variants, effector genes, or the cell types impacted by disease-associated variation. We have generated 3D genomic datasets consisting of promoter-focused Capture-C, Hi-C, ATAC-seq, and RNA-seq and integrated these data with GWAS of 16 autoimmune traits to physically map disease-associated variants to the effector genes they likely regulate in 57 human cell types. These 3D maps of gene cis-regulatory architecture are highly powered to identify the cell types most likely impacted by disease-associated genetic variation compared to 1D genomic features, and tend to implicate different effector genes than eQTL approaches in the same cell types. Most of the variants implicated by these cis-regulatory architectures are highly trait-specific, but nearly half of the target genes connected to these variants are shared across multiple autoimmune disorders in multiple cell types, suggesting a high level of genetic diversity and complexity among autoimmune diseases that nonetheless converge at the level of target gene and cell type. Substantial effector gene sharing led to the common enrichment of similar biological networks across disease and cell types. However, trait-specific pathways representing potential areas for disease-specific intervention were identified. To test this, we pharmacologically validated squalene synthase, a cholesterol biosynthetic enzyme encoded by the FDFT1 gene implicated by our approach in MS and SLE, as a novel immunomodulatory drug target controlling inflammatory cytokine production by human T cells. These data represent a comprehensive resource for basic discovery of gene cis-regulatory mechanisms, and the analyses reported reveal mechanisms by which autoimmune-associated variants act to regulate gene expression, function, and pathology across multiple, distinct tissues and cell types.

Assessment of Cardiovascular Risk Factors in Patients with Juvenile Idiopathic Arthritis

Introduction: The aim of this study was to assess the exposure to cardiovascular disease (CVD) risk factors in patients with juvenile idiopathic arthritis (JIA). Intima–media complex thickness (IMT), selected metabolic parameters and health behaviors were assessed in the course of the study. Methods: The study included study group, which consisted of 45 patients with JIA and 37 healthy age- and sex-matched children in the control group. Analyses in both groups included anthropometric parameters, laboratory tests, IMT and a questionnaire on exposure to modifiable CVD risk factors. Results: The study confirmed that CVD risk factors were present in both groups of patients. Significantly more children with JIA had abnormal BMI (p = 0.006) compared to the control group. Children in the study group were more likely to consume fruit regularly (p = 0.021) and less likely to consume fast food (p = 0.011) and sweetened beverages (p = 0.042) than children in the control group. Only 1 patient with JIA met criteria for ideal cardiovascular health. Dietary habits were not associated with IMT values, BMI, presence of joint pain or biochemical parameters in the study group. Conclusions: Patients with JIA are exposed to cardiovascular risk factors equally to their healthy peers. Ideal cardiovascular health should be pursued in the pediatric population with particular attention paid to patients with chronic diseases (i.e., JIA). The application of carotid artery IMT measurement in the assessment of CVD risk requires studies on a larger group of patients.

Air pollution exposure and auto-inflammatory and autoimmune diseases of the musculoskeletal system: a review of epidemiologic and mechanistic evidence

Auto-inflammatory and autoimmune diseases of the musculoskeletal system can be perceived as a spectrum of rheumatic diseases, with the joints and connective tissues are eroded severely that progressively develop chronic inflammation and lesion. A wide range of risk factors represented by genetic and environmental factors have been uncovered by population-based surveys and experimental studies. Lately, the exposure to air pollution has been found to be potentially involved in the mechanisms of occurrence or development of such diseases, principally manifest in oxidative stress, local and systemic inflammation, and epigenetic modifications, as well as the mitochondrial dysfunction, which has been reported to participate in the intermediate links. The lungs might serve as a starting area of air pollutants, which would cause oxidative stress-induced bronchial-associated lymphoid tissue (iBALT) to further to influence T, B cells, and the secretion of pro-inflammatory cytokines. The binding of aromatic hydrocarbon receptor (AhR) to the corresponding contaminant ligands tends to regulate the reaction of Th17 and Tregs. Furthermore, air pollution components might spur on immune and inflammatory responses by damaging mitochondria that could interact with and exacerbate oxidative stress and pro-inflammatory cytokines. In this review, we focused on the association between air pollution and typical auto-inflammatory and autoimmune diseases of the musculoskeletal system, mainly including osteoarthritis (OA), rheumatoid arthritis (RA), spondyloarthritis (SpA) and juvenile idiopathic arthritis (JIA), and aim to collate the mechanisms involved and the potential channels. A complete summary and in-depth understanding of the autoimmune and inflammatory effects of air pollution exposure should hopefully contribute new perspectives on how to formulate better public health policies to alleviate the adverse health effects of air pollutants.

Air pollution influence on serum inflammatory interleukins: A prospective study in childhood-onset systemic lupus erythematous patients

OBJECTIVE

To assess the effect of individual exposure, in real-time, to traffic-related pollutants on serum interleukin levels of childhood-onset lupus erythematous systemic (c-SLE) patients.

METHODS

A longitudinal and observational design was conducted in 12 repeated measures of serum samples and clinical evaluations (totaling 108 measurements) of c-SLE patients over 30 consecutive months. Real-time, individual exposure to fine particles (PM_2.5) and nitrogen dioxide (NO₂) was measured with portable monitors. Generalized estimating equation was used to evaluate the association between exposure to PM_2.5 and NO₂ and the following serum cytokine levels on the 7 days preceding clinical assessment and serum collection: MCP1, IL-6, IL-8, IL-10, IL-17, IFN-alpha, and TNF-alpha. Disease activity and other risk factors were also controlled.

RESULTS

An interquartile range (IQR) increase in PM_2.5 daily concentration was significantly associated with increased levels of TNF-alpha on the third, fourth, and seventh day after exposure; IL-10 on the third and fourth day after exposure; IL-17 on the third and seventh day after exposure; and INF-alpha on the third day after exposure (p < 0.05). An IQR increase in 7-day moving average of PM_2.5 was associated with a 6.2 pg/mL (95% CI: 0.5; 11.8; p = 0.04) increase in serum IFN-alpha level. An unexpected significant association was observed between an IQR increase in NO₂7-day cumulative concentration and a decrease of 1.6 pg/mL (95% CI: -2.6; -0.7; p < 0.001) in serum IL-17.

CONCLUSION

Real-time exposure to PM_2.5 prospectively associated with increased serum TNF-alpha, INF-alpha, IL-10, and IL-17 levels in c-SLE patients.

Role of Environment in Pediatric Rheumatic Diseases

Studying environmental risk factors for pediatric rheumatic diseases (PRD) is important because the identification of these factors may lead to strategies to prevent disease, and to new insights into pathogenesis and therapeutic targets. Compared with other chronic diseases, there are few environmental epidemiology studies in PRD. Although strong risk factors common to all PRDs have not been identified, some exposures including infection, smoke exposure, and ultraviolet radiation have been associated with several of them. High-technology studies, especially of microbiomics and metabolomics, are increasing and will likely lead to new understandings of the complex interplay between environment, genetics, and disease.

Cardiovascular Health in Pediatric Rheumatologic Diseases

Cardiovascular disease risk is evident during childhood for patients with juvenile systemic lupus erythematosus, juvenile dermatomyositis, and juvenile idiopathic arthritis. The American Heart Association defines cardiovascular health as a positive health construct reflecting the sum of protective factors against cardiovascular disease. Disease-related factors such as chronic inflammation and endothelial dysfunction increase cardiovascular disease risk directly and through bidirectional relationships with poor cardiovascular health factors. Pharmacologic and nonpharmacologic interventions to improve cardiovascular health and long-term cardiovascular outcomes in children with rheumatic disease are needed.

Moving from nature to nurture: a systematic review and meta-analysis of environmental factors associated with juvenile idiopathic arthritis

Objectives

JIA is the most common paediatric rheumatic disease, thought to be influenced by both genetics and the environment. Identifying environmental factors associated with disease risk will improve knowledge of disease mechanism and ultimately benefit patients. This review aimed to collate and synthesize the current evidence of environmental factors associated with JIA.

Methods

Four databases (MEDLINE, Embase, Web of Science and Cumulative Index to Nursing and Allied Health Literature) were searched from inception to January 2020. Study quality was rated using the Newcastle-Ottawa Scale. Pooled estimates for each environmental factor were generated using a random-effects, inverse-variance method, where possible. The remaining environmental factors were synthesized in narrative form.

Results

This review includes 66 environmental factors from 39 studies (11 cohort and 28 case-control studies) over 45 years. Study sample sizes ranged from 41 to 1.9 million participants. Eight environmental factors from ten studies were meta-analysed. Caesarean section delivery was associated with increased JIA risk [pooled odds ratio (OR) 1.11, 95% CI: 1.01, 1.22]. Conversely, presence (vs absence) of siblings (pooled OR 0.60, 95% CI: 0.44, 0.81) and maternal prenatal smoking (pooled OR 0.70, 95% CI: 0.58, 0.84) were associated with decreased JIA risk.

Conclusion

This review identifies several environmental factors associated with JIA and demonstrates the huge breadth of environmental research undertaken over five decades. We also highlight the challenges of combining data collected over this period due to limited between study comparability, evolution in healthcare and social practices, and changing environment, which warrant consideration when planning future studies.

Adverse Childhood Experiences Are Associated with Childhood-Onset Arthritis in a National Sample of US Youth: An Analysis of the 2016 National Survey of Children's Health

OBJECTIVES

To determine whether there is an association between adverse childhood experiences (ACEs) and childhood-onset arthritis, comparing youth with arthritis to both healthy youth and youth with other acquired chronic physical diseases (OCPD); and to examine whether ACEs are associated with disease-related characteristics among children with arthritis.

STUDY DESIGN

In a cross-sectional analysis of data from the 2016 National Survey of Children's Health we examined whether ACEs were associated with having arthritis vs either being healthy or having a nonrheumatologic OCPD. ACE scores were categorized as 0, 1, 2-3, ≥4 ACEs. Multinomial logistic regression models examined associations between ACEs and health status while adjusting for age, sex, race/ethnicity, and poverty status. Among children with arthritis, associations between ACEs and disease-related characteristics were assessed by Pearson χ² analyses.

RESULTS

Compared with children with no ACEs, children with 1, 2-3, and ≥4 ACEs had an increased odds of having arthritis vs being healthy (adjusted OR for ≥4 ACEs, 9.4; 95% CI, 4.0-22.1) and vs OCPD (adjusted OR for ≥4 ACEs, 3.7; 95% CI-1.7, 8.1). Among children with arthritis, ACEs were associated with worse physical impairment.

CONCLUSIONS

Children with higher numbers of ACEs are more likely to have arthritis, when arthritis status is compared either with being healthy or with having OCPD. Further studies are needed to determine the direction of the association between ACEs and childhood arthritis, its impact on disease course, and potential intervention targets that might mitigate these effects.

Exposure to fine particulate matter (PM2.5) and pediatric rheumatic diseases

Few studies have assessed the association between fine particulate matter (PM_2.5) exposure during pregnancy and infancy and pediatric rheumatic diseases (PRDs). The goal of this study was to investigate the association of PM_2.5 with PRDs, and to explore sensitive windows of exposure. Therefore, we conducted a cohort-based case-control study to investigate the association between weekly exposure to PM_2.5 and PRDs in Taiwan. Our birth cohort consisted of infants born in 2004-2014 (n = 1,991,592) who were followed from conception to the end of 2015. There were 2363 cases of incident PRDs in children, and 23,630 children served as controls using density matching (1:10) based on date of birth, gender, and gestational week. We used a linear mixed effect (LME) model to incorporate the aerosol optical depth (AOD), meteorological variables, and land-use data to predict daily PM_2.5 concentrations. We also performed conditional logistic regression with distributed lag non-linear models (DLNMs) to assess the effects of weekly average PM_2.5 on PRDs, as well as dose-response relationships. In DLNMs, exposure to PM_2.5 during pregnancy (11-40 weeks) or infancy (1-14 weeks after birth) was associated with incident PRDs adjusting for potential confounding factors, and for carbon monoxide and sulfur dioxide. In the dose-response association, the odds ratios of PRDs were significantly increased for PM_2.5 exposures between 26 and 54 μg/m³. In addition, exposure to PM_2.5 above 81 μg/m³ dramatically increased the risk of PRDs. In conclusions, our study provides new data to suggest that PM_2.5 exposure from 11-40 gestational weeks to 1-14 weeks after birth can increase the risk for PRDs in a non-linear dose-response fashion.

Gut microbiota in children with juvenile idiopathic arthritis: characteristics, biomarker identification, and usefulness in clinical prediction

Background

Recent studies have suggested that the gut microbiota is altered in children with juvenile idiopathic arthritis (JIA). However, age, sex, and body mass index (BMI) were not matched in the previous studies, and the results are inconsistent. We conducted an age-, sex-, and BMI-matched cross-sectional study to characterize the gut microbiota in children with JIA, and evaluate its potential in clinical prediction.

Methods

A total of 40 patients with JIA and 42 healthy controls, ranging from 1 to 16 years, were enrolled in this study. Fecal samples were collected for 16S rDNA sequencing. The data were analyzed using QIIME software and R packages. Specifically, the random forest model was used to identify biomarkers, and the receiver operating characteristic curve and the decision curve analysis were used to evaluate model performance.

Results

A total of 39 fecal samples from patients with JIA, and 42 fecal samples from healthy controls were sequenced successfully. The Chao 1 and Shannon–Wiener index in the JIA group were significantly lower than those in the control group, and the Bray-Curtis dissimilarity also differed significantly between the two groups. The relative abundance of 4 genera, Anaerostipes, Dialister, Lachnospira, and Roseburia, decreased significantly in the JIA group compared to those in the control group. The 4 genera included microbes that produce short-chain fatty acids (SCFAs) and were negatively correlated with some rheumatic indices. Moreover, 12 genera were identified as potential biomarkers by using the nested cross-validation function of the random forest. A random forest model constructed using these genera was able to differentiate the patients with JIA from the healthy controls, and the area under the receiver operating characteristic curve was 0.7975. The decision curve analysis indicated that the model had usefulness in clinical practice.

Conclusions

The gut microbiota in patients with JIA is altered and characterized by a decreased abundance of 4 SCFA-producing genera. The decreases in the 4 genera correlated with more serious clinical indices. Twelve genera could be used as biomarkers and predictors in clinical practice.

Trial registration

The study is registered online at the Chinese Clinical Trial Registry on 11 May 2018 (registration number: ChiCTR1800016110).

Review of environmental factors and juvenile idiopathic arthritis

Juvenile idiopathic arthritis is a common rheumatic disease that presents as chronic childhood arthritis. JIA is considered a multifactorial disease that may result from diverse genetic and environmental risk factors. A minority of the population-attributable risk of JIA is estimated to be due to familial factors. Thus, non-genetic or environmental factors likely account for a majority of the risk of developing JIA. Yet, while substantial data have linked environmental factors to the development of rheumatoid arthritis, similar evidence regarding JIA is sparse. This narrative review provides updates on recent literature about environmental factors that might influence the risk of developing JIA, including studies about potentially beneficial and harmful influences as well as factors with unclear effects.

Risk of juvenile idiopathic arthritis among children conceived after fertility treatment: a nationwide registry-based cohort study

STUDY QUESTION

Is the risk of juvenile idiopathic arthritis (JIA) increased in children conceived after fertility treatment, and is an observed association caused by specific types of fertility treatment or by factors associated with the underlying infertility?

SUMMARY ANSWER

The risk of JIA in children conceived after fertility treatment (any and specific types of fertility treatment) was not convincingly affected when compared with children born to fertile women.

WHAT IS KNOWN ALREADY

It has been suggested that fertility treatment may affect the development of the immune system and thereby increase the risk of developing autoimmune diseases, including JIA.

STUDY DESIGN, SIZE, DURATION

This retrospective population-based cohort study included all live-born children in Denmark between 1 January 1996 and 31 December 2012 (n = 1 084 184). The study population was followed from date of birth until first diagnosis of JIA as registered in the Danish National Patient Registry, date of 16th birthday, date of emigration, date of death or end of follow-up (31 December 2014), whichever occurred first.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study cohort was linked to the Danish Infertility Cohort in order to identify children born to women with fertility problems (n = 174 702) and fertility treatment (n = 89 931). Cox proportional hazard regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for potential confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

During a median follow-up period of 10.3 years, 2237 children were diagnosed with JIA. Children born to women with fertility problems had an increased risk of JIA (HR 1.18, 95% CI 1.05-1.32) compared with children born to fertile women. However, the risk was not increased in children conceived after any fertility treatment (HR 1.11; 95% CI 0.95-1.29), or after specific types of fertility treatment being ART (HR 1.05; 95% CI 0.83-1.33), IVF (HR 1.01; 95% CI 0.73-1.38), ICSI (HR 0.98; 95% CI 0.64-1.50) or any fertility drugs (HR 1.10; 95% CI 0.94-1.28) compared with children born to fertile women. The associations between fertility treatment and JIA were also assessed by using children born to women with fertility problems without fertility treatment in the index pregnancy as a reference group, however, the findings did not change substantially.

LIMITATIONS REASONS FOR CAUTION

Despite a large study population, the statistical precision in some subgroup analyses may be affected due to the low number of JIA cases. There may be some misclassification of fertility problems, as some women have undiagnosed fertility problems and are therefore not included in the Danish Infertility Cohort; potentially leading to slight attenuation of the association between fertility problems and JIA.

WIDER IMPLICATIONS OF THE FINDINGS

The results are based on national data and our findings can therefore be applied to other similar populations. Our results indicate that fertility treatment per se do not increase the risk of JIA but merely that the increased risk of JIA observed among children born to women with fertility problems may be due to underlying factors related to both infertility and JIA. However, as this is the first large study in this field, further studies are needed to confirm our findings.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by grants from the Jascha Foundation, the Aase and Ejner Danielsens Foundation and The Danish Rheumatism Association. All authors report no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Evaluation of disease activity in a low-income juvenile idiopathic arthritis cohort

Determine disease activity in a low income juvenile idiopathic arthritis (JIA) cohort. 164 JIA patients from families with less than US$ 4500.00/capita mean annual income followed in Fortaleza-CE, Brazil, were cross-sectionally evaluated between May 2015-April 2016. Mean age was 14 ± 5.1 years (95 female) with 10.31 ± 3.7 years disease duration. Polyarticular category predominated, with 63 (38.4%) patients, followed by 40 (24%) enthesitis-related (ERA), and 36 (22%) oligoarticular. All but 1 out of 84 parents declared less than US$ 10,000.00 annual family income. Eighty-eight (60.7%) were receiving methotrexate and 19 (13%) leflunomide including 12 (63%) using both; 46 (28%) were on biologic DMARD including 20 (43.5%) adalimumab, 17 (41.5) etanercept, 5 (10.8%) tocilizumab, 2 (4.2%) abatacept, and 1 (2.1%) each on infliximab and canakinumab. Mean CHAQ and JADAS27 were 0.36 ± 0.55 and 5.31 ± 8.5, respectively. Thirty-two (20%) out of 159 patients had deformities. A bivariate analysis revealed that polyarticular had more deformities than oligoarticular patients (p = 0.002; OR = 2.389; 95% CI 1.37-4.14). Logistic regression showed no association between high JADAS and family income (p = 0.339; OR = 1.45; 95% CI 0.67-3.31). A general linear model showed significantly lower CHAQ score in patients from families earning more as compared to those earning less than 300.00 US$ monthly (p = 0.002). This study reports JIA disease activity in a low income population. Low income apparently did not influence prognosis given the low mean JADAS27 and CHAQ scores vis-à-vis data from other cohorts.