Altered expression of intestinal human leucocyte antigen D-related and immune signalling molecules in juvenile idiopathic arthritis

Faecal Bacteriome and Metabolome Profiles Associated with Decreased Mucosal Inflammatory Activity Upon Anti-TNF Therapy in Paediatric Crohn's Disease

BACKGROUND AND AIMS

Treatment with anti-tumour necrosis factor α antibodies [anti-TNF] changes the dysbiotic faecal bacteriome in Crohn's disease [CD]. However, it is not known whether these changes are due to decreasing mucosal inflammatory activity or whether similar bacteriome reactions might be observed in gut-healthy subjects. Therefore, we explored changes in the faecal bacteriome and metabolome upon anti-TNF administration [and therapeutic response] in children with CD and contrasted those to anti-TNF-treated children with juvenile idiopathic arthritis [JIA].

METHODS

Faecal samples collected longitudinally before and during anti-TNF therapy were analysed with regard to the bacteriome by massively parallel sequencing of the 16S rDNA [V4 region] and the faecal metabolome by 1H nuclear magnetic resonance imaging. The response to treatment by mucosal healing was assessed by the MINI index at 3 months after the treatment started. We also tested several representative gut bacterial strains for in vitro growth inhibition by infliximab.

RESULTS

We analysed 530 stool samples from 121 children [CD 54, JIA 18, healthy 49]. Bacterial community composition changed on anti-TNF in CD: three members of the class Clostridia increased on anti-TNF, whereas the class Bacteroidia decreased. Among faecal metabolites, glucose and glycerol increased, whereas isoleucine and uracil decreased. Some of these changes differed by treatment response [mucosal healing] after anti-TNF. No significant changes in the bacteriome or metabolome were noted upon anti-TNF in JIA. Bacterial growth was not affected by infliximab in a disc diffusion test.

CONCLUSIONS

Our findings suggest that gut mucosal healing is responsible for the bacteriome and metabolome changes observed in CD, rather than any general effect of anti-TNF.

Infant gut microbiota and environment associate with juvenile idiopathic arthritis many years prior to disease onset, especially in genetically vulnerable children

BACKGROUND

The etiology of juvenile idiopathic arthritis (JIA) is poorly understood. This study investigated genetic and environmental factors and infant gut microbiota in a prospective birth cohort to assess disease risk.

METHODS

Data was collected from the All Babies in Southeast Sweden (ABIS) population-based cohort (n = 17,055), 111 of whom later acquired JIA (ABISJIA). Stool samples were collected at one year of age for 10.4%. To determine disease association, 16S rRNA gene sequences were analyzed, with and without confound adjustment. Genetic and environmental risks were assessed.

FINDINGS

ABISJIA had higher abundance of Acidaminococcales, Prevotella 9, and Veillonella parvula and lower abundance of Coprococcus, Subdoligranulum, Phascolarctobacterium, Dialister spp., Bifidobacterium breve, Fusicatenibacter saccharivorans, Roseburia intestinalis, and Akkermansia muciniphila (q's < 0.05). Parabacteroides distasonis greatly increased the odds of later contracting JIA (OR = 6.7; 1.81-24.84, p = 0.0045). Shorter breastfeeding duration and increased antibiotic exposure compounded risk in a dose-dependent manner, especially in those with genetic predisposition.

INTERPRETATION

Microbial dysregulation in infancy may trigger or accelerate JIA development. Environmental risk factors have a stronger impact on genetically predisposed children. This study is the first to implicate microbial dysregulation in JIA at such an early age, with many bacterial taxa associated with risk factors. These findings provide opportunities for intervention or early screening and offer new insights into JIA pathogenesis.

FUNDING

Barndiabetesfonden; Swedish Council for Working Life and Social Research; Swedish Research Council; Östgöta Brandstodsbolag; Medical Research Council of Southeast Sweden; JDRF-Wallenberg Foundation; Linköping.

Infections and antibiotics during fetal life and childhood and their relationship to juvenile idiopathic arthritis: a prospective cohort study

BACKGROUND

The aetiology of juvenile idiopathic arthritis (JIA) is poorly understood. It has been shown that use of antibiotics is associated with JIA. However, whether the association is due to increased occurrence of infection in these individuals is unknown. The purpose of this investigation was to measure the association between number of infections and use of antibiotics during childhood with development of JIA.

METHODS

In ABIS (All Babies in Southeast Sweden) a population-based prospective birth cohort of 17,055 children, data were collected on infections and antibiotic exposure during pregnancy and childhood. 102 individuals with JIA were identified. Multivariable logistic regression analyses were performed, adjusting for confounding factors.

RESULTS

Exposure to antibiotics during the periods 1-12 months, 1-3 years and 5-8 years was significantly associated with increased risk for JIA. The odds of developing JIA were three times higher in those exposed to antibiotics during the first 3 years of life compared with those not exposed (aOR 3.17; 95% CI 1.11-9.03, p = 0.031), and more than twice as high in those exposed to antibiotics during the first 5 years of life compared with those not exposed (aOR 2.18; 95% CI 1.36-3.50, p = 0.001). The odds of developing JIA were 78% higher in those exposed to antibiotics during the first 8 years of life compared with those not exposed (aOR 1.78; 95% CI 1.15-2.73, p = 0.009). Occurrence of infection during fetal life or childhood showed no significant association with the risk of developing JIA, after confounder adjustment. The cumulative number of courses of antibiotics was significantly higher during childhood for the individuals who developed JIA (p < 0.001). Penicillins were more frequently used than non-penicillins, but both had an equal effect on the risk of developing JIA.

CONCLUSIONS

Exposure to antibiotics early in life is associated with later onset of JIA in a large birth cohort from the general population. The relationship was dose dependent. These results suggest that further, more restrictive, antibiotic policies during the first years of life would be advisable.

Update on research and clinical translation on specific clinical areas from biology to bedside: Unpacking the mysteries of juvenile idiopathic arthritis pathogenesis

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

Cow's Milk Allergy in Infancy and Later Development of Juvenile Idiopathic Arthritis: A Register-Based Case-Control Study

We examined the association between cow's milk allergy (CMA) and juvenile idiopathic arthritis (JIA). The material for this case-control study was collected from national registers of all children born in Finland between 2000 and 2010 and diagnosed with JIA (n = 1,298) and age-, sex-, and place-matched controls (n = 5,179). We identified 235 children with CMA; 66 of these children also had JIA. A conditional logistic regression analysis was performed to evaluate the association between CMA and JIA and to test whether exposure to antibiotics would be a covariate for this association. In boys (but not in girls), a diagnosis of CMA and the use of hypoallergenic formula in infancy were associated with the later development of JIA (odds ratio = 2.4, 95% confidence interval: 1.6, 3.6). The association was most evident in boys who were diagnosed with JIA before age 3 years or diagnosed with CMA with predominantly gastrointestinal symptoms. There was no statistically significant additive interaction between CMA and antibiotic exposure in the later development of JIA. These associations may reflect impaired maturation of intestinal immunity and integrity in boys with a risk of JIA. Predisposing factors related to JIA pathogenesis seem to display a sex-linked disparity.

CD161+ Tconv and CD161+ Treg Share a Transcriptional and Functional Phenotype despite Limited Overlap in TCRβ Repertoire

Human regulatory T cells (Treg) are important in immune regulation, but can also show plasticity in specific settings. CD161 is a lectin-like receptor and its expression identifies an effector-like Treg population. Here, we determined how CD161⁺ Treg relate to CD161⁺ conventional T cells (Tconv). Transcriptional profiling identified a shared transcriptional signature between CD161⁺ Tconv and CD161⁺ Treg, which is associated with T helper (Th)1 and Th17 cells, and tissue homing, including high expression of gut-homing receptors. Upon retinoic acid (RA) exposure, CD161⁺ T cells were more enriched for CCR9⁺ and integrin α4⁺β7⁺ cells than CD161^- T cells. In addition, CD161⁺ Tconv and CD161⁺ Treg were enriched at the inflamed site in autoimmune arthritis, and both CD161⁺ and CD161^- Treg from the inflamed site were suppressive in vitro. CD161⁺ T cells from the site of autoimmune arthritis showed a diminished gut-homing phenotype and blunted response to RA suggesting prior imprinting by RA in the gut or at peripheral sites rather than during synovial inflammation. TCRβ repertoires of CD161⁺ and CD161^- Tconv and Treg from blood showed limited overlap whereas there was clear overlap between CD161⁺ and CD161^- Tconv, and CD161⁺ and CD161^- Treg from the inflamed site suggesting that the inflamed environment may alter CD161 levels, potentially contributing to disease pathogenesis.

Gut microbiota-host interactions and juvenile idiopathic arthritis

BACKGROUND

Juvenile idiopathic arthritis is the most common form of chronic arthritis in children. There is mounting evidence that the microbiota may influence the disease.

MAIN BODY

Recent observations in several systemic inflammatory diseases including JIA have indicated that abnormalities in the contents of the microbiota may be factors in disease pathogenesis, while other studies in turn have shown that environmental factors impacting the composition of the microbiota, such as delivery mode and early exposure to antibiotics, affect the risk of chronic inflammatory diseases including JIA. Microbial alterations may predispose to JIA through a variety of mechanisms, including impaired immunologic development, alterations in the balances of pro- versus anti-inflammatory bacteria, and low-grade mucosal inflammation. Additional confirmatory studies of microbiota aberrations and their risk factors are needed, as well as additional mechanistic studies linking these alterations to the disease itself.

CONCLUSIONS

The microbiota may influence the risk of JIA and other systemic inflammatory conditions through a variety of mechanisms. Additional research is required to improve our understanding of the links between the microbiota and arthritis, and the treatment implications thereof.

Histopathological features of gastrointestinal mucosal biopsies in children with juvenile idiopathic arthritis

BACKGROUND

The association between inflammatory bowel disease and joint involvement is well established. There is a paucity of data describing histopathological features of the gut in relation to juvenile idiopathic arthritis (JIA).

METHODS

We retrospectively identified 33 (21 male) children aged 3-16 y with JIA (11 with oligoarthritis, 5 with polyarthritis, 8 with systemic onset arthritis, 8 with enthesitis-related arthritis (ERA), and 1 with psoriatic arthritis) with significant gastrointestinal (GI) symptoms who underwent upper and/or lower endoscopy. The histopathological findings were reviewed in addition to presence of autoantibodies and concomitant treatment.

RESULTS

The most common GI indications for endoscopy were persistent abdominal pain (14/33 (42%)) and diarrhea (10/33 (30%)). Of the 33 children, 28 (85%) had gut mucosal inflammation, mostly affecting the colon (80%). Active inflammation of the gut was found in 5 of 28 (17%) children, and 15 of 28 (53%) children showed mild nonspecific inflammation. Eight patients (27%) had predominantly an eosinophilic infiltrate. Twenty-six patients had previously received treatment for JIA. There was a negative association with the use of immunomodulators and the presence of eosinophil inflammation.

CONCLUSION

The majority of children with JIA and GI symptoms have histological evidence of mild nonspecific inflammation, but some having active colitis and prominent eosinophil infiltrate.

Changes in fecal microbiota and metabolomics in a child with juvenile idiopathic arthritis (JIA) responding to two treatment periods with exclusive enteral nutrition (EEN)

The microbiome and immune system of the digestive tract are highly important in both health and disease. Exclusive enteral nutrition (EEN) is a common anti-inflammatory treatment in children with Crohn's disease in the European countries, and the mechanism is most likely linked to changes in the intestinal microbiome. In the present study, EEN was given in two treatment periods several months apart to a patient with very severe, disabling juvenile idiopathic arthritis (JIA), with a remarkable clinical response as the result. The aim of the present study was to study how the EEN treatment influenced the microbiome and metabolome of this patient. Fecal samples from before, during, and between treatments with EEN were studied. The microbiome was analyzed by sequencing of 16S rRNA amplicons using Illumina MiSeq, and the metabolome was analyzed using nuclear magnetic resonance. The microbiome changed markedly from treatment with EEN, with a strong reduction of the Bacteroidetes phylum. Metabolic profiles showed clear differences before, during, and between treatment with EEN, where butyrate, propionate, and acetate followed a cyclic pattern with the lowest levels at the end of each treatment period. This patient with JIA showed remarkable clinical improvement after EEN treatment, and we found corresponding changes in both the fecal microbiome and the metabolome. Further studies are needed to explore the pathophysiological role of the intestinal canal in children with JIA.

Faecal microbiome in new-onset juvenile idiopathic arthritis

Alterations in the intestinal microbial flora have been linked with autoimmune diseases. Our objective was to analyse the composition of the faecal microbiome of children with new-onset juvenile idiopathic arthritis (JIA) compared to healthy controls, and to identify specific gut bacteria associated with JIA. Stool samples from patients were taken at the time of diagnosis of JIA. The microbiome profiles of samples of 30 children with JIA (mean age 6.2 years, 22 girls) were analysed with 16S region-based sequencing profiling and compared to the stool samples of healthy controls (n = 27, mean age 5.4 years, 18 girls). The proportion of bacteria belonging to the phylum Firmicutes was significantly lower in children with JIA [21 % (95 % confident interval [CI]: 17-25 %)] compared to controls [33 % (95 % CI: 26-41 %), p = 0.009]. Bacteria belonging to Bacteroidetes were significantly more abundant in JIA [78 % (95 % CI: 74-82 %)] than in control samples [65 % (95 % CI: 57-73 %), p = 0.008]. Shared operational taxonomic units (OTUs) between the groups revealed that genera Actinobacteria and Fusobacteria were present only in JIA patients and Lentisphaerae only in controls. In summary, faecal flora in JIA is characterised by a low level of Firmicutes and an abundance of Bacteroidetes, resembling the aberration reported in type 1 diabetes. We suggest that alterations in the intestinal microbial flora may challenge the mucosal immune system of genetically susceptible subjects predisposing to local proinflammatory cascades, thus contributing to the development of JIA.

Inflammatory Bowel Disease in Juvenile Idiopathic Arthritis Patients Treated with Biologics

Objective.

Evolving inflammatory bowel disease (IBD) is a matter of interest in patients with juvenile idiopathic arthritis (JIA) and might be associated with JIA therapy.

Methods.

Data from the German biologics registry (Biologika in der Kinderrheumatologie; BiKeR) from 2001 to 2013 were analyzed.

Results.

There were 3071 patients with 8389 patient-years (PY) of observation followed. IBD was diagnosed in 11 patients, 8 with Crohn disease and 3 with ulcerative colitis. IBD incidence in patients with JIA was 1.31/1000 PY and higher than published IBD incidences in pediatric populations. Compared with the total BiKeR cohort, patients with IBD more commonly had enthesitis-related arthritis, extended oligoarthritis, psoriatic arthritis, and also rheumatoid factor (RF)-negative polyarthritis. No IBD occurred in patients with systemic JIA or RF-positive polyarthritis. In patients treated with methotrexate (MTX), the IBD incidence was significantly lower compared with patients not treated with MTX. Etanercept (ETN) monotherapy, but not the combination of ETN and MTX, was associated with an increased incidence of IBD.

Conclusion.

Incidence of IBD in patients with JIA is higher than in the population. MTX turned out to be protective, even in combination with ETN.

Repeated exposure to antibiotics in infancy: a predisposing factor for juvenile idiopathic arthritis or a sign of this group's greater susceptibility to infections?

OBJECTIVE

Previous exposure to antibiotics has been associated with the pathogenesis of several autoimmune diseases. Our objective was to explore whether childhood exposure to antibiotics would be associated with the risk of developing juvenile idiopathic arthritis (JIA).

METHODS

The material was collected from national registers containing all children born in 2000-2010 in Finland and diagnosed with JIA by the end of December 2012 (n = 1298) and appropriate controls (n = 5179) matched for age, sex, and place of birth. All purchases of antibiotics were collected from birth until the index date (i.e., the date of special reimbursement for JIA medications). A conditional logistic regression was performed to evaluate the association between the exposure to antibiotics and the risk of JIA.

RESULTS

The risk of JIA increased with the number of antibiotic purchases from birth to the index date: for ≥ 1 purchases versus none, OR 1.6, 95% CI 1.3-1.9 with an upward trend in OR (p < 0.001). Antibiotic groups lincosamides and cephalosporins showed the strongest association with JIA (OR 6.6, 95% CI 3.7-11.7, and OR 1.6, 95% CI 1.4-1.8, respectively). Overall exposure to antibiotics before 2 years of age was associated with an increased risk of JIA (OR 1.4, 95% CI 1.2-1.6), with the trend test of OR (p < 0.001).

CONCLUSION

Previous early and repeated exposure to antibiotics may predispose individuals to develop JIA. Alternatively, the apparent association may reflect shared susceptibility to infections and JIA.