Limitations in the classification of childhood-onset rheumatoid arthritis

Rheumatoid factor value for determining the first biologic agent to use for non-systemic juvenile idiopathic arthritis

OBJECTIVES

Currently, no indicators on which biologic disease-modifying anti-rheumatic drugs (bDMARDs) should be used first for juvenile idiopathic arthritis (JIA) have been established. Thus, this study aimed to determine the useful biomarkers in JIA to enable the best selection of the first bDMARDs without primary failure.

METHODS

This retrospective study used data of patients examined for JIA between 2015 and 2021 at Kagoshima University Hospital in Japan.

RESULTS

Altogether, 67 cases of non-systemic JIA were analyzed, excluding cases that had been treated for <6 months. Of the 67 cases, 52 were treated with bDMARDs and all rheumatoid factor (RF)+ types (32 cases) were treated with bDMARDs. Eleven cases (31.4&) (all were RF+ types and used anti-tumor necrosis factor (TNF)α agents) switched to other bDMARDs because of primary failure, and nine cases had secondary failure (6;anti-TNF, 3;anti-Interleukin-6). A significant difference in pre-treatment RF values (177.9 vs 25.7 IU/ml, p = 0.002) and presence (Odds Ratio 1.952,p = 0.004) were observed between the primary failure group and effective group.

CONCLUSIONS

RF+ JIA required bDMARDs with high probability. JIA with high titre of RF tends to be refractory to anti-TNFα agents. Tocilizumab or abatacept could be a first-choice bDMARD in such cases.

Immunometabolic Analysis of Synovial Fluid from Juvenile Idiopathic Arthritis Patients

Juvenile idiopathic arthritis (JIA) is an inflammatory rheumatic disorder. Polymorphonuclear neutrophils (PMNs) are present in JIA synovial fluid (SF), but with variable frequency. SF PMNs in JIA were previously shown to display high exocytic but low phagocytic and immunoregulatory activities. To further assess whether the degree of SF neutrophilia associated with altered immune responses in JIA, we collected SF and blood from 16 adolescent JIA patients. SF and blood leukocytes were analyzed by flow cytometry. SF and plasma were used for immune mediator quantification and metabolomics. Healthy donor blood T cells were cultured in SF to evaluate its immunoregulatory activities. PMN and T cell frequencies were bimodal in JIA SF, delineating PMN high/T cell low (PMNHigh) and PMN low/T cell high (PMNLow) samples. Proinflammatory mediators were increased in SF compared with plasma across patients, and pro- and anti-inflammatory mediators were further elevated in PMNHigh SF. Compared to blood, SF PMNs showed increased exocytosis and programmed death-1/programmed death ligand-1 expression, and SF PMNs and monocytes/macrophages had increased surface-bound arginase-1. SPADE analysis revealed SF monocyte/macrophage subpopulations coexpressing programmed death-1 and programmed death ligand-1, with higher expression in PMNHigh SF. Healthy donor T cells showed reduced coreceptor expression when stimulated in PMNHigh versus PMNLow SF. However, amino acid metabolites related to the arginase-1 and IDO-1 pathways did not differ between the two groups. Hence, PMN predominance in the SF of a subset of JIA patients is associated with elevated immune mediator concentration and may alter SF monocyte/macrophage phenotype and T cell activation, without altering immunoregulatory amino acids.

Decreased PD-1 expression on circulating CD4+T cell and PD-L1 expression on myeloid dendritic cell correlate with clinical manifestations in systemic juvenile idiopathic arthritis

OBJECTIVES

Programmed cell death-1 (PD-1) and its ligand (PD-L1) mediate negative signal in autoimmune diseases. While little is known about its role in juvenile idiopathic arthritis (JIA). The study aimed to reveal the circulating cell profile and the relative PD-1/PD-L1 expression of JIA subsets, elucidating their underlying immunomodulatory mechanisms.

METHODS

We detected the circulating cells and the relative PD-1/PD-L1 signaling in 101 JIA patients and 50 controls by flow cytometry and analyzed their association with disease activity and clinical manifestations.

RESULTS

Different from other JIA types, active systemic JIA (sJIA) patients had lower percentage and count of CD4⁺T cells and lower PD-1 expression on them compared with healthy controls (P<0.05), active polyarthritis (P<0.05) and enthesitis-related arthritis (ERA) patients (P<0.05). Also, they had higher percentage and count of myeloid dendritic cell (mDC) and lower PD-L1 expression on mDC compared with healthy controls (P<0.05). Both PD-1 on CD4⁺T cell and PD-L1 on mDC were negatively correlated with JADAS-27 in sJIA patients (P<0.05). In addition, PD-1 expression on CD4⁺T cell was negatively associated with the number of involved joints (P<0.05) and PD-L1 on mDC was lower in patients with fever (P<0.01), which could further divide patients into two groups of different manifestations.

CONCLUSIONS

Our finding displayed decreased CD4⁺T cell, increased mDC and reduced PD-1/PD-L1 signal in sJIA PBMC comparing with other JIA subsets, which might be helpful in JIA differential diagnosis and responsible for distinct clinical manifestations via different mechanisms.

Joint Fluid, Bone Marrow Edemalike Changes, and Ganglion Cysts in the Pediatric Wrist: Features That May Mimic Pathologic Abnormalities-Follow-Up of a Healthy Cohort

OBJECTIVE

The presence of findings at wrist MRI that may mimic disease is a diagnostic problem. The purpose of this study is to examine the occurrence of bone marrow changes resembling edema, joint fluid, and ganglion cysts over time, in a cohort of healthy children.

MATERIALS AND METHODS

Seventy-four of 89 healthy children included in a study of normal MRI findings of the wrists were reexamined after a period of 4 years, using the same 1.5-T MRI technique-namely, a coronal T1-weighted and a T2-weighted fat-saturated sequence. A history of handedness, diseases, and sports activity was noted.

RESULTS

Bone marrow edema or edemalike changes were seen in 29 of 74 (39.2%) wrists in 2013 as compared with 35 of 72 (48.6%) wrists in 2009 (p = 0.153), all in different locations. Changes were found in central parts of the bone, on both sides of a joint, or near bony depressions. Fifty percent of all subjects had at least one fluid pocket greater than or equal to 2 mm. The location was unchanged in 47% of the joints. In 24% of the individuals, at least one ganglion cyst was seen. Six ganglion cysts present on the first scan were not seen on the follow-up scan, and 11 new ganglion cysts had appeared.

CONCLUSION

Awareness of normal MRI appearances of the growing skeleton is crucial when interpreting MRI of children, and such findings must not be interpreted as pathologic abnormalities.

Remission rate is not dependent on the presence of antinuclear antibodies in juvenile idiopathic arthritis

Recently, it has been hypothesized that the subcategories of the ILAR classification of juvenile idiopathic arthritis (JIA) are not homogeneous, and that the presence of antinuclear antibodies (ANA) should lead to a separate entity. Therefore, the aim of this study was to evaluate ANA positivity as a predictor of achieving remission. A retrospective single-center cohort study including all JIA patients diagnosed between January 2000 and May 2014. A minimum follow-up of 1 year was required plus the ANA status. ANA positivity was defined as at least two positive results with a titer ≥1:160. Demographic and clinical features were collected. Remission at last follow-up was defined by the Wallace criteria. A total of 625 patients met the inclusion criteria and 230 (37%) were found ANA positive. Analysis showed no difference in remission rate between ANA-positive and ANA-negative patients. Additionally, joint count at diagnosis and at last follow-up were comparable in both groups. ANA positivity was correlated to a female predominance and young age at diagnosis (p < 0.001). Remission rates are not different in ANA-positive patients than in ANA-negative patients. This does not support the hypothesis to possibly divide JIA patients based on their ANA status.

Symptoms of periodontitis and antibody responses to Porphyromonas gingivalis in juvenile idiopathic arthritis

BACKGROUND

The association between rheumatoid arthritis (RA) and periodontitis is well established. Some children with juvenile idiopathic arthritis (JIA) phenotypically resemble adults with RA, characterized by the presence of anti-cyclic citrullinated peptide (CCP) antibodies. We sought to investigate an association between CCP-positive JIA and symptoms of periodontitis and antibodies to oral microbiota.

METHODS

Antibodies to oral pathogens Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum were measured using ELISA in 71 children with CCP-positive JIA and 74 children with CCP-negative JIA. Oral health history was collected from 37 children with CCP-positive JIA and 121 children with CCP-negative JIA. T-tests, Chi-square tests, Mann-Whitney U tests, and multivariable regression were used to compare the groups.

RESULTS

Compared to those with CCP-negative JIA, children with CCP-positive JIA were more likely to be female, older and non-Caucasian. Anti-P. gingivalis (p <0.003) and anti-P. intermedia (p <0.008) IgG antibody titers were higher in the CCP-positive cohort. Differences in P. gingivalis antibody titers remained significant after adjusting for age (p = 0.007). Children with CCP-positive JIA more likely reported tender/bleeding gums (43 % vs. 24 %, p < 0.02) compared to children with CCP-negative JIA. After controlling for age at collection, the odds of having tender/bleeding gums were 2.2 times higher in the CCP-positive group compared (95 % CI 0.98 - 4.83; p = 0.056).

CONCLUSIONS

Children with CCP-positive JIA have higher antibody titers to P. gingivalis and more symptoms of poor oral health, supporting a possible role for periodontitis in the etiology of CCP-positive JIA.

Immunogenetics of juvenile idiopathic arthritis: A comprehensive review

Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory arthropathy of childhood. Juvenile idiopathic arthritis is believed to be a complex genetic trait influenced by both genetic and environmental factors. Twin and family studies suggest a substantial role for genetic factors in the predisposition to JIA. Describing the genetics is complicated by the heterogeneity of JIA; the International League of Associations for Rheumatology (ILAR) has defined seven categories of JIA based on distinct clinical and laboratory features. Utilizing a variety of techniques including candidate gene studies, the use of genotyping arrays such as Immunochip, and genome wide association studies (GWAS), both human leukocyte antigen (HLA) and non-HLA susceptibility loci associated with JIA have been described. Several of these polymorphisms (e.g. HLA class II, PTPN22, STAT4) are shared with other common autoimmune conditions; other novel polymorphisms that have been identified may be unique to JIA. Associations with oligoarticular and RF-negative polyarticular JIA are the best characterized. A strong association between HLA DRB1:11:03/04 and DRB1:08:01, and a protective effect of DRB1:15:01 have been described. HLA DPB1:02:01 has also been associated with oligoarticular and RF-negative polyarticular JIA. Besides PTPN22, STAT4 and PTPN2 variants, IL2, IL2RA, IL2RB, as well as IL6 and IL6R loci also harbor variants associated with oligoarticular and RF-negative polyarticular JIA. RF-positive polyarticular JIA is associated with many of the shared epitope encoding HLA DRB1 alleles, as well as PTPN22, STAT4 and TNFAIP3 variants. ERA is associated with HLA B27. Most other associations between JIA categories and HLA or non-HLA variants need confirmation. The formation of International Consortia to ascertain and analyze large cohorts of JIA categories, validation of reported findings in independent cohorts, and functional studies will enhance our understanding of the genetic underpinnings of JIA.

Effect of methotrexate on the mandibular development of arthritic rabbits

INTRODUCTION

Juvenile idiopathic arthritis affecting the temporomandibular joint (TMJ) can cause severe disturbances of the mandibular development. Methotrexate (MTX) is often administered as a common used remission-inducing agent to treat this disease. The aim of this study was to investigate the effect of low dose MTX on the mandibular growth in arthritic rabbits.

SUBJECTS AND METHODS

Eighteen 10-week-old female New Zealand white rabbits were randomly assigned to three groups with six animals in each group. After being sensitized to ovalbumin (OA), the first and the second group received intra-articular injections with OA. The first group remained untreated, the second was treated by weekly injections of MTX. Cephalograms were taken from each animal at 10, 13, 16, 19, and 22 weeks of age and six mandibular distances measured.

RESULTS

All distances showed an increase between 10 and 20 per cent, whereas growth was more accentuated in the sagittal dimension. Significant differences in the overall growth could be observed between the arthritic and the control animals and less accentuated between the arthritic and the MTX animals. In contrast, existing differences between the groups were not significant during the intervals, but time had the greatest influence on mandibular growth.

CONCLUSIONS

MTX seems to have a positive impact on growth in rabbits suffering from experimental arthritis of the TMJ.

Effect of methotrexate upon antigen-induced arthritis of the rabbit temporomandibular joint

BACKGROUND

Juvenile idiopathic arthritis (JIA) of the temporomandibular joint (TMJ) can cause severe growth disturbances of the craniomandibular system. Antigen-induced arthritis (AIA) of the rabbit TMJ is simulating the inflammatory process of the TMJ in JIA. The aim of this study was to investigate the effect of a systemic administration of methotrexate (MTX) on AIA in rabbits by means of three different histological staining methods.

METHODS

After sensitization, a bilateral arthritis of the TMJ was induced by an intra-articular administration of ovalbumin in 12 New Zealand white rabbits aged 10 weeks. From the 13th week of age, six of the 12 rabbits received weekly intramuscular injections of MTX, and the other six animals remained without therapy. Another six animals served as controls, receiving no treatment or intra-articular injections at all. After euthanasia at the age of 22 weeks, all TMJs were retrieved en bloc. Sagittal sections were cut and stained with haematoxylin-eosin (H-E), Safranin-O for the evaluation of the Mankin score and tartrate-resistant acid phosphatase (TRAP).

RESULTS

In the arthritis group, a chronic inflammation with degeneration of the articular cartilage was visible. In the MTX group, the signs of cartilage degeneration were significantly reduced compared with the arthritis group. In contrast, the joints in the control group were inconspicuous. A correlation between the Mankin score and TRAP-positive cells could be found.

CONCLUSIONS

Systemic administration of MTX seems to have a positive effect upon the inflammatory process in the rabbit TMJ but fails to eliminate the sign of arthritis completely.