OBJECTIVE: - Janus Kinase inhibitors (JAKi) are a new class of drugs available for pediatric rheumatic diseases. This study aimed to describe the safety and effectiveness of JAKi in these diseases, with a focus on longitudinal interferon-stimulated genes (ISG) assessment.
METHODS: - We present a single-center retrospective study of children with refractory pediatric rheumatic diseases including connective tissue diseases, monogenic type I interferonopathies or juvenile idiopathic arthritis, receiving JAKi. According to physicians\' assessment, treatment effectiveness was classified at 12 months as a complete response in the total absence of disease activity, partial response in case of significant (>50%) but incomplete improvement or no response in the case of non-response or improvement of less than 50% of the clinical and biological parameters. ISG were monitored longitudinally using Nanostring technology.
RESULTS: - 22 children were retrospectively included in this study, treated either by baricitinib or ruxolitinib. Complete response was achieved at 12 months in 9/22 (41%) patients. 6/22 (27%) patients were non-responders and treatment had been discontinued in five of them. Within the interferon (IFN)-related diseases group, ISG-score was significantly reduced 12 months after JAKi onset (p = 0.0068). At 12 months, daily glucocorticoid doses had been reduced with a median dose of 0.16 mg/kg/day (IQR 0.11; 0.33) (p = 0.0425). 7/22 (32%) patients had experienced side effects, infections being the most common. Increase of the body mass index was also recorded in children in the first 6 months of treatment.
CONCLUSIONS: - JAKi represent a promising treatment of immune-mediated pediatric diseases, enabling to decrease type-I IFN transcriptomic signature in responding patients, especially in the context of juvenile dermatomyositis. JAKi represent steroid-sparing drugs but they induce metabolic changes linked to weight gain, posing a concern in the treatment of young patients and teenagers. More data are required to define the efficacy and safety of JAKi in the management of refractory pediatric rheumatic diseases.

OBJECTIVE: Given the multifactorial pathogenesis of juvenile spondyloarthritis (JSpA) and evidence of a protective effect in phenotypically similar diseases, we aimed to test whether breastfeeding is associated with the development and disease activity of JSpA.
METHODS: This single-center retrospective case-control study included children with JSpA and age- and sex-matched controls with a 1:1 ratio. Univariable and multivariable conditional logistic regression modeling for matched pairs was used to test the association of infant factors with the development of JSpA, including infant nutrition and form of delivery. Linear regression was used to assess the association of JSpA disease activity (JSpA Disease Activity Index with 6 elements [JSpADA6]) at presentation with breastfeeding exposure, form of delivery, and antibiotic exposure.
RESULTS: For the 195 case-control matched pairs, the mean age was 13.0 years and 47.7% were female. For breastfeeding, 88.7% of controls and 69.2% of JSpA cases were exposed to breastfeeding of any duration, respectively (P < 0.001). In the multivariable model, exclusive breastfeeding > 6 months was independently and significantly associated with a lower chance of JSpA development (odds ratio 0.47, 95% CI 0.30-0.72; P < 0.001). The median JSpADA6 was not significantly associated with breastfeeding for > 6 months. However, vaginal delivery was significantly associated with a lower JSpADA6 (B = -0.65, 95% CI -1.13 to -0.17; P = 0.008).
CONCLUSIONS: This study suggests that infant factors that affect the microbiome may be associated with the occurrence and disease activity of JSpA at presentation.

OBJECTIVE: To evaluate immunogenicity, effectiveness and safety of COVID-19 vaccination in patients with pediatric autoimmune inflammatory rheumatic disease (pedAIIRD).
METHODS: A prospective cohort study was performed at the pediatric rheumatology department of the Wilhelmina Children\'s Hospital in Utrecht, the Netherlands. Vaccination dates, COVID-19 cases and vaccine-related adverse events (AEs) were registered for all pedAIIRD patients during regular clinic visits from March 2021 - August 2022. SARS-CoV-2 IgG antibody levels and T-cell responses were measured from serum samples after vaccination, and clinical and drug therapy data were collected from electronic medical records. Rate of COVID-19 disease was compared between vaccinated and unvaccinated patients in a time-varying Cox regression analysis.
RESULTS: A total of 157 patients were included in this study and 88 % had juvenile idiopathic arthritis (JIA). One hundred thirty-seven patients were fully vaccinated, of which 47 % used biological agents at the time of vaccination, and 20 patients were unvaccinated. Geometric mean concentrations (GMCs) of post-vaccine antibody levels against SARS-CoV-2 were above the threshold for positivity in patients who did and did not use biological agents at the time of vaccination, although biological users demonstrated significantly lower antibody levels (adjusted GMC ratio: 0.38, 95 % CI: 0.21 - 0.70). T-cell responses were adequate in all but two patients (9 %). The adjusted rate of reported COVID-19 was significantly lower for fully vaccinated patients compared to non-vaccinated patients (HR: 0.53, 95 % CI: 0.29 - 0.97). JIA disease activity scores were not significantly different after vaccination, and no serious AEs were reported.
CONCLUSIONS: COVID-19 mRNA vaccines were immunogenic (both cellular and humoral), effective and safe in a large cohort of pedAIIRD patients despite their use of immunosuppressive medication.

BACKGROUND: Pediatric rheumatic diseases (PRDs) are a group of chronic disorders that start in childhood and are characterized by periodic exacerbations and remissions of symptoms, with limitations in family, school, and social activities. The aim of this study was to detect differences in parents\' psychological adjustment and emotion regulation strategies, and parent-reported children\'s adjustments in families of children with active and inactive PRDs.
METHODS: Fifty-four parents (38 mothers and 16 fathers) of children with PRD were recruited from a pediatric unit. Disease activity was evaluated by their pediatric rheumatologist, while parents\' depressive and anxiety symptoms, emotion regulation strategies, and children\'s emotional difficulties and hyperactivity-inattention symptoms were assessed through a web-based survey.
RESULTS: Parents of children with active PRDs reported higher levels of their child\'s emotional difficulties and hyperactivity-inattention symptoms. Linear regression analysis demonstrated that having a child in the active phases of PRD and lower use of cognitive reappraisal lead to higher children\'s emotional symptoms, while active disease, low use of cognitive reappraisal, and greater expressive suppression were associated with higher hyperactivity-inattention symptoms. Our study highlights that children with PRDs and their parents may be at increased risk for psychological problems, especially during the active disease phase, highlighting the importance of a multidisciplinary approach.

BACKGROUND: Rheumatic patients have a higher frequency of tuberculosis(TB) than the general population. This study aimed to describe children and adolescents with TB and rheumatic diseases(RD) who were being treated in a reference center.
METHODS: A series of TB cases were investigated in a reference center for childhood TB in Rio de Janeiro, Brazil, from 1995 to 2022.
RESULTS: Fifteen patients with underlying RD and TB were included with 8(53%) being female. The mean age at RD diagnosis was 7.10years (SD ± 0,57 years), and the mean age at TB diagnosis was 9.81 years(SD ± 0.88 years). A total of 9 cases of pulmonary TB(PTB) and 6 cases of extrapulmonary TB-pleural(2), joint/osteoarticular(1), cutaneous(1), ocular(1), and peritoneal(1)- were described. The RD observed in the 15 patients included juvenile idiopathic arthritis(9), juvenile systemic lupus erythematosus(3), juvenile dermatomyositis(1), polyarteritis nodosa(1), and pyoderma gangrenosum(1). Among the immunosuppressants/immunobiologics, methotrexate(8) was the most commonly used, followed by corticosteroids(6), etanercept(2), mycophenolate mofetil(1), cyclosporine A(1), adalimumab(1), and tocilizumab(1). The most common symptoms were fever and weight loss, and a predominance of PTB cases was noted. GeneXpert MTB/RIF® was performed in six patients and was detectable in two without rifampicin resistance; Xpert Ultra® was performed in five patients, and traces with indeterminate rifampicin resistance were detected in three. One female patient discontinued treatment, and another passed away.
CONCLUSIONS: The case series demonstrated the importance of suspecting and investigating TB in RD affected patients who are using immunosuppressants/ immunobiologics, particularly in countries with high rates of TB such as Brazil.

UNASSIGNED: Blau syndrome (BS) and juvenile dermatomyositis (JDM) are distinct conditions with different pathophysiological mechanisms. Accurate diagnosis of BS can be challenging due to overlapping clinical features with other inflammatory conditions. This case is being reported to highlight a pediatric case initially diagnosed with JDM, and subsequently found to have BS through genetic testing.
UNASSIGNED: We present the case of a 4-year-old Arab male initially diagnosed with JDM based on skin manifestations, negative histology for another disease, and no other clinical features suggestive of an alternate diagnosis. However, subsequent symptoms suggestive of BS emerged, leading to genetic testing confirmation of BS, marking the second reported case in the region. This unique clinical scenario highlights the challenges in diagnosing BS and the potential for misinterpretation of the skin rash as JDM. Accurate differentiation between these conditions is crucial to guide appropriate management and prevent delays in treatment.
UNASSIGNED: The diagnostic process for JDM involves clinical evaluation, laboratory investigations, imaging, and biopsy findings. However, muscle biopsy may yield false-negative results. BS has been misdiagnosed as other conditions, such as Kawasaki disease and juvenile idiopathic arthritis, due to overlapping clinical features. This case highlights the significance of a thorough diagnostic strategy for BS that takes into account any potentially negative histopathology findings. A precise diagnosis is essential since misdiagnosis can result in inadequate or delayed therapy.
UNASSIGNED: The diverse presentation of the skin rash in BS can pose difficulties for physicians in distinguishing it from other pediatric rheumatological conditions, such as JDM.

OBJECTIVE: To summarize the current evidence on the adoption of the treat-to-target (T2T) strategy in pediatric rheumatic diseases (PRD).
RESULTS: The recent advances in the management of PRD have markedly increased the ability to achieve disease remission. Complete disease quiescence is regarded as the ideal therapeutic goal because its attainment leads to lesser long-term damage and physical disability, and to optimization of quality of life. Studies in adult rheumatic diseases have shown that patient outcomes are improved if complete suppression of the inflammatory process is aimed for by frequent adjustments of therapy according to quantitative indices. This approach, which underlies the T2T concept, has been applied in strategic trials in rheumatoid arthritis (RA). Furthermore, recommendations for the T2T have been issued for RA and other adult rheumatic diseases. There is currently a growing interest for the introduction of T2T in PRD, and recommendations for treating juvenile idiopathic arthritis (JIA) to target were promulgated. A similar initiative has been undertaken for childhood-onset systemic lupus erythematosus. Preliminary therapeutic studies have explored the T2T design in JIA. The T2T strategy is a modern therapeutic approach that holds the promise of improving the outcomes in patients with PRD.

Genetics play an important role in systemic lupus erythematosus (SLE) pathogenesis. We calculated the prevalence of rare variants in known monogenic lupus genes among children suspected of monogenic lupus.
We completed paired-end genome-wide sequencing (whole genome sequencing [WGS] or whole exome sequencing) in patients suspected of monogenic lupus, and focused on 36 monogenic lupus genes. We prioritized rare (minor allele frequency < 1%) exonic, nonsynonymous, and splice variants with predicted pathogenicity classified as deleterious variants (Combined Annotation Dependent Depletion [CADD], PolyPhen2, and Sorting Intolerant From Tolerant [SIFT] scores). Additional filtering restricted to predicted damaging variants by considering reported zygosity. In those with WGS (n = 69), we examined copy number variants (CNVs) > 1 kb in size. We created additive non-HLA and HLA SLE genetic risk scores (GRSs) using common SLE-risk single-nucleotide polymorphisms. We tested the relationship between SLE GRSs and the number of rare variants with multivariate logistic models, adjusted for sex, ancestry, and age of diagnosis.
The cohort included 71 patients, 80% female, with a mean age at diagnosis of 8.9 (SD 3.2) years. We identified predicted damaging variants in 9 (13%) patients who were significantly younger at diagnosis compared to those without a predicted damaging variant (6.8 [SD 2.1] years vs 9.2 [SD 3.2] years, P = 0.01). We did not identify damaging CNVs. There was no significant association between non-HLA or HLA SLE GRSs and the odds of carrying ≥ 1 rare variant in multivariate analyses.
In a cohort of patients with suspected monogenic lupus who underwent genome-wide sequencing, 13% carried rare predicted damaging variants for monogenic lupus. Additional studies are needed to validate our findings.

BACKGROUND: Transcriptome profiling of blood cells is an efficient tool to study the gene expression signatures of rheumatic diseases. This study aims to improve the early diagnosis of pediatric rheumatic diseases by investigating patients\' blood gene expression and applying machine learning on the transcriptome data to develop predictive models.
METHODS: RNA sequencing was performed on whole blood collected from children with rheumatic diseases. Random Forest classification models were developed based on the transcriptome data of 48 rheumatic patients, 46 children with viral infection, and 35 controls to classify different disease groups. The performance of these classifiers was evaluated by leave-one-out cross-validation. Analyses of differentially expressed genes (DEG), gene ontology (GO), and interferon-stimulated gene (ISG) score were also conducted.
RESULTS: Our first classifier could differentiate pediatric rheumatic patients from controls and infection cases with high area-under-the-curve (AUC) values (AUC = 0.8 ± 0.1 and 0.7 ± 0.1, respectively). Three other classifiers could distinguish chronic recurrent multifocal osteomyelitis (CRMO), juvenile idiopathic arthritis (JIA), and interferonopathies (IFN) from control and infection cases with AUC ≥ 0.8. DEG and GO analyses reveal that the pathophysiology of CRMO, IFN, and JIA involves innate immune responses including myeloid leukocyte and granulocyte activation, neutrophil activation and degranulation. IFN is specifically mediated by antibacterial and antifungal defense responses, CRMO by cellular response to cytokine, and JIA by cellular response to chemical stimulus. IFN patients particularly had the highest mean ISG score among all disease groups.
CONCLUSIONS: Our data show that blood transcriptomics combined with machine learning is a promising diagnostic tool for pediatric rheumatic diseases and may assist physicians in making data-driven and patient-specific decisions in clinical practice.

To describe the phenotype, disease course, and treatment of a large cohort of children with sarcoidosis.
Patients with biopsies consistent with sarcoidosis, performed between 2010 and 2020, were included in this study. Patients\' notes were reviewed retrospectively. Children with disease onset before 5 years of age were compared with older children. Regression analysis was performed to determine predictors of treatment outcome.
In total, 48 children with a mean age at diagnosis of 9.5 years, with a male to female ratio of 0.71, were identified. In total, 72% of the children were of Black race and 94% had multiorgan disease, with an average of 4.8 organs involved, most commonly lymph nodes (65%), skin (63%), and eyes (60%). Laboratory findings of note included raised serum calcium in 23% of patients and raised angiotensin-converting enzyme in 76% of patients. Out of 14 patients tested, 6 had mutations in NOD2. In total, 81% of patients received systemic steroids and 90% received conventional disease-modifying antirheumatic drugs (DMARDs); in 25% of patients, a biologic was added, mostly anti-tumor necrosis factor (anti-TNF). Although most patients could be weaned off steroids (58%), most remained on long-term DMARDs (85%). Children under the age of 5 years presented more often with splenomegaly (P = 0.001), spleen involvement (P = 0.003), and higher C-reactive protein (P = 0.10). Weight loss was more common in adolescents (P = 0.006). Kidney (P = 0.004), eye (P = 0.005), and liver involvement (P = 0.03) were more common in Black patients. Regression analysis identified no single factor associated with positive treatment outcomes.
Multiorgan involvement, response to steroids, and chronic course are hallmarks of pediatric sarcoidosis. The phenotype significantly varies by age and race. Where conventional DMARDs were not efficacious, the addition of an anti-TNF agent was beneficial.