Ausra Snipaitiene

Biomarker search for juvenile idiopathic arthritis (JIA) diagnosis and monitoring remain the focus of research worldwide. Several microRNAs (miRNAs) have been identified as relevant in different rheumatic conditions; however, studies in JIA remain limited. Our study aimed to explore the potential of serum and urine-derived miRNAs for JIA diagnostics and longitudinal JIA monitoring. In this single-center, prospective study, three selected miRNAs (miR-16, -146a and -155) were tested in serial serum and urine samples collected from 31 JIA patients and 22 healthy controls (HC) via quantitative reverse transcription polymerase chain reaction (RT‒qPCR). The diagnostic performance of variables for distinguishing JIA patients from HCs was assessed by determining the area under the receiver operating characteristic (ROC) curve (AUC). The prediction of remission was evaluated using Cox regression and Kaplan-Meier analyses. A p-value < 0.05 was considered statistically significant. Lower miR-16 and higher miR-155 levels were detected in serum of JIA patients’ vs. HC (p < 0.01), whereas the level of miR-146a was lower in urine of JIA patients (p = 0.032). In ROC analysis, miR-16 and miR-155 distinguished JIA patients from HC when analyzed in serum (AUC 0.81, 95% CI 0.70–0.93, p < 0.001 and AUC 0.73, 95% CI 0.59–0.87, p = 0.005, respectively), and miR-146a– in urine (AUC 0.68, 95% CI 0.53–0.82, p = 0.030). During 12 months follow-up period increasing miR-16 (p = 0.021) and decreasing miR-155 (p = 0.009) levels were observed in serum samples. Kaplan-Meier survival analysis revealed that a high level of miR-146a in serum significantly predicts JIA remission (HR = 2.2, 95% CI 0.7–6.9, p = 0.040). This study highlights the utility of miRNAs in JIA diagnosis, monitoring and prognosis and demonstrates the feasibility of using urine as a noninvasive source of miRNAs in children with non-systemic JIA.

Introduction: Juvenile idiopathic arthritis (JIA) is a group of rare musculoskeletal disorders with chronic inflammation of joints, typically manifesting before the age of 16 years. The assessment of disease activity remains pivotal in JIA treatment decisions, particularly during clinical remission. While musculoskeletal ultrasound (MSUS) has shown promise in detecting subclinical synovitis, longitudinal data on MSUS features in JIA remains limited. The aim of this study was to evaluate the prevalence of subclinical synovitis observed in MSUS over a follow-up period in JIA patients. Additionally, it sought to assess the consistency and correlation between clinical findings, standardized composite clinical score (JADAS10), and MSUS-detected synovitis during 9 months follow-up.Patients and methods: a prospective single-center study was conducted, enrolling all consecutive JIA patients (excluding systemic JIA) seen at the study center in one year period. At three-months intervals over a 9 months period (M0, M3, M6 and M9), patients underwent clinical examination, laboratory tests, and MSUS assessment. Data on demographic characteristics, disease profile, and treatment were collected. Patients were categorized into active disease (ACT) or remission (REM) groups based on Wallace criteria and JADAS10 scores using previously validated thresholds. The ultrasound assessments adhered to the Outcome Measures in Rheumatology Clinical Trials (OMERACT) pediatric group, covering 40 joints, were performed by two ultrasonographers at every visit. Subclinical synovitis was defined as synovitis detected exclusively by MSUS. Spearman's correlation coefficients (r_s) were used to evaluate the association between MSUS, clinical data, and outcome measures, such as active joint count (ACJ), patient's/parent's global assessment of disease activity (PaGA), physician's global assessment of disease activity (PhGA) and JADAS10.Results: subclinical synovitis was evident in 5.2% of all joints and in 80.6% of the patients at baseline. During the follow-up period, signs of subclinical synovitis decreased to 3.8% of joints, however, the proportion of affected patients remained high (67.7%), with the majority in REM group. Despite the consistent strong correlation between PaGA and PhGA throughout the study (r_s> 0.895; p < 0.001), both measures displayed moderate (r_s= 0.647; p < 0.001) to weak (r_s= 0.377; p = 0.04) correlations with MSUS findings. Notably, PaGA remained significantly correlated with MSUS at the M9 visit (r_s= 0.377, p = 0.04), while PhGA showed no correlation (p = 0.094).Conclusions: The study results indicate the persistence of subclinical inflammation detected by MSUS in a significant proportion of JIA patients, even during clinical remission. Moreover, the findings suggest that conventional measurements of JIA activity may be insufficient for assessing patients in clinical remission.

Polymyositis is a rarely reported complication of COVID-19 illness, especially in children. Molecular mimicry may be a cause of hyperactivated autoimmunity, leading to various clinical manifestations, including myopathies. Symptoms vary from mild muscle weakness to severe rhabdomyolysis. We review the literature on post-COVID myositis and report a case of severe polymyositis in a 7-year-old boy, following undefined viral infection 3 weeks before the onset of muscle pain. Patient’s condition deteriorated from physical activity-associated pain in the lower limbs to severe muscle weakness leading to dysphagia and mechanical ventilation. As antibodies against SARS-CoV-2 were detected and other possible conditions causing myositis were excluded, the diagnosis of post-COVID polymyositis was considered as the most likely. The patient was treated with high doses of methylprednisolone and cyclophosphamide, resulting in improvement. Although COVID-19 is becoming a seasonal disease, the infection itself and post-viral disorders, such as polymyositis, are still of great interest and require better investigation to ensure appropriate management for each individual. Our experience suggests that aggressive immunosuppressive therapy might be a solution for severe post-COVID-related diseases. This literature review is provided in addition to the case report presented at the 29th European Paediatric Rheumatology Congress; the abstract is available online in the Proceedings of the 29th European Paediatric Rheumatology Congress.

Introduction: Multisystem inflammatory syndrome in children (MIS-C) has been reported as one of the cytokine storm syndromes associated with COVID-19. Despite the several proposed diagnostic criteria, MIS-C remains a diagnostic and clinical challenge. Recent studies have demonstrated that platelets (PLTs) play a crucial role in COVID-19 infection and its prognosis. This study aimed to investigate the clinical importance of PLT count and PLT indices in predicting MIS-C severity in children.Patients and methods: We conducted a retrospective single-center study at our university hospital. A total of 43 patients diagnosed with MIS-C during a 2-year period (from October 2020 to October 2022) were included in the study. MIS-C severity was evaluated according to the composite severity score.Results: Half of the patients were treated in the pediatric intensive care unit. No single clinical sign was associated with a severe condition, except for shock (p = 0.041). All the routine biomarkers, such as complete blood count (CBC) and C-reactive protein (CRP), used for MIS-C diagnosis were significant in predicting MIS-C severity. Single PLT parameters, such as mean PLT volume, plateletcrit, or PLT distribution width, did not differ between the severity groups. However, we found that a combination of PLT count and the previously mentioned PLT indices had the potential to predict MIS-C severity.Conclusions: Our study emphasizes the importance of PLT in MIS-C pathogenesis and severity. It revealed that together with routine biomarkers (e.g., CBC and CRP), it could highly improve the prediction of MIS-C severity.