Serum microRNAs as Potential Biomarkers of Juvenile Idiopathic Arthritis

MicroRNAs as Biomarkers for Uveitis in Juvenile Idiopathic Arthritis

PURPOSE

Uveitis associated with juvenile idiopathic arthritis (JIA-U) is a clinically silent vision-impairing disease. Early detection and aggressive treatment are crucial for optimal visual outcome. Alterations in levels of microRNAs (miRNAs) are characteristic of autoimmune diseases. The present clinical study sought to explore the expression of miRNAs in JIA-U and their potential role as a predictive biomarker.

METHODS

MiRNA expression profiling was performed on peripheral blood mononuclear cells derived from pediatric patients with JIA, JIA-U, or other types of uveitis using the high-throughput small-RNA sequencing (on Next Generation Sequencing (NGS)). Patient- and disease-related data were retrieved from the medical files. Main outcome measure was the differential expression of miRNAs among the groups.

RESULTS

The cohort included 35 patients; 20 children with JIA-U (8 with active disease), 10 with JIA without ocular involvement, and 5 with other types of uveitis (4 with active disease). Mean age was 8.6 years; 83% were female. Nineteen patients (54%) received immunomodulatory treatment. The expression of miR-4485-3p was significantly increased in patients with JIA-U compared to patients with JIA alone (p < 0.05), with no difference between patients with active or inactive uveitis. The expression in patients with uveitis of other etiologies was similar to the expression in JIA-U patients.

CONCLUSIONS

This study demonstrates a differential expression profile of a specific miRNA in JIA patients with and without uveitis. If verified in larger studies, the findings may assist to identify JIA patients at risk to develop uveitis and to improve early detection of disease activity.

A Theoretical Link Between the GH/IGF-1 Axis and Cytokine Family in Children: Current Knowledge and Future Perspectives

BACKGROUND/OBJECTIVES

Growth in childhood and adolescence is influenced by a complex interaction of genetic, environmental, and hormonal factors, with growth hormone (GH) and insulin-like growth factor 1 (IGF-1) playing crucial roles in linear growth and development. However, chronic inflammation, often detected in situations like inflammatory bowel disease and juvenile idiopathic arthritis, can significantly disrupt the GH/IGF-1 axis, causing a relevant growth impairment.

METHODS

We conducted a retrospective review focusing on the role of cytokines in the GH-IGF-1 axis and growth.

RESULTS

Inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 have been shown to contribute to GH resistance through an array of mechanisms that involve the downregulation of GH receptors and alterations in IGF-1 metabolism. This disruption negatively impacts the growth plate, particularly by impairing chondrocyte proliferation and differentiation, which are essential for proper bone elongation. This review delves into the intricate relationship among growth, chronic inflammation, and GH-IGF-1 axis, emphasizing the contribution of inflammatory cytokines in modulating GH signaling. It also highlights how cytokines can interfere with the molecular pathways that regulate skeletal growth, ultimately leading to growth disturbances in children suffering from chronic inflammatory diseases.

CONCLUSIONS

The findings underscore the importance of controlling inflammation in affected individuals to mitigate its detrimental effects on growth and ensure that children may reach their growth full potential.

Exploring microRNA signatures in pediatric non-infectious uveitis: meta-analysis and molecular profiling of patient samples

To find a distinct non-coding RNA characteristic for idiopathic uveitis in the pediatric population. To explore the autoimmune-related miRNA expression profile in pediatric patients with idiopathic uveitis (IU) and juvenile idiopathic arthritis-associated uveitis (JIA-AU) and find a common molecular background for idiopathic uveitis and other autoimmune diseases. The expression levels of miRNAs were analyzed by quantitative real-time PCR using serum samples from patients with idiopathic uveitis (n = 8), juvenile idiopathic arthritis-associated uveitis (n = 7), and healthy controls. We selected the most promising miRNAs from the original research papers: miR-16-5p, miR-26a-5p, miR-145-5p, and miR-451a as markers for juvenile idiopathic arthritis; miR-23a-3p, miR-29a-3p, miR-140-5p, miR-193a-5p, and miR-491-5p for uveitis in the adult population; and miR-125a-5p, miR-146a-5p, miR-155-5p, miR-223-5p, and miR-223-3p characteristic for both diseases and confirm their expression changes in serum from children with idiopathic uveitis. We comprehensively reviewed the literature enrolling the papers that met the inclusion criteria (miRNA and non-infectious uveitis/juvenile idiopathic arthritis) and performed target prediction analysis of appoint miRNAs. It additionally confirmed that altered miRNAs target the immunologically involved genes. Immunological-involved miRNAs such as miR-146a-5p and miR-155-5p show diverse expression levels in different patients as they interact with multiple targets. miR-204-5p is downregulated in both patient groups compared to healthy controls. miR-204-5p and miR-155-5p are candidates for molecular markers of autoimmune uveitis. We did not identify the miRNAs specific only to idiopathic uveitis, but for the first time in the pediatric population, we confirmed that this disease entity shares a molecular basis with other autoimmune diseases. Further studies are required to elucidate the molecular interactions among miRNAs, cytokines, and transcription factors within the intricate immune response, particularly in the eye.

The epigenetic determinants for systemic juvenile idiopathic arthritis phenotyping and treatment response

BACKGROUND

Determining the role of epigenetics in systemic juvenile idiopathic arthritis (SJIA) provides an opportunity to explore previously unrecognized disease pathways and new therapeutic targets.

AIM

We aimed to identify the clinical significance of microRNAs (miRNA-26a, miRNA-223) in SJIA.

MATERIALS AND METHODS

This cross-sectional study was conducted on a group of children with SJIA attending to pediatric rheumatology clinic, at Mansoura University Children's Hospital (MUCH) from December 2021 to November 2022. Patient demographics, and clinical, and laboratory data were collected with the measurement of microRNAs by quantitative real-time PCR. The Mann-Whitney, Kruskal-Wallis, and Spearman correlation tests were used for variable comparison and correlations, besides the receiver operating characteristic (ROC) curve for microRNAs disease activity and treatment non-response discrimination.

RESULTS

Forty patients were included in the study. On comparison of miRNA-26a, and miRNA-223 levels to the clinical, assessment measures, and laboratory features, miRNA-26a was statistically higher in cases with systemic manifestations versus those without. Similarly, it was higher in children who did not fulfill the Wallace criteria for inactive disease and the American College of Rheumatology (ACR) 70 criteria for treatment response. Meanwhile, miRNA-223 was not statistically different between cases regarding the studied parameters. The best cut-off value for systemic juvenile arthritis disease activity score-10 (sJADAS-10) and the ability of miRNA-26a, and miRNA-223 to discriminate disease activity and treatment non-response were determined by the (ROC) curve.

CONCLUSION

The significant association of miRNA-26a with SJIA features points out that this molecule may be preferentially assessed in SJIA disease activity and treatment non-response discrimination.

Adult-Onset Still's Disease (AOSD): Advances in Understanding Pathophysiology, Genetics and Emerging Treatment Options

Adult-onset Still's disease (AOSD) is a multisystemic complex disorder clinically characterised by episodes of spiking fever, evanescent rash, polyarthritis or diffuse arthralgias; multiorgan involvement may develop according to the hyper-inflammatory extent. The pathogenesis of AOSD is not completely recognised. The central role of macrophage activation, which results in T helper 1 (Th1) cell cytokine activation, is well established. Pro-inflammatory cytokines such as interleukin (IL)-1, IL-6 and IL-18 play a fundamental role in disease onset and progression. The disease may develop in both children and adults with overlapping clinical features, and although several subsets depending on the clinical manifestations and the cytokines expressed have been identified, the dichotomy between systemic juvenile idiopathic arthritis (sJIA) and AOSD nowadays has been overcome, and the pathology is considered a disease continuum between ages. Various therapeutic approaches have been evaluated thus far, and different compounds are under assessment for AOSD treatment. Historically, glucocorticoids have been employed for treating systemic manifestations of Still's disease, while conventional synthetic disease modifying anti-rheumatic drugs (csDMARDs) demonstrated efficacy in controlling the articular manifestations. Currently, biological (b) DMARDs are widely employed; IL-1 inhibitors such as anakinra and canakinumab have proven to have high efficacy and an excellent safety profile and the anti-IL-6 tocilizumab is approved for sJIA, with several trials and longitudinal studies confirming its efficacy and safety. Moreover, in the light of the 'window of opportunity', new evidence showed that the earlier these treatments are initiated, the sooner clinical inactivity can be achieved. Other treatment options are being considered since several molecules involved in the disease pathophysiology can be targeted through various mechanisms. This review will provide a broad overview of AOSD pathophysiology, insights into specific organ manifestations and the currently available treatments with the identification of potential therapeutic targets involved in AOSD pathogenesis will be outlined.

MicroRNAs in Juvenile Idiopathic Arthritis: State of the Art and Future Perspectives

Juvenile Idiopathic Arthritis (JIA) represents the most common chronic pediatric arthritis in Western countries and a leading cause of disability in children. Despite recent clinical achievements, patient management is still hindered by a lack of diagnostic/prognostic biomarkers and targeted treatment protocols. MicroRNAs (miRNAs) are short non-coding RNAs playing a key role in gene regulation, and their involvement in many pathologies has been widely reported in the literature. In recent decades, miRNA's contribution to the regulation of the immune system and the pathogenesis of autoimmune diseases has been demonstrated. Furthermore, miRNAs isolated from patients' biological samples are currently under investigation for their potential as novel biomarkers. This review aims to provide an overview of the state of the art on miRNA investigation in JIA. The literature addressing the expression of miRNAs in different types of biological samples isolated from JIA patients was reviewed, focusing in particular on their potential application as diagnostic/prognostic biomarkers. The role of miRNAs in the regulation of immune responses in affected joints will also be discussed along with their potential utility as markers of patients' responses to therapeutic approaches. This information will be of value to investigators in the field of pediatric rheumatology, encouraging further research to increase our knowledge of miRNAs' potential for future clinical applications in JIA.

MicroRNA-27a-3p enhances the inflammatory phenotype of Juvenile Idiopathic Arthritis fibroblast-like synoviocytes

BACKGROUND

Juvenile Idiopathic Arthritis (JIA) is the most prevalent chronic pediatric rheumatic disorder. In joints of JIA patients, aggressive phenotypic changes in fibroblast-like synoviocytes (FLS) of the synovial lining play a key role in inflammation. MicroRNAs are dysregulated in rheumatoid arthritis and JIA, including miR-27a-3p. However, it is not understood if miR-27a-3p, enriched in JIA synovial fluid (SF) and leukocytes, alters FLS function.

METHODS

Primary JIA FLS cells were transfected with a miR-27a-3p mimic or a negative control microRNA (miR-NC) and stimulated with pooled JIA SF or inflammatory cytokines. Viability and apoptosis were analyzed by flow cytometry. Proliferation was evaluated using a ³H-thymidine incorporation assay. Cytokine production was assessed by qPCR and ELISA. Expression of TGF-β pathway genes was determined using a qPCR array.

RESULTS

MiR-27a-3p was constitutively expressed in FLS. Overexpression of miR-27a-3p caused increased interleukin-8 secretion in resting FLS, and interleukin-6 was elevated in SF-activated FLS compared to miR-NC. Furthermore, stimulation with pro-inflammatory cytokines augmented FLS proliferation in miR-27a-3p-transfected FLS relative to miR-NC. Expression of multiple TGF-β pathway genes was modulated by overexpression of miR-27a-3p.

CONCLUSIONS

MiR-27a-3p significantly contributes to FLS proliferation and cytokine production, making it a potential candidate for epigenetic therapy that targets FLS in arthritis.

Study of the shared gene signatures of polyarticular juvenile idiopathic arthritis and autoimmune uveitis

Objective

To explore the shared gene signatures and potential molecular mechanisms of polyarticular juvenile idiopathic arthritis (pJIA) and autoimmune uveitis (AU).

Method

The microarray data of pJIA and AU from the Gene Expression Omnibus (GEO) database were downloaded and analyzed. The GEO2R tool was used to identify the shared differentially expressed genes (DEGs) and genes of extracellular proteins were identified among them. Then, weighted gene co-expression network analysis (WGCNA) was used to identify the shared immune-related genes (IRGs) related to pJIA and AU. Moreover, the shared transcription factors (TFs) and microRNAs (miRNAs) in pJIA and AU were acquired by comparing data from HumanTFDB, hTFtarget, GTRD, HMDD, and miRTarBase. Finally, Metascape and g: Profiler were used to carry out function enrichment analyses of previously identified gene sets.

Results

We found 40 up-regulated and 15 down-regulated shared DEGs via GEO2R. Then 24 shared IRGs in positivity-related modules, and 18 shared IRGs in negatively-related modules were found after WGCNA. After that, 3 shared TFs (ARID1A, SMARCC2, SON) were screened. And the constructed TFs-shared DEGs network indicates a central role of ARID1A. Furthermore, hsa-miR-146 was found important in both diseases. The gene sets enrichment analyses suggested up-regulated shared DEGs, TFs targeted shared DEGs, and IRGs positivity-correlated with both diseases mainly enriched in neutrophil degranulation process, IL-4, IL-13, and cytokine signaling pathways. The IRGs negatively correlated with pJIA and AU mainly influence functions of the natural killer cell, cytotoxicity, and glomerular mesangial cell proliferation. The down-regulated shared DEGs and TFs targeted shared DEGs did not show particular functional enrichment.

Conclusion

Our study fully demonstrated the flexibility and complexity of the immune system disorders involved in pJIA and AU. Neutrophil degranulation may be considered the shared pathogenic mechanism, and the roles of ARID1A and MiR-146a are worthy of further in-depth study. Other than that, the importance of periodic inspection of kidney function is also noteworthy.

Differentially Expressed Inflammation-Regulating MicroRNAs in Oligoarticular Juvenile Idiopathic Arthritis

OBJECTIVE

To evaluate microRNA expression in synovial fluid (SF), plasma, and leukocytes from patients with juvenile idiopathic arthritis (JIA).

METHODS

MicroRNA expression in pooled JIA plasma and SF was assessed by absolute quantitative droplet digital PCR array. The results were validated in individual patient samples. MicroRNA content in leukocytes and extracellular vesicles was evaluated by real-time PCR in JIA blood and SF. Blood microRNA expression was compared with healthy controls (HCs). Principal component analysis was used to profile JIA plasma and SF microRNAs, and the potential biological consequences of microRNA dysregulation were investigated by pathway analysis.

RESULTS

MiR-15a-5p and miR-409-3p levels were higher in JIA plasma than in HC plasma. JIA SF contained elevated levels of miR-21-5p, miR-27a-3p, miR-146b-5p, miR-155-5p, and miR-423-5p, and decreased miR-192-5p and miR-451a, compared to JIA plasma. Extracellular vesicle analysis demonstrated variable encapsulation among selected microRNAs, with only miR-155-5p being represented substantially in extracellular vesicles. SF leukocytes also had higher expression of miR-21-5p, miR-27a-3p, miR-146b-5p, and miR-155-5p, and lower expression of miR-409-3p and miR-451a, relative to blood. No differences were observed between JIA and HC blood leukocytes. Clusters of microRNAs were commonly altered in JIA joint fluid and leukocytes compared to JIA blood samples. In silico analysis predicted that differentially expressed microRNAs in JIA target the transforming growth factor (TGF)-β pathway.

CONCLUSION

The expression of multiple microRNAs is dysregulated in JIA both locally and systemically, which may inhibit the TGF-β pathway. These findings advance our knowledge of JIA immunopathogenesis and may lead to the development of targeted therapies.

The effects of circulating MIR22-3p and MIR16-1-3p levels in different stages of subacute thyroiditis

Subacute thyroiditis (SAT) is an inflammatory thyroid disease with a frequency is 5% among all thyroid diseases. miRNAs are endogenous, non-coding RNAs ranging in length from 19 to 25 nucleotides. They play an important role in the posttranscriptional regulation of gene expression. In this study, we aimed to investigate whether the expression levels of two circulating miRNAs, MIR22 and MIR16-1, can be used as a parameter in the diagnosis and follow-up of SAT disease. Fifty patients diagnosed with SAT and 41 healthy controls were included in this study. Expression levels of miRNAs were determined by real time-PCR method. Expression data of miRNAs were calculated by fold change (2^-ΔΔCt) method. The statistical significance of miRNA expression was evaluated by t-test. The expression levels of MIR22-3p and MIR16-1-3p were not found to be statistically different between SAT patients and controls and also between the patients in different stages (hyperthyroid, euthyroid, and hypothyroid) of the disease. According to correlation analyses, we observed a positive strong correlation between erythrocyte sedimentation rate (ESR) and the expression levels of MIR22-3p and MIR16-1-3p (r = 0.960, p = 0.000 and r = 0.865, p = 0.006, respectively), and a positive strong correlation between fT4 and the expression levels of MIR22-3p in SAT patients in euthyroid stage (r = 0.712, p = 0.047). In this study, we showed that the expression levels of MIR22-3p and MIR16-1-3p have correlation with clinical characteristics of SAT disease. Our results suggest that MIR22 and MIR16-1 may be effective in the pathogenesis of SAT.

The role of epigenetics in childhood autoimmune diseases with hematological manifestations

Autoimmune diseases with hematological manifestations are often characterized by chronicity and relapses despite treatment, and the underlying pathogenetic mechanisms remain unknown. Epigenetic alterations play a vital role in the deregulation of immune tolerance and the development of autoimmune diseases. In recent years, study of epigenetic mechanisms in both adult and childhood autoimmune disorders has been seeking to explain the pathophysiology of these heterogeneous diseases and to elucidate the interaction between genetic and environmental factors. Various mechanisms, including DNA methylation, histone modifications (chromatin remodeling), and noncoding RNAs (ncRNAs), have been studied extensively in the context of autoimmune diseases. This paper summarizes the epigenetic patterns in some of the most common childhood autoimmune disorders with hematological manifestations, based on epigenetic studies in children with primary immune thrombocytopenia (ITP), systemic lupus erythematosus (SLE), and juvenile idiopathic arthritis (JIA). Research findings indicate that methylation changes in genes expressed on T cells, modifications at a variety of histone sites, and alterations in the expression of several ncRNAs are involved in the pathogenesis of these diseases. These mechanisms not only determine the development of these diseases but also affect the severity of the clinical presentation and biochemical markers. Further studies will provide new tools for the prevention and diagnosis of childhood autoimmune disorders, and possible novel treatment options.

MicroRNA expression profiling of cerebrospinal fluid/serum exosomes in children with human herpesvirus 6-associated encephalitis/encephalopathy by high-throughput sequencing

Primary human herpesvirus 6 (HHV-6) infection is sometimes accompanied by acute encephalopathy with reduced subcortical diffusion (AED) in immunocompetent children. We investigated exosomal microRNA (miRNA) expression profiles in cerebrospinal fluid (CSF) and sera of patients with HHV-6-associated AED (n = 5) and febrile seizure (FS) (n = 5) using high-throughput sequencing. A total of 176 and 663 miRNAs were identified in CSF and serum exosomes, respectively. Comparative analysis determined that some miRNAs (miR-381-3p, miR-155) were exclusively expressed in the CSF exosomes of AED but not of FS patients, suggesting their potential application as novel diagnostic biomarkers for AED.

Responses of patients with juvenile idiopathic arthritis to methotrexate: a genomic outlook

INTRODUCTION

Juvenile idiopathic arthritis (JIA) is a chronic disease characterized by persistent joint inflammation. JIA is the most common pediatric chronic rheumatic disease and no curative therapy is currently available. Methotrexate (MTX) is an important treatment for JIA even though a high inter-individual variability in response is observed in patients. Among the factors of this variability, genetics and epigenetics might play an important role.

AREAS COVERED

This review summarizes the results of pharmacogenetic and pharmacoepigenetic studies regarding MTX response in JIA. Studies considering epigenetic factors in JIA patients are still very limited, therefore this review includes also studies performed in adult patients with rheumatoid arthritis. Moreover, the relevance of biomarkers measured in blood or urine of JIA patients in relation to MTX treatment is discussed.

EXPERT OPINION

Nowadays, even though many pharmacogenomics studies have been published, a specific genetic marker predictor of MTX efficacy or adverse events has not yet been identified. Encouraging results are available and great expectations rely on the study of epigenetics. Future studies are needed in order to identify genetic and epigenetic biomarkers that can be implemented in the clinical practice.

miR-23a contributes to T cellular redox metabolism in juvenile idiopathic oligoarthritis

OBJECTIVE

Juvenile idiopathic arthritis (JIA) is a chronic inflammatory disease of unknown origin. The regulation of inflammatory processes involves multiple cellular steps including mRNA transcription and translation. Different miRNAs tightly control these processes. We aimed to determine the roles of specific miRNAs within JIA pathogenesis.

METHODS

We performed a global miRNA expression analysis in parallel in cells from the arthritic joint and peripheral blood of oligoarticular JIA patients and healthy controls. QRT-PCR analysis was used to verify expression of miRNA in T cells. Ex vivo experiments and flow cytometric analyses were used to analyze proliferation and redox metabolism.

RESULTS

Global miRNA expression analysis demonstrated a different composition of miRNA expression at the site of inflammation compared with peripheral blood. Bioinformatic analysis of predicted miRNA target genes suggest a huge overrepresentation of genes involved in metabolic and oxidative stress pathways in the inflamed joint. Despite enhanced ROS levels within the local inflammatory milieu, JIA T cells are hyperproliferative and reveal an overexpression of miR-23a, which is an inhibitor of PPIF, the regulator of mitochondrial ROS escape. Mitochondrial ROS escape is diminished in JIA T cells resulting in their prolonged survival.

CONCLUSION

Our data suggest that miRNA dependent mitochondrial ROS shuttling might be a mechanism that contributes to T cell regulation in JIA at the site of inflammation.

Novel biomarkers for prediction of outcome and therapeutic response in juvenile idiopathic arthritis

INTRODUCTION

The search for biomarkers in juvenile idiopathic arthritis (JIA) is a promising and rapidly expanding field of investigation. The biomarkers identified so far may help to dissect the clinical heterogeneity of the illness, measure the level of disease activity, predict clinical remission, relapse, response to medications, course over time, complications, and forestall disease flares.

AREAS COVERED

We provide a summary of the most recent advances in the development and application of biomarkers in JIA. We performed a PubMed search for significant articles combining predetermined keywords related to biomarkers in non-systemic and systemic JIA, chronic uveitis, and macrophage activation syndrome (MAS). The biomarkers available or under study are presented and discussed separately for non-systemic and systemic subtypes and for the two main disease complications, uveitis and MAS.

EXPERT OPINION

The incorporation of valid and reliable biomarkers in standard clinical care may help to design better patient-tailored treatment regimens and to improve the therapeutic strategies based on the treat-to-target approach. The establishment of biomarkers that predict the risk of disease flare may lead to define the optimal modalities for treatment discontinuation after the achievement of clinical remission.

The Potential Importance of MicroRNAs as Novel Indicators How to Manage Patients with Juvenile Idiopathic Arthritis More Effectively

Small, noncoding sequences of ribonucleic acid called microRNAs (miRNAs, miR) are functioning as posttranscriptional regulators of gene expression. As they draw increasing attention of rheumatologists, there is a growing body of evidence concerning specific molecules that may affect the long-term care of patients with inflammatory arthritides. Findings involving children with juvenile idiopathic arthritis (JIA) are still limited though. The aim of the study was to browse the available data on microRNAs which may be utilized as potential biomarkers helpful in diagnosing and monitoring JIA patients. The review contains a brief summary on the most studied sequences: miR-16, miR-125a-5p, miR-146a, miR-155, and miR-223. It is complemented with other miRNAs possibly relevant for JIA (miR-145, miR-23b, miR-27a, and miR-204) and discussion on challenges for using miRNAs in pediatric rheumatology (particularly, issues regarding specificity of biomarkers and measurements involving synovial fluid).

The Multi-Omics Architecture of Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is highly heterogeneous in terms of etiology and clinical presentation with ambiguity in JIA classification. The advance of high-throughput omics technologies in recent years has gained us significant knowledge about the molecular mechanisms of JIA. Besides a minor proportion of JIA cases as monogenic, most JIA cases are polygenic disease caused by autoimmune mechanisms. A number of HLA alleles (including both HLA class I and class II genes), and 23 non-HLA genetic loci have been identified of association with different JIA subtypes. Omics technologies, i.e., transcriptome profiling and epigenomic analysis, contributed significant knowledge on the molecular mechanisms of JIA in addition to the genetic approach. New molecular knowledge on different JIA subtypes enables us to reconsider the JIA classification, but also highlights novel therapeutic targets to develop a cure for the devastating JIA.

Regulation of JAK/STAT signal pathway by miR-21 in the pathogenesis of juvenile idiopathic arthritis

BACKGROUND

Overexpression of the components of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signalling pathway is the key factor of the pathogenic mechanisms underlying systemic juvenile idiopathic arthritis (sJIA). The study aims to investigate the association between miR-21 and the JAK/STAT signal pathway in JIA.

METHODS

Total RNA was extracted from peripheral blood mononuclear cells (PBMCs) in active JIA patients. The relative expressions of miR-21, STAT3 and suppressor of cytokine signalling 3 in PBMCs were measured by real-time polymerase chain reaction and their expressions were measured by western blotting and dual-luciferase reported assay. Rheumatoid arthritis fibroblast-like synovial cell (RASF) was stimulated to become to osteoclasts using macrophage colony-stimulating factor (M-CSF) and factors that can impact on their differentiation ability were identified through the transfection of LV3-miR-21. The expression of STAT3/p-STAT3 was measured by western blot, and the levels of interleukin (IL)-17A, p65, matrix metalloproteinases (MMP)-3, MMP-4 and receptor activator of nuclear factor-κB after the LV3-miR-21 transfection were tested by enzyme-linked immunosorbent assay. Finally, the miR-21 targeted STAT3 gene was detected by the dual-luciferase reported assay.

RESULTS

The expression of miR-21 was significantly lower in JIA patients than in healthy control (P < 0.05). The level of STAT3 was increased in PBMCs of JIA group compared with control group (P < 0.05). Furthermore, the expression levels of miR-21 in sJIA and polyarticular JIA groups were negatively correlated with STAT3 (r = - 0.5854/r = - 0.6134, P < 0.05). The expression of STAT3 changed little in PBMCS after the stimulation of IL-6 and not in RASFs with transfection of LV3-miR-21. The expression of p-STAT3 decreased after the stimulation of IL-6 in RASFs transfected by LV3-miR-21 (P < 0.05). RASFs were induced into osteoclasts using M-CSF. The number of osteoclasts as determined by tartrate-resistant acid phosphatase staining was significantly lower in group miR-21 mimics as compared with the negative control group (P < 0.05).

CONCLUSIONS

We showed that expression of miR-21 was significantly lower in JIA patients compared with healthy control. MiR-21 might affect the JAK/STAT signal pathway by suppressing the expression of STAT3 and phosphorylation of STAT3. MiR-21 could inhibit the production of osteoclasts induced from RASFs by M-CSF.

Synovial-Fluid miRNA Signature for Diagnosis of Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory rheumatism in childhood; microRNAs (miRNAs) have been proposed as diagnostic biomarkers. Although joints are the primary targets for JIA, a synovial fluid-based miRNA signature has never been studied. We aim to identify miRNA biomarkers in JIA by comparing synovial fluid and serum samples from children with JIA and K. kingae septic arthritis (SA). With next-generation high-throughput sequencing, we measured the absolute levels of 2083 miRNAs in synovial fluid and serum from an exploratory cohort of children and validated differentially expressed miRNAs in a replication study by using RT-qPCR. We identified a 19-miRNA signature only in synovial fluid samples that was significantly deregulated, with at least 2-fold change in expression, in JIA versus SA (p < 0.01). The combination of miR-6764-5p, miR-155, and miR-146a-5p expression in synovial fluid yielded an area under the receiver operating characteristic curve of 1 (95% CI 0.978 to 1), thereby perfectly differentiating JIA from SA in children. We propose, for the first time, a synovial fluid-specific miRNA signature for JIA and associated signaling pathways that may indicate potential biomarkers to assist in the classification and differential diagnosis of JIA and help in understanding JIA pathogenesis.

Assessment of Circulating Microribonucleic Acids in Patients With Familial Mediterranean Fever

Objectives

This study aims to evaluate the plasma expression of microribonucleic acids (miRNAs) that may be associated with the pathogenesis of familial Mediterranean fever (FMF).

Patients and methods

Thirty patients with FMF (18 males, 12 females; mean age 9.1±4.7 years; range, 3 to 15.5 years) and 30 age- and sex-matched healthy children (18 males, 12 females; mean age 9.5±4.6 years; range, 4 to 16.5 years) were included in this study. The plasma levels of four candidate miRNAs (miRNA-16, miRNA-155, miRNA-204 and miRNA-451) were measured in all subjects. The plasma levels of miRNAs were analyzed with real- time polymerase chain reaction in attack and remission periods of patients and healthy controls (HCs).

Results

Plasma miRNA-204 levels of FMF patients were decreased 6.5 fold in remission period compared to HCs (p<0.001). This decrease was more prominent in M694V mutation carriers. Plasma miRNA-155 levels of FMF patients were lower in remission period (p=0.03).

Conclusion

Our findings showed significant alterations in the plasma expression of miRNA-155 and miRNA-204 in FMF patients compared to HCs. Our data suggest that miRNA-155 and miRNA-204 may be related to the pathogenesis of FMF. Further comprehensive and functional researches may help to clarify the role of miRNAs in FMF and elucidate the pathogenesis of the disease.

LC-MS Analysis of Serum for the Metabolomic Investigation of the Effects of Pulchinenoside b4 Administration in Monosodium Urate Crystal-Induced Gouty Arthritis Rat Model

Gouty arthritis (GA) is commonly caused by deposition of monosodium urate (MSU) crystals within the joint capsule, bursa, cartilage, bone, or other periarticular tissues after chronic hyperuricemia. Clinically, GA is characterized by acute episodes of joint inflammation, which is most frequently encountered in the major joints, and also has a significant impact on quality of life. Pulchinenoside b4(P-b4) has a wide range of biological activities, including antitumor, anti-inflammatory, antiviral and immunomodulatory activities. Currently, the anti-GA activity and metabolomic profiles after being treated by P-b4 have not been reported. In this paper, for the first time, we have performed a non-targeted metabolomics analysis of serum obtained from an MSU crystal-induced GA rat model intervened by P-b4, using ultra-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry. In this study, the main pharmacodynamics of different dosing methods and dosages of P-b4 was firstly investigated. Results have shown that P-b4 possesses high anti-inflammatory activity. These results demonstrated changes in serum metabolites with 32 potential biomarkers. Arachidonic acid, sphingolipid, and glycerophospholipid metabolism are considered to be the most relevant metabolic pathway with P-b4 treatment effect in this study. Moreover, the changes of metabolites and the self-extinction of model effects within 24 h reveals important information for GA diagnostic criteria: The regression of clinical symptoms or the decline of some biochemical indicators cannot be regarded as the end point of GA treatment. Furthermore, our research group plans to conduct further metabolomics research on the clinical course of GA.

Micro-RNAs in inflammatory arthritis: From physiopathology to diagnosis, prognosis and therapeutic opportunities

Micro-RNAs are an area of research exponentially expanding over the past years. These small sequences of 20-22 nucleotides have a strong role as post-transcriptional regulators of gene expression. Inflammatory arthritis pathophysiology involves various key players from innate to adaptive immunity, as well as various signalling pathways of inflammation. In this review, we discuss how micro-RNAs are involved in rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis and juvenile inflammatory arthritis, from pre-clinical phases to established diseases. We describe mi-RNAs key roles in fibroblast like synoviocytes migration, proliferation, apoptosis and cytokine production, in macrophages polarization, as well as in B cells and T cell proliferation and differentiation, with a special emphasis on Treg/Th17 imbalance. We finally discuss the application of these findings in pre-clinical models and highlight opportunities and limits of a therapeutic approach using mi-RNAs agonists or antagonists.

microRNA diagnostic panel for Alzheimer's disease and epigenetic trade-off between neurodegeneration and cancer

microRNAs (miRNAs) have been extensively studied as potential biomarkers for Alzheimer's disease (AD). Their profiles have been analyzed in blood, cerebrospinal fluid (CSF) and brain tissue. However, due to the high variability between the reported data, stemming from the lack of methodological standardization and the heterogeneity of AD, the most promising miRNA biomarker candidates have not been selected. Our literature review shows that out of 137 miRNAs found to be altered in AD blood, 36 have been replicated in at least one independent study, and out of 166 miRNAs reported as differential in AD CSF, 13 have been repeatedly found. Only 3 miRNAs have been consistently reported as altered in three analyzed specimens: blood, CSF and the brain (hsa-miR-146a, hsa-miR-125b, hsa-miR-135a). Nonetheless, all 36 repeatedly differential miRNAs in AD blood are promising as components of the diagnostic panel. Given their predicted functions, such miRNA panel may report multiple pathways contributing to AD pathology, enabling the design of personalized therapies. In addition, the analysis revealed that the miRNAs dysregulated in AD overlap highly with miRNAs implicated in cancer. However, the directions of the miRNA changes are usually opposite in cancer and AD, indicative of an epigenetic trade-off between the two diseases.

Evaluation of plasma microRNA expressions in patients with juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease of childhood, yet its etiology is unknown. It is known that microribonucleic acids (miRNAs) play a role in immunoregulation. We aimed to evaluate the plasma expression of some candidate miRNAs that are associated with the pathogenesis of autoimmunity. Thirty-one patients diagnosed with JIA and age-sex-matched 31 healthy children were enrolled for the study. The plasma levels of four candidate miRNAs (miRNA-16, miRNA-155, miRNA-204, and miRNA-451), which are known to be associated with autoimmunity, were examined in all the subjects. The plasma levels of miRNAs were measured with real-time PCR in the patients in active and inactive periods and in the healthy controls. The groups were compared with each other. The plasma miRNA-155 levels were found to increase in the JIA patients compared to the healthy controls, and it was statistically more significant in the inactive period. We found that the JIA patients had the higher levels of miRNA-16 and the lower levels of miRNA-204/miRNA-451 expressions compare with the control group, but there was no statistically significant difference. A statistically significant decrease in the plasma levels of miRNA-204 was found in the patients that were in inactive disease with only methotrexate therapy. The plasma miRNA expressions were compared in the JIA subtypes, and it was observed that miRNA-204 levels were higher in polyarticular JIA and miRNA-451 levels were higher in enthesitis-related arthritis without statistical significance. The significant alterations in the plasma expression of miRNA-155 and miRNA-204 suggest to us that these molecules may be related to the pathogenesis of JIA. More comprehensive and functional researches about the role of these molecules are needed in this regard.

microRNA-200a-3p enhances mitochondrial elongation by targeting mitochondrial fission factor

Mitochondria play pivotal roles in the ATP production, apoptosis and generation of reactive oxygen species. Although dynamic regulation of mitochondria morphology is a critical step to maintain cellular homeostasis, the regulatory mechanisms are not yet fully elucidated. In this study, we identified miR-200a-3p as a novel regulator of mitochondrial dynamics by targeting mitochondrial fission factor (MFF). We demonstrated that the ectopic expression of miR-200a-3p enhanced mitochondrial elongation, mitochondrial ATP synthesis, mitochondrial membrane potential and oxygen consumption rate. These results indicate that miR-200a-3p positively regulates mitochondrial elongation by downregulating MFF expression.

MicroRNA networks associated with active systemic juvenile idiopathic arthritis regulate CD163 expression and anti-inflammatory functions in macrophages through two distinct mechanisms

Systemic juvenile idiopathic arthritis (SJIA) is a severe childhood arthropathy with features of autoinflammation. Monocytes and macrophages in SJIA have a complex phenotype with both pro- and anti-inflammatory properties that combine features of several well characterized in vitro conditions used to activate macrophages. An important anti-inflammatory phenotype is expression of CD163, a scavenger receptor that sequesters toxic pro-inflammatory complexes that is highly expressed in both active SJIA and macrophage activation syndrome (MAS). CD163 is most strongly up-regulated by IL-10 (M(IL-10)), and not by other conditions that reflect features seen in SJIA monocytes such as M(LPS+IC). MicroRNA plays key roles in integrating cellular signals such as those in macrophage polarization, and as such we hypothesize microRNAs regulate macrophage functional responses in SJIA including CD163 expression. We find that 2 microRNAs previously found to be elevated in active SJIA, miR-125a-5p and miR-181c, significantly reduced macrophage CD163 expression through 2 distinct mechanisms. Neither microRNA was elevated in M(IL-10) with robust CD163 expression, but were instead induced in M(LPS+IC) where they restricted CD163 mRNA expression. Mir-181 species directly targeted CD163 mRNA for degradation. In contrast, miR-125a-5p functions indirectly, as transcriptome analysis of miR-125a-5p overexpression identified "cytokine-cytokine receptor interactions" as the most significantly repressed gene pathway, including decreased IL10RA, required for IL-10-mediated CD163 expression. Finally, overexpression of miR-181c inhibited CD163 anti-inflammatory responses to hemoglobin or high mobility group box 1 (HMGB1) complexes. Together, these data show that microRNA utilizes multiple mechanisms to integrate well-characterized polarization phenotypes and regulate macrophage functional properties seen in SJIA.

MicroRNA-induced silencing in epilepsy: Opportunities and challenges for clinical application

MicroRNAs are master regulators of gene expression. Single microRNAs influence multiple proteins within diverse molecular pathways and networks. Therefore, changes in levels or activity of microRNAs can have profound effects on cellular function. This makes dysregulated microRNA-induced silencing an attractive potential disease mechanism in complex disorders like epilepsy, where numerous cellular pathways and processes are affected simultaneously. Indeed, several years of research in rodent models have provided strong evidence that acute or recurrent seizures change microRNA expression and function. Moreover, altered microRNA expression has been observed in brain and blood from patients with various epilepsy disorders, such as tuberous sclerosis. MicroRNAs can be easily manipulated using sense or antisense oligonucleotides, opening up opportunities for therapeutic intervention. Here, we summarize studies using these techniques to identify microRNAs that modulate seizure susceptibility, describe protein targets mediating some of these effects, and discuss cellular pathways, for example neuroinflammation, that are controlled by epilepsy-associated microRNAs. We critically assess current gaps in knowledge regarding target- and cell-specificity of microRNAs that have to be addressed before clinical application as therapeutic targets or biomarkers. The recent progress in understanding microRNA function in epilepsy has generated strong momentum to encourage in-depth mechanistic studies to develop microRNA-targeted therapies. Developmental Dynamics 247:94-110, 2018. © 2017 Wiley Periodicals, Inc.

Microarray analysis of circulating microRNAs in familial Mediterranean fever

OBJECTIVES

Familial Mediterranean fever (FMF) is an autoinflammatory disease caused by mutations in MEFV. Mutations in exon 10 are associated with typical FMF phenotypes, whereas the pathogenic role of variants in exons 2 and 3 remains uncertain. Recent evidence suggests that circulating microRNAs (miRNAs) are potentially useful biomarkers in several diseases. Therefore, their expression was assessed in FMF.

METHODS

The subjects were 24 patients with FMF who were between attacks: eight with exon 10 mutations (group A), eight with exon 3 mutations (group B), and eight without exon 3 or 10 mutations (group C). We also investigated eight cases of PFAPA as disease controls. Exosome-rich fractionated RNA was subjected to miRNA profiling by microarray.

RESULTS

Using the expression patterns of 26 miRNAs, we classified FMF (groups A, B, and C) and PFAPA with 78.1% accuracy. In FMF patients, groups A and B, A and C, and B and C were distinguished with 93.8, 87.5, and 100% accuracy using 24, 30, and 25 miRNA expression patterns, respectively.

CONCLUSIONS

These findings suggest that expression patterns of circulating miRNAs differ among FMF subgroups based on MEFV mutations between FMF episodes. These patterns may serve as a useful biomarker for detecting subgroups of FMF.

Inflammatory Diseases and Growth: Effects on the GH-IGF Axis and on Growth Plate

This review briefly describes the most common chronic inflammatory diseases in childhood, such as cystic fibrosis (CF), inflammatory bowel diseases (IBDs), juvenile idiopathic arthritis (JIA), and intrauterine growth restriction (IUGR) that can be considered, as such, for the changes reported in the placenta and cord blood of these subjects. Changes in growth hormone (GH) secretion, GH resistance, and changes in the insulin-like growth factor (IGF) system are described mainly in relationship with the increase in nuclear factor-κB (NF-κB) and pro-inflammatory cytokines. Changes in the growth plate are also reported as well as a potential role for microRNAs (miRNAs) and thus epigenetic changes in chronic inflammation. Many mechanisms leading to growth failure are currently known; however, it is clear that further research in the field is still warranted.

Monocyte MicroRNA Expression in Active Systemic Juvenile Idiopathic Arthritis Implicates MicroRNA-125a-5p in Polarized Monocyte Phenotypes

OBJECTIVE

Systemic juvenile idiopathic arthritis (JIA) is an inflammatory disease of childhood in which cells of the monomyelocytoid lineage are thought to be key effector cells. Monocytes from patients with systemic JIA have a distinct phenotype, with features of both M1 and M2 alternative activation. MicroRNAs are critical regulators of monocyte polarization and function, but cellular microRNAs in systemic JIA have not been examined systematically.

METHODS

MicroRNA TaqMan arrays were used to determine the expression profiles of monocytes from children with systemic JIA. Expression of microRNA-125a-5p (miR-125a-5p) and its contribution to monocyte polarization were examined using in vitro-polarized THP-1 cells and primary human monocytes.

RESULTS

A total of 110 microRNAs were found to be differentially expressed in monocytes from patients with active systemic JIA, including molecules implicated in rheumatoid arthritis pathogenesis, cytokine production, and monocyte polarization. MicroRNA-125a-5p was identified as being highly up-regulated in monocytes from children with active systemic JIA, as compared to those from children with clinically inactive JIA or those with active polyarticular JIA, and correlated with systemic features of the disease. In vitro, monocyte miR125a-5p expression was increased after polarization under M2b or M2c conditions. Inhibition of miR-125a-5p showed that this microRNA contributed to full polarization of M2b regulatory macrophages. In contrast, miR-125a-5p overexpression enhanced M2b polarization and altered other polarized populations, including increasing the production of M2 markers. Indeed, in vitro overexpression of this microRNA altered the macrophage phenotype toward that observed in systemic JIA.

CONCLUSION

Children with active systemic JIA have profound alterations in the expression of microRNAs that are implicated in monocyte function and polarization. One of these microRNAs, miR-125a-5p, is also a regulator of immunoregulatory M2b macrophages.

A novel reactive epitope-based antigen targeted by serum autoantibodies in oligoarticular and polyarticular juvenile idiopathic arthritis and development of an electrochemical biosensor

Currently, there are no specific markers for juvenile idiopathic arthritis (JIA) diagnosis, which is based on clinical symptoms and some blood tests for diseases' exclusion. Aiming to select new epitope-based antigens (mimotopes) that could recognize circulating autoantibodies in most JIA forms, we screened a phage displayed random peptide library against IgG antibodies purified from serum of JIA patients. ELISA assay was carried out to confirm immunoreactivity of selected peptides against sera IgG antibodies from JIA patients, healthy children and patients with other autoimmune diseases. The mimotope PRF+1 fused to phage particles was able to efficiently discriminate JIA patients from controls, and for this reason was chosen to be chemically synthesized for validation in a larger sample size. The synthetic peptide was immobilized onto bioelectrodes' surface for antibody detection by electrochemical analyses through differential pulse voltammetry. The PRF+1 synthetic peptide has efficiently discriminated JIA patients from control groups (p<0.0001) with a very good accuracy (AUC>0.84; sensitivity=61%; specificity=91%). The electrochemical platform proved to be fast, low cost and effective in detecting anti-PRF+1 antibodies from JIA patients compared to healthy controls (p=0.0049). Our study describes a novel and promising epitope-based biomarker for JIA diagnosis that can become a useful tool for screening tests, which was successfully incorporated onto an electrochemical biosensor and could be promptly used in field diagnostics.