Repression of CTSG, ELANE and PRTN3-mediated histone H3 proteolytic cleavage promotes monocyte-to-macrophage differentiation.

Chromatin undergoes extensive reprogramming during immune cell differentiation. Here we report the repression of controlled histone H3 amino terminus proteolytic cleavage (H3ΔN) during monocyte-to-macrophage development. This abundant histone mark in human peripheral blood monocytes is catalyzed by neutrophil serine proteases (NSPs) cathepsin G, neutrophil elastase and proteinase 3. NSPs are repressed as monocytes mature into macrophages. Integrative epigenomic analysis reveals widespread H3ΔN distribution across the genome in a monocytic cell line and primary monocytes, which becomes largely undetectable in fully differentiated macrophages. H3ΔN is enriched at permissive chromatin and actively transcribed genes. Simultaneous NSP depletion in monocytic cells results in H3ΔN loss and further increase in chromatin accessibility, which likely primes the chromatin for gene expression reprogramming. Importantly, H3ΔN is reduced in monocytes from patients with systemic juvenile idiopathic arthritis, an autoinflammatory disease with prominent macrophage involvement. Overall, we uncover an epigenetic mechanism that primes the chromatin to facilitate macrophage development.

C13orf31 (FAMIN) is a central regulator of immunometabolic function.

Single-nucleotide variations in C13orf31 (LACC1) that encode p.C284R and p.I254V in a protein of unknown function (called 'FAMIN' here) are associated with increased risk for systemic juvenile idiopathic arthritis, leprosy and Crohn's disease. Here we set out to identify the biological mechanism affected by these coding variations. FAMIN formed a complex with fatty acid synthase (FASN) on peroxisomes and promoted flux through de novo lipogenesis to concomitantly drive high levels of fatty-acid oxidation (FAO) and glycolysis and, consequently, ATP regeneration. FAMIN-dependent FAO controlled inflammasome activation, mitochondrial and NADPH-oxidase-dependent production of reactive oxygen species (ROS), and the bactericidal activity of macrophages. As p.I254V and p.C284R resulted in diminished function and loss of function, respectively, FAMIN determined resilience to endotoxin shock. Thus, we have identified a central regulator of the metabolic function and bioenergetic state of macrophages that is under evolutionary selection and determines the risk of inflammatory and infectious disease.

LACC1 deficiency leading to juvenile arthritis and anemia.

OBJECTIVE: Juvenile arthritis caused by loss-of-function LACC1 mutations is characterized by early onset of symmetric and chronic arthritis, associated with an elevation of inflammatory markers. We aimed to describe serum cytokine levels, explore the type I interferon pathway, and evaluate the efficacy of treatment in a patient presenting with polyarthritis and anemia caused by novel compound heterozygous variations in LACC1. METHODS: Clinical data of a patient with compound heterozygous variations in LACC1 was collected. Serum cytokine levels and IFN-stimulated cytokine genes were analyzed at diagnosis, at disease flare, and after treatment. Full-length cDNA of LACC1 was checked by RNA analysis. Single-cell RNA sequencing was performed in PBMCs. RESULTS: Two novel variants in the LACC1 gene were identified in a patient presenting with polyarthritis and anemia. LACC1-cDNA was normally expressed in the healthy control, the target production at 1384 bp was not observed in the patient. Compared to nine patient controls with non-systemic juvenile idiopathic arthritis, serum interleukin(IL)-6 level was significantly elevated in the affected patient. The median IFN score for the patient, her mother, and controls were 118, 8, and 4.9, respectively. The combined treatment of JAK inhibitors with prednisone or tocilizumab led to a complete response, including remission of joint symptoms, resolution of anemia, reduced expression of IFN-stimulated cytokine genes, and normalized levels of inflammatory markers, including CRP, ESR, SAA, and serum IL-6. CONCLUSION: LACC1 may play a crucial role in multiple inflammatory signaling pathways. The combination therapy of JAK inhibitors and tocilizumab may be effective for a subset of refractory patients.

Revealing novel genomic insights and therapeutic targets for juvenile idiopathic arthritis through omics.

BACKGROUND: The genetic architecture of JIA remains only partially comprehended. There is a clear imperative for continued endeavours to uncover insights into the underlying causes of JIA. METHODS: This study encompassed a comprehensive spectrum of endeavours, including conducting a JIA genome-wide association study (GWAS) meta-analysis that incorporated data from 4550 JIA cases and 18 446 controls. We employed in silico and genome-editing approaches to prioritizing target genes. To investigate pleiotropic effects, we conducted phenome-wide association studies. Cell-type enrichment analyses were performed by integrating bulk and single-cell sequencing data. Finally, we delved into potential druggable targets for JIA. RESULTS: Fourteen genome-wide significant non-HLA loci were identified, including four novel loci, each exhibiting pleiotropic associations with other autoimmune diseases or musculoskeletal traits. We uncovered strong genetic correlation between JIA and BMD traits at 52 genomic regions, including three GWAS loci for JIA. Candidate genes with immune functions were captured by in silico analyses at each novel locus, with additional findings identified through our experimental approach. Cell-type enrichment analysis revealed 21 specific immune cell types crucial for the affected organs in JIA, indicating their potential contribution to the disease. Finally, 24 known or candidate druggable target genes were prioritized. CONCLUSIONS: Our identification of four novel JIA-associated genes, CD247, RHOH, COLEC10 and IRF8, broadens the novel potential drug repositioning opportunities. We established a new genetic link between COLEC10, TNFRSF11B and JIA/BMD. Additionally, the identification of RHOH underscores its role in positive thymocyte selection, thereby illuminating a critical facet of JIA's underlying biological mechanisms.

The Impact of Different MEFV Genotypes on Clinical Phenotype of Patients with Familial Mediterranean Fever: Special Emphasis on Joint Involvement.

Familial Mediterranean Fever (FMF) is the most common monogenic autoinflammatory disease worldwide. In this retrospective cohort study, we aimed to assess the effects of various MEFV genotypes on the clinical characteristics of the patients, with a special focus on the joint involvement. In total, 782 patients with FMF were categorized into 3 groups according to the MEFV mutation; Group 1: Patients homozygous for M694V; Group 2: Patients carrying other pathogenic MEFV variants in exon 10 in homozygous or compound heterozygous states; and Group 3: FMF patients with other variants or without mutations. Clinical and demographic findings were compared between groups. Among the 782 FMF patients, total frequency of arthritis was 237 (30.3%): 207 (26.4%) were acute monoarthritis and 67 (8.5%) were chronic arthritis. Both the frequency of arthritis (acute and/or chronic) (40.4% vs. 24.8% vs. 26.7%; p:0.001) and acute monoarthritis (35.4% vs. 20% vs. 23.7%; p:0.001) were significantly higher in Group 1 than in the other groups. FMF patients with chronic arthritis showed a distinct juvenile idiopathic arthritis (JIA) distribution pattern with a more frequent enthesitis-related arthritis (ERA) subtype (43.2%). HLA-B27 was positive in 24% of the ERA patients.Conclusion: Homozygous M694V mutation is associated with a more frequent and longer acute monoarthritis comparing to other MEFV genotypes. In addition, the risk of chronic arthritis seems not related to the MEFV mutations. However, FMF patients with chronic arthritis show a distinct ILAR JIA distribution pattern with a more frequent ERA and undifferentiated arthritis subtype. What is known: • Homozygous M694V mutation is associated with a more frequent and longer acute monoarthritis What is new: • FMF patients with chronic arthritis show a distinct ILAR JIA distribution pattern with a more frequent ERA subtype • ERA patients with negative HLA-B27 antigen should also be assessed for polyserositis episodes of FMF, especially in countries with high FMF carrier frequency.

Genetics of Macrophage Activation Syndrome in Systemic Juvenile Idiopathic Arthritis.

Macrophage activation syndrome (MAS) is a life-threatening episode of hyperinflammation driven by excessive activation and expansion of T cells (mainly CD8) and hemophagocytic macrophages producing proinflammatory cytokines. MAS has been reported in association with almost every rheumatic disease, but it is by far most common in systemic juvenile idiopathic arthritis (SJIA). Clinically, MAS is similar to familial or primary hemophagocytic lymphohistiocytosis (pHLH), a group of rare autosomal recessive disorders linked to various genetic defects all affecting the perforin-mediated cytolytic pathway employed by NK cells and cytotoxic CD8 T lymphocytes. Decreased cytolytic activity in pHLH patients leads to prolonged survival of target cells associated with increased production of proinflammatory cytokines that overstimulate macrophages. The resulting cytokine storm is believed to be responsible for the frequently fatal multiorgan system failure seen in MAS. Whole exome sequencing as well as targeted sequencing of pHLH-associated genes in patients with SJIA-associated MAS demonstrated increased "burden" of rare protein-altering variants affecting the cytolytic pathway compared to healthy controls, suggesting that as in pHLH, genetic variability in the cytolytic pathway contributes to MAS predisposition. Functional studies of some of the novel variants have shown that even in a heterozygous state, their presence partially reduces cytolytic activity that may lead to increased cytokine production.

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.

DOCK8 Mutation in Patient with Juvenile Idiopathic Arthritis and Sjögren's Syndrome.

This study investigated the association between autoimmunity and immunodeficiency in pediatric patients, focusing on the case of a 15-year-old female diagnosed with juvenile idiopathic arthritis (JIA) and secondary Sjögren's syndrome. The patient presented with a variety of symptoms, including joint pain, bronchial asthma, leukopenia, and skin lesions. Genetic testing revealed a de novo mutation in the DOCK8 gene, associated with DOCK8 deficiency, a condition usually associated with immunodeficiencies. The clinical course, diagnostic pathway, and treatment history are detailed, highlighting the importance of molecular diagnostics in understanding the genetic basis of rheumatic diseases. This case highlights the need to consider innate immune errors in patients with multiple diseases or atypical symptoms of rheumatic diseases. Furthermore, the study highlights the importance of targeted treatment, including genetic counseling, to improve patient outcomes. The observed association between autoimmunity and immune deficiency reinforces the importance of molecular testing in elucidating the causes of previously idiopathic rheumatic diseases, contributing to improved patient care and quality of life.

Is There a Link between the Molecular Basis of Juvenile Idiopathic Arthritis and Autoimmune Diseases? Systematic Review.

Juvenile Idiopathic Arthritis (JIA) is currently the most common chronic rheumatic disease in children. It is known to have no single identity, but a variety of diagnoses. Under-diagnosis is a barrier to early treatment and reduced complications of the disease. Other immune-mediated diseases may coexist in the same patient, making research in this area relevant. The main objective was to analyse whether links could be established between the molecular basis of JIA and other immune-mediated diseases. Early diagnosis may benefit patients with JIA, which in most cases goes undetected, leading to under-diagnosis, which can have a negative impact on children affected by the disease as they grow up. METHODS: We performed a PRISMA systematic review focusing on immune molecules present in different autoimmune diseases. RESULTS: A total of 13 papers from different countries dealing with the molecular basis of JIA and other immune diseases were evaluated and reviewed. CONCLUSIONS: Most of the autoimmune diseases analysed responded to the same group of drugs. Unfortunately, the reason for the under-diagnosis of these diseases remains unknown, as no evidence has been found to correlate the immunomolecular basis with the under-diagnosis of these immune-mediated diseases. The lack of information in this area means that further research is needed in order to provide a sound basis for preventing the development of immune-mediated diseases, especially in children, and to improve their quality of life through early diagnosis and treatment.

Association of IL-17A and IL-10 Polymorphisms with Juvenile Idiopathic Arthritis in Finnish Children.

To analyze the role of interleukin IL-17A and IL-10 polymorphisms in susceptibility to juvenile idiopathic arthritis (JIA), 98 Finnish children and adolescents with JIA were studied. Data from the 1000 Genomes Project, consisting of 99 healthy Finns, served as the controls. The patients were analyzed for four IL-17A and three IL-10 gene-promoter polymorphisms, and the serum IL-17A, IL-17F, IL-10, and IL-6 levels were determined. The IL-17A rs8193036 variant genotypes (CT/CC) were more common among the patients than controls, especially in those with polyarthritis (OR 1.93, 95% CI 1.11-3.36; p = 0.020). IL-17A rs2275913 minor allele A was more common in patients (OR 1.45, 95% Cl 1.08-1.94; p = 0.014) and especially among patients with oligoarthritis and polyarthritis than the controls (OR 1.61, 95%CI 1.06-2.43; p = 0.024). Carriers of the IL-17A rs4711998 variant genotype (AG/AA) had higher serum IL-17A levels than those with genotype GG. However, carriers of the variant genotypes of IL-17A rs9395767 and rs4711998 appeared to have higher IL-17F levels than those carrying wildtype. IL-10 rs1800896 variant genotypes (TC/CC) were more abundant in patients than in the controls (OR 1.97, 95%CI 1.06-3.70; p = 0.042). Carriers of the IL-10 rs1800896 variant genotypes had lower serum levels of IL-17F than those with wildtype. These data provide preliminary evidence of the roles of IL-17 and IL-10 in the pathogenesis of JIA and its subtypes in the Finnish population. However, the results should be interpreted with caution, as the number of subjects included in this study was limited.

[Monogenic variants in Laccase domain-containing 1 (LACC1) as the cause of juvenile arthritis]. / Monogene Varianten in "laccase domain-containing 1" (LACC1) als Ursache einer juvenilen Arthritis.

Monogenic mutations in laccase domain-containing 1 (LACC1) are associated with clinical pictures that mimic severe courses of polyarticular or systemic juvenile idiopathic arthritis. The diseases are characterized by an early onset during the first year of life, a familial clustering and a high inflammatory activity. The courses are mostly difficult to influence and often lead to sequelae. In this article four cases from two families are presented in which the homozygous mutation p.T276fs* in LACC1 was detected. The children initially suffered from polyarticular or systemic forms of juvenile arthritis. Of the patients two are currently being treated with tocilizumab and methotrexate and one female patient without a basis treatment is currently only receiving local repeated intra-articular steroids. A fourth female patient underwent an allogeneic bone marrow transplantation due to a relapse of an acute lymphatic leukemia. Since then, no further inflammatory symptoms have occurred. The cases presented are compared with the other 50 courses published to date. In addition, recent studies investigating the influence of LACC1 mutations, particularly on macrophage function, are summarized.

Interleukin-23 pathway at the enthesis: The emerging story of enthesitis in spondyloarthropathy.

The inflammatory disorders collectively termed the seronegative spondyloarthropathies (SpA) include ankylosing spondylitis (AS), psoriatic arthritis (PsA), reactive arthritis, the arthritis associated with inflammatory bowel disease including Crohn's disease and ulcerative colitis, the arthritis related to anterior uveitis, and finally, somewhat controversially Behcet's disease. All of these diseases are associated with SNPs in the IL-23R or the interleukin-23 (IL-23) cytokine itself and related downstream signaling JAK pathway genes and the interleukin-17 (IL-17) pathway. In rheumatoid arthritis, the target of the immune response is the synovium but the SpA disorders target the tendon, ligament, and joint capsule skeletal anchorage points that are termed entheses. The discovery that IL-23R-expressing cells were ensconced in healthy murine enthesis, and other extraskeletal anchorage points including the aortic root and the ciliary body of the eye and that systemic overexpression of IL-23 resulted in a severe experimental SpA, confirmed a fundamentally different immunobiology to rheumatoid arthritis. Recently, IL-23R-expressing myeloid cells and various innate and adaptive T cells that produce IL-17 family cytokines have also been described in the human enthesis. Blockade of IL-23 pathway with either anti-p40 or anti-p19 subunits has resulted in some spectacular therapeutic successes in psoriasis and PsA including improvement in enthesitis in the peripheral skeleton but has failed to demonstrate efficacy in AS that is largely a spinal polyenthesitis. Herein, we discuss the known biology of IL-23 at the human enthesis and highlight the remarkable emerging story of this unique skeletal tissue.

Juvenile idiopathic arthritis-associated genetic loci exhibit spatially constrained gene regulatory effects across multiple tissues and immune cell types.

Juvenile idiopathic arthritis (JIA) is an autoimmune, inflammatory joint disease with complex genetic etiology. Previous GWAS have found many genetic loci associated with JIA. However, the biological mechanism behind JIA remains unknown mainly because most risk loci are located in non-coding genetic regions. Interestingly, increasing evidence has found that regulatory elements in the non-coding regions can regulate the expression of distant target genes through spatial (physical) interactions. Here, we used information on the 3D genome organization (Hi-C data) to identify target genes that physically interact with SNPs within JIA risk loci. Subsequent analysis of these SNP-gene pairs using data from tissue and immune cell type-specific expression quantitative trait loci (eQTL) databases allowed the identification of risk loci that regulate the expression of their target genes. In total, we identified 59 JIA-risk loci that regulate the expression of 210 target genes across diverse tissues and immune cell types. Functional annotation of spatial eQTLs within JIA risk loci identified significant overlap with gene regulatory elements (i.e., enhancers and transcription factor binding sites). We found target genes involved in immune-related pathways such as antigen processing and presentation (e.g., ERAP2, HLA class I and II), the release of pro-inflammatory cytokines (e.g., LTBR, TYK2), proliferation and differentiation of specific immune cell types (e.g., AURKA in Th17 cells), and genes involved in physiological mechanisms related to pathological joint inflammation (e.g., LRG1 in arteries). Notably, many of the tissues where JIA-risk loci act as spatial eQTLs are not classically considered central to JIA pathology. Overall, our findings highlight the potential tissue and immune cell type-specific regulatory changes contributing to JIA pathogenesis. Future integration of our data with clinical studies can contribute to the development of improved JIA therapy.

Association between Interleukin-17F 7488A/G and 7383A/G polymorphisms and susceptibility to juvenile idiopathic arthritis.

BACKGROUND: Interleukin-17F (IL-17F), one of the cytokines, is crucial in the pathophysiology of juvenile idiopathic arthritis (JIA). Therefore, we aimed to determine the relation between IL17F 7488A/G and IL17F 7383A/G single-nucleotide polymorphisms and JIA susceptibility and to explain their impact on the disease activity. METHODS: Genomic DNA of 70 patients with JIA and 70 age and sex-matched controls were extracted and typed for IL17F 7488A/G and IL17F 7383A/G single-nucleotide polymorphisms, using polymerase chain reaction with sequence-specific primers method, and compared between patients and controls. RESULTS: When compared to AA participants, children with the AG genotype of the IL17F 7488A/G and IL17F 7383A/G polymorphisms showed a substantially greater risk of JIA. Furthermore, children with the G allele were 2.8 folds more likely to have JIA than the A allele for IL17F 7488A/G polymorphism and 3.72 folds for IL17F 7383A/G polymorphism. Children with AG genotype of IL17F 7383A/G polymorphism were far more likely to have high activity JIA. CONCLUSIONS: The G allele of both IL17F 7488A/G and IL17F7383 A/G polymorphisms is associated with increased JIA susceptibility, and JIA at High Disease Activity was more likely to develop in AG subjects of the IL17F 7383 A/G polymorphism. IMPACT: The relationship between Interleukin-17F 7488A/G and 7383A/G polymorphisms and risk for JIA has not been recognized before. Impact of Interleukin-17F 7488A/G and 7383A/G genotypes on JIA disease activity. The G allele of both IL17F 7488A/G and IL17F7383 A/G polymorphisms are associated with increased JIA susceptibility. AG genotype of Interleukin-17F 7383 A/G polymorphism compared to AA patients, had a higher probability of developing JIA at a High Disease Activity (HDA) level.

Genetic Background and Molecular Mechanisms of Juvenile Idiopathic Arthritis.

Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in the paediatric population. JIA comprises a heterogeneous group of disorders with different onset patterns and clinical presentations with the only element in common being chronic joint inflammation. This review sought to evaluate the most relevant and up-to-date evidence on current knowledge regarding the pathogenesis of JIA subtypes to provide a better understanding of these disorders. Despite significant improvements over the past decade, the aetiology and molecular mechanisms of JIA remain unclear. It has been suggested that the immunopathogenesis is characterised by complex interactions between genetic background and environmental factors that may differ between JIA subtypes. Human leukocyte antigen (HLA) haplotypes and non-HLA genes play a crucial role in the abnormal activation of both innate and adaptive immune cells that cooperate in causing the inflammatory process. This results in the involvement of proinflammatory cytokines, including tumour necrosis factor (TNF)α, interleukin (IL)-1, IL-6, IL-10, IL-17, IL-21, IL-23, and others. These mediators, interacting with the surrounding tissue, cause cartilage stress and bone damage, including irreversible erosions. The purpose of this review is to provide a comprehensive overview of the genetic background and molecular mechanisms of JIA.

Experience of using genetically engineered biological drugs in children with a systemic form of JIA in the Karaganda region.

Despite all the achievements of science and medicine, juvenile idiopathic arthritis today remains one of the main childhood diseases that lead to severe irreversible consequences. This, in turn, makes it urgent to search for effective drugs for the treatment of juvenile idiopathic arthritis, of which interleukin 1 (anakinra) and interleukin 6 (tocilizumab) inhibitors are becoming increasingly popular. AIM: to analyse the efficacy of genetically engineered biological drugs, namely anakinra and tocilizumab in children with systemic juvenile idiopathic arthritis among patients of the Karaganda region. The study involved 176 patients aged 4-17 years with a diagnosis of systemic juvenile idiopathic arthritis and with resistance to methotrexate for 3 months. Among all patients, 64 children received injections of anakinra, and 63 received tocilizumab in standard doses. The control group consisted of 50 patients of the same age category. Assessment of the efficacy of treatment was conducted at 2, 4, 8, 16, 24, and 48 weeks using ACR Pediatric criteria. The clinical effect of both drugs was detected as early as the second week after the start of therapy. At week 12 of the study in the tocilizumab group, the efficacy of treatment for ACR Pediatric 30, 50, and 70 reached 82 %, 71 %, and 69 %, and in the anakinra group - 89 %, 81 %, and 80 % respectively, while in the control group ACR Pediatric 30 after 12 weeks of treatment was achieved in 21 % of patients, ACR Pediatric 50 - in 12 %, and ACR Pediatric 70 - in 9 % (p Keywords: systemic arthritis, polyarthritis, tocilizumab, anakinra, genetically engineered biological drugs.

Causal association of juvenile idiopathic arthritis-associated uveitis with depression and anxiety: a bidirectional Mendelian randomization study.

PURPOSE: The objective of this article was to examine the potential effect of juvenile idiopathic arthritis-associated uveitis (JIAU) on the risk of major depressive and anxiety disorders through Mendelian randomization (MR) study. METHODS: Genetic instrumental variables from the largest available genome-wide association study for JIAU, major depressive disorder, and anxiety disorder were applied. A set of complementary MR approaches including inverse-variance weighted (IVW) were carried out to verify the estimate association and assess horizontal pleiotropy. RESULTS: Our results indicated that genetically driven JIAU did not causally produce changes in major depressive or anxiety disorders (IVW: OR = 1.001, 95% CI = 0.997-1.006, P = 0.581; IVW: OR = 1.006, 95% CI = 0.980-1.033, P = 0.649, respectively). In addition, the risk of JIAU could not be influenced by genetically predicted major depressive or anxiety disorders (IVW: OR = 1.132, 95% CI = 0.914-1.404, P = 0.256; IVW: OR = 1.019, 95% CI = 0.548-1.896, P = 0.953, respectively). Besides, several sensitivity analyses indicated that our MR results were robust and no horizontal pleiotropy was observed (P > 0.05). CONCLUSIONS: Our MR study does not reveal sufficient evidence to support the causal association of JIAU with the development of major depressive or anxiety disorders in both directions. Further large studies are warranted to validate the undetermined relationship between JIAU and the risk of major depressive or anxiety disorders.

Antigen-driven PD-1+ TOX+ BHLHE40+ and PD-1+ TOX+ EOMES+ T lymphocytes regulate juvenile idiopathic arthritis in situ.

T lymphocytes accumulate in inflamed tissues of patients with chronic inflammatory diseases (CIDs) and express pro-inflammatory cytokines upon re-stimulation in vitro. Further, a significant genetic linkage to MHC genes suggests that T lymphocytes play an important role in the pathogenesis of CIDs including juvenile idiopathic arthritis (JIA). However, the functions of T lymphocytes in established disease remain elusive. Here we dissect the transcriptional and the clonal heterogeneity of synovial T lymphocytes in JIA patients by single-cell RNA sequencing combined with T cell receptor profiling on the same cells. We identify clonally expanded subpopulations of T lymphocytes expressing genes reflecting recent activation by antigen in situ. A PD-1+ TOX+ EOMES+ population of CD4+ T lymphocytes expressed immune regulatory genes and chemoattractant genes for myeloid cells. A PD-1+ TOX+ BHLHE40+ population of CD4+ , and a mirror population of CD8+ T lymphocytes expressed genes driving inflammation, and genes supporting B lymphocyte activation in situ. This analysis points out that multiple types of T lymphocytes have to be targeted for therapeutic regeneration of tolerance in arthritis.

AGER gene variant as a risk factor for juvenile idiopathic arthritis.

BACKGROUND: The AGER gene encodes a cell surface multiligand receptor of advanced glycation end-products that is also capable of binding other molecules and is involved in numerous pathways related to inflammation, apoptosis, immunity and so on. In the present study, we aimed to investigate whether the AGER rs1035798 (G>A) intronic polymorphism, showing an association with multiple sclerosis and rheumatoid arthritis in adults, is related to juvenile idiopathic arthritis (JIA). METHODS: Caucasian children from the Belarusian population were enrolled in the study. In total, there were 201 cases with JIA, 37 with juvenile systemic lupus erythematosus, 222 children with the articular syndrome of non-autoimmune etiology (positive control for JIA) and 365 negative controls (children without any autoimmune or inflammatory diseases). Genomic DNA samples from the patients and controls were genotyped by a real-time polymerase chain reaction. RESULTS: A marked association of the homozygous AA rs1035798 genotype with JIA (p = 5 × 10-4 ) was found. Allele A was also associated with JIA (p = 0.0058), as well as with the articular syndrome of non-autoimmune etiology (p = 0.0264). The highest frequencies of the AA genotype were found in the subgroups of JIA patients with polyarthritis or severe oligoarthritis. The AA genotype patients also had the smallest mean age of the JIA onset. CONCLUSIONS: Our results demonstrate that the AGER rs1035798 AA genotype is a risk factor for JIA in Belarusian children. They also suggest a link between the AGER AA genotype and the risk of JIA early onset and severity. However, the functional relevance of the rs1035798 polymorphism is still unclear.

Adult-onset Still's disease or systemic-onset juvenile idiopathic arthritis and spondyloarthritis: overlapping syndrome or phenotype shift?

OBJECTIVES: Systemic-onset JIA (SJIA) and adult-onset Still's disease (AOSD) are the same sporadic systemic auto-inflammatory disease. SpA is a group of inflammatory non-autoimmune disorders. We report the observations of eight patients with SJIA/AOSD who also presented features of SpA during their disease evolution and estimate the prevalence of SpA in SJIA/AOSD. METHODS: This was a retrospective national survey of departments of paediatric and adult rheumatology and internal medicine. To be included, SJIA patients had to fulfil the ILAR criteria, AOSD patients the Yamaguchi or Fautrel criteria, and all patients the Assessment of SpondyloArthritis International Society (ASAS) classification criteria for axial or peripheral SpA, ESSG criteria for SpA or Classification Criteria for Psoriatic Arthritis (CASPAR) criteria for PsA. The data were collected with a standardized form. RESULTS: Eight patients (five adults) were identified in one paediatric and two adult departments. In all but one patient, SpA manifestations occurred several years after SJIA/AOSD onset [mean (s.d.) delay 6.2 (3.8) years]. Two patients had peripheral and three axial SpA, and four later exhibited PsA and one SAPHO syndrome. The prevalence of SpA in an adult cohort of 76 patients with AOSD was 6.58% (95% CI 2.17, 14.69), greater than the prevalence of SpA in the French general population (0.3%; 95% CI 0.17, 0.46). The prevalence of SpA in an SJIA cohort of 30 patients was 10% (95% CI 2.11, 26.53), more than that reported in the general population of industrialized countries, estimated at 0.016-0.15%. CONCLUSION: While the temporal disassociation between SpA and AOSD in most cases might suggest a coincidental finding, our work raises the possibility of an SpA/AOSD spectrum overlap that needs further study.