CD161(+) Tconv and CD161(+) Treg Share a Transcriptional and Functional Phenotype despite Limited Overlap in TCR beta Repertoire

Human regulatory T cells (Treg) are important in immune regulation, but can also show plasticity in specific settings. CD161 is a lectin-like receptor and its expression identifies an effector-like Treg population. Here, we determined how CD161+ Treg relate to CD161+ conventional T cells (Tconv). Transcriptional profiling identified a shared transcriptional signature between CD161+ Tconv and CD161+ Treg, which is associated with T helper (Th)1 and Th17 cells, and tissue homing, including high expression of gut-homing receptors. Upon retinoic acid (RA) exposure, CD161+ T cells were more enriched for CCR9+ and integrin α4+β7+ cells than CD161− T cells. In addition, CD161+ Tconv and CD161+ Treg were enriched at the inflamed site in autoimmune arthritis, and both CD161+ and CD161− Treg from the inflamed site were suppressive in vitro. CD161+ T cells from the site of autoimmune arthritis showed a diminished gut-homing phenotype and blunted response to RA suggesting prior imprinting by RA in the gut or at peripheral sites rather than during synovial inflammation. TCRβ repertoires of CD161+ and CD161− Tconv and Treg from blood showed limited overlap whereas there was clear overlap between CD161+ and CD161− Tconv, and CD161+ and CD161− Treg from the inflamed site suggesting that the inflamed environment may alter CD161 levels, potentially contributing to disease pathogenesis

Current developments in the use of biomarkers for juvenile idiopathic arthritis

Use of biomarkers in clinical practice has proved extremely valuable and is a rapidly expanding field. However, despite the huge potential of biomarkers, for juvenile idiopathic arthritis (JIA) there are currently no validated paediatric biomarkers available to help with setting up a more tailored approach on which drug choice could be based, to achieve remission early in the course of disease. Early remission reduces burden of disease, limits side effects from toxic and unnecessary medication, and, most importantly, enhances quality of life. Several studies have suggested promising biomarkers: these may be a protein, cellular component, mRNA, or genetic component, for example a single nucleotide polymorphism (SNP). Here we describe recent developments in the use of biomarkers for JIA and their potential to assist in management of disease by predicting disease phenotype, severity, progression, and response to treatment, and determining when patients have reached stable remission and can safely discontinue treatment

Brief Report: Innate lymphoid cells and T-cells contribute to the IL-17A signature detected in the synovial fluid of patients with Juvenile Idiopathic Arthritis

OBJECTIVE: Evidence suggests that aberrant function of innate lymphoid cells (ILC), whose functional and transcriptional profile overlap with T helper (Th) cell subsets, contribute to immune-mediated pathologies. To date, analysis of Juvenile Idiopathic Arthritis (JIA) immune-pathology has concentrated on the contribution of CD4+ T-cells; we have previously identified an expansion of Th17 cells within the synovial fluid (SF) of JIA patients. Here, we extend this analysis to investigate a role for ILC and other IL-17 producing T-cell subsets. METHODS: ILC and CD3+ T-cell subsets were defined in peripheral blood mononuclear cells (PBMC) (healthy adult, healthy child and JIA patients) and JIA SF mononuclear cells (SFMC) using flow cytometry. Defined subsets in SFMC were correlated with clinical measures including physician's visual analogue scale (VAS), active joint count and erythrocyte sedimentation rate (ESR). Transcription factor and cytokine profiles of sorted ILC were assessed by qPCR. RESULTS: Group 1 ILC (ILC1), NKp44-group 3 ILC (NCR-ILC3) and NKp44+group 3 ILC (NCR+ILC3) were enriched in the JIA-SFMC compared to PBMC, which corresponded with an increase in transcripts for TBX21, IFNG and IL17A. Of the ILC subsets, NCR-ILC3 frequency in JIA-SFMC displayed the strongest positive association with clinical measures which was mirrored by an expansion in IL-17A+CD4+, IL-17A+CD8+ and IL-17A+γδ T-cells. CONCLUSION: We demonstrate that the strength of the IL-17A signature in JIA-SFMC is determined by multiple lymphoid cell-types, including NCR-ILC3, IL-17A+CD4+, IL-17A+CD8+ and IL-17A+γδ T-cells. These observations may have important implications for the development of stratified therapeutics. This article is protected by copyright. All rights reserved

CD19+CD24hiCD38hi B Cells Are Expanded in Juvenile Dermatomyositis and Exhibit a Pro-Inflammatory Phenotype After Activation Through Toll-Like Receptor 7 and Interferon-α

Juvenile dermatomyositis (JDM) is a rare form of childhood autoimmune myositis that presents with proximal muscle weakness and skin rash. B cells are strongly implicated in the pathogenesis of the disease, but the underlying mechanisms are unknown. Therefore, the main objective of our study was to investigate mechanisms driving B cell lymphocytosis and define pathological features of B cells in JDM patients. Patients were recruited through the UK JDM Cohort and Biomarker study. Peripheral blood B cell subpopulations were immunophenotyped by flow cytometry. The results identified that immature transitional B cells were significantly expanded in active JDM, actively dividing, and correlated positively with disease activity. Protein and RNAseq analysis revealed high interferon alpha (IFNa) and TLR7-pathway signatures pre-treatment. Stimulation of B cells through TLR7/8 promoted both IL-10 and IL-6 production in controls but failed to induce IL-10 in JDM patient cells. Interrogation of the CD40-CD40L pathway (known to induce B cell IL-10 and IL-6) revealed similar expression of IL-10 and IL-6 in B cells cultured with CD40L from both JDM patients and controls. In conclusion, JDM patients with active disease have a significantly expanded immature transitional B cell population which correlated with the type I IFN signature. Activation through TLR7 and IFNa may drive the expansion of immature transitional B cells in JDM and skew the cells toward a pro-inflammatory phenotype

CD161+ T cells in Immune Regulation

Immune regulation is an important process in the human body to maintain immune homeostasis. Regulatory T cells (Treg) are important in this process, however, under specific conditions, Treg can produce pro-inflammatory cytokines. These cytokine-producing Treg are identified by expression of CD161, a C-type lectin receptor expressed by Th17 cells. Both CD161+ Treg and CD161+ conventional T cells (Tconv) are enriched at the inflamed site in childhood arthritis indicating that these cells might be involved in disease pathogenesis. Therefore, the aim of this thesis is to understand the role of CD161+ T cells in immune regulation. Analysis of transcriptional and protein signatures of CD161+ Treg compared to CD161- Treg, and CD161+ Tconv compared to CD161- Tconv from blood of healthy adults identified a shared signature between CD161+ Treg and CD161+ Tconv. CD161+ Treg express similar or higher levels of markers associated with a Treg phenotype. In addition, both CD161+ Tconv and CD161+ Treg express high levels of markers associated with Th1 and Th17 cells, and tissue homing including receptors for gut homing, which are upregulated in response to retinoic acid. Despite the shared signatures of CD161+ Tconv and CD161+ Treg, their TCRβ repertoire is largely non-overlapping. CD161+ Tconv and CD161+ Treg from synovial fluid (SF) also produce pro-inflammatory cytokines, express markers associated with Th1 and Th17 cells, and are suppressive in an in vitro suppression assay. Expression of gut homing receptors by CD161+ T cells was lower in SF compared to blood. Analysis of TCRβ repertoire of CD161+ and CD161- Tconv, and CD161+ and CD161- Treg from SF revealed overlap between CD161+ and CD161- T cell populations, and CD161+ Tconv and CD161+ Treg. The data presented in this thesis highlights a potential role for CD161+ T cells in disease pathogenesis and suggest that CD161 expression is regulated differently in health and disease

Enhancing translational research in paediatric rheumatology through standardization.

The past decade has seen many successes in translational rheumatology, from dramatic improvements in outcomes brought about by novel biologic therapies, to the discovery of new monogenic inflammatory disorders. Advances in molecular medicine, combined with progress towards precision care, provide an excellent opportunity to accelerate the translation of biological understanding to the bedside. However, although the field of rheumatology is a leader in the standardization of data collection and measures of disease activity, it lags behind in standardization of biological sample collection and assay performance. Uniform approaches are necessary for robust collaborative research, particularly in rare diseases. Standardization is also critical to increase reproducibility between centres, a prerequisite for clinical implementation of translational research. This Perspectives article emphasizes the need for standardization and implementation of best practices, presented in the context of lessons learned from international biorepository networks

Advances in biomarkers for paediatric rheumatic diseases

The search for biomarkers in paediatric rheumatic diseases, particularly juvenile idiopathic arthritis (JIA), childhood lupus nephritis (LN), and juvenile idiopathic inflammatory myopathies (JIIMs) is attracting increased interest. In JIA, a number of biomarkers have shown potential for predicting clinical phenotype, disease activity and severity, clinical remission and relapse, response to treatment, and disease course over time. In systemic JIA, measurement of biomarkers that reflect the degree of activation and expansion of T cells and macrophages might be helpful for detecting subclinical macrophage activation syndrome. Urine biomarkers for childhood LN hold promise for facilitating early diagnosis and improving disease monitoring and assessment of response to therapy. Myositis-specific autoantibodies define distinct serological subgroups of JIIMs, albeit with similar clinical features, responses to therapy, and prognoses. Use of biomarkers may potentially help to avoid invasive procedures, such as renal biopsy in systemic lupus erythematosus and muscle biopsy in juvenile dermatomyositis. Incorporation of effective and reliable biomarkers into routine practice might facilitate adoption of a stratified approach to investigation and management, foster the implementation of research into the design of personalized and targeted therapies, and ultimately lead to more rational and effective clinical care