Pyruvate metabolism controls chromatin remodeling during CD4+ T cell activation.

Upon antigen-specific T cell receptor (TCR) engagement, human CD4+ T cells proliferate and differentiate, a process associated with rapid transcriptional changes and metabolic reprogramming. Here, we show that the generation of extramitochondrial pyruvate is an important step for acetyl-CoA production and subsequent H3K27ac-mediated remodeling of histone acetylation. Histone modification, transcriptomic, and carbon tracing analyses of pyruvate dehydrogenase (PDH)-deficient T cells show PDH-dependent acetyl-CoA generation as a rate-limiting step during T activation. Furthermore, T cell activation results in the nuclear translocation of PDH and its association with both the p300 acetyltransferase and histone H3K27ac. These data support the tight integration of metabolic and histone-modifying enzymes, allowing metabolic reprogramming to fuel CD4+ T cell activation. Targeting this pathway may provide a therapeutic approach to specifically regulate antigen-driven T cell activation.

Perspectives of Pediatric Rheumatologists on Initiating and Tapering Biologics in Patients with Juvenile Idiopathic Arthritis: A Formative Qualitative Study.

BACKGROUND: Few studies have examined pediatric rheumatologists' approaches to treatment decision making for biologic therapy for patients with juvenile idiopathic arthritis (JIA). This study presents the qualitative research undertaken to support the development of a Best-Worst Scaling (BWS) survey for tapering in JIA. The study objectives were to (1) describe the treatment decision-making process of pediatric rheumatologists to initiate and taper biologics; and (2) select attributes for a BWS survey. METHODS: Pediatric rheumatologists across Canada were recruited to participate in interviews using purposeful sampling. Interviews were conducted until saturation was achieved. Interview recordings were transcribed verbatim and transcripts were analyzed using deductive thematic analysis. Initial codes were organized into themes and subthemes using an iterative process. Attributes for the BWS survey were developed from these themes and a literature review was conducted in parallel to inform survey development. Further refinement of the attributes was done through consultation with the research team. RESULTS: Five pediatric rheumatologists participated in the interviews. Shared decision making was part of the approach to initiating and tapering biologics in their practice. Tapering approaches differed; some pediatric rheumatologists preferred to stop biologics immediately, while others tapered by reducing dose and/or increasing the dose interval over time. A total of 14 attributes were developed for the BWS. Thirteen attributes were selected from the themes that emerged from the qualitative interviews and one attribute was included after review with the research team. Attributes related to patient characteristics included JIA subtype, time in remission, history or presence of joint damage or erosive disease, how challenging it was to achieve remission, and history of flares. Contextual attributes included accessibility of biologics and willingness to taper biologics. CONCLUSION: This study contributes to the limited literature on pediatric rheumatologists' approaches to treatment decision making for biologics in JIA and identifies attributes that affect the decision to both initiate and taper. Further research is planned to implement the BWS survey to understand the importance of the attributes identified. Additional investigation is required to determine if these characteristics align with patient and parent preferences.

The European network for care of children with paediatric rheumatic diseases: care across borders.

OBJECTIVES: To provide an overview of the paediatric rheumatology (PR) services in Europe, describe current delivery of care and training, set standards for care, identify unmet needs and inform future specialist service provision. METHODS: An online survey was developed and presented to national coordinating centres of the Paediatric Rheumatology International Trials Organisation (PRINTO) (country survey) and to individual PR centres (centre and disease surveys) as a part of the European Union (EU) Single Hub and Access point for paediatric Rheumatology in Europe project. The survey contained components covering the organization of PR care, composition of teams, education, health care and research facilities and assessment of needs. RESULTS: Response rates were 29/35 (83%) for country surveys and 164/288 (57%) for centre surveys. Across the EU, approximately one paediatric rheumatologist is available per million population. In all EU member states there is good access to specialist care and medications, although biologic drug availability is worse in Eastern European countries. PR education is widely available for physicians but is insufficient for allied health professionals. The ability to participate in clinical trials is generally high. Important gaps were identified, including lack of standardized clinical guidelines/recommendations and insufficient adolescent transition management planning. CONCLUSION: This study provides a comprehensive description of current specialist PR service provision across Europe and did not reveal any major differences between EU member states. Rarity, chronicity and complexity of diseases are major challenges to PR care. Future work should facilitate the development, dissemination and implementation of standards of care, treatment and service recommendations to further improve patient-centred health care across Europe.

PD-1+CD8+ T cells are clonally expanding effectors in human chronic inflammation.

Chronic inflammatory diseases are characterized by recurrent inflammatory attacks in the tissues mediated by autoreactive T cells. Identity and functional programming of CD8+ T cells at the target site of inflammation still remain elusive. One key question is whether, in these antigen-rich environments, chronic stimulation leads to CD8+ T cell exhaustion comparable to what is observed in infectious disease contexts. In the synovial fluid (SF) of juvenile idiopathic arthritis (JIA) patients, a model of chronic inflammation, an overrepresentation of PD-1+CD8+ T cells was found. Gene expression profiling, gene set enrichment analysis, functional studies, and extracellular flux analysis identified PD-1+CD8+ T cells as metabolically active effectors, with no sign of exhaustion. Furthermore, PD-1+CD8+ T cells were enriched for a tissue-resident memory (Trm) cell transcriptional profile and demonstrated increased clonal expansion compared with the PD-1- counterpart, suggesting antigen-driven expansion of locally adapted cells. Interestingly, this subset was also found increased in target tissues in other human chronic inflammatory diseases. These data indicate that local chronic inflammation drives the induction and expansion of CD8+ T cells endowed with potential detrimental properties. Together, these findings lay the basis for investigation of PD-1-expressing CD8+ T cell targeting strategies in human chronic inflammatory diseases.

Consensus-based recommendations for the management of uveitis associated with juvenile idiopathic arthritis: the SHARE initiative.

BACKGROUND: In 2012, a European initiative called Single Hub and Access point for pediatric Rheumatology in Europe (SHARE) was launched to optimise and disseminate diagnostic and management regimens in Europe for children and young adults with rheumatic diseases. Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in children and uveitis is possibly its most devastating extra-articular manifestation. Evidence-based guidelines are sparse and management is mostly based on physicians' experience. Consequently, treatment practices differ widely, within and between nations. OBJECTIVES: To provide recommendations for the diagnosis and treatment of JIA-associated uveitis. METHODS: Recommendations were developed by an evidence-informed consensus process using the European League Against Rheumatism standard operating procedures. A committee was constituted, consisting of nine experienced paediatric rheumatologists and three experts in ophthalmology from Europe. Recommendations derived from a validated systematic literature review were evaluated by an Expert Committee and subsequently discussed at two consensus meetings using nominal group techniques. Recommendations were accepted if >80% agreement was reached (including all three ophthalmologists). RESULTS: In total, 22 recommendations were accepted (with >80% agreement among experts): 3 on diagnosis, 5 on disease activity measurements, 12 on treatment and 2 on future recommendations. CONCLUSIONS: The SHARE initiative aims to identify best practices for treatment of patients suffering from JIA-associated uveitis. Within this remit, recommendations for the diagnosis and treatment of JIA-associated uveitis have been formulated by an evidence-informed consensus process to suggest a standard of care for JIA-associated uveitis patients throughout Europe.

Self-Sustained Resistance to Suppression of CD8+ Teff Cells at the Site of Autoimmune Inflammation Can Be Reversed by Tumor Necrosis Factor and Interferon-γ Blockade.

OBJECTIVE: Resistance of Teff cells to Treg cell-mediated suppression contributes to the breakdown of peripheral tolerance in the inflamed joints of patients with juvenile idiopathic arthritis (JIA). However, unanswered questions are whether this resistant phenotype is self-sustained and whether CD8+ and CD4+ Teff cells share the same mechanism of resistance to suppression. We undertook this study to investigate intrinsic resistance of CD8+ Teff cells to suppression and to determine how this can be targeted therapeutically. METHODS: CD8+ or CD4+ Teff cells were cultured with or without antigen-presenting cells (APCs) in Treg cell-dependent and -independent suppression assays. Synovial fluid (SF)-derived Teff cells were crosscultured with peripheral blood (PB) Treg cells from JIA patients or healthy controls. Tumor necrosis factor (TNF) or interferon-γ (IFNγ) blocking agents were used to restore Teff cell responsiveness to suppression. RESULTS: Suppression of cell proliferation and cytokine production in CD8+ Teff cells from the SF of JIA patients was severely impaired compared to that in CD8+ Teff cells from the PB of JIA patients, regardless of the presence of APCs and CD4+ Teff cells. Similar to CD4+ Teff cells, impaired suppression of CD8+ Teff cells was shown to be an intrinsic feature of this cell population. While TNF blockade restored both CD8+ and CD4+ Teff cell susceptibility to suppression, autocrine release of IFNγ selectively sustained CD8+ Teff cell resistance, which could be relieved by IFNγ blockade. CONCLUSION: Unlike CD4+ Teff cells, resistance of CD8+ Teff cells to suppression at the site of autoimmune inflammation is maintained by autocrine release of IFNγ, and blockade of IFNγ restores CD8+ Teff cell responsiveness to suppression. These findings indicate a potential therapeutic value of blocking IFNγ to restore immune regulation in JIA.