Natural killer (NK) and CD1d-restricted Valpha14i natural killer T (NKT) cells play a critical early role in host defense. Here we show that mice with a targeted deletion of T-bet, a T-box transcription factor required for Th1 cell differentiation, have a profound, stem cell-intrinsic defect in their ability to generate mature NK and Valpha14i NKT cells. Both cell types fail to complete normal terminal maturation and are present in decreased numbers in peripheral lymphoid organs of T-bet(-/-) mice. T-bet expression is regulated during NK cell differentiation by NK-activating receptors and cytokines known to control NK development and effector function. Our results identify T-bet as a key factor in the terminal maturation and peripheral homeostasis of NK and Valpha14i NKT cells.

We have generated mice with a deficiency in T1/ST2 expression to clarify the roles of T1/ST2 in T helper cell type 2 (Th2) responses. Using immunological challenges normally characterized by a Th2-like response, we have compared the responses of T1/ST2-deficient mice with those generated by wild-type mice. Using a primary pulmonary granuloma model, induced with Schistosoma mansoni eggs, we demonstrate that granuloma formation, characterized by eosinophil infiltration, is abrogated in T1/ST2-deficient mice. Furthermore, we clearly demonstrate that in the absence of T1/ST2 expression, the levels of Th2 cytokine production are severely impaired after immunization. Thus, in a secondary pulmonary granuloma model, draining lymph node cells from the T1/ST2-deficient animals produced significantly reduced levels of IL-4 and IL-5, despite developing granulomas of a magnitude similar to those of wild-type mice and comparable antigen-specific immunoglobulin isotype production. These data clearly demonstrate that T1/ST2 expression plays a role in the development of Th2-like cytokine responses and indicate that effector functions are inhibited in its absence.

IntroductionRheumatoid arthritis (RA) is a complex and clinically heterogeneous autoimmune disease. Currently, the relationship between pathogenic molecular drivers of disease in RA and therapeutic response is poorly understood.MethodsWe analyzed synovial tissue samples from two RA cohorts of 49 and 20 patients using a combination of global gene expression, histologic and cellular analyses, and analysis of gene expression data from two further publicly available RA cohorts. To identify candidate serum biomarkers that correspond to differential synovial biology and clinical response to targeted therapies, we performed pre-treatment biomarker analysis compared with therapeutic outcome at week 24 in serum samples from 198 patients from the ADACTA (ADalimumab ACTemrA) phase 4 trial of tocilizumab (anti-IL-6R) monotherapy versus adalimumab (anti-TNFα) monotherapy.ResultsWe documented evidence for four major phenotypes of RA synovium – lymphoid, myeloid, low inflammatory, and fibroid - each with distinct underlying gene expression signatures. We observed that baseline synovial myeloid, but not lymphoid, gene signature expression was higher in patients with good compared with poor European league against rheumatism (EULAR) clinical response to anti-TNFα therapy at week 16 (P =0.011). We observed that high baseline serum soluble intercellular adhesion molecule 1 (sICAM1), associated with the myeloid phenotype, and high serum C-X-C motif chemokine 13 (CXCL13), associated with the lymphoid phenotype, had differential relationships with clinical response to anti-TNFα compared with anti-IL6R treatment. sICAM1-high/CXCL13-low patients showed the highest week 24 American College of Rheumatology (ACR) 50 response rate to anti-TNFα treatment as compared with sICAM1-low/CXCL13-high patients (42% versus 13%, respectively, P =0.05) while anti-IL-6R patients showed the opposite relationship with these biomarker subgroups (ACR50 20% versus 69%, P =0.004).ConclusionsThese data demonstrate that underlying molecular and cellular heterogeneity in RA impacts clinical outcome to therapies targeting different biological pathways, with patients with the myeloid phenotype exhibiting the most robust response to anti-TNFα. These data suggest a path to identify and validate serum biomarkers that predict response to targeted therapies in rheumatoid arthritis and possibly other autoimmune diseases.Trial registrationClinicalTrials.gov NCT01119859

Summary There is a current imperative to unravel the hierarchy of molecular pathways that drive the transition of early to established disease in rheumatoid arthritis (RA). Herein, we report a comprehensive RNA sequencing analysis of the molecular pathways that drive early RA progression in the disease tissue (synovium), comparing matched peripheral blood RNA-seq in a large cohort of early treatment-naive patients, namely, the Pathobiology of Early Arthritis Cohort (PEAC). We developed a data exploration website ( https://peac.hpc.qmul.ac.uk/ ) to dissect gene signatures across synovial and blood compartments, integrated with deep phenotypic profiling. We identified transcriptional subgroups in synovium linked to three distinct pathotypes: fibroblastic pauci-immune pathotype, macrophage-rich diffuse-myeloid pathotype, and a lympho-myeloid pathotype characterized by infiltration of lymphocytes and myeloid cells. This is suggestive of divergent pathogenic pathways or activation disease states. Pro-myeloid inflammatory synovial gene signatures correlated with clinical response to initial drug therapy, whereas plasma cell genes identified a poor prognosis subgroup with progressive structural damage.

Transcription factors have a profound influence on both the differentiation and effector function of cells of the immune system. T-bet controls the cytotoxicity of CD8(+) T cells and the production of interferon-gamma, and it also affects the development and function of natural killer cells and natural killer T cells. Other factors such as eomesodermin, MEF, ETS1 and members of the interferon-regulatory factor family also contribute to the effector function of immune cells. In this review, we focus on recent studies that have shed light on the transcriptional mechanisms that regulate cellular effector function in the immune system.

Inactivation of the TNFAIP3 gene, encoding the A20 protein, is associated with critical inflammatory diseases including multiple sclerosis, rheumatoid arthritis and Crohn's disease. However, the role of A20 in attenuating inflammatory signalling is unclear owing to paradoxical in vitro and in vivo findings. Here we utilize genetically engineered mice bearing mutations in the A20 ovarian tumour (OTU)-type deubiquitinase domain or in the zinc finger-4 (ZnF4) ubiquitin-binding motif to investigate these discrepancies. We find that phosphorylation of A20 promotes cleavage of Lys63-linked polyubiquitin chains by the OTU domain and enhances ZnF4-mediated substrate ubiquitination. Additionally, levels of linear ubiquitination dictate whether A20-deficient cells die in response to tumour necrosis factor. Mechanistically, linear ubiquitin chains preserve the architecture of the TNFR1 signalling complex by blocking A20-mediated disassembly of Lys63-linked polyubiquitin scaffolds. Collectively, our studies reveal molecular mechanisms whereby A20 deubiquitinase activity and ubiquitin binding, linear ubiquitination, and cellular kinases cooperate to regulate inflammation and cell death.

ObjectivesTo unravel the hierarchy of cellular/molecular pathways in the disease tissue of early, treatment-naïve rheumatoid arthritis (RA) patients and determine their relationship with clinical phenotypes and treatment response/outcomes longitudinally.Methods144 consecutive treatment-naïve early RA patients (<12 months symptoms duration) underwent ultrasound-guided synovial biopsy before and 6 months after disease-modifying antirheumatic drug (DMARD) initiation. Synovial biopsies were analysed for cellular (immunohistology) and molecular (NanoString) characteristics and results compared with clinical and imaging outcomes. Differential gene expression analysis and logistic regression were applied to define variables correlating with treatment response and predicting radiographic progression.ResultsCellular and molecular analyses of synovial tissue demonstrated for the first time in early RA the presence of three pathology groups: (1) lympho-myeloid dominated by the presence of B cells in addition to myeloid cells; (2) diffuse-myeloid with myeloid lineage predominance but poor in B cells nd (3) pauci-immune characterised by scanty immune cells and prevalent stromal cells. Longitudinal correlation of molecular signatures demonstrated that elevation of myeloid- and lymphoid-associated gene expression strongly correlated with disease activity, acute phase reactants and DMARD response at 6 months. Furthermore, elevation of synovial lymphoid-associated genes correlated with autoantibody positivity and elevation of osteoclast-targeting genes predicting radiographic joint damage progression at 12 months. Patients with predominant pauci-immune pathology showed less severe disease activity and radiographic progression.ConclusionsWe demonstrate at disease presentation, prior to pathology modulation by therapy, the presence of specific cellular/molecular synovial signatures that delineate disease severity/progression and therapeutic response and may pave the way to more precise definition of RA taxonomy, therapeutic targeting and improved outcomes.

Functional redundancy is highly prevalent among the Th2 interleukins (IL)-4, IL-5, IL-9, and IL-13. To define the critical functions of these cytokines, we have generated a novel panel of compound Th2 cytokine-deficient mice (from single to quadruple cytokine knockouts). We find that these Th2 cytokines are not essential for fetal survival even during allogeneic pregnancy. Using intestinal parasite infection and a pulmonary granuloma model, we demonstrate cryptic roles for IL-4, IL-5, IL-9, and IL-13 in these responses. Significantly, although IL-5, IL-9, and IL-13 add to the speed and magnitude of the response, a threshold is reached at which IL-4 alone can activate all Th2 effector functions. These mice reveal distinct spatial, temporal, and hierarchical cytokine requirements in immune function.