A new lineage of effector/memory CD4+ T cells has been identified whose signature products are IL‐17 cytokines and whose differentiation requires the nuclear receptor, RORγt. These Th17 cells are critical effectors in mouse models of autoimmune disease. We have analyzed the association between chemokine receptor expression and IL‐17 production for human T cells. Activating cord blood (naïve) CD4+ T cells under conditions driving Th17 differentiation led to preferential induction of CCR6, CCR9 and CXCR6. Despite these data, we found no strong correlation between the production of IL‐17 and expression of CCR9 or CXCR6. By contrast, virtually all IL‐17‐producing CD4+ T cells, either made in our in vitro or found in peripheral blood, expressed CCR6. Compared with CD4+CD45RO+CCR6− cells, CD4+CD45RO+CCR6+ cells contained at least 100‐fold more IL‐17A mRNA and secreted 100‐fold more IL‐17 protein. The CCR6+ cells showed a similar enrichment in mRNA for RORγt. CCR6 was likewise expressed on all IL‐17‐producing CD8+ PBL. CCR6 has been associated with the trafficking of T, B, and dendritic cells to epithelial sites, but has not been linked to a specific T cell phenotype. Our data reveal a fundamental feature of IL‐17‐producing human T cells and a novel role for CCR6, suggesting both new directions for investigating IL‐17‐related immune responses and possible targets for preventing inflammatory injury. Research support: NIAID, NIH
Dendritic cells (DCs) have been implicated in the pathogenesis of psoriasis but the roles for specific DC subsets are not well defined. Here we show that DCs are required for psoriasis-like changes in mouse skin induced by the local injection of IL-23. However, Flt3L-dependent DCs and resident Langerhans cells are dispensable for the inflammation. In epidermis and dermis, the critical DCs are TNF-producing and IL-1β-producing monocyte-derived DCs, including a population of inflammatory Langerhans cells. Depleting Ly6Chi blood monocytes reduces DC accumulation and the skin changes induced either by injecting IL-23 or by application of the TLR7 agonist imiquimod. Moreover, we find that IL-23-induced inflammation requires expression of CCR6 by DCs or their precursors, and that CCR6 mediates monocyte trafficking into inflamed skin. Collectively, our results imply that monocyte-derived cells are critical contributors to psoriasis through production of inflammatory cytokines that augment the activation of skin T cells.
The interaction of Borrelia burgdorferi, the causative agent of Lyme borreliosis, with phagocytic cells induces the activation of NF-B and the expression of proinflammatory cytokines including tumor necrosis factor alpha (TNF-␣). B. burgdorferi-induced TNF-␣ production is also dependent on the activation of p38 mitogenactivated protein (MAP) kinase. The specific contribution of these signaling pathways to the response of phagocytic cells to the spirochete and the molecular mechanisms underlying this response remain unresolved. We now show that p38 MAP kinase activity regulates the transcriptional activation of NF-B in response to spirochetal lysate stimulation of phagocytic cells. The regulation occurs at the nuclear level and is independent of the translocation of the transcription factor to the nucleus or its capacity to bind to specific DNA target sequences. In RAW264.
Borrelia burgdorferi, the causative agent of Lyme disease, shows a great ability to adapt to different environments, including the arthropod vector, and the mammalian host. The success of these microorganisms to survive in nature and complete their enzootic cycle depends on the regulation of genes that are essential to their survival in the different environments. This review describes the current knowledge of gene expression by B. burgdorferi in the tick and the mammalian host. The functions of the differentially regulated gene products as well as the factors that influence their expression are discussed. A thorough understanding of the changes in gene expression and the function of the differentially expressed antigens during the life cycle of the spirochete will allow a better control of this prevalent infection and the design of new, second generation vaccines to prevent infection with the spirochete.
Importance of the field
Psoriasis is a common, chronic autoimmune disease of the skin. Despite a number of effective treatments, new therapies are needed with enhanced efficacy, safety, and convenience. Chemokine receptors are G protein-coupled receptors that control leukocyte trafficking, and like other G protein-coupled receptors, are good potential drug targets. The chemokine receptor CCR6 is expressed on the Th17 subset of CD4+ T cells, which produces IL-17A/F, IL-22, TNF-α and other cytokines, and which has been implicated in the pathogenesis of psoriasis. CCR6 and its ligand, CCL20/MIP-3α, are highly expressed in psoriatic skin and CCR6 is necessary for the pathology induced in a mouse model of psoriasis-like inflammation.
Areas covered in this review
This review will summarize the evidence for the importance of the IL-23/Th17 axis, and in particular CCR6 and CCL20 in psoriasis, dating from 2000 to the present, and discuss the possibility of inhibiting CCR6 as treatment for the disease.
What the reader will gain
The review will inform the reader of the current thinking on the mechanisms of inflammation in psoriasis and the possible roles for CCR6 (and CCL20) in disease pathogenesis.
Take home message
We conclude that CCR6 should be investigated as a potential therapeutic target in psoriasis.
The 2019 13th Workshop on Recent Issues in Bioanalysis (WRIB) took place in New Orleans, LA, USA on April 1–5, 2019 with an attendance of over 1000 representatives from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a 5-day, week-long event – a full immersion week of bioanalysis, biomarkers, immunogenicity and gene therapy. As usual, it was specifically designed to facilitate sharing, reviewing, discussing and agreeing on approaches to address the most current issues of interest including both small- and large-molecule bioanalysis involving LCMS, hybrid LBA/LCMS, LBA cell-based/flow cytometry assays and qPCR approaches. This 2019 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2019 edition of this comprehensive White Paper has been divided into three parts for editorial reasons. This publication (Part 3) covers New Insights in Biomarker Assay Validation, Current & Effective Strategies for Critical Reagent Management, Flow Cytometry Validation in Drug Discovery & Development & CLSI H62, Interpretation of the 2019 FDA Immunogenicity Guidance and Gene Therapy Bioanalytical Challenges. Part 1 (Innovation in Small Molecules and Oligonucleotides & Mass Spectrometry Method Development Strategies for Large Molecule Bioanalysis) and Part 2 (Recommendations on the 2018 FDA BMV Guidance, 2019 ICH M10 BMV Draft Guideline and regulatory agencies' input on bioanalysis, biomarkers, immunogenicity and gene therapy) are published in volume 11 of Bioanalysis, issues 22 and 23 (2019), respectively.
PurposeDecreased expression of HLA‐DR on monocytes (mHLA‐DR) is a reliable indicator of immunosuppression in patients with sepsis and is correlated with increased risk of secondary infection and mortality. A flow cytometry‐based laboratory developed test for the measurement of mHLA‐DR in whole blood was validated for clinical trial enrollment, which is considered medical decision‐making, for patients with severe sepsis or septic shock.MethodsThe BD Quantibrite™ anti‐HLA‐DR/anti‐monocyte reagent measures antibodies bound per cell of HLA‐DR on CD14+ monocytes. The mHLA‐DR assay was planned to support inclusion/exclusion of patients for a clinical trial and was validated according to New York State Department of Health (NYSDOH) requirements for a new non‐malignant leukocyte immunophenotyping assay.ResultsNormal, healthy donor and sepsis patient samples were stable up to 72 h post‐collection in Cyto‐Chex BCT phlebotomy tubes. Pre‐determined acceptance criteria were met for precision parameters (average %CV ≤ 20%) and global laboratory‐to‐laboratory comparisons (average %Δ ≤ 20%). The approaches taken to evaluate and report accuracy, analytical specificity and sensitivity, reportable range, reference interval, and the proposed multi‐level quality control were accepted by NYSDOH.ConclusionsIn this study, the validation strategy necessary when the intended use of assay results changes from exploratory to medical decision making (patient enrollment), which successfully resulted in regulatory approval, is described.
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