Human dendritic cells infected with an adenoviral vector suppress proliferation of autologous and allogeneic T cells.

Dendritic cells (DCs) play a key role in the type and course of an immune response. The manipulation of human DCs to produce therapeutic agents by transduction with viral vectors is a growing area of research. We present an investigation into the effects of adenoviral vector infection on human DCs and other cell types, and on their subsequent ability to induce T-cell proliferation. We show that infection with replication-deficient adenovirus results in impaired proliferation of T cells in a mixed lymphocyte reaction (MLR). We show this to be an active suppression rather than a defect in the DCs as T cells also fail to proliferate in response to phytohaemagglutinin in the presence of adenoviral vector-infected DCs. This suppression is not attributable to phenotypic changes, death or inability of the DCs to produce cytokines on stimulation. By separation of DCs from T cells, and addition of conditioned supernatants, we show that suppression is mediated by a soluble factor. Blocking of interleukin (IL)-10 but not transforming growth factor (TGF)-beta could overcome the suppressive effect in some donors, and the source of the suppressive IL-10 was lymphocytes exposed to conditioned supernatant. Together our data suggest that infection of DCs by adenoviral vectors leads to suppression of the resulting immune response.

Interleukin-17-producing T cells are enriched in the joints of children with arthritis, but have a reciprocal relationship to regulatory T cell numbers.

OBJECTIVE: To identify interleukin-17 (IL-17)-producing T cells from patients with juvenile idiopathic arthritis (JIA), and investigate their cytokine production, migratory capacity, and relationship to Treg cells at sites of inflammation, as well as to test the hypothesis that IL-17+ T cell numbers correlate with clinical phenotype in childhood arthritis. METHODS: Flow cytometry was used to analyze the phenotype, cytokine production, and chemokine receptor expression of IL-17-producing T cells in peripheral blood and synovial fluid mononuclear cells from 36 children with JIA, in parallel with analysis of forkhead box P3 (FoxP3)-positive Treg cells. Migration of IL-17+ T cells toward CCL20 was assessed by a Transwell assay. Synovial tissue was analyzed by immunohistochemistry for IL-17 and IL-22. RESULTS: IL-17+ T cells were enriched in the joints of children with JIA as compared with the blood of JIA patients (P = 0.0001) and controls (P = 0.018) and were demonstrated in synovial tissue. IL-17+ T cell numbers were higher in patients with extended oligoarthritis, the more severe subtype of JIA, as compared with patients with persistent oligoarthritis, the milder subtype (P = 0.046). Within the joint, there was an inverse relationship between IL-17+ T cells and FoxP3+ Treg cells (r = 0.61, P = 0.016). IL-17+,CD4+ T cells were uniformly CCR6+ and migrated toward CCL20, but synovial IL-17+ T cells had variable CCR4 expression. A proportion of IL-17+ synovial T cells produced IL-22 and interferon-gamma. CONCLUSION: This study is the first to define the frequency and characteristics of "Th17" cells in JIA. We suggest that these highly proinflammatory cells contribute to joint pathology, as indicated by relationships with clinical phenotypes, and that the balance between IL-17+ T cells and Treg cells may be critical to outcome.

Quantification of normal range of inflammatory changes in morphologically normal pediatric muscle.

The aim of this study was to define normal ranges of histological features in pediatric muscle in comparison with muscle demonstrating inflammatory changes. Sixteen pediatric muscle biopsy samples, considered normal by standard histology, were analyzed for the presence of inflammatory cells, and the expression of neonatal myosin and major histocompatibility complex (MHC) Class 1. Normal findings were defined for each feature. These data will facilitate quantitative analysis of inflammatory changes in pediatric muscle biopsy.

International consensus on a proposed score system for muscle biopsy evaluation in patients with juvenile dermatomyositis: a tool for potential use in clinical trials.

OBJECTIVE: To devise and test a system with which to evaluate abnormalities on muscle biopsy samples obtained from children diagnosed with juvenile dermatomyositis (DM). METHODS: We established an International Consensus Group on Juvenile DM Biopsy and carried out 2 phases of consensus process and scoring workshops. Biopsy sections (n = 33) were stained by standard methods. The scoring tool was based on 4 domains of change: inflammatory, vascular, muscle fiber, and connective tissue. Using a Latin square design, biopsy samples were scored by 11 experts for items in each domain, and for a global abnormality measure using a 10-cm visual analog score (VAS 0-10). The tool's reliability was assessed using an intraclass correlation coefficient (ICC) and scorer agreement (alpha) by determining variation in scorers' ratings. RESULTS: There was good agreement in many items of the tool, and several items refined between the meetings improved in reliability and/or agreement. The inflammatory and muscle fiber domains had the highest reliability and agreement. The overall VAS score for abnormality had high agreement and reliability, reaching an ICC of 0.863 at the second consensus meeting. CONCLUSION: We propose a provisional scoring system to measure abnormalities on muscle biopsy samples obtained from children with juvenile DM. This system needs to be validated, and then could be used in prospective studies to test which features of muscle pathology are prognostic of disease course or outcome. We suggest that the process we used could be a template for developing similar systems in other forms of myositis.

Expression of the inflammatory chemokines CCL5, CCL3 and CXCL10 in juvenile idiopathic arthritis, and demonstration of CCL5 production by an atypical subset of CD8+ T cells.

This study focuses upon three chemokines, namely CCL5, CXCL10 and CCL3, which are potential novel therapeutic targets in arthritis. The aim of the study was to analyse the expression and production of these three chemokines within the joints of children with juvenile idiopathic arthritis (JIA) of the oligoarticular and polyarticular subtypes. All three of these chemokines are highly expressed at the level of mRNA, with the most significant increase in mRNA levels being demonstrated for CCL5 when compared with matched peripheral blood samples and controls. We show that high levels of all three chemokines are present in synovial fluid of children with JIA. We investigate the major source of CCL5 from inflammatory synovial cells, which we show to be CD8+ T cells. This CD8+ synovial T cell population has an unexpected phenotype that has not been described previously, being CCR7- yet predominantly CD28+ and CD45RA-. These cells contain high levels of stored intracellular CCL5, and rapid release of CCL5 takes place on T cell stimulation, without requiring new protein synthesis. In addition, we demonstrate that CCL5 is present in synovial biopsies from these patients, in particular on the endothelium of small and medium sized vessels. We believe this to be the first in depth analysis of these mediators of inflammation in JIA.