We show that a combination of the immunosuppressive drugs, vitamin D3 and Dexamethasone, induced human and mouse naive CD4+ T cells to differentiate in vitro into regulatory T cells. In contrast to the previously described in vitro derived CD4+ T cells, these cells produced only interleukin (IL)-10, but no IL-5 and interferon (IFN)-γ, and furthermore retained strong proliferative capacity. The development of these IL-10–producing cells was enhanced by neutralization of the T helper type 1 (Th1)- and Th2–inducing cytokines IL-4, IL-12, and IFN-γ. These immunosuppressive drugs also induced the development of IL-10–producing T cells in the absence of antigen-presenting cells, with IL-10 acting as a positive autocrine factor for these T cells. Furthermore, nuclear factor (NF)-κB and activator protein (AP)-1 activities were inhibited in the IL-10–producing cells described here as well as key transcription factors involved in Th1 and Th2 subset differentiation. The regulatory function of these in vitro generated IL-10–producing T cells was demonstrated by their ability to prevent central nervous system inflammation, when targeted to the site of inflammation, and this function was shown to be IL-10 dependent. Generating homogeneous populations of IL-10–producing T cells in vitro will thus facilitate the use of regulatory T cells in immunotherapy.

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Rationale-Little is known about vitamin D status and its effect on asthma pathophysiology in children with severe, therapy-resistant asthma (STRA).Objectives-Relationships between serum vitamin D, lung function, and pathology were investigated in pediatric STRA. Methods-Serum 25-hydroxyvitamin D [25(OH)D3 ] was measured in 86 children (mean age, 11.7 yr): 36 with STRA, 26 with moderate asthma (MA), and 24 without asthma (control subjects). Relationships between 25(OH)D 3 , the asthma control test (ACT), spirometry, corticosteroid use, and exacerbations were assessed. Twenty-two of 36 children with STRA underwent fiberoptic bronchoscopy, bronchoalveolar lavage, and endobronchial biopsy with assessment of airway inflammation and remodeling. Measurements and Main Results-25(OH)D 3 levels (median [IQR]) were significantly lower in nmol/L) than in nmol/L) and control subjects (56.5 [45-67] nmol/L) (P < 0.001). There was a positive relationship between 25(OH)D 3 levels and percent predicted FEV 1 (r = 0.4, P < 0.001) and FVC (r = 0.3, P = 0.002) in all subjects. 25(OH)D 3 levels were positively associated with ACT (r = 0.6, P < 0.001), and inversely associated with exacerbations (r=−0.6, P < 0.001) and inhaled steroid dose (r=−0.39, P = 0.001) in MA and and STRA. Airway smooth muscle (ASM) mass, but not epithelial shedding or reticular basement membrane thickness, was inversely related to 25(OH)D 3 levels (r=−0.6, P = 0.008). Copyright © 2011 by the American Thoracic SocietyCorrespondence and requests for reprints should be addressed to Atul Gupta, M.D., Department of Paediatric Respiratory Medicine, Royal Brompton Hospital, Sydney Street, London SW3 6NP, UK. atulgupta@doctors.org.uk. Author Contributions: A.G. recruited the majority of the patients, collected patient samples, conducted the majority of the experiments, analyzed the data, and took the lead on writing the manuscript. A.S. performed some of the experimental work. A.G., A.B., C.H., and S.S. conceptualized, delineated the hypotheses, and designed the experiments A.B., C.H., D.R., and S.S. contributed to the interpretation of the analyses, supervised the project, and helped with revising the manuscript. A.B. and S.S. also performed bronchoscopies and obtained samples. W.B. performed some of the statistical analyses. There was a positive correlation between ASM mass and bronchodilator reversibility (r = 0.6, P = 0.009) and an inverse correlation between ASM mass and ACT (r = −0.7, P < 0.001). Author DisclosuresConclusions-Lower vitamin D levels in children with STRA were associated with increased ASM mass and worse asthma control and lung function. The link between vitamin D, airway structure, and function suggests vitamin D supplementation may be useful in pediatric STRA. Keywordsvitamin D; asthma; remodeling; airway smooth muscle; pediatrics For most children with ready access to healthcare, asthma can be controlled with low doses of inhaled steroids. There remains, however, a significant number of individuals with asthma who, despite apparentl...

The mode of action of Leflunomide, an immunomodulatory drug used in rheumatoid arthritis, is debated. This study, using 14 C-labeled de novo purine and pyrimidine synthesis precursors, proves conclusively that the prime target in proliferating human T-lymphocytes is pyrimidine biosynthesis at the level of dihydroorotic- 14 C]Glycine studies confirmed that restriction of de novo purine synthesis occurred secondary to inhibition of proliferation since this was reversed by uridine rescue, except at 100 M Leflunomide. 100 M Leflunomide markedly depleted ATP and GTP pools also, which would have serious consequences for ATP-dependent enzymes essential to the immune response, thereby explaining non-pyrimidinerelated effects reported for Leflunomide at 100 M and above.

1α,25-Dihydroxyvitamin D3 (1α25VitD3) has potent immunomodulatory properties. We have previously demonstrated that 1α25VitD3 promotes human and murine IL-10-secreting CD4 + T cells. Because of the clinical relevance of this observation, we characterized these cells further and investigated their relationship with Foxp3 + regulatory T (Treg) cells. 1α25VitD3 increased the frequency of both Foxp3 + and IL-10 + CD4 + T cells in vitro. However, Foxp3 was increased at high concentrations of 1α25VitD3 and IL-10 at more moderate levels, with little coexpression of these molecules. The Foxp3 + and IL-10 + T-cell populations showed comparable suppressive activity. We demonstrate that the enhancement of Foxp3 expression by 1α25VitD3 is impaired by IL-10. 1α25VitD3 enables the selective expansion of Foxp3 + Treg cells over their Foxp3 − T-cell counterparts. Equally, 1α25VitD3 maintains Foxp3 + expression by sorted populations of human and murine Treg cells upon in vitro culture. A positive in vivo correlation between vitamin D status and CD4 + Foxp3 + T cells in the airways was observed in a severe pediatric asthma cohort, supporting the in vitro observations. In summary, we provide evidence that 1α25VitD3 enhances the frequency of both IL-10 + and Foxp3 + Treg cells. In a translational setting, these data suggest that 1α25VitD3, over a broad concentration range, will be effective in enhancing the frequency of Treg cells.Keywords: 1α,25-Dihydroxyvitamin D3 r Asthma r Immune regulation r Regulatory T cells Supporting Information available online IntroductionConsiderable interest exists in the therapeutic potential of regulatory T (Treg) cells to treat a range of immune-mediated patholoCorrespondence: Dr. Catherine M. Hawrylowicz e-mail: catherine.hawrylowicz@kcl.ac.uk gies in humans. This is partly based on evidence obtained from animal models of human disease demonstrating the capacity of Treg cells to control transplant rejection, and to successfully treat autoimmune and allergic disease [1]. Two broad therapeutic * These authors contributed equally to this work. [11]. These studies demonstrate a correlation between therapeutic efficacy and increased frequency or quantities of CD4 + CD25 + T cells, IL-10, TGF-β, and CTLA-4.Our earlier studies have highlighted the capacity of 1α25VitD3 to promote human CD4 + IL-10 secreting Treg cells (IL-10-Treg) in culture both alone [12] and in concert with glucocorticoids such as dexamethasone [13,14]. Furthermore, treatment of severe steroid refractory asthma patients with 1α25VitD3 in vivo directly increased IL-10 gene expression in CD3 + CD4 + T cells [12], and restored the impaired steroid-induced IL-10 response in CD4 + cells in vitro [14,15].The present study was designed to further investigate the mechanisms underlying the therapeutic potential of 1α25VitD3 in the context of asthmatic disease, and to determine effects on the induction of both IL-10 + and Foxp3 + T cells. Specifically, we have examined the effects of 1α25VitD3 on total, unfractionated CD4 + T-cell populations, r...

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Although previous studies have found evidence for an association between maternal smoking and child behavior problems, the strength of this study lies in its size, its detailed and consistent measurement of maternal smoking, and its ability to control for many social and biological factors linked to maternal smoking and child behavior. (ABSTRACT TRUNCATED)

PBMC cultures from asthma patients synthesised high levels of IL-17A compared to non-asthmatic controls, most significantly in steroid refractory patients. Glucocorticoids could enhance IL-17A, but 1,25(OH)2D3 inhibited this response in a glucocorticoid-independent manner. Nanzer et al 3 AbstractBackground: Th17 cells are proposed to play a role in the pathology of asthma, including steroid