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.