70 research outputs found
Regulatory T Cell Responses in Participants with Type 1 Diabetes after a Single Dose of Interleukin-2: A Non-Randomised, Open Label, Adaptive Dose-Finding Trial
BACKGROUND: Interleukin-2 (IL-2) has an essential role in the expansion and function of CD4+ regulatory T cells (Tregs). Tregs reduce tissue damage by limiting the immune response following infection and regulate autoreactive CD4+ effector T cells (Teffs) to prevent autoimmune diseases, such as type 1 diabetes (T1D). Genetic susceptibility to T1D causes alterations in the IL-2 pathway, a finding that supports Tregs as a cellular therapeutic target. Aldesleukin (Proleukin; recombinant human IL-2), which is administered at high doses to activate the immune system in cancer immunotherapy, is now being repositioned to treat inflammatory and autoimmune disorders at lower doses by targeting Tregs. METHODS AND FINDINGS: To define the aldesleukin dose response for Tregs and to find doses that increase Tregs physiologically for treatment of T1D, a statistical and systematic approach was taken by analysing the pharmacokinetics and pharmacodynamics of single doses of subcutaneous aldesleukin in the Adaptive Study of IL-2 Dose on Regulatory T Cells in Type 1 Diabetes (DILT1D), a single centre, non-randomised, open label, adaptive dose-finding trial with 40 adult participants with recently diagnosed T1D. The primary endpoint was the maximum percentage increase in Tregs (defined as CD3+CD4+CD25highCD127low) from the baseline frequency in each participant measured over the 7 d following treatment. There was an initial learning phase with five pairs of participants, each pair receiving one of five pre-assigned single doses from 0.04 × 106 to 1.5 × 106 IU/m2, in order to model the dose-response curve. Results from each participant were then incorporated into interim statistical modelling to target the two doses most likely to induce 10% and 20% increases in Treg frequencies. Primary analysis of the evaluable population (n = 39) found that the optimal doses of aldesleukin to induce 10% and 20% increases in Tregs were 0.101 × 106 IU/m2 (standard error [SE] = 0.078, 95% CI = -0.052, 0.254) and 0.497 × 106 IU/m2 (SE = 0.092, 95% CI = 0.316, 0.678), respectively. On analysis of secondary outcomes, using a highly sensitive IL-2 assay, the observed plasma concentrations of the drug at 90 min exceeded the hypothetical Treg-specific therapeutic window determined in vitro (0.015-0.24 IU/ml), even at the lowest doses (0.040 × 106 and 0.045 × 106 IU/m2) administered. A rapid decrease in Treg frequency in the circulation was observed at 90 min and at day 1, which was dose dependent (mean decrease 11.6%, SE = 2.3%, range 10.0%-48.2%, n = 37), rebounding at day 2 and increasing to frequencies above baseline over 7 d. Teffs, natural killer cells, and eosinophils also responded, with their frequencies rapidly and dose-dependently decreased in the blood, then returning to, or exceeding, pretreatment levels. Furthermore, there was a dose-dependent down modulation of one of the two signalling subunits of the IL-2 receptor, the β chain (CD122) (mean decrease = 58.0%, SE = 2.8%, range 9.8%-85.5%, n = 33), on Tregs and a reduction in their sensitivity to aldesleukin at 90 min and day 1 and 2 post-treatment. Due to blood volume requirements as well as ethical and practical considerations, the study was limited to adults and to analysis of peripheral blood only. CONCLUSIONS: The DILT1D trial results, most notably the early altered trafficking and desensitisation of Tregs induced by a single ultra-low dose of aldesleukin that resolves within 2-3 d, inform the design of the next trial to determine a repeat dosing regimen aimed at establishing a steady-state Treg frequency increase of 20%-50%, with the eventual goal of preventing T1D. TRIAL REGISTRATION: ISRCTN Registry ISRCTN27852285; ClinicalTrials.gov NCT01827735.This is the final version of the article. It first appeared from the Public Library of Science via http://dx.doi.org/10.1371/journal.pmed.100213
The initial somitic phase of Myf5 expression requires neither Shh signaling nor Gli regulation
Myf5, the skeletal muscle determination gene, is first expressed in the dorso-medial aspect of the somite under the control of an element we have called the early epaxial enhancer. It has subsequently been reported that this enhancer is a direct target of Shh signaling mediated by Gli transcription factors (Gustafsson et al. 2002). We here demonstrate that activation of Myf5 expression depends on neither Shh function nor an intact Gli binding site, although the Gli site is necessary for continuation of expression. We suggest that the discrepancy is due to the existence of specific interactions between the enhancer and the Myf5 promoter
Global transcriptional regulation of the locus encoding the skeletal muscle determination genes Mrf4 and Myf5
The linked Mrf4 and Myf5 genes encode two transcription factors essential for the determination and differentiation of skeletal muscle in the embryo. The locus is controlled by a multitude of interdigitated enhancers that activate gene expression at different times and in precisely defined progenitor cell populations. Manipulation of the enhancer–promoter composition of the locus reveals a novel mechanism for the regulation of such a gene cluster. Enhancers, promoters, and a new class of elements we call transcription balancing sequences, which can act as cryptic promoters, exist in a series of equilibria to ensure that enhancers and promoters together produce the highly dynamic and exquisitely specific expression patterns of the two genes. The proposed model depends upon nonproductive interactions between enhancers and both minimal and cryptic promoters, and is distinct from those developed for the β-globin and Hox clusters. Moreover, it provides an explanation for the unexpected phenotypes of the three Mrf4 knockout alleles
Advancing ocean monitoring near coral reefs
[Extract] Because of the sensitivity of corals to environmental factors, bleaching events are seen\ud
as indicators of the changing state of the world’s oceans as climate warms. In 1997–1998, a worldwide bleaching event occurred. Since then, bleaching has been observed in\ud
every ocean basin with increased frequency and severity. For example, in 2010 reefs in Southeastern Asia bleached at record levels, parts of the Hawaiian archipelago have\ud
experienced mild bleaching, and current monitoring and forecasts indicate significant to severe bleaching in the Caribbean.\ud
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Observing the physical properties of ocean waters around coral reefs provides important insights for linking environmental changes to such biological consequences.\ud
Remotely sensed data are particularly valuable, providing broad spatial coverage in a timely fashion to inform\ud
actions by reef managers. However, there remain significant gaps in monitoring capability and scientific understanding of coral ecosystem responses to changes in the physical environment.\u
Efficacy and safety of tabalumab, an anti-B-cell-activating factor monoclonal antibody, in patients with rheumatoid arthritis who had an inadequate response to methotrexate therapy: results from a phase III multicentre, randomised, double-blind study
Pathophysiology and treatment of rheumatic disease
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