Prostaglandin E2 affects T cell responses through modulation of CD46 expression

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Calcitriol modulates the CD46 pathway in T cells

The complement regulator CD46 is a costimulatory molecule for human T cells that induces a regulatory Tr1 phenotype, characterized by large amounts of IL-10 secretion. Secretion of IL-10 upon CD46 costimulation is largely impaired in T cells from patients with multiple sclerosis (MS). Vitamin D can exert a direct effect on T cells, and may be beneficial in several pathologies, including MS. In this pilot study, we examined whether active vitamin D (1,25(OH)2D3 or calcitriol) could modulate the CD46 pathway and restore IL-10 production by CD46-costimulated CD4+ T cells from patients with MS. In healthy T cells, calcitriol profoundly affects the phenotype of CD46-costimulated CD4+ T cells, by increasing the expression of CD28, CD25, CTLA-4 and Foxp3 while it concomitantly decreased CD46 expression. Similar trends were observed in MS CD4+ T cells except for CD25 for which a striking opposite effect was observed: while CD25 was normally induced on MS T cells by CD46 costimulation, addition of calcitriol consistently inhibited its induction. Despite the aberrant effect on CD25 expression, calcitriol increased the IL-10:IFNc ratio, characteristic of the CD46-induced Tr1 phenotype, in both T cells from healthy donors and patients with MS. Hence, we show that calcitriol affects the CD46 pathway, and that it promotes anti-inflammatory responses mediated by CD46. Moreover, it might be beneficial for T cell responses in MS

Potenziale und Restriktionen des Gewächshausanbaus in Vorderasien : Potenzialanalyse und Wirkungsfolgenabschätzung einer forcierten Implementierung des Gewächshausanbaus in ariden Gebieten

Für eine Wirkungsabschätzung der forcierten Einführung von Gewächshäusern wurde eine Potenzial- und Restriktionsanalyse aufbauend auf einer Literaturrecherche durchgeführt. Grundsätzlich gestattet der Gewächshausanbau unter den in Vorderasien häufigen ariden und semi-ariden Situationen trotz erheblicher Intensitätssteigerung eine deutliche Verringerung des Wassereinsatzes. Es sind Lösungsansätze vorhanden, die dazu beitragen können, dort positive Entwicklungspotenziale zu entfalten und die negativen Entwicklungen zu verhindern. Dennoch ist das Gewächshaus kein Allheilmittel. Insbesondere die Vermittlung bzw. regionale Anpassung von Wissen (auch zum Pflanzenschutz), der Erhalt geeigneter Sorten und der Zugang der Landwirte zu diesen sind starke Hemmnisse. Flankierende staatliche und private Fördermaßnahmen sowie neue institutionelle Arrangements bzw. Governancestrukturen erlauben, nachteilige Entwicklungen zu vermeiden und den Erhalt von Ökosystemleistungen zu fördern.In order to obtain an impact assessment of the introduction of greenhouse production and its sustainability in the Middle East an analysis for potentials and restrictions was done based on literature search. This innovation generally allows for an improved income generation and a commercialization and orientation towards export in agriculture. Furthermore, the utilization of unproductive locations becomes possible while potentially raising the resource productivity at the same time. Greenhouse production means a significant reduction of water use in agriculture within the frequently found arid and semi-arid situations in the Middle East even though enabling a serious efficiency improvement. Never the less it is not a universal remedy. Restrictions to be considered are the necessity of knowledge transfer respectively the adaption of knowledge (also with respect to plant protection), the preservation of suitable varieties and the access for farmers to this agrobiodiversity. Never the less there are tentative solutions that are assessed to be highly beneficial for sustainable cultivation and that can contribute to unfold positive development potentials and avoid negative developments. This has to be accompanied by government incentives and private subsidies as well as institutional arrangements respectively governance structures in order to avoid the disadvantages of greenhouse production and to secure existing eco system services

Calcitriol promotes CTLA-4, Foxp3 and CD25 expression on CD4+ T cells but not in MS.

<p>(<b>A</b>) Purified CD4+ T cells from MS patients or healthy controls (HC) were left unstimulated or stimulated by immobilized anti-CD3 or anti-CD3/CD46 antibodies in presence of calcitriol (10⁻⁷M) or ethanol, for 5 days. Expression of CTLA-4, Foxp3 and CD25 was then monitored by flow cytometry. (<b>B</b>) The representative data showing the concomitant increase in CD25 or CTLA-4 with the downregulation of CD46 upon CD3/CD46 costimulation for one healthy donor are shown. (<b>C</b>) The representative data showing changes in CD25 expression following addition of calcitriol in one healthy donor and one patient with MS are shown.</p

Calcitriol allows the switch from Th1 to Tr1 in CD4+ T cells.

<p>(<b>A</b>) Purified CD4+ T cells from one healthy donor were left unstimulated or stimulated as indicated by immobilized anti-CD3 and anti-CD3/CD46 antibodies, in presence or absence of IL-2 and calcitriol. After 2 days, the production of IL-10 and IFNγ was assessed using the secretion catch assay (Miltenyi). (<b>B</b>) The production of IL-10 and IFNγ in the supernatants from the same wells was also determined by ELISA. The IL-10:IFNγ ratio is also represented (mean ± SEM; samples were analyzed using Student's t-test).</p

Calcitriol-treated cell supernatants decrease proliferation of bystander CD4+ T cells.

<p>(<b>A</b>) Purified CD4+ T cells were CFSE pre-labeled and then activated by anti-CD3 or anti-CD3/CD28 antibodies, in presence or absence of culture supernatants from CD46-costimulated T cells with or without calcitriol from either a healthy donor or a patient with MS, as indicated. Proliferation was assessed by flow cytometry after 3 days. (<b>B</b>) The data obtained with the supernatants from CD46-costimulated T cells from 3 healthy donors are represented. (<b>C</b>) CFSE-labeled naïve T cells were activated by anti-CD3 antibodies (1 µg/ml), in presence of cell supernatants from CD46-costimulated T cells with or without calcitriol (n = 3). A blocking anti-IL-10 antibody or control IgG1 was added to the culture. Proliferation was assessed after 3 days.</p

Calcitriol promotes concomitant CD46 downregulation and CD28 upregulation in CD46-costimulated CD4+ T cells.

<p>Purified CD4+ T cells from a cohort of RRMS patients (MS) (n = 11) or healthy controls (HC) (n = 15) were stimulated by immobilized anti-CD3 or anti-CD3/CD46 antibodies as indicated in presence of calcitriol (10⁻⁷M) or ethanol as vehicle control for 5 days. Expression of CD46 (<b>A</b>) or CD28 (<b>B</b>) was monitored by flow cytometry. Samples were analyzed using the Wilcoxon test. (<b>C</b>) The dot-plot showing the concomitant changes in expression of CD46 and CD28 following calcitriol treatment on CD46-costimulated T cells is represented for one healthy donor.</p

Calcitriol modulates CD46 expression in CD4+ T cells.

<p>Purified CD4+ T cells from healthy donors were left unstimulated (US), or were stimulated by immobilized anti-CD3, anti-CD3/CD28, or anti-CD3/CD46 antibodies as indicated in presence of calcitriol (10⁻⁷M) or ethanol as vehicle control. CD46 expression was monitored by flow cytometry. The representative expression of CD46 after 5 days of culture is shown in (<b>A</b>). The average expression of CD46 detected after 2 or 5 days for the different donors analyzed (mean ± SEM; n = 15) is shown in (<b>B</b>). Samples were analyzed using the Wilcoxon test.</p

Characteristics of the donors used in this study as to sex, age and disease status.

<p>Characteristics of the donors used in this study as to sex, age and disease status.</p

Calcitriol restores the IL-10:IFNγ ratio upon CD46 costimulation of CD4+ T cells in MS.

<p>Purified CD4+ T cells from healthy controls (HC) or RRMS patients (MS) were left unstimulated or were stimulated as indicated by immobilized antibodies for 4 days, in presence or absence of calcitriol (10⁻⁷M). (<b>A</b>) Proliferation was determined by ³H incorporation. The levels of IL-10 (<b>B</b>) and IFNγ (<b>C</b>) in the supernatants were determined by ELISA (mean ± SEM; samples were analyzed using the Wilcoxon test). (<b>D</b>) The IL-10:IFNγ ratio is also represented to bypass the change related to differences in proliferation (mean ± SEM; samples were compared using the Mann Whitney U-test).</p