Abstract
In addition to its well defined role as a key regulator of calcium and bone metabolism, 1,25-dihydroxyvitamin D3 (calcitriol) has been established as a potent modulator of immune cell function. Still, because of the hypercalcemic toxicity occurring after systemic application of the parent compound, its clinical application as an immunosuppressant has been hampered. Recently, we described 22-ene-25-oxa-vitamin D (ZK156979) as a representative of a novel class of low calcemic vitamin D analogs with well preserved immunosuppressive activity in vitro. Here, in vivo colitis was induced by applying a rectal enema of 2,4,6-trinitrobenzene sulfonic acid (TNBS) to male BALB/c mice, and calcitriol (0.2 μg/kg) or ZK156979 (0.1–2.0 μg/kg) was given i.p. from days 0 to 3 or 3 to 5. Body mass and clinical activity score of colitis were recorded daily. Colon tissue was analyzed macroscopically and microscopically, myeloperoxidase activity and cytokine levels [tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-10, and IL-4] were determined by enzyme-linked immunosorbent assay, and T-box transcription factor (T-bet) expression was determined by immunoblot analysis. We found that treatment with ZK156979 clearly reduced the severity of TNBS-induced colitis without exhibiting calcemic effects. Both early and late treatment abrogated body weight loss, diarrhea, and macroscopic intestinal inflammation with a potency comparable with that of calcitriol. The therapeutic effect of ZK156979 was accompanied by a down-regulation of myeloperoxidase activity, TNF-α, IFN-γ, and T-bet expression decreased, whereas local tissue IL-10 and IL-4 protein levels increased. To conclude, our data provide the first clear evidence that ZK156979 exhibits a beneficial prophylactic as well as therapeutic profile in T helper cell type 1-like experimental colitis, offering new therapeutic options for the treatment of human inflammatory bowel diseases.
Footnotes
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This study was supported by the Else Kroener-Fresenius-Foundation, Bad Homburg (Germany). H.H.R. is supported by the Dr.-Hans-Schleussner Foundation. C.D. is supported by the Deutsche Forschungsgemeinschaft (GRK 757).
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.106.107599.
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ABBREVIATIONS: VDR, vitamin D receptor; Th1, T helper cell type 1; Th2, T helper cell type 2; DC, dendritic cell; ZK156979, 22-ene-25-oxa-vitamin D; PBMC, peripheral blood mononuclear cell; CD, Crohn's disease; TNBS, trinitrobenzene sulfonic acid; MPO, myeloperoxidase; IFN, interferon; TNF, tumor necrosis factor; T-bet, T-box transcription factor; IL, interleukin; IBD, inflammatory bowel disease; GPR30, G protein-coupled receptor 30 involved in rapid nongenomic estrogen-mediated signaling.
- Received May 15, 2006.
- Accepted August 10, 2006.
- The American Society for Pharmacology and Experimental Therapeutics
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