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P018. Successful treatment of acute TNBS-mediated colitis in mice by selective glucocorticoid receptor agonists (SEGRAs) – anti-inflammatory effects and improved safety profile

K.C. Reuter1, C.R. Grunwitz1, B.M. Kaminski1, D. Steinhilber1, H.H. Radeke2, J. Stein1,3

1Goethe University Frankfurt, Institute for Pharmaceutical Chemistry, Frankfurt/Main, Germany; 2Pharmazentrum Frankfurt, Institute for Pharmacology and Toxicology, Goethe-University hospital, Frankfurt/Main, Germany; 3Katharina-Kasper Kliniken, Internal Medicine, Frankfurt/Main, Germany

Background and Aims: Glucocorticoids (GCs) are highly effective in therapy of inflammatory bowel disease (IBD). Their value, however, is limited by several severe and sometimes irreversible side effects. Insights in the molecular mechanisms of the Glucocorticoid receptor (GR) and the finding that activation and repression of gene expression is separable opened the possibility of achieving improved safety profiles by the identification of ligands, which predominantly induce repression, counting for GR's beneficial anti-inflammatory action, instead of activation, associated with side effects. Here we report on Compound A (CpdA) and ZK216348, two new non-steroidal GR-selective agonists for the treatment of experimental colitis.

Material and Methods: A rectal enema of TNBS/Ethanol [100 mg/kg bwt] was applied to male 6–8 weeks old BALB/c mice. CpdA [1, 10 mg/kg bwt] or Dex [1 mg/kg bwt] as treatment control, were administered i.p., ZK216348 [1, 10 mg/kg bwt] s.c, from days 0–3. Assessment of colitis severity was performed daily. Clinical activity, morphological and histopathological changes, colonic levels of myeloperoxidase (MPO by colorimetric assay), pro-inflammatory mediators (TNF-α, IL-1β, COX-2 by qPCR, NF-κB by Western Blot) and the exclusively trans-activated gene of liver tyrosine amino transferase (TAT by qPCR and enzymatic assay) were evaluated 3 days post-TNBS. Influences on Th1-mediated immune response was investigated in ex vivo stimulated CD4+ T-cells from mesenteric lymph nodes by ELISA-technique. For assessment of diabetogenic effects of substances, mice were tested for blood glucose levels, liver glycogen content and for key gluconeogenic enzymes (PEPCK and G-6-P) by colorimetric assay and qPCR, respectively. Apoptosis studies were carried out in PBMCs by FACS analysis and TUNEL-assay in histological sections.

Results: Similar to Dex, treatment with CpdA, at least low dose, and ZK216348 prominently reduced the clinical and histopathological severity of TNBS-induced colitis, abrogating body weight loss, diarrhea and macroscopic and microscopic intestinal inflammation. It could be shown that SEGRAs positively affected the TNBS induced Th1-mediated immune response. The therapeutic effects of the SEGRAs were associated with a down-modulation of MPO activity and pro-inflammatory cytokines (TNF-α, IL-1β) and COX-2, but in contrast to Dex, less induction of blood glucose, glycogen and key gluconeogenic enzymes PEPCK and G-6-P. In addition, CpdA and ZK216348 exhibited less trans-activating properties in regard to hepatic tyrosine aminotransferase (TAT) activity and mRNA expression.

Conclusion: The SEGRAs CpdA and ZK216348 are potent anti-inflammatory agents with a lower potential for side effects, compared with classical Glucocorticoids. They represent promising drug candidates and might display a potent therapeutic instrument for the treatment of IBD.