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DOP004. Induction of IL-10 positive cells in the colon mucosa of ulcerative colitis patients by the TLR-9 agonist DIMS0150

U. Billmeier1, C. Admyre2, T. Knittel2, A. Zargari2, M. Neurath1, R. Atreya1, 1University of Erlangen-Nuremberg, Medical clinic 1, Erlangen, Germany, 2InDex Pharmaceuticals AB, R&D Department, Stockholm, Sweden

Background

DIMS0150 is an oligonucleotide that acts as a Toll like receptor 9 (TLR-9) agonist and has shown positive effects on response and remission rates in treatment refractory patients with ulcerative colitis. DIMS0150 induces a variety of anti-inflammatory cytokines including IL-10 in in vitro cultured PBMCs. To gain further insights into the mechanism of action in vivo we analyzed the presence of IL-10 positive lamina propria mononuclear cells in colon biopsies taken at different time points after local application of DIMS0150 in ulcerative colitis patients.

Methods

A randomized, double-blind, multicenter phase II trial was conducted with DIMS0150 in steroid refractory patients with ulcerative colitis of moderate degree (EudraCT number: 2006–001846–15). Patients were randomized to a single rectal administration of either 30 mg of DIMS0150 or placebo. Clinical response (DAI score decrease of at least 3 points from baseline) at week 1 and 4 was 41.2% and 52.9% in the DIMS0150 and 9.1% and 36.4% in the placebo treated group.

Cross-sections from colon biopsies of ulcerative colitis patients taken 28 days after DIMS0150 (n = 14) or placebo treatment (n = 4) were stained for IL-10. Immunofluorescence microscopy subsequently allowed quantification of IL-10 positive intestinal immune cells. Number of IL-10 positive mucosal immune cells among a total of 300 counted cells was blindly analyzed in each probe. Similar stainings were additionally performed at day 7 after DIMS0150 (n = 10) and placebo (n = 7) treatment.

Results

Analysis of IL-10 expression in colonic biopsies at day 28 after DIMS0150 treatment interestingly indicated a significantly increased number of IL-10 positive lamina propria immune cells (mean 108/300 positive cells; SEM ±28.9) compared to placebo treated patients (mean 67/300 positive cells; SEM ±10.8) (p = 0.02).

Additionally performed analysis at day 7 implicated that the observed up-regulation of IL-10 in colon infiltrating immune cells is an early occurring and direct effect of locally applied DIMS0150 (mean of 114/300 IL-10 positive cells; SEM ±34.2 in DIMS0150 versus 70/300 IL-10 positive cells ±10.2 in placebo treated patients).

Conclusion

DIMS0150 has shown promising effects in the treatment of patients with ulcerative colitis. Analysis of histological cross sections revealed for the first time in vivo a significantly higher expression of the cytokine IL-10 in the gut mucosa of ulcerative colitis patients who received the TLR9 agonist DIMS0150 in comparison to placebo-treated patients. Thus, regarding the mechanism of action the anti-inflammatory cytokine IL-10 could be the key mediator of the therapeutic effect of the late stage clinical candidate DIMS0150 in ulcerative colitis patients.