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P018. The anti-inflammatory cytokine IL-10 is an important mediator of the action of the TLR-9 agonist DIMS0150

C. Admyre, P. von Stein, T. Knittel, O. von Stein, A. Zargari, InDex 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. We have previously shown that DIMS0150 restores the sensitivity of cells to the action of steroids in vitro by monitoring the expression level of steroid response genes such as the CD163 scavenger receptor. To gain further insights into the mechanism of action of DIMS0150 we analyzed whether these sensitizing effects are mediated by the anti-inflammatory cytokine IL-10.

Methods

PBMCs were isolated from buffy coats of patients with ulcerative colitis and moderate to severe disease activity despite steroid treatment. PBMCs were cultured in the presence or absence of dexamethasone, DIMS0150, IL-10 or antibodies directed against the IL-10 receptor. CD163 expression levels were analyzed by cytometric bead array RT-PCR. in cell culture supernatants.

Results

In PBMCs derived from DIMS0150 treatment naive UC patients, CD163 induction by steroids was suppressed compared to healthy controls in vitro. The combined steroid–DIMS0150 treatment in vitro elevated the CD163 expression to the level of healthy controls in a dose dependent manner. The same effect was observed when cells were cultured in the presence of IL-10 but in the absence of DIMS0150 illustrating the known IL-10 steroid sensitizing effect. To elucidate whether the DIMS0150 effect was mediated by IL-10, cells were cultured in the presence of dexamethasone, DIMS0150 and an IL-10 antagonist. In this setting the DIMS0150 sensitizing effect was heavily diminished demonstrating that DIMS0150 mediates its effect through IL-10, which is known to be induced upon DIMS0150 treatment. In accordance with these finding, CD163 levels were restored to the level of healthy controls in PBMCs derived from a UC patient following treatment with a single rectal administration of 30 mg DIMS0150 in vivo.

Conclusion

The effects of TLR-9 activating oligonucleotide DIMS0150 in vitro are mediated by the inflammatory cytokine IL-10. DIMS0150 has shown promising effects in the treatment of patients with ulcerative colitis, which might be mediated through the interleukin-10 pathway in vivo.