Background Interleukin (IL)-17 is a pro-inflammatory cytokine produced by various types of cells including CD4 T cells which are categorized as a new subset called Th17 cells. The anti-IL-17A antibodies showed the effectiveness in a clinical trial for rheumatoid arthritis and psoriasis. We have discovered new pyrazole-anilide derivatives (compound A, B and C) which inhibited IL-17 production from mouse CD4 T cells.
Objectives We examined the effect of compounds on production of IL-17 and pro-inflammatory cytokines from mouse and human T cells. Furthermore, we evaluated the effect of compounds on autoimmune disease models in mice.
Methods In vitro: Mouse and human peripheral blood mononuclear cells (PBMCs) were stimulated with anti-CD3 antibody for 72h. The concentration of pro-inflammatory cytokines in the culture supernatants was determined by BD™ Cytometric Beads Array. In vivo: Type II collagen-induced arthritis (CIA) was induced by immunization with an emulsion of bovine type II collagen (CII) and Freund's complete adjuvant (FCA) to the tail base of DBA/1J mice. For psoriasis-like dermatitis, imiquimod (IMQ) was topically applied to the ear of C57BL/6 mice every day for 8 days.
Results Compound A, B and C have a potent inhibitory activity for IL-17 production in antigen- specific mouse memory CD4 T cells and mouse Th17 cells. Moreover, compound B significantly inhibited IL-17 production from mouse and human PBMCs by anti-CD3 antibody stimulation with IC50 value of 600 and 2897 nM, respectively. In mouse CIA, the prophylactic treatment with compound A at 1 to 10 mg/kg showed a significant and dose-dependent inhibitory effect on arthritis score and joint destruction. When compound B and tofacitinib (CP-690,550) were therapeutically administered to mice with established CIA, the progression of arthritis were significantly inhibited by treatment of compound B or CP-690,550 and the inhibitory effect of compound B was comparable with that of the CP-690,550. In this study, a treatment of CP-690,550 decreased the number of NK cells in peripheral blood, however compound B did not affect NK cell counts. The mRNA expression level of IL-17 was markedly elevated in mouse hind paws accompanying with the development of CIA. By contrast, the mRNA expression level of IL-17 was significantly lower in groups given compound B as compared with a control group. Draining lymph node -T cells from CIA mice produced a significant amount of IL-17 by stimulation of CII. Compound B significantly inhibited this IL-17 production. Moreover, in the IMQ-induced psoriasis-like dermatitis, oral administration of compound C (3 and 10 mg/kg) inhibited an increase of the ear thickness. The inhibitory effect of compound C on IMQ-induced dermatitis was comparable with that of anti-mouse IL-17 antibody (200 μg/mouse).
Conclusions The new pyrazole-anilide derivatives ameliorated CIA and psoriasis-like dermatitis in mice. These compounds decreased the IL-17 mRNA expression level in hind paws of CIA mice and inhibited the antigen-induced IL-17 production from CII specific-T cells. Moreover, these compounds inhibited the IL-17 production from human T cells stimulated with anti-CD3 antibody. These results suggest that these compounds have a potential therapeutic efficacy for rheumatoid arthritis and psoriasis.
Disclosure of Interest None declared