Signalling of multiple interleukin (IL)-17 family cytokines via IL-17 receptor A drives psoriasis-related inflammatory pathways.

BACKGROUND: The interleukin (IL)-23/IL-17 immune axis is of central importance in psoriasis. However, the impact of IL-17 family cytokines other than IL-17A in psoriasis has not been fully established. OBJECTIVES: To elucidate the contribution of IL-17 family cytokines in psoriasis. METHODS: To address the expression and localization of IL-17 family cytokines, lesional and nonlesional skin samples from patients with psoriasis were analysed by several complementary methods, including quantitative polymerase chain reaction, immunoassays, in situ hybridization and immunohistochemistry. Mechanistic studies assessing the functional activity of IL-17 family cytokines were performed using ex vivo cultured human skin biopsies and primary human keratinocytes. RESULTS: We demonstrated that IL-17A, IL-17F, IL-17A/F and IL-17C are expressed at increased levels in psoriasis lesional skin and induce overlapping gene expression responses in ex vivo cultured human skin that correlate with the transcriptomic signature of psoriasis skin. Furthermore, we showed that brodalumab, in contrast to ixekizumab, normalizes gene expression responses induced by the combination of IL-17A, IL-17F, IL-17A/F and IL-17C in human keratinocytes. CONCLUSIONS: Several IL-17 ligands signalling through IL-17RA are overexpressed in psoriasis skin and induce similar psoriasis-related inflammatory pathways demonstrating their relevance in relation to therapeutic intervention in psoriasis.

Rapid-onset clinical and mechanistic effects of anti-C5aR treatment in the mouse collagen-induced arthritis model.

Preclinical evidence supports targeting the C5a receptor (C5aR) in rheumatoid arthritis (RA). To support ongoing clinical development of an anti-C5aR monoclonal antibody, we have investigated for the first time the mechanism of action and the pharmacodynamics of a blocking anti-murine C5aR (anti-mC5aR) surrogate antibody in mouse collagen-induced arthritis (CIA). First, efficacy was demonstrated in a multiple-dose treatment study. Almost complete inhibition of clinical disease progression was obtained, including reduced bone and cartilage destruction in anti-mC5aR-treated mice. Then, the mechanism of action was examined by looking for early effects of anti-mC5aR treatment in single-dose treatment studies. We found that 48 h after single-dose treatment with anti-mC5aR, the neutrophil and macrophage infiltration into the paws was already reduced. In addition, several inflammatory markers, including tumour necrosis factor (TNF)-α, interleukin (IL)-6 and IL-17A were reduced locally in the paws, indicating reduction of local inflammation. Furthermore, dose-setting experiments supported a beneficial clinical effect of dosing above the C5aR saturation level. In conclusion, these preclinical data demonstrated rapid onset effects of antibody blockade of C5aR. The data have translational value in supporting the Novo Nordisk clinical trials of an anti-C5aR antibody in rheumatoid arthritis patients, by identifying potential biomarkers of treatment effects as well as by providing information on pharmacodynamics and novel insights into the mechanism of action of monoclonal antibody blockade of C5aR.