Abstract Chemerin, a ligand for seven-pass transmembrane, G protein-associated receptor CMKLR1 requires C-terminal proteolytic processing to unleash its chemoattractant activity. Proteolytically-processed chemerin selectively attracts specific subsets of immunoregulatory antigen presenting cells, such as immature plasmacytoid dendritic cells (pDC) and macrophages that express CMKLR1. Chemerin is predicted to belong to the structural cathelicidin/cystatin family of proteins that comprise inhibitors of cysteine proteinases (cystatins). Cysteine proteinases of the papain-like family are well characterized proteolytic enzymes, best known for their role in intracellular proteolytic pathways. Nevertheless, recent studies show that lysosomal cathepsins can also exert their proteolytic activity at extracellular sites in secreted or cell surface-bound forms. Extracellular cathepsins contribute to a variety of pathophysiological processes, including inflammation and neoplastic progression. Homology between chemerin and cystatins suggests that chemerin interacts directly with cysteine proteases. In this work, we demonstrate that chemerin does not display substantial inhibitory activity against human cysteine proteases. Instead, chemerin was found to be a new substrate for these proteases. The interaction between chemerin and the proteases resulted in the generation of potent attractant activity, eliciting a robust chemotactic response by CMKLR1 transfectants as well as human blood-derived PDC. Our data demonstrate that cathepsins may contribute to immune responses through the recruitment of pDC.
Chemerin, a ligand for the G-protein coupled receptor chemokine-like receptor 1, requires C-terminal proteolytic processing to unleash its chemoattractant activity. Proteolytically processed chemerin selectively attracts specific subsets of immunoregulatory APCs, including chemokine-like receptor 1-positive immature plasmacytoid dendritic cells (pDC). Chemerin is predicted to belong to the structural cathelicidin/cystatin family of proteins composed of antibacterial polypeptide cathelicidins and inhibitors of cysteine proteinases (cystatins). We therefore hypothesized that chemerin may interact directly with cysteine proteases, and that it might also function as an antibacterial agent. In this article, we show that chemerin does not inhibit human cysteine proteases, but rather is a new substrate for cathepsin (cat) K and L. cat K- and L-cleaved chemerin triggered robust migration of human blood-derived pDC ex vivo. Furthermore, cat K- and L-truncated chemerin also displayed antibacterial activity against Enterobacteriaceae. Cathepsins may therefore contribute to host defense by activating chemerin to directly inhibit bacterial growth and to recruit pDC to sites of infection.
Reported here is the characterization of cenerimod, a novel, potent, selective, and orally active sphingosine-1-phosphate receptor 1 (S1P1) modulator in the context of SLE.
Methods
Lymphocytes from patients with SLE and healthy subjects were assessed for cenerimod-induced S1P1 receptor internalization. Efficacy of cenerimod was evaluated in the MRL/lpr lupus mouse model. In a 12-week phase 2 clinical trial in SLE subjects treated with multiple doses of cenerimod (NCT02472795), lymphocyte subsets and inflammatory biomarkers were characterized.
Results
Cenerimod was potent and efficacious at inducing S1P1 receptor internalization in T and B lymphocytes with an EC50 of ∼15 nM in both healthy subjects and patients with SLE. In lupus-like MRL/lpr mice treated with cenerimod, circulating T and B lymphocytes were reduced, which resulted in reduced immune infiltrates into tissue, reduced autoantibody production and inflammation, preserved organ function, and increased survival. In SLE subjects treated with cenerimod for 12 weeks, a dose-dependent reduction of circulating T cells (95%), B cells (90%), and antibody-secreting cells (85%) was evident. Furthermore, a reduction in anti-dsDNA antibodies and IFN-α, two key inflammatory molecules, was observed.
Conclusion
Cenerimod was potent and efficacious in reducing S1P1 receptor surface expression on lymphocytes, resulting in reduced circulating T and B lymphocyte populations, including antibody-secreting cells, and a decrease in inflammatory biomarkers in SLE subjects. Furthermore, cenerimod significantly ameliorated systemic and organ-specific autoimmunity in a mouse model of SLE. These results warranted the further investigation of the clinical efficacy and safety of cenerimod in the ongoing phase 2b clinical trial (NCT03742037).
Acknowledgments
This research was funded by Idorsia Pharmaceuticals Ltd.
Abstract Neutralization of the common p40-subunit of IL-12/23 in psoriasis patients has led to a breakthrough in the management of moderate to severe disease. Aside from neutralizing IL-23, which is thought to be responsible for the curative effect, anti-p40 therapy also interferes with IL-12 signalling and type 1 immunity. Here we dissect the individual contribution of these two cytokines to the formation of psoriatic lesions and understand the effect of therapeutic co-targeting of IL-12 and IL-23 in psoriasis. Using a preclinical model for psoriatic plaque formation we show that IL-12, in contrast to IL-23, has a regulatory function by restraining the invasion of an IL-17-committed γδT (γδT17) cell subset. We discover that IL-12 receptor signalling in keratinocytes initiates a protective transcriptional programme that limits skin inflammation, suggesting that collateral targeting of IL-12 by anti-p40 monoclonal antibodies is counterproductive in the therapy of psoriasis.
