Aptamer-based inhibition of the chemokines CCL17 and CCL22 in allergic and inflammatory reactions

点击翻译按钮获取中文摘要

The CCR4 ligands CCL17 and CCL22 represent well-known biomarkers for atopic diseases. Using mouse models, we demonstrated a major role of CCL17 in the pathogenesis of contact hypersensitivity (CHS), atopic dermatitis, and other inflammatory diseases, whereas CCR4-deficient mice developed enhanced CHS responses. Pharmacological targeting of the CCL17/CCL22-CCR4 axis has been mainly directed towards CCR4 so far, primarily leading to inhibition of regulatory T cells. Remarkably, patients treated with CCR4 neutralizing antibodies often develop skin rashes (Stevens-Johnson Syndrome). Our hypothesis is that CCL17 and CCL22 exert differential functions via CCR4 or other receptors. Therefore, we aim to generate aptamers, which selectively inhibit either of these chemokines. The advantage of aptamers over neutralizing antibodies is their small size, high affinity and the fact that they can be chemically synthesized. So far, we identified a 2’deoxy-2’fluoro RNA (2’-fRNA) aptamer specific for murine CCL17, which efficiently inhibits CHS in vivo, using Systematic Evolution by Exponential Enrichment (SELEX). We now intend to select further RNA- and DNA aptamers, or alternatively clickmers, directed against human and murine CCL17, and against murine CCL22. For DNA aptamers we will perform manual SELEX and for 2’-fRNA aptamers an automated Biomek NX platform will be used. The enrichment of the nucleic acid libraries will be monitored by next-generation sequencing, and individual sequences will be tested for affinity and binding specificity. The inhibitory capacity of aptamers against human CCL17 will be determined in migration assays using the CCR4+ lymphoma line Mac-1 as well as primary human T cells. In parallel, we will optimize the conditions for therapeutic application of aptamers in the CHS model and explore the possibility of epicutaneous application. To unravel the function of CCL22, we generated novel CCL22-deficient and CCL17/CCL22-double deficient mouse strains using designer nucleases. We will assess the development of CHS and T cell migration in these mice in comparison to CCL17- and CCR4-deficient mice. In addition, we will also study the influence of CCL17 and CCL22 on the selection of regulatory T cells.