Interleukin 17 (IL-17) and its cognate receptor (IL-17RA)1 play a crucial role in Th17 cells-mediated pro-inflammatory pathway and pathogenesis of several autoimmune disorders including psoriasis. Psoriasis is a chronic inflammatory skin disease with prevalence up to 3% worldwide it is characterized by hyperplasia of the epidermis, infiltration of leukocytes into both dermis and epidermis, and dilation and growth of blood vessels. IL-17 is mainly produced by Th-17 helper cells and, via binding to its receptor, mediates IL-17-driven cell signaling in keratinocytes2.
This work was aimed to generate a novel protein binders of IL-17RA that will prevent from binding of IL-17 to this receptor expressed on the surface of keratinocytes. To this goal, we used a high-complex combinatorial library derived from a scaffold of albumin-binding domain (ABD) of streptococcal protein G3, and ribosome display selection, to yield a collection of ABD-derived high-affinity ligands of human IL-17RA, called ARS binders. From 67 analysed ABD variants, 7 different sequence families were identified. Representatives of these groups competed with human IL-17A for binding to recombinant IL-17RA receptor as well as with IL-17RA-IgG chimera, as tested in ELISA. Five ARS variants bind to IL-17RA-expressing THP-1 and Raji cells, as tested by flow cytometry, and four variants exhibited high-affinity binding in nanomolar range to human keratinocyte HaCAT cells, as measured using LigandTracer Green Line system. Thus, we identified several ARS inhibitory variants with a blocking potential that will be further tested for their immunomodulatory function.
This study was supported by the Grant BIOCEV CZ.1.05/1.1.00/02.0109 from the ERDF fund and Institutional Research Concept No. RVO 86652036.