Linker minimization and characterization of Fc-fused interleukin-17A for increased in vivo half-life.

Interleukin-17A (IL-17A) is a cytokine involved in pro-inflammatory responses and tissue regeneration, with potential therapeutic and research applications. However, its short serum half-life limits in vivo use. Here, we report the systematic design of fc-IL-17A fusion proteins for extended half-life. Through computational analysis of 25 design variants using AlphaFold, we found that IL-17A's native N-terminal unstructured region functions as a crucial natural linker that cannot be effectively replaced by artificial sequences. We therefore generated mouse and human fc-IL-17A variants using direct N-terminal fusion without additional linkers. The resulting proteins retain IL-17A's ability to stimulate IL-6 production and erythroid cell growth. Pharmacokinetic analysis confirms that the Fc fusion increases the serum half-life in mice from 1.5 to 13 hours post-subcutaneous injection. This enables tractable experimental use of IL-17A in vivo for studying its role in inflammation and tissue repair. We further perform pharmacokinetics and pharmacodynamics modeling and propose a dosing regimen with reduced frequency of injection for delivering comparable IL-17A activity. This work provides a valuable pharmacological tool for injectable delivery, enabling investigation of IL-17A's biological functions in homeostasis and disease and exploration of its therapeutic potential in tissue regeneration.