Objective: To discover a novel peptoid antagonist that targets the interleukin-15 (IL-15) receptor and to evaluate its therapeutic efficacy in the treatment of inflammation and arthritis.
Methods: A new compound (IFRA3, interleukin-15 receptor antagonist 3) was discovered using a unique on-bead two-colour combinatorial cell screening of a peptoid library. The interaction of IFRA3 with IL-15 receptor was assessed by in vitro pull-down and thermal shift assays. The efficacy of IFRA3 in treating inflammation and arthritis was evaluated in mouse models.
Results: IFRA3Q1 (a tetrameric derivative of IFRA3) inhibited the activity of IL-15 and suppressed CTLL-2 cell proliferation (which depends on IL-15 activity). IFRA3Q1 exhibited strong in vivo anti-inflammatory activity in carrageenan-induced inflammation in mice. Furthermore, IFRA3Q1 inhibited collagen-induced arthritis in DBA/1J mice.
Conclusion: By binding to and inhibiting the function of IL-15 receptor, IFRA3Q1 exhibited significant anti-arthritis activity. Our findings suggest that IFRA3Q1 represents a new paradigm for arthritis therapy by targeting IL-15 signalling.
Keywords: inflammation; interleukin‐15; peptoid; rheumatoid arthritis.
© 2022 The Authors. Clinical & Translational Immunology published by John Wiley & Sons Australia, Ltd, on behalf of Australian and New Zealand Society for Immunology, Inc.