- Bloch Y, Bouchareychas L, Merceron R, Skladanowska K, Van den Bossche L, Detry S, Govindarajan S, Elewaut D, Haerynck F, Dullaers M, Adamopoulos IE, Savvides SN
- Structural Activation of Pro-inflammatory Human Cytokine IL-23 by Cognate IL-23 Receptor Enables Recruitment of the Shared Receptor IL-12Rbeta1.
- Immunity. 2017 Dec 21. pii: S1074-7613(17)30537-X. doi:, 10.1016/j.immuni.2017.12.008.
- Interleukin-23 (IL-23), an IL-12 family cytokine, plays pivotal roles in pro-inflammatory T helper 17 cell responses linked to autoimmune and inflammatory diseases. Despite intense therapeutic targeting, structural and mechanistic insights into receptor complexes mediated by IL-23, and by IL-12 family members in general, have remained elusive. We determined a crystal structure of human IL-23 in complex with its cognate receptor, IL-23R, and revealed that IL-23R bound to IL-23 exclusively via its N-terminal immunoglobulin domain. The structural and functional hotspot of this interaction partially restructured the helical IL-23p19 subunit of IL-23 and restrained its IL-12p40 subunit to cooperatively bind the shared receptor IL-12Rbeta1 with high affinity. Together with structural insights from the interaction of IL-23 with the inhibitory antibody briakinumab and by leveraging additional IL-23:antibody complexes, we propose a mechanistic paradigm for IL-23 and IL-12 whereby cognate receptor binding to the helical cytokine subunits primes recruitment of the shared receptors via the IL-12p40 subunit.