Interleukins (IL) are immunomodulatory proteins that elicit a wide array of responses in cells and tissues. Interleukin 37 (IL-37, IL-1 F7) is a member of the IL-1 family. There are five isoforms of IL-37 (a-e) of which transcript IL-37b is known to be functional (Sharma et al. 2008). This isoform is represented in UniProt as the canonical form of IL-37 and in Reactome as the full length, unprocessed form of IL-37. Like several other IL-1 family members, IL-37 is synthesized as a precursor that requires processing (primarily by caspase 1) to attain full receptor agonist or antagonist function. (Kumar et al. 2002). IL-18 binding protein (IL-18BP) binds IL-18 with high affinity inhibiting its activity (Kim et al. 2000). Both full length and processed IL-37 bind the third extracellular domain (D3) of IL-18BP. The binding of IL-18BP to IL-37 makes it unavailable for neutralization of IL-18 activity (Bufler et al. 2002). These events ultimately lead to suppression of cytokine production in several types of immune cells resulting in reduced inflammation.
Dinarello, CA, Bufler, P, Kim, SH, Azam, T, Kumar, S, Gamboni-Robertson, F, Reznikov, LL
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