Characteristics and Functions of IL-37

Abstract

Interleukin-37 (IL-37), previously known as IL-1F7, is a member of the IL-1 family of cytokines. There are five basic subtypes of IL-37, including IL-37a, IL-37b, IL-37c, IL-37d, and IL-37e. Like other members of the IL-1 family, IL-37 is initially expressed as an immature precursor protein that needs to be processed enzymatically by caspase-1 to generate the bioactive protein. However, unlike most other members of the IL-1 family, IL-37 induces anti-inflammatory activities in IL-37 receptor-positive target cells. IL-37 functions as an extracellular protein by binding to the IL-18 receptor, IL-18R, and an intracellular protein via its interaction with SMAD family member-3 (SMAD-3). This article reviews recent findings regarding the IL-37 protein maturation process and the biological functions mediated by this cytokine.