Interleukin-1 beta (IL-1 beta), also called IL-1F2, is a proinflammatory cytokine that functions in host defense following injury or inflammation (1-5). IL-1 beta is expressed by cells of the immune system such as monocytes, macrophage, neutrophils, and hepatocytes (1-3). Human IL-1 beta protein is expressed in the cytoplasm in an inactive precursor form (pro-IL-1 beta) which is 269 amino acids in length with a theoretical molecular weight of 31 kDa (1,4,6). Pro-IL-1 beta is cleaved by IL-1 converting enzyme (ICE), also called caspase-1, generating the 18 kDa mature, active protein that is secreted from cells (1,4,6). Pro-IL-1 beta is produced as a cellular response to molecular signals from pathogens and other processes termed pathogen associated molecular patterns (PAMPs) and damage associated molecular patterns (DAMPs) (1,2). PAMPs and DAMPs signal through pattern recognition receptors (PRRs) to induce formation of the inflammasome (1,2). The inflammasome is a multi-protein complex made of a PRR, such as Nod-like receptor family, pyrin domain containing 3(NLRP3), an adaptor, such as apoptosis-associated spec-like protein containing a CARD (ASC), and pro-caspase-1 (1-3,5). Assembly of the inflammasome enables cleavage of pro-caspase-1 into active caspase 1, followed by secretion of activate IL-1 beta (1-3,5).
IL-1 beta binding to its receptor IL-1RI and the downstream signaling contributes to a dual pathophysiological role (3). On one hand, IL-1 beta signaling activates immune cells and drives CD4+ T cell polarization to T helper type 1 (Th1) and Th17 cells, resulting in anti-tumor responses and mediation of acute inflammation (2,3). However, IL-1 beta also supports tumor growth and metastasis driven by multiple mechanisms including chronic inflammation, an immunosuppressive tumor microenvironment (TME), and angiogenesis (3). Additionally, IL-1 beta signaling been implicated in the pathogenesis of neuroinflammatory diseases of the central nervous system (CNS) such as multiple sclerosis (MS), Alzheimer's disease, and diabetic retinopathy (DR) (2). Mouse studies have shown regression of tumors treated with IL-1 as well as protective effects of IL-1 beta in instances of induced colitis and colon carcinoma (3). Conversely, blocking IL-1 beta has also shown promising effect in cancer treatment, especially when combined with chemotherapeutics (2,3). Approved IL-1 beta monoclonal antibody canakinumab has shown significant therapeutic promise in the treatment of DR (2). Given its multifaceted role in disease, IL-1 beta is a promising therapeutic target.
1. Lopez-Castejon G, Brough D. Understanding the mechanism of IL-1beta secretion. Cytokine Growth Factor Rev. 2011;22(4):189-195. https://doi.org/10.1016/j.cytogfr.2011.10.001
2. Mendiola AS, Cardona AE. The IL-1beta phenomena in neuroinflammatory diseases. J Neural Transm (Vienna). 2018;125(5):781-795. https://doi.org/10.1007/s00702-017-1732-9
3. Bent R, Moll L, Grabbe S, Bros M. Interleukin-1 Beta-A Friend or Foe in Malignancies?. Int J Mol Sci. 2018;19(8):2155. https://doi.org/doi:10.3390/ijms19082155
4. Krumm B, Xiang Y, Deng J. Structural biology of the IL-1 superfamily: key cytokines in the regulation of immune and inflammatory responses. Protein Sci. 2014;23(5):526-538. https://doi.org/10.1002/pro.2441
5. He Y, Hara H, Nunez G. Mechanism and Regulation of NLRP3 Inflammasome Activation. Trends Biochem Sci. 2016;41(12):1012-1021. https://doi.org/10.1016/j.tibs.2016.09.002
6. Uniprot (P01584)