Recombinant human IL-12 protein - Bioactive cytokine

Interleukin 12 background

Interleukin 12 (IL-12), also known as IL-12p70, cytotoxic lymphocyte maturation factor (CLMF), or natural killer cell stimulatory factor (NKSF) is the founding member of the heterodimeric IL-12 cytokine family. This family is characterized by the sharing of p19, p28, p35, p40, and Ebi3 subunits, and includes IL-12, IL-23, IL-27, IL-35, and IL-39 [1, 2]. The secretion of bioactive IL-12 requires the co-expression of IL-12p35 and IL-12p40 and disulfide bond formation. IL-12 is primarily produced by pathogen-activated macrophages and dendritic cells (DC) [1, 2].

The binding of IL-12 to its IL-12Rβ1/IL-12Rβ2 heterodimeric receptor triggers a JAK2/TYK2 signal transduction leading to the activation of STAT4. Activated STAT4 forms homodimers that are translocated to the nucleus where they regulate the expression of target genes. Subsequent gene expression promotes the cytotoxic activity of Natural Killer (NK) and CD8+ T cells, and drives IFN-γ production by NK and activated CD4+ T cells [1, 2]. IFN-γ contributes to the differentiation of Th1 cells and inhibits Th2 cell development. Moreover, it enhances DC maturation and antigen presentation.

Interestingly, secreted IL-12p40 monomers and homodimers (IL-12p80) have also been found and described to function as IL-12 antagonists or agonists, depending on the experimental studies [2].

Relevance for therapeutics development

IL-12 is a key cytokine for controlling intracellular infections. However, excessive IL-12 production contributes to several immune-mediated inflammation diseases including rheumatoid arthritis, type I diabetes, multiple sclerosis, and Crohn's disease [1].

Ustekinumab is a fully human monoclonal antibody (mAb) that targets the p40 subunit common to IL-12 and IL-23, preventing their interactions with their receptor common chain IL-12Rβ1 [3]. This antibody is FDA-approved for treating psoriasis, psoriatic arthritis, Crohn's disease, and ulcerative colitis [4]. Addressing the benefits of neutralizing IL-12 and IL-23 together or individually, depending on the clinical context can be achieved using neutralizing mAbs targeting the p19 subunit of IL-23 [5].

As IL-12 drives strong pro-inflammatory and cytotoxic activities, a series of IL-12-based products have been explored for cancer therapy. These strategies must control targeted delivery to achieve high local IL-12 while avoiding systemic toxicity [6-8].

References:

1. Dembic., Z., 2015. Chapter 6 - Cytokines of the immune system: Interleukins. The cytokines of the immune system (book): 143-239.
2. Floss, D.M., et al., 2020. IL-12 and IL-23-Close Relatives with Structural Homologies but Distinct Immunological Functions. Cells, 9(10): 2184.
3. Benson, J.M, et al., 2011. Discovery and mechanism of ustekinumab: a human monoclonal antibody targeting interleukin-12 and interleukin-23 for treatment of immune-mediated disorders. MAbs 3(6):535-545.
4. FDA website accessed in Nov 2024: https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/761044s013lbl.pdf#page=37
5. Tait Wojno, E.D. et al., 2019. The Immunobiology of the Interleukin-12 Family: Room for Discovery. Immunity. 50(4):851-870.
6. Leonard, W.J. & Lin, J. X., 2023. Strategies to therapeutically modulate cytokine action. Nat Rev Drug Discov. 22(10):827-584.
7. Briukhovetska D., et al., 2021. Interleukins in cancer: from biology to therapy. Nat Rev Cancer. 21(8):481-499.
8. Yi, M., et al., 2024. Targeting cytokine and chemokine signaling pâthways for cancer therapy. Signal Transduction and Targeted Therapy. 9(1):176.