Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2023 Jan;22(1):21-37.
doi: 10.1038/s41573-022-00557-6. Epub 2022 Sep 21.

Emerging principles of cytokine pharmacology and therapeutics

Robert A Saxton #  1   2   3 , Caleb R Glassman #  1   2 , K Christopher Garcia  4   5   6
Affiliations
Review

Emerging principles of cytokine pharmacology and therapeutics

Robert A Saxton et al. Nat Rev Drug Discov. 2023 Jan.

Abstract

Cytokines are secreted signalling proteins that play essential roles in the initiation, maintenance and resolution of immune responses. Although the unique ability of cytokines to control immune function has garnered clinical interest in the context of cancer, autoimmunity and infectious disease, the use of cytokine-based therapeutics has been limited. This is due, in part, to the ability of cytokines to act on many cell types and impact diverse biological functions, resulting in dose-limiting toxicity or lack of efficacy. Recent studies combining structural biology, protein engineering and receptor pharmacology have unlocked new insights into the mechanisms of cytokine receptor activation, demonstrating that many aspects of cytokine function are highly tunable. Here, we discuss the pharmacological principles underlying these efforts to overcome cytokine pleiotropy and enhance the therapeutic potential of this important class of signalling molecules.

PubMed Disclaimer

Conflict of interest statement

Competing interests

K.C.G. is the founder of Synthekine Therapeutics. R.A.S., C.R.G. and K.C.G. are inventors on patents relating to molecules discussed in this Review that are being commercialized.

Figures

Fig. 1 |
Fig. 1 |. Mechanism of cytokine signalling and sources of pleiotropy.
a | Model of the two-step activation mechanism common among cytokine receptors, in which the soluble cytokine ligand (yellow) first engages a high-affinity receptor subunit (cyan) via site 1, enabling recruitment of the low-affinity receptor subunit (green) from elsewhere on the cell surface. Formation of the ternary cytokine receptor complex enables the activation and transphosphorylation of the intracellular Janus kinases (JAKs) (green, purple), triggering the phosphorylation and nuclear translocation of the signal transducer and activator of transcription (STAT) transcription factors. b | Many cytokines exhibit functional and/or cellular pleiotropy due to the activation of multiple downstream transcription factors or due to their ability to signal on diverse cell types such as macrophages (cyan), T cells (lilac), B cells (red) or natural killer cells (white). c | Modulation of cytokine receptor affinity at site 1 alters the dose sensitivity (EC50) of STAT activation, whereas modulation of site 2 alters the maximal strength (Emax). Graphs show the extent of STAT phosphorylation (pSTAT) as a function of cytokine concentration.
Fig. 2 |
Fig. 2 |. Tunable parameters in cytokine receptor pharmacology.
a | Model highlighting the three parameters of cytokine receptor signalling that can be controlled through cytokine engineering to influence cytokine function, including receptor affinity, receptor geometry/orientation and receptor subunit composition. b | Cytokine partial agonists, which exhibit a lower signalling maximal strength (Emax) relative to their natural cytokine counterparts, can overcome cytokine pleiotropy by exploiting differential signalling response thresholds across cell populations. For example, interleukin-2 (IL-2) partial agonists can selectively exert immunosuppressive activity by preferentially expanding CD4+ regulatory T cells (Treg cells) (blue) over effector CD8+ T cells or natural killer cells (red). JAK, Janus kinase; pSTAT, signal transducer and activator of transcription (STAT) phosphorylation.
Fig. 3 |
Fig. 3 |. Tuning cytokine function by controlling receptor affinity.
a | Crystal structure of the interleukin-2 (IL-2) receptor complex [PDB:2B5I] showing IL-2 (yellow), IL-2Rα (pink), IL-2Rβ (cyan) and common γ-chain (γc) (green). Protein engineering strategies that increase the affinity of IL-2 for IL-2Rβ yielded super-2, a more potent IL-2 variant with reduced dose sensitivity (EC50). By contrast, reducing the affinity of IL-2 for γc yielded partial agonists, such as H9T, which preferentially polarize CD8+ T cells towards a TCF1+ stem-like state. b | Cryo-electron microscopy structure of the IL-10 receptor complex [PDB:6×93] showing IL-10 (green), IL-10Rα (blue) and IL-10Rβ (purple). Structure-based design of IL-10 variants with reduced affinity for IL-10Rβ yielded myeloid selective variants, such as 10-DE, which suppress pro-inflammatory myeloid activity but no longer stimulate IFNγ production by T cells. c | Cryo-electron microscopy model of the IL-12 receptor complex [EMD:21645] showing IL-12p35 (green), IL-12p40 (yellow), IL-12Rβ1 (blue) and IL-12Rβ2 (purple). Structure-based design of IL-12 variants with reduced affinity for IL-12Rβ1 retains activity on CD8+ effector T cells without stimulating natural killer cell functions. d | Crystal structure of the IL-22 receptor complex [PDB:6WEO] showing IL-22 (cyan), IL-22Rα (purple) and IL-10Rβ (orange). Structure-based design of IL-22 variants with reduced affinity for IL-10Rβ, such as 22-B3, yielded biased agonists that selectively activate STAT3 but not STAT1 or STAT5 in epithelial cells. pSTAT, signal transducer and activator of transcription (STAT) phosphorylation; Treg cells, regulatory T cells; WT, wild type.
Fig. 4 |
Fig. 4 |. Tuning cytokine function by controlling receptor geometry.
a | Crystal structures of the erythropoietin (EPO) receptor (EpoR) in complex with EPO [PDB:1CN4] (left), a diabody [PDB:4Y5Y] (middle) and a homodimeric DARPin [PDB:6MOI] (right). b | Modulation of receptor distance, such as through diabodies, can tune the strength of downstream signal transducer and activator of transcription (STAT) activation. c | Modulation of receptor angle, such as through dimeric DARPins, yields varying degrees of partial agonism which can differentially impact downstream biological functions. pSTAT, STAT phosphorylation.
Fig. 5 |
Fig. 5 |. Nanobody-based surrogate cytokines.
a | Single-domain antibody fragments (nanobodies) can be raised against various distinct epitopes on cytokine receptors, such as IL-2Rβ (cyan) and common γ-chain (γc) (green). b | Nanobodies targeting different cytokine receptors can be paired in a combinatorial manner, providing a panel of potential surrogate cytokines with various receptor binding sites and orientations. c | Different nanobody pairings can elicit distinct signalling profiles, such as varying levels of partial or biased agonism. d | Structural model of a heterodimeric nanobody pairing capable of engaging the interleukin-2 (IL-2) receptor and initiating signal transduction, with IL-2Rβ (cyan), γc (green) and nanobodies (grey and red; respectively [PDB:7S2S] and [PDB:7S2R]). ECD, extracellular domain; JAK, Janus kinase; pSTAT, signal transducer and activator of transcription (STAT) phosphorylation; VHH, variable region of heavy chain only antibody.
Fig. 6 |
Fig. 6 |. Tuning cytokine function by controlling receptor composition.
a | A ‘synthekine’ comprising dominant negative (DN) versions of interleukin-2 (IL-2) (yellow) and IL-4 (purple) linked together through a flexible linker can recruit an unnatural receptor dimer comprising IL-2Rβ (cyan) and IL-4Rα (orange), to elicit a signal transducer and activator of transcription (STAT) activation signal distinct from that of the IL-2 receptor [PDB:2B5I] (left) or the IL-4 receptor [PDB:3BPL] (right) alone. b | Synthekines that pair different cytokine receptor subunits in non-natural combinations can enable the selective activation of a wide range of STAT pairings, theoretically enabling the customized activation of distinct transcriptional programmes. γc, common γ-chain; JAK, Janus kinase.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Akdis M et al. Interleukins, from 1 to 37, and interferon-γ: receptors, functions, and roles in diseases. J. Allergy Clin. Immunol. 127, 701–721.e1–e70 (2011). - PubMed
    1. Rider P, Carmi Y & Cohen I Biologics for targeting inflammatory cytokines, clinical uses, and limitations. Int. J. Cell Biol. 2016, 9259646 (2016). - PMC - PubMed
    1. Donnelly RP, Young HA & Rosenberg AS An overview of cytokines and cytokine antagonists as therapeutic agents. Ann. N. Y. Acad. Sci. 1182, 1–13 (2009). - PMC - PubMed
    1. Pires IS, Hammond PT & Irvine DJ Engineering strategies for immunomodulatory cytokine therapies — challenges and clinical progress. Adv. Ther. 10.1002/adtp.202100035(2021). - DOI - PMC - PubMed
    1. Holder PG et al. Engineering interferons and interleukins for cancer immunotherapy. Adv. Drug Deliv. Rev. 182, 114112 (2022). - PubMed

Publication types