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Proc Natl Acad Sci U S A. 2018 Aug 28;115(35):8781-8786. doi: 10.1073/pnas.1805288115. Epub 2018 Aug 13.

Interleukin 4 is inactivated via selective disulfide-bond reduction by extracellular thioredoxin.

Author information

1
Department of Chemistry, Stanford University, Stanford, CA 94305.
2
School of Medicine, Stanford University, Stanford, CA 94305.
3
Medical Scientist Training Program, Stanford University, Stanford, CA 94305.
4
Division of Gastroenterology and Hepatology, Department of Medicine, School of Medicine, Stanford University, Stanford, CA 94305.
5
Institute for Immunity, Transplantation and Infection, Stanford University, Stanford, CA 94305.
6
Department of Chemistry, Stanford University, Stanford, CA 94305; khosla@stanford.edu.
7
Department of Chemical Engineering, Stanford University, Stanford, CA 94305.
8
Stanford ChEM-H, Stanford University, Stanford, CA 94305.

Abstract

Thioredoxin 1 (TRX), an essential intracellular redox regulator, is also secreted by mammalian cells. Recently, we showed that TRX activates extracellular transglutaminase 2 via reduction of an allosteric disulfide bond. In an effort to identify other extracellular substrates of TRX, macrophages derived from THP-1 cells were treated with NP161, a small-molecule inhibitor of secreted TRX. NP161 enhanced cytokine outputs of alternatively activated macrophages, suggesting that extracellular TRX regulated the activity of interleukin 4 (IL-4) and/or interleukin 13 (IL-13). To test this hypothesis, the C35S mutant of human TRX was shown to form a mixed disulfide bond with recombinant IL-4 but not IL-13. Kinetic analysis revealed a kcat/KM value of 8.1 μM-1⋅min-1 for TRX-mediated recognition of IL-4, which established this cytokine as the most selective partner of extracellular TRX to date. Mass spectrometry identified the C46-C99 bond of IL-4 as the target of TRX, consistent with the essential role of this disulfide bond in IL-4 activity. To demonstrate the physiological relevance of our biochemical findings, recombinant TRX was shown to attenuate IL-4-dependent proliferation of cultured TF-1 erythroleukemia cells and also to inhibit the progression of chronic pancreatitis in an IL-4-driven mouse model of this disease. By establishing that IL-4 is posttranslationally regulated by TRX-promoted reduction of a disulfide bond, our findings highlight a novel regulatory mechanism of the type 2 immune response that is specific to IL-4 over IL-13.

KEYWORDS:

M2; disulfide bond; interleukin 4; macrophages; thioredoxin

PMID:
30104382
PMCID:
PMC6126747
DOI:
10.1073/pnas.1805288115
[Indexed for MEDLINE]
Free PMC Article

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