IL-33 induction and signaling are controlled by glutaredoxin-1 in mouse macrophages

• Published in: PloS one 2019-01, Vol.14 (1), p.e0210827-e0210827
• Main Authors: Weinberg, Ellen O, Ferran, Beatriz, Tsukahara, Yuko, Hatch, Michaela M S, Han, Jingyan, Murdoch, Colin E, Matsui, Reiko
• Format: Article
• Language: English
• Subjects: Adducts; Allergens; Allergens - administration & dosage; Animals; Antigens; Asthma; Asthma - etiology; Asthma - immunology; Asthma - metabolism; Biology; Biology and Life Sciences; Cellular signal transduction; Chromatin; Cytokines; Data analysis; Data processing; Disease; Disease Models, Animal; Gene expression; Gene Expression - drug effects; Gene Knockdown Techniques; Gene sequencing; Glutaredoxin; Glutaredoxins - deficiency; Glutaredoxins - genetics; Glutaredoxins - metabolism; Glutathione - metabolism; Hypersensitivity; Immunity; Inflammation; Inhibition; Interleukin; Interleukin 1; Interleukin-33 - biosynthesis; Interleukin-33 - genetics; Interleukins; Laboratory animals; Lipopolysaccharides; Lipopolysaccharides - pharmacology; Lung - immunology; Lung - metabolism; Lungs; Lymphocytes T; Macrophages; Macrophages - drug effects; Macrophages - immunology; Macrophages - metabolism; Medicine; Medicine and Health Sciences; Messenger RNA; Mice; Mice, Knockout; Mucosal immunity; NF-kappa B - metabolism; NF-κB protein; Paracrine signalling; Proteins; RAW 264.7 Cells; Research and Analysis Methods; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Small Interfering - genetics; Rodents; Signal Transduction; siRNA; TNF Receptor-Associated Factor 6 - metabolism; TRAF6 protein
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0210827

Interleukin (IL)-33 is an interleukin-1 like cytokine that enhances Th2 responses and mediates mucosal immunity and allergic inflammation but the mechanism regulating endogenous IL-33 production are still under investigation. In macrophages, lipopolysaccharide (LPS) administration resulted in marked induction of IL-33 mRNA that was blunted in macrophages from glutaredoxin-1 (Glrx) knockout mice and in RAW264.7 macrophages with Glrx knockdown by siRNA. Glutaredoxin-1 is a small cytosolic thioltransferase that controls a reversible protein thiol modification, S-glutationylation (protein-GSH adducts), thereby regulating redox signaling. In this study, we examined the mechanism of Glrx regulation of endogenous IL-33 induction in macrophages. Glrx knockdown resulted in impaired de-glutathionylation of TRAF6, which is required for TRAF6 activation, and inhibited downstream IKKβ and NF-κB activation. Inhibitors of NF-κB suppressed IL-33 induction and chromatin IP sequencing data analysis confirmed that IL-33 is an NF-κB-responsive gene. Since TRAF6-NF-κB activation is also essential for IL-33 signaling through its receptor, ST2L, we next tested the involvement of Glrx in exogenous IL-33 responses in RAW264.7 cells. Recombinant IL-33 (rIL-33) administration induced IL-33 mRNA expression in RAW264.7 macrophages, and this was inhibited by Glrx knockdown. Interestingly, rIL-33-induced IL-33 protein was identified as the 20 kDa cleaved form whereas LPS-induced IL-33 protein was identified as full-length IL-33, which may be less active than the cleaved form. In a clinically-relevant mouse model of asthma, intra-tracheal cockroach antigen treatment induced Glrx protein in wild type mouse lungs but Glrx induction was attenuated in IL-33 knockout mouse lungs, suggesting that IL-33 may regulate Glrx induction in vivo in response to allergen challenge. In summary, our data reveal a novel mechanism by which Glrx controls both LPS- and IL-33-mediated NF-κB activation leading to IL-33 production, and paracrine IL-33 can induce Glrx to further regulate inflammatory reactions.