15LO1 dictates glutathione redox changes in asthmatic airway epithelium to worsen type 2 inflammation
Tadao Nagasaki, … , Valerian E. Kagan, Sally E. Wenzel
Tadao Nagasaki, … , Valerian E. Kagan, Sally E. Wenzel
Published November 11, 2021
Citation Information: J Clin Invest. 2022;132(1):e151685. https://doi.org/10.1172/JCI151685.
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Research Article Metabolism Pulmonology

15LO1 dictates glutathione redox changes in asthmatic airway epithelium to worsen type 2 inflammation

Abstract

Altered redox biology challenges all cells, with compensatory responses often determining a cell’s fate. When 15 lipoxygenase 1 (15LO1), a lipid-peroxidizing enzyme abundant in asthmatic human airway epithelial cells (HAECs), binds phosphatidylethanolamine-binding protein 1 (PEBP1), hydroperoxy-phospholipids, which drive ferroptotic cell death, are generated. Peroxidases, including glutathione peroxidase 4 (GPX4), metabolize hydroperoxy-phospholipids to hydroxy derivatives to prevent ferroptotic death, but consume reduced glutathione (GSH). The cystine transporter SLC7A11 critically restores/maintains intracellular GSH. We hypothesized that high 15LO1, PEBP1, and GPX4 activity drives abnormal asthmatic redox biology, evidenced by lower bronchoalveolar lavage (BAL) fluid and intraepithelial cell GSH:oxidized GSH (GSSG) ratios, to enhance type 2 (T2) inflammatory responses. GSH, GSSG (enzymatic assays), 15LO1, GPX4, SLC7A11, and T2 biomarkers (Western blot and RNA-Seq) were measured in asthmatic and healthy control (HC) cells and fluids, with siRNA knockdown as appropriate. GSSG was higher and GSH:GSSG lower in asthmatic compared with HC BAL fluid, while intracellular GSH was lower in asthma. In vitro, a T2 cytokine (IL-13) induced 15LO1 generation of hydroperoxy-phospholipids, which lowered intracellular GSH and increased extracellular GSSG. Lowering GSH further by inhibiting SLC7A11 enhanced T2 inflammatory protein expression and ferroptosis. Ex vivo, redox imbalances corresponded to 15LO1 and SLC7A11 expression, T2 biomarkers, and worsened clinical outcomes. Thus, 15LO1 pathway–induced redox biology perturbations worsen T2 inflammation and asthma control, supporting 15LO1 as a therapeutic target.

Authors

Tadao Nagasaki, Alexander J. Schuyler, Jinming Zhao, Svetlana N. Samovich, Kazuhiro Yamada, Yanhan Deng, Scott P. Ginebaugh, Stephanie A. Christenson, Prescott G. Woodruff, John V. Fahy, John B. Trudeau, Detcho Stoyanovsky, Anuradha Ray, Yulia Y. Tyurina, Valerian E. Kagan, Sally E. Wenzel

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Figure 1

Abnormal redox balance, as measured by higher BAL fluid oxidized glutathione (GSSG) and lower intraepithelial cell GSH, is observed in asthmatic BAL fluid, as compared with healthy controls.

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Abnormal redox balance, as measured by higher BAL fluid oxidized glutath...
GSH, GSSG, and the GSH:GSSG ratio were measured by enzymatic assay in bronchoalveolar lavage (BAL) fluid and in fresh epithelial cells from healthy controls (HCs), mild/moderate (M/M), and severe asthma (SA) patients. (A) Higher levels of GSSG and lower GSH:GSSG ratios were observed in asthmatic BAL fluid. (B) Intracellular GSH levels and GSH:GSSG were lower in fresh asthmatic epithelial cells compared with HCs. (C) BAL fluid (n = 98) and intracellular GSH:GSSG (n = 26) positively correlated with FeNO. ANOVA with intergroup comparisons by t test was used for group comparisons. Pearson’s correlations were used for GSH:GSSG versus FeNO. Bonferroni-corrected significant P values for 3 groups was set at 0.0166. All data were log transformed prior to analysis and were converted back to the linear scale for presentation. Bars represent mean and error bars represent SEM. *P < 0.01, **P < 0.001, ***P < 0.0001.