33 - S-glutathionylation of pyruvate kinase M2 is associated with metabolic reprogramming and cytokine production in the development of allergic obese airway disease

Abstract

Early on-set allergic obese asthma is an important global clinical problem due to the mounting number of patients and their disease severity that is poorly controlled with available therapeutics. Alterations in metabolism and accompanying changes in redox homeostasis are known to contribute to obesity-associated diseases. Protein S-glutathionylation (PSSG) is a redox-based modification of protein cysteines involving the conjugation of glutathione to the reactive thiol group. We have discovered a direct correlation between PSSG chemistry, glycolysis and inflammation in the lungs from mice fed a high fat diet for 15 weeks. Analysis of lung tissue from obese mice identified that the glycolytic enzyme pyruvate kinase M2 (PKM2), known to catalyze the final step in glycolysis, is a target of s-glutathionylation in the lung tissue from obese mice. Furthermore, we have identified that oxidative stress and s-glutathionylation of PKM2 are increased in primary tracheal epithelial cells cultured in high glucose (25 mM) and treated with palmitate compared to MTECs cultured in normal glucose (5.6 mM). The objective of this study was to identify the s-glutathionylated proteome and investigate if s-glutathionylation of PKM2 alters its protein function to enhance inflammation in the lung tissue from mice treated with house dust mite and subjected to diet induced obesity, a model of early on-set allergic obese asthma. Here we show that s-glutathionylation of PKM2 decreases its glycolytic enzyme activity. This correlates with the upregulation of the inflammatory cytokines thymic stromal lymphopoietin (TSLP) and granulocyte-macrophage colony-stimulating factor (GM-CSF), known to contribute to steroid resistance and neutrophil infiltration in the lung during obesity. Treatment of primary mouse tracheal epithelial cells with the PKM2 small molecule activator TEPP46 attenuates mRNA expression and secretion of TSLP and GM-CSF. Overall, these findings suggest that unique redox perturbations and glycolysis may contribute to the enigmatic endotype of allergic obese asthma.