Effect of cellular stress and growth factors on COPD airway smooth muscle redox balance and glucose metabolism

<bold>Background:</bold> COPD airway remodelling entails airway smooth muscle (ASM) layer thickening and is caused by abnormal oxidative stress adaptation and injury repair. Metabolic reprogramming is pivotal in the cellular response to stress and growth factor stimulation. <bold>Aims & Objectives:</bold> Determine whether COPD ASM cells (ASMCs) display distinct mitochondrial and metabolic function, and redox balance, in response to cellular stress and growth factors. <bold>Methods:</bold> ASM cells (ASMCs) from healthy smokers (HS) and COPD patients (n=7/group), were exposed to serum-starvation-induced stress or TGF-β (1ng/ml)/FBS (2.5%; TGF-β/FBS) stimulation for 24-72h. Reactive oxygen species (ROS) were measured by dichlorofluorescein staining, ATP production rate using a Seahorse XFp Analyzer, and mitochondrial morphology by MitoTracker Red staining. Untargeted metabolomics analysis was also performed. <bold>Results:</bold> Serum-starved COPD ASMCs showed metabolic dysfunction including mitochondrial fission, and lower glycolysis-dependent (30%; p=0.004) and total ATP (28%; p=0.009) production. Serum-starved COPD ASMCs, also showed reduced antioxidant gene expression and elevated glutathione metabolites, indicating redox imbalance. TGF-β/FBS-stimulated COPD ASMCs showed greater proliferation (54%; p<0.05), which was more sensitive to inhibition by the glycolysis inhibitor 2-deoxy-D-glucose. TGF-β/FBS reduced ROS (27%; p<0.05) and increased glutathione-mediated antioxidant responses in COPD, but not in HS, cells. <bold>Conclusion:</bold> COPD ASMCs show altered redox and metabolic balance in response to stress and growth factor stimulation, which may lead to aberrant survival and proliferation, and consequently to remodelling.