We demonstrate that the mechanism of redox remodeling during mouse T cell activation involves secretion of glutathione by dendritic cells and its subsequent cleavage to cysteine. Extracellular cysteine accumulation results in a lower redox potential, which is conducive to proliferation, and changes the net redox status of exofacial protein domains. Regulatory T cells inhibit this redox metabolite-signaling pathway, which represents a previously unrecognized mechanism for immunosuppression of effector T cells.

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Caveolin-1 is a scaffolding/regulatory protein that interacts with diverse signaling molecules. Caveolin-1null mice have marked metabolic abnormalities, yet the underlying molecular mechanisms are incompletely understood. We found the redox stress plasma biomarker plasma 8-isoprostane was elevated in caveolin-1null mice, and discovered that siRNA-mediated caveolin-1 knockdown in endothelial cells promoted significant increases in intracellular H2O2. Mitochondrial ROS production was increased in endothelial cells after caveolin-1 knockdown; 2-deoxy-D-glucose attenuated this increase, implicating caveolin-1 in control of glycolytic pathways. We performed unbiased metabolomic characterizations of endothelial cell lysates following caveolin-1 knockdown, and discovered strikingly increased levels (up to 30-fold) of cellular dipeptides, consistent with autophagy activation. Metabolomic analyses revealed that caveolin-1 knockdown led to a decrease in glycolytic intermediates, accompanied by an increase in fatty acids, suggesting a metabolic switch. Taken together, these results establish that caveolin-1 plays a central role in regulation of oxidative stress, metabolic switching, and autophagy in the endothelium, and may represent a critical target in cardiovascular diseases.