Pharmacological enhancement of O-GlcNAcylation attenuates lung ischemia-reperfusion injury

Lung ischemia-reperfusion injury (LIRI) contributes substantially to primary graft dysfunction after lung transplantation and also occurs in other clinical settings involving transient interruption and restoration of pulmonary blood flow. O-linked β-N-acetylglucosamine (O-GlcNAc) modification is rapidly altered by cellular stress, yet its role in acute pulmonary ischemia-reperfusion remains incompletely understood. We investigated this question using a murine model of transient left pulmonary hilar occlusion followed by reperfusion and an oxygen-glucose deprivation/reoxygenation (OGD/R) model in MLE-12 cells. O-GlcNAcylation was increased pharmacologically with the O-GlcNAcase inhibitor Thiamet G and reduced with the O-GlcNAc transferase inhibitor OSMI-4. Global O-GlcNAc levels, indices of tissue and cellular injury, and Caspase-1/GSDMD-related pyroptotic signaling were then examined. In both models, O-GlcNAcylation increased early after ischemic stress, whereas pyroptosis-related changes became more pronounced as injury progressed. Thiamet G preserved MLE-12 cell viability, reduced LDH release, and lessened histopathological damage, pulmonary edema, and alveolar-capillary protein leakage in vivo. These effects were accompanied by lower Caspase-1 activation, reduced GSDMD cleavage, and fewer Caspase-1/PI double-positive cells. OSMI-4 produced the opposite pattern, with greater tissue and cellular injury and stronger pyroptosis-related signaling. The protective effect of Thiamet G was also weakened when OSMI-4 was given concurrently. These findings indicate that the early rise in O-GlcNAcylation is consistent with an acute stress response to LIRI. Pharmacologically maintaining higher O-GlcNAcylation was associated with less severe injury and weaker Caspase-1/GSDMD-related signaling, supporting further investigation of this modification as a therapeutic target in acute LIRI.