Abstract
The effects of acute hyperglycemia on lung ischemia-reperfusion (IR) injury and the role of receptor for advanced glycation end-products (RAGE) signaling in this process are unknown. The objective of this study was twofold: (1) evaluate the impact of acute hyperglycemia on lung IR injury; and (2) determine if RAGE signaling is a mechanism of hyperglycemia-enhanced IR injury. We hypothesized that acute hyperglycemia worsens lung IR injury through a RAGE signaling mechanism. C57BL/6 wild-type (WT) and RAGE knockout (RAGE (-/-)) mice underwent sham thoracotomy or lung IR (1-h left hilar occlusion and 2-h reperfusion). Acute hyperglycemia was established by dextrose injection 30 minutes before ischemia. Lung injury was assessed by measuring lung function, cytokine expression in bronchoalveolar lavage fluid, leukocyte infiltration, and microvascular permeability via Evans blue dye. Mean blood glucose levels doubled in hyperglycemic mice 30 minutes after dextrose injection. Compared with IR in normoglycemic mice, IR in hyperglycemic mice significantly enhanced lung dysfunction, cytokine expression (TNF-α, keratinocyte chemoattractant, IL-6, monocyte chemotactic protein-1, regulated upon activation, normal T cell expressed and secreted), leukocyte infiltration, and microvascular permeability. Lung injury and dysfunction after IR were attenuated in normoglycemic RAGE (-/-) mice, and hyperglycemia failed to exacerbate IR injury in RAGE (-/-) mice. Thus, this study demonstrates that acute hyperglycemia exacerbates lung IR injury, whereas RAGE deficiency attenuates IR injury and also prevents exacerbation of IR injury in an acute hyperglycemic setting. These results suggest that hyperglycemia-enhanced lung IR injury is mediated, at least in part, by RAGE signaling, and identifies RAGE as a potential, novel therapeutic target to prevent post-transplant lung IR injury.