Advanced glycation endproducts induce cytokine dysregulation and weaken lung epithelial and endothelial barrier integrity

Diabetes mellitus is a systemic disease characterized by chronic hyperglycemia, persistent inflammation, and oxidative stress. While the vascular complications of diabetes are well-documented, their impact on lung barrier integrity remains underexplored. In this study, we investigated the molecular mechanisms by which advanced glycation end-products (AGE) compromise the integrity of lung endothelial and epithelial barriers. Using human lung microvascular endothelial cells and epithelial (A549) cells, we assessed the impact of AGE on the tight junction protein claudin-5, adherens junction protein VE-cadherin, and key signaling molecules including the receptor for AGE (RAGE), phosphorylated Akt, and p38 MAPK as well as a panel of pro-inflammatory cytokines. Our findings demonstrated that AGE exposure (50 μg/mL) significantly activated Akt and p38 MAPK, upregulated Claudin-5 and RAGE, and downregulated VE-cadherin, correlating with reduced transendothelial electrical resistance <i>in vitro</i>. Notably, we observed similar effects on lung epithelial cells. Moreover, AGE-treated conditioned media from THP-1 macrophages induced a pronounced increase in inflammatory cytokines, amplifying the disruption of lung barrier integrity. These findings reveal a potential mechanism linking diabetes-induced vascular dysfunction and immune activation to compromised lung barrier function, emphasizing the need for further research into diabetes-associated lung complications.