Abstract Body: Background
Chronic exposure to environmental heavy metals has been increasingly recognized to contribute to vascular disease. Among these metals, cadmium (Cd) exhibits one of the strongest associations with peripheral artery disease (PAD) and disrupts endothelial cell (EC) homeostasis. Iron-responsive element binding protein 2 (IREB2) functions as a critical intracellular iron sensor and coordinates oxidative stress responses. However, its role in endothelial adaptation to ischemia and Cd exposure remains unclear.
Hypothesis
Endothelial IREB2 mitigates Cd-induced vascular injury by activating cellular defense and metal-stress adaptive pathways.
Methods
Single-cell RNA sequencing datasets from human PAD samples were analyzed to assess endothelial IREB2 expression and stress-response pathways. In vitro, ECs with IREB2 overexpression or knockdown were analyzed using transcriptomic profiling, immunoblotting, lysosomal inhibition, and mitochondrial ROS measurements. In vivo, wild-type (Ireb2^fl/fl) and endothelial-specific IREB2 knockout mice (Ireb2^ECKO) were subjected to a hindlimb ischemia model with cadmium exposure, and perfusion recovery was monitored.
Results
Capillary ECs from PAD patients exhibited reduced IREB2 expression and enrichment of cadmium-related stress pathways, including metal-ion response, oxidative stress and metal stress-adaptive response. In ECs, IREB2 overexpression enhanced transcriptional regulation related to cellular defense, metal-stress responses, redox signaling, and metabolic adaptation under cadmium exposure, accompanied by reduced mitochondrial ROS accumulation. In vivo, cadmium exposure significantly impaired post-ischemic blood flow recovery, and this defect was further exacerbated in Ireb2^ECKO mice.
Conclusions
Endothelial IREB2 supports vascular recovery under cadmium stress by cellular defense and redox-adaptive responses. These findings identify IREB2 as a critical regulator of endothelial adaptation to environmental heavy metal stress and suggest a mechanistic link between cadmium exposure and impaired vascular repair in PAD.