Sex-dependent Effects of AHR Activation in Endothelial Cells in Hypoxic Conditions

Chronic kidney disease (CKD) is a risk factor for peripheral arterial disease, however the molecular mechanisms linking the pathobiologies are ill-defined. The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor, has been previously shown to regulate angiogenesis. Notably, CKD results in the accumulation of metabolites that are endogenous ligands for the AHR. Results from animal work showed in male mice with CKD, AHRecKO lead to improvements in limb perfusion without improvements in muscle contractile or mitochondrial function. There was no effect of genotype observed in female mice. To assess these sex-dependent effects we cultured hypoxic endothelial cells from male and female mice and found inherent sex differences in AHR activating potential. Further to this, we performed bulk RNA sequencing and identified several angiogenic genes that were differentially expressed. In summaryn mice with CKD, endothelium-specific deletion of the AHR improved blood perfusion in muscle but did not confer improvement in mitochondrial function or muscle strength. Interestingly, these changes were observed in male, but not female, mice. Cell culture experiments revealed inherent sex-differences in gene expression. To asses the inherenent differenceds in gene expression in endothelial cells as a result of AHR activation and hypoia, we isolated and cultured primary CD31-positive cells from the liver of 4-week old male and female C57BL6/J mice. Cells were treated with 100uM Indoxyl Sulfate (IS) or DMSO control and incubated in hypoxia chamber.