Unraveling the Role of Sex in Endothelial Cell Dysfunction: Evidence From Lineage Tracing Mice and Cultured Cells

Abstract

BACKGROUND: Biological sex differences play a vital role in cardiovascular diseases, including atherosclerosis. The endothelium is a critical contributor to cardiovascular pathologies since endothelial cells (ECs) regulate vascular tone, redox balance, and inflammatory reactions. Although EC activation and dysfunction play an essential role in the early and late stages of atherosclerosis development, little is known about sex-dependent differences in EC. METHODS: We used human and mouse aortic EC as well as EC-lineage tracing ( Cdh5 -CreERT2 Rosa-YFP [yellow fluorescence protein]) atherosclerotic Apoe –/– mice to investigate the biological sexual dimorphism of the EC functions in vitro and in vivo. Bioinformatics analyses were performed on male and female mouse aortic EC and human lung and aortic EC. RESULTS: In vitro, female human and mouse aortic ECs showed more apoptosis and higher cellular reactive oxygen species levels than male EC. In addition, female mouse aortic EC had lower mitochondrial membrane potential (ΔΨm), lower TFAM (mitochondrial transcription factor A) levels, and decreased angiogenic potential (tube formation, cell viability, and proliferation) compared with male mouse aortic EC. In vivo, female mice had significantly higher lipid accumulation within the aortas, impaired glucose tolerance, and lower endothelial-mediated vasorelaxation than males. Using the EC-lineage tracing approach, we found that female lesions had significantly lower rates of intraplaque neovascularization and endothelial-to-mesenchymal transition within advanced atherosclerotic lesions but higher incidents of missing EC lumen coverage and higher levels of oxidative products and apoptosis. RNA-seq analyses revealed that both mouse and human female EC had higher expression of genes associated with inflammation and apoptosis and lower expression of genes related to angiogenesis and oxidative phosphorylation than male EC. CONCLUSIONS: Our study delineates critical sex-specific differences in EC relevant to proinflammatory, pro-oxidant, and angiogenic characteristics, which are entirely consistent with a vulnerable phenotype in females. Our results provide a biological basis for sex-specific proatherosclerotic mechanisms.

Characterization of Atherosclerotic Mice Reveals a Sex-Dependent Susceptibility to Plaque Calcification but No Major Changes in the Lymphatics in the Arterial Wall

“…Furthermore, we found that the popliteal LNs of the female mice on the Western diet were significantly enlarged, proposing an inflammatory process in these mice. These results were in line with a study by Shin et al, who showed that the endothelial cells of female atherosclerotic mice showed a higher expression of the genes associated with inflammation and apoptosis than the males [48]. These results suggest a sex-dependent change in lymphatic function in atherosclerosis, the precise role of which is unclear and highlights the need for further investigating lymphatic function in atherosclerosis.…”

Editorial: Single-cell OMICs analyses in cardiovascular diseases

“…Mizrak et al ( 12 ) using spatial transcriptomics uncovered male-specific smooth muscle cells subpopulation playing a key role in human thoracic aortic aneurysm. ScRNA-seq data from Shin et al ( 13 ) allow to delineate the sex-difference in endothelial cells characteristics and function providing new clues about atherosclerotic diseases. These studies show that inclusion of biological sex in a proper experimental design ( 14 ) is of utmost importance to consider representativeness of the sample population and potential confounding variables.…”