Intrinsic transcriptomic sex differences in human endothelial cells at birth and in adults are associated with coronary artery disease targets

Abstract

Sex differences in endothelial cell (EC) biology may reflect intrinsic differences driven by chromosomes or sex steroid exposure and gender differences accumulated over life. We analysed EC gene expression data from boy-girl twins at birth and in non-twin adults to detect sex differences at different stages of life, and show that 14-25% of the EC transcriptome is sex-biased. By combining data from both stages of life, we identified sex differences that are present at birth and maintained throughout life, and those that are acquired over life. Promisingly, we found that genes that present with an acquired sex difference in ECs are more likely to be targets of sex steroids. Annotating both gene sets with data from multiple genome-wide association studies (GWAS) revealed that genes with an intrinsic sex difference in ECs are enriched for coronary artery disease GWAS hits. This study underscores the need for treating sex as a biological variable. Abbreviations CAD Coronary artery disease DEG Differentially expressed gene EC Endothelial cell HAEC Human aortic endothelial cell HUVEC Human umbilical vein endothelial cell GWAS Genome-wide association study Endothelial cells (ECs) are located at the innermost lining of all vessels and are responsible for circulatory homeostasis. ECs are implicated in a plethora of functions, such as water and nutrient transfer, inflammation, vascular tension, hemostasis, and angiogenesis 1. Differences in EC biology between the sexes have been described, indicating that sex is an important variable in EC biology 2. Studies focussing on functional differences, i.e. migration, proliferation, and shear stress response, imply sex differences in regulation of key endothelial pathways, such as the redox system 3-5. Differences between female and male cells might be present from birth onwards, or acquired later in life because of sex steroid exposure and gender differences. Pinpointing master regulators herein has been difficult, as differences between the sexes may be caused by sex hormones and/or sex chromosomes, which are difficult to study separately or to dissect. Transcriptomic studies of female and male (endothelial) cells shed light on differentially expressed genes (DEGs) between the sexes and their regulators, but few have been performed thus far on ECs 4. Tissue-specific comparisons have been made using publicly available data from the

Sex-dependent differences in the secretome of human endothelial cells

“…In fact, HUVECs undergo in vitro angiogenesis, produce NO, and respond to shear stress, hyperglycemia, and inflammatory stimuli, thus recapitulating human disease pathophysiology. In addition, sex-dependent differences in the gene expression and functional properties have been shown in male and female HUVECs by us and other groups [ 12 – 14 , 17 , 18 , 70 ], indicating HUVECs as a suitable model for studying cellular biological sex and increasing the translational value of basic research. Nevertheless, whether and through which mechanisms HUVEC dimorphic properties are lifelong conserved and regulated in adult male and female ECs still need to be deeper investigated.…”

“…Nevertheless, whether and through which mechanisms HUVEC dimorphic properties are lifelong conserved and regulated in adult male and female ECs still need to be deeper investigated. However, a transcriptome analysis comparing HUVECs to adult human ECs has very recently shown that more than 250 genes are concordantly differentially expressed between sexes at birth and in adults [ 70 ], thus further supporting the use of HUVECs as a valuable model for basic research on the endothelium.…”

Human Umbilical Cord: Information Mine in Sex-Specific Medicine

“…Using twin pairs to study sex differences in transcriptome, Hartaman and colleagues observed that HUVECs from twins of different sexes (male/female) had greater differences in their transcriptome (2528 differentially expressed gene versus 79 in the comparison boy–boy versus girl–girl twins) than HUVECs from twins of the same sex (both male/male and female/female pairs). Females in boy/girl twins showed higher activation of endothelial pathways (endothelial to mesenchymal transition, hypoxia and nuclear factor-kappa B signaling), while males had significantly higher expression of Myc targets, oxidative phosphorylation and mTOR signaling [ 143 ]. Interestingly, some of the detected sex differences were maintained throughout life, confirming that sexual dimorphism starts in utero [ 143 ].…”

“…Females in boy/girl twins showed higher activation of endothelial pathways (endothelial to mesenchymal transition, hypoxia and nuclear factor-kappa B signaling), while males had significantly higher expression of Myc targets, oxidative phosphorylation and mTOR signaling [ 143 ]. Interestingly, some of the detected sex differences were maintained throughout life, confirming that sexual dimorphism starts in utero [ 143 ].…”

Developmental programming in human umbilical cord vein endothelial cells following fetal growth restriction

“…Directly after placental delivery, the umbilical cord was stored in phosphate buffered saline (PBS) solution (pH 7.2;) at 4 °C. HUVECs isolation occurred preferably within 12 h, but always within 24 h after placental delivery as described [ 18 ]. Umbilical cords from n = 8 control and n = 12 FGR cases were collected.…”