Sex‐Related Differential Gene Expression Underlies Distinct Responses of Adipose Endothelial Cells Under A High‐Fat Diet

Background Despite similar rates of obesity, the prevalence and severity of obesity‐related metabolic diseases is lower in females compared to males. This relates with better preserved function of the adipose tissue in females. Consistent with the importance of capillaries in maintaining tissue functions, insufficient vascularization in expanding adipose tissue leads to adipocyte dysfunction, inflammation and whole‐body metabolic disturbances. Previously, we reported that angiogenesis is higher in the perigonadal adipose tissue in female compared to male mice on a high‐fat diet, leading to a higher capillary density in female adipose. Endothelial cells line capillaries and coordinate different cellular processes involved in angiogenesis, allowing for the necessary vascular remodelling needed in adipose maintenance. We hypothesize that differential gene networks/pathways in the endothelial cells of females compared to males support the better angiogenic response in female adipose tissue. Methods Male and female (5‐7 weeks old; n=4/group) mice were fed a high‐fat diet (60% kcal fat) for 7 weeks. White adipose tissue was harvested and used for whole‐mount imaging and endothelial cell isolation. Adipose tissue was stained with lectin and imaged to determine the vascular density. RNA extracted from the isolated endothelial cells was analyzed by RNA‐sequencing. Transcripts were assessed for differentially expressed genes (DEGs). Gene ontologies and gene set enrichment analysis were used to identify patterns of gene expression. Results Adipose tissue showed greater vascularization in high fat ‐fed females with vascular areas 27.2 ± 2.2 and 21.0 ± 0.6 % field of view in females and males respectively. RNA‐sequencing led to identification of 1225 DEG between male and female endothelial cells (P<0.01). Ontology analyses of the DEGs showed that male endothelial cells expressed higher levels of genes enriched in inflammatory responses and immune processes including chemokine production, complement/coagulation and leukocyte adhesion. In contrast, female endothelial cells lacked an inflammatory signature. Instead, the genes that were higher in female endothelial cells were related to cellular dynamics, such as machinery regulating transcription, translation, DNA replication and axon guidance. Conclusion Adipose endothelial cells from male and female mice have a high number of DEGs that reflect differences in endothelial cell angiogenic phenotype as well as other unique profiles that may be relevant to adipose function. Upregulation of ontologies relating to cellular replication and protein synthesis in females supports the observation of a better angiogenic response in the female adipose tissue and implies that intrinsic differences in male and female endothelial cells contribute to this capacity.