C26-13 Dissecting Sex Differences in Cellular Gene Expression via Single-Cell RNA Sequencing on Pulmonary Hypertension Rats

Background Pulmonary hypertension (PH) exhibits significant differences between the sexes, with female having a higher prevalence and male having a worse prognosis. However, the cellular and molecular mechanisms leading to this difference remain unclear. In this study, we systematically analyzed the cell type-specific gene expression differences between male and female individuals in two PH rat models using single-cell RNA sequencing technology, aiming to fill the gap in the study of the mechanism of sex differences. Hypothesis Using both the monocrotaline (MCT) and Sugen-hypoxia (SuHx) rat models of pulmonary hypertension enables a more comprehensive and robust identification of sex-specific gene expression differences. Approach Male and female rats were divided in three groups: Basal (control), MCT, and SuHx. MCT rats received a monocrotaline injection and were harvested after 4 weeks. SuHx rats were injected with Sugen 5416 and exposed to 10% oxygen for 3 weeks, followed by 2 weeks in normal oxygen. Single-cell RNA sequencing was performed using the 10x Genomics platform. Data were processed with Cell Ranger and analyzed using Seurat. Statistical significance was determined using the Wilcoxon rank-sum test with Bonferroni correction (adjusted p < 0.05). Results We identified six major cell populations: vascular endothelial cells (ECs), fibroblasts, smooth muscle cells/pericytes, myeloid cells, lymphocytes, and epithelial cells. Cell proportion analysis revealed significant sex differences between male and female in both MCT and SuHx rats. For example, SuHx male rats exhibited increased arterial ECs, vascular smooth muscle cells compared to SuHx female. MCT male rats exhibited increased arterial ECs, adventitial fibroblasts T cells compared to MCT female rats. Differential expression analysis revealed significant sex differences between the MCT and SuHx models across multiple cell types. To further explore this, we focused on endothelial cells (ECs). In female rats, we identified 188 differentially expressed genes (DEGs) shared between MCT and SuHx, with 194 DEGs unique to SuHx and 74 unique to MCT. In males, 139 DEGs were shared, while 226 were unique to MCT and 152 unique to SuHx. Conclusion Our findings suggest that the two classical rat models of pulmonary hypertension (PH)-MCT and SuHx-exhibit significant sex differences in multiple cell types and DEGs. These findings emphasize the important role of gender in the pathogenesis of PH.