Single-cell sequencing provides insights into the landscape of ovary in PCOS and alterations induced by CUMS.

Polycystic Ovary Syndrome (PCOS) is a common endocrine disorder related to psychological distress. However, the mechanism underlying increased prevalence of depression in PCOS remained unclear. This study aimed to explore the unique transcriptional landscape of ovary and offered a platform to explore the mechanism of PCOS, as well as the influences caused by depression. The PCOS rat model was established by letrozole while PCOS rat model with depression was established by letrozole combined with chronic unpredicted mild stress (CUMS). Then single-cell RNA sequencing (scRNA-Seq) was applied to analyze the transcriptional features of rat ovaries. Granulosa cells (GCs) and fibroblasts (Fibros) accounted for the top 2 clusters of total 12 cell types. There were 9 clusters in GCs, related to inflammatory response, endoplasmic reticulum (ER) stress and steroidogenesis. The expression of DEG Hes1 was higher in PCOS and PCOS+CUMS group, exhibiting enhanced expression by pseudotime and positively related to inflammation. Pseudotemporal analysis revealed that inflammation contributed to the different GCs distributions. Moreover, analysis of DEGs and GO function enrichment revealed CUMS aggravated inflammation in PCOS GCs possibly via interferon signaling pathway. In theca cells (TCs), 9 clusters were observed and some of them were relevant to inflammation, ER stress and lipid metabolism. DEGs Ass1, Insl3, Ifi27 were positively related to Cyp17a1, and Ces1d might contribute to the different trajectory of TCs. Subsequent scRNA-seq revealed signature profile of endothelial cells (ECs) and Fibros, which suggest that inflammation induced damage of ECs and Fibro, further exacerbated by CUMS. Finally, analysis of T cells and mononuclear phagoytes (MPs) revealed the existence of immune dysfunction, among which interferon signaling played a critical role. These findings provided more acknowledge for better understanding PCOS from the view of inflammation and identified new biomarkers and targets for the treatment of PCOS with psychological diseases.