Single-cell RNA sequencing reveals common interactions between follicle immune cells and granulosa cells in premature ovarian insufficiency patients†.

This study aims to investigate the follicle microenvironment of individuals with premature ovarian insufficiency (POI), normal ovarian reserve (normal), and advanced maternal age (AMA), and identify potential therapeutic targets. A total of nine women, including three POI, three normal, and three AMA women, who underwent in vitro fertilization or intracytoplasmic sperm injection were included in this study. For each participant, the first punctured follicle not containing cumulus cells were submitted to single-cell RNA sequencing to explore the characteristics of the follicle microenvironment of POI, normal, and AMA individuals. A total of 87,323 cells were isolated and grouped into six clusters: T cells, B cells, neutrophils, basophils, mononuclear phagocytes, and granulosa cells. Further analysis demonstrated that the population of granulosa cells in cluster 6 was increased in AMA and POI patients, whereas the population of gamma delta T (GDT) cells was decreased. We also found that the genes that were differentially expressed between GDT cells and monocytes were enriched in ribosome- and endoplasmic reticulum (ER)-related pathways. In addition, it showed that VEGFA-FLT1 interaction between the monocytes and granulosa cells may be lost in the AMA and POI patients as compared with the normal group. Loss of the VEGFA-FLT1 interaction in monocytes and granulosa cells, along with enriched ER- and ribosome-related pathways, may drive excess inflammation, accelerating granulosa cell senility and contributing to infertility. This study provides new insights into the pathogenesis of POI and aging and highlights the VEGFA-FLT1 interaction may be a potential therapeutic target for reducing inflammation and treating POI.