Single-Cell Gene Expression Atlas of Human Follicular Aspirates: Impacts of Leukocytes on the Ovulatory Process

Leukocytes are in situ regulators for ovarian functions. However, little is known about leukocyte subpopulations and functions in ovulatory follicles, especially in humans. This study performed single-cell RNA sequencing and bioinformatics analyses using follicular aspirates obtained from four IVF patients. Nineteen clusters were identified: six follicular cells, ten subsets of leukocytes, and one RBC/platelet. Using dominant follicle tissues collected throughout the periovulatory period from normally cycling women and cultured primary human granulosa/lutein cells, we determined the cell type-specific expression of PTPRC, CD68, IL1B, and IL1R1. RNA velocity analyses revealed developmental dynamics across five granulosa cell groups and two projections of granulosa cell differentiation. To understand how leukocytes promote periovulatory changes, we sought leukocyte-derived factors potentially involved in 1) granulosa cell function by activating their receptors, 2) tissue remodeling, and 3) angiogenesis in ovulatory follicles. Collectively, these findings identified diverse leukocyte-secreted factors that facilitate ovulation and luteinization in the human ovary. Ovarian follicular aspirates obtained from four women undergoing the standardized IVF procedure

白细胞（Leukocytes）是卵巢功能的原位调节因子。然而，目前对于排卵卵泡内的白细胞亚群及其功能尚不清楚，尤以人类为甚。本研究采用从4名体外受精（IVF）患者获取的卵泡抽吸液，开展了单细胞RNA测序（single-cell RNA sequencing）与生物信息学分析。研究共鉴定出19个细胞簇：6个卵泡细胞群、10个白细胞亚群以及1个红细胞/血小板群。研究团队通过采集月经周期正常女性围排卵期各阶段的优势卵泡组织，并体外培养原代人颗粒细胞/黄体化细胞，明确了PTPRC、CD68、IL1B与IL1R1的细胞类型特异性表达特征。RNA速率（RNA velocity）分析揭示了5个颗粒细胞群的发育动态，以及两条颗粒细胞分化轨迹。为阐明白细胞如何促进围排卵期的组织变化，本研究探究了可能参与以下三类过程的白细胞源性因子：1）通过激活受体调控颗粒细胞功能；2）组织重塑；3）排卵卵泡内的血管生成。综上，本研究鉴定出多种可促进人类卵巢排卵与黄体化的白细胞分泌因子。本研究的样本为4名接受标准化体外受精操作的女性的卵巢卵泡抽吸液。