The Impact of Leukocyte-derived Cytokines on Ovulation in Humans

PROJECT SUMMARY/ABSTRACT Mid-cycle gonadotropin-induced ovulation, a pivotal event in female reproductive physiology, shares many features with an acute inflammatory response, notably marked by a substantial influx of leukocytes into the dominant follicle. Despite this, the precise impact of leukocytes on the ovulatory process remains largely uncharted territory. This knowledge gap serves as the foundation of the proposed study, which endeavors to elucidate the role of leukocytes in facilitating ovulation and luteinization in the human ovary. Our preliminary findings, derived from single-cell RNA sequencing (scRNA-seq) analysis using follicular aspirates obtained from in vitro fertilization patients (due to male factor or egg donation), have revealed the presence of ten distinct leukocyte subpopulations. Furthermore, based on the single-cell transcriptomic datasets, we found that inflammatory cytokines are exclusively expressed in leukocytes, while the expression of their corresponding receptors is abundantly detected in follicular (granulosa and theca) cells. Therefore, we hypothesize that these cytokines and their receptors play a pivotal role in ovulatory changes, including steroid hormone and prostaglandin production, as well as cell metabolic shifts in the human periovulatory follicle. In Specific Aim 1, we will comprehensively delve into characterizing the expression profile of these cytokines and their corresponding receptors in dominant follicles throughout the ovulatory period, analyzing samples obtained from regularly cycling women before and at defined hours after human chorionic gonadotropin (hCG) administration to understand spatiotemporal dynamics of leukocyte-derived cytokines and their corresponding receptors. Also, we will determine the regulatory mechanisms by which hCG increases the expression of the receptors for the leukocyte-derived cytokines using primary human granulosa/lutein cells (hGLCs). Specific Aim 2 focuses on elucidating the impact of these leukocyte-derived cytokines and their corresponding receptors in granulosa cells on the ovulatory process. By treating hGLCs with hCG, cytokines, and/or receptor antagonists, we aim to uncover the underlying signaling pathways and associated functional changes facilitating ovulation and luteal formation in the human ovary. The implications of this proposed study extend beyond advancing our understanding of normal ovulation; it also holds significant promise for addressing female infertility caused by inflammation-related ovarian conditions. By shedding light on these intricate mechanisms, our research has the potential to provide invaluable insights into the development of innovative therapeutic strategies aimed at improving women’s reproductive health and fertility.