Dysregulated ovulatory debris clearance as a driver of ovarian fibroinflammaging

About This Grant

PROJECT SUMMARY The ovary is one of the first organs to age, impacting fertility and endocrine function. The aging ovary is characterized by a loss of egg quantity and quality as well as changes in the microenvironment, including chronic sterile inflammation and fibrosis. “Fibroinflammaging” is a common feature of many aging somatic tissues and is in part driven by accumulation of cellular debris. Interestingly, the ovary has an incredibly dynamic physiology and is under immense pressure to manage cellular debris to maintain tissue homeostasis, which likely explains its accelerated aging. Throughout the reproductive lifespan, the ovary undergoes continuous waves of follicular growth and atresia, cycles of ovulatory rupture, and formation and regression of the corpus luteum (CL), a transient endocrine organ formed post-ovulation. These events require continuous tissue remodeling and result in high cellular debris burden. We have demonstrated that CL regression is dysregulated with age and results in the accumulation of persistent CLs (pCLs) or ovulatory debris. Concomitantly, we identified a unique age- associated macrophage population, multinucleated giant cells (MNGCs), which exhibit pro-inflammatory and degradative phenotypes and stimulate an inflammatory response in follicles and tissue remodeling in the stroma, thus acting as key effectors of fibroinflammaging. Transcriptomically, pCLs are an intermediate between functional CLs and MNGCs and may be a precursor of ovarian MNGC formation. This proposal posits a novel mechanistic framework of ovarian aging mediated by age-related failure to effectively remove ovulatory debris. We will test the hypothesis that age-associated persistent ovulatory debris drives ovarian fibroinflammaging and that enhancing debris clearance mechanisms will improve function and reproductive longevity. In Aim 1, we will define age-related changes in CL regression and the activity of debris clearance mechanisms. Using a CL labeling approach, we will map regression across age and conduct targeted analyses of apoptosis, autophagy, and efferocytosis to investigate how ovarian debris clearance activity is altered. We will also utilize multi-omics approaches to define the content of ovulatory debris. In Aim 2, we will determine how ovulatory debris contributes to MNGC formation and fibroinflammaging. We will leverage mouse models with different degrees of cumulative ovulation to define the relationship between ovulation, debris accumulation, and fibroinflammatory phenotypes. In addition, we will use ex vivo approaches to determine whether CL debris can directly stimulate ovarian MNGC formation. In Aim 3, we will test whether targeted modulation of ovulatory debris impacts ovarian function and healthspan. We will employ a GPNMB-targeted vaccination strategy to deplete pCLs and MNGCs, which exclusively express this marker in the ovary, and assess the effects on reproductive and systemic aging endpoints. Complementary transplantation studies will evaluate the impact of excess pCL burden. This study will establish defective clearance of ovulatory debris as a critical and targetable ovarian aging mechanism.