Yourong Feng

The ovarian lymphatic vasculature has emerged as a potential regulator of ovarian function, yet its role in follicular development remains poorly defined. Here, we aimed to elucidate the dynamic changes in ovarian lymphatic vessels during follicular development and to determine whether lymphatic vessels contribute to ovarian function by regulating the immune microenvironment. Ovarian lymphatic remodeling was characterized during different follicular stages, throughout the estrous cycle, and following superovulation using immunofluorescence imaging. Lymphangiogenesis was inhibited with the vascular endothelial growth factor receptor 3 (VEGFR3) inhibitor SAR131675 to evaluate the effects on follicular development and macrophage accumulation in mice. Transcriptomic, tissue localization, and migration assays with C-C motif chemokine ligand 21 (CCL21)- or C-C chemokine receptor type 7 (CCR7)- blocking antibodies were used to investigate CCL21-CCR7 signaling in lymphatic endothelial cell (LEC)-mediated macrophage migration. Ovarian lymphatic vessels underwent dynamic remodeling, with lymphatic density peaking during the luteal phase. Macrophages preferentially localized near lymphatic vessels, and their abundance paralleled lymphatic remodeling across reproductive stages. Inhibition of lymphangiogenesis reduced follicular development, ovulation, corpus luteum formation, and macrophage accumulation. Mechanistically, ovarian lymphatic endothelial cells highly expressed CCL21, which promoted macrophage migration through CCR7 signaling. Collectively, these findings identify ovarian lymphatic vessels as previously unrecognized regulators of the ovarian immune microenvironment, with CCL21-CCR7 signaling mediating lymphatic endothelial cell–macrophage communication to support ovarian function.

Recent studies have highlighted the crucial role of mechanical properties in the ovarian microenvironment for ovarian function. However, the mechanisms that cause ovarian matrix stiffening during aging remain incompletely understood. Here we utilized atomic force microscopy (AFM) to demonstrate that human ovarian matrix stiffness increases with aging and in pathophysiological conditions, such as chemotherapy-induced premature ovarian insufficiency (POI), polycystic ovary syndrome (PCOS) and ovarian endometriosis. By integrating proteomic analysis of human ovarian tissue with transcriptomic profiling of human ovarian fibroblasts, we identified that IL-11, which is elevated in aging ovaries of mice, rats and humans, activates fibroblasts to secrete extracellular matrix (ECM), thereby increasing ovarian matrix stiffness. Genetic deletion of Il11ra1 in mice mitigated the increase in ovarian matrix stiffness and the decline in ovarian function associated with aging, chemotherapy-induced POI and PCOS. Single-nuclei RNA sequencing (snRNA-seq) revealed that blocking Il11ra1 reduces the proportion of activated fibroblasts. Furthermore, administration of siIl11 nanoparticles to aged mice and rats enhanced fertility and reduced ovarian matrix stiffness. Together, these findings highlight the pro-inflammatory factor IL-11 in regulating ovarian matrix stiffness. We propose that anti-IL-11 therapy represents a promising translational strategy for delaying ovarian aging.

Placental extracellular vesicles (EVs) have increasingly been recognized as a major mediator of feto-maternal communication. However, the cellular and molecular mechanisms of the uptake of placental EVs by recipient cells are still not well-understood. We previously reported that placental EVs target a limited number of organs in vivo. In the current study, we investigated the mechanisms underlying the uptake of placental EVs into target cells. Placental EVs were derived from explant cultures of normal or preeclamptic placentae. The mechanisms underlying the uptake of placental EVs were elucidated, using the phagocytosis or endocytosis inhibitor, trypsin-treatment or integrin-blocking peptides. The endothelial cell activation was studied using the monocyte adhesion assay after the preeclamptic EVs exposure, with and/or without treatment with the integrin blocking peptide, YIGSR. The cellular mechanism of the uptake of the placental EVs was time, concentration and energy-dependent and both the phagocytosis and endocytosis were involved in this process. Additionally, proteins on the surface of the placental EVs, including integrins, were involved in the EV uptake process. Furthermore, inhibiting the uptake of preeclamptic EVs with YIGSR, reduced the endothelial cell activation. The interaction between the placental EVs and the recipient cells is mediated by integrins, and the cellular uptake is mediated by a combination of both phagocytosis and endocytosis.