Dynamic states of cervical epithelia during pregnancy and epithelial barrier disruption

Improving the safety of N,N-dimethylacetamide (DMA) as a potential treatment for preterm birth in a pregnant mouse model using a vaginal nanoformulation

Vaginal administration and the uterine first pass effect allow for preferential delivery of drugs to the reproductive tract. Dimethylacetamide has previously been shown to delay preterm birth in a pregnant mouse model when given intraperitoneally but the effectiveness of a vaginal nanoformulation of dimethylacetamide has yet to be tested. The purpose of this study was to compare the two formulations of dimethylacetamide for efficacy in rescuing pups from preterm birth in an inflammation-induced mouse model, effects on the maternal fetal interface, and pharmacokinetic profiles in maternal plasma. Timed pregnant CD1 mice were given a 1.56 mg/kg intraperitoneal dose of lipopolysaccharide followed by 3 doses of either vaginal dimethylacetamide or intraperitoneal dimethylacetamide. Mice were monitored for 48 h and times of deliveries were recorded. Additionally, CD1 mice in late gestation were given a single dose of either vaginal or intraperitoneal dimethylacetamide and blood was drawn at 3 different time points following administration. Vaginal administration of dimethylacetamide had similar efficacy in delaying inflammation induced preterm birth as intraperitoneal administration but resulted in lower concentrations in the systemic circulation and decreased effects on the maternal fetal interface. Vaginal nanoformulations should be explored for their potential therapeutic value for the delay of preterm birth.

Collagen turnover during cervical remodeling involves both intracellular and extracellular collagen degradation pathways†

Reproductive success requires accurately timed remodeling of the cervix to orchestrate the maintenance of pregnancy, the process of labor, and birth. Prior work in mice established that a combination of continuous turnover of fibrillar collagen and reduced formation of collagen cross-links allows for the gradual increase in tissue compliance and delivery of the fetus during labor. However, the mechanism for continuous collagen degradation to ensure turnover during cervical remodeling is still unknown. This study demonstrates the functional role of extracellular and intracellular collagen degradative pathways in two different settings of cervical remodeling: physiological term remodeling and inflammation-mediated premature remodeling. Extracellular collagen degradation is achieved by the activity of fibroblast-derived matrix metalloproteases MMP14, MMP2, and fibroblast activation protein (FAP). In parallel, we demonstrate the function of an intracellular collagen degradative pathway in fibroblast cells mediated by the collagen endocytic mannose receptor type-2 (MRC2). These pathways appear to be functionally redundant as loss of MRC2 does not obstruct collagen turnover or cervical function in pregnancy. While both extracellular and intracellular pathways are also utilized in inflammation-mediated premature cervical remodeling, the extracellular collagen degradation pathway uniquely employs fibroblast and immune-cell-derived proteases. In sum, these findings identify the dual utilization of two distinct degradative pathways as a failsafe mechanism to achieve continuous collagen turnover in the cervix, thereby allowing dynamic shifts in cervical tissue mechanics and function.

Cervical function in pregnancy and disease: new insights from single-cell analysis

The uterine cervix plays an essential role in regulating fertility, maintaining pregnancy, remodeling in preparation for parturition, and protecting the reproductive tract from infection. A compromise in cervical function contributes to adverse clinical outcomes. Understanding molecular events that drive the multifunctional and temporally defined roles of the cervix is necessary to effectively treat infertility, reproductive tract infections, preterm birth, labor dystocia, and cervical cancer. The application of single-cell technologies to study cervical pathophysiology, while in its infancy, underscores the potential of these approaches in developing clinically relevant biomarkers of disease and preventative therapies. This review focuses on insights gained from single-cell transcriptomic studies in human and mouse cervical tissue and highlights outstanding questions in the field. One collective advance from single-cell analysis is the dynamic plasticity of cervical epithelial cells during the reproductive cycle in health and disease. Single-cell comparisons between upper and lower regions of the reproductive tract also highlight the distinct and divergent immunological responses elicited in the cervix during the reproductive lifespan. These findings may reconcile prior controversies in the role of proinflammatory mediators during parturition. In addition to providing obstetric insights, single-cell technologies elucidate the molecular pathways that drive cervical cancer progression. Thus far, these technologies have uncovered cellular heterogeneity in the tumor microenvironment and have identified potential cancer stem cells. While single-cell technology alone will not uncover all the molecular underpinnings contributing to preterm birth or cervical cancer, the insights derived from this valuable technology will accelerate our understanding of cervical biology in health and disease, which ultimately will help develop biomarkers for disease prediction and prevention therapies.

Decoding Müllerian Duct Epithelial Regionalization

Müllerian ducts (MD), also known as paramesonephric ducts, are the primordial anlage of the female reproductive tract organs including the oviduct, uterus, cervix and upper vagina along the craniocaudal axis. Although the general architecture of MD-derived organs is conserved, each organ possesses their unique epithelial structures and cell types to confer their region-specific functions, which collectively coordinate successful fertilization and pregnancy. MD epithelial fate decisions and differentiation along the craniocaudal axis is dependent on spatiotemporal regulation of intrinsic transcription factors and extrinsic signals derived from the mesenchyme. Findings from genetic mouse models, single-cell sequencing studies, and organoid cultures have significantly advanced our understanding of the cellular and molecular mechanisms of MD regionalization. In this review, we first discuss the diversity of epithelial morphologies and cell types in the female reproductive tract organs. Then, we discuss the roles of key transcription factors (Hox, transcriptional cascade driving multiciliogenesis, Foxa2, and P63), signaling pathways (estrogen/ESR1, Wnt/β-catenin, hedgehog, and retinoic acid), and epigenetic factors (microRNAs, chromatin remodeling factors, and histone modification enzymes) in region-specific MD differentiation. Further deciphering molecular mechanisms of MD craniocaudal patterning will open new avenues to improve our strategies for prevention, diagnosis, and treatment of Müllerian anomalies and female reproductive tract disorders.

Improving the Safety of N,N-Dimethylacetamide (DMA) as a Potential Treatment for Preterm Birth in a Pregnant Mouse Model Using a Vaginal Nanoformulation

Vaginal administration and the uterine first pass effect allow for preferential delivery of drugs to the reproductive tract. Dimethylacetamide has previously been shown to delay preterm birth in a pregnant mouse model when given intraperitoneally but the effectiveness of a vaginal nanoformulation of dimethylacetamide has yet to be tested. The purpose of this study was to compare the two formulations of dimethylacetamide for efficacy in rescuing pups from preterm birth in an inflammation-induced mouse model, effects on the maternal fetal interface, and pharmacokinetic profiles in maternal plasma. Timed pregnant CD1 mice were given a 1.56 mg/kg intraperitoneal dose of lipopolysaccharide followed by 3 doses of either vaginal dimethylacetamide or intraperitoneal dimethylacetamide. Mice were monitored for 48 hours and times of deliveries were recorded. Additionally, CD1 mice in late gestation were given a single dose of either vaginal or intraperitoneal dimethylacetamide and blood was drawn at 3 different time points following administration. Vaginal administration of dimethylacetamide had similar efficacy in delaying inflammation induced preterm birth as intraperitoneal administration but resulted in lower concentrations in the systemic circulation and decreased effects on the maternal fetal interface. Vaginal nanoformulations should be explored for their potential therapeutic value for the delay of preterm birth.

Regional differences in three-dimensional fiber organization, smooth muscle cell phenotype, and contractility in the pregnant mouse cervix

The orientation and function of smooth muscle in the cervix may contribute to the important biomechanical properties that change during pregnancy. Thus, this study examined the three-dimensional structure, smooth muscle phenotype, and mechanical and contractile functions of the upper and lower cervix of nongravid (not pregnant) and gravid (pregnant) mice. In gravid cervix, we uncovered region-specific changes in the structure and organization of fiber tracts. We also detected a greater proportion of contractile smooth muscle cells (SMCs), but an equal proportion of synthetic SMCs, in the upper versus lower cervix. Furthermore, we revealed that the lower cervix had infrequent spontaneous contractions, distension had a minimal effect on contractility, and the upper cervix had forceful contractions in response to labor-inducing agents (oxytocin and prostaglandin E2). These findings identify regional differences in cervix contractility related to contractile SMC content and fiber organization, which could be targeted with diagnostic technologies and for therapeutic intervention.

Pregnancy-Related Precancerous Cervical Lesions: Pathogenesis, Diagnosis, Evolution, and Impact upon Gestation and Fertility

More common than cervical cancer, cervical intraepithelial neoplasia (CIN) represents a precursor lesion of cervical carcinoma, being associated with HPV infection. Due to the bidirectional relationship between HPV and estrogen and progesterone in pregnancy, most of the published data claim that precancerous lesions remain stable or even regress during pregnancy, although several studies have indicated the tendency of HSILs to persist. It is considered that pregnancy-related cervical precancerous lesions undergo a postpartum regression, due to stimulatory effects of the immune microenvironment. Due to the rarity of publications on this subject, we aimed to offer a concise overview of and new insights into the current knowledge regarding the pathogenesis, diagnosis, and evolution of pregnancy-associated precancerous lesions, as well as their impact upon gestation and fertility.

Epithelial organoid supports resident memory CD8 T cell differentiation

Resident memory T cells (TRMs) play a vital role in regional immune defense. Although laboratory rodents have been extensively used to study fundamental TRM biology, poor isolation efficiency and low cell survival rates have limited the implementation of TRM-focused high-throughput assays. Here, we engineer a murine vaginal epithelial organoid (VEO)-CD8 T cell co-culture system that supports CD8 TRM differentiation. These in-vitro-generated TRMs are phenotypically and transcriptionally similar to in vivo TRMs. Pharmacological and genetic approaches showed that transforming growth factor β (TGF-β) signaling plays a crucial role in their differentiation. The VEOs in our model are susceptible to viral infections and the CD8 T cells are amenable to genetic manipulation, both of which will allow a detailed interrogation of antiviral CD8 T cell biology. Altogether we have established a robust in vitro TRM differentiation system that is scalable and can be subjected to high-throughput assays that will rapidly add to our understanding of TRMs.

Mucus production, host-microbiome interactions, hormone sensitivity, and innate immune responses modeled in human cervix chips

Modulation of the cervix by steroid hormones and commensal microbiome play a central role in the health of the female reproductive tract. Here we describe organ-on-a-chip (Organ Chip) models that recreate the human cervical epithelial-stromal interface with a functional epithelial barrier and production of mucus with biochemical and hormone-responsive properties similar to living cervix. When Cervix Chips are populated with optimal healthy versus dysbiotic microbial communities (dominated by Lactobacillus crispatus and Gardnerella vaginalis, respectively), significant differences in tissue innate immune responses, barrier function, cell viability, proteome, and mucus composition are observed that are similar to those seen in vivo. Thus, human Cervix Organ Chips represent physiologically relevant in vitro models to study cervix physiology and host-microbiome interactions, and hence may be used as a preclinical testbed for development of therapeutic interventions to enhance women's health.

Ovarian sex steroid and epithelial control of immune responses in the uterus and oviduct: human and animal models†

The female reproductive tract (FRT), including the uterus and oviduct (Fallopian tube), is responsible for maintaining an optimal microenvironment for reproductive processes, such as gamete activation and transportation, sperm capacitation, fertilization, and early embryonic and fetal development. The mucosal surface of the FRT may be exposed to pathogens and sexually transmitted microorganisms due to the opening of the cervix during mating. Pathogens and endotoxins may also reach the oviduct through the peritoneal fluid. To maintain an optimum reproductive environment while recognizing and killing pathogenic bacterial and viral agents, the oviduct and uterus should be equipped with an efficient and rigorously controlled immune system. Ovarian sex steroids can affect epithelial cells and underlying stromal cells, which have been shown to mediate innate and adaptive immune responses. This, in turn, protects against potential infections while maintaining an optimal milieu for reproductive events, highlighting the homeostatic involvement of ovarian sex steroids and reproductive epithelial cells. This article will discuss how ovarian sex steroids affect the immune reactions elicited by the epithelial cells of the non-pregnant uterus and oviduct in the bovine, murine, and human species. Finally, we propose that there are regional and species-specific differences in the immune responses in FRT.

Anatomy of the female reproductive tract organs of the brown anole (Anolis sagrei)

Female reproduction in squamate reptiles (lizards and snakes) is highly diverse and mode of reproduction, clutch size, and reproductive tract morphology all vary widely across this group of ~11,000 species. Recently, CRISPR genome editing techniques that require manipulation of the female reproductive anatomy have been developed in this group, making a more complete understanding of this anatomy essential. We describe the adult female reproductive anatomy of the model reptile the brown anole (Anolis sagrei). We show that the brown anole female reproductive tract has three distinct anterior-to-posterior regions, the infundibulum, the glandular uterus, and the nonglandular uterus. The infundibulum has a highly ciliated epithelial lip, a region where the epithelium is inverted so that cilia are present on the inside and outside of the tube. The glandular uterus has epithelial ducts that are patent with a lumen as well as acinar structures with a lumen. The nonglandular uterus has a heterogeneous morphology from anterior to posterior, with a highly folded, ciliated epithelium transitioning to a stratified squamous epithelium. This transition is accompanied by a loss of keratin-8 expression and together, these changes are similar to the morphological and gene expression changes that occur in the mammalian cervix. We recommend that description of the nonglandular uterus include the regional sub-specification of a "cervix" and "vagina" as this terminology change more accurately describes the morphology. Our data extend histological studies of reproductive organ morphology in reptiles and expand our understanding of the variation in reproductive system anatomy across squamates and vertebrates.

Protocol to dissociate epithelia from non-pregnant and pregnant mouse cervical tissue for single-cell RNA-sequencing

A challenge in studying cervical epithelial cell biology at the single-cell level is that differentiated subtypes, in particular mucus-secreting goblet cells, are sensitive to disassociating enzymes making isolation of all epithelial subpopulations difficult. Here we present a protocol to dissociate epithelia from non-pregnant and pregnant mouse cervical tissue for single-cell RNA-sequencing. We describe steps for harvesting cervices, preparing cervical tissue, dissociation of cervical cells, and viability checks. We then detail library preparation, sequencing, and procedure for data analysis. For complete details on the use and execution of this protocol, please refer to Cooley et al. (2023).1.

Epithelial organoid supports resident memory CD8 T cell differentiation

Resident Memory T cells (TRM) play a vital role in regional immune defense in barrier organs. Although laboratory rodents have been extensively used to study fundamental TRM biology, poor isolation efficiency, sampling bias and low cell survival rates have limited our ability to conduct TRM-focused high-throughput assays. Here, we engineered a murine vaginal epithelial organoid (VEO)-CD8 T cell co-culture system that supports CD8 TRM differentiation in vitro. The three-dimensional VEOs established from murine adult stem cells resembled stratified squamous vaginal epithelium and induced gradual differentiation of activated CD8 T cells into epithelial TRM. These in vitro generated TRM were phenotypically and transcriptionally similar to in vivo TRM, and key tissue residency features were reinforced with a second cognate-antigen exposure during co-culture. TRM differentiation was not affected even when VEOs and CD8 T cells were separated by a semipermeable barrier, indicating soluble factors' involvement. Pharmacological and genetic approaches showed that TGF-β signaling played a crucial role in their differentiation. We found that the VEOs in our model remained susceptible to viral infections and the CD8 T cells were amenable to genetic manipulation; both of which will allow detailed interrogation of antiviral CD8 T cell biology in a reductionist setting. In summary, we established a robust model which captures bonafide TRM differentiation that is scalable, open to iterative sampling, and can be subjected to high throughput assays that will rapidly add to our understanding of TRM.

Stromal cells-specific retinoic acid determines parturition timing at single-cell and spatial-temporal resolution

The underlying mechanisms governing parturition remain largely elusive due to limited knowledge of parturition preparation and initiation. Accumulated evidences indicate that maternal decidua plays a critical role in parturition initiation. To comprehensively decrypt the cell heterogeneity in decidua approaching parturition, we investigate the roles of various cell types in mouse decidua process and reveal previously unappreciated insights in parturition initiation utilizing single-cell RNA sequencing (scRNA-seq). We enumerate the cell types in decidua and identity five different stromal cells populations and one decidualized stromal cells. Furthermore, our study unravels that stromal cells prepare for parturition by regulating local retinol acid (RA) synthesis. RA supplement decreases expression of extracellular matrix-related genes in vitro and accelerates the timing of parturition in vivo. Collectively, the discovery of contribution of stromal cells in parturition expands current knowledge about parturition and opens up avenues for the intervention of preterm birth (PTB).