A porous cervical mucus plug leads to preterm birth induced by experimental vaginal infection in mice

The Known and Unknown About Female Reproductive Tract Mucus Rheological Properties

Spermatozoa reach the fallopian tube during ovulation by traveling through the female reproductive tract mucus. This non-Newtonian viscoelastic medium facilitates spermatozoon movement to accomplish fertilization or, in some cases, blocks spermatozoon movement, leading to infertility. While rheological properties are known to affect spermatozoon motility with in vitro models using synthetic polymers, their precise effects in vivo are understudied. This paper reviews the rheological measurements of reproductive tract mucus during ovulation in humans and model animals, focusing on viscosity and its potential effect on spermatozoa. Mucus viscosity in the female reproductive tract's different compartments is poorly understood. While information on this subject is incomplete, most mammals appear to have a viscosity decrease along their female reproductive tracts. Based on this sparse information, we hypothesize that viscosity changes in female reproductive tracts may guide spermatozoa to eggs, a novel concept that could improve our understanding of reproductive biology.

Identification of early genes in the pathophysiology of fibrotic interstitial lung disease in a new model of pulmonary fibrosis

Some interstitial lung diseases involve pulmonary fibrosis, which is a process that is characterized by the excessive and abnormal accumulation of extracellular matrix in the pulmonary interalveolar space. Although the current anti-fibrotic therapy aims at slowing down the progression of pulmonary fibrosis, it does not reverse it, and many of the drugs that were identified in basic-research studies failed in clinical phases, mainly because of the lack of a model that can recapitulate the pathophysiological mechanisms of human pulmonary fibrosis. We developed a novel experimental model of pulmonary fibrosis induced by a cocktail of molecules on an air/liquid interface culture of mouse embryonic lung explants. Histological analyses revealed a pattern of usual interstitial pneumonia, the worst-prognosis form of pulmonary fibrosis. We performed a transcriptomics analysis at the single-cell level after the induction of fibrosis and before any histological signs of fibrosis could be observed. The results revealed increased expression of several gene families that are involved in early inflammation, fibrosis and iron homeostasis, as well as potential new genetic targets.

Comparative analysis of organoid, air-liquid interface, and direct infection models for studying pathogen-host interactions in endometrial tissue

The endometrium is a critical component of female reproductive health. Endometritis can significantly affect women's health, leading to complications such as infertility, pregnancy failure, and intrauterine adhesions. Therefore, establishing a reliable and effective model of endometritis is essential for advancing research in female reproductive health. The air-liquid interface culture models epithelial exposure to both air and medium, supporting the study of apical-basal polarity and immune responses, but lacks the three-dimensional structure of organoids. Microinjection delivers bacteria directly into the organoid lumen, facilitating the study of bacterial invasion and replication, though it requires advanced technical skills and may not fully replicate natural infections. The direct infection of organoids in suspension culture offers a more realistic model of ascending infections by exposing the basal epithelial surfaces to bacteria, more closely mimicking in vivo conditions. Among the models tested, the direct infection method most accurately mirrors the progression of E. coli infection, showing its advantage in studying bacterial adhesion, replication, and epithelial barrier disruption. Our comparative analysis of microinjection, direct infection, and the ALI model highlighted distinct advantages and challenges associated with each. Microinjection offers precise delivery but is hindered by technical complexity and equipment demands. The ALI model, despite its efficacy, requires extended culture times and limits direct visualization of cell development. Conversely, the direct infection model, which involves the simple removal of Matrigel, proves to be user-friendly, cost-effective, and permits continuous observation of cell behavior. Nonetheless, the direct infection model still presents certain limitations that warrant further optimization.

The costs and benefits of a dynamic host microbiome

All species host a rich community of microbes. This microbiome is dynamic, and displays seasonal, daily, and even hourly changes, but also needs to be resilient to fulfill important roles for the host. In evolutionary ecology, the focus of microbiome dynamism has been on how it can facilitate host adaptation to novel environments. However, an hitherto largely overlooked issue is that the host needs to keep its microbiome in check, which is costly and leads to trade-offs with investing in other fitness-related traits. Investigating these trade-offs in natural vertebrate systems by collecting longitudinal data will lead to deeper insight into the evolutionary mechanisms that shape host-microbiome interactions.

The microbiome biomarkers of pregnant women's vaginal area predict preterm prelabor rupture in Western China

Introduction

Intraamniotic infection is crucial in preterm prelabor rupture of membranes(PPROM), a clinical condition resulting from the invasion of vaginal opportunistic microbes into the amniotic cavity. Although previous studies have suggested potential associations between infection and PPROM, the role of vaginalopportunistic bacteria in PPROM has received limited attention.

Methods

This study aimed to confirm the vaginal bacterial etiology of PPROM. We investigated vaginal microbiotas using automatic analysis of vaginal discharge, microbiological tests, and 16s rRNA genehigh-throughput sequencing.

Results

The research findings revealed that the proportion of parabasal epitheliocytes, leukocytes, toxic leukocytes, and bacteria with diameters smaller than 1.5 um was significantly higher in the PPROM group than that in the normal full-term labor (TL) group. The top three vaginal opportunistic bacterial isolates in all participants were 9.47% Escherichia coli, 5.99% Streptococcus agalactiae, and 3.57% Enterococcus faecalis. The bacterial resistance differed, but all the isolates were sensitive to nitrofurantoin. Compared with the vaginal microbiota dysbiosis (VMD) TL (C) group, the VMD PPROM (P) group demonstrated more operational taxonomic units, a high richness of bacterial taxa, and a different beta-diversity index. Indicator species analysis revealed that Lactobacillus jensenii, Lactobacillus crispatus, and Veillonellaceae bacterium DNF00626 were strongly associated with the C group. Unlike the C group, the indicator bacteria in the P group were Enterococcus faecalis, Escherichia coli, and Streptococcus agalactiae.

Discussion

These findings provide solidevidence that an abnormal vaginal microbiome is a very crucial risk factorclosely related to PPROM. There were no unique bacteria in the vaginalmicrobiota of the PPROM group; however, the relative abundance of bacteria inthe abnormal vaginal flora of PPROM pregnancies differed. Antibiotics should bereasonably selected based on drug sensitivity testing. The findings presented in this paper enhance our understanding of Streptococcus agalactiae, Enterococcus faecalis, and Escherichia coli vaginal bacterial etiology of PPROM in Western China.

Hyposecretion of cervical MUC5B is related to preterm birth in pregnant women after cervical excisional surgery

PROBLEM

Excisional surgery for cervical intraepithelial neoplasia is a risk factor for preterm birth in subsequent pregnancies. However, the underlying mechanisms of this association remain unclear. We previously showed that cervical MUC5B, a mucin protein, may be a barrier to ascending pathogens during pregnancy. We thus hypothesized that hyposecretion of cervical MUC5B is associated with preterm birth after cervical excisional surgery.

METHOD OF STUDY

This prospective nested case-control study (Study 1) included pregnant women who had previously undergone cervical excisional surgery across 11 hospitals. We used proteomics to compare cervicovaginal fluid at 18-22 weeks of gestation between the preterm and term birth groups. In another case-control analysis (Study 2), we compared MUC5B expression in nonpregnant uterine tissues between 15 women with a history of cervical excisional surgery and 26 women without a history of cervical surgery.

RESULTS

The abundance of MUC5B in cervicovaginal fluid was significantly decreased in the preterm birth group (fold change = 0.41, p = .035). Among the 480 quantified proteins, MUC5B had the second highest positive correlation with gestational age at delivery in the combined preterm and term groups. The cervicovaginal microbiome composition was not significantly different between the two groups. Cervical length was not correlated with gestational age at delivery (r = 0.18, p = .079). Histologically, the MUC5B-positive area in the nonpregnant cervix was significantly decreased in women with a history of cervical excisional surgery (0.85-fold, p = .048). The distribution of MUC5B-positive areas in the cervical tissues of 26 women without a history of cervical excisional surgery differed across individuals.

CONCLUSIONS

This study suggests that the primary mechanism by which cervical excisional surgery causes preterm birth is the hyposecretion of MUC5B due to loss of the cervical glands.

Different Forms of TFF3 in the Human Endocervix, including a Complex with IgG Fc Binding Protein (FCGBP), and Further Aspects of the Cervico-Vaginal Innate Immune Barrier

TFF3 is a typical secretory poplypeptide of mucous epithelia belonging to the trefoil factor family (TFF) of lectins. In the intestine, respiratory tract, and saliva, TFF3 mainly exists as a high-molecular-mass complex with IgG Fc binding protein (FCGBP), which is indicative of a role in mucosal innate immunity. For the first time, we identified different forms of TFF3 in the endocervix, i.e., monomeric and homodimeric TFF3, as well as a high-molecular-mass TFF3-FCGBP complex; the latter also exists in a hardly soluble form. Immunohistochemistry co-localized TFF3 and FCGBP. Expression analyses of endocervical and post-menopausal vaginal specimens revealed a lack of mucin and TFF3 transcripts in the vaginal specimens. In contrast, genes encoding other typical components of the innate immune defense were expressed in both the endocervix and vagina. Of note, FCGBP is possibly fucosylated. Endocervical specimens from transgender individuals after hormonal therapy showed diminished expression, particularly of FCGBP. Furthermore, mucus swabs from the endocervix and vagina were analyzed concerning TFF3, FCGBP, and lysozyme. It was the aim of this study to illuminate several aspects of the cervico-vaginal innate immune barrier, which is clinically relevant as bacterial and viral infections are also linked to infertility, pre-term birth and cervical cancer.

Dynamic states of cervical epithelia during pregnancy and epithelial barrier disruption

The cervical epithelium undergoes changes in proliferation, differentiation, and function that are critical to ensure fertility and maintain pregnancy. Here, we identify cervical epithelial subtypes in non-pregnant, pregnant, and in labor mice using single-cell transcriptome and spatial analysis. We identify heterogeneous subpopulations of epithelia displaying spatial and temporal specificity. Notably in pregnancy, two goblet cell subtypes are present in the most luminal layers with one goblet population expanding earlier in pregnancy than the other goblet population. The goblet populations express novel protective factors and distinct mucosal networks. Single-cell analysis in a model of cervical epithelial barrier disruption indicates untimely basal cell proliferation precedes the expansion of goblet cells with diminished mucosal integrity. These data demonstrate how the cervical epithelium undergoes continuous remodeling to maintain dynamic states of homeostasis in pregnancy and labor, and provide a framework to understand perturbations in epithelial health that increase the risk of premature birth.