Predictive value of cervical cytokine, antimicrobial and microflora levels for pre-term birth in high-risk women

Describing Biological Vulnerability in Small, Vulnerable Newborns in Urban Burkina Faso (DenBalo): Gut Microbiota, Immune System, and Breastmilk Assembly

Background: Small vulnerable newborns (SVNs), including those born preterm, small for gestational age, or with low birth weight, are at higher risk of neonatal mortality and long-term health complications. Early exposure to maternal vaginal microbiota and breastfeeding plays a critical role in the development of the neonatal microbiota and immune system, especially in low-resource settings like Burkina Faso, where neonatal mortality rates remain high. Objectives: The DenBalo study aims to investigate the role of maternal and neonatal factors, such as vaginal and gut microbiota, immune development, and early nutrition, in shaping health outcomes in SVNs and healthy infants. Methods: This prospective cohort observational study will recruit 141 mother-infant pairs (70 SVNs and 71 healthy controls) from four health centers in Bobo-Dioulasso, Burkina Faso. The mother-infant pairs will be followed for six months with anthropometric measurements and biospecimen collections, including blood, breast milk, saliva, stool, vaginal swabs, and placental biopsies. Multi-omics approaches, encompassing metagenomics, metabolomics, proteomics, and immune profiling, will be used to assess vaginal and gut microbiota composition and functionality, immune cell maturation, and cytokine levels at critical developmental stages. Conclusions: This study will generate comprehensive data on how microbiota, metabolomic, and proteomic profiles, along with immune system development, differ between SVNs and healthy infants. These findings will guide targeted interventions to improve neonatal health outcomes and reduce mortality, particularly in vulnerable populations.

Predicting Preterm Birth Using Proteomics

The complexity of preterm birth (PTB), both spontaneous and medically indicated, and its various etiologies and associated risk factors pose a significant challenge for developing tools to accurately predict risk. This review focuses on the discovery of proteomics signatures that might be useful for predicting spontaneous PTB or preeclampsia, which often results in PTB. We describe methods for proteomics analyses, proteomics biomarker candidates that have so far been identified, obstacles for discovering biomarkers that are sufficiently accurate for clinical use, and the derivation of composite signatures including clinical parameters to increase predictive power.

Immune regulation by activation markers at feto-maternal interface in infection-associated spontaneous preterm birth

BACKGROUND

Spontaneous preterm birth (sPTB) is a global health concern. Studies reveal infections are majorly responsible for sPTB and immune activation markers play a role in regulation of maternal immune responses against pathogens during sPTB.

AIM

To study the mRNA expression and correlation of activation markers (CD66a, ICAM1, ITGB1, TIM3, CD25, CD95) and associated cytokines (IL-1β and IL-17)/prostaglandin receptors (EP2 and IP) in the placenta of Chlamydia trachomatis, Mycoplasma hominis, Ureaplasma urealyticum-infected sPTB women.

METHODS

Placental samples were collected from 160 sPTB and 160 term birth women. PCR was used for the detection of C. trachomatis, M. hominis, U. urealyticum. The mRNA expression of activation markers, cytokines and prostaglandin receptors was evaluated by real-time qPCR.

RESULTS

The fold-change expression of CD66a, ICAM1, TIM3, CD25 and CD95 was 2.89, 5.5, 4.95, 6.44 and 6.95-fold (p < 0.001), respectively; while for cytokines- IL-1β and IL-17 was 5.41 and 4.71-fold (p < 0.001), respectively and for prostaglandin receptors- EP2 and IP was 5.5 and 5-fold (p < 0.001) upregulated, respectively in infected sPTB women. Significant positive correlation was obtained among ICAM-1 and IL-1β/EP2/IL-17, TIM3 and IP/IL-17. Significant negative correlation was obtained between CD66a and EP2/IL-17, CD25 and IL-1β/EP2, CD95 and IL-1β/EP2 in infected sPTB women.

CONCLUSIONS

CD66a, ICAM1 and TIM3 may play role in inflammation and have potential for the clinical beginning of preterm labour during infection while CD25 and CD95 are possibly involved in immunotolerance at feto-maternal interface during C. trachomatis, M. hominis and U. urealyticum infection.

Defensins: defenders of human reproductive health

BACKGROUND

Reproductive tract infection is an important factor leading to male and female infertility. Among female infertility factors, microbial and viral infections are the main factors affecting female reproductive health and causing tubal infertility, ectopic tubal pregnancy and premature delivery. Among male infertility factors, 13-15% of male infertility is related to infection. Defensins are cationic antibacterial and antiviral peptides, classified into α-defensins, β-defensins and θ-defensins. Humans only have α-defensins and β-defensins. Apart from their direct antimicrobial functions, defensins have an immunomodulatory function and are involved in many physiological processes. Studies have shown that defensins are widely distributed in the female reproductive tract (FRT) and male reproductive tract (MRT), playing a dual role of host defence and fertility protection. However, to our knowledge, the distribution, regulation and function of defensins in the reproductive tract and their relation to reproduction have not been reviewed.

OBJECTIVE AND RATIONALE

This review summarizes the expression, distribution and regulation of defensins in the reproductive tracts to reveal the updated research on the dual role of defensins in host defence and the protection of fertility.

SEARCH METHODS

A systematic search was conducted in PubMed using the related keywords through April 2022. Related data from original researches and reviews were integrated to comprehensively review the current findings and understanding of defensins in the human reproductive system. Meanwhile, female and male transcriptome data in the GEO database were screened to analyze defensins in the human reproductive tracts.

OUTCOMES

Two transcriptome databases from the GEO database (GSE7307 and GSE150852) combined with existing researches reveal the expression levels and role of the defensins in the reproductive tracts. In the FRT, a high expression level of α-defensin is found, and the expression levels of defensins in the vulva and vagina are higher than those in other organs. The expression of defensins in the endometrium varies with menstrual cycle stages and with microbial invasion. Defensins also participate in the local immune response to regulate the risk of spontaneous preterm birth. In the MRT, a high expression level of β-defensins is also found. It is mainly highly expressed in the epididymal caput and corpus, indicating that defensins play an important role in sperm maturation. The expression of defensins in the MRT varies with androgen levels, age and the status of microbial invasion. They protect the male reproductive system from bacterial infections by neutralizing lipopolysaccharide and downregulating pro-inflammatory cytokines. In addition, animal and clinical studies have shown that defensins play an important role in sperm maturation, motility and fertilization.

WIDER IMPLICATIONS

As a broad-spectrum antimicrobial peptide without drug resistance, defensin has great potential for developing new natural antimicrobial treatments for reproductive tract infections. However, increasing evidence has shown that defensins can not only inhibit microbial invasion but can also promote the invasion and adhesion of some microorganisms in certain biological environments, such as human immunodeficiency virus. Therefore, the safety of defensins as reproductive tract anti-infective drugs needs more in-depth research. In addition, the modulatory role of defensins in fertility requires more in-depth research since the current conclusions are based on small-size samples. At present, scientists have made many attempts at the clinical transformation of defensins. However, defensins have problems such as poor stability, low bioavailability and difficulties in their synthesis. Therefore, the production of safe, effective and low-cost drugs remains a challenge.

Biomarkers for Preterm Delivery

Preterm birth occurring before the thirty-seventh gestational week complicates 4.5%-18% of pregnancies worldwide. The pathogenesis of spontaneous preterm delivery is not fully understood. Among the factors held to be responsible for its pathogenesis, the most emphasized is the inflammatory process. Studies in terms of the prediction of preterm delivery are basically divided into 3 categories: 1) Prediction in pregnant women who are asymptomatic and without risk factors, 2) Prediction in pregnant women who are asymptomatic and have risk factors, 3) Prediction in symptomatic pregnant women who have threatened preterm labour. In this chapter, the topic of biomarkers in relation to preterm delivery is discussed. The most commonly used markers in published studies are fetal fibronectin, cervical pIGFBP-1 and cervical length measurement by transvaginal ultrasound. For prediction in symptomatic pregnant women applying to the hospital with threatened preterm labour, the markers used are fetal fibronection, insulin-like growth factors (IGFs) and inflammatory markers. Preterm labour prediction with markers checked in the first and second trimesters are fetal fibronection, insulin-like growth factors (IGFs), micro RNAs, progesterone, circulating microparticles (CMPs), inflammatory markers, matrix metalloproteinases, aneuploidy syndrome screening test parameters and other hormones.

Breaking Down the Barrier: The Role of Cervical Infection and Inflammation in Preterm Birth

Approximately 40% of cases of spontaneous preterm birth (sPTB) are associated with ascending intrauterine infections. The cervix serves as a physical and immunological gatekeeper, preventing the ascent of microorganisms from the vagina to the amniotic cavity. The cervix undergoes remodeling during pregnancy. It remains firm and closed from the start until the late third trimester of pregnancy and then dilates and effaces to accommodate the passage of the fetus during delivery. Remodeling proceeds appropriately and timely to maintain the pregnancy until term delivery. However, risk factors, such as acute and chronic infection and local inflammation in the cervix, may compromise cervical integrity and result in premature remodeling, predisposing to sPTB. Previous clinical studies have established bacterial (i.e., chlamydia, gonorrhea, mycoplasma, etc.) and viral infections (i.e., herpesviruses and human papillomaviruses) as risk factors of PTB. However, the exact mechanism leading to PTB is still unknown. This review focuses on: (1) the epidemiology of cervical infections in pregnant patients; (2) cellular mechanisms that may explain the association of cervical infections to premature cervical ripening and PTB; (3) endogenous defense mechanisms of the cervix that protect the uterine cavity from infection and inflammation; and (4) potential inflammatory biomarkers associated with cervical infection that can serve as prognostic markers for premature cervical ripening and PTB. This review will provide mechanistic insights on cervical functions to assist in managing cervical infections during pregnancy.

Development of a mouse model of ascending infection and preterm birth

BACKGROUND

Microbial invasion of the intraamniotic cavity and intraamniotic inflammation are factors associated with spontaneous preterm birth. Understanding the route and kinetics of infection, sites of colonization, and mechanisms of host inflammatory response is critical to reducing preterm birth risk.

OBJECTIVES

This study developed an animal model of ascending infection and preterm birth with live bacteria (E. coli) in pregnant CD-1 mice with the goal of better understanding the process of microbial invasion of the intraamniotic cavity and intraamniotic inflammation.

STUDY DESIGN

Multiple experiments were conducted in this study. To determine the dose of E. coli required to induce preterm birth, CD-1 mice were injected vaginally with four different doses of E. coli (103, 106, 1010, or 1011 colony forming units [CFU]) in 40 μL of nutrient broth or broth alone (control) on an embryonic day (E)15. Preterm birth (defined as delivery before E18.5) was monitored using live video. E. coli ascent kinetics were measured by staining the E. coli with lipophilic tracer DiD for visualization through intact tissue with an in vivo imaging system (IVIS) after inoculation. The E. coli were also directly visualized in reproductive tissues by staining the bacteria with carboxyfluorescein succinimidyl ester (CFSE) prior to administration and via immunohistochemistry (IHC) by staining tissues with anti-E. coli antibody. Each pup's amniotic fluid was cultured separately to determine the extent of microbial invasion of the intraamniotic cavity at different time points. Intraamniotic inflammation resulting from E. coli invasion was assessed with IHC for inflammatory markers (TLR-4, P-NF-κB) and neutrophil marker (Ly-6G) for chorioamnionitis at 6- and 24-h post-inoculation.

RESULTS

Vaginally administered E. coli resulted in preterm birth in a dose-dependent manner with higher doses causing earlier births. In ex vivo imaging and IHC detected uterine horns proximal to the cervix had increased E. coli compared to the distal uterine horns. E. coli were detected in the uterus, fetal membranes (FM), and placenta in a time-dependent manner with 6 hr having increased intensity of E. coli positive signals in pups near the cervix and in all pups at 24 hr. Similarly, E. coli grew from the cultures of amniotic fluid collected nearest to the cervix, but not from the more distal samples at 6 hr post-inoculation. At 24 hr, all amniotic fluid cultures regardless of distance from the cervix, were positive for E. coli. TLR-4 and P-NF-κB signals were more intense in the tissues where E. coli was present (placenta, FM and uterus), displaying a similar trend toward increased signal in proximal gestational sacs compared to distal at 6 hr. Ly-6G+ cells, used to confirm chorioamnionitis, were increased at 24 hr compared to 6 hr post-inoculation and control.

CONCLUSION

We report the development of mouse model of ascending infection and the associated inflammation of preterm birth. Clinically, these models can help to understand mechanisms of infection associated preterm birth, determine targets for intervention, or identify potential biomarkers that can predict a high-risk pregnancy status early in pregnancy.

Cervicovaginal microbiota and metabolome predict preterm birth risk in an ethnically diverse cohort

The syndrome of spontaneous preterm birth (sPTB) presents a challenge to mechanistic understanding, effective risk stratification, and clinical management. Individual associations between sPTB, self-reported ethnic ancestry, vaginal microbiota, metabolome, and innate immune response are known but not fully understood, and knowledge has yet to impact clinical practice. Here, we used multi–data type integration and composite statistical models to gain insight into sPTB risk by exploring the cervicovaginal environment of an ethnically heterogenous pregnant population (n = 346 women; n = 60 sPTB < 37 weeks’ gestation, including n = 27 sPTB < 34 weeks). Analysis of cervicovaginal samples (10–15⁺⁶ weeks) identified potentially novel interactions between risk of sPTB and microbiota, metabolite, and maternal host defense molecules. Statistical modeling identified a composite of metabolites (leucine, tyrosine, aspartate, lactate, betaine, acetate, and Ca²⁺) associated with risk of sPTB < 37 weeks (AUC 0.752). A combination of glucose, aspartate, Ca²⁺, Lactobacillus crispatus, and L. acidophilus relative abundance identified risk of early sPTB < 34 weeks (AUC 0.758), improved by stratification by ethnicity (AUC 0.835). Increased relative abundance of L. acidophilus appeared protective against sPTB < 34 weeks. By using cervicovaginal fluid samples, we demonstrate the potential of multi–data type integration for developing composite models toward understanding the contribution of the vaginal environment to risk of sPTB.

Prediction of preterm birth based on machine learning using bacterial risk score in cervicovaginal fluid

PROBLEM

Preterm birth (PTB) is a major cause of increased morbidity and mortality in newborns. The main cause of spontaneous PTB (sPTB) is the activation of an inflammatory response as a result of ascending genital tract infection. Despite various studies on the effects of the vaginal microbiome on PTB, a practical method for its clinical application has yet to be developed.

METHOD OF STUDY

In this case-control study, 94 Korean pregnant women with PTB (n = 38) and term birth (TB; n = 56) were enrolled. Their cervicovaginal fluid (CVF) was sampled, and a total of 10 bacteria were analyzed using multiplex quantitative real-time PCR (qPCR). The PTB and TB groups were compared, and a PTB prediction model was created using bacterial risk scores using machine learning techniques (decision tree and support vector machine). The predictive performance of the model was validated using random subsampling.

RESULTS

Bacterial risk scoring model showed significant differences (P < 0.001). The PTB risk was low when the Lactobacillus iners ratio was 0.812 or more. In groups with a ratio under 0.812, moderate and high risk was classified as a U. parvum ratio of 4.6 × 10^-3 . The sensitivity and specificity of the PTB prediction model using bacteria risk score were 71% and 59%, respectively, and 77% and 67%, respectively, when white blood cell (WBC) data were included.

CONCLUSION

Using machine learning, the bacterial risk score in CVF can be used to predict PTB.

Low immune activation in early pregnancy is associated with preterm but not small-for-gestational age delivery in HIV infected women initiating antiretroviral therapy in pregnancy: a PIMS case-control study in Cape Town, South Africa

Background

Mechanisms underlying an association between human immunodeficiency virus (HIV) or antiretroviral therapy (ART) during pregnancy with risk of preterm delivery (PTD) and small-for-gestational-age (SGA) remain unclear. We explored the association between cellular immune activation and PTD or SGA in women with HIV initiating ART during or before pregnancy.

Methods

Women with HIV enrolled at median 15 weeks’ gestation, were analyzed for immune markers, and matched on ART initiation timing (15 women initiated pre- and 15 during pregnancy). There were 30 PTD (delivery <37 weeks), 30 SGA (weight for age ≤10th percentile) cases, and 30 controls (term, weight for gestational age >25th percentile) as outcomes. Lymphocytes, monocytes, and dendritic cell populations and their activation status or functionality were enumerated by flow cytometry.

Results

PTD cases initiating ART in pregnancy showed decreased CD8⁺ T cell, monocyte, and dendritic cell activation; increased classical (CD14⁺CD16^–) and intermediate (CD14⁺CD16⁺) monocyte frequencies; and decreased inflammatory monocytes (CD14^dimCD16⁺) compared with SGA cases and term controls (all P < .05). Allowing for baseline viral load, the immune markers remained significantly associated with PTD but only in women initiating ART in pregnancy. Lower monocyte activation was predictive of PTD. TLR ligand-induced interferon-α and macrophage inflammatory protein-1β levels in monocytes were significantly lower in PTD women initiating ART in pregnancy.

Conclusion

Low immune activation, skewing toward anti-inflammatory monocytes, and lower monocyte cytokine production in response to TLR ligand stimulation were associated with PTD but not SGA among women initiating ART in, but not before, pregnancy, suggesting immune anergy to microbial stimulation as a possible underlying mechanism for PTD in women initiating ART in pregnancy.

Cervicovaginal natural antimicrobial expression in pregnancy and association with spontaneous preterm birth

There is much interest in the role of innate immune system proteins (antimicrobial peptides) in the inflammatory process associated with spontaneous preterm birth (sPTB). After promising pilot work, we aimed to validate the association between the antimicrobial peptides/proteins elafin and cathelicidin and sPTB. An observational cohort study of 405 women at high-risk, and 214 women at low-risk of sPTB. Protein concentrations of elafin and cathelicidin, and the enzyme human neutrophil elastase (HNE) were measured in over 1,000 cervicovaginal fluid (CVF) samples (10 to 24 weeks’ gestation). Adjusted CVF cathelicidin and HNE concentrations (but not elafin) were raised in high-risk women who developed cervical shortening and who delivered prematurely and were predictive of sPTB < 37 weeks, with an area under the curve (AUC) of 0.75 (95% CI 0.68 to 0.81) for cathelicidin concentration at 14 to 15⁺⁶ weeks. Elafin concentrations were affected by gestation, body mass index and smoking. CVF elafin in early pregnancy was modestly predictive of sPTB < 34 weeks (AUC 0.63, 0.56–0.70). Alterations in innate immune response proteins in early pregnancy are predictive of sPTB. Further investigation is warranted to understand the drivers for this, and their potential to contribute towards clinically useful prediction techniques.

Cervicovaginal microbial communities deficient in Lactobacillus species are associated with second trimester short cervix

BACKGROUND

The cervix functions as a barrier to ascending pathogens in pregnancy. Short cervical length and lack of cervicovaginal Lactobacillus species are risk factors for spontaneous preterm birth; however, whether they interact to increase risk remains unknown.

OBJECTIVE

We sought to examine the relationship between cervicovaginal microbiota and short cervix as well as their combined impact on spontaneous preterm birth risk.

STUDY DESIGN

This was a secondary analysis of a prospective nested, case-control pregnancy study. Cervical swabs were collected between 16 and 20 weeks of gestation. Cervical length was measured per standard clinical care during a clinically indicated ultrasound at approximately 20 weeks of gestation. Cervicovaginal microbiota were analyzed with 16S ribosomal RNA gene sequencing and classified into community state types among 67 cases of spontaneous preterm birth, 47 cases of medically indicated preterm birth, and 358 cases of term births. Logistic regression was used to model associations of community state type IV, a community characterized by a paucity of Lactobacillus species and a wide array of anaerobic bacteria, and short cervix (<25 mm) as well as to model the association of a combination of short cervix and community state type IV with the odds of spontaneous preterm birth.

RESULTS

Among the 472 women in the data set, there were 38 with short cervix (8.1%) and 177 with community state type IV (37.5%). Short cervix was associated with spontaneous preterm birth (adjusted odds ratio, 15.59; 95% confidence interval, 6.77-35.92). Women with community state type IV had higher odds of short cervix (adjusted odds ratio, 2.17; 95% confidence interval, 1.04-4.53) as well as spontaneous preterm birth (adjusted odds ratio, 1.97; 95% confidence interval, 1.06-3.65). While the interaction of community state type IV and short cervix was not significant (P = .771), women with both short cervix and community state type IV (n = 20) had higher odds of spontaneous preterm birth compared with women with both normal cervical length and community state types I, II, III, or V (n = 277) (adjusted odds ratio, 21.8; 95% confidence interval, 6.78-70.2).

CONCLUSION

Community state type IV, characterized by a diverse set of strict and facultative anaerobes and a paucity of Lactobacillus species, is associated with increased odds of short cervix. Women with both community state type IV and short cervix have higher odds of spontaneous preterm birth than women with either factor alone. Determining the cascade of events leading to premature cervical shortening, including dysbiosis, may be critical in preventing spontaneous preterm birth.