Gut microbiota dysbiosis in preeclampsia patients in the second and third trimesters

Indole-3-lactic acid derived from tryptophan metabolism promotes trophoblast migration and invasion by activating the AhR/VCAN pathway

BACKGROUND

Preeclampsia (PE) is a life-threatening condition that is unique to human pregnancy, and it is a leading cause of maternal and neonatal morbidity and mortality. Currently, the only definitive treatment for PE is delivery of the placenta. Several studies have suggested that the gut microbiota and its derived metabolites may be associated with PE. Our previous work indicated that the level of indole-3-lactic acid (ILA), which is a metabolite derived from tryptophan (Trp) metabolism in the gut, is increased in PE patients. However, the effects of ILA on trophoblast function and its underlying mechanisms remain largely unknown.

METHODS

Transwell assays were conducted to assess the effects of ILA on trophoblast migration and invasion. Moreover, the aryl hydrocarbon receptor (AhR) signaling pathway was examined by qRT-PCR, western blotting and siRNA transfection. Additionally, RNA-seq analysis was performed to explore the mechanism underlying the ILA-mediated effects on trophoblast function. Finally, in vivo trophoblast invasion was evaluated through immunohistochemical analysis.

RESULTS

Our data demonstrated that ILA promoted HTR-8/SVneo cell migration and invasion through AhR signaling pathway activation. Mechanistically, VCAN upregulation played a key role in mediating the effects of ILA on trophoblasts after AhR activation. Notably, ILA supplementation improved spiral artery remodeling and increased trophoblast invasion in PE-like mice, primarily by increasing VCAN levels.

CONCLUSIONS

These data strongly suggest that elevated ILA in PE serve as a protective mechanism against trophoblast dysfunction. Therefore, we propose that ILA may be a novel and promising therapeutic approach for treating PE by enhancing trophoblast functions.

Unraveling the role of the gut microbiome in pregnancy disorders: insights and implications

The gut microbiota is the collective term for the microorganisms that reside in the human gut. In recent years, advances in sequencing technology and bioinformatics gradually revealed the role of gut microbiota in human health. Dramatic changes in the gut microbiota occur during pregnancy due to hormonal and dietary changes, and these changes have been associated with certain gestational diseases such as preeclampsia (PE) and gestational diabetes mellitus (GDM). Modulation of gut microbiota has also been proposed as a potential treatment for these gestational diseases. The present article aims to review current reports on the association between gut microbiota and gestational diseases, explore possible mechanisms, and discuss the potential of probiotics in gestational diseases. Uncovering the link between gut microbiota and gestational diseases could lead to a new therapeutic approach.

Association between gut microbiota and perinatal depression and anxiety among a pregnancy cohort in Hunan, China

BACKGROUND

Perinatal depression and anxiety pose significant risks to maternal health and may lead to suicide. The gut microbiota may play a crucial role in perinatal depression and anxiety. However, the relationship between the alterations in gut microbiota and perinatal depression and anxiety remains unclear. This study aimed to investigate the dynamic changes of gut microbiota over various perinatal stages and their associations with perinatal depression and anxiety symptoms, especially suicide ideation.

METHODS

A total of 177 pregnant and 19 postpartum women were recruited in this study, with 48 of them participating longitudinally. Maternal depression and anxiety symptoms were assessed using the Edinburgh Postnatal Depression Scale (EPDS), 9-item Patient Health Questionnaire (PHQ-9), and 7-item Generalized Anxiety Disorder Scale (GAD-7). Fecal samples collected during the perinatal period were analyzed using 16S rRNA gene sequencing.

RESULTS

Significant changes in microbial diversity and multi-taxonomic levels were observed during pregnancy. The random forest regression model showed significant associations of some gut microbial features with depression and anxiety symptoms. Several genera were significantly associated with gestation age and perinatal depression and anxiety, such as Akkermansia, Bifidobacterium and Streptococcus. In addition, Erysipelotrichaceae_UCG-003 and Eubacterium_hallii_group were positively associated with suicidal ideation. The glycine biosynthesis pathway might act as a mediator between Eubacterium_hallii_group and suicidal ideation (ab = 3.27, p < 0.05).

CONCLUSION

The gut microbiota undergoes a programmed shift during pregnancy, which may play a critical role in perinatal depression and anxiety. Our findings underscore the impact of certain bacterial genera and metabolic pathways on perinatal mental health, which may help to develop new diagnostic tools and targeted interventions to reduce perinatal mental disorders and improve the outcomes for both mothers and infants.

Nutraceuticals as Modulators of Molecular Placental Pathways: Their Potential to Prevent and Support the Treatment of Preeclampsia

Preeclampsia (PE) is a serious condition characterized by new-onset hypertension and proteinuria or organ dysfunction after the 20th week of gestation, making it a leading cause of maternal and fetal mortality worldwide. Despite extensive research, significant gaps remain in understanding the mechanisms underlying PE, contributing to the ineffectiveness of current prevention and treatment strategies. Consequently, premature cesarean sections often become the primary intervention to safeguard maternal and fetal health. Emerging evidence indicates that placental insufficiency, driven by molecular disturbances, plays a central role in the development of PE. Additionally, the maternal microbiome may be implicated in the pathomechanism of preeclampsia by secreting metabolites that influence maternal inflammation and oxidative stress, thereby affecting placental health. Given the limitations of pharmaceuticals during pregnancy due to potential risks to fetal development and concerns about teratogenic effects, nutraceuticals may provide safer alternatives. Nutraceuticals are food products or dietary supplements that offer health benefits beyond basic nutrition, including plant extracts or probiotics. Their historical use in traditional medicine has provided valuable insights into their safety and efficacy, including for pregnant women. This review will examine how the adoption of nutraceuticals can enhance dysregulated placental pathways, potentially offering benefits in the prevention and treatment of preeclampsia.

Scoping Review of Microbiota Dysbiosis and Risk of Preeclampsia

Limited studies have investigated the role of the microbiota in hypertensive disorders of pregnancy (HDP), particularly preeclampsia, which often results in preterm birth. We evaluated 23 studies that explored the relationship between gut, vaginal, oral, or placental microbiotas and HDP. Scopus, ProQuest Health Research Premium Collection, ProQuest Nursing & Allied Health Database, EBSCO, and Ovid were searched for relevant literature. Majority (18) of studies focused on the gut microbiota, and far fewer examined the oral cavity (3), vagina (3), and placenta (1). One study examined the gut, oral, and vaginal microbiotas. The consensus highlights a potential role for microbiota dysbiosis in preeclampsia and HDP. Especially in the third trimester, preeclampsia is associated with gut dysbiosis-deficient in beneficial species of Akkermansia, Bifidobacterium, and Coprococcus but enriched with pathogenic Campylobacterota and Candidatus Saccharibacteria, with low community α-diversity. Similarly, the preeclamptic vaginal and oral microbiotas are enriched with bacterial vaginosis and periodontal disease-associated species, respectively. The trend is also observed in the placenta, which is colonized by gastrointestinal, respiratory tract, and periodontitis-related pathogens. Consequently, a chronic proinflammatory state that adversely impacts placentation is implicated. These observations however require more mechanistic studies to establish the timing of the preceding immune dysfunction and any causality.

The Hidden Relationship between Intestinal Microbiota and Immunological Modifications in Preeclampsia Pathogenesis

Preeclampsia is a multifactorial gestational syndrome characterized by increased blood pressure during pregnancy associated with multiorgan involvement. The impact of this disease on maternal and neonatal health is significant, as it can lead to various fetal comorbidities and contribute to the development of maternal comorbidities later in life. Consistent evidence has shown that the microbiota acts as a regulator of the immune system, and it may, therefore, influence the development of preeclampsia by modulating immune factors. This narrative review aims to investigate the role of the immune system in the pathogenesis of preeclampsia and to summarize the most recent literature on the possible link between preeclampsia and alterations in the intestinal microbiota. To this end, we conducted a literature search, aiming to perform a narrative review, on PubMed and Embase from January 1990 to March 2024, focusing on the latest studies that highlight the main differences in microbial composition between patients with and without preeclampsia, as well as the effects of microbial metabolites on the immune system. From the review of 28 studies assessing the intestinal microbiota in preeclamptic women, preeclampsia could be associated with a state of dysbiosis. Moreover, these patients showed higher plasmatic levels of endotoxin, pro-inflammatory cytokines, and T helper 17 cells; however, the findings on specific microbes and metabolites that could cause immune imbalances in preeclampsia are still preliminary.

Preeclampsia: A comprehensive review

Preeclampsia (PE) is a life-threatening disease of pregnancy and a prominent cause of neonatal and maternal mortality and morbidity. PE affects approximately 5-10% of pregnancies worldwide, posing significant risks to perinatal and maternal health. It is characterized by a variety of interconnected pathological cascades contributing to the stimulation of intravascular inflammation, oxidative stress (OS), endothelial cell activation, and syncytiotrophoblast stress that converge on a common pathway, ultimately resulting in disease progression. The present study was designed and executed to review the existing scientific literature, specifically focusing on the etiology (gestational diabetes mellitus and maternal obesity, insulin resistance, metabolic syndrome, maternal infection, periodontal disease, altered microbiome, and genetics), clinical presentations (hypertension, blood disorders, proteinuria, hepatic dysfunction, renal dysfunction, pulmonary edema, cardiac dysfunction, fetal growth restrictions, and eclampsia), therapeutic clinical biomarkers (creatinine, albuminuria, and cystatin C) along with their associations and mechanisms in PE. In addition, this study provides insights into the potential of nanomedicines for targeting these mechanisms for PE management and treatment. Inflammation, OS, proteinuria, and an altered microbiome are prominent biomarkers associated with progression and PE-related pathogenesis. Understanding the molecular mechanisms, exploring suitable markers, targeted interventions, comprehensive screening, and holistic strategies are critical to decreasing the incidence of PE and promoting maternal-fetal well-being. The present study comprehensively reviewed the etiology, clinical presentations, therapeutic biomarkers, and preventive potential of nanomedicines in the treatment and management of PE.

Spatiotemporal patterns of the pregnancy microbiome and links to reproductive disorders

The microbiome of females undergoes extensive remodeling during pregnancy, which is likely to have an impact on the health of both mothers and offspring. Nevertheless, large-scale integrated investigations characterizing microbiome dynamics across key body habitats are lacking. Here, we performed an extensive meta-analysis that compiles and analyzes microbiome profiles from  >10,000 samples across the gut, vagina, and oral cavity of pregnant women from diverse geographical regions. We have unveiled unexpected variations in the taxonomic, functional, and ecological characteristics of microbial communities throughout the course of pregnancy. The gut microbiota showed distinct trajectories between Western and non-Western populations. The vagina microbiota exhibited fluctuating transitions at the genus level across gestation, while the oral microbiota remained relatively stable. We also identified distinctive microbial signatures associated with prevalent pregnancy-related disorders, including opposite variations in the oral and gut microbiota of patients with gestational diabetes and disrupted microbial networks in preterm birth. This study establishes a comprehensive atlas of the pregnancy microbiome by integrating multidimensional datasets and offers foundational insights into the intricate interplay between microbes and host factors that underlie reproductive health.

Microbiome in Female Reproductive Health: Implications for Fertility and Assisted Reproductive Technologies

The microbiome plays a critical role in the process of conception and the outcomes of pregnancy. Disruptions in microbiome homeostasis in women of reproductive age can lead to various pregnancy complications, which significantly impact maternal and fetal health. Recent studies have associated the microbiome in the female reproductive tract (FRT) with assisted reproductive technology (ART) outcomes, and restoring microbiome balance has been shown to improve fertility in infertile couples. This review provides an overview of the role of the microbiome in female reproductive health, including its implications for pregnancy outcomes and ARTs. Additionally, recent advances in the use of microbial biomarkers as indicators of pregnancy disorders are summarized. A comprehensive understanding of the characteristics of the microbiome before and during pregnancy and its impact on reproductive health will greatly promote maternal and fetal health. Such knowledge can also contribute to the development of ARTs and microbiome-based interventions.

An altered gut microbiome in pre-eclampsia: cause or consequence

Hypertensive disorders of pregnancy, including pre-eclampsia, are a leading cause of serious and debilitating complications that affect both the mother and the fetus. Despite the occurrence and the health implications of these disorders there is still relatively limited evidence on the molecular underpinnings of the pathophysiology. An area that has come to the fore with regard to its influence on health and disease is the microbiome. While there are several microbiome niches on and within the body, the distal end of the gut harbors the largest of these impacting on many different systems of the body including the central nervous system, the immune system, and the reproductive system. While the role of the microbiome in hypertensive disorders, including pre-eclampsia, has not been fully elucidated some studies have indicated that several of the symptoms of these disorders are linked to an altered gut microbiome. In this review, we examine both pre-eclampsia and microbiome literature to summarize the current knowledge on whether the microbiome drives the symptoms of pre-eclampsia or if the aberrant microbiome is a consequence of this condition. Despite the paucity of studies, obvious gut microbiome changes have been noted in women with pre-eclampsia and the individual symptoms associated with the condition. Yet further research is required to fully elucidate the role of the microbiome and the significance it plays in the development of the symptoms. Regardless of this, the literature highlights the potential for a microbiome targeted intervention such as dietary changes or prebiotic and probiotics to reduce the impact of some aspects of these disorders.

Maternal gut microbiota in the health of mothers and offspring: from the perspective of immunology

Due to the physiological alteration during pregnancy, maternal gut microbiota changes following the metabolic processes. Recent studies have revealed that maternal gut microbiota is closely associated with the immune microenvironment in utero during pregnancy and plays a vital role in specific pregnancy complications, including preeclampsia, gestational diabetes, preterm birth and recurrent miscarriages. Some other evidence has also shown that aberrant maternal gut microbiota increases the risk of various diseases in the offspring, such as allergic and neurodevelopmental disorders, through the immune alignment between mother and fetus and the possible intrauterine microbiota. Probiotics and the high-fiber diet are effective inventions to prevent mothers and fetuses from diseases. In this review, we summarize the role of maternal gut microbiota in the development of pregnancy complications and the health condition of future generations from the perspective of immunology, which may provide new therapeutic strategies for the health management of mothers and offspring.

The gut microbiota composition and metabolites are different in women with hypertensive disorders of pregnancy and normotension: A pilot study

INTRODUCTION

Hypertensive disorders of pregnancy (HDP) are one of the main causes of perinatal morbidity. Gut microbiota influences host inflammatory pathways, glucose, and lipid metabolism. However, there is a lack of studies available on gut microbiota in HDP.

OBJECTIVES

We investigate the mechanistic and pathogenic role of microbiota in the development of HDP, and want to treat HDP with gut microbiota.

METHODS

We performed a case-control study to compare fecal samples of HDP and normotensive pregnant women by 16S ribosomal RNA sequencing. Fecal samples, collected from pregnant women, were divided into groups P and C (pregnant women with HDP and normotension, respectively). There were six pregnant women in group P and nine pregnant women in group C. Age of pregnant women is from 18 to 40 years and gestational age is from 27 to 40 weeks. DNA was extracted from fecal samples; a gene library was constructed and analyzed using bioinformatics. Finally, we determined the changes in the microbiome by alpha diversity, beta diversity, classification abundance, and taxonomic composition analyses.

RESULTS

Escherichia (10.48% in group P and 0.61% in group C) was the dominant bacterium in HDP patients by classification abundance analysis, which can lead to the development of preeclampsia through inflammatory response. We found that pregnant women with HDP had higher abundance of Rothia (p = 0.04984), Actinomyces (p = 0.02040), and Enterococcus (p = 0.04974) and lower abundance of Coprococcus (p = 0.04955) than pregnant women with normotension for the first time by taxonomic composition analysis. Based on the Kyoto Encyclopedia of Genes and Genomes database analysis, physiological and biochemical functions of HDP patients were significantly weakened, especially in energy metabolism.

CONCLUSIONS

We found the effect of changes in gut microbiota on the development of HDP. In comparison with group C, group P contained more harmful bacteria and less beneficial bacteria, which are associated with HDP. Our research further provides a basis for a clinical application for HDP treatment using antibiotics and probiotic supplementation.

The effects of synbiotic supplementation on blood pressure and other maternal outcomes in pregnant mothers with mild preeclampsia: a triple-blinded randomized controlled trial

INTRODUCTION

Preeclampsia affects a significant percentage of pregnancies which is a leading cause of premature birth. Probiotics have the potential to affect inflammatory factors, and oxidative stress, which are linked to the development of preeclampsia. The study aimed to compare the effect of synbiotic and placebo on blood pressure and pregnancy duration as primary outcomes, and other pregnancy outcomes.

METHODS

This study comprised 128 pregnant women with mild preeclampsia and gestational ages exceeding 24 weeks who were referred to the high-risk pregnancy clinic. It was a randomized, controlled, phase III, triple-blinded clinical experiment. The intervention and control groups were distributed to the participants at random. Intervention group received one oral synbiotic capsule, and control group received placebo daily until delivery. Based on gestational age at the time of diagnosis, preeclampsia was stratificated as early (< 34 weeks) or late (≥ 34 weeks). Data obtained from questionnaires, and biochemical serum factors were analyzed using SPSS software version 23 software.

RESULTS

With the exception of the history of taking vitamin D3, there were no statistically significant variations in socio-demographic variables between the research groups. After the intervention, the means of systolic blood pressure (adjusted mean difference: -13.54, 95% CI: -5.01 to -22.07), and diastolic blood pressure (adjusted mean difference: -10.30, 95% CI: -4.70 to -15.90) were significantly lower in the synbiotic-supplemented group than in the placebo group. Compared to the placebo group, the incidence of severe PE (p < 0.001), proteinuria (p = 0.044), and mean serum creatinine level (p = 0.005) significantly declined in the synbiotic-supplemented group after the intervention. However, our analysis found no significant association for other outcomes.

CONCLUSION

Based on our results, synbiotic had beneficial effects on some pregnancy outcomes. Further studies with larger samples are needed to verify the advantages of synbiotic supplementation for high-risk pregnancies, particularly with regards to higher doses, and longer intervention periods.

TRIAL REGISTRATION

IRCT20110606006709N20.

MAMI: a comprehensive database of mother-infant microbiome and probiotic resources

Extensive evidence has demonstrated that the human microbiome and probiotics confer great impacts on human health, particularly during critical developmental stages such as pregnancy and infancy when microbial communities undergo remarkable changes and maturation. However, a major challenge in understanding the microbial community structure and interactions between mothers and infants lies in the current lack of comprehensive microbiome databases specifically focused on maternal and infant health. To address this gap, we have developed an extensive database called MAMI (Microbiome Atlas of Mothers and Infants) that archives data on the maternal and neonatal microbiome, as well as abundant resources on edible probiotic strains. By leveraging this resource, we can gain profound insights into the dynamics of microbial communities, contributing to lifelong wellness for both mothers and infants through precise modulation of the developing microbiota. The functionalities incorporated into MAMI provide a unique perspective on the study of the mother-infant microbiome, which not only advance microbiome-based scientific research but also enhance clinical practice. MAMI is publicly available at https://bioinfo.biols.ac.cn/mami/.

The Dynamic Changes in the Composition and Diversity of Vaginal Microbiota in Women of Different Pregnancy Periods

The vaginal microbiota undergoes subtle changes during pregnancy, which may affect different pregnancy responses. This study used the Illumina MiSeq high-throughput sequencing method to analyze the 16S rRNA gene amplicons of pregnant women and the vaginal microbiota structure of pregnant women at different pregnancy periods. There were a total of 15 pregnant women, with 45 samples were taken from these women, within half a year before becoming pregnant, in the last trimester, and 42 days postpartum. Before and after pregnancy, the female vaginal microbiota was mainly composed of Firmicutes, followed by Actinobacteriota and Proteobacteria. The abundance of Lactobacillus was relatively high. The α-diversity and microbial abundance were relatively low, and there was no significant difference in microbial composition between the two. After childbirth, the diversity and abundance of women's vaginal bacterial communities were higher, with a decrease in the number of Firmicutes and a higher abundance of Actinobacteria, Proteobacteria, and Bacteroidota. There was a significant difference in the microbial community structure before and after pregnancy. This study showed that the microbiota structure of the vagina of pregnant women was similar to before pregnancy, but after childbirth, there were significant changes in the microbiota of the vagina, with a decrease in the number of probiotics and an increase in the number of harmful bacteria, increasing the risk of illness.

Research progress on the correlation between gut microbiota and preeclampsia: microbiome changes, mechanisms and treatments

Preeclampsia is a specific disease during pregnancy and is a significant factor in the increased mortality in perinatal women. Gut microbiota, an intricate and abundant microbial community in the digestive tract, is crucial for host metabolism, immunity, and nutrient absorption. The onset and progression of preeclampsia are closely correlated with the changes in maternal gut microbiota. Research purpose was to compile the existing bits of present scientific data and to close the gap in the knowledge of changes in gut microbiota in preeclampsia and their association with preeclampsia. We searched studies from two electronic databases (PubMed and Web of Science) included from 2014 to 2023. This review is divided into three parts. In the first part, the author elaborates longitudinal differences of maternal gut microbiota during different gestation periods. In the second part, we discuss that gut microbiota can lead to the occurrence of preeclampsia by systemic immune response, influencing the release of active peptides, short-chain fatty acids, trimethylamine-N-oxide (TMAO) and other metabolites, vascular factors and Microorganism-immune axis. In the third part, we proposed that a high-fiber diet combined with drugs and microecological regulators may be therapeutic in enhancing or preventing the emergence and evolution of preeclampsia, which needs further exploration. Although the pathogenesis of preeclampsia is still nebulous and there is no clear and valid clinical treatment, our study provides new ideas for the pathogenesis, prevention and treatment of preeclampsia.

The role of short-chain fatty acids produced by gut microbiota in the regulation of pre-eclampsia onset

Background

Preeclampsia (PE) is a common pregnancy-related disorder characterized by disrupted maternal-fetal immune tolerance, involving diffuse inflammatory responses and vascular endothelial damage. Alterations in the gut microbiota (GM) during pregnancy can affect intestinal barrier function and immune balance.

Aims and purpose

This comprehensive review aims to investigate the potential role of short-chain fatty acids (SCFAs), essential metabolites produced by the GM, in the development of PE. The purpose is to examine their impact on colonic peripheral regulatory T (Treg) cells, the pathogenic potential of antigen-specific helper T (Th) cells, and the inflammatory pathways associated with immune homeostasis.

Key insights

An increasing body of evidence suggests that dysbiosis in the GM can lead to alterations in SCFA levels, which may significantly contribute to the development of PE. SCFAs enhance the number and function of colonic Treg cells, mitigate the pathogenic potential of GM-specific Th cells, and inhibit inflammatory progression, thereby maintaining immune homeostasis. These insights highlight the potential significance of GM dysregulation and SCFAs produced by GM in the pathogenesis of PE. While the exact causes of PE remain elusive, and definitive clinical treatments are lacking, the GM and SCFAs present promising avenues for future clinical applications related to PE, offering a novel approach for prophylaxis and therapy.

Prenatal physical activity and the gut microbiota of pregnant women: results from a preliminary investigation

PURPOSE

To determine whether physical activity (PA), specifically meeting the recommended 150 minutes of moderate-intensity PA per week, is associated with gut microbiota composition in pregnant women.

METHODS

In an ongoing birth cohort study, questions from the Behavioral Risk Factor Surveillance System, which provides data on PA variables, were used to determine whether pregnant women met or exceeded the PA recommendations. To profile the composition of gut bacterial microbiota, 16S rRNA sequencing was performed on stool samples obtained from pregnant women. Differences in alpha diversity metrics (richness, Pielou's evenness, and Shannon's diversity) according to PA were determined using linear regression, whereas beta diversity relationships (Canberra and Bray-Curtis) were assessed using Permutational multivariate analysis of variance (PERMANOVA). Differences in relative taxon abundance were determined using DESeq2.

RESULTS

The complete analytical sample included 23 women that were evaluated for both PA and 16S rRNA sequencing data (median age [Q1; Q3] = 30.5 [26.6; 34.0] years; 17.4% Black), and 11 (47.8%) met or exceeded the PA recommendations. Meeting or exceeding the PA recommendations during pregnancy was not associated with gut microbiota richness, evenness, or diversity, but it was related to distinct bacterial composition using both Canberra (p = 0.005) and Bray-Curtis (p = 0.022) distances. Significantly lower abundances of Bacteroidales, Bifidobacteriaceae, Lactobacillaceae, and Streptococcaceae were observed in women who met or exceeded the PA recommendations (all false discovery rates adjusted, p < 0.02).

CONCLUSION

Pregnant women who met or exceeded the PA recommendations showed altered gut microbiota composition. This study forms the basis for future studies on the impact of PA on gut microbiota during pregnancy.

Evaluating Current Molecular Techniques and Evidence in Assessing Microbiome in Placenta-Related Health and Disorders in Pregnancy

The microbiome is of great interest due to its potential influence on the occurrence and treatment of some human illnesses. It may be regarded as disruptions to the delicate equilibrium that humans ordinarily maintain with their microorganisms or the microbiota in their environment. The focus of this review is on the methodologies and current understanding of the functional microbiome in pregnancy outcomes. We present how novel techniques bring new insights to the contemporary field of maternal-fetal medicine with a critical analysis. The maternal microbiome in late pregnancy has been extensively studied, although data on maternal microbial changes during the first trimester are rare. Research has demonstrated that, in healthy pregnancies, the origin of the placental microbiota is oral (gut) rather than vaginal. Implantation, placental development, and maternal adaptation to pregnancy are complex processes in which fetal and maternal cells interact. Microbiome dysbiosis or microbial metabolites are rising as potential moderators of antenatal illnesses related to the placenta, such as fetal growth restriction, preeclampsia, and others, including gestational diabetes and preterm deliveries. However, because of the presence of antimicrobial components, it is likely that the bacteria identified in placental tissue are (fragments of) bacteria that have been destroyed by the placenta's immune cells. Using genomic techniques (metagenomics, metatranscriptomics, and metaproteomics), it may be possible to predict some properties of a microorganism's genome and the biochemical (epigenetic DNA modification) and physical components of the placenta as its environment. Despite the results described in this review, this subject needs further research on some major and crucial aspects. The phases of an in utero translocation of the maternal gut microbiota to the fetus should be explored. With a predictive knowledge of the impacts of the disturbance on microbial communities that influence human health and the environment, genomics may hold the answer to the development of novel therapies for the health of pregnant women.

Gut Microbiota Dysbiosis and Increased NLRP3 Levels in Patients with Pregnancy-Induced Hypertension

Pregnancy-induced hypertension (PIH) is one of the most common diseases, causing high maternal morbidity and mortality. However, the correlation of gut microbiota in PIH has not been reported. Our aim was to characterize the intestinal microbiota of patients with PIH compared with healthy people. We analyzed and compared the gut microbiota communities in the feces of 28 PIH patients with pregnancy(not pre-pregnancy) body mass index (including height and weight)-matched healthy controls using 16S rRNA gene sequencing and then investigate the relationships among gut microbiota, cytokines, and PIH. Compared with the healthy group, microbial α diversity was lower in the PIH group, but not statistically significant different. At the phylum level, Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria exhibited obvious differences between the PIH and control groups. LEfSe analysis found 33 differentially abundant taxa between the two groups. The production of pro-inflammatory cytokines in PIH serum or placenta tissues was higher than that of the control group. In addition to alterations in gut microbiota composition, we also found that the Bac_Prevotellaceae, Pre_Prevotella bacteria were positively correlated with NLRP3 level, but negatively correlated with Bac_Bacteroidaceae, Bac_Bacteroides. PIH patients had gut microbiota dysbiosis and increased NLRP3 levels, which will lead to a better understanding of the relationship between the gut microbiota and PIH.

Comparison of Fecal Microbiota Communities between Primiparous and Multiparous Cows during Non-Pregnancy and Pregnancy

Imbalances in the gut microbiota composition may lead to several reproductive disorders and diseases during pregnancy. This study investigates the fecal microbiome composition between primiparous and multiparous cows during non-pregnancy and pregnancy to analyze the host-microbial balance at different stages. The fecal samples obtained from six cows before their first pregnancy (BG), six cows during their first pregnancy (FT), six open cows with more than three lactations (DCNP), and six pregnant cows with more than three lactations (DCP) were subjected to 16S rRNA sequencing, and a differential analysis of the fecal microbiota composition was performed. The three most abundant phyla in fecal microbiota were Firmicutes (48.68%), Bacteroidetes (34.45%), and Euryarchaeota (15.42%). There are 11 genera with more than 1.0% abundance at the genus level. Both alpha diversity and beta diversity showed significant differences among the four groups (p < 0.05). Further, primiparous women were associated with a profound alteration of the fecal microbiota. The most representative taxa included Rikenellaceae_RC9_gut_group, Prevotellaceae_UCG_003, Christensenellaceae_R_7_group, Ruminococcaceae UCG-005, Ruminococcaceae UCG-013, Ruminococcaceae UCG-014, Methanobrevibacter, and [Eubacterium] coprostanoligenes group, which were associated with energy metabolism and inflammation. The findings indicate that host-microbial interactions promote adaptation to pregnancy and will benefit the development of probiotics or fecal transplantation for treating dysbiosis and preventing disease development during pregnancy.

Necrotizing Enterocolitis: The Role of Hypoxia, Gut Microbiome, and Microbial Metabolites

Necrotizing enterocolitis (NEC) is a life-threatening disease that predominantly affects very low birth weight preterm infants. Development of NEC in preterm infants is accompanied by high mortality. Surgical treatment of NEC can be complicated by short bowel syndrome, intestinal failure, parenteral nutrition-associated liver disease, and neurodevelopmental delay. Issues surrounding pathogenesis, prevention, and treatment of NEC remain unclear. This review summarizes data on prenatal risk factors for NEC, the role of pre-eclampsia, and intrauterine growth retardation in the pathogenesis of NEC. The role of hypoxia in NEC is discussed. Recent data on the role of the intestinal microbiome in the development of NEC, and features of the metabolome that can serve as potential biomarkers, are presented. The Pseudomonadota phylum is known to be associated with NEC in preterm neonates, and the role of other bacteria and their metabolites in NEC pathogenesis is also discussed. The most promising approaches for preventing and treating NEC are summarized.

The effect of gut microbiota dysbiosis on patients with preeclampsia

Purpose

To compare the difference of gut microbiota between preeclampsia (PE) and healthy normal pregnant women, providing new therapeutic strategy for preeclampsia.

Methods

Forty-one PE patients and 45 age- and pre-pregnancy body mass index- matched healthy controls were enrolled from Nov 2021 to May 2022 in this retrospective case-control study. Fecal microbiota was detected by 16S rRNA gene sequencing, followed by bioinformatics analysis including microbial α diversity, microbial β diversity, and linear discriminant analysis effect size (LEfSe) analysis. Serum inflammatory factors were also detected and compared between the two groups.

Results

There were significant differences in Bacteroidetes (2.68% in PE patients vs 11.04% in healthy controls, P < 0.001), Proteobacteria (4.04% in PE patients vs 1.22% in healthy controls, P = 0.041), and Fusobacteria (1.07% in PE patients vs 0.01% in healthy controls, P = 0.042) between the two groups at the phylum level. Microbial α diversity was lower in PE patients than that in healthy controls. In addition, there was significant difference in microbial β diversity between the two groups. LEfSe analysis showed that there are 24 different taxa between the two groups. The levels of proinflammatory factors including serum tumor necrosis factor-α and Interleukin-6 were statistically significant higher in PE patients than those in healthy controls (both P < 0.001), while there were no significant differences in the levels of serum anti-inflammatory factors including Interleukin-4 and Interleukin-10 between the two groups (P = 0.234 and P = 0.096, respectively).

Conclusion

PE patients demonstrated gut microbiota disturbances and increasing serum proinflammatory factors, leading to a better understanding of the relationship between the gut microbiota dysbiosis and PE.

Association between gut microbiota and preeclampsia-eclampsia: a two-sample Mendelian randomization study

BACKGROUND

Several recent observational studies have reported that gut microbiota composition is associated with preeclampsia. However, the causal effect of gut microbiota on preeclampsia-eclampsia is unknown.

METHODS

A two-sample Mendelian randomization study was performed using the summary statistics of gut microbiota from the largest available genome-wide association study meta-analysis (n=13,266) conducted by the MiBioGen consortium. The summary statistics of preeclampsia-eclampsia were obtained from the FinnGen consortium R7 release data (5731 cases and 160,670 controls). Inverse variance weighted, maximum likelihood, MR-Egger, weighted median, weighted model, MR-PRESSO, and cML-MA were used to examine the causal association between gut microbiota and preeclampsia-eclampsia. Reverse Mendelian randomization analysis was performed on the bacteria that were found to be causally associated with preeclampsia-eclampsia in forward Mendelian randomization analysis. Cochran's Q statistics were used to quantify the heterogeneity of instrumental variables.

RESULTS

Inverse variance weighted estimates suggested that Bifidobacterium had a protective effect on preeclampsia-eclampsia (odds ratio = 0.76, 95% confidence interval: 0.64-0.89, P = 8.03 × 10^-4). In addition, Collinsella (odds ratio = 0.77, 95% confidence interval: 0.60-0.98, P = 0.03), Enterorhabdus (odds ratio = 0.76, 95% confidence interval: 0.62-0.93, P = 8.76 × 10^-3), Eubacterium (ventriosum group) (odds ratio = 0.76, 95% confidence interval: 0.63-0.91, P = 2.43 × 10^-3), Lachnospiraceae (NK4A136 group) (odds ratio = 0.77, 95% confidence interval: 0.65-0.92, P = 3.77 × 10^-3), and Tyzzerella 3 (odds ratio = 0.85, 95% confidence interval: 0.74-0.97, P = 0.01) presented a suggestive association with preeclampsia-eclampsia. According to the results of reverse MR analysis, no significant causal effect of preeclampsia-eclampsia was found on gut microbiota. No significant heterogeneity of instrumental variables or horizontal pleiotropy was found.

CONCLUSIONS

This two-sample Mendelian randomization study found that Bifidobacterium was causally associated with preeclampsia-eclampsia. Further randomized controlled trials are needed to clarify the protective effect of probiotics on preeclampsia-eclampsia and their specific protective mechanisms.

Gut Microbiota Associated with Gestational Health Conditions in a Sample of Mexican Women

Gestational diabetes (GD), pre-gestational diabetes (PD), and pre-eclampsia (PE) are morbidities affecting gestational health which have been associated with dysbiosis of the mother's gut microbiota. This study aimed to assess the extent of change in the gut microbiota diversity, short-chain fatty acids (SCFA) production, and fecal metabolites profile in a sample of Mexican women affected by these disorders. Fecal samples were collected from women with GD, PD, or PE in the third trimester of pregnancy, along with clinical and biochemical data. Gut microbiota was characterized by high-throughput DNA sequencing of V3-16S rRNA gene libraries; SCFA and metabolites were measured by High-Pressure Liquid Chromatography (HPLC) and (Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR MS), respectively, in extracts prepared from feces. Although the results for fecal microbiota did not show statistically significant differences in alfa diversity for GD, PD, and PE concerning controls, there was a difference in beta diversity for GD versus CO, and a high abundance of Proteobacteria, followed by Firmicutes and Bacteroidota among gestational health conditions. DESeq2 analysis revealed bacterial genera associated with each health condition; the Spearman's correlation analyses showed selected anthropometric, biochemical, dietary, and SCFA metadata associated with specific bacterial abundances, and although the HPLC did not show relevant differences in SCFA content among the studied groups, FT-ICR MS disclosed the presence of interesting metabolites of complex phenolic, valeric, arachidic, and caprylic acid nature. The major conclusion of our work is that GD, PD, and PE are associated with fecal bacterial microbiota profiles, with distinct predictive metagenomes.

The Association between Gut Microbiome and Pregnancy-Induced Hypertension: A Nested Case–Control Study

(1) Background: Pregnancy-induced hypertension (PIH) is associated with obvious microbiota dysbiosis in the third trimester of pregnancy. However, the mechanisms behind these changes remain unknown. Therefore, this study aimed to explore the relationship between the gut microbiome in early pregnancy and PIH occurrence. (2) Methods: A nested case–control study design was used based on the follow-up cohort. Thirty-five PIH patients and thirty-five matched healthy pregnant women were selected as controls. The gut microbiome profiles were assessed in the first trimester using metagenomic sequencing. (3) Results: Diversity analyses showed that microbiota diversity was altered in early pregnancy. At the species level, eight bacterial species were enriched in healthy controls: Alistipes putredinis, Bacteroides vulgatus, Ruminococcus torques, Oscillibacter unclassified, Akkermansia muciniphila, Clostridium citroniae, Parasutterella excrementihominis and Burkholderiales bacterium_1_1_47. Conversely, Eubacterium rectale, and Ruminococcus bromii were enriched in PIH patients. The results of functional analysis showed that the changes in these different microorganisms may affect the blood pressure of pregnant women by affecting the metabolism of vitamin K₂, sphingolipid, lipid acid and glycine. (4) Conclusion: Microbiota dysbiosis in PIH patients begins in the first trimester of pregnancy, and this may be associated with the occurrence of PIH. Bacterial pathway analyses suggest that the gut microbiome might lead to the development of PIH through the alterations of function modules.

Diversity of the gut, vaginal and oral microbiome among pregnant women in South Africa with and without pre-eclampsia

Background

Changes in microbial communities are a known characteristic of various inflammatory diseases and have been linked to adverse pregnancy outcomes, such as preterm birth. However, there is a paucity of information regarding the taxonomic composition and/or diversity of microbial communities in pre-eclampsia. The aim of this study was to determine the diversity of the gut, vaginal and oral microbiome in a cohort of South African pregnant women with and without pre-eclampsia. The diversity of the gut, vaginal and oral microbiome was determined by targeted next generation sequencing (NGS) of the V3 and V4 region of the 16S rRNA gene on the Illumina MiSeq platform.

Results

In this study population, pre-eclampsia was associated with a significantly higher alpha diversity (P = 0.0472; indicated by the Shannon index) in the vaginal microbiome accompanied with a significant reduction in Lactobacillus spp. (P = 0.0275), compared to normotensive pregnant women. Lactobacillus iners was identified as the predominant species of the vaginal microbiome in both cohorts. High inter-individual variation in alpha diversity was observed in the gut and oral microbiome in both cohorts. Although differences in the relative abundance of bacteria at all phylogenetic levels were observed, overall microbial composition of the gut, oral and vaginal microbiome was not significantly different in the pre-eclampsia cohort compared to the normotensive cohort.

Conclusion

Collectively, a reduction of Lactobacillus spp., and predominance of L. iners in pregnant women with pre-eclampsia could suggest an unstable vaginal microbiome that might predispose pregnant women to develop pre-eclampsia. The lack of significant structural changes in the gut, oral and vaginal microbiome does not suggest that the characterized communities play a role in pre-eclampsia, but could indicate a characteristic unique to the study population. The current study provided novel information on the diversity of the gut, oral and vaginal microbiome among pregnant women in South Africa with and without pre-eclampsia. The current study provides a baseline for further investigations on the potential role of microbial communities in pre-eclampsia.

A Review on Inflammatory Bowel Diseases: Recent Molecular Pathophysiology Advances

Inflammatory bowel diseases are considered immune disorders with a complex genetic architecture involving constantly changing endogenous and exogenous factors. The rapid evolution of genomic technologies and the emergence of newly discovered molecular actors are compelling the research community to reevaluate the knowledge and molecular processes. The human intestinal tract contains intestinal human microbiota consisting of commensal, pathogenic, and symbiotic strains leading to immune responses that can contribute and lead to both systemic and intestinal disorders including IBD. In this review, we attempted to highlight some updates of the new IBD features related to genomics, microbiota, new emerging therapies and some major established IBD risk factors.

Characteristics of the gut microbiota in pregnant women with fetal growth restriction

Background

Fetal growth restriction (FGR) in utero leads to failure of fetus to reach the genetically normal growth potential. Currently available means of treating FGR are limited. And it remains unknown how pregnant women who give birth to FGR fetus differ in gut microbiota composition from normal pregnant women.

Methods

In this case-control study, fecal samples were obtained from maternal rectum in the operation room by an obstetrician under strict aseptic conditions. We compared gut microbiota of 14 pregnant women with FGR and 18 normal controls by performing 16S rDNA amplicon sequencing.

Results

We identified significant differences in β-diversity between the FGR and control groups (P < 0.05). At genus level, Bacteroides, Faecalibacterium and Lachnospira were highly abundant in the FGR subjects, which are significantly enriched in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to glycometabolism.

Conclusion

These findings demonstrated that the distinct composition of the gut microbiota between FGR and normal pregnant women could contribute to an improved understanding of the prevention and treatment of FGR.

Dietary Nutrition and Gut Microbiota Composition in Patients With Hypertensive Disorders of Pregnancy

Objective

The aim is to explore the intakes of dietary nutrients and the changes of gut microbiota composition among patients with hypertensive disorders of pregnancy (HDP) and provide a theoretical basis for the prevention and treatment of HDP.

Methods

This study was conducted at the Maternal and Child Health Care Hospital of Changzhou. A total of 170 pregnant women (72 patients with HDP in the case group and 98 healthy pregnant women in the control group) in the third trimester were enrolled. Dietary nutrient intakes were assessed through a food frequency questionnaire survey. Fresh fecal samples were aseptically collected, and 16S rDNA sequencing was conducted. The intakes of dietary nutrients and the diversity and relative abundance of gut microbiota were compared between pregnant women with and without HDP. A logistic regression model was used to investigate the association between differential gut microbial genera and the risk of HDP.

Results

The daily dietary intakes of vitamin A and vitamin C in pregnant women with HDP were significantly lower than those in the control group. The relative abundances of Bacteroidota, Bacteroidaceae, and Bacteroides were increased, and the relative abundances of Actinobacteriota, Lachnospiraceae, Prevotellaceae, Bifidobacteriaceae, Blautia, Prevotella, and Bifidobacterium were decreased in women with HDP compared with those in the controls. In addition, the relative abundance of Bifidobacterium was positively correlated with dietary intakes of vitamin C and vitamin E in patients with HDP. After adjustment for confounding factors, the odds ratio (95% confidence interval) of HDP for the relative abundance of Bifidobacterium was 0.899 (0.813, 0.995).

Conclusion

The composition of gut microbiota in pregnant women with HDP was significantly changed compared with that of healthy controls. The relative abundance of Bifidobacterium was negatively associated with HDP. Moreover, dietary vitamin C and gut Bifidobacterium may cooperatively contribute to reduce the risk of HDP.

Microbiota medicine: towards clinical revolution

The human gastrointestinal tract is inhabited by the largest microbial community within the human body consisting of trillions of microbes called gut microbiota. The normal flora is the site of many physiological functions such as enhancing the host immunity, participating in the nutrient absorption and protecting the body against pathogenic microorganisms. Numerous investigations showed a bidirectional interplay between gut microbiota and many organs within the human body such as the intestines, the lungs, the brain, and the skin. Large body of evidence demonstrated, more than a decade ago, that the gut microbial alteration is a key factor in the pathogenesis of many local and systemic disorders. In this regard, a deep understanding of the mechanisms involved in the gut microbial symbiosis/dysbiosis is crucial for the clinical and health field. We review the most recent studies on the involvement of gut microbiota in the pathogenesis of many diseases. We also elaborate the different strategies used to manipulate the gut microbiota in the prevention and treatment of disorders. The future of medicine is strongly related to the quality of our microbiota. Targeting microbiota dysbiosis will be a huge challenge.

Gut microbiota in pregnant Malaysian women: a comparison between trimesters, body mass index and gestational diabetes status

Background

The primary purpose of the study is to determine the variation of gut microbiota composition between first (T1) and third trimester (T3); gestational diabetes mellitus (GDM) and non-gestational diabetes mellitus (NGDM); and also within a different category of Body Mass Index (BMI) of selected pregnant Malaysian women.

Methods

A prospective observational study on selected 38 pregnant Malaysian women attending a tertiary medical centre was carried out. Those with preexisting diabetes, metabolic syndrome or any other endocrine disorders were excluded. GDM was determined using oral glucose tolerance test (OGTT) while BMI was stratified as underweight, normal, pre-obese and obese. Fecal samples were then collected during the first trimester (T1) and the third trimester (T3). The V3-V4 region of 16S rRNA gene amplicon libraries were sequenced and analyzed using QIIME (version 1.9.1) and METAGENassist.

Results

Twelve women (31.6%) were diagnosed as GDM. A trend of lower α-diversity indices in GDM, pre-obese and obese pregnant women were observed. Partial Least Squares Discriminant Analysis (PLS-DA) shows a clustering of gut microbiota according to GDM status and BMI, but not by trimester. Genera Acidaminococcus, Clostridium, Megasphaera and Allisonella were higher, and Barnesiella and Blautia were lower in GDM group (P < 0.005). Obese patients had gut microbiota that was enriched with bacteria of Negativicutes and Proteobacteria class such as Megamonas, Succinatimonas and Dialister (P < 0.005). The normal and mild underweight profiles on the other hand had a higher bacteria from the class of Clostridia (Papillibacter, Oscillibacter, Oscillospira, Blautia, Dorea) and Bacteroidia (Alistipes, Prevotella, Paraprevotella) (P < 0.005).

Conclusion

The prevalence and variation of several key bacteria from classes of Negativicutes, Clostridia and Proteobacteria has potential metabolic links with GDM and body weight during pregnancy which require further functional validation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04472-x.

The Diagnostic Potential of Gut Microbiota-Derived Short-Chain Fatty Acids in Preeclampsia

Preeclampsia (PE) is a complex pregnancy-related hypertensive disorder leading to multiorgan dysfunction. It has high maternal, fetal, and neonatal morbidity and mortality rates. The study of gut microbiota and its metabolites in PE deserves further exploration. Thirty-eight pregnant women with PE and 29 healthy pregnant women in the third trimester of their pregnancy were recruited in this study. We used a targeted metabolomics approach to evaluate the short-chain fatty acids (SCFAs) in serum samples. The correlation between SCFAs and clinical characteristics was also explored. The results of mass spectrometry (MS) showed significant differences at the metabolomics level of SCFAs between the PE and healthy control. The metabolic levels of acetate, propionate, isobutyrate, and valerate were significantly increased in the PE group than in the healthy control group. In contrast, caproic acid and butyrate levels were significantly reduced. The correlation analysis showed that urea, systolic, and diastolic blood pressure levels were positively correlated with four types of SCFAs (acetic acid, propionic acid, isobutyric acid, and valeric acid) which increased in the PE group. Furthermore, the neutrophil percentage and the fetal birth weight were negatively correlated with isobutyric acid and valeric acid. In addition, the receiver operating characteristic (ROC) analysis using a generalized linear model showed that multiple SCFAs would be potential diagnostic markers for PE, with high specificity, sensitivity, and area under the curve (AUC). Among them, isobutyric acid (sensitivity: 97.4%, specificity: 100%, AUC = 1.00), propionic acid (sensitivity: 86.8%, specificity: 93.3%, AUC = 0.954) and acetic acid (sensitivity: 86.8%, specificity: 83.3%, AUC = 0.891) depicted significantly higher diagnostic value and potential clinical applications. In summary, the results of this study indicate that SCFAs have the potential to become effective biomarkers for early screening of PE.

Sodium butyrate alleviates pre-eclampsia in pregnant rats by improving the gut microbiota and short-chain fatty acid metabolites production

AIMS

Pre-eclampsia (PE) affects pregnant patients worldwide, but there is no effective treatment for this condition. We aimed to explore the effect of sodium butyrate (NaB) on PE.

METHODS AND RESULTS

In this study, Nω-nitro-L-arginine methyl ester hydrochloride was used to induce PE in pregnant rats. We found that NaB significantly decreased the levels of blood pressure, 24-h protein urine and inflammatory factors (IL-1β, IL-6 and TGF-β), increased the foetal and placental weights and intestinal barrier markers (ZO-1, claudin-5 and occludin) expression. In addition, NaB intervention reduced the levels of soluble fms-like tyrosine kinase 1 and soluble endoglin and increased placental growth factor level. Meanwhile, after NaB treatment, the Treg/Th17 ratio of immune cells in the spleen and small intestine of pregnant rats decreased, while the level of pregnancy-related diamine oxidase increased. Notably, the PE rat treatment with NaB improved gut microbiota compositions, especially for the abundances of Firmicutes and Bacteroides, and significantly increased butyric acid and pentanoic acid levels, which might help to alleviate PE in pregnant rats.

CONCLUSION

In the PE rat model, exogenous NaB improved intestinal barrier function and reduced adverse outcomes, which might be associated with the gut microbiota and its production of SCFA metabolites.

SIGNIFICANCE AND IMPACT OF THE STUDY

NaB might alleviate the adverse outcomes of PE by regulating gut microbiota and its metabolite SCFA, which revealed that NaB might be a potential regulator of gut microbiota and a therapeutic substance for PE.

Maternal microbiome in preeclampsia pathophysiology and implications on offspring health

Preeclampsia is a devastating hypertensive pregnancy disorder that currently affects 2%–8% of pregnancies worldwide. It is associated with maternal and fetal mortality and morbidity and adverse health outcomes both in mom and offspring beyond pregnancy. The pathophysiology is not completely understood, and there are no approved therapies to specifically treat for the disease, with only few therapies approved to manage symptoms. Recent advances suggest that aberrations in the composition of the microbiome may play a role in the pathogenesis of various diseases including preeclampsia. The maternal and uteroplacental environments greatly influence the long‐term health outcomes of the offspring through developmental programming mechanisms. The current review summarizes recent developments on the role of the microbiome in adverse pregnancy outcomes with a focus on preeclampsia. It also discusses the potential role of the maternal microbiome in fetal programming; explores gut‐targeted therapeutics advancement and their implications in the treatment of preeclampsia.

Gut and Reproductive Tract Microbiota Adaptation during Pregnancy: New Insights for Pregnancy-Related Complications and Therapy

Pregnancy is characterized by maternal adaptations that are necessary to create a welcoming and hospitable environment for the fetus. Studies have highlighted how the microbiota modulates several networks in humans through complex molecular interactions and how dysbiosis (defined as quantitative and qualitative alterations of the microbiota communities) is related to human pathologies including gynecological diseases. This review analyzed how maternal uterine, vaginal, and gut microbiomes could impact on fetus health during the gestational period. We evaluated the role of a dysbiotic microbiota in preterm birth, chorioamnionitis, gestational diabetes mellitus and pre-eclampsia. For many years it has been hypothesized that newborns were sterile organisms but in the past few years this paradigm has been questioned through the demonstration of the presence of microbes in the placenta and meconium. In the future, we should go deeper into the concept of in utero colonization to better understand the role of microbiota through the phases of pregnancy. Numerous studies in the literature have already showed interesting results regarding the role of microbiota in pregnancy. This evidence gives us the hope that microbiota modulation could be a novel strategy to reduce the morbidity and mortality related to pregnancy complications in the future.

Gestational gut microbial remodeling is impaired in a rat model of preeclampsia superimposed on chronic hypertension

Preeclampsia is a progressive hypertensive disorder of pregnancy affecting 2%-8% of pregnancies globally. Preexisting chronic hypertension is a major risk factor associated with developing preeclampsia, and growing evidence suggests a role for the gut microbiome in the development of preeclampsia. However, neither alterations in the gut microbiome associated with preeclampsia nor the mechanisms involved are fully understood. In this study, we tested the hypothesis that normal gestational maternal gut microbiome remodeling is impaired in the Dahl salt-sensitive (Dahl S) rat model of superimposed preeclampsia. Gut microbiome profiles of pregnant Dahl S, normal pregnant Sprague-Dawley (SD), and matched virgin controls were assessed by 16S rRNA gene sequencing at baseline; during early, middle, and late pregnancy; and 1-wk postpartum. Dahl S rats had significantly higher abundance in Proteobacteria, and multiple genera were significantly different from SD rats at baseline. The pregnant SD displayed a significant increase in Proteobacteria and genera such as Helicobacter, but these were not different between pregnant and virgin Dahl S rats. By late pregnancy, Dahl S rats had significantly lower α-diversity and Firmicutes compared with their virgin Dahl S controls. β-diversity was significantly different among groups (P < 0.001). KEGG metabolic pathways including those associated with short-chain fatty acids were different in Dahl S pregnancy but not in SD pregnancy. These results reveal an association between chronic hypertension and gut microbiome dysbiosis which may hinder pregnancy-specific remodeling in the gut microbial composition during superimposed preeclampsia.