The maternal microbiome promotes placental development in mice

Relationships between Gut Microbiota and Autism Spectrum Disorders: Development and Treatment

Many studies have demonstrated the impact of intestinal microbiota on normal brain development. Moreover, the gut microbiota (GM) is impacted by multiple endogenous and environmental factors that may promote gut dysbiosis (GD). An increasing number of studies are investigating the possible role of the GD in the development of neurological and behavioral disorders. For autism spectrum disorders (ASD), specific intestinal bacterial signatures have been identified, knowing that gastrointestinal symptoms are frequently found in ASD. In this review, the peri and post-natal factors modulating the GM are described and the specific gut bacterial signature of ASD children is detailed. Through bidirectional communication between the GM and the brain, several mechanisms are involved in the development of ASD, such as cytokine-mediated neuroinflammation and decreased production of neuroprotective factors such as short-chain fatty acids by the GM. Imbalance of certain neurotransmitters such as serotonin or gamma-aminobutyric acid could also play a role in these gut-brain interactions. Some studies show that this GD in ASD is partly reversible by treatment with pre- and probiotics, or fecal microbiota transplantation with promising results. However, certain limitations have been raised, in particular concerning the short duration of treatment, the small sample sizes and the diversity of protocols. The development of standardized therapeutics acting on GD in large cohort could rescue the gastrointestinal symptoms and behavioral impairments, as well as patient management.

Maternal dysbiosis produces long-lasting behavioral changes in offspring

Advanced maternal age (AMA) is defined as a pregnancy in a woman older than 35 years of age. AMA increases the risk for both maternal and neonatal complications, including miscarriage and stillbirth. AMA has also been linked to neurodevelopmental and neuropsychiatric disorders in the offspring. Recent studies have found that age-associated compositional shifts in the gut microbiota contribute to altered microbial metabolism and enhanced inflammation in the host. We investigated the specific contribution of the maternal microbiome on pregnancy outcomes and offspring behavior by recolonizing young female mice with aged female microbiome prior to pregnancy. We discovered that pre-pregnancy colonization of young dams with microbiome from aged female donors significantly increased fetal loss. There were significant differences in the composition of the gut microbiome in pups born from dams recolonized with aged female biome that persisted through middle age. Offspring born from dams colonized with aged microbiome also had significant changes in levels of neurotransmitters and metabolites in the blood and the brain. Adult offspring from dams colonized with an aged microbiome displayed persistent depressive- and anxiety-like phenotypes. Collectively, these results demonstrate that age-related changes in the composition of the maternal gut microbiome contribute to chronic alterations in the behavior and physiology of offspring. This work highlights the potential of microbiome-targeted approaches, even prior to birth, may reduce the risk of neuropsychiatric disorders.

Calorie restriction during gestation impacts maternal and offspring fecal microbiome in mice

Background

Maternal undernutrition is the most common cause of fetal growth restriction (FGR) worldwide. FGR increases morbidity and mortality during infancy, as well as contributes to adult-onset diseases including obesity and type 2 diabetes. The role of the maternal or offspring microbiome in growth outcomes following FGR is not well understood.

Methods

FGR was induced by 30% maternal calorie restriction (CR) during the second half of gestation in C57BL/6 mice. Pup weights were obtained on day of life 0, 1, and 7 and ages 3, 4 and 16 weeks. Fecal pellets were collected from pregnant dams at gestational day 18.5 and from offspring at ages 3 and 4 weeks of age. Bacterial genomic DNA was used for amplification of the V4 variable region of the 16S rRNA gene. Multivariable associations between maternal CR and taxonomic abundance were assessed using the MaAsLin2 package. Associations between microbial taxa and offspring outcomes were performed using distance-based redundancy analysis and Pearson correlations.

Results

FGR pups weighed about 20% less than controls. Beta but not alpha diversity differed between control and CR dam microbiomes. CR dams had lower relative abundance of Turicibacter, Flexispira, and Rikenella, and increased relative abundance of Parabacteroides and Prevotella. Control and FGR offspring microbiota differed by beta diversity at ages 3 and 4 weeks. At 3 weeks, FGR offspring had decreased relative abundance of Akkermansia and Sutterella and increased relative abundance of Anaerostipes and Paraprevotella. At 4 weeks, FGR animals had decreased relative abundance of Allobaculum, Sutterella, Bifidobacterium, and Lactobacillus, among others, and increased relative abundance of Turcibacter, Dorea, and Roseburia. Maternal Helicobacter abundance was positively associated with offspring weight. Akkermansia abundance at age 3 and 4 weeks was negatively associated with adult weight.

Conclusions

We demonstrate gut microbial dysbiosis in pregnant dams and offspring at two timepoints following maternal calorie restriction. Additional research is needed to test for functional roles of the microbiome in offspring growth outcomes.

The maternal lifestyle in pregnancy: Implications for foetal skeletal muscle development

The world is facing a global nutrition crisis, as evidenced by the rising incidence of metabolic disorders such as obesity, insulin resistance and chronic inflammation. Skeletal muscle is the largest tissue in humans and plays an important role in movement and host metabolism. Muscle fibre formation occurs mainly during the embryonic stage. Therefore, maternal lifestyle, especially nutrition and exercise during pregnancy, has a critical influence on foetal skeletal muscle development and the subsequent metabolic health of the offspring. In this review, the influence of maternal obesity, malnutrition and micronutrient intake on foetal skeletal muscle development is systematically summarized. We also aim to describe how maternal exercise shapes foetal muscle development and metabolic health in the offspring. The role of maternal gut microbiota and its metabolites on foetal muscle development is further discussed, although this field is still in its 'infancy'. This review will provide new insights to reduce the global crisis of metabolic disorders and highlight current gaps to promote further research.

Impact of weight variation on the microbiome of yak dams and calves

Introduction

Limited information exists regarding the microbiome composition of yak calves of varying weights. Therefore, this study aimed to investigate the microbiomes of mother-calf pairs with different weight profiles.

Methods

Fecal and blood samples were collected from both lower-weight (CB) and higher-weight (HB) yak calves, along with their corresponding female yaks (CA, HA).

Results

The results revealed significantly higher levels of T-AOC (total antioxidant capacity) and GSH-Px (glutathione peroxidase) in HB animals (p < 0.001). Sequencing yielded 652,181 and 643,369 filtered reads in female and calf yaks, respectively. Alpha diversity analysis indicated that Chao1, Faith_pd, and Observed species were significantly higher in CA compared to HA (p < 0.01). Furthermore, nine genera were notably different between HA and CA yaks, including Avispirillum, Fimenecus, CAG-1031, Odoribacter 865974, and Jeotgalicoccus A 310962. Compared to CB yaks, CA animals exhibited significant differences in one phylum and six genera, including CAG-485 (p < 0.05), CAG-83 (p < 0.01), Copromorpha (p < 0.01), Phocaeicola A 858004 (p < 0.05), and UBA2253 (p < 0.05).

Conclusion

In summary, higher-weight yak calves demonstrated increased oxidative resistance, and weight profiles were linked to the microbiomes of both female yaks and their calves. These findings offer valuable insights for optimizing yak breeding practices in high-altitude regions.

Gestational Interrelationships among Gut-Metabolism-Transcriptome in Regulating Early Embryo Implantation and Placental Development in Mice

Decidualization of the uterine endometrium is a critical process for embryo implantation in mammals, primarily occurring on gestational day 8 in pregnant mice. However, the interplay between the maternal gut microbiome, metabolism, and the uterus at this specific time point remains poorly understood. This study employed a multi-omics approach to investigate the metabolic, gut microbiome, and transcriptomic changes associated with early pregnancy (gestational day 8 (E8)) in mice. Serum metabolomics revealed a distinct metabolic profile at E8 compared to controls, with the differential metabolites primarily enriched in amino acid metabolism pathways. The gut microbial composition showed that E8 mice exhibited higher alpha-diversity and a significant shift in beta-diversity. Specifically, the E8 group displayed a decrease in pathogenic Proteobacteria and an increase in beneficial Bacteroidetes and S24-7 taxa. Transcriptomics identified myriads of distinct genes between the E8 and control mice. The differentially expressed genes were enriched in pathways involved in alanine, aspartate, and glutamate metabolism, PI3K-Akt signaling, and the PPAR signaling pathway. Integrative analysis of the multi-omics data uncovered potential mechanistic relationships among the differential metabolites, gut microbiota, and uterine gene expression changes. Notably, the gene Asns showed strong correlations with specific gut S24-7 and metabolite L-Aspartatic acid, suggesting its potential role in mediating the crosstalk between the maternal environment and embryo development during early pregnancy. These findings provide valuable insights into the complex interplay between the maternal metabolome, the gut microbiome, and the uterine transcriptome in the context of early pregnancy, which may contribute to our understanding of the underlying mechanisms of embryo implantation and development.

Prenatal environmental risk factors for autism spectrum disorder and their potential mechanisms

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that is globally increasing in prevalence. The rise of ASD can be partially attributed to diagnostic expansion and advocacy efforts; however, the interplay between genetic predisposition and modern environmental exposures is likely driving a true increase in incidence. A range of evidence indicates that prenatal exposures are critical. Infection during pregnancy, gestational diabetes, and maternal obesity are established risk factors for ASD. Emerging areas of research include the effects of maternal use of selective serotonin reuptake inhibitors, antibiotics, and exposure to toxicants during pregnancy on brain development and subsequent ASD. The underlying pathways of these risk factors remain uncertain, with varying levels of evidence implicating immune dysregulation, mitochondrial dysfunction, oxidative stress, gut microbiome alterations, and hormonal disruptions. This narrative review assesses the evidence of contributing prenatal environmental factors for ASD and associated mechanisms as potential targets for novel prevention strategies.

In utero human intestine contains maternally derived bacterial metabolites

Understanding when host-microbiome interactions are first established is crucial for comprehending normal development and identifying disease prevention strategies. Furthermore, bacterially derived metabolites play critical roles in shaping the intestinal immune system. Recent studies have demonstrated that memory T cells infiltrate human intestinal tissue early in the second trimester, suggesting that intestinal immune education begins in utero. Our previous study reported a unique fetal intestinal metabolomic profile with an abundance of several bacterially derived metabolites and aryl hydrocarbon receptor (AHR) ligands implicated in mucosal immune regulation. To follow up on this work, in the current study, we demonstrate that a number of microbial byproducts present in fetal intestines in utero are maternally derived and vertically transmitted to the fetus. Notably, these bacterially derived metabolites, particularly short chain fatty acids and secondary bile acids, are likely biologically active and functional in regulating the fetal immune system and preparing the gastrointestinal tract for postnatal microbial encounters, as the transcripts for their various receptors and carrier proteins are present in second trimester intestinal tissue through single-cell transcriptomic data.

Host-microbe interactions: communication in the microbiota-gut-brain axis

Animals harbor a diverse array of symbiotic micro-organisms that coexist in communities across different body sites. These microbes maintain host homeostasis and respond to environmental insults to impact host physiological processes. Trillions of indigenous microbes reside in the gastrointestinal tract and engage with the host central nervous system (microbiota-gut-brain axis) by modulating immune responses, interacting with gut intrinsic and extrinsic nervous system, and regulating neuromodulators and biochemicals. These gut microbiota to brain signaling pathways are constantly informed by each other and are hypothesized to mediate brain health across the lifespan. In this review, we will examine the crosstalk of gut microbiota to brain communications in neurological pathologies, with an emphasis on microbial metabolites and neuromodulators, and provide a discussion of recent advances that help elucidate the microbiota as a therapeutic target for treating brain and behavioral disorders.

Obesity and diet independently affect maternal immunity, maternal gut microbiota and pregnancy outcome in mice

Introduction

Maternal obesity poses risks for both mother and offspring during pregnancy, with underlying mechanisms remaining largely unexplored. Obesity is associated with microbial gut dysbiosis and low-grade inflammation, and also the diet has a major impact on these parameters. This study aimed to investigate how maternal obesity and diet contribute to changes in immune responses, exploring potential associations with gut microbiota dysbiosis and adverse pregnancy outcomes in mice.

Methods

Before mating, C57BL/6 mice were assigned to either a high-fat-diet (HFD) or low-fat-diet (LFD) to obtain obese (n=17) and lean (n=10) mice. To distinguish between the effects of obesity and diet, 7 obese mice were switched from the HFD to the LFD from day 7 until day 18 of pregnancy ("switch group"), which was the endpoint of the study. T helper (Th) cell subsets were studied in the spleen, mesenteric lymph nodes (MLN) and Peyer's patches (PP), while monocyte subsets and activation status were determined in maternal blood (flow cytometry). Feces were collected before and during pregnancy (day 7,14,18) for microbiota analysis (16S rRNA sequencing). Pregnancy outcome included determination of fetal and placental weight.

Results

Obesity increased splenic Th1 and regulatory T cells, MLN Th1 and PP Th17 cells and enhanced IFN-γ and IL-17A production by splenic Th cells upon ex vivo stimulation. Switching diet decreased splenic and PP Th2 cells and classical monocytes, increased intermediate monocytes and activation of intermediate/nonclassical monocytes. Obesity and diet independently induced changes in the gut microbiota. Various bacterial genera were increased or decreased by obesity or the diet switch. These changes correlated with the immunological changes. Fetal weight was lower in the obese than the lean group, while placental weight was lower in the switch than the obese group.

Discussion

This study demonstrates that obesity and diet independently impact peripheral and intestinal immune responses at the end of pregnancy. Simultaneously, both factors affect specific bacterial gut genera and lead to reduced fetal or placental weight. Our data suggest that switching diet during pregnancy to improve maternal health is not advisable and it supports pre/probiotic treatment of maternal obesity-induced gut dysbiosis to improve maternal immune responses and pregnancy outcome.

The relationship between the gut microbiota and thyroid disorders

Disorders of the thyroid gland are common, more prevalent in women than in men, and range from inflammatory to neoplastic lesions. Autoimmune thyroid diseases (AITD) affect 2-5% of the population, while thyroid cancer is the most frequent endocrine malignancy. Treatment for AITD is still restricted to management rather than prevention or cure. Progress has been made in identifying genetic variants that predispose to AITD and thyroid cancer, but the increasing prevalence of all thyroid disorders indicates that factors other than genes are involved. The gut microbiota, which begins to develop before birth, is highly sensitive to diet and the environment, providing a potential mechanism for non-communicable diseases to become communicable. Its functions extend beyond maintenance of gut integrity: the gut microbiota regulates the immune system, contributes to thyroid hormone metabolism and can generate or catabolize carcinogens, all of which are relevant to AITD and thyroid cancer. Observational and interventional studies in animal models support a role for the gut microbiota in AITD, which has been confirmed in some reports from human cohorts, although considerable geographic variation is apparent. Reports of a role for the microbiota in thyroid cancer are more limited, but evidence supports a relationship between gut dysbiosis and thyroid cancer.

Interactions between host and gut microbiota in gestational diabetes mellitus and their impacts on offspring

Gestational diabetes mellitus (GDM) is characterized by insulin resistance and low-grade inflammation, and most studies have demonstrated gut dysbiosis in GDM pregnancies. Overall, they were manifested as a reduction in microbiome diversity and richness, depleted short chain fatty acid (SCFA)-producing genera and a dominant of Gram-negative pathogens releasing lipopolysaccharide (LPS). The SCFAs functioned as energy substance or signaling molecules to interact with host locally and beyond the gut. LPS contributed to pathophysiology of diseases through activating Toll-like receptor 4 (TLR4) and involved in inflammatory responses. The gut microbiome dysbiosis was not only closely related with GDM, it was also vital to fetal health through vertical transmission. In this review, we summarized gut microbiota signature in GDM pregnancies of each trimester, and presented a brief introduction of microbiome derived SCFAs. We then discussed mechanisms of microbiome-host interactions in the physiopathology of GDM and associated metabolic disorders. Finally, we compared offspring microbiota composition from GDM with that from normal pregnancies, and described the possible mechanism.

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.

Early life microbiome influences on development of the mucosal innate immune system

The gut microbiota is well known to possess immunomodulatory capacities, influencing a multitude of cellular signalling pathways to maintain host homeostasis. Although the formation of the immune system initiates before birth in a sterile environment, an emerging body of literature indicates that the neonatal immune system is influenced by a first wave of external stimuli that includes signals from the maternal microbiota. A second wave of stimulus begins after birth and must be tightly regulated during the neonatal period when colonization of the host occurs concomitantly with the maturation of the immune system, requiring a fine adjustment between establishing tolerance towards the commensal microbiota and preserving inflammatory responses against pathogenic invaders. Besides integrating cues from commensal microbes, the neonatal immune system must also regulate responses triggered by other environmental signals, such as dietary antigens, which become more complex with the introduction of solid food during the weaning period. This "window of opportunity" in early life is thought to be crucial for the proper development of the immune system, setting the tone of subsequent immune responses in adulthood and modulating the risk of developing chronic and metabolic inflammatory diseases. Here we review the importance of host-microbiota interactions for the development and maturation of the immune system, particularly in the early-life period, highlighting the known mechanisms involved in such communication. This discussion is focused on recent data demonstrating microbiota-mediated education of innate immune cells and its role in the development of lymphoid tissues.

Expression and clinical significance of short-chain fatty acids in patients with intrahepatic cholestasis of pregnancy

BACKGROUND

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver condition that typically arises in the middle and late stages of pregnancy. Short-chain fatty acids (SCFAs), prominent metabolites of the gut microbiota, have significant connections with various pregnancy complications, and some SCFAs hold potential for treating such complications. However, the metabolic profile of SCFAs in patients with ICP remains unclear.

AIM

To investigate the metabolic profiles and differences in SCFAs present in the maternal and cord blood of patients with ICP and determine the clinical significance of these findings.

METHODS

Maternal serum and cord blood samples were collected from both patients with ICP (ICP group) and normal pregnant women (NP group). Targeted metabolomics was used to assess the SCFA levels in these samples.

RESULTS

Significant differences in maternal SCFAs were observed between the ICP and NP groups. Most SCFAs exhibited a consistent declining trend in cord blood samples from the ICP group, mirroring the pattern seen in maternal serum. Correlation analysis revealed a positive correlation between maternal serum SCFAs and cord blood SCFAs [r (Pearson) = 0.88, P = 7.93e-95]. In both maternal serum and cord blood, acetic and caproic acids were identified as key metabolites contributing to the differences in SCFAs between the two groups (variable importance for the projection > 1). Receiver operating characteristic analysis demonstrated that multiple SCFAs in maternal blood have excellent diagnostic capabilities for ICP, with caproic acid exhibiting the highest diagnostic efficacy (area under the curve = 0.97).

CONCLUSION

Compared with the NP group, significant alterations were observed in the SCFAs of maternal serum and cord blood in the ICP group, although they displayed distinct patterns of change. Furthermore, the SCFA levels in maternal serum and cord blood were significantly positively correlated. Notably, certain maternal serum SCFAs, specifically caproic and acetic acids, demonstrated excellent diagnostic efficiency for ICP.

Nutrition during pregnancy: Influence on the gut microbiome and fetal development

Pregnancy is a finely tuned process, with the health and well-being of the developing fetus determined by the metabolic status and dietary intake of the mother. The maternal gut microbiome is remodeled during pregnancy, and this, coupled with the maternal nutrient intake during gestation shapes the production of metabolites that can cross the placenta and affect fetal development. As posited by the Developmental Origins of Health and Disease Hypothesis, such environmental influences can have major effects on the developing organ systems. When occurring at particularly sensitive gestational time points, these developmental programming events can have long lasting effects on offspring adaptation to the postnatal environment, and major health implications later in life. This review will summarize current knowledge on how pregnancy and maternal dietary intake intrinsically and extrinsically modify maternal gut microbiota composition and metabolite production. Further, we will assess how these factors shape the fetal landscape and ultimately contribute to offspring health. DOHaD, fetal development, metabolites, microbiome, nutrition, pregnancy, short-chain fatty acids.

Shaping Microbiota During the First 1000 Days of Life

Given that the host-microbe interaction is shaped by the immune system response, it is important to understand the key immune system-microbiota relationship during the period from conception to the first years of life. The present work summarizes the available evidence concerning human reproductive microbiota, and also, the microbial colonization during early life, focusing on the potential impact on infant development and health outcomes. Furthermore, we conclude that some dietary strategies including specific probiotics and other-biotics could become potentially valuable tools to modulate the maternal-neonatal microbiota during this early critical window of opportunity for targeted health outcomes throughout the entire lifespan.

Microbiota during pregnancy and early life: role in maternal-neonatal outcomes based on human evidence

Here, we explored the vast potential of microbiome-based interventions in preventing and managing non-communicable diseases including obesity, diabetes, allergies, celiac disease, inflammatory bowel diseases, malnutrition, and cardiovascular diseases across different life stages. We discuss the intricate relationship between microbiome and non-communicable diseases, emphasizing on the "window of opportunity" for microbe-host interactions during the first years after birth. Specific biotics and also live biotherapeutics including fecal microbiota transplantation emerge as pivotal tools for precision medicine, acknowledging the "one size doesn't' fit all" aspect. Challenges in implementation underscore the need for advanced technologies, scientific transparency, and public engagement. Future perspectives advocate for understanding maternal-neonatal microbiome, exploring the maternal exposome and delving into human milk's role in the establishment and restoration of the infant microbiome and its influence over health and disease. An integrated scientific approach, employing multi-omics and accounting for inter-individual variance in microbiome composition and function appears central to unleash the full potential of early-life microbiome interventions in revolutionizing healthcare.