Association between risk of preeclampsia and maternal plasma trimethylamine-N-oxide in second trimester and at the time of delivery

Plasma trimethylamine N-oxide metabolites in the second trimester predict the risk of hypertensive disorders of pregnancy: a nested case-control study

The relationship between gut microbiota products trimethylamine oxide (TMAO) and related metabolites including betaine, choline and L-carnitine and hypertensive disorders of pregnancy (HDP) is unclear. In order to examine whether plasma TMAO and related metabolites predict the risk of HDP, a nested case-control study was conducted in Chinese women based on a prospective cohort including 9447 participants. 387 pairs of pregnant women (n = 774) were matched and their plasma TMAO, betaine, choline, and L-carnitine at 16-20 gestational weeks were measured by liquid chromatography-mass spectrometry. Odds ratio (OR) and the 95% confidence interval (95% CI) were calculated using the conditional logistic regression, to examine the association between TMAO metabolites and HDP. The findings showed that higher plasma betaine (≥24.94 μmol/L) was associated with a decreased risk of HDP and its subtype gestational hypertension (GH), with adjusted ORs of 0.404 (95% CI: 0.226-0.721) and 0.293 (95% CI: 0.134-0.642), respectively. Higher betaine/choline ratio (>2.64) was associated with a lower risk of HDP and its subtype preeclampsia or chronic hypertension with superimposed preeclampsia (PE/CH-PE), with adjusted ORs of 0.554 (95% CI: 0.354-0.866) and 0.226 (95% CI: 0.080-0.634). Moreover, compared with traditional factors (TFs) model, the TMAO metabolites+ TFs model had a higher predictive ability for PE/CH-PE (all indexes P values < 0.0001). Therefore, it suggests that the detection of plasma betaine and choline in the early second trimester of pregnancy can better assess the risk of HDP.

Gut microbiota-derived trimethylamine N-Oxide: a novel target for the treatment of preeclampsia

Pre-eclampsia (PE) is the most common complication of pregnancy and seriously threatens the health and safety of the mother and child. Studies have shown that an imbalance in gut microbiota can affect the progression of PE. Trimethylamine N-oxide (TMAO) is an intestinal microbiota-derived metabolite that is thought to be involved in the occurrence of PE; however, its causal relationship and mechanism remain unclear. In this clinical cohort study, including 28 patients with eclampsia and 39 matched healthy controls, fecal samples were collected for 16S rRNA gene sequencing, and serum was collected for targeted metabolomics research. The results showed that the level of TMAO and the abundance of its source bacteria had significantly increased in patients with PE, and were positively correlated with the clinical progression of PE. Fecal microbiota transplantation (FMT) was applied to an antibiotic-depleted-treated mouse model and targeted inhibition of TMAO. The results of the FMT experiment revealed that mice that received fecal microbiota transplantation from patients with PE developed typical PE symptoms and increased oxidative stress and inflammatory damage, both of which were reversed by 3,3-Dimethyl-1-butanol (DMB), a TMAO inhibitor, which also improved pregnancy outcomes in the model mice. Similar results were obtained in the classical NG-Nitroarginine methyl ester (L-NAME) induced PE mouse model. Mechanistically, TMAO promotes the progression of PE by regulating inflammatory and oxidative stress-related signaling pathways, affecting the migration and angiogenesis of vascular endothelial cells, as well as the migration and invasion of trophoblast cells. Our results reveal the role and mechanism of gut microbiota and TMAO in the progression of PE, provides new ideas for exploring the pathogenesis and therapeutic targets of PE, and determines the potential application value of TMAO as a target for PE intervention.

ÁP, Alvarez AM. From gut to placenta: understanding how the maternal microbiome models life-long conditions

The microbiome -defined as the microbiota (bacteria, archaea, lower and higher eukaryotes), their genomes, and the surrounding environmental conditions- has a well-described range of physiological functions. Thus, an imbalance of the microbiota composition -dysbiosis- has been associated with pregnancy complications or adverse fetal outcomes. Although there is controversy about the existence or absence of a microbiome in the placenta and fetus during healthy pregnancy, it is known that gut microbiota can produce bioactive metabolites that can enter the maternal circulation and may be actively or passively transferred through the placenta. Furthermore, the evidence suggests that such metabolites have some effect on the fetus. Since the microbiome can influence the epigenome, and modifications of the epigenome could be responsible for fetal programming, it can be experimentally supported that the maternal microbiome and its metabolites could be involved in fetal programming. The developmental origin of health and disease (DOHaD) approach looks to understand how exposure to environmental factors during periods of high plasticity in the early stages of life (e.g., gestational period) influences the program for disease risk in the progeny. Therefore, according to the DOHaD approach, the influence of maternal microbiota in disease development must be explored. Here, we described some of the diseases of adulthood that could be related to alterations in the maternal microbiota. In summary, this review aims to highlight the influence of maternal microbiota on both fetal development and postnatal life, suggesting that dysbiosis on this microbiota could be related to adulthood morbidity.

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.

Changes in the Gut Microbiome and Pathologies in Pregnancy

Pregnancy is a special period in a woman's life when her organism undergoes multiple physiological changes so that the fetus has optimal conditions for growth and development. These include modifications in the composition of the microbiome that occur between the first and third trimesters of pregnancy. There is an increase in Akkermansia, Bifidobacterium, and Firmicutes, which have been associated with an increase in the need for energy storage. The growth in Proteobacteria and Actinobacteria levels has a protective effect on both the mother and the fetus via proinflammatory mechanisms. The aim of the study is to review the research on the relationship between the mother's intestinal microbiome and gestational pathologies. Changes in the maternal gut microbiome is probably one of the mechanisms that occurs in various pregnancy diseases such as preeclampsia, fetal growth restriction, gestational diabetes mellitus, excessive gestational weight gain, and premature birth. For this reason, it seems vital to pay attention to certain interventions that can benefit the affected patients both in the short term, by preventing complications during pregnancy, and in the long term, as one of the mechanisms occurring in various gestational diseases is dysbiosis of the maternal intestinal flora.

Trimethylamine N-Oxide and Its Precursors Are Associated with Gestational Diabetes Mellitus and Pre-Eclampsia in the Boston Birth Cohort

Background

Trimethylamine N-oxide (TMAO) and its precursors choline, betaine, and carnitine have been associated with cardiometabolic disease in nonpregnant adults. However, studies examining TMAO and its precursors in relation to cardiometabolic conditions during pregnancy are lacking.

Objectives

The primary objective was to estimate the association of TMAO and its precursors in maternal and cord plasma with gestational diabetes mellitus (GDM) and pre-eclampsia (PE) among women in the Boston Birth Cohort. A secondary objective was to determine whether associations vary by race/ethnicity.

Methods

ORs for each outcome according to tertiles and to an SD increment of TMAO, choline, betaine, and carnitine were estimated using logistic regression. Final models were adjusted for covariates.

Results

Among 1496 women, 115 women had GDM and 159 had PE during the index pregnancy. Intermetabolite correlations of TMAO and its precursors were stronger within cord plasma (r = 0.38-0.87) than within maternal plasma (r = 0.08-0.62). Maternal TMAO was associated with higher odds of GDM (third compared with first tertile OR: 1.75; 95% CI: 1.04, 2.94), whereas maternal choline, betaine, and carnitine were not associated with GDM. Maternal TMAO and choline were not associated with PE, whereas carnitine was associated with higher (OR: 1.86; 95% CI: 1.18, 2.94) and betaine with lower odds of PE (OR: 0.37; 95% CI: 0.23, 0.59). In cord plasma, TMAO was not associated with GDM or PE, but choline, betaine, and carnitine were associated with higher odds of PE (OR: 3.11; 95% CI: 1.62, 5.96; OR: 2.65; 95% CI: 1.42, 4.93; OR: 2.56; 95% CI: 1.39, 4.69, respectively). Cord choline was associated with lower odds of GDM (OR: 0.52; 95% CI: 0.27, 0.99), whereas other cord metabolites were not significantly associated with GDM. Associations did not vary by race/ethnicity.

Conclusions

TMAO and its precursors were associated with GDM and PE, but the associations differed based on the metabolite medium (maternal compared with cord plasma).This trial was registered at clinicaltrials.gov as NCT03228875.

Gut microbiota-derived metabolite trimethylamine-N-oxide and multiple health outcomes: an umbrella review and updated meta-analysis

BACKGROUND

Trimethylamine-N-oxide (TMAO) is a gut microbiota-derived metabolite produced from dietary nutrients. Many studies have discovered that circulating TMAO concentrations are linked to a wide range of health outcomes.

OBJECTIVES

This study aimed to summarize health outcomes related to circulating TMAO concentrations.

METHODS

We searched the Embase, Medline, Web of Science, and Scopus databases from inception to 15 February, 2022 to identify and update meta-analyses examining the associations between TMAO and multiple health outcomes. For each health outcome, we estimated the summary effect size, 95% prediction CI, between-study heterogeneity, evidence of small-study effects, and evidence of excess-significance bias. These metrics were used to evaluate the evidence credibility of the identified associations.

RESULTS

This umbrella review identified 24 meta-analyses that investigated the association between circulating TMAO concentrations and health outcomes including all-cause mortality, cardiovascular diseases (CVDs), diabetes mellitus (DM), cancer, and renal function. We updated these meta-analyses by including a total of 82 individual studies on 18 unique health outcomes. Among them, 14 associations were nominally significant. After evidence credibility assessment, we found 6 (33%) associations (i.e., all-cause mortality, CVD mortality, major adverse cardiovascular events, hypertension, DM, and glomerular filtration rate) to present highly suggestive evidence.

CONCLUSIONS

TMAO might be a novel biomarker related to human health conditions including all-cause mortality, hypertension, CVD, DM, cancer, and kidney function. Further studies are needed to investigate whether circulating TMAO concentrations could be an intervention target for chronic disease.This review was registered at www.crd.york.ac.uk/prospero/ as CRD42021284730.

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.