Maternal Amino Acid Status in Severe Preeclampsia: A Cross-Sectional Study

From methionine to sulfide: Exploring the diagnostic and therapeutic potential of sulfur-containing biomolecules in hypertension

Sulfur-containing amino acids are involved in the regulation of vascular activity and blood pressure. Clinically, a positive correlation was found between serum homocysteine levels and blood pressure. On the other hand, methionine and cysteine levels were reduced in hypertensive patients. Recently, the redox state of sulfur-containing amino acids has emerged as potential diagnostic marker of cardiovascular health. Metabolomic studies have revealed a shift in thiol/disulfide ratio toward oxidized forms and overproduction of thiyl radicals in hypertensive patients. Although accumulating evidence confirms that sulfur-containing amino acids are essential for the maintaining of redox homeostasis and blood pressure control, their hypotensive and antioxidant properties have been primarily demonstrated in animal studies. While several groups are developing new targeted and triggered sulfur-based donors, standardized pharmacological interventions for hypertensive patients are largely absent and pose a challenge for future research. In this review, we summarize recent studies that investigate the role of sulfur-containing amino acids and their redox-active metabolites, including glutathione and sulfide, in blood pressure control and the development of systemic hypertension.

Maternal-offspring brain and tissue cross-talk in preeclampsia: insights from a rat model

This study aimed to investigate the differential metabolic profiles across maternal and offspring brains, serum, and placental tissues in preeclampsia (PE), with a particular focus on elucidating the maternal-offspring brain and tissue cross-talk that may contribute to the complex pathophysiology of PE. PE was induced in rats using the nitric oxide synthase inhibitor N-nitro-L-arginine methyl ester (L-NAME) to simulate both early-onset PE (EOPE) and late-onset PE (LOPE). We utilized non-targeted proton nuclear magnetic resonance (NMR) metabolomics to characterize the metabolic profiles of serum, placental tissue extracts, and brain tissues from both mothers and offspring. Multivariate analysis, Spearman correlation, Density-Based Spatial Clustering of Applications with Noise algorithm, Data-Driven Statistical Predictive Correlation network analysis and Tissue heterogeneity analysis were employed to explore tissue-specific metabolic signatures and their interactions. Following L-NAME induction, both EOPE and LOPE presented significant metabolic differences and shared traits across tissues, with distinct tissue-specific responses characterizing the metabolic profile of PE. Serum from both PE groups showed a decrease in tryptophan, isobutyrate, and lactate, with an increase in betaine. Lactate was upregulated in placental tissues, highlighting its metabolic role. Extensive intra-tissue metabolic correlations and inter-tissue metabolite exchanges were detected among the maternal brain, serum, placenta, and offspring brain across all three experimental groups. EOPE and LOPE exhibited distinctly different metabolic characteristics and trajectories of differential metabolites, along with diverse interaction patterns between the maternal/offspring brain and the placenta. This study uncovers the multi-tissue metabolic remodeling in response to preeclampsia, implying that addressing pathophysiological stress is crucial and may have potential implications for neurological outcomes. The comprehensive analysis highlights the pivotal role of the brain-placenta axis in preeclampsia, advocating for a classified diagnostic and management approach.

Nutrigenetic Investigations in Preeclampsia

Background: Preeclampsia is a leading cause of pregnancy-related maternal and fetal morbidity and mortality. Although its precise cause and prevention remain unclear, risk factors such as overweight and inadequate nutrient intake (e.g., calcium, folic acid, and vitamin D) are known to increase its incidence. Recent research has focused on the genetic predisposition to preeclampsia, identifying polymorphisms that may affect enzyme or receptor function. This study aims to review existing literature examining the relationship between genetic polymorphisms, BMI (body mass index), and nutrient levels in preeclampsia to develop more actionable therapeutic strategies. Methods: A systematic review was conducted to analyze studies on the nutrigenetic relationship between BMI, micronutrients, and preeclampsia. Results: A total of 17 studies investigating 12 genes related to BMI and 10 studies exploring 3 genes in relation to micronutrient levels were included in the analysis. Several polymorphisms associated with preeclampsia were found to be influenced by maternal BMI or serum vitamin levels. The interactions between certain gene variants and these factors suggest that both BMI and micronutrient status may modify the risk of developing preeclampsia in genetically predisposed individuals. Conclusions: Our findings emphasize the potential for reanalyzing existing data by categorizing based on genotype and nutrient levels. This approach could yield more personalized dietary and therapeutic recommendations for managing preeclampsia. In the future, genetic information may support the development of tailored nutritional counseling during pregnancy to mitigate preeclampsia risk.

Exploring altered free amino acids and metabolites: Insights into the metabolic landscape of preeclampsia

INTRODUCTION

Preeclampsia (PE) is a complex disease that poses a risk for maternal and perinatal morbidity and mortality. This study aimed to investigate the role of maternal serum amino acids (AAs) levels in PE.

MATERIALS AND METHODS

A total of 56 pregnant women (26 with PE and 30 controls) were included in the study. The participants had a confirmed gestational age between 24 and 37 weeks. The mean body mass index (BMI) for the PE group was 33.1 kg/m2, while the control group had a mean BMI of 29.6 kg/m2. AAs levels were quantified, and statistical analyses were performed to identify significant differences between the two groups. Receiver Operating Characteristic (ROC) curve analysis was employed the diagnostic potential of specific AAs.

RESULTS

We observed significantly elevated levels of multiple AAs in the PE group, including citrulline, lysine, ethanolamine, ornithine and histidine. Citrulline exhibited exceptional predictive power for PE with 100.0% sensitivity and specificity at a cutoff of 7.79 µmol/L, reflected in an area under the curve (AUC) of 1.000.

DISCUSSION

Our study highlights the crucial involvement of altered amino acid levels, specifically in the urea cycle, disruptions in lysine and ethanolamine metabolism in PE development. Exploring these changes may reveal new therapeutic targets, providing insights into the disease's molecular mechanisms. Understanding amino acid metabolism in PE not only informs therapeutic strategies but also holds the potential to revolutionize early diagnosis and intervention.

Investigating genetic links between blood metabolites and preeclampsia

BACKGROUND

Observational studies have revealed that metabolic disorders are closely related to the development of preeclampsia (PE). However, there is still a research gap on the causal role of metabolites in promoting or preventing PE. We aimed to systematically explore the causal association between circulating metabolites and PE.

METHODS

Single nucleotide polymorphisms (SNPs) from genome-wide association study (GWAS) of 486 blood metabolites (7,824 participants) were extracted as instrumental variables (P < 1 × 10- 5), GWAS summary statistics for PE were obtained from FinnGen consortium (7,212 cases and 194,266 controls) as outcome, and a two-sample Mendelian randomization (MR) analysis was conducted. Inverse variance weighted (IVW) was set as the primary method, with MR-Egger and weighted median as auxiliary methods; the instrumental variable strength and confounding factors were also assessed. Sensitivity analyses including MR-Egger, Cochran's Q test, MR-PRESSO and leave-one-out analysis were performed to test the robustness of the MR results. For significant associations, repeated MR and meta-analysis were performed by another metabolite GWAS (8,299 participants). Furthermore, significantly associated metabolites were subjected to a metabolic pathway analysis.

RESULTS

The instrumental variables for the metabolites ranged from 3 to 493. Primary analysis revealed a total of 12 known (e.g., phenol sulfate, citrulline, lactate and gamma-glutamylglutamine) and 11 unknown metabolites were associated with PE. Heterogeneity and pleiotropy tests verified the robustness of the MR results. Validation with another metabolite GWAS dataset revealed consistency trends in 6 of the known metabolites with preliminary analysis, particularly the finding that genetic susceptibility to low levels of arachidonate (20:4n6) and citrulline were risk factors for PE. The pathway analysis revealed glycolysis/gluconeogenesis and arginine biosynthesis involved in the pathogenesis of PE.

CONCLUSIONS

This study identifies a causal relationship between some circulating metabolites and PE. Our study presented new perspectives on the pathogenesis of PE by integrating metabolomics with genomics, which opens up avenues for more accurate understanding and management of the disease, providing new potential candidate metabolic molecular markers for the prevention, diagnosis and treatment of PE. Considering the limitations of MR studies, further research is needed to confirm the causality and underlying mechanisms of these findings.

Predicting the onset of preeclampsia by longitudinal monitoring of metabolic changes throughout pregnancy with Raman spectroscopy

Preeclampsia is a life-threatening pregnancy disorder. Current clinical assays cannot predict the onset of preeclampsia until the late 2nd trimester, which often leads to poor maternal and neonatal outcomes. Here we show that Raman spectroscopy combined with machine learning in pregnant patient plasma enables rapid, highly sensitive maternal metabolome screening that predicts preeclampsia as early as the 1st trimester with >82% accuracy. We identified 12, 15 and 17 statistically significant metabolites in the 1st, 2nd and 3rd trimesters, respectively. Metabolic pathway analysis shows multiple pathways corresponding to amino acids, fatty acids, retinol, and sugars are enriched in the preeclamptic cohort relative to a healthy pregnancy. Leveraging Pearson's correlation analysis, we show for the first time with Raman Spectroscopy that metabolites are associated with several clinical factors, including patients' body mass index, gestational age at delivery, history of preeclampsia, and severity of preeclampsia. We also show that protein quantification alone of proinflammatory cytokines and clinically relevant angiogenic markers are inadequate in identifying at-risk patients. Our findings demonstrate that Raman spectroscopy is a powerful tool that may complement current clinical assays in early diagnosis and in the prognosis of the severity of preeclampsia to ultimately enable comprehensive prenatal care for all patients.

Maternal serum amino acid levels as predictors of premature rupture of membranes: A comprehensive analysis

INTRODUCTION

The aim of this study is to investigate the association between altered maternal serum amino acids (AAs) levels and premature rupture of membranes (pPROM) in pregnant women.

METHODS

We conducted a case-control study involving 60 pregnant women diagnosed with pPROM and 60 healthy pregnant women as controls. Amino acid levels were quantified using high-performance liquid chromatography. Receiver operating characteristic (ROC) curve analysis was performed to determine the predictive capability of specific AAs for pPROM.

RESULTS

Our findings revealed that lysine, glycine, and glutamic acid levels were significantly elevated in the pPROM group compared with the control group. Lysine, with a threshold value exceeding 137.90 μmol/L, exhibited the highest predictive accuracy, with an area under the curve (AUC) of 0.796 (p < 0.001), sensitivity of 66.7 %, and specificity of 80.0 %. Glycine, with a cut-off value of >242.48 μmol/L, had an AUC of 0.789 (p < 0.001), sensitivity of 83.3 %, and specificity of 65.0 %. Glutamic acid, at a threshold of 111.40 μmol/L, demonstrated an AUC of 0.787 (p < 0.001), sensitivity of 88.3 %, and specificity of 65.0 %. These AAs could effectively predict the occurrence of pPROM.

CONCLUSION

Elevated blood levels of lysine, glycine, and glutamic acid were found to be associated with pPROM. These AAs serve as potential predictive biomarkers for pPROM, with lysine showing the highest AUC and sensitivity. Identifying such biomarkers may contribute to the development of non-invasive diagnostic tools for pPROM risk assessment, enabling timely interventions and improved maternal and fetal outcomes.

One-carbon metabolism-related nutrients intake is associated with lower risk of preeclampsia in pregnant women: a matched case-control study

Many studies have suggested that folate plays a role in preeclampsia (PE) risks, but few studies have assessed folate-related 1-carbon metabolism (OCM)-related nutrients with the risk of PE. We hypothesized that OCM-related nutrients are associated with PE. A 1:1 matched case-control study was conducted to explore the association between dietary OCM-related nutrients intake and the risk of PE in pregnant Chinese women. Four hundred and forty pairs of pregnant women with PE and hospital-based, healthy pregnant women, matched according to gestational week (±1 week) and age (±3 years), were recruited. Dietary intake was assessed using a validated 78-item semiquantitative food frequency questionnaire. Multivariate conditional logistic regression was used to estimate odds ratios (ORs) and 95% CIs. Restricted cubic splines were plotted to evaluate the dose-response relationship between dietary OCM-related nutrient intake and the risk of PE. Intake of folate, vitamin B₆, vitamin B₁₂, methionine, and total choline were inversely related to the risk of PE after adjustment for covariates (all P trend < .05). Adjusted ORs (95% CIs) for quartile 4 versus quartile 1 were 0.71 (0.55-0.93) for folate, 0.66 (0.50-0.87) for vitamin B₆, 0.68 (0.52-0.88) for vitamin B₁₂, 0.77 (0.60-0.81) for methionine, and 0.67 (0.51-0.87) for total choline. This study suggests that dietary OCM-related nutrients intake is associated with lower odds of PE in pregnant Chinese women.