Protective effect of oral histidine on hypertension in Dahl salt-sensitive rats induced by high-salt diet

Elevated isoleucine may be a protective factor for primary hypertension: A pooled causal effect study

Hypertension continues to pose a huge burden to global public health. Abnormal metabolism not only serves as a risk factor for hypertension but also acts as a driving force in its aggravation. However, there remains a lack of large-scale causal demonstration based on extensive samples. Our study aims to investigate the causal relationship between metabolism and primary hypertension (PH) using Mendelian randomization analysis. We used genome-wide association studies instrumental variables for Mendelian randomization association analysis integrating the diagnosis results of PH in 3 populations from East Asia, the Middle East, and Africa with serum metabolites and metabolite ratios. This allowed us to identify predictive metabolites and metabolic pathways for diagnosing or treating PH. Inverse-variance weighting was the main model for establishing causal associations. In addition horizontal pleiotropy test, linkage disequilibrium test, and sensitivity analysis were employed to test the explanatory power of instrumental variables. A total of 10,922 cases of PH and 8299 cases of metabolomics detection cohorts were included in the study. In East Asian, Middle Eastern, and African populations, we found 36, 57, and 40 known metabolites respectively strongly associated with PH (P < .05). Cross-section and meta-analysis of these strongly correlated metabolites across the 3 ethnic groups revealed 7 common metabolites. Notably, elevated isoleucine (odds ratio = 0.74, 95% confidence interval: 0.56-0.96) was demonstrated as a potential protective factor against PH across 3 ethnic groups. The metabolites associated with PH have certain polymorphisms in different populations. Isoleucine may be a promising biomarker for PH diagnosis or treatment, but more clinical validation is needed.

Revealing the links between hair metal(loids) and alterations in blood pressure among children in e-waste recycling areas through urinary metabolomics

Hypertension is prevalent in e-waste recycling areas, and elevated blood pressure in children significantly increases the risk of hypertension in adulthood. However, the associations and toxic pathways between chronic exposure to metal(loids) and elevated blood pressure are rarely investigated. In this study, we measured the levels of 29 hair metal(loids) (chronic exposure biomarkers) and blood pressure in 667 susceptible children from an e-waste recycling area to explore their relationships. Paired urine metabolomics analysis was also performed to interpret potential mechanistic pathways. Results showed that the hypertension prevalence in our recruited children (13.0 %) exceeded the average rate (9.5 %) for Chinese children aged 6-17 years. The top five abundant metal(loids), including lead, strontium, barium, and zinc, demonstrated the most profound associations with elevated systolic blood pressure. Quantile g-computation, weighted quantile sum, and Bayesian kernel machine regression analysis jointly demonstrated a significant association between chronic exposure to metal(loids) mixture and systolic blood pressure. Interestingly, selenium showed significant antagonistic interactions with these four metals, suggesting that supplementing selenium may help children resist the elevated blood pressure induced by metal(loids) exposure. Increased metal(loids) and blood pressure levels were significantly linked to changes in urine metabolomics. Structural equation model indicated that androsterone glucuronide and N-Acetyl-1-aspartylglutamic acid were the significant mediators of the associations between metal(loids) and blood pressure, with mediation effects of 77.4 % and 29.0 %, respectively, suggesting that androsterone glucuronide and N-Acetyl-1-aspartylglutamic acid may be involved in the development of metal-induced blood pressure elevating effect. Girls were more vulnerable to metal(loids)-induced hormonal imbalance, especially androsterone glucuronide, than boys. Chronic exposure to metal(loids) at e-waste recycling sites may contribute to elevated blood pressure in children through disrupting various metabolism pathways, particularly hormonal balance. Our study provides new insights into potential mechanistic pathways of metal(loids)-induced changes in children's blood pressure.

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.

Targeted metabolomic analysis of serum amino acids in heart failure patients

Heart failure (HF) has been recognized as a global epidemic with high rates of morbidity, hospitalization, and mortality. The role of amino acids, which provide the body with energy, in the development of HF is still unclear. The aim of this study was to explore changes in serum amino acids in patients with HF and identify potential biomarkers. First, the serum amino acid metabolism profiles of 44 patients with HF and 30 healthy controls (Con) were quantitatively measured. Then, candidate markers were identified through the utilization of T test, multivariate statistical analysis, and receiver operating characteristic (ROC) curve analysis. The results found that there were 11 amino acid levels that were significantly different between patients with HF and Con. Based on ROC curve analysis, the biomarkers of eight amino acids (Glutamic acid, Taurine, L-aspartic acid, L-ornithine, Ethanolamine, L-Serine, L-Sarcosine, and Cysteine) showed high sensitivity and specificity (AUC > 0.90), and binary logistic regression analysis was used in MetaboAnalyst 5.0. Among the amino acids examined, six exhibited notable alterations in accordance with the severity of HF. In conclusion, this study cannot only provide clinicians with an objective diagnostic approach for the early identification of HF, but also enhances comprehension of the underlying mechanisms involved in the pathogenesis of HF.

Study on the mechanism of Coptis chinensis Franch. And its main active components in treating Alzheimer's disease based on SCFAs using Orbitrap Fusion Lumos Tribrid MS

ETHNOPHARMACOLOGICAL RELEVANCE

Coptis chinensis Franch. (CCF), as an extensively used traditional Chinese medicine, has therapeutic effects on Alzheimer's disease (AD), but its mechanism of action has not yet been elucidated.

AIM OF THE STUDY

This study aims to reveal the mechanism of action of CCF via the gut-brain axis, and provide a new strategy for the clinical treatment of AD.

MATERIALS AND METHODS

APPswe/PS1ΔE9 mice were used as AD models, and were given CCF extract by intragastric administration. Barnes maze was used to test the therapeutic effect of CCF on the treatment of AD. To reveal the mechanism of action of CCF in the treatment of AD, Vanquish Flex UHPLC-orbitrap fusion lumos mass was chosen to detect endogenous differential metabolite; MetaboAnalyst 5.0 was applied to derive relevant metabolic pathways; similarly, to explore the effects of CCF on the gut-brain axis, Vanquish Flex UPLC-Orbitrap fusion lumos mass was utilized to detect the changes in the content of SCFAs in AD mice after CCF administration; the prototype components and metabolites in CCF were identified by UPLC/ESI/qTOF-MS, then their effects on Bifidobacterium breve were explored.

RESULTS

CCF shortened the latency time of AD mice, improved the target quadrant ratio of AD mice, and made the maze roadmap simpler of AD mice; CCF regulated fifteen potential metabolites of AD mice, interestingly, ILA (indole-3-lactic acid) in SCFAs (short-chain fatty acids) was also included; CCF acted on histidine and phenylalanine metabolic pathways of AD mice; CCF increased the contents of acetic acid and ILA in AD mice; magnoflorine, jatrorrhizine, coptisine, groenlandicine, thalifendine, palmatine, berberine, epiberberine, hydroxylated jatrorrhizine, and 3-methoxydemethyleneberberine in CCF were detected in fecal samples of AD mice; magnoflorine, palmatrubine, 13-methylberberine, berberine, coptisine, and palmatine promoted the growth of Bifidobacterium breve.

CONCLUSIONS

we have demonstrated that CCF acts on the gut-brain axis by regulating SCFAs to treat AD.

Renal histaminergic system and acute effects of histamine receptor 2 blockade on renal damage in the Dahl salt-sensitive rat

Histamine is involved in the regulation of immune response, vasodilation, neurotransmission, and gastric acid secretion. Although elevated histamine levels and increased expression of histamine metabolizing enzymes have been reported in renal disease, there is a gap in knowledge regarding the mechanisms of histamine-related pathways in the kidney. We report here that all four histamine receptors as well as enzymes responsible for the metabolism of histamine are expressed in human and rat kidney tissues. In this study, we hypothesized that the histaminergic system plays a role in salt-induced kidney damage in the Dahl salt-sensitive (DSS) rat, a model characterized with inflammation-driven renal lesions. To induce renal damage related to salt sensitivity, DSS rats were challenged with 21 days of a high-salt diet (4% NaCl); normal-salt diet (0.4% NaCl)-fed rats were used as a control. We observed lower histamine decarboxylase and higher histamine N-methyltransferase levels in high-salt diet-fed rats, indicative of a shift in histaminergic tone; metabolomics showed higher histamine and histidine levels in the kidneys of high-salt diet-fed rats, whereas plasma levels for both compounds were lower. Acute systemic inhibition of histamine receptor 2 in the DSS rat revealed that it lowered vasopressin receptor 2 in the kidney. In summary, we established here the existence of the local histaminergic system, revealed a shift in the renal histamine balance during salt-induced kidney damage, and provided evidence that blockage of histamine receptor 2 in the DSS rat affects water balance and urine concentrating mechanisms.NEW & NOTEWORTHY Histamine is a nitrogenous compound crucial for the inflammatory response. The knowledge regarding the renal effects of histamine is very limited. We showed that renal epithelia exhibit expression of the components of the histaminergic system. Furthermore, we revealed that there was a shift in the histaminergic tone in salt-sensitive rats when they were challenged with a high-salt diet. These data support the notion that histamine plays a role in renal epithelial physiological and pathophysiological functions.

Sex Differences in Fatty Acid Metabolism and Blood Pressure Response to Dietary Salt in Humans

Salt sensitivity is a trait in which high dietary sodium (Na+) intake causes an increase in blood pressure (BP). We previously demonstrated that in the gut, elevated dietary Na+ causes dysbiosis. The mechanistic interplay between excess dietary Na+-induced alteration in the gut microbiome and sex differences is less understood. The goal of this study was to identify novel metabolites in sex differences and blood pressure in response to a high dietary Na+ intake. We performed stool and plasma metabolomics analysis and measured the BP of human volunteers with salt intake above or below the American Heart Association recommendations. We also performed RNA sequencing on human monocytes treated with high salt in vitro. The relationship between BP and dietary Na+ intake was different in women and men. Network analysis revealed that fatty acids as top subnetworks differentially changed with salt intake. We found that women with high dietary Na+ intake have high levels of arachidonic acid related metabolism, suggesting a role in sex differences of the blood pressure response to Na+. The exposure of monocytes to high salt in vitro upregulates the transcription of fatty acid receptors and arachidonic acid-related genes. These findings provide potentially novel insights into metabolic changes underlying gut dysbiosis and inflammation in salt sensitivity of BP.

Metabolomics reveals the defense mechanism of histidine supplementation on high-salt exposure-induced hepatic oxidative stress

AIMS

This study mainly evaluated the protective mechanism of histidine against the hepatic oxidative stress after high-salt exposure (HSE) through combined analysis of non-targeted metabolomics and biological metabolic networks.

MATERIALS AND METHODS

Dahl salt-sensitive (SS) rats were fed with normal-salt diet or HSE ± histidine in addition to drinking water for 14 days. Gas chromatography-mass spectrometry was used to analyze the hepatic metabolites. The metabolic profile was analyzed by SIMCA-14.1, the metabolic correlation network was performed using Gephi-0.9.2, and pathway enrichment was analyzed using MetaboAnalyst 5.0 online website.

KEY FINDINGS

Results indicated that HSE disturbed the hepatic metabolic profile, generated abnormal liver metabolism and exacerbated oxidative stress. Histidine supplementation significantly reversed the hepatic metabolic profile. Of note, 14 differential metabolic pathways were enriched after histidine supplementation, most of which played an important role in ameliorating redox and nitric oxide (NO) metabolism. Histidine administration decreased the levels of hydroperoxide and malondialdehyde, and increased the activities of antioxidant enzymes (Catalase, Superoxide Dismutase, Glutathione S-transferase and Glutathione reductases). Histidine effectively enhanced the endogenous synthesis of glutathione by increasing the levels of glutamate and cysteine, thereby enhancing the antioxidant capacity of the glutathione system. After histidine administration, lysine, glutamate, and hypotaurine owned a higher metabolic centrality in the correlation network. In addition, histidine could also effectively increase the endogenous synthesis of NO by enhancing the _L-arginine/NO pathway.

SIGNIFICANCE

This study offers new insights into the metabolic mechanisms underlying the antioxidant protective effect of histidine on the liver.

Comparison of the Chemical Components, Efficacy and Mechanisms of Action of Chrysanthemum morifolium Flower and Its Wild Relative Chrysanthemum indicum Flower against Liver-Fire Hyperactivity Syndrome of Hypertension via Integrative Analyses

To clarify the differences in the clinical application scope of Chrysanthemum morifolium flower (CMF) and Chrysanthemum indicum flower (CIF), two herbs of similar origin, an integrated strategy of network pharmacology, molecular pharmacology, and metabolomics was employed, with a view to investigating the commonalities and dissimilarities in chemical components, efficacy and mechanisms of action. Initial HPLC-Q-TOF-MS analysis revealed that CMF and CIF had different flavonoid constituents. The biological processes underlying the therapeutic effects of CMF and CIF on liver-fire hyperactivity syndrome of hypertension (LFHSH) were predicted to be related to inflammatory response, fatty acid production, and other pathways based on network pharmacology analysis. ELISA, molecular docking, Western blot, and metabolomics techniques showed similar effects of CMF and CIF in lowering blood pressure, resistance to tissue, organ and functional damage, and dyslipidemia. However, distinct effects were found in the regulation of inflammatory response, PI3K-Akt and NF-κB signaling pathways, lipid anabolism, renin-angiotensin system, and metabolic abnormalities. The comparable efficacies of CMF and CIF, despite having distinct mechanisms of action, may be attributed to the integration and counteraction of their different regulating capabilities on the above anti-LFHSH mechanisms. This study offers a vital platform for assessment of differential and precise applications of herbs of close origin with similar but slightly different medicinal properties, and provides a research strategy for bridging Chinese medicine and modern precision medicine.

Momordica charantia Extract Confers Protection Against Hypertension in Dahl Salt-Sensitive Rats

Hypertension is one of the main factors of cardiovascular disease worldwide and is strongly related to the overall mortality. High salt intake is a major risk factors for hypertension. Identifying functional foods that can help prevent mechanistic abnormalities mediating salt-induced hypertension is an issue of considerable nutraceutical and scientific interest. Dietary Momordica charantia may be an alternative approach to avoid salt-induced hypertension. Dahl salt-sensitive (DSS) rats were used to determine whether Momordica charantia water extracts (ME) exerts anti-hypertensive effects in the present study. ME gavage could significantly prevented the increase of blood pressure, blood urea nitrogen, creatinine, and urine protein-to-creatinine ratio of DSS rats. Metabolomics analysis indicated that high-salt diet induced abnormal amino acid metabolism was related to nitric oxide (NO) deficiency, but ME gavage could upregulate the activities of nitric oxide synthase, aspartate aminotransferase, argininosuccinate lyase, argininosuccinate synthase and restore endogenous synthesis of arginine and NO. Meanwhile, renal function was improved after ME gavage. Citrulline, as one of the important component in ME, could attenuate salt-induced hypertension by increasing endogenous synthesis of arginine and NO. Antioxidants in ME, such as phenolic compound, may avoid high-salt induced oxidative stress in DSS rats, which may be another mechanism by which ME prevented blood pressure increase. Thus, the present study indicated that feeding Momordica charantia could avoid high-salt-induced hypertension in DSS rats.

1H NMR serum metabolomics and its endogenous network pharmacological analysis of gushudan on kidney-yang-deficiency-syndrome rats

The pharmacodynamics, ¹H NMR metabolomics and endogenous network pharmacology strategy approaches were integrated to investigate the preventive mechanism of Gushudan (GSD) on kidney-yang-deficiency-syndrome (KYDS) rats in this study. Firstly, the KYDS rat model was achieved by hydrocortisone induction, and the efficacy of GSD on KYDS model rats was assessed by the pharmacodynamic indicators. Next, the comprehensive untargeted serum metabolic profile of rats was obtained in ¹H NMR metabolomics study, 29 potential biomarkers closely associated with KYDS were identified, which were mainly involved in carbohydrate metabolism, amino acid metabolism and intestinal flora metabolism. In addition, the potential biomarkers-targets-pathways-disease metabolic network was further investigated for deeper understanding the preventive effects of GSD on KYDS rats and its mechanism, which was further obtained for the important targets related to biomarkers and diseases such as NOS3, PTGS2 and CXCL8, and important metabolic pathways such as glyoxylate and dicarboxylate metabolism, arginine and proline metabolism, and microbial metabolism in diverse environments. Finally, compared with our previous anti-osteoporosis study of GSD, it suggested that some similar metabolic pathways, which would provide some scientific reference of the existence of the kidney-bone axis under the traditional Chinese medicine (TCM) theory of "kidney dominates bone".

Nuciferine attenuates acute ischemic stroke in a rat model: a metabolomic approach for the mechanistic study

Nuciferine is a promise therapeutic candidate for ischemic stroke. 1H NMR metabolomics was conducted in this study to further elucidate its pharmacological mechanism, which is helpful to be used as a potential treatment for stroke clinically.

Pseudolaric Acid B Attenuates High Salt Intake-Induced Hypertensive Left Ventricular Remodeling by Modulating Monocyte/Macrophage Phenotypes

Background

Studies in ApoE knockout mice have shown that pseudolaric acid B (PB) can act as an immunomodulatory drug and attenuate atherosclerosis progression by modulating monocyte/macrophage phenotypes. Our previous study demonstrated that high salt intake could shift the phenotype of monocytes/macrophages to an inflammatory phenotype, and that this shift was related to hypertension and hypertensive left ventricular (LV) remodeling. However, no comprehensive assessment of the effects of PB on hypertensive LV remodeling has been conducted.

Material/Methods

In this study, RAW264.7 macrophages cultured with different concentrations of NaCl were used to investigate the modulating effects of PB on macrophage phenotype. Furthermore, N-nitro-l-arginine methyl ester hypertensive mice were used to investigate the modulating effects of PB on monocyte phenotype. LV remodeling was investigated by echocardiography. LV morphologic staining (for cardiomyocyte hypertrophy and collagen deposition) was performed at the time of sacrifice.

Results

The results showed that PB significantly improved the viability of RAW264.7 cells, suppressed their phagocytic and migration abilities, and inhibited their phenotypic shift to M1 macrophages. In addition, the blood pressure of PB-treated mice was significantly decreased relative to that of control mice. Furthermore, after PB treatment, the percentage of Ly6C^hi monocytes was significantly decreased while that of Ly6C^lo monocytes was apparently increased. Moreover, PB preserved LV function and alleviated myocardial fibrosis and cardiomyocyte hypertrophy as measured at the end of the experimental period. The transfer of monocytes from PB-treated mice to hypertensive mice achieved the same effects.

Conclusions

Together, these findings indicate that PB exerts its protective effects on hypertensive LV remodeling by modulating monocyte/macrophage phenotypes and warrants further investigation.

Plasma Imidazole Propionate Is Positively Correlated with Blood Pressure in Overweight and Obese Humans

Background: The gut microbiota and its metabolites are essential for host health and dysbiosis has been involved in several pathologic conditions such as type 2 diabetes (T2D) and cardiovascular disease (CVD). Recent studies have identified that plasma imidazole propionate (ImP), a microbial-produced metabolite, is increased in patients with prediabetes and T2D. More recently, ImP was found to be significantly increased in patients with overt CVD. Here, we aimed to investigate the association between ImP and CVD risk factors: blood pressure, HDL-cholesterol, LDL-cholesterol and insulin-resistance in overweight and obese subjects without T2D or use of any metabolic diseases-related medication. Methods: Plasma metabolites, including ImP, were determined in 107 male or post-menopausal women with overweight/obesity, but without T2D. Insulin-sensitivity was assessed with the gold standard method: the hyperinsulinemic-euglycemic clamp using the isotope [6,6-²H₂] glucose and expressed as glucose rate of disposal (Rd) for peripheral insulin sensitivity and suppression of endogenous glucose production (EGP) for hepatic insulin sensitivity. Results: Partial correlation analysis controlled for BMI and age showed a significant correlation between ImP and diastolic blood pressure (r_s = 0.285, p = 0.004) and a borderline significance with systolic blood pressure (r_s = 0.187, p = 0.060); however, systolic and diastolic blood pressure did not correlate with ImP precursor histidine (r_s = 0.063, p = 0.526 and r = −0.038, p = 0.712, respectively). We did not find a correlation between ImP with LDL-cholesterol or HDL-cholesterol (r_s = −0.181, p = 0.064 and r_s = 0.060, p = 0.546, respectively). Furthermore, there was no association between plasma ImP concentrations and Rd and EGP suppression. Conclusion: In this cohort with overweight/obese subjects without T2D, plasma ImP concentrations were positively correlated with diastolic blood pressure but not with insulin-sensitivity.