Neonatal sepsis leads to early rise of rare serum bile acid tauro-omega-muricholic acid (TOMCA)

Exploring the Vital Role of Microbiota Metabolites in Early-Life Health

Early-life gut microbiota metabolites profoundly influence gut homeostasis, neurodevelopment, metabolic regulation, and immune system maturation. However, there is still a lack of comprehensive summaries and discussions regarding gut microbiota metabolites during early-life stages. This review systematically analyzes microbiota metabolites, including short-chain fatty acids, secondary bile acids, tryptophan metabolites, and branched-chain fatty acids, and delves into their production mechanisms and temporal dynamics. Additionally, the review highlights how maternal factors, breastfeeding, complementary feeding, and environmental influences shape the composition and metabolic functions of the early-life gut microbiota, emphasizing that early life is a crucial window for lifelong health interventions. By integrating the latest research findings and identifying knowledge gaps, this review emphasizes the molecular mechanisms of gut microbiota metabolites and their role in addressing common early-life diseases, including their potential as early biomarkers for screening, prevention, improvement, and even treatment of early diseases, as well as predicting their potential related diseases. On the basis of these insights, this review lays the foundation for future research and practical applications, aiming to promote optimal health from infancy to childhood.

Elevated total bile acid levels as an independent predictor of mortality in pediatric sepsis

BACKGROUND

The close relationship between bile acid (BA) metabolism and sepsis has been investigated in recent years, as knowledge of the role of the gut microbiome and metabolomics in sepsis has grown and become more comprehensive.

METHODS

Patients with sepsis who were admitted to the PICU of the Children's Hospital, Zhejiang University School of Medicine from January 2016 to December 2021 were enrolled in this study. Preoperative non-infectious pediatric patients undergoing elective surgeries in our hospital's department of surgery were recruited as controls during the same period. Clinical data were collected and analyzed.

RESULTS

702 children were enrolled, comprising 538 sepsis survivors, 164 sepsis fatalities, and 269 non-infected controls. Statistical analysis revealed that total BA (TBA) increased in both the early and severe stages of pediatric sepsis. In the severe stage, TBA (OR = 2.898, 95% CI 1.946-4.315, p < 0.05) was identified as a risk factor for sepsis. A clinical model identified TBA (the cut-off value is >17.95 µmol/L) as an independent predictor of sepsis mortality with an AUC of 0.842 (95% CI 0.800-0.883), sensitivity of 54.9%, specificity of 96.6%, and HR = 7.658 (95% CI 5.575-10.520).

CONCLUSIONS

The study showed that elevated TBA was associated with a heightened risk of mortality in pediatric sepsis.

IMPACT

Many clinical indicators show differences between children with sepsis and the control group, among which the difference in serum total bile acid levels is the most significant. During the hospitalization of the patients, the overall bile acid levels in the sepsis death group were higher and exhibited greater fluctuations compared to the survival group, with significant differences. Serum total bile acid levels can serve as effective biomarker for predicting the prognosis of children with sepsis.

High-Throughput Combined Analysis of Saliva Microbiota and Metabolomic Profile in Chinese Periodontitis Patients: A Pilot Study

The onset and progression of periodontitis involves complicated interactions between the dysbiotic oral microbiota and disrupted host immune-inflammatory response, which can be mirrored by the changes in salivary metabolites profile. This pilot study sought to examine the saliva microbiome and metabolome in the Chinese population by the combined approach of 16s rRNA sequencing and high-throughput targeted metabolomics to discover potential cues for host-microbe metabolic interactions. Unstimulated whole saliva samples were collected from eighteen Stage III and IV periodontitis patients and thirteen healthy subjects. Full-mouth periodontal parameters were recorded. The taxonomic composition of microbiota was obtained by 16s rRNA sequencing, and the metabolites were identified and measured by ultra-high performance liquid chromatography and mass spectrometry-based metabolomic analysis. The oral microbiota composition displayed marked changes where the abundance of 93 microbial taxa differed significantly between the periodontitis and healthy group. Targeted metabolomics identified 103 differential metabolites between the patients and healthy individuals. Functional enrichment analysis demonstrated the upregulation of protein digestion and absorption, histidine metabolism, and nicotinate and nicotinamide metabolism pathways in the dysbiotic microbiota, while the ferroptosis, tryptophan metabolism, glutathione metabolism, and carbon metabolism pathways were upregulated in the patients. Correlation analysis confirmed positive relationships between the clinical parameters, pathogen abundances, and disease-related metabolite levels. The integral analysis of the saliva microbiome and metabolome yielded an accurate presentation of the dysbiotic oral microbiome and functional alterations in host-microbe metabolism. The microbial and metabolic profiling of the saliva could be a potential tool in the diagnosis, prognosis evaluation, and pathogenesis study of periodontitis.

Bile acid metabolism and signaling: Emerging pharmacological targets of dietary polyphenols

Beyond their role as emulsifiers of lipophilic compounds, bile acids (BAs) are signaling endocrine molecules that show differential affinity and specificity for a variety of canonical and non-canonical BA receptors. Primary BAs (PBAs) are synthesized in the liver while secondary BAs (SBAs) are gut microbial metabolites of PBA species. PBAs and SBAs signal to BA receptors that regulate downstream pathways of inflammation and energy metabolism. Dysregulation of BA metabolism or signaling has emerged as a feature of chronic disease. Dietary polyphenols are non-nutritive plant-derived compounds associated with decreased risk of metabolic syndrome, type-2 diabetes, hepatobiliary and cardiovascular disease. Evidence suggests that the health promoting effects of dietary polyphenols are linked to their ability to alter the gut microbial community, the BA pool, and BA signaling. In this review we provide an overview of BA metabolism and summarize studies that link the cardiometabolic improvements of dietary polyphenols to their modulation of BA metabolism and signaling pathways, and the gut microbiota. Finally, we discuss approaches and challenges in deciphering cause-effect relationships between dietary polyphenols, BAs, and gut microbes.

Bile Acids, Intestinal Barrier Dysfunction, and Related Diseases

The intestinal barrier is a precisely regulated semi-permeable physiological structure that absorbs nutrients and protects the internal environment from infiltration of pathological molecules and microorganisms. Bile acids are small molecules synthesized from cholesterol in the liver, secreted into the duodenum, and transformed to secondary or tertiary bile acids by the gut microbiota. Bile acids interact with bile acid receptors (BARs) or gut microbiota, which plays a key role in maintaining the homeostasis of the intestinal barrier. In this review, we summarize and discuss the recent studies on bile acid disorder associated with intestinal barrier dysfunction and related diseases. We focus on the roles of bile acids, BARs, and gut microbiota in triggering intestinal barrier dysfunction. Insights for the future prevention and treatment of intestinal barrier dysfunction and related diseases are provided.

Identification of biomarkers and the mechanisms of multiple trauma complicated with sepsis using metabolomics

Sepsis after trauma increases the risk of mortality rate for patients in intensive care unit (ICUs). Currently, it is difficult to predict outcomes in individual patients with sepsis due to the complexity of causative pathogens and the lack of specific treatment. This study aimed to identify metabolomic biomarkers in patients with multiple trauma and those with multiple trauma accompanied with sepsis. Therefore, the metabolic profiles of healthy persons designated as normal controls (NC), multiple trauma patients (MT), and multiple trauma complicated with sepsis (MTS) (30 cases in each group) were analyzed with ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS)-based untargeted plasma metabolomics using collected plasma samples. The differential metabolites were enriched in amino acid metabolism, lipid metabolism, glycometabolism and nucleotide metabolism. Then, nine potential biomarkers, namely, acrylic acid, 5-amino-3-oxohexanoate, 3b-hydroxy-5-cholenoic acid, cytidine, succinic acid semialdehyde, PE [P-18:1(9Z)/16:1(9Z)], sphinganine, uracil, and uridine, were found to be correlated with clinical variables and validated using receiver operating characteristic (ROC) curves. Finally, the three potential biomarkers succinic acid semialdehyde, uracil and uridine were validated and can be applied in the clinical diagnosis of multiple traumas complicated with sepsis.

The Covert Surge: Murine Bile Acid Levels Are Associated With Pruritus in Pediatric Autoimmune Sclerosing Cholangitis

OBJECTIVES

The exact etiology of pruritus in chronic cholestasis is unknown. Pruritus intensity does not correlate with common biochemical indices and there is a lack of biomarkers guiding diagnosis and treatment. We explored profiles of bile acids (BA) and muricholic acids (MCA) as well as autotaxin (ATX) antigen levels as potential circulating biomarkers of pruritus in pediatric patients.

METHODS

In 27 pediatric cholestatic patients [autoimmune sclerosing cholangitis (ASC) n = 20 (with pruritus n = 6, without pruritus n = 14); progressive familial intrahepatic cholestasis (PFIC) n = 7 (with pruritus n = 5, without pruritus n = 2)] and 23 age-matched controls pruritus was assessed by a visual analog scale of pruritus (PVAS). We obtained profiles of serum human BA including MCA using a mass-spectrometry assay and ATX antigen levels with a commercial ELISA.

RESULTS

PFIC and ASC patients exhibited significantly higher BA-, and MCA levels, than healthy controls, but only PFIC patients showed elevated ATX antigen levels higher [median: 1,650 ng/ml, interquartile rang (IQR): 776.9-3,742] compared to controls (median: 315.9 ng/ml, IQR: 251.1-417.2; PFIC p = 0.0003). ASC patients with pruritus showed only a minor increase in total BA (tBA) levels (median: 76.5 μmol/L, IQR: 54.7-205), but strikingly higher T-conjugated BA (median: 16.4 μmol/L, IQR: 8.9-41.4) and total MCA (tMCA) (median: 1.15 μmol/L, IQR: 0.77-2.44) levels compared to ASC patients without pruritus (tBA median: 24.3 μmol/L, IQR: 16.2-80.8; p < 0.0408; T-conjugated BA median: 1.3 μmol/L, IQR: 0.8-4.9; p = 0.0023; tMCA median: 0.30 μmol/L, IQR: 0.13-0.64, p = 0.0033). BA/MCA profiles distinctly differed depending on presence/absence of pruritus. Different from PFIC patients, ATX antigen levels were not significantly elevated in ASC patients with (median: 665.8 ng/ml, IQR: 357.8-1,203) and without pruritus (median: 391.0 ng/ml, IQR: 283.2-485.6). In ASC patients, tBA, tMCA, and ATX antigen levels did not correlate with pruritus severity.

CONCLUSION

Despite the same underlying disease, pediatric ASC patients with pruritus exhibit significantly altered BA profiles and MCA levels compared to ASC patients without pruritus. ATX antigen levels seem to have little diagnostic or prognostic meaning in ASC patients. An increased ATX activity alone seems not to be causal for pruritus genesis in ASC patients.

CLINICAL TRIAL REGISTRATION

[www.drks.de], identifier [DRKS00026913].

Bile acids as regulatory molecules and potential targets in metabolic diseases

Bile acids are important hydroxylated steroids that are synthesized in the liver from cholesterol for intestinal absorption of lipids and other fatty-nutrient. They also display remarkable and immense functions such as regulating immune responses, managing the apoptosis of cells, participating in glucose metabolism, and so on. Some bile acids were used for the treatment or prevention of diseases such as gallstones, primary biliary cirrhosis, and colorectal cancer. Meanwhile, the accumulation of toxic bile acids leads to apoptosis, necrosis, and inflammation. Alteration of bile acids metabolism, as well as the gut microbiota that interacted with bile acids, contributes to the pathogenesis of metabolic diseases. Therefore, the purpose of this review is to summarize the current functions and pre-clinical or clinical applications of bile acids, and to further discuss the alteration of bile acids in metabolic disorders as well as the manipulation of bile acids metabolism as potential therapeutic targets.

Metabolic characteristics of plasma bile acids in patients with intrahepatic cholestasis of pregnancy-mass spectrometric study

INTRODUCTION

Intrahepatic cholestasis of pregnancy (ICP) is one of the more common complications in the middle and late stages of pregnancy, which requires early detection and intervention.

OBJECTIVE

The aim of the study is to investigate the changes in the metabolic profile of bile acids (BAs) in plasma of pregnant women with ICP and to look biomarkers for the diagnosis and grading of ICP, and to explore the disease mechanism.

METHODS

The targeted metabolomics based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to analyze plasma BAs.

RESULTS

Twenty-seven BAs can be quantified in all participants. Among them, 22 BAs were identified as differential BAs between ICP and control groups. Five BAs include 3β-CA, 3β-DCA, CDCA-3Gln, NCA, and Tβ-MCA, were found to be associated with ICP for the first time. Nine BAs include NCA, GCA, GCDCA, GHCA, GUDCA, HCA, TCA, TCDCA and THCA, can be used as possible ICP diagnostic biomarkers. Four BAs, i.e., GLCA, THCA, GHCA and TLCA-3S may be used as potential biomarkers for ICP grading.

CONCLUSION

There were significant differences in plasma BA profiles between ICP patients and the control. The BA profiles of mild ICP group and severe ICP group partially overlapped. Potential diagnostic and grading BA markers were identified. A significant characteristic of ICP group was the increase of conjugated BAs. A mechanism to sustain the equilibrium of BA metabolism and adaptive response has been developed in ICP patients to accelerate excretion and detoxification.

TGR5 signaling mitigates parenteral nutrition-associated liver disease

Bile acid receptors regulate the metabolic and immune functions of circulating enterohepatic bile acids. This process is disrupted by administration of parenteral nutrition (PN), which may induce progressive hepatic injury for unclear reasons, especially in the newborn, leading to PN-associated liver disease. To explore the role of bile acid signaling on neonatal hepatic function, we initially observed that Takeda G protein receptor 5 (TGR5)-specific bile acids were negatively correlated with worsening clinical disease markers in the plasma of human newborns with prolonged PN exposure. To test our resulting hypothesis that TGR5 regulates critical liver functions to PN exposure, we used TGR5 receptor deficient mice (TGR5^-/-). We observed PN significantly increased liver weight, cholestasis, and serum hepatic stress enzymes in TGR5^-/- mice compared with controls. Mechanistically, PN reduced bile acid synthesis genes in TGR5^-/-. Serum bile acid composition revealed that PN increased unconjugated primary bile acids and secondary bile acids in TGR5^-/- mice, while increasing conjugated primary bile acid levels in TGR5-competent mice. Simultaneously, PN elevated hepatic IL-6 expression and infiltrating macrophages in TGR5^-/- mice. However, the gut microbiota of TGR5^-/- mice compared with WT mice following PN administration displayed highly elevated levels of Bacteroides and Parabacteroides, and possibly responsible for the elevated levels of secondary bile acids in TGR5^-/- animals. Intestinal bile acid transporters expression was unchanged. Collectively, this suggests TGR5 signaling specifically regulates fundamental aspects of liver bile acid homeostasis during exposure to PN. Loss of TGR5 is associated with biochemical evidence of cholestasis in both humans and mice on PN.NEW & NOTEWORTHY Parenteral nutrition is associated with deleterious metabolic outcomes in patients with prolonged exposure. Here, we demonstrate that accelerated cholestasis and parental nutrition-associated liver disease (PNALD) may be associated with deficiency of Takeda G protein receptor 5 (TGR5) signaling. The microbiome is responsible for production of secondary bile acids that signal through TGR5. Therefore, collectively, these data support the hypothesis that a lack of established microbiome in early life or under prolonged parenteral nutrition may underpin disease development and PNALD.

Ratio of Conjugated Chenodeoxycholic to Muricholic Acids is Associated with Severity of Nonalcoholic Steatohepatitis

OBJECTIVE

Bile acids (BAs) are important molecules in the progression of nonalcoholic fatty liver disease. This study aimed to investigate BA profile alterations in Chinese nonalcoholic steatohepatitis (NASH) patients.

METHODS

BA profiles in serum and liver tissues were determined by ultraperformance liquid chromatography coupled to tandem mass spectrometry in patients from two different clinical centers.

RESULTS

A total of 134 participants were enrolled in this study to serve as the training (n = 87) and validation (n = 47) cohorts. The ratio of circulating conjugated chenodeoxycholic acids to muricholic acids (P = 0.001) was elevated from healthy controls to non-NASH individuals to NASH individuals in a stepwise manner in the training cohort and was positively associated with the histological severity of NASH: steatosis (R2  = 0.12), lobular inflammation (R2  = 0.12), ballooning (R2  = 0.11), and fibrosis stage (R2  = 0.18). The ratio was elevated in the validation cohort of NASH patients (P < 0.001), and it was able to predict NASH (area under the receiver operating characteristic curve: 75%) and significant fibrosis (area under the receiver operating characteristic curve: 71%) in these two cohorts. Moreover, this elevated ratio and impaired farnesoid X receptor signaling were found in the NASH liver.

CONCLUSIONS

Altered BA profile in NASH is closely associated with the severity of liver lesions, and it has the potential for predicting NASH development.