Bile acid metabolism is altered in those with insulin resistance after gestational diabetes mellitus

Relationship between gut microbiota and the pathogenesis of gestational diabetes mellitus: a systematic review

Introduction

Gestational diabetes mellitus (GDM) is a form of gestational diabetes mellitus characterized by insulin resistance and abnormal function of pancreatic beta cells. In recent years, genomic association studies have revealed risk and susceptibility genes associated with genetic susceptibility to GDM. However, genetic predisposition cannot explain the rising global incidence of GDM, which may be related to the increased influence of environmental factors, especially the gut microbiome. Studies have shown that gut microbiota is closely related to the occurrence and development of GDM. This paper reviews the relationship between gut microbiota and the pathological mechanism of GDM, in order to better understand the role of gut microbiota in GDM, and to provide a theoretical basis for clinical application of gut microbiota in the treatment of related diseases.

Methods

The current research results on the interaction between GDM and gut microbiota were collected and analyzed through literature review. Keywords such as "GDM", "gut microbiota" and "insulin resistance" were used for literature search, and the methodology, findings and potential impact on the pathophysiology of GDM were systematically evaluated.

Results

It was found that the composition and diversity of gut microbiota were significantly associated with the occurrence and development of GDM. Specifically, the abundance of certain gut bacteria is associated with an increased risk of GDM, while other changes in the microbiome may be associated with improved insulin sensitivity. In addition, alterations in the gut microbiota may affect blood glucose control through a variety of mechanisms, including the production of short-chain fatty acids, activation of inflammatory pathways, and metabolism of the B vitamin group.

Discussion

The results of this paper highlight the importance of gut microbiota in the pathogenesis of GDM. The regulation of the gut microbiota may provide new directions for the treatment of GDM, including improving insulin sensitivity and blood sugar control through the use of probiotics and prebiotics. However, more research is needed to confirm the generality and exact mechanisms of these findings and to explore potential clinical applications of the gut microbiota in the management of gestational diabetes. In addition, future studies should consider the interaction between environmental and genetic factors and how together they affect the risk of GDM.

Ji-Ni-De-Xie ameliorates type 2 diabetes mellitus by modulating the bile acids metabolism and FXR/FGF15 signaling pathway

Introduction: Ji-Ni-De-Xie (JNDX) is a traditional herbal preparation in China. It is widely used to treat type 2 diabetes mellitus (T2DM) in traditional Tibetan medicine system. However, its antidiabetic mechanisms have not been elucidated. The aim of this study is to elucidate the underlying mechanism of JNDX on bile acids (BAs) metabolism and FXR/FGF15 signaling pathway in T2DM rats. Methods: High-performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-QQQ-MS) and UPLC-Q-Exactive Orbitrap MS technology were used to identify the constituents in JNDX. High-fat diet (HFD) combined with streptozotocin (45 mg∙kg-1) (STZ) was used to establish a T2DM rat model, and the levels of fasting blood-glucose (FBG), glycosylated serum protein (GSP), homeostasis model assessment of insulin resistance (HOMA-IR), LPS, TNF-α, IL-1β, IL-6, TG, TC, LDL-C, HDL-C, and insulin sensitivity index (ISI) were measured to evaluate the anti-diabetic activity of JNDX. In addition, metagenomic analysis was performed to detect changes in gut microbiota. The metabolic profile of BAs was analyzed by HPLC-QQQ-MS. Moreover, the protein and mRNA expressions of FXR and FGF15 in the colon and the protein expressions of FGF15 and CYP7A1 in the liver of T2DM rats were measured by western blot and RT-qPCR. Results: A total of 12 constituents were identified by HPLC-QQQ-MS in JNDX. Furthermore, 45 chemical components in serum were identified from JNDX via UPLC-Q-Exactive Orbitrap MS technology, including 22 prototype components and 23 metabolites. Using a T2DM rat model, we found that JNDX (0.083, 0.165 and 0.33 g/kg) reduced the levels of FBG, GSP, HOMA-IR, LPS, TNF-α, IL-1β, IL-6, TG, TC, and LDL-C, and increased ISI and HDL-C levels in T2DM rats. Metagenomic results demonstrated that JNDX treatment effectively improved gut microbiota dysbiosis, including altering some bacteria (e.g., Streptococcus and Bacteroides) associated with BAs metabolism. Additionally, JNDX improved BAs disorder in T2DM rats, especially significantly increasing cholic acid (CA) levels and decreasing ursodeoxycholic acid (UDCA) levels. Moreover, the protein and mRNA expressions of FXR and FGF15 of T2DM rats were significantly increased, while the expression of CYP7A1 protein in the liver was markedly inhibited by JNDX. Discussion: JNDX can effectively improve insulin resistance, hyperglycemia, hyperlipidemia, and inflammation in T2DM rats. The mechanism is related to its regulation of BAs metabolism and activation of FXR/FGF15 signaling pathway.

CYP8B1 downregulation mediates the metabolic effects of vertical sleeve gastrectomy in mice

BACKGROUND AND AIMS

Although the benefits of vertical sleeve gastrectomy (VSG) surgery are well known, the molecular mechanisms by which VSG alleviates obesity and its complications remain unclear. We aim to determine the role of CYP8B1 (cytochrome P450, family 8, subfamily B, polypeptide 1) in mediating the metabolic benefits of VSG.

APPROACH AND RESULTS

We found that expression of CYP8B1, a key enzyme in controlling the 12α-hydroxylated (12α-OH) bile acid (BA) to non-12α-OH BA ratio, was strongly downregulated after VSG. Using genetic mouse models of CYP8B1 overexpression, knockdown, and knockout, we demonstrated that overexpression of CYP8B1 dampened the metabolic improvements associated with VSG. In contrast, short hairpin RNA-mediated CYP8B1 knockdown improved metabolism similar to those observed after VSG. Cyp8b1 deficiency diminished the metabolic effects of VSG. Further, VSG-induced alterations to the 12α-OH/non-12α-OH BA ratio in the BA pool depended on CYP8B1 expression level. Consequently, intestinal lipid absorption was restricted, and the gut microbiota (GM) profile was altered. Fecal microbiota transplantation from wild type-VSG mice (vs. fecal microbiota transplantation from wild-type-sham mice) improved metabolism in recipient mice, while there were no differences between mice that received fecal microbiota transplantation from knockout-sham and knockout-VSG mice.

CONCLUSIONS

CYP8B1 is a critical downstream target of VSG. Modulation of BA composition and gut microbiota profile by targeting CYP8B1 may provide novel insight into the development of therapies that noninvasively mimic bariatric surgery to treat obesity and its complications.

Research progress on the relationship between bile acid metabolism and type 2 diabetes mellitus

Bile acids, which are steroid molecules originating from cholesterol and synthesized in the liver, play a pivotal role in regulating glucose metabolism and maintaining energy balance. Upon release into the intestine alongside bile, they activate various nuclear and membrane receptors, influencing crucial processes. These bile acids have emerged as significant contributors to managing type 2 diabetes mellitus, a complex clinical syndrome primarily driven by insulin resistance. Bile acids substantially lower blood glucose levels through multiple pathways: BA-FXR-SHP, BA-FXR-FGFR15/19, BA-TGR5-GLP-1, and BA-TGR5-cAMP. They also impact blood glucose regulation by influencing intestinal flora, endoplasmic reticulum stress, and bitter taste receptors. Collectively, these regulatory mechanisms enhance insulin sensitivity, stimulate insulin secretion, and boost energy expenditure. This review aims to comprehensively explore the interplay between bile acid metabolism and T2DM, focusing on primary regulatory pathways. By examining the latest advancements in our understanding of these interactions, we aim to illuminate potential therapeutic strategies and identify areas for future research. Additionally, this review critically assesses current research limitations to contribute to the effective management of T2DM.

Analysis of eight bile acids in urine of gastric cancer patients based on covalent organic framework enrichment coupled with liquid chromatography-tandem mass spectrometry

Gastric carcinoma is one of the most common and deadly forms of cancer. Early detection is critical for successful treatment of gastric cancer, and examination of BAs in urine may provide a critical diagnostic tool for identifying gastric cancer at stages when it can still be cured. Bile acids (BAs) are a crucial toxic factor correlated with the injury of gastric mucosa and as such, quantifying the amount of BA in patient's urine could provide a new means to quickly and non-invasively identify the presence of gastric cancer in the early stages. Here, a covalent organic framework (COF) material synthesized on the basis of 1,3,5-tris(4-nitrophenyl)benzene (TAPB) and pyromellitic dianhydride (PMDA) was used as stationary phase for SPE column that was coupled to LC-MS/MS for quantitative analysis of eight BAs in human urine, including cholic acid (CA), deoxycholic acid (DCA), glycochenodeoxycholic acid (GCDCA), glycocholic acid (GCA), taurochenodeoxycholic acid (TCDCA), lithocholic acid (LCA), hyodeoxycholic acid (HDCA), and chenodeoxycholic acid (CDCA). The enrichment effect of synthesized COF material was better than commercial SPE and HLB column. The sensitivity can increase 9.37- to 54.30- fold (calculated by the ratio of peak area between before and after enrichment). The probable mechanism is due to the great porosity and the similar polarity with BAs of the COF material. By compared with previous literatures, our method had the minimum limit of detection, which achieved 46.40, 25.75, 47.40, 47.37, 30.42, and 33.92 pg /mL, respectively, for GCA, GCDCA, CA, CDCA, HDCA and DCA after enrichment. These eight BAs also accomplished excellent linearity from 0.34 to 10,000 ng/mL. This material was successfully applied in the measurements of these six BAs in human urine from 76 gastric cancer patients and 32 healthy people. Compared to healthy people, levels of CA, CDCA, DCA, and HDCA were significantly elevated and levels of GCDCA were depressed, respectively, in gastric cancer patients. Our work suggests that these acids may act as potential biomarkers for gastric cancer and our framework provides a method for "non-invasive" diagnosis of gastric cancer.

Serum metabolomic analysis of the anti-diabetic effect of Ginseng berry in type II diabetic rats based on ultra high-performance liquid chromatography-high resolution mass spectrometry

Serum metabolomic method was used to investigated the anti-diabetic effects and mechanism of Ginseng berry (GB) on high-fat diet combined streptozotocin induced type II diabetes mellitus (T2DM) rats based on ultra high performance liquid chromatography coupled with quadrupole Exactive orbitrap mass spectrometry (UHPLC-Q-Exactive Orbitrap/MS). Serum samples from control group, T2DM group, metformin treatment group, and GB ginsenoside treatment group rats were collected after intervention. The biochemical parameters of serum were firstly analyzed. Then metabolomic studies based on UHPLC-Q-Exactive Orbitrap/MS and multivariate statistical analysis were performed for the pattern recognition and characteristic metabolites identification. The differential metabolites were analyzed by KEGG metabolic pathway to study the potential mechanism. The treatment of GB ginsenoside significantly reduced the blood glucose level, increased the content of serum SOD, and reduced the content of malondialdehyde. Respectively 16, 9, and 24 differential metabolites were found and identified in T2DM compared to control group, metformin compared to T2DM group and GB compared to T2DM group. Metabolic pathways analysis indicated that GB ginsenoside regulated bile acid metabolism, arachidonic acid metabolism, glucuronization to play a role in the treatment of T2DM. This study verified the anti-diabetic and anti-oxidation effects of ginseng berry, elaborated that GB regulated the secretion of bile acids, activated GLP-1 pathway, increased the secretion of insulin, promoted the hydrolysis of fat and triglyceride, inhibited the activity of 5α - reductase, reduced weight and insulin resistance, so as to improved and treated T2DM, and laid the foundation for the further development and utilization.

Effect of Lactobacillus rhamnosus Probiotic in Early Pregnancy on Plasma Conjugated Bile Acids in a Randomised Controlled Trial

We have previously shown that probiotic supplementation with Lactobacillus rhamnosus HN001 (HN001) led to a reduced incidence of gestational diabetes mellitus (GDM). Here we investigate whether HN001 supplementation resulted in alterations in fasting lipids, insulin resistance, or bile acids (BAs) during pregnancy. Fasting plasma samples collected at 24-30 weeks' gestation, from 348 women randomised at 14-16 weeks' gestation to consume daily probiotic HN001 (n = 172) or a placebo (n = 176) were analysed for lipids, insulin, glucose and BAs. Women supplemented with HN001 had lower fasting glucose compared with placebo (p = 0.040), and lower GDM. Significant differences were found in fasting insulin, HOMA-IR, low density lipoprotein-cholesterol (LDL-c), high density lipoprotein (HDL)-c, triglycerides, total cholesterol, and BAs by GDM status. Lower fasting conjugated BAs were seen in women receiving HN001. A significant decrease of glycocholic acid (GCA) was found in older (age ≥ 35) women who received HN001 (p = 0.005), while GDM women showed significant reduced taurodeoxycholic acid (TDCA) (p = 0.018). Fasting conjugated BA was positively correlated with fasting glucose (r = 0.136, p = 0.020) and fasting insulin (r = 0.113, p = 0.036). Probiotic HN001 supplementation decreases conjugated BAs and might play a role in the improvement of glucose metabolism in women with pregnancy.

Myocardial Infarction and Coronary Artery Disease in Menopausal Women With Type 2 Diabetes Mellitus Negatively Correlate With Total Serum Bile Acids

BACKGROUND

As metabolic molecules, bile acids (BAs) not only promote the absorption of fat-soluble nutrients, but they also regulate many metabolic processes, including the homeostasis of glucose and lipids. Although total serum BA (TBA) measurement is a readily available clinical test related to coronary artery disease (CAD), myocardial infarction (MI), and type 2 diabetes mellitus (T2DM), the relationship between TBA and these pathological conditions remain unclear, and research on this topic is inconclusive.

METHODS

This study enrolled 20,255 menopausal women aged over 50 years, including 6,421 T2DM patients. The study population was divided into different groups according to the median TBA level in order to explore the clinical characteristics of menopausal women with different TBA levels. Spline analyses, generalized additive model (GAM) model and regression analyses based on TBA level were used to explore the relationship between TBA and different diseases independently, including CAD and MI, or in combination with T2DM.

RESULTS

Both in the general population and in the T2DM subgroup, the TBA level was significantly lower in CAD patients than in non-CAD patients. Spline analyses indicated that within normal clinical range of TBA concentration (0-10 µmol/L), the presence of CAD and MI showed similar trends in total and T2DM population. Similarly, the GAM model indicated that within the 0-10 μmol/L clinical range, the predicted probability for CAD and MI alone and in combination with T2DM was negatively correlated with TBA concentration. Multivariate regression analysis suggested that low TBA level was positively associated with the occurrence of CAD combined with T2DM (OR: 1.451; 95%CI: 1.141-1.847).

CONCLUSIONS

In menopausal women, TBA may represent a valuable clinical serum marker with negative correlation for CAD and MI in patients with T2DM.

A higher level of total bile acid in early mid-pregnancy is associated with an increased risk of gestational diabetes mellitus: a prospective cohort study in Wuhan, China

PURPOSE

To assess the longitudinal associations between maternal total bile acid (TBA) levels during early mid-pregnancy and the subsequent risk of gestational diabetes mellitus (GDM).

METHODS

In a prospective cohort study, pregnant women who were enrolled prior to gestational week 16 were followed until delivery. TBA levels were tested during weeks 14-18 of gestation. Using logistic regression, we analyzed the associations between quartiles of TBA and GDM based on a 75-g oral glucose tolerance test (OGTT) at 24-28 gestational weeks.

RESULTS

The GDM rate was 7.9% (114/1441). The mean TBA level was higher in women with GDM than in those without GDM (2.1 ± 2.0 vs 1.5 ± 1.0 µmol/L, P = 0.000). The highest TBA level quartile (2.1-10.7 µmol/L) had a 1.78-fold (95% CI 1.01, 3.14) increased risk of GDM compared with that of the lowest quartile (0.0-0.8 µmol/L) after adjusting for pre-pregnancy body mass index (BMI), gestational, age at TBA test and other confounders. High TBA levels were involved in the fasting glucose level rather than that at 1 h and 2 h after OGTT in all participants.

CONCLUSIONS

Pregnant women with higher serum TBA levels during early mid-pregnancy have a higher risk of developing GDM. TBA may be a new risk factor for GDM.

Quantification of common and planar bile acids in tissues and cultured cells

Bile acids (BAs) have been established as ubiquitous regulatory molecules implicated in a large variety of healthy and pathological processes. However, the scope of BA heterogeneity is often underrepresented in current literature. This is due in part to inadequate detection methods, which fail to distinguish the individual constituents of the BA pool. Thus, the primary aim of this study was to develop a method that would allow the simultaneous analysis of specific C24 BA species, and to apply that method to biological systems of interest. Herein, we describe the generation and validation of an LC-MS/MS assay for quantification of numerous BAs in a variety of cell systems and relevant biofluids and tissue. These studies included the first baseline level assessment for planar BAs, including allocholic acid, in cell lines, biofluids, and tissue in a nonhuman primate (NHP) laboratory animal, Macaca mulatta, in healthy conditions. These results indicate that immortalized cell lines make poor models for the study of BA synthesis and metabolism, whereas human primary hepatocytes represent a promising alternative model system. We also characterized the BA pool of M. mulatta in detail. Our results support the use of NHP models for the study of BA metabolism and pathology in lieu of murine models. Moreover, the method developed here can be applied to the study of common and planar C24 BA species in other systems.

UHPLC/QTOF-MS-based metabolomics reveal the effect of Melastoma dodecandrum extract in type 2 diabetic rats

Context: Melastoma dodecandrum Lour. (Melastomataceae) is a traditional Chinese medicine. This is the first study to report a protective effect of the ethanol extract from M. dodecandrum (MDE) in type 2 diabetic (T2DM) rats.Objective: To investigate the therapeutic mechanism of MDE in T2DM rats.Materials and methods: Sprague-Dawley rats were fed a high-fat diet for 6 consecutive weeks, followed by intraperitoneal injection of streptozotocin (STZ) (30 mg/kg) to induce diabetes. T2DM rats were divided into untreated diabetic, metformin-treated and MDE-treated groups. Additionally, normal rats without treatment served as the control group (n = 6). Metformin (250 mg/kg) and MDE (600 mg/kg) were intragastrically administered to T2DM rats for 5 consecutive weeks. Serum samples were evaluated via ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS), followed by principal components analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA).Results: The 17 identified potential biomarkers were mainly involved in lipid, amino acid, arachidonic acid, taurine and nicotinic acid metabolism. MDE also significantly reduced the level of fasting blood glucose (FBG), oral glucose tolerance, insulin, total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), malondialdehyde (MDA), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and urea nitrogen (BUN) in T2DM rats. The high-density lipoprotein (HDL), serum creatinine (Scr), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) levels were elevated in MDE-treated group.Discussion and conclusion: MDE possesses substantial antidiabetic activity, especially in lipid disorder regulation. This suggests that the use of MDE can be generalized to broader pharmacological studies, such as obesity and hyperlipidaemia.

Mechanism of Dyslipidemia in Obesity-Unique Regulation of Ileal Villus Cell Brush Border Membrane Sodium-Bile Acid Cotransport

In obesity, increased absorption of dietary fat contributes to altered lipid homeostasis. In turn, dyslipidemia of obesity leads to many of the complications of obesity. Bile acids are necessary for the absorption of dietary fat. In the mammalian intestine, apical sodium-dependent bile acid cotransporter (ASBT; SLC10A2) is exclusively responsible for the reabsorption of bile acids in the terminal ileum. In rat and mice models of obesity and importantly in obese humans, ASBT was increased in ileal villus cells. The mechanism of stimulation of ASBT was secondary to an increase in ASBT expression in villus cell brush border membrane. The stimulation of ASBT was not secondary to the altered Na-extruding capacity of villus cells during obesity. Further, increased Farnesoid X receptor (FXR) expression in villus cells during obesity likely mediated the increase in ASBT. Moreover, enhanced FXR expression increased the expression of bile-acid-associated proteins (IBABP and OSTα) that are responsible for handling bile acids absorbed via ASBT in villus cells during obesity. Thus, this study demonstrated that in an epidemic condition, obesity, the dyslipidemia that leads to many of the complications of the condition, may, at least in part, be due to deregulation of intestinal bile acid absorption.

Bile-ology: from bench to bedside

Bile acids (BAs) are originally known as detergents essential for the digestion and absorption of lipids. In recent years, extensive research has unveiled new functions of BAs as gut hormones that modulate physiological and pathological processes, including glucose and lipid metabolism, energy expenditure, inflammation, tumorigenesis, cardiovascular disease, and even the central nervous system in addition to cholesterol homeostasis, enterohepatic protection and liver regeneration. BAs are closely linked with gut microbiota which might explain some of their crucial roles in organs. The signaling actions of BAs can also be mediated through specific nuclear receptors and membrane-bound G protein-coupled receptors. Several pharmacological agents or bariatric surgeries have demonstrated efficacious therapeutic effects on metabolic diseases through targeting BA signaling. In this mini-review, we summarize recent advances in bile-ology, focusing on its translational studies.