Fasting plasma chenodeoxycholic acid and cholic acid concentrations are inversely correlated with insulin sensitivity in adults

Exercise Training Independent of Intensity Lowers Plasma Bile Acids in Prediabetes

INTRODUCTION

People with obesity have high circulating bile acids (BA). Although aerobic fitness favors low circulating BA, the effect of training intensity before clinically meaningful weight loss on BA is unclear. This study aimed to test the hypothesis that 2 wk of interval (INT) versus continuous (CONT) exercise would lower plasma BA in relation to insulin sensitivity.

METHODS

Twenty-three older adults with prediabetes (ADA criteria) were randomized to 12 work-matched bouts of INT ( n = 11, 60.3 ± 2.4 yr, 32.1 ± 1.2 kg·m -2 ) at 3 min at 50% HR peak and 3 min at 90% HR peak or CONT ( n = 12, 60.8 ± 2.4 yr, 34.0 ± 1.7 kg·m -2 ) at 70% HR peak cycling training for 60 min·d -1 over 2 wk. A 180-min 75-g oral glucose tolerance test (OGTT) was performed to assess glucose tolerance (tAUC), insulin sensitivity (Siis), and metabolic flexibility (RER postprandial -RER fast ; indirect calorimetry). BA ( n = 8 conjugated and 7 unconjugated) were analyzed at 0, 30, and 60 min of the OGTT. Anthropometrics and fitness (V̇O 2peak ) were also assessed.

RESULTS

INT and CONT comparably reduced body mass index (BMI; P < 0.001) and fasting RER ( P < 0.001) but raised insulin sensitivity ( P = 0.03). INT increased V̇O 2peak as compared with CONT ( P = 0.01). Exercise decreased the unconjugated BA chenodeoxycholic acid iAUC 60min ( P < 0.001), deoxycholic acid iAUC 60min ( P < 0.001), lithocholic acid iAUC 60min ( P < 0.001), and glycodeoxycholic acid (GCDCA) iAUC 60min ( P < 0.001). Comparable reductions were also seen in the conjugated BA hyodeoxycholic acid iAUC 60min ( P = 0.01) and taurolithocholic acid iAUC 60min ( P = 0.007). Increased V̇O 2peak was associated with lowered UDCA 0min ( r = -0.56, P = 0.02) and cholic acid iAUC 60min ( r = -0.60, P = 0.005), whereas reduced BMI was related to higher GDCA 0min ( r = 0.60, P = 0.005) and GCDCA 0min ( r = 0.53, P = 0.01). Improved insulin sensitivity correlated with lower GCDCA iAUC 60min ( r = -0.45, P = 0.03) and GDCA iAUC 60min ( r = -0.48, P = 0.02), whereas increased metabolic flexibility was related to deoxycholic acid iAUC 60min ( r = 0.64, P = 0.004) and GCDCA iAUC 60min ( r = 0.43, P = 0.05).

CONCLUSIONS

Short-term training lowers some BA in relation to insulin sensitivity independent of intensity.

Reoxygenation Mitigates Intermittent Hypoxia-Induced Systemic Inflammation and Gut Microbiota Dysbiosis in High-Fat Diet-Induced Obese Rats

Background

Obstructive sleep apnea (OSA) is a prevalent sleep breathing disorder characterized by intermittent hypoxia (IH), with continuous positive airway pressure (CPAP) as its standard treatment. However, the effects of intermittent hypoxia/reoxygenation (IH/R) on weight regulation in obesity and its underlying mechanism remain unclear. Gut microbiota has gained attention for its strong association with various diseases. This study aims to explore the combined influence of IH and obesity on gut microbiota and to investigate the impact of reoxygenation on IH-induced alterations.

Methods

Diet-induced obese (DIO) rats were created by 8-week high-fat diet (HFD) feeding and randomly assigned into three groups (n=15 per group): normoxia (NM), IH (6% O2, 30 cycles/h, 8 h/day, 4 weeks), or hypoxia/reoxygenation (HR, 2-week IH followed by 2-week reoxygenation) management. After modeling and exposure, body weight and biochemical indicators were measured, and fecal samples were collected for 16S rRNA sequencing.

Results

DIO rats in the IH group showed increased weight gain (p=0.0016) and elevated systemic inflammation, including IL-6 (p=0.0070) and leptin (p=0.0004). Moreover, IH rats exhibited greater microbial diversity (p<0.0167), and significant alterations in the microbial structure (p=0.014), notably the order Clostridiales, accompanied by an upregulation of bile acid metabolism predicted pathway (p=0.0043). Reoxygenation not only improved IH-exacerbated obesity, systemic inflammation, leptin resistance, and sympathetic activation, but also showed the potential to restore IH-induced microbial alterations. Elevated leptin levels were associated with Ruminococcaceae (p=0.0008) and Clostridiales (p=0.0019), while body weight was linked to Blautia producta (p=0.0377). Additionally, the abundance of Lactobacillus was negatively correlated with leptin levels (p=0.0006) and weight (p=0.0339).

Conclusion

IH leads to gut dysbiosis and metabolic disorders, while reoxygenation therapy demonstrates a potentially protective effect by restoring gut homeostasis and mitigating inflammation. It highlights the potential benefits of CPAP in reducing metabolic risk among obese patients with OSA.

Bile acid metabolism and signaling in health and disease: molecular mechanisms and therapeutic targets

Bile acids, once considered mere dietary surfactants, now emerge as critical modulators of macronutrient (lipid, carbohydrate, protein) metabolism and the systemic pro-inflammatory/anti-inflammatory balance. Bile acid metabolism and signaling pathways play a crucial role in protecting against, or if aberrant, inducing cardiometabolic, inflammatory, and neoplastic conditions, strongly influencing health and disease. No curative treatment exists for any bile acid influenced disease, while the most promising and well-developed bile acid therapeutic was recently rejected by the FDA. Here, we provide a bottom-up approach on bile acids, mechanistically explaining their biochemistry, physiology, and pharmacology at canonical and non-canonical receptors. Using this mechanistic model of bile acids, we explain how abnormal bile acid physiology drives disease pathogenesis, emphasizing how ceramide synthesis may serve as a unifying pathogenic feature for cardiometabolic diseases. We provide an in-depth summary on pre-existing bile acid receptor modulators, explain their shortcomings, and propose solutions for how they may be remedied. Lastly, we rationalize novel targets for further translational drug discovery and provide future perspectives. Rather than dismissing bile acid therapeutics due to recent setbacks, we believe that there is immense clinical potential and a high likelihood for the future success of bile acid therapeutics.

Understanding the gastrointestinal tract in obesity: From gut motility patterns to enzyme secretion

BACKGROUND AND PURPOSE

The pathophysiology of obesity has been the product of extensive research, revealing multiple interconnected mechanisms contributing to body weight regulation. The regulation of energy balance involves an intricate network, including the gut-neuroendocrine interplay. As a consequence, research on the gut-brain-microbiota axis in obesity has grown extensively. The physiology of the gastrointestinal tract, far from being underexplored, has significant implications for the development of specific complications in people living with obesity across the fields of gastroenterology, nutrition, and pharmacology. Clinical research indicates higher fasting bile acids serum levels, and blunted postprandial increases in bilious secretions in people living with obesity. Findings are less straightforward for the impact of obesity on gastric emptying with various studies reporting accelerated, normal, or delayed gastric emptying rates. Conversely, the effect of obesity on gastrointestinal pH, gastrointestinal transit, and gastric and pancreatic enzyme secretion is largely unknown. In this review, we explore the current evidence on the gastrointestinal physiology of obesity.

Serum bile acid measurements in women of European and South Asian ethnicity with or without gestational diabetes mellitus: A cohort study

OBJECTIVE

Investigation of serum bile acid profiles in pregnancies complicated by gestational diabetes mellitus (GDM) in a multi-ethnic cohort of women who are lean or obese.

DESIGN

Prospective cohort study.

SETTING

UK multicentre study.

POPULATION

Fasting serum from participants of European or South Asian self-reported ethnicity from the PRiDE study, between 23 and 31 weeks of gestation.

METHODS

Bile acids were measured using ultra-performance liquid chromatography-tandem mass spectrometry. Log-transformed data were analysed using linear regression in STATA/IC 15.0.

MAIN OUTCOME MEASURES

Total bile acids (TBAs), C4, fasting glucose and insulin.

RESULTS

The TBAs were 1.327-fold (1.105-1.594) increased with GDM in European women (P = 0.003). Women with GDM had 1.162-fold (1.002-1.347) increased levels of the BA synthesis marker C4 (P = 0.047). In South Asian women, obesity (but not GDM) increased TBAs 1.522-fold (1.193-1.942, P = 0.001). Obesity was associated with 1.420-fold (1.185-1.702) increased primary/secondary BA ratio (P < 0.001) related to 1.355-fold (1.140-1.611) increased primary BA concentrations (P = 0.001). TBAs were positively correlated with fasting glucose (P = 0.039) in all women, and with insulin (P = 0.001) and the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (P = 0.001) in women with GDM.

CONCLUSIONS

Serum BA homeostasis in late gestation depends on body mass index and GDM in ethnicity-specific ways. This suggests ethnicity-specific aetiologies may contribute to metabolic risk in European and South Asian women, with the relationship between BAs and insulin resistance of greater importance in European women. Further studies into ethnicity-specific precision medicine for GDM are required.

Bile salt signaling and bile salt-based therapies in cardiometabolic disease

Bile salts have an established role in the emulsification and intestinal absorption of dietary lipids, and their homeostasis is tightly controlled by various transporters and regulators in the enterohepatic circulation. Notably, emerging evidence points toward bile salts as major modulators of cardiometabolic disease (CMD), an umbrella disease of disorders affecting the heart and blood vessels that is caused by systemic metabolic diseases such as Type 2 diabetes mellitus (T2DM) and metabolic dysfunction-associated steatotic liver disease (MASLD), the latter encompassing also metabolic dysfunction-associated steatohepatitis (MASH). The underlying mechanisms of protective effects of bile salts are their hormonal properties, enabling them to exert versatile metabolic effects by activating various bile salt-responsive signaling receptors with the nuclear farnesoid X receptor (FXR) and the Takeda G-protein-coupled receptor 5 (TGR5) as most extensively investigated. Activation of FXR and TGR5 is involved in the regulation of glucose, lipid and energy metabolism, and inflammation. Bile salt-based therapies directly targeting FXR and TGR5 signaling have been evaluated for their therapeutic potential in CMD. More recently, therapeutics targeting bile salt transporters thereby modulating bile salt localization, dynamics, and signaling, have been developed and evaluated in CMD. Here, we discuss the current knowledge on the contribution of bile salt signaling in the pathogenesis of CMD and the potential of bile salt-based therapies for the treatment of CMD.

Circulating bile acid profile characteristics in PCOS patients and the role of bile acids in predicting the pathogenesis of PCOS

Background

The metabolic profile of bile acids and their potential role as biomarkers in the pathogenesis of polycystic ovary syndrome (PCOS) have not been thoroughly characterized. Assessing their predictive value for PCOS is of significant importance.

Methods

In this study, we enrolled 408 women with PCOS and 204 non-PCOS controls. The serum bile acid profile was measured using high-performance liquid chromatography-tandem mass spectrometry (LC/MS). We analyzed the differences in serum bile acid profiles between PCOS patients using the OPLS-DA model. Additionally, we examined the relationship between bile acid profiles and parameters related to glucose metabolism and hyperandrogenism. ROC analysis was employed to identify potential biomarkers for PCOS pathogenesis. XGboost was utilized for cross-validation.

Results

The bile acid profile was found to be altered in PCOS patients. Specifically, the primary and secondary unconjugated bile acid fractions were significantly higher in the PCOS population. We identified five bile acid metabolite candidates that exhibited the most significant differences between PCOS and non-PCOS controls. DCA was associated with deposition index, fasting and postprandial insulin but was influenced by testosterone. CDCA and LCA combined with testosterone showed potential as biomarkers for the pathogenesis of PCOS.

Conclusion

The circulating bile acid profile undergoes changes in PCOS. DCA is associated with deposition index, fasting and postprandial insulin and its level is influenced by testosterone. CDCA and LCA combined with testosterone have the potential to serve as biomarkers for the pathogenesis of PCOS.

State of art on the mechanisms of laparoscopic sleeve gastrectomy in treating type 2 diabetes mellitus

Obesity and type-2 diabetes mellitus (T2DM) are metabolic disorders. Obesity increases the risk of T2DM, and as obesity is becoming increasingly common, more individuals suffer from T2DM, which poses a considerable burden on health systems. Traditionally, pharmaceutical therapy together with lifestyle changes is used to treat obesity and T2DM to decrease the incidence of comorbidities and all-cause mortality and to increase life expectancy. Bariatric surgery is increasingly replacing other forms of treatment of morbid obesity, especially in patients with refractory obesity, owing to its many benefits including good long-term outcomes and almost no weight regain. The bariatric surgery options have markedly changed recently, and laparoscopic sleeve gastrectomy (LSG) is gradually gaining popularity. LSG has become an effective and safe treatment for type-2 diabetes and morbid obesity, with a high cost-benefit ratio. Here, we review the me-chanism associated with LSG treatment of T2DM, and we discuss clinical studies and animal experiments with regard to gastrointestinal hormones, gut microbiota, bile acids, and adipokines to clarify current treatment modalities for patients with obesity and T2DM.

Multimodal plasma metabolomics and lipidomics in elucidating metabolic perturbations in tuberculosis patients with concurrent type 2 diabetes

Type 2 diabetes mellitus (DM) poses a major burden for the treatment and control of tuberculosis (TB). Characterization of the underlying metabolic perturbations in DM patients with TB infection would yield insights into the pathophysiology of TB-DM, thus potentially leading to improvements in TB treatment. In this study, a multimodal metabolomics and lipidomics workflow was applied to investigate plasma metabolic profiles of patients with TB and TB-DM. Significantly different biological processes and biomarkers in TB-DM vs. TB were identified using a data-driven, knowledge-based framework. Changes in metabolic and signaling pathways related to carbohydrate and amino acid metabolism were mainly captured by amide HILIC column metabolomics analysis, while perturbations in lipid metabolism were identified by the C18 metabolomics and lipidomics analysis. Compared to TB, TB-DM exhibited elevated levels of bile acids and molecules related to carbohydrate metabolism, as well as the depletion of glutamine, retinol, lysophosphatidylcholine, and phosphatidylcholine. Moreover, arachidonic acid metabolism was determined as a potential important factor in the interaction between TB and DM pathophysiology. In a correlation network of the significantly altered molecules, among the central nodes, chenodeoxycholic acid was robustly associated with TB and DM. Fatty acid (22:4) was a component of all significant modules. In conclusion, the integration of multimodal metabolomics and lipidomics provides a thorough picture of the metabolic changes associated with TB-DM. The results obtained from this comprehensive profiling of TB patients with DM advance the current understanding of DM comorbidity in TB infection and contribute to the development of more effective treatment.

The Role of the Gut Microbiome and Trimethylamine Oxide in Atherosclerosis and Age-Related Disease

The gut microbiome plays a major role in human health, and gut microbial imbalance or dysbiosis is associated with disease development. Modulation in the gut microbiome can be used to treat or prevent different diseases. Gut dysbiosis increases with aging, and it has been associated with the impairment of gut barrier function leading to the leakage of harmful metabolites such as trimethylamine (TMA). TMA is a gut metabolite resulting from dietary amines that originate from animal-based foods. TMA enters the portal circulation and is oxidized by the hepatic enzyme into trimethylamine oxide (TMAO). Increased TMAO levels have been reported in elderly people. High TMAO levels are linked to peripheral artery disease (PAD), endothelial senescence, and vascular aging. Emerging evidence showed the beneficial role of probiotics and prebiotics in the management of several atherogenic risk factors through the remodeling of the gut microbiota, thus leading to a reduction in TMAO levels and atherosclerotic lesions. Despite the promising outcomes in different studies, the definite mechanisms of gut dysbiosis and microbiota-derived TMAO involved in atherosclerosis remain not fully understood. More studies are still required to focus on the molecular mechanisms and precise treatments targeting gut microbiota and leading to atheroprotective effects.

Circulating Bile Acids as Biomarkers for Disease Diagnosis and Prevention

CONTEXT

Bile acids (BAs) are pivotal signaling molecules that regulate energy metabolism and inflammation. Recent epidemiological studies have reported specific alterations in circulating BA profiles in certain disease states, including obesity, type 2 diabetes mellitus (T2DM), nonalcoholic fatty liver disease (NAFLD), and Alzheimer disease (AD). In the past decade, breakthroughs have been made regarding the translation of BA profiling into clinical use for disease prediction. In this review, we summarize and synthesize recent data on variation in circulating BA profiles in patients with various diseases to evaluate the value of these biomarkers in human plasma for early diagnosis.

EVIDENCE ACQUISITION

This review is based on a collection of primary and review literature gathered from a PubMed search for BAs, obesity, T2DM, insulin resistance (IR), NAFLD, hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), colon cancer, and AD, among other keywords.

EVIDENCE SYNTHESIS

Individuals with obesity, T2DM, HCC, CCA, or AD showed specific alterations in circulating BA profiles. These alterations may have existed long before the initial diagnosis of these diseases. The intricate relationship between obesity, IR, and NAFLD complicates the establishment of clear and independent associations between BA profiles and nonalcoholic steatohepatitis. Alterations in the levels of total BAs and several BA species were seen across the entire spectrum of NAFLD, demonstrating significant increases with the worsening of histological features.

CONCLUSIONS

Aberrant circulating BA profiles are an early event in the onset and progression of obesity, T2DM, HCC, and AD. The pleiotropic effects of BAs explain these broad connections. Circulating BA profiles could provide a basis for the development of biomarkers for the diagnosis and prevention of a wide range of diseases.

Bile acids and microbes in metabolic disease

Bile acids (BAs) serve as physiological detergents that enable the intestinal absorption and transportation of nutrients, lipids and vitamins. BAs are primarily produced by humans to catabolize cholesterol and play crucial roles in gut metabolism, microbiota habitat regulation and cell signaling. BA-activated nuclear receptors regulate the enterohepatic circulation of BAs which play a role in energy, lipid, glucose, and drug metabolism. The gut microbiota plays an essential role in the biotransformation of BAs and regulates BAs composition and metabolism. Therefore, altered gut microbial and BAs activity can affect human metabolism and thus result in the alteration of metabolic pathways and the occurrence of metabolic diseases/syndromes, such as diabetes mellitus, obesity/hypercholesterolemia, and cardiovascular diseases. BAs and their metabolites are used to treat altered gut microbiota and metabolic diseases. This review explores the increasing body of evidence that links alterations of gut microbial activity and BAs with the pathogenesis of metabolic diseases. Moreover, we summarize existing research on gut microbes and BAs in relation to intracellular pathways pertinent to metabolic disorders. Finally, we discuss how therapeutic interventions using BAs can facilitate microbiome functioning and ease metabolic diseases.

Sacubitril/Valsartan contributes to improving the diabetic kidney disease and regulating the gut microbiota in mice

Background

Diabetic kidney disease (DKD), as a serious microvascular complication of diabetes, has limted treatment options. It is reported that the Sacubitril/Valsartan (Sac/Val) can improve kidney function, and the disordered gut microbiota and part of its metabolites are related to the development of DKD. Therefore, we aim to explore whether the effect of Sac/Val on DKD is associated with the gut microbiota and related plasma metabolic profiles.

Methods

Male C57BL/6J mice were randomly divided into 3 groups: Con group (n = 5), DKD group (n = 6), and Sac/Val group (n = 6) . Sac/Val group was treated with Sac/Val solution. The intervention was given once every 2 days for 6 weeks. We measured the blood glucose and urine protein level of mice at different times. We then collected samples at the end of experiment for the 16s rRNA gene sequencing analysis and the untargeted plasma metabonomic analysis.

Results

We found that the plasma creatinine concentration of DKD-group mice was significantly higher than that of Con-group mice, whereas it was reduced after the Sac/Val treatment. Compared with DKD mice, Sac/Val treatment could decrease the expression of indicators related to EndMT and renal fibrosis like vimentin, collagen IV and fibronectin in kidney. According to the criteria of LDA ≥ 2.5 and p<0.05, LefSe analysis of gut microbiota identified 13 biomarkers in Con group, and 33 biomarkers in DKD group, mainly including Prevotella, Escherichia_Shigella and Christensenellaceae_R_7_group, etc. For the Sac/Val group, there were 21 biomarkers, such as Bacteroides, Rikenellaceae_RC9_gut_group, Parabacteroides, Lactobacillus, etc. Plasma metabolomics analysis identified a total of 648 metabolites, and 167 important differential metabolites were screened among groups. KEGG pathway of tryptophan metabolism: M and bile secretion: OS had the highest significance of enrichment.

Conclusions

Sac/Val improves the renal function of DKD mice by inhibiting renal fibrosis. This drug can also regulate gut microbiota in DKD mice.

The role of the gut microbiota in health and cardiovascular diseases

The gut microbiota is critical to human health, such as digesting nutrients, forming the intestinal epithelial barrier, regulating immune function, producing vitamins and hormones, and producing metabolites to interact with the host. Meanwhile, increasing evidence indicates that the gut microbiota has a strong correlation with the occurrence, progression and treatment of cardiovascular diseases (CVDs). In patients with CVDs and corresponding risk factors, the composition and ratio of gut microbiota have significant differences compared with their healthy counterparts. Therefore, gut microbiota dysbiosis, gut microbiota-generated metabolites, and the related signaling pathway may serve as explanations for some of the mechanisms about the occurrence and development of CVDs. Several studies have also demonstrated that many traditional and latest therapeutic treatments of CVDs are associated with the gut microbiota and its generated metabolites and related signaling pathways. Given that information, we summarized the latest advances in the current research regarding the effect of gut microbiota on health, the main cardiovascular risk factors, and CVDs, highlighted the roles and mechanisms of several metabolites, and introduced corresponding promising treatments for CVDs regarding the gut microbiota. Therefore, this review mainly focuses on exploring the role of gut microbiota related metabolites and their therapeutic potential in CVDs, which may eventually provide better solutions in the development of therapeutic treatment as well as the prevention of CVDs.

Uygur type 2 diabetes patient fecal microbiota transplantation disrupts blood glucose and bile acid levels by changing the ability of the intestinal flora to metabolize bile acids in C57BL/6 mice

BACKGROUND

Our epidemiological study showed that the intestinal flora of Uygur T2DM patients differed from that of normal glucose-tolerant people. However, whether the Uygur T2DM fecal microbiota transplantation could reproduce the glucose metabolism disorder and the mechanism behind has not been reported. This study was designed to explore whether Uygur T2DM fecal microbiota transplantation could reproduce the glucose metabolism disorder and its mechanism.

METHODS

The normal diet and high fat diet group consisted of C57BL/6 mice orally administered 0.2 mL sterile normal saline. For the MT (microbiota transplantation) intervention groups, C57BL/6 mice received oral 0.2 mL faecal microorganisms from Uygur T2DM. All mice were treated daily for 8 weeks and Blood glucose levels of mice were detected. Mice faecal DNA samples were sequenced and quantified using 16S rDNA gene sequencing. Then we detected the ability of the intestinal flora to metabolize bile acids (BAs) through co-culture of fecal bacteria and BAs. BA levels in plasma were determined by UPLC-MS. Further BA receptors and glucagon-like peptide-1 (GLP-1) expression levels were determined with RT-q PCR and western blotting.

RESULTS

MT impaired insulin and oral glucose tolerance. Deoxycholic acid increased and tauro-β-muricholic acid and the non-12-OH BA:12-OH BA ratio decreased in plasma. MT improved the ability of intestinal flora to produce deoxycholic acid. Besides, the vitamin D receptor in the liver and ileum and GLP-1 in the ileum decreased significantly.

CONCLUSIONS

Uygur T2DM fecal microbiota transplantation disrupts glucose metabolism by changing the ability of intestinal flora to metabolize BAs and the BAs/GLP-1 pathway.

Metabolic characterization of human intraocular fluid in patients with pathological myopia

Pathological myopia (PM) and its associated complications can lead to permanent vision loss. However, the cellular mechanisms underlying PM development remain unclear. To identify the metabolic alterations that may contribute to the pathophysiology of PM, we performed non-targeted metabolomics analysis using ultra-high-performance liquid chromatography with tandem mass spectrometry in age- and sex-matched patients with PM (n = 30) and individuals without myopia as controls (n = 30). Targeted metabolomics and insulin microarray were used to validate the results. We identified 508 metabolites in the aqueous humour (AH) and 601 in the vitreous humour (VH). Statistical evaluation revealed that 104 metabolites in AH and 114 metabolites in VH were significantly different between the two groups (variable important for the projection >1, fold change >1.5, or < 0.667, and P < 0.05). The four metabolic pathways enriched in both AH and VH identified to be associated with PM were: bile secretion, insulin secretion, thyroid hormone synthesis, and cGMP-PKG signaling pathway. The concentration of 10 amino acids was significantly higher in the PM than in the controls. Insulin microarray analysis showed that insulin, insulin-like growth factor 2 (IGF-2), IGF-2R, insulin-like growth factor binding protein 1 (IGFBP-1), IGFBP-2, IGFBP-3, IGFBP-4, and IGFBP-6 levels were significantly higher in PM patients compared to that in the controls. Thus, this study identified potential metabolite biomarkers for PM and provided novel insights into the mechanisms underlying this disorder.

Serum and cecal metabolic profile of the insulin resistant and dyslipidemic p47phox knockout mice

Involvement of NOX-dependent oxidative stress in the pathophysiology of metabolic disorders as well as in the maintenance of metabolic homeostasis has been demonstrated previously. In the present study, the metabolic profile in p47^phox-/- and WT mice fed on a chow diet was evaluated to assess the role of metabolites in glucose intolerance and dyslipidemia under altered oxidative stress conditions. p47^phox-/- mice displayed glucose intolerance, dyslipidemia, hyperglycemia, insulin resistance (IR), hyperinsulinemia, and altered energy homeostasis without any significant change in gluconeogenesis. The expression of genes involved in lipid synthesis and uptake was enhanced in the liver, adipose tissue, and intestine tissues. Similarly, the expression of genes associated with lipid efflux in the liver and intestine was also enhanced. Enhanced gut permeability, inflammation, and shortening of the gut was evident in p47^phox-/- mice. Circulating levels of pyrimidines, phosphatidylglycerol lipids, and 3-methyl-2-oxindole were augmented, while level of purine was reduced in the serum. Moreover, the cecal metabolome was also altered, as was evident with the increase in indole-3-acetamide, N-acetyl galactosamine, glycocholate, and a decrease in hippurate, indoxyl sulfate, and indigestible sugars (raffinose and melezitose). Treatment of p47^phox-/- mice with pioglitazone, marginally improved glucose intolerance, and dyslipidemia, with an increase in PUFAs (linoleate, docosahexaenoic acid, and arachidonic acid). Overall, the results obtained in p47^phox-/- mice indicate an association of IR and dyslipidemia with altered serum and cecal metabolites (both host and bacterial-derived), implying a critical role of NOX-derived ROS in metabolic homeostasis.

Effect of tetra-hydroxylated bile acid on size and insulin sensitivity of subcutaneous adipocytes in healthy lean cats

Obesity leads to insulin resistance and is a major risk factor for the development of diabetes mellitus in cats. Prevention of obesity and obesity-induced insulin resistance is difficult, and reliable long-term strategies are currently lacking. Retinoid-related orphan receptor gamma (RORγ) was recently identified as an important transcription factor in the development of large insulin-resistant adipocytes in mice and humans. RORγ negatively affects adipocyte differentiation through expression of its target gene matrix metalloproteinase 3 (MMP3) and promotes the development of large insulin-resistant adipocytes. Preliminary studies in mice showed that RORγ can be inhibited by its ligand tetra-hydroxylated bile acid (THBA). In the present study, serum THBA levels were determined in healthy and diabetic cats. Moreover, potential side effects and the effects of THBA supplementation on adipocyte size, mRNA expression of RORγ, MMP3, interleukin 6, tumor necrosis factor α, adiponectin and leptin in feline subcutaneous adipocytes and insulin sensitivity were investigated in healthy normal weight cats. Thirteen healthy and 13 diabetic cats were used for determination of serum THBA level, and six healthy normal-weight cats were included in a feeding trial. Similar THBA levels were determined in serum of healthy and diabetic cats. Supplementation of 5 mg/kg THBA for 8 wk did not cause any negative effect on feeding behavior, general condition and blood parameters of tested cats. It significantly reduced adipocyte size and mRNA expression of MMP3, interleukin 6, and tumor necrosis factor α in adipocytes, while mRNA expression of adiponectin significantly increased and mRNA expression of RORγ and leptin remained unchanged. Administration of THBA did not influence fasting blood glucose levels or the response of cats to acute insulin administration. Based on these results, THBA is palatable and is considered safe for use in cats. It reduces expression of MMP3 and promotes the development of small adipocytes with increased expression of adiponectin and reduced expression of interleukin 6 and tumor necrosis factor α. Further studies are recommended to evaluate the effect of THBA on adipocyte size and insulin sensitivity in obese cats.

Abnormal bile acid-microbiota crosstalk promotes the development of hepatocellular carcinoma

Background

Gut microbiota and microbe-derived metabolites are involved in the development of HCC. Bile acids (BAs) are the most important gut microbiota-modulated endogenous signaling molecules.

Methods

We tested serum bile acid levels and gut microbiome compositions in patients with HCC, chemical-induced HCC mouse models (DEN-HCC mice) and mouse orthotopic implanted liver tumor models with vancomycin treatment (vancomycin-treated mice). Then, we screened an important kind of HCC-related BAs, and verified its effect on the growth of HCC in vivo and in vitro.

Results

We found that the remarkably decreasing percentages of serum secondary BAs in the total bile acids of patients and DEN-HCC mice, especially, conjugated deoxycholic acids (DCA). The relative abundance of the bile salt hydrolase (BSH)-rich bacteria (Bifidobacteriales, Lactobacillales, Bacteroidales, and Clostridiales) was decreased in the feces of patients and DEN-HCC mice. Then, in vancomycin-treated mice, vancomycin treatment induced a reduction in the BSH-rich bacteria and promoted the growth of liver tumors. Similarly, the percentage of conjugated DCA after vancomycin treatment was significantly declined. We used a kind of conjugated DCA, Glyco-deoxycholic acid (GDCA), and found that GDCA remarkably inhibited the growth of HCC in vivo and in vitro.

Conclusions

We conclude that the remarkably decreasing percentages of serum conjugated DCA may be closely associated with HCC, which may be induced by the reducing gut BSH-rich bacteria. The mechanisms may be correlated with conjugated DCA directly inhibiting the growth and migration of HCC cells.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12072-022-10299-7.

Plasma Levels of Bile Acids Are Related to Cardiometabolic Risk Factors in Young Adults

CONTEXT

Bile acids (BA) are known for their role in intestinal lipid absorption and can also play a role as signaling molecules to control energy metabolism. Prior evidence suggests that alterations in circulating BA levels and in the pool of circulating BA are linked to an increased risk of obesity and a higher incidence of type 2 diabetes in middle-aged adults.

OBJECTIVE

We aimed to investigate the association between plasma levels of BA with cardiometabolic risk factors in a cohort of well-phenotyped, relatively healthy young adults.

METHODS

Body composition, brown adipose tissue, serum classical cardiometabolic risk factors, and a set of 8 plasma BA (including glyco-conjugated forms) in 136 young adults (age 22.1 ± 2.2 years, 67% women) were measured.

RESULTS

Plasma levels of chenodeoxycholic acid (CDCA) and glycoursodeoxycholic acid (GUDCA) were higher in men than in women, although these differences disappeared after adjusting for body fat percentage. Furthermore, cholic acid (CA), CDCA, deoxycholic acid (DCA), and glycodeoxycholic acid (GDCA) levels were positively, yet weakly associated, with lean body mass (LBM) levels, while GDCA and glycolithocholic acid (GLCA) levels were negatively associated with 18F-fluorodeoxyglucose uptake by brown adipose tissue. Interestingly, glycocholic acid (GCA), glycochenodeoxycholic acid (GCDCA), and GUDCA were positively associated with glucose and insulin serum levels, HOMA index, low-density lipoprotein cholesterol, tumor necrosis factor alpha, interleukin (IL)-2, and IL-8 levels, but negatively associated with high-density lipoprotein cholesterol, ApoA1, and adiponectin levels, yet these significant correlations partially disappeared after the inclusion of LBM as a confounder.

CONCLUSION

Our findings indicate that plasma levels of BA might be sex dependent and are associated with cardiometabolic and inflammatory risk factors in young and relatively healthy adults.

Vancomycin-Induced Modulation of Gram-Positive Gut Bacteria and Metabolites Remediates Insulin Resistance in iNOS Knockout Mice

The role of oxidative and nitrosative stress has been implied in both physiology and pathophysiology of metabolic disorders. Inducible nitric oxide synthase (iNOS) has emerged as a crucial regulator of host metabolism and gut microbiota activity. The present study examines the role of the gut microbiome in determining host metabolic functions in the absence of iNOS. Insulin-resistant and dyslipidemic iNOS-/- mice displayed reduced microbial diversity, with a higher relative abundance of Allobaculum and Bifidobacterium, gram-positive bacteria, and altered serum metabolites along with metabolic dysregulation. Vancomycin, which largely depletes gram-positive bacteria, reversed the insulin resistance (IR), dyslipidemia, and related metabolic anomalies in iNOS-/- mice. Such improvements in metabolic markers were accompanied by alterations in the expression of genes involved in fatty acid synthesis in the liver and adipose tissue, lipid uptake in adipose tissue, and lipid efflux in the liver and intestine tissue. The rescue of IR in vancomycin-treated iNOS-/- mice was accompanied with the changes in select serum metabolites such as 10-hydroxydecanoate, indole-3-ethanol, allantoin, hippurate, sebacic acid, aminoadipate, and ophthalmate, along with improvement in phosphatidylethanolamine to phosphatidylcholine (PE/PC) ratio. In the present study, we demonstrate that vancomycin-mediated depletion of gram-positive bacteria in iNOS-/- mice reversed the metabolic perturbations, dyslipidemia, and insulin resistance.

Gut microbiota: a potential target for traditional Chinese medicine intervention in coronary heart disease

Coronary heart disease (CHD) is a common ischaemic heart disease whose pathological mechanism has not been fully elucidated. Single target drugs, such as antiplatelet aggregation, coronary artery dilation and lipid-lowering medicines, can relieve some symptoms clinically but cannot effectively prevent and treat CHD. Accumulating evidence has revealed that alterations in GM composition, diversity, and richness are associated with the risk of CHD. The metabolites of the gut microbiota (GM), including trimethylamine N-oxide (TMAO), short-chain fatty acids (SCFAs) and bile acids (BAs), affect human physiology by activating numerous signalling pathways. Due to the advantage of multiple components and multiple targets, traditional Chinese medicine (TCM) can intervene in CHD by regulating the composition of the GM, reducing TMAO, increasing SCFAs and other CHD interventions. We have searched PubMed, Web of science, Google Scholar Science Direct, and China National Knowledge Infrastructure (CNKI), with the use of the keywords "gut microbiota, gut flora, traditional Chinese medicine, herbal medicine, coronary heart disease". This review investigated the relationship between GM and CHD, as well as the intervention of TCM in CHD and GM, and aims to provide valuable insights for the treatments of CHD by TCM.

Circulating Bile Acid Profiles: A Need for Further Examination

CONTEXT

Bile acids (BAs) are increasingly recognized as metabolic and chronobiologic integrators that synchronize the systemic metabolic response to nutrient availability. Alterations in the concentration and/or composition of circulating BAs are associated with a number of metabolic disorders, such as obesity, type 2 diabetes mellitus (T2DM), insulin resistance (IR), and metabolic associated fatty liver disease (MAFLD). This review summarizes recent evidence that links abnormal circulating BA profiles to multiple metabolic disorders, and discusses the possible mechanisms underlying the connections to determine the role of BA profiling as a novel biomarker for these abnormalities.

EVIDENCE ACQUISITION

The review is based on a collection of primary and review literature gathered from a PubMed search of BAs, T2DM, IR, and MAFLD, among other keywords.

EVIDENCE SYNTHESIS

Obese and IR subjects appear to have elevated fasting circulating BAs but lower postprandial increase when compared with controls. The possible underlying mechanisms are disruption in the synchronization between the feeding/fasting cycle and the properties of BA-regulated metabolic pathways. Whether BA alterations are associated per se with MAFLD remains inconclusive. However, increased fasting circulating BAs level was associated with higher risk of advanced fibrosis stage. Thus, for patients with MAFLD, dynamically monitoring the circulating BA profiles may be a promising tool for the stratification of MAFLD.

CONCLUSIONS

Alterations in the concentration, composition, and rhythm of circulating BAs are associated with adverse events in systemic metabolism. Subsequent investigations regarding these aspects of circulating BA kinetics may help predict future metabolic disorders and guide therapeutic interventions.

Preconception insulin resistance and neonatal birth weight in women with obesity: role of bile acids

RESEARCH QUESTION

Does maternal preconception insulin resistance affect neonatal birth weight among women with obesity? Is insulin resistance associated with circulating bile acids? Do bile acids influence the association between maternal preconception insulin resistance and neonatal birth weight?

DESIGN

An exploratory post-hoc analysis of the LIFEstyle randomized controlled trial comparing lifestyle intervention with conventional infertility treatment in women with a BMI of ≥29 kg/m². Fasting blood samples were collected at randomization and after 3 and 6 months in 469 women. Insulin resistance was quantified using the homeostasis model assessment of insulin resistance (HOMA-IR). Bile acid sub-species were determined by liquid chromatography with tandem mass spectrometry. Singletons were included (n = 238). Birth weight Z-scores were adjusted for age, offspring gender and parity. Multilevel analysis and linear regressions were used.

RESULTS

A total of 913 pairs of simultaneous preconception HOMA-IR (median [Q25; Q75]: 2.96 [2.07; 4.16]) and total bile acid measurements (1.79 [1.10; 2.94]) µmol/l were taken. Preconception HOMA-IR was positively associated with total bile acids (adjusted B 0.15; 95% CI 0.09 to 0.22; P < 0.001) and all bile acid sub-species. At the last measurement before pregnancy, HOMA-IR (2.71 [1.91; 3.74]) was positively related to birth weight Z-score (mean ± SD 0.4 ± 1.1; adjusted B 0.08; 95% CI 0.01 to 0.14; P = 0.03). None of the preconception bile acids measured were associated with birth weight.

CONCLUSION

Maternal preconception insulin resistance is an important determinant of neonatal birth weight in women with obesity, whereas preconception bile acids are not.

Chenodeoxycholic Acid Pharmacology in Biotechnology and Transplantable Pharmaceutical Applications for Tissue Delivery: An Acute Preclinical Study

INTRODUCTION

Primary bile acids (PBAs) are produced and released into human gut as a result of cholesterol catabolism in the liver. A predominant PBA is chenodeoxycholic acid (CDCA), which in a recent study in our laboratory, showed significant excipient-stabilizing effects on microcapsules carrying insulinoma β-cells, in vitro, resulting in improved cell functions and insulin release, in the hyperglycemic state. Hence, this study aimed to investigate the applications of CDCA in bio-encapsulation and transplantation of primary healthy viable islets, preclinically, in type 1 diabetes.

METHODS

Healthy islets were harvested from balb/c mice, encapsulated in CDCA microcapsules, and transplanted into the epididymal tissues of 6 syngeneic diabetic mice, post diabetes confirmation. Pre-transplantation, the microcapsules' morphology, size, CDCA-deep layer distribution, and physical features such as swelling ratio and mechanical strength were analyzed. Post-transplantation, animals' weight, bile acids', and proinflammatory biomarkers' concentrations were analyzed. The control group was diabetic mice that were transplanted encapsulated islets (without PBA).

RESULTS AND CONCLUSION

Islet encapsulation by PBA microcapsules did not compromise the microcapsules' morphology or features. Furthermore, the PBA-graft performed better in terms of glycemic control and resulted in modulation of the bile acid profile in the brain. This is suggestive that the improved glycemic control was mediated via brain-related effects. However, the improvement in graft insulin delivery and glycemic control was short-term.

Impact of Gut Microbiota and Microbiota-Related Metabolites on Hyperlipidemia

Hyperlipidemia, defined as the presence of excess fat or lipids in the blood, has been considered as a high-risk factor and key indicator of many metabolic diseases. The gut microbiota has been reported playing a vital role in regulating host lipid metabolism. The pathogenic role of gut microbiota in the development of hyperlipidemia has been revealed through fecal microbiota transplantation experiment to germ-free mice. The effector mechanism of microbiota-related metabolites such as bile acids, lipopolysaccharide, and short-chain fatty acids in the regulation of hyperlipidemia has been partially unveiled. Moreover, studies on gut-microbiota-targeted hyperlipidemia interventions, including the use of prebiotics, probiotics, fecal microbiota transplantation, and natural herbal medicines, also have shown their efficacy in the treatment of hyperlipidemia. In this review, we summarize the relationship between gut microbiota and hyperlipidemia, the impact of gut microbiota and microbiota-related metabolites on the development and progression of hyperlipidemia, and the potential therapeutic management of hyperlipidemia targeted at gut microbiota.

Changes in serum total bile acid concentrations are associated with the risk of developing adverse maternal and perinatal outcomes in pregnant Chinese women

BACKGROUND AND AIMS

We aimed to investigate the association between total bile acid (TBA) concentrations changes during the second and third trimesters and the risk of developing adverse maternal and perinatal outcomes (AMPO).

METHODS

A total of 1569 pregnant Chinese women were enrolled. Serum TBA concentrations were measured during the 16-18^th and 29-34^th weeks of gestation. Logistic regression models were performed.

RESULTS

After multivariable adjustment, each standard deviation increase in the TBA concentrations in the second trimester was associated with a 30% (odds ratio [OR] = 1.30, 95% confidence interval [CI]: 1.13, 1.50) increased risk of gestational diabetes mellitus (GDM) and a 22% (OR = 1.22, 95% CI: 1.07, 1.63) increased risk of premature rupture of membranes (PROM). When we compared the highest and lowest quartiles of changes in the TBA Z-scores across the second and third trimesters, the adjusted ORs were 1.84 (95% CI: 1.28, 2.65) for PROM and 1.47 (95% CI: 1.07, 2.28) for macrosomia.

CONCLUSION

Elevated serum TBA concentrations during pregnancy were positively associated with increased risks of GDM and PROM. Women with more drastic changes in TBA concentrations across the second and third trimesters were at a higher risk of developing PROM and macrosomia.

Genetic variants associated with beta-cell function and insulin sensitivity potentially influence bile acid metabolites and gestational diabetes mellitus in a Chinese population

INTRODUCTION

To investigate associations between genetic variants related to beta-cell (BC) dysfunction or insulin resistance (IR) in type 2 diabetes (T2D) and bile acids (BAs), as well as the risk of gestational diabetes mellitus (GDM).

RESEARCH DESIGN AND METHODS

We organized a case-control study of 230 women with GDM and 217 without GDM nested in a large prospective cohort of 22 302 Chinese women in Tianjin, China. Two weighted genetic risk scores (GRSs), namely BC-GRS and IR-GRS, were established by combining 39 and 23 single nucleotide polymorphisms known to be associated with BC dysfunction and IR, respectively. Regression and mediation analyses were performed to evaluate the relationship of GRSs with BAs and GDM.

RESULTS

We found that the BC-GRS was inversely associated with taurodeoxycholic acid (TDCA) after adjustment for confounders (Beta (SE)=-0.177 (0.048); p=2.66×10^-4). The BC-GRS was also associated with the risk of GDM (OR (95% CI): 1.40 (1.10 to 1.77); p=0.005), but not mediated by TDCA. Compared with individuals in the low tertile of BC-GRS, the OR for GDM was 2.25 (95% CI 1.26 to 4.01) in the high tertile. An interaction effect of IR-GRS with taurochenodeoxycholic acid (TCDCA) on the risk of GDM was evidenced (p=0.005). Women with high IR-GRS and low concentration of TCDCA had a markedly higher OR of 14.39 (95% CI 1.59 to 130.16; p=0.018), compared with those with low IR-GRS and high TCDCA.

CONCLUSIONS

Genetic variants related to BC dysfunction and IR in T2D potentially influence BAs at early pregnancy and the development of GDM. The identification of both modifiable and non-modifiable risk factors may facilitate the identification of high-risk individuals to prevent GDM.

Lipid regulation of NLRP3 inflammasome activity through organelle stress

Inflammation driven by the NLRP3 inflammasome in macrophages is an important contributor to chronic metabolic diseases that affect growing numbers of individuals. Many of these diseases involve the pathologic accumulation of endogenous lipids or their oxidation products, which can activate NLRP3. Other endogenous lipids, however, can inhibit the activation of NLRP3. The intracellular mechanisms by which these lipids modulate NLRP3 activity are now being identified. This review discusses emerging evidence suggesting that organelle stress, particularly involving mitochondria, lysosomes, and the endoplasmic reticulum, may be key in lipid-induced modification of NLRP3 inflammasome activity.

Neurotensin differentially regulates bile acid metabolism and intestinal FXR-bile acid transporter axis in response to nutrient abundance

Studies demonstrate a role for neurotensin (NT) in obesity and related comorbidities. Bile acid (BA) homeostasis alterations are associated with obesity. We determined the effect of NT on BA metabolism in obese and non-obese conditions. Plasma and fecal BA profiles were analyzed by LC-MS/MS in male and female NT^+/+ and NT^-/- mice fed low-fat (LFD) or high-fat diet (HFD) for 6 weeks (early stage of obesity) or greater than 20 weeks (late stage of obesity). The nuclear farnesoid X receptor (FXR) and BA transporter mRNA expression were assessed in ileum, mouse enteroids, and human cell lines. HFD decreased plasma primary and secondary BAs in NT^+/+ mice; HFD-induced decrease of plasma BAs was improved in NT-deficient mice. In NT^+/+ mice, HFD inhibited ileal FXR and BA transporter expression; HFD-decreased expression of FXR and BA transporters was prevented in NT^-/- mice. Compared with LFD-fed NT^+/+ mice, LFD-fed NT^-/- mice had relatively lower levels of ileal FXR and BA transporter expression. Moreover, NT stimulates the expression of FXR and BA transporters in Caco-2 cells; however, stimulated expression of BA transporters was attenuated in NT^-/- enteroids. Therefore, we demonstrate that HFD disrupts the BA metabolism and ileal FXR and BA transporter axis which are improved in the absence of NT, suggesting that NT contributes to HFD-induced disruption of BA metabolism and plays an inhibitory role in the regulation of ileal FXR and BA transporter signaling under obese conditions. Conversely, NT positively regulates the expression of ileal FXR and BA transporters under non-obese conditions. Therefore, NT plays a dual role in obese and non-obese conditions, suggesting possible therapeutic strategies for obesity control.

Metabolomic signatures for liver tissue and cecum contents in high-fat diet-induced obese mice based on UHPLC-Q-TOF/MS

Background

The incidence of obesity is increasing worldwide, and it is a risk factor for diabetes, dyslipidemia, and nonalcoholic fatty liver disease. Our previous study had demonstrated that high-fat diet induced increased weight gain, fat weight, serum cholesterol, triglyceride, and ATL levels in liver, and influenced the diversity and composition of cecal microbiota in mice. Hence, this study aimed to investigate the roles of the gut microbially derived metabolites and liver metabolites between the obese and lean mice, focusing on their association with the progression of obesity induced by high-fat diet (HFD).

Methods

An obesity model in mice was established with HFD for 16 weeks. Cecal contents and liver tissues metabolomics based on ultraperformance liquid chromatography-quadrupole-time-of-flight mass spectrometry and orthogonal partial least squares discriminant analyses (OPLS-DA) was performed to identify the alterations in metabolites associated with obese mice.

Results

Obese and lean groups were clearly discriminated from each other on OPLS-DA score plot and major metabolites contributing to the discrimination were mainly involved in glycerophospholipid metabolism, primary bile acid biosynthesis, and biosynthesis of unsaturated fatty acids pathways. HFD-induced alterations of 19 metabolites in liver and 43 metabolites in cecum contents were identified as potential biomarkers related to obesity. Specifically, chenodeoxycholic acid, taurochenodeoxycholate, and tauroursodeoxycholic acid in liver were elevated 35.94, 24.36, and 18.71-fold, respectively. PI(P-16:0/18:1(9Z)), PG(19:0/16:0), PS(P-16:0/20:2(11Z,14Z)), PI(22:1(11Z)/12:0), and PE(21:0/0:0) in cecum were enhanced 884, 640.96, 226.63, 210.10, 45.13-fold in comparison with the lean mice. These metabolites were the most important biomarkers for discriminating between the obese and lean mice. In addition, cecum contents metabolites were strongly correlated with hepatic metabolites through gut-liver axis analysis.

Conclusions

HFD increased lipid profiles (i.e. glycerophospholipids, PC, PE, PI, PG, and PS) and total bile acid (primary and secondary bile acid) in liver and cecum, suggesting that they may play an important role in the progression of obesity. These metabolites can be used to better understand obesity and related disease induced by HFD. Furthermore, the level alterations of these metabolites can be used to assess the risk of obesity and the therapeutic effect of obesity management.

Multiplatform metabolomics for an integrative exploration of metabolic syndrome in older men

BACKGROUND

Metabolic syndrome (MetS), a cluster of factors associated with risks of developing cardiovascular diseases, is a public health concern because of its growing prevalence. Considering the combination of concomitant components, their development and severity, MetS phenotypes are largely heterogeneous, inducing disparity in diagnosis.

METHODS

A case/control study was designed within the NuAge longitudinal cohort on aging. From a 3-year follow-up of 123 stable individuals, we present a deep phenotyping approach based on a multiplatform metabolomics and lipidomics untargeted strategy to better characterize metabolic perturbations in MetS and define a comprehensive MetS signature stable over time in older men.

FINDINGS

We characterize significant changes associated with MetS, involving modulations of 476 metabolites and lipids, and representing 16% of the detected serum metabolome/lipidome. These results revealed a systemic alteration of metabolism, involving various metabolic pathways (urea cycle, amino-acid, sphingo- and glycerophospholipid, and sugar metabolisms…) not only intrinsically interrelated, but also reflecting environmental factors (nutrition, microbiota, physical activity…).

INTERPRETATION

These findings allowed identifying a comprehensive MetS signature, reduced to 26 metabolites for future translation into clinical applications for better diagnosing MetS.

FUNDING

The NuAge Study was supported by a research grant from the Canadian Institutes of Health Research (CIHR; MOP-62842). The actual NuAge Database and Biobank, containing data and biologic samples of 1,753 NuAge participants (from the initial 1,793 participants), are supported by the Fonds de recherche du Québec (FRQ; 2020-VICO-279753), the Quebec Network for Research on Aging, a thematic network funded by the Fonds de Recherche du Québec - Santé (FRQS) and by the Merck-Frost Chair funded by La Fondation de l'Université de Sherbrooke. All metabolomics and lipidomics analyses were funded and performed within the metaboHUB French infrastructure (ANR-INBS-0010). All authors had full access to the full data in the study and accept responsibility to submit for publication.

Development of an Efficient and Sensitive Chemical Derivatization-Based LC-MS/MS Method for Quantifying Gut Microbiota-Derived Metabolites in Human Plasma and Its Application in Studying Cardiovascular Disease

Recently, the gut microbiota has been found to be associated with many diseases, such as inflammatory bowel disease, depression, Parkinson's disease, cancer, metabolic syndrome, and cardiovascular disease (CVD). Among various gut microbiota-derived metabolites (GMs), short-chain fatty acids (SCFAs), bile acids (BAs), and tryptophan (TRP) metabolites are the most frequently discussed metabolites. LC-MS/MS shows advantages in quantifying the levels of metabolites with good sensitivity and selectivity; however, the poor ionization efficiency and polar characteristics of SCFAs make their analysis challenging, especially when analyzing plasma samples with low SCFA concentrations. Moreover, without characteristic fragment ions for unconjugated BAs and different detection ion modes for TRP metabolites and BAs, GM analysis is complex and time-consuming. To overcome these problems, we developed a derivatization method combined with LC-MS/MS to enhance the sensitivity and LC retention of GMs. Through derivatization with 3-nitrophenylhydrazine (3-NPH), 7 SCFAs, 9 bile acids, and 6 tryptophan metabolites can be simultaneously analyzed via separation within 14 min on a reversed-phase C18 column. For accurate quantification, ¹³C₆-3NPH-labeled standards were used as one-to-one internal standards. This derivatization approach was optimized and then validated. We further applied this method to investigate the targeted GM profile in patients with CVD. The results showed a significant reduction in plasma butyrate levels in CVD patients compared with healthy controls, suggesting its potentially protective role in CVD. In summary, this work provides a sensitive and effective LC-MS/MS method for simultaneously quantifying gut microbiota-related metabolites in human plasma, which could benefit various future gut microbiota-related studies.

Effects of Weight Loss and Moderate-Protein, High-Fiber Diet Consumption on the Fasted Serum Metabolome of Cats

Feline obesity elicits a plethora of metabolic responses leading to comorbidities, with potential reversal during weight loss. The specific metabolic alterations and biomarkers of organ dysfunction are not entirely understood. Untargeted, high-throughput metabolomic technologies may allow the identification of biological components that change with weight status in cats, increasing our understanding of feline metabolism. The objective of this study was to utilize untargeted metabolomic techniques to identify biomarkers and gain mechanistic insight into the serum metabolite changes associated with reduced food intake and weight loss in overweight cats. During a four-wk baseline period, cats were fed to maintain body weight. For 18 wk following baseline, cats were fed to lose weight at a rate of ~1.5% body weight/wk. Blood serum metabolites were measured at wk 0, 1, 2, 4, 8, 12, and 16. A total of 535 named metabolites were identified, with up to 269 of them being altered (p- and q-values < 0.05) at any time point. A principal component analysis showed a continual shift in metabolite profile as weight loss progressed, with early changes being distinct from those over the long term. The majority of lipid metabolites decreased with weight loss; however, ketone bodies and small lipid particles increased with weight loss. The majority of carbohydrate metabolites decreased with weight loss. Protein metabolites had a variable result, with some increasing, but others decreasing with weight loss. Metabolic mediators of inflammation, oxidative stress, xenobiotics, and insulin resistance decreased with weight loss. In conclusion, global metabolomics identified biomarkers of reduced food intake and weight loss in cats, including decreased markers of inflammation and/or altered macronutrient metabolism.

Evaluating causality of cellular senescence in non-alcoholic fatty liver disease

Cellular senescence is a state of irreversible cell cycle arrest that has important physiological functions. However, cellular senescence is also a hallmark of ageing and has been associated with several pathological conditions. A wide range of factors including genotoxic stress, mitogens and inflammatory cytokines can induce senescence. Phenotypically, senescent cells are characterised by short telomeres, an enlarged nuclear area and damaged genomic and mitochondrial DNA. Secretion of proinflammatory proteins, also known as the senescence-associated secretory phenotype, is a characteristic of senescent cells that is thought to be the main contributor to their disease-inducing properties. In the past decade, the role of cellular senescence in the development of non-alcoholic fatty liver disease (NAFLD) and its progression towards non-alcoholic steatohepatitis (NASH) has garnered significant interest. Until recently, it was suggested that hepatocyte cellular senescence is a mere consequence of the metabolic dysregulation and inflammatory phenomena in fatty liver disease. However, recent work in rodents has suggested that senescence may be a causal factor in NAFLD development. Although causality is yet to be established in humans, current evidence suggests that targeting senescent cells has therapeutic potential for NAFLD. We aim to provide insights into the quality of the evidence supporting a causal role of cellular senescence in the development of NAFLD in rodents and humans. We will elaborate on key cellular and molecular features of senescence and discuss the efficacy and safety of novel senolytic drugs for the treatment or prevention of NAFLD.

Exercise training and diet-induced weight loss increase markers of hepatic bile acid (BA) synthesis and reduce serum total BA concentrations in obese women

Regular exercise has profound metabolic influence on the liver, but effects on bile acid (BA) metabolism are less well known. BAs are synthesized exclusively in the liver from cholesterol via the rate-limiting enzyme cholesterol 7 alpha-hydroxylase (CYP7A1). BAs contribute to the solubilization and absorption of lipids and serve as important signaling molecules, capable of systemic endocrine function. Circulating BAs increase with obesity and insulin resistance, but effects following exercise and diet-induced weight loss are unknown. To test if improvements in fitness and weight loss as a result of exercise training enhance BA metabolism, we measured serum concentrations of total BAs (conjugated and unconjugated primary and secondary BAs) in sedentary, obese, insulin-resistant women (N = 11) before (PRE) and after (POST) a ∼14-wk exercise and diet-induced weight loss intervention. BAs were measured in serum collected after an overnight fast and during an oral glucose tolerance test (OGTT). Serum fibroblast growth factor 19 (FGF19; a regulator of BA synthesis) and 7-alpha-hydroxy-cholesten-3-one (C4, a marker of CYP7A1 enzymatic activity) also were measured. Using linear mixed-model analyses and the change in V̇O_2peak (mL/min/kg) as a covariate, we observed that exercise and weight loss intervention decreased total fasting serum BA by ∼30% (P = 0.001) and increased fasting serum C4 concentrations by 55% (P = 0.004). C4 was significantly correlated with serum total BAs only in the POST condition, whereas serum FGF19 was unchanged. These data indicate that a fitness and weight loss intervention modifies BA metabolism in obese women and suggest that improved metabolic health associates with higher postabsorptive (fasting) BA synthesis. Furthermore, pre- vs. postintervention patterns of serum C4 following an OGTT support the hypothesis that responsiveness of BA synthesis to postprandial inhibition is improved after exercise and weight loss.NEW & NOTEWORTHY Exercise and weight loss in previously sedentary, insulin-resistant women facilitates a significant improvement in insulin sensitivity and fitness that may be linked to changes in bile acid metabolism. Diet-induced weight loss plus exercise-induced increases in fitness promote greater postabsorptive bile acid synthesis while also sensitizing the bile acid metabolic system to feedback inhibition during a glucose challenge when glucose and insulin are elevated.

Gut Microbiota and Its Metabolite Deoxycholic Acid Contribute to Sucralose Consumption-Induced Nonalcoholic Fatty Liver Disease

As important signal metabolites within enterohepatic circulation, bile acids (BAs) play a pivotal role during the occurrence and development of diet-induced nonalcoholic fatty liver disease (NAFLD). Here, we evaluated the functional effects of BAs and gut microbiota contributing to sucralose consumption-induced NAFLD of mice. The results showed that sucralose consumption significantly upregulated the abundance of intestinal genera Bacteroides and Clostridium, which produced deoxycholic acid (DCA) accumulating in multiple biological matrixes including feces, serum, and liver of mice. Subsequently, elevated hepatic DCA, one of the endogenous antagonists of the farnesol X receptor (Fxr), inhibited hepatic gene expression including a small heterodimer partner (Shp) and Fxr leading to sucralose-induced NAFLD in mice. Dietary supplements with fructo-oligosaccharide or metformin markedly restored genera Bacteroides and Clostridium abundance and the DCA level of sucralose-consuming mice, which eventually ameliorated NAFLD. These findings highlighted the effects of gut microbiota and its metabolite DCA on sucralose-induced NAFLD of mice.

Role of Bile Acids in the Regulation of Food Intake, and Their Dysregulation in Metabolic Disease

Bile acids are cholesterol-derived metabolites with a well-established role in the digestion and absorption of dietary fat. More recently, the discovery of bile acids as natural ligands for the nuclear farnesoid X receptor (FXR) and membrane Takeda G-protein-coupled receptor 5 (TGR5), and the recognition of the effects of FXR and TGR5 signaling have led to a paradigm shift in knowledge regarding bile acid physiology and metabolic health. Bile acids are now recognized as signaling molecules that orchestrate blood glucose, lipid and energy metabolism. Changes in FXR and/or TGR5 signaling modulates the secretion of gastrointestinal hormones including glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), hepatic gluconeogenesis, glycogen synthesis, energy expenditure, and the composition of the gut microbiome. These effects may contribute to the metabolic benefits of bile acid sequestrants, metformin, and bariatric surgery. This review focuses on the role of bile acids in energy intake and body weight, particularly their effects on gastrointestinal hormone secretion, the changes in obesity and T2D, and their potential relevance to the management of metabolic disorders.

Bile acid metabolism and circadian rhythms

Circadian rhythms are biological systems that synchronize cellular circadian oscillators with the organism's daily feeding-fasting or rest-activity cycles in mammals. Circadian rhythms regulate nutrient absorption and utilization at the cellular level and are closely related to obesity and metabolic disorders. Bile acids are important modulators that facilitate nutrient absorption and regulate energy metabolism. Here, we provide an overview of the current connections and future perspectives between the circadian clock and bile acid metabolism as well as related metabolic diseases. Feeding and fasting cycles influence bile acid pool size and composition, and bile acid signaling can respond to acute lipid and glucose utilization and mediate energy balance. Disruption of circadian rhythms such as shift work, irregular diet, and gene mutations can contribute to altered bile acid metabolism and heighten obesity risk. High-fat diets, alcohol, and gene mutations related to bile acid signaling result in desynchronized circadian rhythms. Gut microbiome also plays a role in connecting circadian rhythms with bile acid metabolism. The underlying mechanism of how circadian rhythms interact with bile acid metabolism has not been fully explored. Sustaining bile acid homeostasis based on circadian rhythms may be a potential therapy to alleviate metabolic disturbance.

Hypoglycemic effects and mechanism of different molecular weights of konjac glucomannans in type 2 diabetic rats

Konjac glucomannan (KGM) is a hypoglycemic polysaccharide with a wide range of molecular weights. But study on hypoglycemic effects of KGMs relate to molecular weight is limited. In this study, KGMs with high and medium molecular weights, and the degraded KGMs were analyzed with physicochemical properties, hypoglycemic effects and mechanisms. Results showed that as the molecular weight KGMs decreased, the viscosity decreased, molecular flexibility increased, while chemical groups, crystal structures and main chains showed little change. KGMs with medium molecular weights (KGM-M1, KGM-M2) showed better effects on increasing body weight, decreasing levels of fasting blood glucose, insulin resistance, total cholesterol and low density lipoprotein cholesterol, and enhancing integrity of pancreas and colon, than KGMs with high or low molecular weights (KGM-H, KGM-L) in type 2 diabetic rats. Mechanism analysis suggested that KGM-M1 and KGM-M2 had higher antioxidant and anti-inflammatory activities on elevating superoxide dismutase, decreasing malondialdehyde and tumor necrosis factor-α levels. Moreover, KGM-M1 and KGM-M2 increased gut microbiota diversity, Bacteroidetes/Firmicutes ratio and Muribaculaceae, decreased Romboutsia and Klebsiella, and improved 6 diabetic related metabolites. Combined, KGM-M1 and KGM-M2 showed higher hypoglycemic effects, due to regulatory activities of antioxidant, anti-inflammatory, intestinal microbiota, and relieved metabolic disorders.

The role of gut microbiota (GM) and GM-related metabolites in diabetes and obesity. A review of analytical methods used to measure GM-related metabolites in fecal samples with a focus on metabolites' derivatization step

Disruption of gut microbiota (GM) composition is increasingly related to the pathogenesis of various metabolic diseases. Additionally, GM is responsible for the production and transformation of metabolites involved in the development of metabolic disorders, such as obesity and type 2 diabetes mellitus (T2DM). The current state of knowledge regarding the composition of GM and GM-related metabolites in relation to the progress and development of obesity and T2DM is presented in this review. To understand the relationships between GM-related metabolites and the development of metabolic disorders, their accurate qualitative and quantitative measurement in biological samples is needed. Feces represent a valuable biological matrix which composition may reflect the health status of the lower gastrointestinal tract and the whole organism. Mass spectrometry (MS), mainly in combination with gas chromatography (GC) or liquid chromatography (LC), is commonly used to measure fecal metabolites. However, profiling metabolites in such a complex matrix as feces is challenging from both analytical chemistry and biochemistry standpoints. Chemical derivatization is one of the most effective methods used to overcome these problems. In this review, we provide a comprehensive summary of the derivatization methods of GM-related metabolites prior to GC-MS or LC-MS analysis, which have been published in the last five years (2015-2020). Additionally, analytical methods used for the analysis of GM-related metabolites without the derivatization step are also presented.

Effects of laparoscopic sleeve gastrectomy on concentration and composition of bile acids in an Asian population with morbid obesity

Background:

Bile acids (BAs) are traditionally associated with lipid absorption and phase II detoxification by forming various BA conjugates. Recently, it has been discovered that BAs also regulate glucose metabolism, and the increase in BAs in patients following bariatric surgery may contribute to the post-surgery improvement in insulin resistance (IR). However, while Roux-en-Y gastric bypass can increase BA concentrations post-surgery, this may not be the case after laparoscopic sleeve gastrectomy (LSG). We hypothesized that the profiling of BAs that include the conjugated BA species could detect post-surgery BA changes after LSG. To test our hypothesis, we performed comprehensive profiling of BAs in Asian individuals with morbid obesity at baseline, and at 6 months following LSG.

Methods:

Fourteen subjects scheduled for LSG were recruited. Anthropometric measurements, oral glucose tolerance test, and biochemistry tests were performed at baseline and at 6 months after LSG. BAs were profiled using liquid chromatography–mass spectrometry.

Results:

At 6 months, subjects lost significant weight from 117.4±5.4 to 92.1±3.8 kg and demonstrated significant improvement in IR. HOMA-IR decreased from 6.2±0.7 to 2.0±0.2 and the Matsuda index increased from 1.9±0.3 to 3.3±0.3. We did not detect any significant post-operative change in the levels of total BAs (5237.1±1219.4 vs. 3631.7±457.9, p=0.181) or non-sulfated BAs after LSG. However, sulfated BA species increased significantly after LSG.

Conclusion:

Our study showed that the serum concentrations of sulfated BA species in morbidly obese Asian individuals increased significantly 6 months after LSG; the increase in sulfated BAs after LSG might contribute to the post-surgery improvement of metabolic health.

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.

Untargeted Profiling of Bile Acids and Lysophospholipids Identifies the Lipid Signature Associated with Glycemic Outcome in an Obese Non-Diabetic Clinical Cohort

The development of high throughput assays for assessing lipid metabolism in metabolic disorders, especially in diabetes research, nonalcoholic fatty liver disease (NAFLD), and nonalcoholic steatohepatitis (NASH), provides a reliable tool for identifying and characterizing potential biomarkers in human plasma for early diagnosis or prognosis of the disease and/or responses to a specific treatment. Predicting the outcome of weight loss or weight management programs is a challenging yet important aspect of such a program’s success. The characterization of potential biomarkers of metabolic disorders, such as lysophospholipids and bile acids, in large human clinical cohorts could provide a useful tool for successful predictions. In this study, we validated an LC-MS method combining the targeted and untargeted detection of these lipid species. Its potential for biomarker discovery was demonstrated in a well-characterized overweight/obese cohort subjected to a low-caloric diet intervention, followed by a weight maintenance phase. Relevant markers predicting successful responses to the low-caloric diet intervention for both weight loss and glycemic control improvements were identified. The response to a controlled weight loss intervention could be best predicted using the baseline concentration of three lysophospholipids (PC(22:4/0:0), PE(17:1/0:0), and PC(22:5/0:0)). Insulin resistance on the other hand could be best predicted using clinical parameters and levels of circulating lysophospholipids and bile acids. Our approach provides a robust tool not only for research purposes, but also for clinical practice, as well as designing new clinical interventions or assessing responses to specific treatment. Considering this, it presents a step toward personalized medicine.

Targeting bile acid metabolism in obesity reduction: A systematic review and meta-analysis

A systematic review and meta-analysis was conducted of studies that address the association of bile acid (BA) with obesity and of studies on the effects of treatment in patients with obesity on BA metabolism, assessed from systemic BA, fibroblast growth factor 19 (FGF19), 7α-hydroxy-4-cholesten-3-one (C4) level, and faecal BA. We searched PubMed, Embase, and the Cochrane Library from inception to 1 August 2019 using the keywords obesity, obese, body mass index, and overweight with bile acid, FGF19, FXR, and TGR5. Two reviewers independently searched, selected, and assessed the quality of studies. Data were analysed using either fixed or random effect models with inverse variance weighting. Of 3771 articles, 33 papers were relevant for the association of BA with obesity of which 22 were included in the meta-analysis, and 50 papers were relevant for the effect of obesity interventions on BA of which 20 were included in the meta-analysis. Circulating fasting total BA was not associated with obesity. FGF19 was inversely and faecal BA excretion was positively associated with obesity. Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) modulated BA metabolism, ie, increased BA and FGF19. Our results indicate that BA metabolism is altered in obesity. Certain bariatric surgeries including RYGB and SG modulate BA, whether these underlie the beneficial effect of the treatment should be investigated.

Serum Bile Acid Levels Before and After Sleeve Gastrectomy and Their Correlation with Obesity-Related Comorbidities

BACKGROUND AND AIMS

The rising prevalence of morbid obesity is increasing the demand for bariatric surgery. The benefits observed after bariatric surgery seems to be not fully explained by surgery-induced weight loss or traditional cardiovascular risk factors regression or improvement. Some evidences suggest that bile acid (BA) levels change after bariatric surgery, thus suggesting that BA concentrations could influence some of the metabolic improvement induced by bariatric surgery. In this report, we have characterized circulating BA patterns and compared them to metabolic and vascular parameters before and after sleeve gastrectomy (SG).

PATIENTS AND METHODS

Seventy-nine subjects (27 males, 52 females, aged 45 ± 12 years, mean BMI 45 ± 7 kg/m²) SG candidates were included in the study. Before and about 12 months after SG, all subjects underwent a clinical examination, blood tests (including lipid profile, plasma glucose and insulin, both used for calculating HOMA-IR, and glycated hemoglobin), ultrasound visceral fat area estimation, ultrasound flow-mediated dilation evaluation, and determination of plasma BA concentrations.

RESULTS

Before SG, both primary and secondary BA levels were higher in insulin-resistant obese subjects than in non-insulin resistant obese, and BA were positively associated with the markers of insulin-resistance. After SG, total (conjugated and unconjugated) cholic acids significantly decreased (p 0.007), and total lithocholic acids significantly increased (p 0.017). SG-induced total cholic and chenodeoxycholic acid changes were directly associated with surgery-induced glycemia (p 0.011 and 0.033 respectively) and HOMA-IR (p 0.016 and 0.012 respectively) changes.

CONCLUSIONS

Serum BA are associated with glucose metabolism and particularly with markers of insulin-resistance. SG modifies circulating BA pool size and composition. SG-induced BA changes are associated with insulin-resistance amelioration. In conclusion, an interplay between glucose metabolism and circulating BA exists but further studies are needed.

Fasting serum bile acids concentration is associated with insulin resistance independently of diabetes status

Background Bile acids (BAs) have been demonstrated to exert a variety of metabolic effects and alterations in BAs have been reported in patients with obesity, insulin resistance (IR) and type 2 diabetes mellitus (T2DM). However, it is unclear which metabolic condition is the main contributor to alterations in BAs. In this study, we investigate the associations between different BA profiles with glycemia, obesity or IR status. Methods Fasting serum concentrations of 15 BA species were determined in a total of 241 individuals (71 drug-naïve patients with T2DM, 95 patients with impaired fasting glucose [IFG], and 75 healthy controls. Results A comparison of the mean values of the BAs revealed no significant differences between normoglycemic controls and patients with IFG or T2DM. However, when the entire cohort was divided according to the presence of IR as determined by a homeostasis model assessment of insulin resistance (HOMA-IR) value >2.5, the levels of total BA and most species of BAs were significantly higher in patients with IR than in patients without. In the correlation analysis, most species of BAs, as well as total BA, were significantly associated with HOMA-IR levels. Furthermore, when the subjects were divided into four groups according to IR and diabetic status, subjects with IR had significantly higher total BAs than participants without IR both in diabetic and non-diabetic groups. Ultimately, multiple linear regression analysis identified HOMA-IR as the only significant contributor to most serum BA species. Conclusions Our findings support the essential role of IR in regulating BA metabolism and that this effect is independent of diabetic status.

Bile Acid Changes Associated With Liver Fibrosis and Steatosis in the Mexican-American Population of South Texas

Biomarkers to predict risk of liver fibrosis in subjects with nonalcoholic fatty liver disease, a common risk factor for hepatocellular carcinoma, would allow for early preventive interventions. We sought to characterize bile acid profiles associated with liver fibrosis in subjects from the community‐based Cameron County Hispanic Cohort, a population in South Texas with high rates of nonalcoholic fatty liver disease, liver fibrosis and hepatocellular carcinoma. Plasma bile acid levels were measured in 390 subjects. These subjects were screened with liver elastography, detecting significant liver fibrosis in 58 subjects and steatosis in 186 subjects. Unsupervised clustering of the bile acid profiles revealed five clusters that differed by liver fibrosis, liver steatosis, liver injury, age and gender, identifying these parameters as major determinants of circulating bile acid changes. Total bile acid levels were significantly higher in subjects with fibrosis, with chenodeoxycholic acid displaying the greatest increase among individual bile acids. The primary conjugated bile acids, glycocholic and glycochenodeoxycholic acids, displayed the strongest association with fibrosis by logistic regression. High lithocholic acid levels were strongly associated with advanced fibrosis. In contrast, deoxycholic acid and total unconjugated secondary bile acids were positively associated with steatosis, whereas relative glycoursodeoxycholic acid abundance was negatively associated. Milk and yogurt intake notably contributed to fibrosis‐associated bile acid changes. In addition, multiple families within the Firmicutes phylum, Prevotellaceae, and Bacteroides species in stool significantly correlated with fibrosis‐associated and steatosis‐associated bile acid parameters, suggesting that the gut microbiome contributes to bile acid changes in the context of liver disease. Conclusion: Circulating bile acid levels were markedly but differently changed in liver fibrosis and steatosis in a high‐risk Mexican‐American population.

Adipose Tissue Distribution, Inflammation and Its Metabolic Consequences, Including Diabetes and Cardiovascular Disease

Adipose tissue plays essential roles in maintaining lipid and glucose homeostasis. To date several types of adipose tissue have been identified, namely white, brown, and beige, that reside in various specific anatomical locations throughout the body. The cellular composition, secretome, and location of these adipose depots define their function in health and metabolic disease. In obesity, adipose tissue becomes dysfunctional, promoting a pro-inflammatory, hyperlipidemic and insulin resistant environment that contributes to type 2 diabetes mellitus (T2DM). Concurrently, similar features that result from adipose tissue dysfunction also promote cardiovascular disease (CVD) by mechanisms that can be augmented by T2DM. The mechanisms by which dysfunctional adipose tissue simultaneously promote T2DM and CVD, focusing on adipose tissue depot-specific adipokines, inflammatory profiles, and metabolism, will be the focus of this review. The impact that various T2DM and CVD treatment strategies have on adipose tissue function and body weight also will be discussed.