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Background: The importance of the gut microbiome for bone metabolism in mice has recently been demonstrated, but no studies are available in humans. Lactobacillus reuteri ATCCPTA 6475 (L. reuteri 6475) has been reported to increase bone mineral density (BMD) in mice but its effect on the human skeleton is unknown. The objective of this trial was to investigate if L. reuteri 6475 affects bone loss in older women with low BMD.Methods: In this double-blind, placebo-controlled study, women from the population who were 75 to 80 years old and had low BMD were randomized to orally receive 1010 colony-forming units of L. reuteri 6475 daily or placebo. The predefined primary end-point was relative change after 12 months in tibia total volumetric BMD (vBMD).Results: Ninety women were included and 70 completed the study. L. reuteri 6475 reduced loss of total vBMD compared to placebo both in the intention-to-treat (ITT) analysis [-0.83% (95% confidence interval [CI], -1.47 to -0.19%) vs. -1.85% (95% CI, -2.64 to -1.07%); mean difference 1.02% (95% CI, 0.02-2.03)] and per protocol analysis [-0.93% (95% CI, -1.45 to -0.40) vs. -1.86% (95% CI, -2.35 to -1.36); mean difference 0.93% (95% CI, 0.21-1.65)]. In general, similar but smaller effects were observed in the secondary bone variable outcomes, but these differences did not reach statistical significance in the ITT population. Adverse events did not differ between groups.Conclusions: Supplementation with L. reuteri 6475 should be further explored as a novel approach to prevent age-associated bone loss and osteoporosis. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: Post-bariatric hypoglycemia (PBH) is caused by postprandial hyperinsulinemia, due to anatomical alterations and changes in post-prandial metabolism after bariatric surgery. The mechanisms underlying the failing regulatory and compensatory systems are unclear. In this study, we investigated the differences in post-prandial hormones and metabolic profiles between patients with and without PBH., Methods: We performed a mixed meal test (MMT) in 63 subjects before and 1 year after Roux-en-Y gastric bypass (RYGB) surgery. Blood was withdrawn at 0, 10, 20, 30, 60, and 120 min after ingestion of a standardized meal. Glucose, insulin, GLP-1, FGF-19, and FGF-21 were measured and untargeted metabolomics analysis was performed on blood plasma to analyze which hormonal and metabolic systems were altered between patients with and without PBH., Results: Out of 63, a total of 21 subjects (33%) subjects developed PBH (glucose < 3.1 mmol/L) after surgery. Decreased glucose and increased insulin excursions during MMT were seen in PBH (p < 0.05). GLP-1, FGF-19, and FGF-21 were elevated after surgery (p < 0.001), but did not differ between PBH and non-PBH groups. We identified 20 metabolites possibly involved in carbohydrate metabolism which differed between the two groups, including increased carnitine and acylcholines in PBH., Conclusion: Overall, 33% of the subjects developed PBH 1 year after RYGB surgery. While GLP-1, FGF-19, and FGF-21 were similar in PBH and non-PBH patients, metabolomics analysis revealed changes in carnitine and acyclcholines that are possibly involved in energy metabolism, which may play a role in the occurrence of PBH., (© 2024. The Author(s).)

Steatotic liver disease has been shown to associate with cardiovascular disease independently of other risk factors. Lipoproteins have been shown to mediate some of this relationship but there remains unexplained variance. Here we investigate the plasma lipidomic changes associated with liver steatosis and the mediating effect of these lipids on coronary artery disease (CAD). In a population of 2579 Swedish participants of ages 50 to 65 years, lipids were measured by mass spectrometry, liver fat was measured using computed tomography (CT), and CAD status was defined as the presence of coronary artery calcification (CAC score > 0). Lipids associated with liver steatosis and CAD were identified and their mediating effects between the two conditions were investigated. Out of 458 lipids, 284 were found to associate with liver steatosis and 19 of them were found to also associate with CAD. Two fatty acids, docosatrienoate (22:3n6) and 2-hydroxyarachidate, presented the highest mediating effect between steatotic liver disease and CAD. Other mediators were also identified among sphingolipids and glycerophospholipids, although their mediating effects were attenuated when adjusting for circulating lipoproteins. Further research should investigate the role of docosatrienoate (22:3n6) and 2-hydroxyarachidate as mediators between steatotic liver disease and CAD alongside known risk factors., (© 2024. The Author(s).)

Background: Growing evidence indicates that trimethylamine N -oxide, a gut microbial metabolite of dietary choline and carnitine, promotes both cardiovascular disease and chronic kidney disease risk. It remains unclear how circulating concentrations of trimethylamine N -oxide and its related dietary and gut microbe-derived metabolites (choline, betaine, carnitine, γ-butyrobetaine, and crotonobetaine) affect incident heart failure (HF)., Methods: We evaluated 11 768 participants from the Cardiovascular Health Study and the Multi-Ethnic Study of Atherosclerosis with serial measures of metabolites. Cox proportional hazard models were used to examine the associations between metabolites and incident HF, adjusted for cardiovascular disease risk factors., Results: In all, 2102 cases of HF occurred over a median follow-up of 15.9 years. After adjusting for traditional risk factors, higher concentrations of trimethylamine N -oxide (hazard ratio, 1.15 [95% CI, 1.09-1.20]; P <0.001), choline (hazard ratio, 1.44 [95% CI, 1.26-1.64]; P <0.001), and crotonobetaine (hazard ratio, 1.24 [95% CI, 1.16-1.32]; P <0.001) were associated with increased risk for incident HF. After further adjustment for renal function (potential confounder or mediator), these associations did not reach Bonferroni-corrected statistical significance ( P =0.01, 0.049, and 0.006, respectively). Betaine and carnitine were nominally associated with a higher incidence of HF ( P <0.05). In exploratory analyses, results were similar for subtypes of HF based on left ventricular ejection fraction, and associations appeared generally stronger among Black and Hispanic/Latino versus White adults, although there were no interactions for any metabolites with race., Conclusions: In this pooled analysis of 2 well-phenotyped, diverse, community-based cohorts, circulating concentrations of gut microbe-derived metabolites such as trimethylamine N -oxide, choline, and crotonobetaine were independently associated with a higher risk of developing HF., Registration: URL: https://www.clinicaltrials.gov/; Unique identifiers: NCT00005133 and NCT00005487., Competing Interests: Dr Tang is a consultant for Sequana Medical, Cardiol Therapeutics, Genomics plc, Zehna Therapeutics, WhiteSwell, Boston Scientific, CardiaTec Biosciences, Intellia Therapeutics, Bristol Myers Squibb, Alleviant Medical, Alexion Pharmaceuticals, BioCardia, and Salubris Biotherapeutics and has received honorarium from Springer Nature, Belvoir Media Group, and American Board of Internal Medicine. Drs Hazen and Z. Wang report being named as co-inventors on pending and issued patents held by the Cleveland Clinic relating to cardiovascular diagnostics and therapeutics. Drs Hazen and Z. Wang report having received royalty payments for inventions or discoveries related to cardiovascular diagnostics or therapeutics from Cleveland Heart Lab, a fully owned subsidiary of Quest Diagnostics, and Procter & Gamble. Dr Hazen is a paid consultant for Zehna Therapeutics and Proctor & Gamble and has received research funds from Zehna Therapeutics, Proctor & Gamble, Pfizer Inc, and Roche Diagnostics. Dr Bäckhed reports receiving research support from Biogaia AB, is founder and shareholder of Implexion Pharma AB and Roxbiosens Inc, and is on the scientific advisory board for Bactolife A/S. Dr Psaty reported serving on the Steering Committee of the Yale Open Data Access Project funded by Johnson & Johnson. Dr Mozaffarian reported receiving personal fees from Acasti Pharma Inc, America’s Test Kitchen, Barilla, Cleveland Clinic Foundation, Danone SA, GOED (Global Organization for EPA and DHA Omega-3s), and Motif FoodWorks; serving on the scientific advisory board for Beren Therapeutics GmbH, Brightseed, Calibrate, DayTwo (ended June 2020), Elysium Health, Filtricine Inc, Foodome, HumanCo, January Inc, Perfect Day Inc, Season, and Tiny Organics; and receiving chapter royalties from UpToDate outside the submitted work. The other authors report no conflicts.

Background: An altered gut microbiome characterized by reduced abundance of butyrate producing bacteria and reduced gene richness is associated with type 2 diabetes (T2D). An important complication of T2D is increased risk of cognitive impairment and dementia. The biguanide metformin is a commonly prescribed medication for the control of T2D and metformin treatment has been associated with a significant reduction in the risk of dementia and improved cognition, particularly in people with T2D., Aim: To investigate the associations of metformin use with cognition exploring potential mechanisms by analyzing the gut microbiome and plasma metabolome using shotgun metagenomics and HPLC-ESI-MS/MS, respectively., Methods: We explored two independent cohorts: an observational study (Aging Imageomics) and a phase IV, randomized, double-blind, parallel-group, randomized pilot study (MEIFLO). From the two studies, we analyzed four study groups: (1) individuals with no documented medical history or medical treatment (n = 172); (2) people with long-term T2D on metformin monotherapy (n = 134); (3) people with long-term T2D treated with oral hypoglycemic agents other than metformin (n = 45); (4) a newly diagnosed T2D subjects on metformin monotherapy (n = 22). Analyses were also performed stratifying by sex., Results: Several bacterial species belonging to the Proteobacteria (Escherichia coli) and Verrucomicrobia (Akkermansia muciniphila) phyla were positively associated with metformin treatment, while bacterial species belonging to the Firmicutes phylum (Romboutsia timonensis, Romboutsia ilealis) were negatively associated. Due to the consistent increase in A. muciniphila and decrease in R.ilealis in people with T2D subjects treated with metformin, we investigated the association between this ratio and cognition. In the entire cohort of metformin-treated T2D subjects, the A.muciniphila/R.ilealis ratio was not significantly associated with cognitive test scores. However, after stratifying by sex, the A.muciniphila/R. ilealis ratio was significantly and positively associated with higher memory scores and improved memory in men. Metformin treatment was associated with an enrichment of microbial pathways involved in the TCA cycle, and butanoate, arginine, and proline metabolism in both cohorts. The bacterial genes involved in arginine metabolism, especially in production of glutamate (astA, astB, astC, astD, astE, putA), were enriched following metformin intake. In agreement, in the metabolomics analysis, metformin treatment was strongly associated with the amino acid proline, a metabolite involved in the metabolism of glutamate., Conclusions: The beneficial effects of metformin may be mediated by changes in the composition of the gut microbiota and microbial-host-derived co-metabolites., Competing Interests: Declaration of competing interest F.B. receives research support from Biogaia AB, is founder and shareholder of Implexion Pharma AB, Roxbiosens Inc., and on the scientific advisory board for Bactolife A/S. The other authors declare that they have no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Bariatric surgery is an effective treatment option for obesity and provides long-term weight loss and positive effects on metabolism, but the underlying mechanisms are poorly understood. Alterations in bile acid metabolism have been suggested as a potential contributing factor, but comprehensive studies in humans are lacking., Methods: In this study, we analysed the postprandial responses of bile acids, C4 and FGF19 in plasma, and excretion of bile acids in faeces, before and after bariatric surgery in patients (n = 38; 74% females) with obesity with or without type 2 diabetes from the BARIA cohort., Findings: We observed that total fasting plasma bile acid levels increased, and faecal excretion of bile acids decreased after surgery suggesting increased reabsorption of bile acids. Consistent with increased bile acid levels after surgery we observed increased postprandial levels of FGF19 and suppression of the bile acid synthesis marker C4, suggesting increased FXR activation in the gut. We also noted that a subset of bile acids had altered postprandial responses before and after surgery. Finally, fasting plasma levels of 6α-hydroxylated bile acids, which are TGR5 agonists and associated with improved glucose metabolism, were increased after surgery and one of them, HDCA, covaried with diabetes remission in an independent cohort., Interpretation: Our findings provide new insights regarding bile acid kinetics and suggest that bariatric surgery in humans alters bile acid profiles leading to activation of FXR and TGR5, which may contribute to weight loss, improvements in glucose metabolism, and diabetes remission., Funding: Novo Nordisk Fonden, Leducq Foundation, Swedish Heart-Lung Foundation, Knut and Alice Wallenberg Foundation, the ALF-agreement, ZonMw., Competing Interests: Declaration of interests F.B. receives research funding from Biogaia AB, is co-founder and shareholder of Roxbiosens Inc and Implexion AB, and is on the scientific advisory board of Bactolife A/S. L.O is co-founder and shareholder of Roxbiosens Inc. V.G. receives research funding from Spaarne Gastuis. M.N is member of the Scientific Advisory Board of and holds equity in Caelus Pharmaceuticals and receives research funding from and holds equity in Ami therapeutics, the Netherlands. However, none of these possible conflicts of interest bear direct relations to the content of the current paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background and Aims: Bile acids (BA) are vital regulators of metabolism. BAs are AQ6 secreted in the small intestine, reabsorbed, and transported back to the liver, where they can modulate metabolic functions. There is a paucity of data regarding the portal BA composition in humans. This study aimed to address this knowledge gap by investigating portal BA composition and the relation with peripheral and fecal BA dynamics in conjunction with the gut microbiome., Approach and Results: Thirty-three individuals from the BARIA cohort were included. Portal plasma, peripheral plasma, and feces were collected. BA and C4 levels were measured employing mass spectrometry. FGF19 was measured using ELISA. Gut microbiota composition was determined through metagenomics analysis on stool samples. Considerable diversity in the portal BA composition was observed. The majority (n = 26) of individuals had a 9-fold higher portal than peripheral BA concentration. In contrast, 8 individuals showed lower portal BA concentration compared with peripheral and had higher levels of unconjugated and secondary BA in this compartment, suggesting more distal origin. The altered portal BA profile was associated with altered gut microbiota composition. In particular, taxa within Bacteroides were reduced in abundance in the feces of these individuals., Conclusions: Characterization of the portal BA composition in relation to peripheral and fecal BA increased insight into the dynamics of BA metabolism in individuals with obesity. Peripheral BA composition was much more diverse due to microbial metabolism. About 24% of the portal samples was surprisingly low in total BA; the underlying mechanism requires further exploration., (Copyright © 2024 American Association for the Study of Liver Diseases.)

Alterations in gut microbiota composition are suggested to contribute to cardiometabolic diseases, in part by producing bioactive molecules. Some of the metabolites are produced by very low abundant bacterial taxa, which largely have been neglected due to limits of detection. However, the concentration of microbially produced metabolites from these taxa can still reach high levels and have substantial impact on host physiology. To explore this concept, we focused on the generation of secondary bile acids by 7α-dehydroxylating bacteria and demonstrated that addition of a very low abundant bacteria to a community can change the metabolic output dramatically. We show that Clostridium scindens converts cholic acid into the secondary bile acid deoxycholic acid (DCA) very efficiently even though the abundance of C. scindens is low, but still detectable by digital droplet PCR. We also show that colonization of germ-free female mice with a community containing C. scindens induces DCA production and affects host metabolism. Finally, we show that DCA correlates with impaired glucose metabolism and a worsened lipid profile in individuals with type 2 diabetes, which implies that this metabolic pathway may contribute to the development of cardiometabolic disease., (© 2024. The Author(s).)

Objectives: Gut microbiota increases energy availability through fermentation of dietary fibers to short-chain fatty acids in conventionally raised mice. Energy deficiency in germ-free (GF) mice increases glucagon-like peptide-1 (GLP-1) levels, which slows intestinal transit. To further analyze the role of GLP-1-mediated signaling in this model of energy deficiency, we re-derived mice lacking GLP-1 receptor (GLP-1R KO) as GF., Methods: GLP-1R KO mice were rederived as GF through hysterectomy and monitored for 30 weeks. Mice were subjected to rescue experiments either through feeding an energy-rich diet or colonization with a normal cecal microbiota. Histology and intestinal function were assessed at different ages. Intestinal organoids were assessed to investigate stemness., Results: Unexpectedly, 25% of GF GLP-1R KO mice died before 20 weeks of age, associated with enlarged ceca, increased cecal water content, increased colonic expression of apical ion transporters, reduced number of goblet cells and loss of colonic epithelial integrity. Colonocytes from GLP-1R KO mice were energy-deprived and exhibited increased ER-stress; mitochondrial fragmentation, increased oxygen levels and loss of stemness. Restoring colonic energy levels either by feeding a Western-style diet or colonization with a normal gut microbiota normalized gut phenotypes and prevented lethality., Conclusions: Our findings reveal a heretofore unrecognized role for GLP-1R signaling in the maintenance of colonic physiology and survival during energy deprivation., Competing Interests: Declaration of competing interest F.B. receives research support from Biogaia AB, is founder and shareholder of Implexion Pharma AB, Roxbiosens Inc, and on the scientific advisory board for Bactolife A/S. D.J.D. has served as a consultant or speaker within the past 12 months to Altimmune, Amgen, Kallyope, Merck Research Laboratories, Novo Nordisk Inc., Pfizer Inc. and Sanofi Inc.. Neither D.J.D. nor his family members hold issued stock directly or indirectly in any of these companies. D.J.D holds non-exercised options in Kallyope., (Copyright © 2024 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Background and Aims: Recent developments in high-throughput proteomic technologies enable the discovery of novel biomarkers of coronary atherosclerosis. The aims of this study were to test if plasma protein subsets could detect coronary artery calcifications (CAC) in asymptomatic individuals and if they add predictive value beyond traditional risk factors., Methods: Using proximity extension assays, 1,342 plasma proteins were measured in 1,827 individuals from the Impaired Glucose Tolerance and Microbiota (IGTM) study and 883 individuals from the Swedish Cardiopulmonary BioImage Study (SCAPIS) aged 50-64 years without history of ischaemic heart disease and with CAC assessed by computed tomography. After data-driven feature selection, extreme gradient boosting machine learning models were trained on the IGTM cohort to predict the presence of CAC using combinations of proteins and traditional risk factors. The trained models were validated in SCAPIS., Results: The best plasma protein subset (44 proteins) predicted CAC with an area under the curve (AUC) of 0.691 in the validation cohort. However, this was not better than prediction by traditional risk factors alone (AUC = 0.710, P = .17). Adding proteins to traditional risk factors did not improve the predictions (AUC = 0.705, P = .6). Most of these 44 proteins were highly correlated with traditional risk factors., Conclusions: A plasma protein subset that could predict the presence of subclinical CAC was identified but it did not outperform nor improve a model based on traditional risk factors. Thus, support for this targeted proteomics platform to predict subclinical CAC beyond traditional risk factors was not found., Competing Interests: Conflict of interest None., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)