| 1. |
- De Vadder, Filipe, et al.
(author)
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Gut microbiota regulates maturation of the adult enteric nervous system via enteric serotonin networks
- 2018
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 115:25, s. 6458-6463
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Journal article (peer-reviewed)abstract
- The enteric nervous system (ENS) is crucial for essential gastrointestinal physiologic functions such as motility, fluid secretion, and blood flow. The gut is colonized by trillions of bacteria that regulate host production of several signaling molecules including serotonin (5-HT) and other hormones and neurotransmitters. Approximately 90% of 5-HT originates from the intestine, and activation of the 5-HT4 receptor in the ENS has been linked to adult neurogenesis and neuroprotection. Here, we tested the hypothesis that the gut micro-biota could induce maturation of the adult ENS through release of 5-HT and activation of 5-HT4 receptors. Colonization of germ-free mice with a microbiota from conventionally raised mice modified the neuroanatomy of the ENS and increased intestinal transit rates, which was associated with neuronal and mucosal 5-HT production and the proliferation of enteric neuronal progenitors in the adult intestine. Pharmacological modulation of the 5-HT4 receptor, as well as depletion of endogenous 5-HT, identified a mechanistic link between the gut microbiota and maturation of the adult ENS through the release of 5-HT and activation of the 5-HT4 receptor. Taken together, these findings show that the microbiota modulates the anatomy of the adult ENS in a 5-HT-dependent fashion with concomitant changes in intestinal transit.
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| 2. |
- Heiss, Christina, et al.
(author)
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The gut microbiota regulates hypothalamic inflammation and leptin sensitivity in Western diet-fed mice via a GLP-1R-dependent mechanism
- 2021
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In: Cell Reports. - : Elsevier BV. - 2211-1247. ; 35:8
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Journal article (peer-reviewed)abstract
- Mice lacking a microbiota are protected from diet-induced obesity. Previous studies have shown that feeding a Western diet causes hypothalamic inflammation, which in turn can lead to leptin resistance and weight gain. Here, we show that wild-type (WT) mice with depleted gut microbiota, i.e., germ-free (GF) and antibiotic-treated mice, have elevated levels of glucagon-like peptide-1 (GLP-1), are protected against diet-induced hypothalamic inflammation, and have enhanced leptin sensitivity when fed a Western diet. Using GLP-1 receptor (GLP-1R)-deficient mice and pharmacological inhibition of the GLP-1R in WT mice, we demonstrate that intact GLP-1R signaling is required for preventing hypothalamic inflammation and enhancing leptin sensitivity. Furthermore, we show that astrocytes express the GLP-1R, and deletion of the receptor in glial fibrillary acidic protein (GFAP)-expressing cells diminished the antibiotic-induced protection against diet-induced hypothalamic inflammation. Collectively, our results suggest that depletion of the gut microbiota attenuates diet-induced hypothalamic inflammation and enhances leptin sensitivity via GLP-1R-dependent mechanisms.
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| 3. |
- Koh, Ara, et al.
(author)
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Microbially Produced Imidazole Propionate Impairs Insulin Signaling through mTORC1
- 2018
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In: Cell. - : Elsevier BV. - 0092-8674. ; 175:4
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Journal article (peer-reviewed)abstract
- Interactions between the gut microbiota, diet, and the host potentially contribute to the development of metabolic diseases. Here, we identify imidazole propionate as a microbially produced histidine-derived metabolite that is present at higher concentrations in subjects with versus without type 2 diabetes. We show that imidazole propionate is produced from histidine in a gut simulator at higher concentrations when using fecal microbiota from subjects with versus without type 2 diabetes and that it impairs glucose tolerance when administered to mice. We further show that imidazole propionate impairs insulin signaling at the level of insulin receptor substrate through the activation of p38 gamma MAPK, which promotes p62 phosphorylation and, subsequently, activation of mechanistic target of rapamycin complex 1 (mTORC1). We also demonstrate increased activation of p62 and mTORC1 in liver from subjects with type 2 diabetes. Our findings indicate that the microbial metabolite imidazole propionate may contribute to the pathogenesis of type 2 diabetes.
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| 4. |
- Mannerås Holm, Louise, 1980, et al.
(author)
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Adipose tissue has aberrant morphology and function in PCOS: enlarged adipocytes and low serum adiponectin, but not circulating sex steroids, are strongly associated with insulin resistance.
- 2011
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In: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 96:2
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Journal article (peer-reviewed)abstract
- Context: Comprehensive characterization of the adipose tissue in women with polycystic ovary syndrome (PCOS), over a wide range of body mass indices (BMIs), is lacking. Mechanisms behind insulin resistance in PCOS are unclear. Objective: To characterize the adipose tissue of women with PCOS and controls matched pair-wise for age and BMI, and to identify factors, among adipose tissue characteristics and serum sex steroids, that are associated with insulin sensitivity in PCOS. Design/Outcome Measures: Seventy-four PCOS women and 31 controls were included. BMI was 18-47 (PCOS) and 19-41 kg/m2 (controls). Anthropometric variables, volumes of subcutaneous/visceral adipose tissue (magnetic resonance imaging; MRI), and insulin sensitivity (clamp) were investigated. Adipose tissue biopsies were obtained to determine adipocyte size, lipoprotein lipase (LPL) activity, and macrophage density. Circulating testosterone, free testosterone, free 17β-estradiol, SHBG, glycerol, adiponectin, and serum amyloid A were measured/calculated. Results: Comparison of 31 pairs revealed lower insulin sensitivity, hyperandrogenemia, and higher free 17β-estradiol in PCOS. Abdominal adipose tissue volumes/distribution did not differ in the groups, but PCOS women had higher waist-to-hip ratio, enlarged adipocytes, reduced adiponectin, and lower LPL activity. In regression analysis, adipocyte size, adiponectin, and waist circumference were the factors most strongly associated with insulin sensitivity in PCOS (R2=0.681, P < 0.001). Conclusions: In PCOS, adipose tissue has aberrant morphology/function. Increased waist-to-hip ratio indicates abdominal/visceral fat accumulation, but this is not supported by MRI. Enlarged adipocytes and reduced serum adiponectin, together with a large waistline, rather than androgen excess, may be central factors in the pathogenesis/maintenance of insulin resistance in PCOS.
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| 5. |
- Mannerås Holm, Louise, 1980, et al.
(author)
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Coagulation and Fibrinolytic Disturbances in Women with Polycystic Ovary Syndrome.
- 2011
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In: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 96:4, s. 1068-76
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Journal article (peer-reviewed)abstract
- Context: Studies of fibrinolysis/coagulation status in women with polycystic ovary syndrome (PCOS) are contradictory. Objectives: The aim of the study was to investigate whether women with PCOS have disturbed circulating levels of fibrinolysis/coagulation markers and, if so, whether the disturbances are related to hemodynamics, metabolic variables, sex steroids, SHBG, lipids, and inflammatory variables in women with PCOS. Design/Main Outcome Measures: Anthropometric variables, hemodynamics, circulating hemostatic and inflammatory markers, and serum lipid profile were measured in women with untreated PCOS (n = 74) and controls (n = 31). Results: After adjustments for age and body mass index (BMI), circulating plasminogen activator inhibitor 1 (PAI-1) activity and fibrinogen levels were higher in women with PCOS than controls; lipid profile, blood pressure, and levels of D-dimer, von Willebrand factor, factor VIII, tissue plasminogen activator, and inflammatory markers were comparable in the two groups. In multiple linear regression analyses including women with PCOS, low SHBG and high insulin predicted high PAI-1 activity (R(2) = 0.526; P < 0.001); elevated high-sensitivity C-reactive protein and soluble E-selectin in combination with heart rate predicted high fibrinogen (R(2) = 0.333; P < 0.001). Differences in PAI-1 activity were not significant after adjustments for age, BMI, SHBG, and insulin. Conclusions: PCOS is characterized by a prothrombotic state, as reflected by increased PAI-1 activity and fibrinogen, without signs of dyslipidemia or a proinflammatory state. Low SHBG and high insulin may partly explain the BMI-independent difference in PAI-1 activity between women with PCOS and controls. High-sensitivity C-reactive protein and E-selectin may be involved in regulating fibrinogen in PCOS.
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| 6. |
- Stener-Victorin, Elisabet, 1964, et al.
(author)
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Effects of acupuncture and exercise on insulin sensitivity, adipose tissue characteristics, and markers of coagulation and fibrinolysis in women with polycystic ovary syndrome: secondary analyses of a randomized controlled trial.
- 2012
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In: Fertility and Sterility. - : Elsevier BV. - 0015-0282 .- 1556-5653. ; 97:2, s. 501-508
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Journal article (peer-reviewed)abstract
- Objective: To investigate the possible effects of low-frequency electro-acupuncture (EA) and physical exercise on markers of coagulation and fibrinolysis, insulin sensitivity, and adipose tissue characteristics in women with PCOS. Design: Secondary analyses of a prospective, randomized controlled clinical trial. ClinicalTrials.gov (identifier NCT00484705) Settings: Department of Physiology and Department of Obstetrics and Gynecology, Universtiy of Gothenburg. Patients/Interventions: Eighty-four women with PCOS were randomized to sixteen weeks of low-frequency EA (14 treatments), physical exercise (at least 3 times/week) or no intervention. Main outcome measures: Anthropometrics, circulating coagulation and fibrinolytic markers, insulin sensitivity (euglycemic hyperinsulinemic clamp), hemodynamics, and adipose tissue morphology/function recorded at baseline, after 16 weeks of intervention, and after a 16 week follow-up. Results: In the low-frequency EA group, circulating plasminogen activator inhibitor (PAI-1) activity decreased by 21.8% after 16 weeks of intervention and by 31.1% at the 16 week follow-up and differed from the physical exercise and the no-intervention groups. The EA group had decreases in circulating fibrinogen and t-PA, sagittal diameter, and diastolic blood pressure after treatment, and fibrinogen remained lower at the 16-week follow-up. In the physical exercise group, lipoprotein lipase activity increased and diastolic blood pressure decreased after treatment, and both diastolic and systolic blood pressure were lower at follow-up. No other variables were affected. Conclusions: Low-frequency EA counteracted a possible prothrombotic state in women with PCOS, as reflected by a decrease in PAI-1 activity. Despite within-group improvements, there were no between-group differences in anthropometric, metabolic, or hemodynamic variables after 16 weeks of EA or physical exercise at the dose/intensity studied.
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| 7. |
- Amrutkar, Manoj, et al.
(author)
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Genetic Disruption of Protein Kinase STK25 Ameliorates Metabolic Defects in a Diet-Induced Type 2 Diabetes Model
- 2015
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In: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 64:8, s. 2791-2804
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Journal article (peer-reviewed)abstract
- Understanding the molecular networks controlling ectopic lipid deposition, glucose tolerance, and insulin sensitivity is essential to identifying new pharmacological approaches to treat type 2 diabetes. We recently identified serine/threonine protein kinase 25 (STK25) as a negative regulator of glucose and insulin homeostasis based on observations in myoblasts with acute depletion of STK25 and in STK25-overexpressing transgenic mice. Here, we challenged Stk25 knockout mice and wild-type littermates with a high-fat diet and showed that STK25 deficiency suppressed development of hyperglycemia and hyperinsulinemia, improved systemic glucose tolerance, reduced hepatic gluconeogenesis, and increased insulin sensitivity. Stk25(-/-) mice were protected from diet-induced liver steatosis accompanied by decreased protein levels of acetyl-CoA carboxylase, a key regulator of both lipid oxidation and synthesis. Lipid accumulation in Stk25(-/-) skeletal muscle was reduced, and expression of enzymes controlling the muscle oxidative capacity (Cpt1, Acox1, Cs, Cycs, Ucp3) and glucose metabolism (Glut1, Glut4, Hk2) was increased. These data are consistent with our previous study of STK25 knockdown in myoblasts and reciprocal to the metabolic phenotype of Stk25 transgenic mice, reinforcing the validity of the results. The findings suggest that STK25 deficiency protects against the metabolic consequences of chronic exposure to dietary lipids and highlight the potential of STK25 antagonists for the treatment of type 2 diabetes.
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| 8. |
- Belda, E., et al.
(author)
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Impairment of gut microbial biotin metabolism and host biotin status in severe obesity: effect of biotin and prebiotic supplementation on improved metabolism
- 2022
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In: Gut. - : BMJ. - 0017-5749 .- 1468-3288. ; 71:12
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Journal article (peer-reviewed)abstract
- Objectives Gut microbiota is a key component in obesity and type 2 diabetes, yet mechanisms and metabolites central to this interaction remain unclear. We examined the human gut microbiome's functional composition in healthy metabolic state and the most severe states of obesity and type 2 diabetes within the MetaCardis cohort. We focused on the role of B vitamins and B7/B8 biotin for regulation of host metabolic state, as these vitamins influence both microbial function and host metabolism and inflammation. Design We performed metagenomic analyses in 1545 subjects from the MetaCardis cohorts and different murine experiments, including germ-free and antibiotic treated animals, faecal microbiota transfer, bariatric surgery and supplementation with biotin and prebiotics in mice. Results Severe obesity is associated with an absolute deficiency in bacterial biotin producers and transporters, whose abundances correlate with host metabolic and inflammatory phenotypes. We found suboptimal circulating biotin levels in severe obesity and altered expression of biotin-associated genes in human adipose tissue. In mice, the absence or depletion of gut microbiota by antibiotics confirmed the microbial contribution to host biotin levels. Bariatric surgery, which improves metabolism and inflammation, associates with increased bacterial biotin producers and improved host systemic biotin in humans and mice. Finally, supplementing high-fat diet-fed mice with fructo-oligosaccharides and biotin improves not only the microbiome diversity, but also the potential of bacterial production of biotin and B vitamins, while limiting weight gain and glycaemic deterioration. Conclusion Strategies combining biotin and prebiotic supplementation could help prevent the deterioration of metabolic states in severe obesity.
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| 9. |
- Benrick, Anna, 1979, et al.
(author)
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Enhanced insulin sensitivity and acute regulation of metabolic genes and signaling pathways after a single electrical or manual acupuncture session in female insulin-resistant rats.
- 2014
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In: Acta Diabetologica. - 0940-5429 .- 1432-5233. ; 51:6, s. 963-972
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Journal article (peer-reviewed)abstract
- AIM: To compare the effect of a single session of acupuncture with either low-frequency electrical or manual stimulation on insulin sensitivity and molecular pathways in the insulin-resistant dihydrotestosterone-induced rat polycystic ovary syndrome (PCOS) model. Both stimulations cause activation of afferent nerve fibers. In addition, electrical stimulation causes muscle contractions, enabling us to differentiate changes induced by activation of sensory afferents from contraction-induced changes. MATERIALS AND METHODS: Control and PCOS rats were divided into no-stimulation, manual-, and electrical stimulation groups and insulin sensitivity was measured by euglycemic hyperinsulinemic clamp. Manually stimulated needles were rotated 180° ten times every 5 min, or low-frequency electrical stimulation was applied to evoke muscle twitches for 45 min. Gene and protein expression were analyzed by real-time PCR and Western blot. RESULTS: The glucose infusion rate (GIR) was lower in PCOS rats than in controls. Electrical stimulation was superior to manual stimulation during treatment but both methods increased GIR to the same extent in the post-stimulation period. Electrical stimulation decreased mRNA expression of Adipor2, Adrb1, Fndc5, Erk2, and Tfam in soleus muscle and increased ovarian Adrb2 and Pdf. Manual stimulation decreased ovarian mRNA expression of Erk2 and Sdnd. Electrical stimulation increased phosphorylated ERK levels in soleus muscle. CONCLUSIONS: One acupuncture session with electrical stimulation improves insulin sensitivity and modulates skeletal muscle gene and protein expression more than manual stimulation. Although electrical stimulation is superior to manual in enhancing insulin sensitivity during stimulation, they are equally effective after stimulation indicating that it is activation of sensory afferents rather than muscle contraction per se leading to the observed changes.
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| 10. |
- Bui, T. P. N., et al.
(author)
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Conversion of dietary inositol into propionate and acetate by commensal Anaerostipes associates with host health
- 2021
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Journal article (peer-reviewed)abstract
- Here, the authors report an anaerobic metabolic pathway from the dominant gut butyrogen Anaerostipes, showing several strains of this genus to be capable of producing propionate from dietary myo-inositol that associates with reduced fasting-glucose levels in mice. We describe the anaerobic conversion of inositol stereoisomers to propionate and acetate by the abundant intestinal genus Anaerostipes. A inositol pathway was elucidated by nuclear magnetic resonance using [C-13]-inositols, mass spectrometry and proteogenomic analyses in A. rhamnosivorans, identifying 3-oxoacid CoA transferase as a key enzyme involved in both 3-oxopropionyl-CoA and propionate formation. This pathway also allowed conversion of phytate-derived inositol into propionate as shown with [C-13]-phytate in fecal samples amended with A. rhamnosivorans. Metabolic and (meta)genomic analyses explained the adaptation of Anaerostipes spp. to inositol-containing substrates and identified a propionate-production gene cluster to be inversely associated with metabolic biomarkers in (pre)diabetes cohorts. Co-administration of myo-inositol with live A. rhamnosivorans in western-diet fed mice reduced fasting-glucose levels comparing to heat-killed A. rhamnosivorans after 6-weeks treatment. Altogether, these data suggest a potential beneficial role for intestinal Anaerostipes spp. in promoting host health.
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