A dynamic association between myosteatosis and liver stiffness: Results from a prospective interventional study in obese patients

Background & Aims

Retrospective cross-sectional studies linked sarcopenia and myosteatosis with metabolic dysfunction-associated fatty liver disease (MAFLD). Here, we wanted to clarify the dynamic relationship between sarcopenia, myosteatosis, and MAFLD.

Methods

A cohort of 48 obese patients was randomised for a dietary intervention consisting of 16 g/day of inulin (prebiotic) or maltodextrin (placebo) supplementation. Before and after the intervention, we evaluated liver steatosis and stiffness with transient elastography (TE); we assessed skeletal muscle index (SMI) and skeletal muscle fat index (SMFI) (a surrogate for absolute fat content in muscle) using computed tomography (CT) and bioelectrical impedance analysis (BIA).

Results

At baseline, sarcopenia was uncommon in patients with MAFLD (4/48, 8.3%). SMFI was higher in patients with high liver stiffness than in those with low liver stiffness (640.6 ± 114.3 cm²/ Hounsfield unit [HU] vs. 507.9 ± 103.0 cm²/HU, p = 0.001). In multivariate analysis, SMFI was robustly associated with liver stiffness even when adjusted for multiple confounders (binary logistic regression, p <0.05). After intervention, patients with inulin supplementation lost weight, but this was not associated with a decrease in liver stiffness. Remarkably, upon intervention (being inulin or maltodextrin), patients who lowered their SMFI, but not those who increased SMI, had a 12.7% decrease in liver stiffness (before = 6.36 ± 2.15 vs. after = 5.55 ± 1.97 kPa, p = 0.04).

Conclusions

Myosteatosis, but not sarcopenia, is strongly and independently associated with liver stiffness in obese patients with MAFLD. After intervention, patients in which the degree of myosteatosis decreased reduced their liver stiffness, irrespective of body weight loss or prebiotic treatment. The potential contribution of myosteatosis to liver disease progression should be investigated.

Clinical Trials registration number

NCT03852069.

Lay summary

The fat content in skeletal muscles (or myosteatosis) is strongly associated with liver stiffness in obese patients with MAFLD. After a dietary intervention, patients in which the degree of myosteatosis decreased also reduced their liver stiffness. The potential contribution of myosteatosis to liver disease progression should be investigated.

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Low-radiation CT scan enables muscle evaluation (quantity and composition).

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Muscle mass is not low in patients with MAFLD and high liver stiffness.

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In contrast, myosteatosis is strongly associated with liver stiffness.

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Lower myosteatosis after dietary intervention is associated with improved MAFLD.

Effects of Saffron Extract on Sleep Quality: A Randomized Double-Blind Controlled Clinical Trial

A saffron extract has been found to be effective in the context of depression and anxiety, but its effect on sleep quality has not been investigating yet using objective approaches. For this purpose, a randomized double-blind controlled study was conducted in subjects presenting mild to moderate sleep disorder associated with anxiety. Sixty-six subjects were randomized and supplemented with a placebo (maltodextrin) or a saffron extract (15.5 mg per day) for 6 weeks. Actigraphy was used to collect objective data related to sleep quality at baseline, at the middle and at the end of the intervention. Sleep quality was also assessed by completion of the LSEQ and PSQI questionnaires and quality of life by completion of the SF-36 questionnaire. Six weeks of saffron supplementation led to an increased time in bed assessed by actigraphy, to an improved ease of getting to sleep evaluated by the LSEQ questionnaire and to an improved sleep quality, sleep latency, sleep duration, and global scores evaluated by the PSQI questionnaire, whereas those parameters were not modified by the placebo. In conclusion, those results suggest that a saffron extract could be a natural and safe nutritional strategy to improve sleep duration and quality.

Discovery of the gut microbial signature driving the efficacy of prebiotic intervention in obese patients

OBJECTIVE

The gut microbiota has been proposed as an interesting therapeutic target for metabolic disorders. Inulin as a prebiotic has been shown to lessen obesity and related diseases. The aim of the current study was to investigate whether preintervention gut microbiota characteristics determine the physiological response to inulin.

DESIGN

The stools from four obese donors differing by microbial diversity and composition were sampled before the dietary intervention and inoculated to antibiotic-pretreated mice (hum-ob mice; humanised obese mice). Hum-ob mice were fed with a high-fat diet and treated with inulin. Metabolic and microbiota changes on inulin treatment in hum-ob mice were compared with those obtained in a cohort of obese individuals supplemented with inulin for 3 months.

RESULTS

We show that hum-ob mice colonised with the faecal microbiota from different obese individuals differentially respond to inulin supplementation on a high-fat diet. Among several bacterial genera, Barnesiella, Bilophila, Butyricimonas, Victivallis, Clostridium XIVa, Akkermansia, Raoultella and Blautia correlated with the observed metabolic outcomes (decrease in adiposity and hepatic steatosis) in hum-ob mice. In addition, in obese individuals, the preintervention levels of Anaerostipes, Akkermansia and Butyricicoccus drive the decrease of body mass index in response to inulin.

CONCLUSION

These findings support that characterising the gut microbiota prior to nutritional intervention with prebiotics is important to increase the positive outcome in the context of obesity and metabolic disorders.

Effects of a diet based on inulin-rich vegetables on gut health and nutritional behavior in healthy humans

BACKGROUND

Inulin-type fructans (ITFs) are a type of fermentable dietary fiber that can confer beneficial health effects through changes in the gut microbiota. However, their effect on gut sensitivity and nutritional behavior is a matter of debate.

OBJECTIVE

We evaluated the impact of consuming ITF-rich vegetables daily on gut microbiota, gastro-intestinal symptoms, and food-related behavior in healthy individuals.

METHODS

A single group-design trial was conducted in 26 healthy individuals. During 2 wk, the participants were instructed to adhere to a controlled diet based on ITF-rich vegetables (providing a mean intake of 15 g ITF/d). Three test days were organized: before and after the nutritional intervention and 3 wk after returning to their usual diet. We assessed nutrient intake, food-related behavior, fecal microbiota composition, microbial fermentation, and gastrointestinal symptoms.

RESULTS

The major microbial modifications during the intervention were an increased proportion of the Bifidobacterium genus, a decreased level of unclassified Clostridiales, and a tendency to decrease Oxalobacteraceae. These changes were reversed 3 wk after the intervention. The volunteers showed greater satiety, a reduced desire to eat sweet, salty, and fatty food, and a trend to increase hedonic attitudes towards some inulin-rich vegetables. Only flatulence episodes were reported during the dietary intervention, whereas intestinal discomfort, inversely associated with Clostridium cluster IV and Ruminococcus callidus, was improved at the end of the intervention.

CONCLUSIONS

A higher consumption of ITF-rich vegetables allows a substantial increase in well-tolerated dietary fiber, which may in turn improve food-related behavior. Moreover, it leads to beneficial modifications of the gut microbiota composition and function. This trial is registered at clinicaltrial.gov as NCT03540550.

Inulin Improves Postprandial Hypertriglyceridemia by Modulating Gene Expression in the Small Intestine

Postprandial hyperlipidemia is an important risk factor for cardiovascular diseases in the context of obesity. Inulin is a non-digestible carbohydrate, known for its beneficial properties in metabolic disorders. We investigated the impact of inulin on postprandial hypertriglyceridemia and on lipid metabolism in a mouse model of diet-induced obesity. Mice received a control or a western diet for 4 weeks and were further supplemented or not with inulin for 2 weeks (0.2 g/day per mouse). We performed a lipid tolerance test, measured mRNA expression of genes involved in postprandial lipid metabolism, assessed post-heparin plasma and muscle lipoprotein lipase activity and measured lipid accumulation in the enterocytes and fecal lipid excretion. Inulin supplementation in western diet-fed mice decreases postprandial serum triglycerides concentration, decreases the mRNA expression levels of Cd36 (fatty acid receptor involved in lipid uptake and sensing) and apolipoprotein C3 (Apoc3, inhibitor of lipoprotein lipase) in the jejunum and increases fecal lipid excretion. In conclusion, inulin improves postprandial hypertriglyceridemia by targeting intestinal lipid metabolism. This work confirms the interest of using inulin supplementation in the management of dyslipidemia linked to obesity and cardiometabolic risk.

Implication of trans-11,trans-13 conjugated linoleic acid in the development of hepatic steatosis

SCOPE

Conjugated linoleic acids are linoleic acid isomers found in the diet that can also be produced through bacterial metabolism of polyunsaturated fatty acids. Our objective was to evaluate the contribution of fatty acid metabolites produced from polyunsaturated fatty acids by the gut microbiota in vivo to regulation of hepatic lipid metabolism and steatosis.

METHODS AND RESULTS

In mice with depleted n-3 polyunsaturated fatty acids, we observed an accumulation of trans-11,trans-13 CLA and cis-9,cis-11 conjugated linoleic acids in the liver tissue that were associated with an increased triglyceride content and expression of lipogenic genes. We used an in vitro model to evaluate the impact of these two conjugated linoleic acids on hepatic lipid metabolism. In HepG2 cells, we observed that only trans-11,trans-13 conjugated linoleic acids recapitulated triglyceride accumulation and increased lipogenic gene expression, which is a phenomenon that may implicate the nuclear factors sterol regulatory element binding protein 1c (SREBP-1c) and carbohydrate-responsive element-binding protein (ChREBP).

CONCLUSION

The trans-11,trans-13 conjugated linoleic acids can stimulate hepatic lipogenesis, which supports the conclusion that gut microbiota and related metabolites should be considered in the treatment of non-alcoholic liver disease.

Targeting the gut microbiota with inulin-type fructans: preclinical demonstration of a novel approach in the management of endothelial dysfunction

OBJECTIVE

To investigate the beneficial role of prebiotics on endothelial dysfunction, an early key marker of cardiovascular diseases, in an original mouse model linking steatosis and endothelial dysfunction.

DESIGN

We examined the contribution of the gut microbiota to vascular dysfunction observed in apolipoprotein E knockout (Apoe^-/-) mice fed an n-3 polyunsaturated fatty acid (PUFA)-depleted diet for 12 weeks with or without inulin-type fructans (ITFs) supplementation for the last 15 days. Mesenteric and carotid arteries were isolated to evaluate endothelium-dependent relaxation ex vivo. Caecal microbiota composition (Illumina Sequencing of the 16S rRNA gene) and key pathways/mediators involved in the control of vascular function, including bile acid (BA) profiling, gut and liver key gene expression, nitric oxide and gut hormones production were also assessed.

RESULTS

ITF supplementation totally reverses endothelial dysfunction in mesenteric and carotid arteries of n-3 PUFA-depleted Apoe^-/- mice via activation of the nitric oxide (NO) synthase/NO pathway. Gut microbiota changes induced by prebiotic treatment consist in increased NO-producing bacteria, replenishment of abundance in Akkermansia and decreased abundance in bacterial taxa involved in secondary BA synthesis. Changes in gut and liver gene expression also occur upon ITFs suggesting increased glucagon-like peptide 1 production and BA turnover as drivers of endothelium function preservation.

CONCLUSIONS

We demonstrate for the first time that ITF improve endothelial dysfunction, implicating a short-term adaptation of both gut microbiota and key gut peptides. If confirmed in humans, prebiotics could be proposed as a novel approach in the prevention of metabolic disorders-related cardiovascular diseases.

Nutritional depletion in n-3 PUFA in apoE knock-out mice: A new model of endothelial dysfunction associated with fatty liver disease

SCOPE

Western diets are characterized by low intake of n-3 PUFA compensated by constant amounts of n-6 PUFA. Reduced intake of n-3 PUFA is associated with increased cardiovascular risk, as observed in nonalcoholic fatty liver disease patients. The study aimed to evaluating the impact of dietary n-3 PUFA depletion on endothelial function, an early key event of cardiovascular diseases.

METHODS AND RESULTS

C57Bl/6J or apolipoprotein E knock-out (apoE^-/- ) were fed control (CT) or n-3 PUFA-depleted diets (DEF) for 12 wks. Mice fed n-3 DEF diet developed a hepatic steatosis, linked to changes in hepatic expression of genes controlled by Sterol Regulatory Element Binding Protein-1 and -2. Vascular function was assessed on second- and third-order mesenteric arteries and n-3 PUFA-depleted apoE^-/- mice presented endothelial dysfunction characterized by decreased vasorelaxation in response of acetylcholine. The presence of a nitric oxide synthase (NOS) inhibitor blunted the relaxation in each groups and heme-nitrosylated hemoglobin blood (Hb-NO) level was significantly lower in n-3 PUFA-depleted apoE^-/- mice.

CONCLUSION

Twelve weeks of n-3 DEF diet promote steatosis and accelerate the process of endothelial dysfunction in apoE^-/- mice by a mechanism involving the NOS/NO pathway. We propose n-3 PUFA-depleted apoE^-/- mice as a new model to study endothelial dysfunction related to hepatic steatosis independently of obesity.

Prebiotic approach alleviates hepatic steatosis: implication of fatty acid oxidative and cholesterol synthesis pathways

SCOPE

Recent data suggest that gut microbiota contributes to the regulation of host lipid metabolism. We report how fermentable dietary fructo-oligosaccharides (FOS) control hepatic steatosis induced by n-3 PUFA depletion, which leads to hepatic alterations similar to those observed in non-alcoholic fatty liver disease patients.

METHODS AND RESULTS

C57Bl/6J mice fed an n-3 PUFA-depleted diet for 3 months were supplemented with FOS during the last 10 days of treatment. FOS-treated mice exhibited higher caecal Bifidobacterium spp. and lower Roseburia spp. content. Microarray analysis of hepatic mRNA revealed that FOS supplementation reduced hepatic triglyceride accumulation through a proliferator-activated receptor α-stimulation of fatty acid oxidation and lessened cholesterol accumulation by inhibiting sterol regulatory element binding protein 2-dependent cholesterol synthesis. Cultured precision-cut liver slices confirmed the inhibition of fatty acid oxidation. FOS effects were related to a decreased hepatic micro-RNA33 expression and to an increased colonic glucagon-like peptide 1 production.

CONCLUSIONS

The changes in gut microbiota composition by n-3 PUFA-depletion and prebiotics modulate hepatic steatosis by changing gene expression in the liver, a phenomenon that could implicate micro-RNA and gut-derived hormones. Our data underline the advantage of targeting the gut microbiota by colonic nutrients in the management of liver disease.

Restoring specific lactobacilli levels decreases inflammation and muscle atrophy markers in an acute leukemia mouse model

The gut microbiota has recently been proposed as a novel component in the regulation of host homeostasis and immunity. We have assessed for the first time the role of the gut microbiota in a mouse model of leukemia (transplantation of BaF3 cells containing ectopic expression of Bcr-Abl), characterized at the final stage by a loss of fat mass, muscle atrophy, anorexia and inflammation. The gut microbial 16S rDNA analysis, using PCR-Denaturating Gradient Gel Electrophoresis and quantitative PCR, reveals a dysbiosis and a selective modulation of Lactobacillus spp. (decrease of L. reuteri and L. johnsonii/gasseri in favor of L. murinus/animalis) in the BaF3 mice compared to the controls. The restoration of Lactobacillus species by oral supplementation with L. reuteri 100-23 and L. gasseri 311476 reduced the expression of atrophy markers (Atrogin-1, MuRF1, LC3, Cathepsin L) in the gastrocnemius and in the tibialis, a phenomenon correlated with a decrease of inflammatory cytokines (interleukin-6, monocyte chemoattractant protein-1, interleukin-4, granulocyte colony-stimulating factor, quantified by multiplex immuno-assay). These positive effects are strain- and/or species-specific since L. acidophilus NCFM supplementation does not impact on muscle atrophy markers and systemic inflammation. Altogether, these results suggest that the gut microbiota could constitute a novel therapeutic target in the management of leukemia-associated inflammation and related disorders in the muscle.

Hepatic n-3 polyunsaturated fatty acid depletion promotes steatosis and insulin resistance in mice: genomic analysis of cellular targets

Patients with non-alcoholic fatty liver disease are characterised by a decreased n-3/n-6 polyunsaturated fatty acid (PUFA) ratio in hepatic phospholipids. The metabolic consequences of n-3 PUFA depletion in the liver are poorly understood. We have reproduced a drastic drop in n-3 PUFA among hepatic phospholipids by feeding C57Bl/6J mice for 3 months with an n-3 PUFA depleted diet (DEF) versus a control diet (CT), which only differed in the PUFA content. DEF mice exhibited hepatic insulin resistance (assessed by euglycemic-hyperinsulinemic clamp) and steatosis that was associated with a decrease in fatty acid oxidation and occurred despite a higher capacity for triglyceride secretion. Microarray and qPCR analysis of the liver tissue revealed higher expression of all the enzymes involved in lipogenesis in DEF mice compared to CT mice, as well as increased expression and activation of sterol regulatory element binding protein-1c (SREBP-1c). Our data suggest that the activation of the liver X receptor pathway is involved in the overexpression of SREBP-1c, and this phenomenon cannot be attributed to insulin or to endoplasmic reticulum stress responses. In conclusion, n-3 PUFA depletion in liver phospholipids leads to activation of SREBP-1c and lipogenesis, which contributes to hepatic steatosis.

Involvement of gut microbial fermentation in the metabolic alterations occurring in n-3 polyunsaturated fatty acids-depleted mice

Backround

Western diet is characterized by an insufficient n-3 polyunsaturated fatty acid (PUFA) consumption which is known to promote the pathogenesis of several diseases. We have previously observed that mice fed with a diet poor in n-3 PUFA for two generations exhibit hepatic steatosis together with a decrease in body weight. The gut microbiota contributes to the regulation of host energy metabolism, due to symbiotic relationship with fermentable nutrients provided in the diet. In this study, we have tested the hypothesis that perturbations of the gut microbiota contribute to the metabolic alterations occurring in mice fed a diet poor in n-3 PUFA for two generations (n-3/- mice).

Methods

C57Bl/6J mice fed with a control or an n-3 PUFA depleted diet for two generations were supplemented with prebiotic (inulin-type Fructooligosaccharides, FOS, 0.20 g/day/mice) during 24 days.

Results

n-3/-mice exhibited a marked drop in caecum weight, a decrease in lactobacilli and an increase in bifidobacteria in the caecal content as compared to control mice (n-3/+ mice). Dietary supplementation with FOS for 24 days was sufficient to increase caecal weight and bifidobacteria count in both n-3/+ and n-3/-mice. Moreover, FOS increased lactobacilli content in n-3/-mice, whereas it decreased their level in n-3/+ mice. Interestingly, FOS treatment promoted body weight gain in n-3/-mice by increasing energy efficiency. In addition, FOS treatment decreased fasting glycemia and lowered the higher expression of key factors involved in the fatty acid catabolism observed in the liver of n-3/-mice, without lessening steatosis.

Conclusions

the changes in the gut microbiota composition induced by FOS are different depending on the type of diet. We show that FOS may promote lactobacilli and counteract the catabolic status induced by n-3 PUFA depletion in mice, thereby contributing to restore efficient fat storage.

Changes in intestinal bifidobacteria levels are associated with the inflammatory response in magnesium-deficient mice

Magnesium (Mg) deficiency is a common nutritional disorder that is linked to an inflammatory state characterized by increased plasma acute phase protein and proinflammatory cytokine concentrations. Recent studies have shown that changes in the composition of gut microbiota composition participate in systemic inflammation. In this study, therefore, we assessed the potential role of gut microbiota in intestinal and systemic inflammation associated with Mg deficiency in mice. For this purpose, mice were fed a control or Mg-deficient diet (500 mg vs. 70 mg Mg/kg) for 4 or 21 d. Compared with the mice fed the control diet, mice fed the Mg-deficient diet for 4 d had a lower gut bifidobacteria content (-1.5 log), a 36-50% lower mRNA content of factors controlling gut barrier function in the ileum (zonula occludens-1, occludin, proglucagon), and a higher mRNA content (by approximately 2-fold) in the liver and/or intestine of tumor necrosis factor-alpha, interleukin-6, CCAAT/enhancer binding protein homologous protein, and activating transcription factor 4, reflecting inflammatory and cellular stress. In contrast, mice fed the Mg-deficient diet for 21 d had a higher cecal bifidobacteria content compared with the control group, a phenomenon accompanied by restoration of the intestinal barrier and the absence of inflammation. In conclusion, we show that Mg deficiency, independently of any other changes in nutrient intake, modulates the concentration of bifidobacteria in the gut, a phenomenon that may time-dependently affect inflammation and metabolic disorders in mice.

Gut microbiota fermentation of prebiotics increases satietogenic and incretin gut peptide production with consequences for appetite sensation and glucose response after a meal

BACKGROUND

We have previously shown that gut microbial fermentation of prebiotics promotes satiety and lowers hunger and energy intake in humans. In rodents, these effects are associated with an increase in plasma gut peptide concentrations, which are involved in appetite regulation and glucose homeostasis.

OBJECTIVE

Our aim was to examine the effects of prebiotic supplementation on satiety and related hormones during a test meal for human volunteers by using a noninvasive micromethod for blood sampling to measure plasma gut peptide concentrations.

DESIGN

This study was a randomized, double-blind, parallel, placebo-controlled trial. A total of 10 healthy adults (5 men and 5 women) were randomly assigned to groups that received either 16 g prebiotics/d or 16 g dextrin maltose/d for 2 wk. Meal tolerance tests were performed in the morning to measure the following: hydrogen breath test, satiety, glucose homeostasis, and related hormone response.

RESULTS

We show that the prebiotic treatment increased breath-hydrogen excretion (a marker of gut microbiota fermentation) by approximately 3-fold and lowered hunger rates. Prebiotics increased plasma glucagon-like peptide 1 and peptide YY concentrations, whereas postprandial plasma glucose responses decreased after the standardized meal. The areas under the curve for plasma glucagon-like peptide 1 and breath-hydrogen excretion measured after the meal (0-60 min) were significantly correlated (r = 0.85, P = 0.007). The glucose response was inversely correlated with the breath-hydrogen excretion areas under the curve (0-180 min; r = -0.73, P = 0.02).

CONCLUSION

Prebiotic supplementation was associated with an increase in plasma gut peptide concentrations (glucagon-like peptide 1 and peptide YY), which may contribute in part to changes in appetite sensation and glucose excursion responses after a meal in healthy subjects.

Hepatic steatosis in n-3 fatty acid depleted mice: focus on metabolic alterations related to tissue fatty acid composition

Background

There are only few data relating the metabolic consequences of feeding diets very low in n-3 fatty acids. This experiment carried out in mice aims at studying the impact of dietary n-3 polyunsaturated fatty acids (PUFA) depletion on hepatic metabolism.

Results

n-3 PUFA depletion leads to a significant decrease in body weight despite a similar caloric intake or adipose tissue weight. n-3 PUFA depleted mice exhibit hypercholesterolemia (total, HDL, and LDL cholesterol) as well as an increase in hepatic cholesteryl ester and triglycerides content. Fatty acid pattern is profoundly modified in hepatic phospholipids and triglycerides. The decrease in tissue n-3/n-6 PUFA ratio correlates with steatosis. Hepatic mRNA content of key factors involved in lipid metabolism suggest a decreased lipogenesis (SREBP-1c, FAS, PPARγ), and an increased β-oxidation (CPT1, PPARα and PGC1α) without modification of fatty acid esterification (DGAT2, GPAT1), secretion (MTTP) or intracellular transport (L-FABP). Histological analysis reveals alterations of liver morphology, which can not be explained by inflammatory or oxidative stress. However, several proteins involved in the unfolded protein response are decreased in depleted mice.

Conclusion

n-3 PUFA depletion leads to important metabolic alterations in murine liver. Steatosis occurs through a mechanism independent of the shift between β-oxidation and lipogenesis. Moreover, long term n-3 PUFA depletion decreases the expression of factors involved in the unfolded protein response, suggesting a lower protection against endoplasmic reticulum stress in hepatocytes upon n-3 PUFA deficiency.