Impairment of gut microbial biotin metabolism and host biotin status in severe obesity: effect of biotin and prebiotic supplementation on improved metabolism

ObjectivesGut 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.DesignWe 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.ResultsSevere 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.ConclusionStrategies combining biotin and prebiotic supplementation could help prevent the deterioration of metabolic states in severe obesity.Trial registration numberNCT02059538.

m6A Regulators in Human Adipose Tissue - Depot-Specificity and Correlation With Obesity

BackgroundN6-methyladenosine (m6A) is one of the most abundant post-transcriptional modifications on mRNA influencing mRNA metabolism. There is emerging evidence for its implication in metabolic disease. No comprehensive analyses on gene expression of m6A regulators in human adipose tissue, especially in paired adipose tissue depots, and its correlation with clinical variables were reported so far. We hypothesized that inter-depot specific gene expression of m6A regulators may differentially correlate with clinical variables related to obesity and fat distribution.MethodsWe extracted intra-individually paired gene expression data (omental visceral adipose tissue (OVAT) N=48; subcutaneous adipose tissue (SAT) N=56) of m6A regulators from an existing microarray dataset. We also measured gene expression in another sample set of paired OVAT and SAT (N=46) using RT-qPCR. Finally, we extracted existing gene expression data from peripheral mononuclear blood cells (PBMCs) and single nucleotide polymorphisms (SNPs) in METTL3 and YTHDF3 from genome wide data from the Sorbs population (N=1049). The data were analysed for differential gene expression between OVAT and SAT; and for association with obesity and clinical variables. We further tested for association of SNP markers with gene expression and clinical traits.ResultsIn adipose tissue we observed that several m6A regulators (WTAP, VIRMA, YTHDC1 and ALKBH5) correlate with obesity and clinical variables. Moreover, we found adipose tissue depot specific gene expression for METTL3, WTAP, VIRMA, FTO and YTHDC1. In PBMCs, we identified ALKBH5 and YTHDF3 correlated with obesity. Genetic markers in METTL3 associate with BMI whilst SNPs in YTHDF3 are associated with its gene expression.ConclusionsOur data show that expression of m6A regulators correlates with obesity, is adipose tissue depot-specific and related to clinical traits. Genetic variation in m6A regulators adds an additional layer of variability to the functional consequences.

Effects of Thymoquinone on Adipocyte Differentiation in Human Adipose-Derived Stem Cells

Background: Obesity is one of the most important public health problems worldwide. Stem cells are primary cells capable of differentiating into different types of cells, and can be used to treat various diseases. Thymoquinone (TQ) has antioxidant, anti-inflammatory, anti-diabetic and anti-obesity properties. Herein, we aim to investigate the effect of TQ on the process of lipid differentiation in human adipose tissue-derived stem cells (ADSCs). Methods and Results: Quantification of cell surface markers was used by Flow-Cytometry and then, the effect of TQ on cell viability was assessed using alamarBlue test. ADSCs were then subjected to induction of differentiation in the presence of non-cytotoxic concentrations of TQ (6.25, 12.5 and 25 μg/mL). ADSCs differentiation was assessed using Oil-Red staining technique. Moreover, expression of PPARγ (Peroxisome proliferator activated receptor γ) and FAS (Fatty Acid Synthetase) proteins was evaluated using Western blotting analysis. Flow-cytometric analysis demonstrated the expression of CD44 and CD90 markers as mesenchymal stem cells markers on the surface of ADSCs. At concentrations≤100 μg/mL of TQ, no significant difference in cell viability of ADSCs was observed compared to the control. Adipocyte differentiation process significantly decreased at 25 μg/mL (P<0.001) and 12.5 μg/mL (P<0.01) of TQ. The results of the qualitative examination of Lipid Droplets also confirmed these results. Western-blot analysis showed that TQ at 12.5 (p<0.05) and 25 μg/mL (p<0.01) reduced FAS/β-actin ratio compared to the positive group.Conclusions: This study showed that TQ can reduce the process of differentiation of fat stem cells into fat cells and might be considered as an anti-obesity compound.

microRNAs in Human Adipose Tissue Physiology and Dysfunction

In recent years, there has been a large amount of evidence on the role of microRNA (miRNA) in regulating adipose tissue physiology. Indeed, miRNAs control critical steps in adipocyte differentiation, proliferation and browning, as well as lipolysis, lipogenesis and adipokine secretion. Overnutrition leads to a significant change in the adipocyte miRNOME, resulting in adipose tissue dysfunction. Moreover, via secreted mediators, dysfunctional adipocytes may impair the function of other organs and tissues. However, given their potential to control cell and whole-body energy expenditure, miRNAs also represent critical therapeutic targets for treating obesity and related metabolic complications. This review attempts to integrate present concepts on the role miRNAs play in adipose tissue physiology and obesity-related dysfunction and data from pre-clinical and clinical studies on the diagnostic or therapeutic potential of miRNA in obesity and its related complications.

Functional Recovery Caused by Human Adipose Tissue Mesenchymal Stem Cell-Derived Extracellular Vesicles Administered 24 h after Stroke in Rats

Ischemic stroke is a major cause of death and disability, intensely demanding innovative and accessible therapeutic strategies. Approaches presenting a prolonged period for therapeutic intervention and new treatment administration routes are promising tools for stroke treatment. Here, we evaluated the potential neuroprotective properties of nasally administered human adipose tissue mesenchymal stem cell (hAT-MSC)-derived extracellular vesicles (EVs) obtained from healthy individuals who underwent liposuction. After a single intranasal EV (200 µg/kg) administered 24 h after a focal permanent ischemic stroke in rats, a higher number of EVs, improvement of the blood–brain barrier, and re-stabilization of vascularization were observed in the recoverable peri-infarct zone, as well as a significant decrease in infarct volume. In addition, EV treatment recovered long-term motor (front paws symmetry) and behavioral impairment (short- and long-term memory and anxiety-like behavior) induced by ischemic stroke. In line with these findings, our work highlights hAT-MSC-derived EVs as a promising therapeutic strategy for stroke.

In Vitro Non-Genomic Effects of Calcifediol on Human Preosteoblastic Cells

Several recent studies have demonstrated that the direct precursor of vitamin D3, the calcifediol [25(OH)D3], through the binding to the nuclear vitamin D receptor (VDR), is able to regulate the expression of many genes involved in several cellular processes. Considering that itself may function as a VDR ligand, although with a lower affinity, respect than the active form of vitamin D, we have assumed that 25(OH)D3 by binding the VDR could have a vitamin’s D3 activity such as activating non-genomic pathways, and in particular we selected mesenchymal stem cells derived from human adipose tissue (hADMSCs) for the in vitro assessment of the intracellular Ca2+ mobilization in response to 25(OH)D3. Our result reveals the ability of 25(OH)D3 to activate rapid, non-genomic pathways, such as an increase of intracellular Ca2+ levels, similar to what observed with the biologically active form of vitamin D3. hADMSCs loaded with Fluo-4 AM exhibited a rapid and sustained increase in intracellular Ca2+ concentration as a result of exposure to 10−5 M of 25(OH)D3. In this work, we show for the first time the in vitro ability of 25(OH)D3 to induce a rapid increase of intracellular Ca2+ levels in hADMSCs. These findings represent an important step to better understand the non-genomic effects of vitamin D3 and its role in endocrine system.