Long-term hypercortisolism induces lipogenesis promoting palmitic acid accumulation and inflammation in visceral adipose tissue compared with HFD-induced obesity.

Glucocorticoids (GCs) play critical roles in adipose tissue metabolism. Here, we compare in a mouse model the effects of chronic glucocorticoid excess and diet-induced obesity on white adipose tissue mass and distribution, by focusing on visceral adipose tissue (VAT) fatty acid composition changes, the role of de novo lipogenesis (DNL) and the inflammatory state. We used a noninvasive mouse model of hypercortisolism to compare GC-induced effects on adipose tissue with diet-induced obesity [high-fat diet (HFD) 45%] and control mice after 10 wk of treatment. Subcutaneous adipose tissue (SAT) and VAT mass and distribution were measured by nuclear magnetic resonance imaging (NMRI). Fatty acid composition in VAT was analyzed by NMR spectroscopy and gas chromatography. Gene expression of key enzymes involved in DNL was analyzed in liver and VAT. Macrophage infiltration markers and proinflammatory cytokines were measured by gene expression in VAT. HFD or GC treatment induced similar fat mass expansion with comparable distribution between SAT and VAT depots. However, in VAT, GCs induce DNL, higher palmitic acid (PA), macrophage infiltration, and proinflammatory cytokine levels, accompanied by systemic nonesterified fatty acid (NEFA) elevation, hyperinsulinemia, and higher homeostatic model assessment for insulin resistance (HOMA-IR) levels compared with diet-induced obesity. Thus, chronic hypercortisolism induces DNL and fatty acid composition changes toward increased SFA and reduced polyunsaturated fatty acid (PUFA) levels in VAT, promoting macrophage recruitment and proinflammatory cytokines, suggesting a worse cardiometabolic profile even compared with HFD mice.

Effects of Bariatric Surgery on Blood and Vascular Large Extracellular Vesicles According to Type 2 Diabetes Status.

CONTEXT: Large extracellular vesicles (lEVs) enriched for endothelial and blood cell markers are increased in metabolic conditions such as obesity or type 2 diabetes (T2D), actively contribute to the atherosclerotic process, and have been identified as diagnostic and prognostic biomarkers for cardiovascular disease (CVD). Although bariatric surgery (BS) in individuals with obesity is related to decreased cardiovascular (CV) risk and increased life expectancy, after BS these subjects are still at higher CV risk than the general population. OBJECTIVE: We aimed to compare the lEV profiles between individuals with obesity, with or without T2D, before and 1 year after BS, and normal-weight controls. METHODS: Prospective longitudinal study with individuals eligible for BS, with or without T2D (T2D and OB groups, respectively) and healthy controls (HC group) matched by age and sex. The concentration and phenotype of lEVs were assessed by flow cytometry. RESULTS: The study cohort included 108 individuals (age 48.0 ± 10.5 years; 84.3% females). Before BS, the OB group presented higher concentrations of lEV enriched for endothelial and blood cell biomarkers than the HC group, but lower concentrations than those observed in the T2D group (P < .05). BS resulted in a significant reduction in most of the lEVs enriched for cell-specific markers in both subgroups. lEV differences between OB and T2D groups were no longer observed after BS (P > .05). However, compared with HC group, OB and T2D groups still showed increased concentrations of lEVs enriched for platelet and endothelial cell markers (P < .05). CONCLUSION: At 1 year after BS, lEV concentrations remain above the physiological range. These abnormalities might contribute to explaining the increased CV risk after BS and underscore the importance of long-term CV risk factor control in post-BS individuals.

Positive Effects of a Mediterranean Diet Supplemented with Almonds on Female Adipose Tissue Biology in Severe Obesity.

It has been suggested that weight-loss-independent Mediterranean diet benefits on cardiometabolic health and diabetes prevention may be mediated, at least in part, through the modulation of white adipose tissue (WAT) biology. This study aimed to evaluate the short-term effects of a dietary intervention based on the Mediterranean diet supplemented with almonds (MDSA) on the main features of obesity-associated WAT dysfunction. A total of 38 women with obesity were randomly assigned to a 3-month intervention with MDSA versus continuation of their usual dietary pattern. Subcutaneous (SAT) and visceral adipose tissue (VAT) biopsies were obtained before and after the dietary intervention, and at the end of the study period, respectively. MDSA favored the abundance of small adipocytes in WAT. In SAT, the expression of angiogenesis genes increased after MDSA intervention. In VAT, the expression of genes implicated in adipogenesis, angiogenesis, autophagy and fatty acid usage was upregulated. In addition, a higher immunofluorescence staining for PPARG, CD31+ cells and M2-like macrophages and increased ADRB1 and UCP2 protein contents were found compared to controls. Changes in WAT correlated with a significant reduction in circulating inflammatory markers and LDL-cholesterol levels. These results support a protective effect of a Mediterranean diet supplemented with almonds on obesity-related WAT dysfunction.

Low Percentage of Vegetable Fat in Red Blood Cells Is Associated with Worse Glucose Metabolism and Incidence of Type 2 Diabetes.

The identification of nutritional patterns associated with the development of type 2 diabetes (T2D) might help lead the way to a more efficient and personalized nutritional intervention. Our study is aimed at evaluating the association between fatty acids (FA) in red blood cell (RBC) membranes, as a quantitative biomarker of regular dietary fat intake, and incident type 2 diabetes in a Spanish population. We included 1032 adult Spaniards (57% women, age 49 ± 15 years, 18% prediabetes), without diabetes at study entry, from the Di@bet.es cohort. Incident diabetes was diagnosed at the end of the study follow-up. The FA percentage in RBC was determined at baseline by gas chromatography. Participants were followed on average 7.5 ± 0.6 years. Lower percentages of linoleic acid (LA), α-linolenic (ALA), and eicosapentaenoic acid (EPA), and higher percentages of docosahexaenoic acid (DHA) in RBC membranes were associated, independently of classical risk factors, with worse glucose metabolism at the end of the study follow-up. In addition, higher percentages of ALA and EPA, and moderate percentages of DHA, were associated with lower risk of diabetes. No significant associations were found for LA and diabetes risk. Dietary patterns rich in vegetables are independently associated with lower risk of both deterioration of glucose regulation and incident diabetes, and should be reinforced for the prevention of diabetes.

Enrichment of Astrocyte-Derived Extracellular Vesicles from Human Plasma.

Extracellular vesicles (EVs) are biological nanoparticles secreted by all cells for cellular communication and waste elimination. They participate in a vast range of functions by acting on and transferring their cargos to other cells in physiological and pathological conditions. Given their presence in biofluids, EVs represent an excellent resource for studying disease processes and can be considered a liquid biopsy for biomarker discovery. An attractive aspect of EV analysis is that they can be selected based on markers of their cell of origin, thus reflecting the environment of a specific tissue in their cargo. However, one of the major handicaps related to EV isolation methods is the lack of methodological consensuses and standardized protocols. Astrocytes are glial cells with essential roles in the brain. In neurodegenerative diseases, astrocyte reactivity may lead to altered EV cargo and aberrant cellular communication, facilitating/enhancing disease progression. Thus, analysis of astrocyte EVs may lead to the discovery of biomarkers and potential disease targets. This protocol describes a 2-step method of enrichment of astrocyte-derived EVs (ADEVs) from human plasma. First, EVs are enriched from defibrinated plasma via polymer-based precipitation. This is followed by enrichment of ADEVs through ACSA-1-based immunocapture with magnetic micro-beads, where resuspended EVs are loaded onto a column placed in a magnetic field. Magnetically labeled ACSA-1+ EVs are retained within the column, while other EVs flow through. Once the column is removed from the magnet, ADEVs are eluted and are ready for storage and analysis. To validate the enrichment of astrocyte markers, glial fibrillary acidic protein (GFAP), or other specific astrocytic markers of intracellular origin, can be measured in the eluate and compared with the flow-through. This protocol proposes an easy, time-efficient method to enrich ADEVs from plasma that can be used as a platform to examine astrocyte-relevant markers.

Glucocorticoid-induced Fingerprints on Visceral Adipose Tissue Transcriptome and Epigenome.

CONTEXT: Chronic glucocorticoid (GC) overexposure, resulting from endogenous Cushing's syndrome (CS) or exogenous GC therapy, causes several adverse outcomes, including persistent central fat accumulation associated with a low-grade inflammation. However, no previous multiomics studies in visceral adipose tissue (VAT) from patients exposed to high levels of unsuppressed GC during active CS or after remission are available yet. OBJECTIVE: To determine the persistent VAT transcriptomic alterations and epigenetic fingerprints induced by chronic hypercortisolism. METHODS: We employed a translational approach combining high-throughput data on endogenous CS patients and a reversible CS mouse model. We performed RNA sequencing and chromatin immunoprecipitation sequencing on histone modifications (H3K4me3, H3K27ac, and H3K27me3) to identify persistent transcriptional and epigenetic signatures in VAT produced during active CS and maintained after remission. RESULTS: VAT dysfunction was associated with low-grade proinflammatory status, macrophage infiltration, and extracellular matrix remodeling. Most notably, chronic hypercortisolism caused a persistent circadian rhythm disruption in VAT through core clock genes modulation. Importantly, changes in the levels of 2 histone modifications associated to gene transcriptional activation (H3K4me3 and H3K27ac) correlated with the observed differences in gene expression during active CS and after CS remission. CONCLUSION: We identified for the first time the persistent transcriptional and epigenetic signatures induced by hypercortisolism in VAT, providing a novel integrated view of molecular components driving the long-term VAT impairment associated with CS.

Extracellular vesicles in atherothrombosis and cardiovascular disease: Friends and foes.

Extracellular vesicles (EV, exosomes and microvesicles -MV-) are 30-1000 nm particles surrounded by a phospholipid bilayer membrane that are released from almost all cell types through several pathways. EV encapsulate bioactive molecules, and the molecular cargo is determined by the trigger stimulating its release, reflecting its cell origin and biological functions. This review is primarily focused on the latest evidence of the roles of EV, released from cells involved in the different stages of atherothrombosis. The potential translation of this information to the clinical arena is also discussed. EV can have both pro- and anti-atherothrombotic effects depending on several factors, such as the type of vesicle (MV/exosome), its molecular cargo, its cell of origin, and the context in which are generated, i.e., the stimulus triggering its release. In fact, EV actively participate in every step of atherosclerosis onset and progression, and also in thrombus formation leading to a major adverse cardiovascular event. Moreover, EV have a determinant role in fibrous cap stability, thus determining the propensity of the plaque to rupture. On the other hand, and again, conditioned by the context and stimulus instigating its secretion, some EV may have protective biological functions, perhaps as a compensatory mechanism or even with reparative or regenerative potential. Therefore, the study of the implication of EV in atherothrombosis might be of relevance to unveil new therapeutic targets, vectors and biomarkers of cardiovascular disease (CVD).

Endogenous cortisol excess confers a unique lipid signature and metabolic network.

Chronic cortisol excess induces several alterations on protein, lipid and carbohydrate metabolism resembling those found in the metabolic syndrome. However, patients exposed to prolonged high levels of cortisol in Cushing syndrome (CS) present exceeding cardiometabolic alterations not reflected by conventional biomarkers. Using 3 ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS) platforms, we aimed to characterise the serum metabolome of 25 patients with active endogenous CS and 25 control subjects matched by propensity score (sex, BMI, diabetes mellitus type 2 (T2D), high blood pressure (HBP) and dyslipidaemia) to search for potential disease-specific biomarkers and pathways associated to the clinical comorbidities. A total of 93 metabolites were significantly altered in patients with CS. Increased levels of sulfur amino acids (AA), triacylglycerols, glycerophospholipids, ceramides and cholesteryl esters were observed. Contrarily, concentrations of essential and non-essential AA, polyunsaturated fatty acids, conjugated bile acids and second messenger glycerolipids were decreased. Twenty-four-hour urinary free cortisol (24h-UFC) independently determined the concentration of 21 lipids and 4 AA. A metabolic signature composed by 10 AA and 10 lipid metabolites presented an AUC-ROC of 95% for the classification of CS patients. Through differential network analysis, 152 aberrant associations between metabolites involved in the Lands cycle and Kennedy pathway were identified. Our data indicates that chronic hypercortisolemia confers a unique lipidomic signature and several alterations in numerous AA even when compared to patients with similar metabolic comorbidities providing novel insights of the increased cardiometabolic burden of CS. KEY MESSAGES: • Cortisol excess induces metabolic alterations beyond conventional biomarkers. • The hypercortisolism extent determines the concentration of 21 lipids and 5 aa. • Cortisol excess confers a unique metabolic signature of 20 metabolites. • Kennedy and Lands cycle are profoundly disturbed by cortisol excess.

Chronic hypercortisolism causes more persistent visceral adiposity than HFD-induced obesity.

Excessive and prolonged glucocorticoid (GC) exposure, resulting from either prescribed or endogenous hypercortisolism, is associated with a high cardiovascular and metabolic burden (Cushing's syndrome). Although previous studies in humans and mice have reported heterogeneous data about the persistence of metabolic syndrome features after remission of hypercortisolism, there is still controversy as to whether this is due to the deleterious changes induced by GCs during active disease or the result of various other factors interfering in the recovery period. In order to study metabolic effects after remission, we used a reversible mouse model of corticosterone (CORT) (100 µg/mL) administration in drinking water for 5 weeks, followed by a 10-week recovery period. We compared CORT-induced effects at these time points with a high-fat diet-treated group (HFD 45%) and a vehicle group (VEH). Plasma CORT, 11ß-HSD activity, food intake, glucose levels, interscapular brown adiposity, hepatic triglycerides and muscle mass were found altered during CORT treatment but normalized after recovery. Although hyperinsulinemia and insulin resistance were increased during CORT and HFD treatment, insulin homeostasis remained altered following the recovery period only in CORT-treated mice. Subcutaneous and visceral adipose tissues (SAT and VAT) were enlarged during HFD and CORT treatment as measured by MRI. However, increased muscle lipid content, adiposity and macrophage infiltration in VAT were only present in the CORT group following recovery. Taken together, CORT-induced insulin alterations were more potent than HFD-induced ones during the same period of treatment, and also more persistent long term. Moreover, we demonstrated that CORT treatment induces more long-lasting VAT enlargement than HFD.