Lipidomics and biodistribution of extracellular vesicles-secreted by hepatocytes from Zucker lean and fatty rats.

Extracellular vesicles (EVs) have been involved in metabolic syndrome, although their specific role in the development of the pathology is still unknown. To further study the role of EVs, we have analysed by Raman tweezers microspectroscopy and mass spectrometry-based lipidomics the small EVs population secreted by fatty (ZF) and lean (ZL) hepatocytes obtained from Zucker rats. We have also explored in vivo and ex vivo biodistribution of these EVs through fluorine-18-radiolabelling using a positron emission tomography imaging. Based on the proportion of proteins to lipids and the types of lipids, our results indicate that within the range of small EVs, primary hepatocytes secrete different subpopulations of particles. These differences were observed in the enrichment of triglyceride species in EVs secreted by ZF hepatocytes. Biodistribution experiments showed accumulation in the brain, heart, lungs, kidney and specially in bladder after intravenous administration. In summary, we show that EVs released by a fatty hepatocytes carry a different lipid signature compared to their lean counterpart. Biodistribution experiment has shown no difference in the distribution of EVs secreted by ZF and ZL hepatocytes but has given us a first view of possible target organs for these particles. Our results might open a door to both pathology studies and therapeutic interventions.

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.