OR03-05 Novel Lipidome Signature in Active Cushing Syndrome Revealed by UHPLC-MS Metabolomics

Background: Alterations in circulating amino acids, polyamines and acylcarnitines have been reported in patients with endogenous chronic hypercortisolism. However, lipid metabolites profiling and its interplay with the serum metabolome and degree of hypercortisolism in patients with active Cushing syndrome (CS) has not been previously assessed. Objective: To identify new metabolomic biomarkers associated with active CS. Methodology: Multiple UHPLC-MS platforms were used to analyze the metabolome of serum samples obtained from 25 patients with active endogenous CS and 25 controls subjects matched by propensity score (sex, BMI, T2D, DLP, HBP). Results: Metabolome of CS patients was deeply disrupted with 122 (27%) of the assessed metabolites significantly altered (p adj. <0.05) out of which 5 bile acids resulted with the highest perturbation (> 2-fold decrease). From the altered metabolites, 3 amino acids (AA), 2 acylcarnitines (ACs), 2 ceramides (CER) and 5 glycerophospholipids showed direction of effect independently associated with 24-h urinary free cortisol (MS) levels. A highly discriminant (AUC 96%) metabolome signature (n=59) characterized by lower levels of AA, ACs, polyunsaturated fatty acids (PUFA) and monoglycerophosphocolines (MGPC) together with increased levels of triacyclglycerols (TG), CER, diacylglycerophosphocholines (DGPC) and cholesteryl esters was identified and cross-validated (R(2)Y= 0.92, Q(2)Y= 0.68) using PLS-DA VIP scores >1.5. PUFA omega-6, and alanine, aspartate and glutamate metabolism resulted the most impacted canonical pathways (q-stat 19.7, 10.8 (p<0.001). Finally, topological network analysis detected 158 pairwise differential correlations (p <0.005, 10,000-fold permutation) between 141 metabolites due to CS where the acylPC (P-18:1/0:0) resulted a key metabolite in the network (betweenness =0.117 & closeness centrality =0.467). Conclusion: Active Cushing syndrome leads to a global proatherogenic shift in the circulating ceramides, glycerophospholipids and sphingolipids metabolites which are independently associated to the levels of urinary free cortisol being potential biomarkers of patients’ cardiovascular risk.