Ganglioside GM3 Protects Against Abdominal Aortic Aneurysm by Suppressing Ferroptosis.

BACKGROUND: Abdominal aortic aneurysm (AAA) is a potentially life-threatening vascular condition, but approved medical therapies to prevent AAA progression and rupture are currently lacking. Sphingolipid metabolism disorders are associated with the occurrence and development of AAA. It has been discovered that ganglioside GM3, a sialic acid-containing type of glycosphingolipid, plays a protective role in atherosclerosis, which is an important risk factor for AAA; however, the potential contribution of GM3 to AAA development has not been investigated. METHODS: We performed a metabolomics study to evaluated GM3 level in plasma of human patients with AAA. We profiled GM3 synthase (ST3GAL5) expression in the mouse model of aneurysm and human AAA tissues through Western blotting and immunofluorescence staining. RNA sequencing, affinity purification and mass spectrometry, proteomic analysis, surface plasmon resonance analysis, and functional studies were used to dissect the molecular mechanism of GM3-regulating ferroptosis. We conditionally deleted and overexpressed St3gal5 in smooth muscle cells (SMCs) in vivo to investigate its role in AAA. RESULTS: We found significantly reduced plasma levels of GM3 in human patients with AAA. GM3 content and ST3GAL5 expression were decreased in abdominal aortic vascular SMCs in patients with AAA and an AAA mouse model. RNA sequencing analysis showed that ST3GAL5 silencing in human aortic SMCs induced ferroptosis. We showed that GM3 interacted directly with the extracellular domain of TFR1 (transferrin receptor 1), a cell membrane protein critical for cellular iron uptake, and disrupted its interaction with holo-transferrin. SMC-specific St3gal5 knockout exacerbated iron accumulation at lesion sites and significantly promoted AAA development in mice, whereas GM3 supplementation suppressed lipid peroxidation, reduced iron deposition in aortic vascular SMCs, and markedly decreased AAA incidence. CONCLUSIONS: Together, these results suggest that GM3 dysregulation promotes ferroptosis of vascular SMCs in AAA. Furthermore, GM3 may constitute a new therapeutic target for AAA.

Lipidomics reveals the dynamics of lipid profile altered by omega-3 polyunsaturated fatty acid supplementation in healthy people.

Glycerophospholipids (GPs) and sphingolipids (SPs) are important lipid components in the body and play biological functions. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) are important nutrients, and their supplements are commonly used for preventing some diseases. However, the effect of n-3 PUFAs on the human glycerophospholipidome and sphingolipidome is unclear. We used targeted lipidomics to study the GP and SP profile of healthy individuals after supplementation with n-3 PUFAs for 3, 7, 14 and 21 days. Fuzzy c-means clustering was used to cluster the lipid species into six classes reflecting different changed-content patterns after n-3 PUFA supplementation. Among the species with significantly changed content, lysophospholipids were the most sensitive; their content started to increase on day 3. The content of phosphatidylserines increased at a later stage. The content of most of the phosphatidylcholines and alkylphosphatidylcholines decreased on day 21. A correlation network analysis of lipid species suggested that some enzymes involved in the metabolism of lysophospholipids and phosphatidylserines were regulated by n-3 PUFAs. Levels of creatine kinase-MB (CK-MB), urea, glucose, triglycerides and total bilirubin were altered by n-3 PUFA at 21 days. Correlation analysis revealed that the level of CK-MB was negatively correlated with those of species in lysophosphatidic acid, lysophosphatidylcholine, lysophosphatidylethanolamine and phosphatidylserine classes, which were increased by n-3 PUFA supplementation. With the analysis in this work, we demonstrated the regular pattern of n-3 PUFAs on GP and SP metabolism, which provides a pharmacological basis for n-3 PUFAs for clinical application.

Omega-3 PUFA attenuate mice myocardial infarction injury by emerging a protective eicosanoid pattern.

Omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation is a recommended preventive approach against cardiovascular diseases, but its mechanism of protection against myocardial infarction (MI) injury is not fully understood. Eicosanoid metabolomics demonstrated an abnormal eicosanoid profile was in the plasma of mice receiving MI surgery. 19,20-EDP, 17,18-EEQ, 14,15-EET and 9,10-EpOME were decreased, and PGE2 was increased by the surgery. N-3 PUFA-rich diets feeding or transgene of Fat-1 shifted the eicosanoid profile to an n-3 PUFA dominant style and attenuated the myocardial infarction injury. Multiple logistic regression analysis suggested the degree of MI injury was related with an eicosanoid pattern, composed by eicosanoids derived from both n-3 and n-6 PUFA in the three enzymatic pathways. These results suggested the benefits of n-3 PUFA on MI was achieved synergistically.

Metabolic profiling of murine plasma reveals eicosapentaenoic acid metabolites protecting against endothelial activation and atherosclerosis.

BACKGROUND AND PURPOSE: Atherosclerosis results from a maladaptive inflammatory response initiated by the intramural retention of LDL in susceptible areas of the arterial vasculature. The ω-3 polyunsaturated fatty acids (ω-3) have protective effects in atherosclerosis; however, their molecular mechanism is still largely unknown. The present study used a metabolomic approach to reveal the atheroprotective metabolites of ω-3 and investigate the underlying mechanisms. EXPERIMENTAL APPROACH: We evaluated the development of atherosclerosis in LDL receptor-deficient mice (LDLR-/- ) fed a Western-type diet (WTD) plus ω-3 and also LDLR-/- and fat-1 transgenic (LDLR-/- -fat-1tg ) mice fed a WTD. The profiles of ω-3 in the plasma were screened by LC-MS/MS using unbiased systematic metabolomics analysis. We also studied the effect of metabolites of eicosapentaenoic acid (EPA) on endothelial activation in vitro. KEY RESULTS: The ω-3 diet and fat-1 transgene decreased monocyte infiltration, inhibited the expression of pro-inflammatory genes and significantly attenuated atherosclerotic plaque formation and enhanced plaque stability in LDLR-/- mice. The content of 18-hydroxy-eicosapentaenoic acid (18-HEPE) and 17,18-epoxy-eicosatetraenoic acid (17,18-EEQ), from the cytochrome P450 pathway of EPA, was significantly higher in plasma from both ω-3-treated LDLR-/- and LDLR-/- -fat-1tg mice as compared with WTD-fed LDLR-/- mice. In vitro in endothelial cells, 18-HEPE or 17,18-EEQ decreased inflammatory gene expression induced by TNFα via NF-κB signalling and thereby inhibited monocyte adhesion to endothelial cells. CONCLUSIONS AND IMPLICATIONS: EPA protected against the development of atherosclerosis in atheroprone mice via the metabolites 18-HEPE and/or 17,18-EEQ, which reduced endothelial activation. These compounds may have therapeutic implications in atherosclerosis. LINKED ARTICLES: This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.

Systematic metabolomic analysis of eicosanoids after omega-3 polyunsaturated fatty acid supplementation by a highly specific liquid chromatography-tandem mass spectrometry-based method.

Omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) have beneficial effects in many pathological processes, especially cardiovascular disease, and their protective eicosanoid metabolites are thought to play important roles. However, how ω-3 PUFAs affect the eicosanoid profile has not been elucidated comprehensively. Here, we systematically analyzed the eicosanoid metabolites induced by ω-3 PUFA supplementation. We developed an LC-MS/MS-based method covering 32 arachidonic acid (ARA) metabolites and 37 ω-3 PUFA-derived products. The limits of detection for eicosanoids were between 0.0625 and 1 pg and the detection specificity was optimized. We then quantified eicosanoids in mouse and human plasma and mouse aorta samples after ω-3 PUFA supplementation. Levels of EPA hydroxyl products, 4-HDoHE, 17,18-EEQ, 17,18-DiHETE, TXB2, and LXA4 were significantly changed in both mouse samples, and those of 2-series PGs, EDPs and DHA hydroxyl products were changed in aorta samples. Correlation network analysis of mouse plasma data revealed that some eicosanoids had higher connection degree or betweenness centrality score than others after ω-3 PUFA supplementation. Eicosanoids in human plasma were profiled across five time points after ω-3 PUFA supplementation. Fuzzy c-mean clustering algorithm suggested that the time curves of eicosanoid activity could be described with three kinetic patterns: sustained upregulation, short-term upregulation, and downregulation. This is the first systematic profiling of eicosanoids with ω-3 PUFA supplementation. The highly specific eicosanoid metabolomic and related data analysis methods would be powerful tools for comprehensive eicosanoid study.

Enhanced therapeutic efficacy of combined use of sorafenib and transcatheter arterial chemoembolization for treatment of advanced hepatocellular carcinoma.

OBJECTIVE: Clinical trials suggest that combining transcatheter arterial chemoembolization with sorafenib in patients with advanced hepatocellular carcinoma shows a superior safety and tolerability profile. Our study aimed to retrospectively analyze the utility and prognostic factors of this combined therapy in these patients. METHODS: Patients with advanced hepatocellular carcinoma, treated by transcatheter arterial chemoembolization and sorafenib subsequently, between February 2010 and September 2012 in our hospital, were retrospectively analyzed. After sorafenib treatment for 12 weeks, abdominal enhanced computed tomography or magnetic resonance imaging was used to evaluate short-term outcomes and clinical benefit rate. Overall survival and adverse events were recorded during follow-up. Univariate and multivariate analyses were used to identify relationships between baseline characteristics and overall survival. RESULTS: Fifty-one advanced hepatocellular carcinoma patients were included. Common adverse events for sorafenib were hand-foot skin reaction, alopecia, diarrhea, anorexia and fatigue. The clinical benefit rate was 64% and the median survival time was 7.5 months. Median survival of patients with and without portal vein tumor thrombi was 6.0 months and 10.3 months (P < 0.001), respectively. Median survival of patients with cholinesterase ≥5000 U/l and < 5000 U/l was 10.6 months and 6.1 months (P < 0.001), respectively. Multivariate analysis identified the presence of portal vein tumor thrombi and low cholinesterase level as independent negative predictors of survival. CONCLUSIONS: Combining sorafenib and transcatheter arterial chemoembolization was safe and effective for advanced hepatocellular carcinoma patients with extrahepatic spread but without portal vein tumor thrombi. Portal vein tumor thrombi and cholinesterase level are independent predictors of prognosis following this combined therapy.