Plasma Lipidomics Identifies Unique Lipid Signatures and Potential Biomarkers for Patients With Aortic Dissection

From big data to big insights: statistical and bioinformatic approaches for exploring the lipidome

The goal of lipidomic studies is to provide a broad characterization of cellular lipids present and changing in a sample of interest. Recent lipidomic research has significantly contributed to revealing the multifaceted roles that lipids play in fundamental cellular processes, including signaling, energy storage, and structural support. Furthermore, these findings have shed light on how lipids dynamically respond to various perturbations. Continued advancement in analytical techniques has also led to improved abilities to detect and identify novel lipid species, resulting in increasingly large datasets. Statistical analysis of these datasets can be challenging not only because of their vast size, but also because of the highly correlated data structure that exists due to many lipids belonging to the same metabolic or regulatory pathways. Interpretation of these lipidomic datasets is also hindered by a lack of current biological knowledge for the individual lipids. These limitations can therefore make lipidomic data analysis a daunting task. To address these difficulties and shed light on opportunities and also weaknesses in current tools, we have assembled this review. Here, we illustrate common statistical approaches for finding patterns in lipidomic datasets, including univariate hypothesis testing, unsupervised clustering, supervised classification modeling, and deep learning approaches. We then describe various bioinformatic tools often used to biologically contextualize results of interest. Overall, this review provides a framework for guiding lipidomic data analysis to promote a greater assessment of lipidomic results, while understanding potential advantages and weaknesses along the way.

7-Dehydrocholesterol dictates ferroptosis sensitivity

Ferroptosis, a form of regulated cell death that is driven by iron-dependent phospholipid peroxidation, has been implicated in multiple diseases, including cancer1-3, degenerative disorders4 and organ ischaemia-reperfusion injury (IRI)5,6. Here, using genome-wide CRISPR-Cas9 screening, we identified that the enzymes involved in distal cholesterol biosynthesis have pivotal yet opposing roles in regulating ferroptosis through dictating the level of 7-dehydrocholesterol (7-DHC)-an intermediate metabolite of distal cholesterol biosynthesis that is synthesized by sterol C5-desaturase (SC5D) and metabolized by 7-DHC reductase (DHCR7) for cholesterol synthesis. We found that the pathway components, including MSMO1, CYP51A1, EBP and SC5D, function as potential suppressors of ferroptosis, whereas DHCR7 functions as a pro-ferroptotic gene. Mechanistically, 7-DHC dictates ferroptosis surveillance by using the conjugated diene to exert its anti-phospholipid autoxidation function and shields plasma and mitochondria membranes from phospholipid autoxidation. Importantly, blocking the biosynthesis of endogenous 7-DHC by pharmacological targeting of EBP induces ferroptosis and inhibits tumour growth, whereas increasing the 7-DHC level by inhibiting DHCR7 effectively promotes cancer metastasis and attenuates the progression of kidney IRI, supporting a critical function of this axis in vivo. In conclusion, our data reveal a role of 7-DHC as a natural anti-ferroptotic metabolite and suggest that pharmacological manipulation of 7-DHC levels is a promising therapeutic strategy for cancer and IRI.

Metabolomic analysis reveals the metabolic disturbance in aortic dissection: Subtype difference and accurate diagnosis

BACKGROUND AND AIMS

Aortic dissection (AD), a severe clinical emergency with high mortality, is easily misdiagnosed as are other cardiovascular diseases. This study aimed at discovering plasma metabolic markers with the potential to diagnose AD and clarifying the metabolic differences between two subtypes of AD.

METHODS AND RESULTS

To facilitate the diagnosis of AD, we investigated the plasma metabolic profile by metabolomic approach. A total 482 human subjects were enrolled in the study: 80 patients with AD (50 with Stanford type A and 30 with Stanford type B), 198 coronary artery disease (CAD) patients, and 204 healthy individuals. Plasma samples were submitted to targeted metabolomic analysis. The partial least-squares discriminant analysis models were constructed to illustrate clear discrimination of AD patients with CAD patients and healthy control. Subsequently, the metabolites that were clinically relevant to the disturbances in AD were identified. Twenty metabolites induced the separation of AD patients and healthy control, 9 of which caused the separation of CAD patients and healthy control. There are 11 metabolites specifically down-regulated in AD group. Subgroup analysis showed that the levels of glycerol and uridine were dramatically lower in the plasma of patients with Stanford type A AD than those in the healthy control or Stanford type B AD groups.

CONCLUSION

This study characterized metabolomic profiles specifically associated with the pathogenesis and development of AD. The findings of this research may potentially lead to earlier diagnosis and treatment of AD.

Targeting metabolism in aortic aneurysm and dissection: from basic research to clinical applications

Aortic aneurysm and dissection (AAD) are a group of insidious and lethal cardiovascular diseases that characterized by seriously threatening the life and health of people, but lack effective nonsurgical interventions. Alterations in metabolites are increasingly recognized as universal features of AAD because metabolic abnormalities have been identified not only in arterial tissue but also in blood and vascular cells from both patients and animal models with this disease. Over the past few decades, studies have further supported this notion by linking AAD to various types of metabolites such as those derived from gut microbiota or involved in TCA cycle or lipid metabolism. Many of these altered metabolites may contribute to the pathogenesis of AAD. This review aims to illustrate the close association between body metabolism and the occurrence and development of AAD, as well as summarize the significance of metabolites correlated with the pathological process of AAD. This provides valuable insight for developing new therapeutic agents for AAD. Therefore, we present a brief overview of metabolism in AAD biology, including signaling pathways involved in these processes and current clinical studies targeting AAD metabolisms. It is necessary to understand the metabolic mechanisms underlying AAD to provides significant knowledge for AAD diagnosis and new therapeutics for treatment.

Effects of high-sugar, high-cholesterol, and high-fat diet on phospholipid profile of mouse tissues with a focus on the mechanism of plasmalogen synthesis

High-sugar diet (HSD), high-cholesterol diet (HCD), and high-fat diet (HFD) all modulate the levels of lipids. However, there is a lack of comparative data on the effects of different diets on phospholipids (PLs). Given their important role in physiology and disease, there has been an increasing focus on altered PLs in liver and brain disorders. This study aims to determine the effects of HSD, HCD, and HFD for 14-week feeding on the PL profile of the mouse liver and hippocampus. Quantitative analysis of 116 and 113 PL molecular species in liver and hippocampus tissues revealed that the HSD, HCD, and HFD significantly affected the PLs in liver and hippocampus, especially decreased the levels of plasmenylethanolamine (pPE) and phosphatidylethanolamine (PE). Overall, the impact of HFD on liver PLs was more significant, consistent with the morphological changes in the liver. Compared to HSD and HCD, HFD induced a significant decrease in PC (P-16:0/18:1) and an increase in LPE (18:0) and LPE (18:1) in liver. In the liver of mice fed with different diets, the expression of the key enzymes Gnpat, Agps in the pPE biosynthesis pathway and peroxisome-associated membrane proteins pex14p were decreased. In addition, all diets significantly reduced the expression of Gnpat, pex7p, and pex16p in hippocampus tissue. In conclusion, HSD, HCD, and HFD enhanced lipid accumulation in the liver, led to liver injury, significantly affected the liver and hippocampus PLs, and decreased the expression of genes related to plasmalogen synthesis in mouse liver and hippocampus, which caused severe plasmalogen reduction.

The plasma phospholipidome of the bottlenose dolphin (Tursiops truncatus) is modulated by both sex and developmental stage

Lipidomics represent a valid complementary tool to the biochemical analysis of plasma in humans. However, in cetaceans, these tools have been unexplored. Here, we evaluated how the plasma lipid composition of Tursiops truncatus is modulated by developmental stage and sex, aiming at a potential use of lipidomics in integrated strategies to monitor cetacean health. We characterized the fatty acid profile and detected a total of 26 fatty acids in T. truncatus plasma. The most abundant fatty acids were palmitic acid (C16:0), stearic acid (C18:0) and oleic acid (C18:1n-9). Interestingly, there are consistent differences between the fatty acid profile of mature female and mature male specimens. Phospholipidome analysis identified 320 different lipid species belonging to phosphatidylcholine (PC, 105 lipid species), lysophosphatidylcholine (42), phosphatidylethanolamine (PE, 67), lysophosphatidylethanolamine (18), phosphatidylglycerol (14), lysophosphatidylglycerol (8), phosphatidylinositol (14), lysophosphatidylinositol (2), phosphatidylserine (3), sphingomyelin (45) and ceramides (2) classes. The statistical analysis of the phospholipidome showed that its composition allows discriminating mature animals between sexes and mature males from immature males. Notably, discrimination between sexes is mainly determined by the contents of PE plasmalogens and lysophospholipids (LPC and LPE), while the differences between mature and immature male animals were mainly determined by the levels of PC lipids. This is the first time that a correlation between developmental stage and sex and the lipid composition of the plasma has been established in cetaceans. Being able to discern between age and sex-related changes is an encouraging step towards using these tools to also detect differences related to disease/dysfunction processes.

CircRNA MBOAT2 promotes intrahepatic cholangiocarcinoma progression and lipid metabolism reprogramming by stabilizing PTBP1 to facilitate FASN mRNA cytoplasmic export

The carcinogenic role of FASN by regulating lipid metabolism reprogramming has been well-established in multiple tumors. However, whether mechanisms during intrahepatic cholangiocarcinoma (ICC) progression, such as circRNAs, regulate FASN expression remains unknown. Here we demonstrate a lipid metabolism-related circRNA, circMBOAT2 (hsa_circ_0007334 in circBase), frequently upregulated in ICC tissues, and positively correlated with ICC malignant features. CircMBOAT2 knockdown inhibits the growth and metastasis of ICC cells. Mechanistically, circMBOAT2 combines with PTBP1 and protects PTBP1 from ubiquitin/proteasome-dependent degradation, impairing the function of PTBP1 to transfer FASN mRNA from the nucleus to the cytoplasm. Moreover, circMBOAT2 and FASN have the same effect on fatty acid profile, unsaturated fatty acids instead of saturated fatty acids are primarily regulated and associated with malignant behaviors of ICC cells. The levels of lipid peroxidation and ROS were significantly higher when FASN was knocked down and recovered when circMBOAT2 was overexpressed. Our results identified that circMBOAT2 was upregulated in ICC and promoted progression by stabilizing PTBP1 to facilitate FASN mRNA cytoplasmic export, which altered lipid metabolic profile and regulated redox homeostasis in ICC, suggesting that circMBOAT2 may serve as an available therapeutic target for ICC with active lipid metabolism.

Applying multi-omics techniques to the discovery of biomarkers for acute aortic dissection

Acute aortic dissection (AAD) is a cardiovascular disease that manifests suddenly and fatally. Due to the lack of specific early symptoms, many patients with AAD are often overlooked or misdiagnosed, which is undoubtedly catastrophic for patients. The particular pathogenic mechanism of AAD is yet unknown, which makes clinical pharmacological therapy extremely difficult. Therefore, it is necessary and crucial to find and employ unique biomarkers for Acute aortic dissection (AAD) as soon as possible in clinical practice and research. This will aid in the early detection of AAD and give clear guidelines for the creation of focused treatment agents. This goal has been made attainable over the past 20 years by the quick advancement of omics technologies and the development of high-throughput tissue specimen biomarker screening. The primary histology data support and add to one another to create a more thorough and three-dimensional picture of the disease. Based on the introduction of the main histology technologies, in this review, we summarize the current situation and most recent developments in the application of multi-omics technologies to AAD biomarker discovery and emphasize the significance of concentrating on integration concepts for integrating multi-omics data. In this context, we seek to offer fresh concepts and recommendations for fundamental investigation, perspective innovation, and therapeutic development in AAD.

Serum Oxylipin Profiles Identify Potential Biomarkers in Patients with Acute Aortic Dissection

Aortic dissection (AD) is a life-threatening cardiovascular disease with a dismal prognosis. Inflammation plays an important role in AD. Oxylipins are bioactive lipids involved in the modulation of inflammation and may be involved in the pathogenesis and progression of AD. This study aims to identify possible metabolites related to AD. A total of 10 type A Aortic dissection (TAAD) patients, 10 type B Aortic dissection (TBAD) patients and 10 healthy controls were included in this study. Over 100 oxylipin species were identified and quantified by liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis. Our investigation demonstrated substantial alterations in 91 oxylipins between AD and healthy individuals. Patients with TAAD had 89 entries accessible compared to healthy controls. According to orthogonal partial least squares discriminant analysis (OPLS-DA), fitness (R²X = 0.362 and R²Y = 0.807, p = 0.03) and predictability (Q² = 0.517, p = 0.005) are the validation parameters between the two groups. Using multivariate logistic regression, 13-HOTrE and 16(17)-EpDPE were the risk factors in the aortic patients group compared to healthy people (OR = 2.467, 95%CI:1.256–7.245, p = 0.035; OR = 0.015, 95%CI:0.0002–0.3240, p = 0.016, respectively). In KEGG enrichment of differential metabolites, the arachidonic acid metabolism pathway has the most metabolites involved. We established a diagnostic model in distinguishing between AD and healthy people. The AUC was 0.905. Oxylipins were significantly altered in AD patients, suggesting oxylipin profile is expected to exploit a novel, non-invasive, objective diagnosis for AD.

Genome-Wide Identification of Associations of Circulating Molecules With Spontaneous Coronary Artery Dissection and Aortic Aneurysm and Dissection

Circulating proteins play functional roles in various biological processes and disease pathogenesis. The aim of this study was to highlight circulating proteins associated with aortic aneurysm and dissection (AAD) and spontaneous coronary artery dissection (SCAD). We examined the associations of circulating molecule levels with SCAD by integrating data from a genome-wide association study (GWAS) of CanSCAD and 7 pQTL studies. Mendelian randomization (MR) analysis was applied to examine the associations between circulating molecule levels and AAD by using data from UK Biobank GWAS and pQTL studies. The SCAD-associated SNPs in 1q21.2 were strongly associated with circulating levels of extracellular matrix protein 1 (ECM1) and 25 other proteins (encoded by CTSS, CAT, CNDP1, KNG1, SLAMF7, TIE1, CXCL1, MBL2, ESD, CXCL16, CCL14, KCNE5, CST7, PSME1, GPC3, MAP2K4, SPOCK3, LRPPRC, CLEC4M, NOG, C1QTNF9, CX3CL1, SCP2D1, SERPINF2, and FN1). These proteins were enriched in biological processes such as regulation of peptidase activity and regulation of cellular protein metabolic processes. Proteins (FGF6, FGF9, HGF, BCL2L1, and VEGFA) involved in the Ras signaling pathway were identified to be related to AAD. In addition, SCAD- and AAD-associated SNPs were associated with cytokine and lipid levels. MR analysis showed that circulating ECM1, SPOCK3 and IL1b levels were associated with AAD. Circulating levels of low-density lipoprotein cholesterol and small very-low-density lipoprotein particles were strongly associated with AAD. The present study found associations between circulating proteins and lipids and SCAD and AAD. Circulating ECM1 and low-density lipoprotein cholesterol may play a role in the pathology of SCAD and AAD.

Metabolomic Profile Reveals That Ceramide Metabolic Disturbance Plays an Important Role in Thoracic Aortic Dissection

Aims

Thoracic aortic dissection (TAD) is a life-threatening disease with no effective drug therapy thus far. New therapeutic targets and indications for timely surgical intervention are urgently needed. Our aim is to investigate new pathological mechanisms and potential biomarkers of TAD through global metabolomic profiling of aortic aneurysm and dissection patients.

Methods and Results

We performed untargeted metabolomics to determine plasma metabolite concentrations in an aortic disease cohort, including 70 thoracic aortic aneurysm (TAA) and 70 TAD patients, as well as 70 healthy controls. Comparative analysis revealed that sphingolipid, especially its core metabolite C18-ceramide, was significantly distinguished in TAD patients but not in TAA patients, which was confirmed by subsequent quantitative analysis of C18-ceramide in a validation cohort. By analyzing our existing multiomics data in aortic tissue in a murine TAD model and TAD patients, we found that an enhanced ceramide de novo synthesis pathway in macrophages might contribute to the elevated ceramide. Inhibition of the ceramide de novo synthesis pathway by myriocin markedly alleviated BAPN-induced aortic inflammation and dissection in mice. In vitro studies demonstrated that exogenous C18-ceramide promoted macrophage inflammation and matrix metalloprotein (MMP) expression through the NLRP3-caspase 1 pathway. In contrast, inhibition of endogenous ceramide synthesis by myriocin attenuated lipopolysaccharide (LPS)-induced macrophage inflammation.

Conclusions

Our findings demonstrated that ceramide metabolism disturbance might play a vital role in TAD development by aggravating aortic inflammation through the NLRP3 pathway, possibly providing a new target for pharmacological therapy and a potential biomarker of TAD.