Wide-Targeted Semi-Quantitative Analysis of Acidic Glycosphingolipids in Cell Lines and Urine to Develop Potential Screening Biomarkers for Renal Cell Carcinoma.

Glycosphingolipids (GSLs), mainly located in the cell membrane, play various roles in cancer cell function. GSLs have potential as renal cell carcinoma (RCC) biomarkers; however, their analysis in body fluids is challenging because of the complexity of numerous glycans and ceramides. Therefore, we applied wide-targeted lipidomics using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with selected reaction monitoring (SRM) based on theoretical mass to perform a comprehensive measurement of GSLs and evaluate their potency as urinary biomarkers. In semi-quantitative lipidomics, 240 SRM transitions were set based on the reported/speculated structures. We verified the feasibility of measuring GSLs in cells and medium and found that disialosyl globopentaosylceramide (DSGb5 (d18:1/16:0)) increased GSL in the ACHN medium. LC-MS/MS analysis of urine samples from clear cell RCC (ccRCC) patients and healthy controls showed a significant increase in the peak intensity of urinary DSGb5 (d18:1/16:0) in the ccRCC group compared with that in the control group. Receiver operating characteristic analysis indicated that urinary DSGb5 could serve as a sensitive and specific marker for RCC screening, with an AUC of 0.89. This study demonstrated the possibility of urinary screening using DSGb5 (d18:1/16:0). In conclusion, urinary DSGb5 (d18:1/16:0) was a potential biomarker for cancer screening, which could contribute to the treatment of RCC patients.

Non-target ROIMCR LC-MS analysis of the disruptive effects of TBT over time on the lipidomics of Daphnia magna.

INTRODUCTION: This study has investigated the temporal disruptive effects of tributyltin (TBT) on lipid homeostasis in Daphnia magna. To achieve this, the study used Liquid Chromatography-Mass Spectrometry (LC-MS) analysis to analyze biological samples of Daphnia magna treated with TBT over time. The resulting data sets were multivariate and three-way, and were modeled using bilinear and trilinear non-negative factor decomposition chemometric methods. These methods allowed for the identification of specific patterns in the data and provided insight into the effects of TBT on lipid homeostasis in Daphnia magna. OBJECTIVES: Investigation of how are the changes in the lipid concentrations of Daphnia magna pools when they were exposed with TBT and over time using non-targeted LC-MS and advanced chemometric analysis. METHODS: The simultaneous analysis of LC-MS data sets of Daphnia magna samples under different experimental conditions (TBT dose and time) were analyzed using the ROIMCR method, which allows the resolution of the elution and mass spectra profiles of a large number of endogenous lipids. Changes obtained in the peak areas of the elution profiles of these lipids caused by the dose of TBT treatment and the time after its exposure are analyzed by principal component analysis, multivariate curve resolution-alternative least square, two-way ANOVA and ANOVA-simultaneous component analysis. RESULTS: 87 lipids were identified. Some of these lipids are proposed as Daphnia magna lipidomic biomarkers of the effects produced by the two considered factors (time and dose) and by their interaction. A reproducible multiplicative effect between these two factors is confirmed and the optimal approach to model this dataset resulted to be the application of the trilinear factor decomposition model. CONCLUSION: The proposed non-targeted LC-MS lipidomics approach resulted to be a powerful tool to investigate the effects of the two factors on the Daphnia magna lipidome using chemometric methods based on bilinear and trilinear factor decomposition models, according to the type of interaction between the design factors.

Investigation of the Mechanism of Action of Periploca forrestii Schltr. Extract on Adjuvant Collagen Rats Based on UPLC-Q-Orbitrap-HRMS Non-Targeted Lipidomics.

Periploca forrestii Schltr. (P. forrestii) is a classical medicinal plant and is commonly used in traditional medicine for the treatment of rheumatoid arthritis, soft tissue injuries, and traumatic injuries. The aim of this study was to evaluate the anti-arthritic effects of three fractions of P. forrestii alcoholic extracts (PAE), P. forrestii water extracts (PWE), and total flavonoids from P. forrestii (PTF) on Freund's complete adjuvant (FCA)-induced arthritis in rats, and to use a non-targeted lipidomic method to investigate the mechanism of action of the three fractions of P. forrestii in the treatment of rheumatoid arthritis. To assess the effectiveness of anti-rheumatoid arthritis, various indicators were measured, including joint swelling, histopathological changes in the joints, serum cytokines (tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin-6 (IL-6)), and the joint inflammatory substance prostaglandin E2 (PGE2). Finally, ultra-performance liquid chromatography-quadrupole-orbitrap-high-resolution mass spectrometry (UPLC-Q-Orbitrap-HRMS) was used to determine the non-targeted lipid histology of the collected rat serum and urine samples to investigate the possible mechanism of action. PWE, PAE, and PTF were all effective in treating FCA-induced rheumatoid arthritis. The administered groups all reduced joint swelling and lowered serum inflammatory factor levels in rats. In the screening of lipid metabolite differences between serum and urine of the rat model group and the normal group, a total of 52 different metabolites were screened, and the levels of lipid metabolites in PWE, PAE, and PTF were significantly higher than those in the normal group after administration. In addition, PWE, PAE, and PTF may have significant therapeutic effects on FCA-induced arthritis by modulating nicotinic acid, nicotinamide, and histidine metabolic pathways.

Diet Restriction Impact on High-Fat-Diet-Induced Obesity by Regulating Mitochondrial Cardiolipin Biosynthesis and Remodeling.

Diet restriction (DR) ameliorates obesity by regulating mitochondrial function. Cardiolipin (CL), a mitochondrial phospholipid, is closely associated with mitochondrial function. This study aimed to evaluate the anti-obesity effects of graded levels of DR based on mitochondrial CL levels in the liver. Obese mice were treated with 0%, 20%, 40%, and 60% reductions in the normal diet compared to normal animals (0 DR, 20 DR, 40 DR, and 60 DR groups, respectively). Biochemical and histopathological analyses were performed to evaluate the ameliorative effects of DR on obese mice. The altered profile of mitochondrial CL in the liver was explored using a targeted metabolomics strategy by ultra-high-pressure liquid chromatography MS/MS coupled with quadrupole time-of-flight mass spectrometry. Finally, gene expression associated with CL biosynthesis and remodeling was quantified. Tissue histopathology and biochemical index evaluations revealed significant improvements in the liver after DR, except for the 60 DR group. The variation in mitochondrial CL distribution and DR levels showed an inverted U-shape, and the CL content in the 40 DR group was the most upregulated. This result is consistent with the results of the target metabolomic analysis, which showed that 40 DR presented more variation. Furthermore, DR led to increased gene expression associated with CL biosynthesis and remodeling. This study provides new insights into the mitochondrial mechanisms underlying DR intervention in obesity.

Validation of a multiplexed and targeted lipidomics assay for accurate quantification of lipidomes.

A major challenge of lipidomics is to determine and quantify the precise content of complex lipidomes to the exact lipid molecular species. Often, multiple methods are needed to achieve sufficient lipidomic coverage to make these determinations. Multiplexed targeted assays offer a practical alternative to enable quantitative lipidomics amenable to quality control standards within a scalable platform. Herein, we developed a multiplexed normal phase liquid chromatography-hydrophilic interaction chromatography multiple reaction monitoring method that quantifies lipid molecular species across over 20 lipid classes spanning wide polarities in a single 20-min run. Analytical challenges such as in-source fragmentation, isomer separations, and concentration dynamics were addressed to ensure confidence in selectivity, quantification, and reproducibility. Utilizing multiple MS/MS product ions per lipid species not only improved the confidence of lipid identification but also enabled the determination of relative abundances of positional isomers in samples. Lipid class-based calibration curves were applied to interpolate lipid concentrations and guide sample dilution. Analytical validation was performed following FDA Bioanalytical Method Validation Guidance for Industry. We report repeatable and robust quantitation of 900 lipid species measured in NIST-SRM-1950 plasma, with over 700 lipids achieving inter-assay variability below 25%. To demonstrate proof of concept for biomarker discovery, we analyzed plasma from mice treated with a glucosylceramide synthase inhibitor, benzoxazole 1. We observed expected reductions in glucosylceramide levels in treated animals but, more notably, identified novel lipid biomarker candidates from the plasma lipidome. These data highlight the utility of this qualified lipidomic platform for enabling biological discovery.

Targeted lipidomics analysis of lysine 179 acetylation of ACSF2 in rat hepatic stellate cells.

Activation of hepatic stellate cells (HSCs) is generally recognized as a central driver of liver fibrosis. Metabolism of fatty acids (FA) plays a critical role in the activation of HSCs. Proteomics analysis on lysine acetylation of proteins in activated HSCs in our previous study indicated that acetylation of the lysine residues on ACSF2 is one of the most significantly upregulated sites in activated-HSCs and K179 is its important acetylation site. However, the role of acetylation at K179 of ACSF2 on activation of HSCs and free fatty acids (FFA) metabolism remains largely unknown. The reported study demonstrates that acetylation at K179 of ACSF2 promoted HSCs activation. The targeted lipidomic analysis indicated K179 acetylation of ACSF2 mainly affected long chain fatty acids (LCFA) metabolism, especially oleic acid, elaidic acid and palmitoleic acid. And the liquid chromatography mass spectrometry (LC-MS) analysis further demonstrated the formation of many long-chain acyl-CoAs were catalyzed by acetylation at K179 of ACSF2 including oleic acid, elaidic acid and palmitoleic acid. In conclusion, this study indicated that ACSF2 may be a potential therapeutic targets by regulating the metabolism of LCFA for liver fibrosis.

Screening of radiation gastrointestinal injury biomarkers in rat plasma by high-coverage targeted lipidomics.

INTRODUCTION: In the event of radiological accidents and cancer radiotherapies in the clinic, the gastrointestinal (GI) system is vulnerable to ionizing radiation and shows GI injury. Accessible biomarkers may provide means to predict, evaluate, and treat GI tissue damage. The current study investigated radiation GI injury biomarkers in rat plasma. MATERIAL AND METHODS: High-coverage targeted lipidomics was employed to profile lipidome perturbations at 72 h after 0, 1, 2, 3, 5, and 8 Gy (60Co γ-rays at 1 Gy/min) total-body irradiation in male rat jejunum. The results were correlated with previous plasma screening outcomes. RESULTS: In total, 93 differential metabolites and 28 linear dose-responsive metabolites were screened in the jejunum. Moreover, 52 lipid species with significant differences both in jejunum and plasma were obtained. Three lipid species with linear dose-response relationship both in jejunum and plasma were put forth, which exhibited good to excellent sensitivity and specificity in triaging different exposure levels. DISCUSSION: The linear dose-effect relationship of lipid metabolites in the jejunum and the triage performance of radiation GI injury biomarkers in plasma were studied for the first time. CONCLUSION: The present study can provide insights into expanded biomarkers of IR-mediated GI injury and minimally invasive assays for evaluation.

Differential lipidomics of HK-2 cells and exosomes under high glucose stimulation.

Abnormal cellular lipid metabolism has a very important role in the occurrence and progression of diabetic kidney disease (DKD). However, the lipid composition and differential expression by high glucose stimulation of renal tubular cells and their exosomes, which is a vital part of the development of DKD, are largely unknown. In this study, based on targeted lipid analysis by isotope labeling and tandem mass spectrometry, a total of 421 and 218 lipid species were quantified in HK-2 cells and exosomes, respectively. More importantly, results showed that GM3 d18:1/22:0, GM3 d18:1/16:0, GM3 d18:0/16:0, GM3 d18:1/22:1 were significantly increased, while LPE18:1, LPE, CL66:4 (16:1), BMP36:3, CL70:7 (16:1), CL74:8 (16:1) were significantly decreased in high glucose-stimulated HK-2 cells. Also, PG36:1, FFA22:5, PC38:3, SM d18:1/16:1, CE-16:1, CE-18:3, CE-20:5, and CE-22:6 were significantly increased, while GM3 d18:1/24:1, GM3 were significantly decreased in exosomes secreted by high glucose-stimulated HK-2 cells. Furthermore, TAG, PC, CL were decreased significantly in the exosomes comparing with the HK-2 cells, and LPA18:2, LPI22:5, PG32:2, FFA16:1, GM3 d18:1/18:1, GM3 d18:1/20:1, GM3 d18:0/20:0, PC40:6p, TAG52:1(18:1), TAG52:0(18:0), CE-20:5, CE-20:4, CE-22:6 were only found in exosomes. In addition, the expression of PI4P in HK-2 cells decreased under a high glucose state. These data may be useful to provide new targets for exploring the mechanisms of DKD.

Molecular Characterization of Plasma HDL, LDL, and VLDL Lipids Cargos from Atherosclerotic Patients with Advanced Carotid Lesions: A Preliminary Report.

Carotid atherosclerosis represents a relevant healthcare problem, since unstable plaques are responsible for approximately 15% of neurologic events, namely transient ischemic attack and stroke. Although statins treatment has proven effective in reducing LDL-cholesterol and the onset of acute clinical events, a residual risk may persist suggesting the need for the detection of reliable molecular markers useful for the identification of patients at higher risk regardless of optimal medical therapy. In this regard, several lines of evidence show a relationship among specific biologically active plasma lipids, atherosclerosis, and acute clinical events. We performed a Selected Reaction Monitoring-based High Performance Liquid Chromatography-tandem Mass Spectrometry (SRM-based HPLC-MS/MS) analysis on plasma HDL, LDL, and VLDL fractions purified, by isopycnic salt gradient ultracentrifugation, from twenty-eight patients undergoing carotid endarterectomy, having either a "hard" or a "soft" plaque, with the aim of characterizing the specific lipidomic patterns associated with features of carotid plaque instability. One hundred and thirty lipid species encompassing different lipid (sub)classes were monitored. Supervised multivariate analysis showed that lipids belonging to phosphatidylethanolamine (PE), sphingomyelin (SM), and diacylglycerol (DG) classes mostly contribute to discrimination within each lipoprotein fraction according to the plaque typology. Differential analysis evidenced a significant dysregulation of LDL PE (38:6), SM (32:1), and SM (32:2) between the two groups of patients (adj. p-value threshold = 0.05 and log2FC ≥ |0.58|). Using this approach, some LDL-associated markers of plaque vulnerability have been identified, in line with the current knowledge of the key roles of these phospholipids in lipoprotein metabolism and cardiovascular disease. This proof-of-concept study reports promising results, showing that lipoprotein lipidomics may present a valuable approach for identifying new biomarkers of potential clinical relevance.

Sex Differences of Cardiolipin in Tissue Distribution Based on Targeted Lipidomic Analysis by UHPLC-QTOF-MS/MS.

Cardiolipins (CLs) are involved in ATP production, mitochondria biogenesis, apoptosis and mitophagy. Their tissue distribution can provide insight into the function of mitochondria and related diseases. However, the reports on tissue distribution of CLs remain limited. In this research, CLs were identified from heart, liver, kidney, spleen, lung, skeletal muscle, and brain using ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS/MS). Then, the distribution and sex difference of CLs in seven tissues were compared by a targeted lipidomic approach. A total of 88 CLs were identified, of which 58, 51, 57, 58, 50, 61 and 52 CLs were found in heart, liver, kidney, spleen, lung, skeletal muscle, and brain, respectively. Compared with the distribution of CLs in heart, liver, kidney, and skeletal muscle, the CLs in spleen, lung, and brain showed significant differences. Moreover, the results indicated that there were sex differences of CLs in liver and kidney. A total of 16 CLs in liver tissue and 21 CLs in kidney tissue, with significant sex differences, were screened. Our findings in the targeted lipidomic analysis demonstrated that tissue distribution of CLs was essential in the dynamic states and sex differences of CLs, which might provide evidence for the mitochondrial-related mechanism under physiological and pathological conditions.

Targeted Phosphoinositides Analysis Using High-Performance Ion Chromatography-Coupled Selected Reaction Monitoring Mass Spectrometry.

Phosphoinositides are minor components of cell membranes, but play crucial roles in numerous signal transduction pathways. To obtain quantitative measures of phosphoinositides, sensitive, accurate, and comprehensive methods are needed. Here, we present a quantitative targeted ion chromatography-mass spectrometry-based workflow that separates phosphoinositide isomers and increases the quantitative accuracy of measured phosphoinositides. Besides testing different analytical characteristics such as extraction and separation efficiency, the reproducibility of the developed workflow was also investigated. The workflow was verified in resting and stimulated human platelets, fat cells, and rat hippocampal brain tissue, where the LOD and LOQ for phosphoinositides were at 312.5 and 625 fmol, respectively. The robustness of the workflow is shown with different applications that confirms its suitability to analyze multiple less-abundant phosphoinositides.

Screening of Lipids for Early Triage and Dose Estimation after Acute Radiation Exposure in Rat Plasma Based on Targeted Lipidomics Analysis.

Rapid early triage and dose estimation is vital for limited medical resource allocation and treatment of a large number of the wounded after radiological accidents. Lipidomics has been utilized to delineate biofluid lipid signatures after irradiation. Here, high-coverage targeted lipidomics was employed to screen radiosensitive lipids after 0, 1, 2, 3, 5, and 8 Gy total body irradiation at 4, 24, and 72 h postirradiation in rat plasma. Ultra-performance liquid chromatography-tandem mass spectrometry with a multiple reaction monitoring method was utilized. In total, 416 individual lipids from 18 major classes were quantified and those biomarkers altered in a dose-dependent manner constituted panel A-panel D. Receiver operator characteristic curve analysis using combined lipids showed good to excellent sensitivity and specificity in triaging different radiation exposure levels (area under curve = 0.814-1.000). The equations for dose estimation were established by stepwise regression analysis for three time points. A novel strategy for radiation early triage and dose estimation was first established and validated using panels of lipids. Our study suggests that it is feasible to acquire quantitative lipid biomarker panels using targeted lipidomics platforms for rapid, high-throughput triage, which can provide further insights in developing lipidomics strategies for radiation biodosimetry in humans.

Diacylglycerol lipase alpha in astrocytes is involved in maternal care and affective behaviors.

Genetic deletion of cannabinoid CB1 receptors or diacylglycerol lipase alpha (DAGLa), the main enzyme involved in the synthesis of the endocannabinoid (eCB) 2-arachidonoylglycerol (2-AG), produced profound phenotypes in animal models of depression-related behaviors. Furthermore, clinical studies have shown that antagonists of CB1 can increase the incidence and severity of major depressive episodes. However, the underlying pathomechanisms are largely unknown. In this study, we have focused on the possible involvement of astrocytes. Using the highly sensitive RNAscope technology, we show for the first time that a subpopulation of astrocytes in the adult mouse brain expresses Dagla, albeit at low levels. Targeted lipidomics revealed that astrocytic DAGLa only accounts for a minor percentage of the steady-state brain 2-AG levels and other arachidonic acid derived lipids like prostaglandins. Nevertheless, the deletion of Dagla in adult mouse astrocytes had profound behavioral consequences with significantly increased depressive-like behavioral responses and striking effects on maternal behavior, corresponding with increased levels of serum progesterone and estradiol. Our findings therefore indicate that lipids from the DAGLa metabolic axis in astrocytes play a key regulatory role in affective behaviors.

Plasma lipidomic profiles after a low and high glycemic load dietary pattern in a randomized controlled crossover feeding study.

BACKGROUND: Dietary patterns low in glycemic load are associated with reduced risk of cardiometabolic diseases. Improvements in serum lipid concentrations may play a role in these observed associations. OBJECTIVE: We investigated how dietary patterns differing in glycemic load affect clinical lipid panel measures and plasma lipidomics profiles. METHODS: In a crossover, controlled feeding study, 80 healthy participants (n = 40 men, n = 40 women), 18-45 y were randomized to receive low-glycemic load (LGL) or high glycemic load (HGL) diets for 28 days each with at least a 28-day washout period between controlled diets. Fasting plasma samples were collected at baseline and end of each diet period. Lipids on a clinical panel including total-, VLDL-, LDL-, and HDL-cholesterol and triglycerides were measured using an auto-analyzer. Lipidomics analysis using mass-spectrometry provided the concentrations of 863 species. Linear mixed models and lipid ontology enrichment analysis were implemented. RESULTS: Lipids from the clinical panel were not significantly different between diets. Univariate analysis showed that 67 species on the lipidomics panel, predominantly in the triacylglycerol class, were higher after the LGL diet compared to the HGL (FDR < 0.05). Three species with FA 17:0 were lower after LGL diet with enrichment analysis (FDR < 0.05). CONCLUSION: In the context of controlled eucaloric diets with similar macronutrient distribution, these results suggest that there are relative shifts in lipid species, but the overall pool does not change. Further studies are needed to better understand in which compartment the different lipid species are transported in blood, and how these shifts are related to health outcomes. This trial was registered at clinicaltrials.gov as NCT00622661.

Applications of mass spectrometry-based targeted and non-targeted lipidomics.

Recent advances in mass spectrometry have expanded our knowledge of lipids and lipid metabolic pathways involved in many (patho)physiological events. Targeted and non-targeted lipidomics are powerful analytical strategies with distinct features, and a combination of these two approaches is often employed to maximize the coverage of lipid species detected and quantified in complex biological matrices. This review briefly summarizes the applications of targeted and non-targeted lipidomics, mainly focusing on electrospray ionization-liquid chromatography-tandem mass spectrometry (ESI-LC-MS/MS), along with recent technical advances in the field. Current limitations and challenges in lipidomics and possible solutions are also discussed.

Comprehensive analyses of oxidized phospholipids using a measured MS/MS spectra library.

Oxidized phospholipids (OxPLs) are widely held to be associated with various diseases, such as arteriosclerosis, diabetes, and cancer. To characterize the structure-specific behavior of OxPLs and their physiological relevance, we developed a comprehensive analytical method by establishing a measured MS/MS spectra library of OxPLs. Biogenic OxPLs were prepared by the addition of specific oxidized fatty acids to cultured cells, where they were incorporated into cellular phospholipids, and untargeted lipidomics by LC-quadrupole/TOF-MS was applied to collect MS/MS spectra for the OxPLs. Based on the measured MS/MS spectra for about 400 molecular species of the biogenic OxPLs, we developed a broad-targeted lipidomics system using triple quadrupole MS. Separation precision of structural isomers was optimized by multiple reaction monitoring analysis and this system enabled us to detect OxPLs at levels as low as 10 fmol. When applied to biological samples, i.e., mouse peritoneal macrophages, this system enabled us to monitor a series of OxPLs endogenously produced in a 12/15-lipoxygenase-dependent manner. This advanced analytical method will be useful to elucidate the structure-specific behavior of OxPLs and their physiological relevance in vivo.

Dietary LA and sex effects on oxylipin profiles in rat kidney, liver, and serum differ from their effects on PUFAs.

A vast literature on fatty acids in mammals exists, but comparable compositional data on oxylipins is lacking. Weanling Sprague-Dawley rats were therefore provided control diets or diets with higher linoleic acid (LA) or with higher LA and α-linolenic acid (LA+ALA) for 6 weeks. Kidneys, livers, and serum were analyzed for oxylipins and fatty acids. The proportion of tissue oxylipins derived from LA was greater than the relative proportion of LA itself, whereas arachidonic acid (AA) oxylipins were overrepresented in serum. Higher dietary LA increased kidney LA and AA oxylipins, despite not altering LA or AA. In liver, both LA and AA and their oxylipins were higher, whereas in serum only LA oxylipins were higher with higher dietary LA. Higher LA resulted in a higher ratio of n-6/n-3 PUFA-derived oxylipins; adding ALA to the LA diet mitigated this and many, but not all, effects of the LA diet. Approximately 40% of oxylipins detected were influenced by sex and, unlike their PUFA precursors, most (>90%) of these were higher in males. These differences in dietary LA and sex on oxylipin and fatty acid profiles further our understanding of the effects of fatty acids and may have implications for dietary LA recommendations.

Plasma lipidomics reveals potential lipid markers of major depressive disorder.

Major depressive disorder (MDD) is a grave debilitating mental disease with a high incidence and severely impairs quality of life. Therefore, its physiopathological basis study and diagnostic biomarker discovery are extremely valuable. In this study, a non-targeted lipidomics strategy using ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was performed to reveal differential lipids between MDD (n = 60) and healthy controls (HCs, n = 60). Validation of changed lipid species was performed in an independent batch including 75 MDD and 52 HC using the same lipidomic method. Pronouncedly changed lipid species in MDD were discovered, which mainly were lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), 1-O-alkyl-2-acyl-PE (PE O), 1-O-alkyl-2-acyl-PC (PC O), sphingomyelin (SM), diacylglycerol (DG), and triacylglycerol (TG). Among these lipid species, LPC, LPE, PC, PE, PI, TG, etc. remarkably increased in MDD and showed pronounced positive relationships with depression severity, while 1-O-alkyl-2-acyl-PE and SM with odd summed carbon number significantly decreased in MDD and demonstrated negative relationships with depression severity. A combinational lipid panel including LPE 20:4, PC 34:1, PI 40:4, SM 39:1, 2, and TG 44:2 was defined as potential diagnostic biomarker with a good sensitivity and specificity for distinguishing MDD from HCs. Our study brings insights into lipid metabolism disorder in MDD and provides a specific potential biomarker for MDD diagnose.

Effects of fishing stress on fatty acid and amino acid composition and glycolipid metabolism in triploid rainbow trout.

Triploid Oncorhynchus mykiss is an important economic fish worldwide. Fishing stress can affect its growth and meat quality. This study first explored the effects of fishing stress on fatty acid and amino acid in triploid O. mykiss. Results showed fishing stress significantly reduced the content of docosadienoic acid, Gly, Arg, and DAA (P < 0.05). Targeted lipidomics analysis furthered suggested that some lipid molecules belonging to TG, DG, PC, Cer, ChE, and So were significantly up-regulated; while some lipid molecules belonging to Cer, LPE, LPC, PS, PC, and SM were significantly down-regulated, suggesting an accelerated glycolipid metabolism. Eventually, the glycolipid metabolism-related enzyme activity and gene expressions were examined, and the results indicated that O. mykiss was anti-oxidative stress by affecting relevant glycolipid metabolism signaling pathways and participating in cellular redox homeostasis. Findings of this study provide a theoretical foundation for further investigation into the mechanisms through which fishing stress affects O. mykiss.