Characterizing plasma phospholipid fatty acid profiles of polycystic ovary syndrome patients with and without insulin resistance using GC–MS and chemometrics approach

Genetic insights of blood lipid metabolites on polycystic ovary syndrome risk: a bidirectional two-sample Mendelian randomization study

Background

Pathologically, metabolic disorder plays a crucial role in polycystic ovarian syndrome (PCOS). However, there is no conclusive evidence lipid metabolite levels to PCOS risk.

Methods

In this study, genome-wide association study (GWAS) genetic data for 122 lipid metabolites were used to assign instrumental variables (IVs). PCOS GWAS were derived from a large-scale meta-analysis of 10,074 PCOS cases and 103,164 controls. An inverse variance weighted (IVW) analysis was the primary methodology used for Mendelian randomization (MR). For sensitivity analyses, Cochran Q test, MR-Egger intercept, MR-PRESSO, leave-one-out analysis,and Steiger test were performed. Furthermore, we conducted replication analysis, meta-analysis, and metabolic pathway analysis. Lastly, reverse MR analysis was used to determine whether the onset of PCOS affected lipid metabolites.

Results

This study detected the blood lipid metabolites and potential metabolic pathways that have a genetic association with PCOS onset. After IVW, sensitivity analyses, replication and meta-analysis, two pathogenic lipid metabolites of PCOS were finally identified: Hexadecanedioate (OR=1.85,95%CI=1.27-2.70, P=0.001) and Dihomo-linolenate (OR=2.45,95%CI=1.30-4.59, P=0.005). Besides, It was found that PCOS may be mediated by unsaturated fatty acid biosynthesis and primary bile acid biosynthesis metabolic pathways. Reverse MR analysis showed the causal association between PCOS and 2-tetradecenoyl carnitine at the genetic level (OR=1.025, 95% CI=1.003-1.048, P=0.026).

Conclusion

Genetic evidence suggests a causal relationship between hexadecanedioate and dihomo-linolenate and the risk of PCOS. These compounds could potentially serve as metabolic biomarkers for screening PCOS and selecting drug targets. The identification of these metabolic pathways is valuable in guiding the exploration of the pathological mechanisms of PCOS, although further studies are necessary for confirmation.

Metabolomics of male infertility

This review explores the use of metabolomics in male infertility. Metabolomics, an evolving omics technology that targets the products of cellular metabolism, is valuable for elucidating underlying pathophysiology of many disorders including male infertility. The identification of reliable biomarkers is essential for accurate diagnosis and for developing precision therapeutics for those afflicted by reproductive dysfunction. Unfortunately, despite significant progress to date, the intricate relationships between these metabolic pathways and male infertility remain elusive. It is clear, however, that additional research is required to more fully characterize the role of metabolomics in this disorder and in the potential development of targeted therapies for precision medicine.

The serine protease 2 gene regulates lipid metabolism through the LEP/ampkα1/SREBP1 pathway in bovine mammary epithelial cells

Molecular breeding has brought about significant transformations in the milk market and production system during the twenty-first century. The primary economic characteristic of dairy production pertains to milk fat content. Our previous transcriptome analyses revealed that serine protease 2 (PRSS2) is a candidate gene that could impact milk fat synthesis in bovine mammary epithelial cells (BMECs) of Chinese Holstein dairy cows. To elucidate the function of the PRSS2 gene in milk fat synthesis, we constructed vectors for PRSS2 overexpression and interference and assessed intracellular triglycerides (TGs), cholesterol (CHOL), and nonesterified fatty acid (NEFA) contents in BMECs. Fatty acid varieties and components were also quantified using gas chromatography‒mass spectrometry (GC‒MS) technology. The regulatory pathway mediated by PRSS2 was validated through qPCR, ELISA, and WB techniques. Based on our research findings, PRSS2 emerges as a pivotal gene that regulates the expression of associated genes, thereby making a substantial contribution to lipid metabolism via the leptin (LEP)/Adenylate-activated protein kinase, alpha 1 catalytic subunit (AMPKα1)/sterol regulatory element binding protein 1(SREBP1) pathway by inhibiting TGs and CHOL accumulation while potentially promoting NEFA synthesis in BMECs. Furthermore, the PRSS2 gene enhances intracellular medium- and long-chain fatty acid metabolism by modulating genes related to the LEP/AMPKα1/SREBP1 pathway, leading to increased contents of unsaturated fatty acids C17:1N7 and C22:4N6. This study provides a robust theoretical framework for further investigation into the underlying molecular mechanisms through which PRSS2 influences lipid metabolism in dairy cows.

Dihomo-γ-Linolenic Acid (20:3n-6)-Metabolism, Derivatives, and Potential Significance in Chronic Inflammation

Dihomo-γ-linolenic acid (DGLA) has emerged as a significant molecule differentiating healthy and inflamed tissues. Its position at a pivotal point of metabolic pathways leading to anti-inflammatory derivatives or via arachidonic acid (ARA) to pro-inflammatory lipid mediators makes this n-6 polyunsaturated fatty acid (PUFA) an intriguing research subject. The balance of ARA to DGLA is probably a critical factor affecting inflammatory processes in the body. The aim of this narrative review was to examine the potential roles of DGLA and related n-6 PUFAs in inflammatory conditions, such as obesity-associated disorders, rheumatoid arthritis, atopic dermatitis, asthma, cancers, and diseases of the gastrointestinal tract. DGLA can be produced by cultured fungi or be obtained via endogenous conversion from γ-linolenic acid (GLA)-rich vegetable oils. Several disease states are characterized by abnormally low DGLA levels in the body, while others can feature elevated levels. A defect in the activity of ∆6-desaturase and/or ∆5-desaturase may be one factor in the initiation and progression of these conditions. The potential of GLA and DGLA administrations as curative or ameliorating therapies in inflammatory conditions and malignancies appears modest at best. Manipulations with ∆6- and ∆5-desaturase inhibitors or combinations of long-chain PUFA supplements with n-3 PUFAs could provide a way to modify the body's DGLA and ARA production and the concentrations of their pro- and anti-inflammatory mediators. However, clinical data remain scarce and further well-designed studies should be actively promoted.

Intrafollicular fluid metabolic abnormalities in relation to ovarian hyperstimulation syndrome: Follicular fluid metabolomics via gas chromatography-mass spectrometry

INTRODUCTION

Ovarian hyperstimulation syndrome (OHSS) is the most serious iatrogenic complication of ovulation stimulation during assisted reproductive technology. The main objective of this study was to investigate intrafollicular fluid metabolic change profiles of OHSS in non-ovarian etiologic infertility women (CON) and polycystic ovarian syndrome patients (PCOS).

METHODS

87 infertile women were divided into four subgroups: CON-Norm (CON with normal ovarian response), CON-OHSS (CON with OHSS), PCOS-Norm (PCOS with normal ovarian response), and PCOS-OHSS (PCOS with OHSS). The intrafollicular fluid metabolic profiles were analyzed with gas chromatography-mass spectrometry. The multivariable-adjusted conditional logistic regression was applied to assess the association of metabolites with OHSS risk.

RESULTS

We identified 17 and 3 metabolites that related to OHSS risk in CON and PCOS, respectively. 13 OHSS risk-related metabolites in CON were unsaturated fatty acids, 8 of which were also the significantly altered metabolites between all PCOS and CON-Norm.

CONCLUSION

Our study may shed light on the role of intrafollicular fluid metabolic abnormalities in the pathophysiology of OHSS. The findings suggested that there might be some metabolic heterogeneities underlying the development of OHSS in CON and PCOS women and indicated possible shared etiological factors in the development of PCOS and OHSS.

Serum fatty acid profiles associated with metabolic risk in women with polycystic ovary syndrome

PURPOSE

Dyslipidemia is a feature of polycystic ovary syndrome (PCOS) that may augment metabolic disturbances. Serum fatty acids are important biomedical indicators of dyslipidemia. The aim of this study was to determine the distinct serum fatty acids in various PCOS subtypes and their association with metabolic risk in women with PCOS.

METHODS

Fatty acids in the serum of 202 women with PCOS were measured using gas chromatography-mass spectrometry. Fatty acids were compared between PCOS subtypes and correlated with glycemic parameters, adipokines, homocysteine, sex hormones, and sex hormone-binding globulin (SHBG).

RESULTS

The levels of total monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) in the reproductive subtype of PCOS were lower than those in the metabolic subtype. Docosahexaenoic acid, a PUFA, was associated with higher SHBG after correction for multiple comparisons. Eighteen species of fatty acids emerged as potential biomarkers associated with the metabolic risk factors measured, independent of body mass index (BMI). Among them, myristic acid (C14:0), palmitoleic acid (C16:1), oleic acid (C18:1n-9C), cis-vaccenic acid (C18:1n-7), and homo-gamma-linolenic acid (C20:3n-6) were the strongest lipid species that were consistently associated with metabolic risk factors, particularly insulin-related parameters in women with PCOS. As for adipokines, 16 fatty acids were positively associated with serum leptin. Among them, C16:1 and C20:3n-6were significantly associated with leptin levels.

CONCLUSION

Our data demonstrated that a distinct fatty acid profile comprising high C14:0, C16:1, C18:1n-9C, C18:1n-7, and C20:3n-6levels is associated with metabolic risk in women with PCOS, independent of BMI.

The association between serum fatty acids and pregnancy in PCOS women undergoing ovulation induction

BACKGROUND

Long-term dietary fat intake is thought to affect metabolism and pregnancy of polycystic ovary syndrome (PCOS) patients, and the type of fatty acids one consumes plays an important role. Previous studies mostly used questionnaires to analyze the type and proportion of fatty acids.

METHODS

This prospective study included 91 PCOS patients. Serum fatty acids were measured by the gas chromatograph-mass spectrometry method before ovulation induction. We compared the fatty acids between the pregnancy group and the nonpregnancy group and explored the influence of the fatty acids on live births and pregnancy loss.

RESULTS

Nervonic acid was lower in the pregnancy group than in the nonpregnancy group (0.25% vs. 0.30%, p = .017). The following trans-fatty acids were significantly lower in the pregnancy group than in the nonpregnancy group: trans-10-heptadecenoic acid, trans-vaccenic acid, trans-11-eicosenoic acid, and brassidic acid. The level of polyunsaturated fatty acids in the live birth group was significantly higher than the pregnancy loss group (16.95% vs. 15.10%, p = .039). Among individual PUFAs, the levels of linoleic acid (p = .043), docosapentaenoic acid (p = .024), alpha-linolenic acid (p = .042), and eicosapentaenoic acid (p = .035) were higher in the live birth group than in the pregnancy loss group. After adjusting for infertility duration, age, and body mass index, our findings suggested an inverse association between pregnancy and nervonic acid, trans-10-heptadecenoic acid, trans-vaccenic acid, trans-11-eicosenoic acid, and brassidic acid and pregnancy.

CONCLUSIONS

Our findings indicate that polyunsaturated fatty acids are associated with live birth in PCOS patients. Serum trans-fatty acids and nervonic acid might be risk factors for nonpregnancy. The mechanism of the influence of different fatty acids on pregnancy and live birth merits further exploration.

Novel Lipidomic Signature Associated With Metabolic Risk in Women With and Without Polycystic Ovary Syndrome

CONTEXT

Dyslipidemia is a feature of polycystic ovary syndrome (PCOS) and may augment metabolic dysfunction in this population.

OBJECTIVE

Using comprehensive lipidomic profiling and gold-standard metabolic measures, we examined whether distinct lipid biomarkers were associated with metabolic risk in women with and without PCOS.

METHODS

Using preexisting data and biobanked samples from 76 women (n = 42 with PCOS), we profiled > 700 lipid species by mass spectrometry. Lipids were compared between women with and without PCOS and correlated with direct measures of adiposity (dual x-ray absorptiometry and computed tomography) and insulin sensitivity (hyperinsulinemic-euglycemic clamp), as well as fasting insulin, HbA1c, and hormonal parameters (luteinizing and follicle-stimulating hormones; total and free testosterone; sex hormone-binding globulin [SHBG]; and free androgen index [FAI]). Multivariable linear regression was used with correction for multiple testing.

RESULTS

Despite finding no differences by PCOS status, lysophosphatidylinositol (LPI) species esterified with an 18:0 fatty acid were the strongest lipid species associated with all the metabolic risk factors measured in women with and without PCOS. Across the cohort, higher concentrations of LPI(18:0) and lower concentrations of lipids containing docosahexaenoic acid (DHA, 22:6) n-3 polyunsaturated fatty acids were associated with higher adiposity, insulin resistance, fasting insulin, HbA1c and FAI, and lower SHBG.

CONCLUSION

Our data indicate that a distinct lipidomic signature comprising high LPI(18:0) and low DHA-containing lipids are associated with key metabolic risk factors that cluster in PCOS, independent of PCOS status. Prospective studies are needed to corroborate these findings in larger cohorts of women with varying PCOS phenotypes.

Quantitative analysis of n-3 polyunsaturated fatty acids and their metabolites by chemical isotope labeling coupled with liquid chromatography - mass spectrometry

n-3 polyunsaturated fatty acids (PUFAs) and their metabolites play the crucial role in a wide range of physiologic and pathologic processes, including cardiovascular, neurodegenerative diseases, and inflammation-associated disorders. However, the quantitative analysis of n-3 PUFAs and their metabolites, oxylipins, is obstructed by high structural similarity, poor ionization efficiency and low abundance. In this study, a sensitive method was developed to quantify 28 n-3 PUFAs/oxylipins using chemical isotope labeling coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Standards labeled with cholamine-d₉ were used as one-to-one internal standards to achieve accurate quantification. The cholamine-d₀-derivatized biological samples were mixed with cholamine d₉-labeled standards for LC-MS/MS with multiple reaction monitoring. After cholamine derivatization, both MS sensitivity and chromatographic performance of n-3 PUFAs/oxylipins were substantially improved. Furthermore, the relationship between retention time and substituent position of regioisomers, and their fragmentation patterns were investigated, which may facilitate the identification of unknown oxylipins. Additionally, the developed method was applied to quantify the target n-3 PUFAs/oxylipins in serum and brain tissue from fish oil-supplemented mice, which exhibited its great potential and practicability. Collectively, this sensitive and reliable method may facilitate the elucidation of the roles of n-3 PUFAs/oxylipins in the physiological and pathological processes.

Metabolomic Profiling of Poor Ovarian Response Identifies Potential Predictive Biomarkers

OBJECTIVE

To characterize the serum metabolomic profile and its role in the prediction of poor ovarian response (POR).

PATIENTS

Twenty-five women with normal ovarian reserve (24-33 years, antral follicle count [AFC] ≥5, anti-Müllerian hormone [AMH] ≥1.2 ng/ml) as the control group and another twenty-five women with POR (19-35 years, AFC <5, AMH < 1.2 ng/ml) as the study group were collected in our study. The serum levels of the women in both groups were determined from their whole blood by untargeted liquid chromatography-mass spectrometry (LC-MS). Multivariate statistical analysis and cell signal pathways analysis were used to reveal the results.

RESULTS

A total of 538 different metabolites were finally identified in the two groups. Tetracosanoic acid, 2-arachidonoylglycerol, lidocaine, cortexolone, prostaglandin H2,1-naphthylamine, 5-hydroxymethyl-2-furancarboxaldehyde, 2,4-dinitrophenol, and D-erythrulose1-phosphate in POR were significantly different from control as were most important metabolites in support vector machines (p <0.05). Metabolomic profiling, together with support vector machines and pathway analysis found that the nicotinate and nicotinamide metabolism pathway, including L-aspartic acid, 6-hydroxynicotinate, maleic acid, and succinic acid semialdehyde, was identified to have significant differences in POR women compared to control women, which may be associated with ovarian reserve.

CONCLUSION

This study indicated that LC-MS-based untargeted metabolomics analysis of serum provided biological markers for women with POR. The nicotinate and nicotinamide metabolism pathway may offer new insight into the complementary prediction and therapeutic potential of POR. The functional associations of these metabolites need further investigation.

Oxidation of fish oil exacerbates alcoholic liver disease by enhancing intestinal dysbiosis in mice

The role of n-3 polyunsaturated fatty acids (PUFAs) in alcoholic liver disease (ALD) has been controversial. N-3 PUFA oxidation in animal feeding stuffs was rarely concerned, likely contributing to inconsistent outcomes. Here, we report the impacts of oxidized fish oil (OFO) on ALD in C57BL/6 mice. Alcohol exposure increased plasma aminotransferase levels and hepatic inflammation. These deleterious effects were ameliorated by unoxidized FO but exacerbated by OFO. Sequencing analysis showed the accentuated intestinal dysbiosis and the increased proportion of Proteobacteria in OFO-fed mice. Intestinal sterilization by antibiotics completely abolished OFO-aggravated liver injury. Additionally, alcohol exposure leads to the greater increase in plasma endotoxin and decrease in intestinal tight junction protein expressions in OFO-fed mice. Stabilization of intestinal barrier by obeticholic acid markedly blunted OFO-aggravated liver injury in alcohol-fed mice. These results demonstrate that OFO exacerbates alcoholic liver injury through enhancing intestinal dysbiosis, barrier dysfunction, and hepatic inflammation mediated by gut-derived endotoxin.

Feng et al. show that oxidized fish oil exacerbates alcoholic liver injury in mice by enhancing intestinal dysbiosis, barrier dysfunction, and hepatic inflammation that is mediated by gut-derived endotoxin. This study suggests that n-3 polyunsaturated fatty acids enriched in fish oil should be kept from oxidation to exert their health benefits.

The C18:3n6/C22:4n6 ratio is a good lipid marker of chronic kidney disease (CKD) progression

Background

Chronic kidney disease (CKD) is a major challenge for public health due to increased risk of cardiovascular diseases (CVD) and premature death. The aim of this study was to determine the clinical picture of FA and the course of the pathophysiological mechanisms of CKD.

Methods

The study involved 149 patients with CKD and a control group including 43 people. Fatty acid profiles were investigated using gas chromatography. A total of 30 fatty acids and their derivatives were identified and quantified. The omega3, omega6, SFA, MUFA, and PUFA fatty acid contents were calculated. The correlation matrix was obtained for parameters relating to patients with CKD vs. FA, taking patients’ sex into consideration. The index C18:3n6/C22:4n6 was calculated according to the length of the treatment. Statistica 12.0 software (Tulsa, Oklahoma, USA) was used for the statistical analyses.

Results

The results showed decreased levels of total PUFA and increased concentrations of MUFA, including the activation of the palmitic and oleic acid pathway. An increase in the levels of n-6 9C22: 4n6 family fatty acids in all the patients and a reduction in the n-3 family (EPA, DHA) were observed. C18:3n6 was negatively correlated and C22:4n6 was positively correlated with the duration of the treatment. The index C18:3n6/C22:4n6 was defined as a new marker in the progression of the disease. Moreover, the index C18:3n6/ C22:4n6 was drastically decreased in later period. Nervonic acid was higher in the CKD group. In the group of men with CKD, there was a negative correlation between the excretion of K+, anthropometric measurements, and the levels of EPA and DHA.

Conclusions

The course of inflammation in CKD occurs through the decrease in PUFA and the synthesis of MUFA. The dominating cascade of changes is the elongation of GLA-C18:3n6 into DGLA-C20:3n6 and AA-C20:4n6. As CKD progresses, along with worsening anthropometrical parameters and increased secretion of potassium, the activity of Ʌ6-desaturase decreases, reducing the synthesis of EPA and DHA. The synthesis of AdA-C22:4n6 increases and the ratio C18:3n6/C22:4n6 drastically decreases after 5 years. This parameter can be used to diagnose disease progression.

Gas chromatography-mass spectrometry-based analytical strategies for fatty acid analysis in biological samples

Fatty acids play critical roles in biological systems. Imbalances in fatty acids are related to a variety of diseases, which makes the measurement of fatty acids in biological samples important. Many analytical strategies have been developed to investigate fatty acids in various biological samples. Due to the structural diversity of fatty acids, many factors need to be considered when developing analytical methods including extraction methods, derivatization methods, column selections, and internal standard selections. This review focused on gas chromatography-mass spectrometry (GC-MS)-based methods. We reviewed several commonly used fatty acid extraction approaches, including liquid-liquid extraction and solid-phase microextraction. Moreover, both acid and base derivatization methods and other specially designed methods were comprehensively reviewed, and their strengths and limitations were discussed. Having good separation efficiency is essential to building an accurate and reliable GC-MS platform for fatty acid analysis. We reviewed the separation performance of different columns and discussed the application of multidimensional GC for improving separations. The selection of internal standards was also discussed. In the final section, we introduced several biomedical studies that measured fatty acid levels in different sample matrices and provided hints on the relationships between fatty acid imbalances and diseases.

Current Progress of Lipid Analysis in Metabolic Diseases by Mass Spectrometry Methods

BACKGROUND

Obesity, insulin resistance, diabetes, and metabolic syndrome are associated with lipid alterations, and they affect the risk of long-term cardiovascular disease. A reliable analytical instrument to detect changes in the composition or structures of lipids and the tools allowing to connect changes in a specific group of lipids with a specific disease and its progress, is constantly lacking. Lipidomics is a new field of medicine based on the research and identification of lipids and lipid metabolites present in human organism. The primary aim of lipidomics is to search for new biomarkers of different diseases, mainly civilization diseases.

OBJECTIVE

We aimed to review studies reporting the application of mass spectrometry for lipid analysis in metabolic diseases.

METHOD

Following an extensive search of peer-reviewed articles on the mass spectrometry analysis of lipids the literature has been discussed in this review article.

RESULTS

The lipid group contains around 1.7 million species; they are totally different, in terms of the length of aliphatic chain, amount of rings, additional functional groups. Some of them are so complex that their complex analyses are a challenge for analysts. Their qualitative and quantitative analysis of is based mainly on mass spectrometry.

CONCLUSION

Mass spectrometry techniques are excellent tools for lipid profiling in complex biological samples and the combination with multivariate statistical analysis enables the identification of potential diagnostic biomarkers.

Comparison of Fatty Acid Profiles in a Group of Female Patients with Chronic Kidney Diseases (CKD) and Metabolic Syndrome (MetS)⁻Similar Trends of Changes, Different Pathophysiology

Fatty acid (FA) profiles in the plasma of patients with metabolic syndrome and chronic kidney disease (CKD) seem to be identical despite their different etiology (dietary mistakes vs. cachexia). The aim of this study was to compare both profiles and to highlight the differences that could influence the improvement of the treatment of patients in both groups. The study involved 73 women, including 24 patients with chronic kidney disease treated with haemodialysis, 19 patients with metabolic syndrome (MetS), and 30 healthy women in the control group. A total of 35 fatty acids and derivatives were identified and quantified by gas chromatography. Intensified elongation processes from acid C10:0 to C16:0 were noted in both groups (more intense in MetS), as well as an increased synthesis of arachidonic acid (C20:4n6), which was more intense in CKD. Significant correlations of oleic acid (C18:1n9), gamma linoleic acid (C18:3n6), and docosatetraenoate acid (C22:4n6) with parameters of CKD patients were observed. In the MetS group, auxiliary metabolic pathways of oleic acid were activated, which simultaneously inhibited the synthesis of eicosapentanoic acid (EPA) and docosahexaenoic acid (DHA) from alpha lipoic acid (ALA). On the other hand, in the group of female patients with CKD, the synthesis of EPA and DHA was intensified. Activation of the synthesis of oleic acid (C18: 1n9 ct) and trans-vaccinic acid (C18:1) is a protective mechanism in kidney diseases and especially in MetS due to the increased concentration of saturated fatty acid (SFA) in plasma. The cause of the increased amount of all FAs in plasma in the CKD group, especially in the case of palmitic (C16:0) and derivatives stearic (C18:0) acids, may be the decomposition of adipose tissue and the progressing devastation of the organism, whereas, in the MetS group, dietary intake seems to be the main reason for the increase in SFA. Moreover, in MetS, auxiliary metabolic pathways are activated for oleic acid, which cause the simultaneous inhibition of EPA and DHA synthesis from ALA, whereas, in the CKD group, we observe an increased synthesis of EPA and DHA. The higher increase of nervonic acid (C24:1) in CKD suggests a higher degree of demyelination and loss of axons.

Alterations of Sphingolipid Metabolism in Different Types of Polycystic Ovary Syndrome

The roles of sphingolipids in polycystic ovary syndrome (PCOS) are still unknown. This study aimed to investigate the sphingolipid characteristics for different types of PCOS using liquid chromatography-mass spectrometry (LC-MS). A total of 107 women with PCOS and 37 healthy women as normal controls were studied. PCOS patients were further classified into non-obesity with insulin resistance (IR) (NOIR), obesity with IR (OIR), and non-obesity and non-IR (NIR) subgroups. A total of 87 serum sphingolipids, including 9 sphingosines, 3 sphinganines, 1 sphingosine-1-phosphate (S1P), 19 ceramides (Cers), 1 ceramide-1-phosphate, 44 sphingomyelins (SMs), 4 hexosylceramides, and 6 lactosylceramides (LacCers) were analyzed using an improved sphingolipidomic approach based on LC-MS. Notable elevations in the levels of S1P, Cer, and SM were observed in PCOS patients when compared with healthy women, and SM species with long saturated acyl chains showed potential as novel biomarkers of PCOS. In addition, the level of LacCer was only elevated in NIR, and there was almost no change in NOIR and OIR. This study is the first to report the comprehensive sphingolipidomic profiling of different subgroups of PCOS with or without IR or obesity and suggests that serum sphingolipids might be useful as diagnostic biomarkers for different types of PCOS.

Decrease in the Level of Nervonic Acid and Increased Gamma Linolenic Acid in the Plasma of Women with Polycystic Ovary Syndrome after a Three-month Low-glycaemic Index and Caloric Reduction Diet

The aetiology of polycystic ovary syndrome (PCOS) remains uncertain and thus dedicated studies are still of much importance. Patients in this group are at high risk for metabolic syndrome, diabetes and ischemic heart disease. Our goal was to use a dietary intervention, facilitating the regression of the disease, through the observation of lipid and hormonal profiles, carbohydrate metabolic parameters and metabolomics of plasma fatty acids. There were 39 Caucasian women with PCOS aged 26.76 ±5.08 that qualified for this study. Fatty acid profiles were investigated using gas chromatography. The results of plasma fatty acids were compared with the initial results and the control group. A three-month caloric reduction diet with low glycemic index (GI) reduces the level of nervonic acid and is a great alternative in PCOS therapy. The introduction of rapeseed oil and olive oil to the lowered GI reduction diet caused the increase in the ratio of average length chain fatty acids (C10:0, C14:0) and the enhancement of synthesis pathways for pentadecanoic acid (C15:0) and gamma-linolenic acid (GLA, C18:3n-6), but did not inhibit the synthesis of the derivatives of arachidic acid (C20:0). Additionally, a decrease in the level of nervonic acid (C24:1) was observed. Biochemical analysis of blood showed the improvement of plasma lipid fractions, but a significant reduction of androgen levels was not observed. A reduction diet with lowered GI lead to many positive effects in the improvement of the biochemical parameters of women with PCOS. It should be continued for a prolonged period of time, until the synthesis pathways for inflammatory factors are silenced.

Identification of Potential Biomarkers for Urine Metabolomics of Polycystic Ovary Syndrome Based on Gas Chromatography-Mass Spectrometry

Background:

Polycystic ovary syndrome (PCOS) is a complex endocrine and metabolic disorder, and it's diagnosis is difficult. The aim of this study was to investigate the metabolic profiles of PCOS patients by analyzing urine samples and identify useful biomarkers for diagnosis of PCOS.

Methods:

This study was carried out in the Department of Obstetrics and Gynecology of the Maternal and Child Health Hospital of Hunan Province from December 2014 to July 2016. In this study, the urine samples of 21 women with PCOS and 16 healthy controls were assessed through gas chromatography-mass spectrometry to investigate the urine metabolite characteristics of PCOS and identify useful biomarkers for the diagnosis of this disorder. The Student's t-test and rank sum test were applied to validate the statistical significance of the between the two groups.

Results:

In total, 35 urine metabolites were found to be significantly different between the PCOS patients and the controls. In particular, a significant increase in the levels of lactose (10.01 [0,13.99] mmol/mol creatinine vs. 2.35 [0.16, 3.26] mmol/mol creatinine, P = 0.042), stearic acid (2.35 [1.47, 3.14] mmol/mol creatinine vs. 0.05 [0, 0.14] mmol/mol creatinine, P < 0.001), and palmitic acid (2.13 [1.07, 2.79] mmol/mol creatinine vs. 0 [0, 0] mmol/mol creatinine, P < 0.001) and a decrease in the levels of succinic acid (0 [0, 0] mmol/mol creatinine vs. 38.94 [4.16, 51.30] mmol/mol creatinine, P < 0.001) were found in the PCOS patients compared with the controls. It was possible to cluster the PCOS patients and the healthy controls into two distinct regions based on a principal component analysis model. Of the differentially expressed metabolites, four compounds, including stearic acid, palmitic acid, benzoylglycine, and threonine, were selected as potential biomarkers.

Conclusions:

This study offers new insight into the pathogenesis of PCOS, and the discriminating urine metabolites may provide a prospect for the diagnosis of PCOS.

Metabolic pathways of oleic and palmitic acid are intensified in PCOS patients with normal androgen levels

CONTEXT

The aetiology and pathogenesis polycystic ovary syndrome (PCOS) remain uncertain and thus the relative studies are still crucial.

OBJECTIVE

Our aim was to analyse the fatty acids profiles of the main phospholipids species in serum from women with PCOS classified into phenotypes, and to diagnose women more susceptible to the occurrence of inflammatory state.

DESIGN

PCOS screening tests were performed in The Clinic of Gynecology and Urogynecology of Pomeranian Medical University in the 2014-2015 years.

SETTING

The study are designed for general community and a primary care or referral center.

PATIENTS

39 patients with PCOS, diagnosed according to Rotterdam's criteria, and 14 healthy women, as a control group, participated in this study. Fatty acid profiles were investigated using gas chromatography. A total of 36 fatty acids and their derivatives were identified and quantified.

MAIN OUTCOME MEASURE

Changes in fatty acids profile in plasma from women with PCOS phenotypes are not identical.

RESULTS

The analyses showed lowered level of total SFA, increase in the concentration of caprylic acid and the activation of palmitic and oleic acids pathways. The level of nervonic acid was several times higher than in the control group, and the levels of behenic and tricosanoic acids were reduced.

CONCLUSIONS

In both phenotypes the alternative metabolic pathways of oleic acid were activated, but they were more pronounced in women with proper level of androgens. Gamma-linolenic acid (C18:3n6) can be a factor protecting hyperandrogenic women.

Omega-3 polyunsaturated fatty acids ameliorate ethanol-induced adipose hyperlipolysis: A mechanism for hepatoprotective effect against alcoholic liver disease

Alcohol exposure induces adipose hyperlipolysis and causes excess fatty acid influx into the liver, leading to alcoholic steatosis. The impacts of omega-3 polyunsaturated fatty acids (n-3 PUFA) on ethanol-induced fatty liver are well documented. However, the role of n-3 PUFA in ethanol-induced adipose lipolysis has not been sufficiently addressed. In this study, the fat-1 transgenic mice that synthesizes endogenous n-3 from n-6 PUFA and their wild type littermates with an exogenous n-3 PUFA enriched diet were subjected to a chronic ethanol feeding plus a single binge as model to induce liver injury with adipose lipolysis. Additionally, the differentiated adipocytes from 3T3-L1 cells were treated with docosahexaenoic acid or eicosapentaenoic acid for mechanism studies. Our results demonstrated that endogenous and exogenous n-3 PUFA enrichment ameliorates ethanol-stimulated adipose lipolysis by increasing PDE3B activity and reducing cAMP accumulation in adipocyte, which was associated with activation of GPR120 and regulation of Ca²⁺/CaMKKβ/AMPK signaling, resultantly blocking fatty acid trafficking from adipose tissue to the liver, which contributing to ameliorating ethanol-induced adipose dysfunction and liver injury. Our findings identify that endogenous and exogenous n-3 PUFA enrichment ameliorated alcoholic liver injury by activation of GPR120 to suppress ethanol-stimulated adipose lipolysis, which provides the new insight to the hepatoprotective effect of n-3 PUFA against alcoholic liver disease.

Endogenous n-3 Fatty Acids Alleviate Carbon-Tetrachloride-Induced Acute Liver Injury in Fat-1 Transgenic Mice

n-3 polyunsaturated fatty acids (PUFAs) are beneficial for numerous models of liver diseases. The probable protective effects of n-3 PUFA against carbon-tetrachloride- (CCl₄-) induced acute liver injury were evaluated in a fat-1 transgenic mouse that synthesizes endogenous n-3 from n-6 PUFA. Fat-1 mice and their WT littermates were fed a modified AIN93 diet containing 10% corn oil and were injected intraperitoneally with a single dose of CCl₄ or vehicle. CCl₄ challenge caused severe liver injury in WT mice, as indicated by serum parameters and histopathological changes, which were remarkably ameliorated in fat-1 mice. Endogenous n-3 PUFA decreased the elevation of oxidative stress induced by CCl₄ challenge, which might be attributed to the activation of Nrf2/keap1 pathway. Additionally, endogenous n-3 PUFA reduces hepatocyte apoptosis via suppressing MAPK pathway. These findings indicate that n-3 PUFA has potent protective effects against acute liver injury induced by CCl₄ in mice, suggesting that n-3 PUFA can be used for the prevention and treatment of liver injury.

Dietary α-linolenic acid-rich flaxseed oil prevents against alcoholic hepatic steatosis via ameliorating lipid homeostasis at adipose tissue-liver axis in mice

Low levels of n-3 polyunsaturated fatty acids (PUFAs) in serum and liver tissue biopsies are the common characteristics in patients with alcoholic liver disease. The α-linolenic acid (ALA) is a plant-derived n-3 PUFA and is rich in flaxseed oil. However, the impact of ALA on alcoholic fatty liver is largely unknown. In this study, we assessed the potential protective effects of ALA-rich flaxseed oil (FO) on ethanol-induced hepatic steatosis and observed that dietary FO supplementation effectively attenuated the ethanol-induced hepatic lipid accumulation in mice. Ethanol exposure stimulated adipose lipolysis but reduced fatty acid/lipid uptake, which were normalized by FO. Our investigations into the corresponding mechanisms demonstrated that the ameliorating effect of FO might be associated with the lower endoplasmic reticulum stress and normalized lipid metabolism in adipose tissue. In the liver, alcohol exposure stimulated hepatic fatty acid uptake and triglyceride synthesis, which were attenuated by FO. Additionally, dietary FO upregulated plasma adiponectin concentration, hepatic adiponectin receptor 2 expression, and the activation of hepatic adenosine monophosphate-activated protein kinase. Collectively, dietary FO protects against alcoholic hepatic steatosis by improving lipid homeostasis at the adipose tissue-liver axis, suggesting that dietary ALA-rich flaxseed oil might be a promising approach for prevention of alcoholic fatty liver.

A potential tool for diagnosis of male infertility: Plasma metabolomics based on GC-MS

Male infertility has become an important public health problem worldwide. Nowadays the diagnosis of male infertility frequently depends on the results of semen quality or requires more invasive surgical intervention. Therefore, it is necessary to develop a novel approach for early diagnosis of male infertility. According to the presence or absence of normal sexual function, the male infertility is classified into two phenotypes, erectile dysfunction (ED) and semen abnormalities (SA). The aim of this study was to investigate the GC-MS plasma profiles of infertile male having erectile dysfunction (ED) and having semen abnormalities (SA) and discover the potential biomarkers. The plasma samples from healthy controls (HC) (n=61) and infertility patients with ED (n=26) or with SA (n=44) were analyzed by gas chromatography-mass spectrometry (GC-MS) for discrimination and screening potential biomarkers. The partial least squares-discriminant analysis (PLS-DA) was performed on GC-MS dataset. The results showed that HC could be discriminated from infertile cases having SA (AUC=86.96%, sensitivity=78.69%, specificity=84.09%, accuracy=80.95%) and infertile cases having ED (AUC=94.33%, sensitivity=80.33%, specificity=100%, accuracy=87.36%). Some potential biomarkers were successfully discovered by two commonly used variable selection methods, variable importance on projection (VIP) and original coefficients of PLS-DA (β). 1,5-Anhydro-sorbitol and α-hydroxyisovaleric acid were identified as the potential biomarkers for distinguishing HC from the male infertility patients. Meanwhile, lactate, glutamate and cholesterol were the found to be the important variables to distinguish between patients with erectile dysfunction from those with semen abnormalities. The plasma metabolomics may be developed as a novel approach for fast, noninvasive, and acceptable diagnosis and characterization of male infertility.

Abnormalities in Plasma Phospholipid Fatty Acid Profiles of Patients with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. In the present study, we aimed to profile the possible changes in plasma phospholipid fatty acid composition of HCC patients, and to identify the fatty acid biomarkers that could distinguish HCC patients from healthy controls. A total of 37 plasma samples from healthy controls and HCC patients were collected and their phospholipid fatty acid profiles were characterized by gas chromatography-mass spectrometry followed by multivariate statistical analysis. Twenty-five fatty acids were identified and quantified, their proportions varied greatly between two groups, suggesting each group has its own fatty acid pattern. Orthogonal partial least squares discriminant analysis in terms of fatty acid profiles showed that HCC patients could be clearly distinguished from healthy controls. More importantly, linoleic acid (18:2n-6), oleic acid (18:1n-9), arachidonic acid (20:4n-6) and palmitic acid (16:0) were identified as the potential fatty acid biomarkers of HCC patients. Additionally, to further identify the major cause of the abnormality of plasma fatty acid profile, fatty acid distributions of cancerous tissue and its surrounding tissue from 42 HCC patients were also examined. Due to have similar variation trend of major fatty acid biomarkers, linoleic acid (18:2n-6), oleic acid (18:1n-9), abnormalities in plasma phospholipid fatty acid profiles of HCC patients may be mainly attributed to the alternation of intrinsic fatty acid metabolism caused by cancer per se, but not to the differences in dietary factors.

Mitochondrial Citrate Transporter-dependent Metabolic Signature in the 22q11.2 Deletion Syndrome

The congenital disorder 22q11.2 deletion syndrome (22qDS), characterized by a hemizygous deletion of 1.5-3 Mb on chromosome 22 at locus 11.2, is the most common microdeletion disorder (estimated prevalence of 1 in 4000) and the second risk factor for schizophrenia. Nine of ∼30 genes involved in 22qDS have the potential of disrupting mitochondrial metabolism (COMT, UFD1L, DGCR8, MRPL40, PRODH, SLC25A1, TXNRD2, T10, and ZDHHC8). Deficits in bioenergetics during early postnatal brain development could set the basis for a disrupted neuronal metabolism or synaptic signaling, partly explaining the higher incidence in developmental and behavioral deficits in these individuals. Here, we investigated whether mitochondrial outcomes and metabolites from 22qDS children segregated with the altered dosage of one or several of these mitochondrial genes contributing to 22qDS etiology and/or morbidity. Plasma metabolomics, lymphocytic mitochondrial outcomes, and epigenetics (histone H3 Lys-4 trimethylation and 5-methylcytosine) were evaluated in samples from 11 22qDS children and 13 age- and sex-matched neurotypically developing controls. Metabolite differences between 22qDS children and controls reflected a shift from oxidative phosphorylation to glycolysis (higher lactate/pyruvate ratios) accompanied by an increase in reductive carboxylation of α-ketoglutarate (increased concentrations of 2-hydroxyglutaric acid, cholesterol, and fatty acids). Altered metabolism in 22qDS reflected a critical role for the haploinsufficiency of the mitochondrial citrate transporter SLC25A1, further enhanced by HIF-1α, MYC, and metabolite controls. This comprehensive profiling served to clarify the biochemistry of this disease underlying its broad, complex phenotype.