Lipidomic Analysis of Plasma from Healthy Men and Women Shows Phospholipid Class and Molecular Species Differences between Sexes

The bone marrow lipidomics of mice reveal sex-related differences

Osteoporosis is a common skeletal disorder characterized by an imbalance between bone resorption and formation, exhibiting a higher prevalence in women compared with men. While previous studies have primarily focused on genomics and genetics in osteoporosis susceptibility, there is a lack of systematic exploration of sex-specific differences in lipid levels in mouse bone marrow. Multiple reaction monitoring-based liquid chromatography-trandem mass spectrometry (LC-MS/MS) was used to quantify lipidomic profiles in bone marrow samples from three female mice and three male mice. The LC-MS/MS technique based on the multiple reaction monitoring method identified and quantified 184 lipids from 15 lipid classes. The contents of most lipids in the bone marrow cells of female mice were higher than those in male mice, including four polyunsaturated fatty acids, three phospholipids and four sphingolipids. Among all the lipid molecules, lactosylceramide (d18:0/16:0) showed the highest fold change in female mice, while its precursor lipid, glucosylceramide, was the most up-regulated in male mice. This study, focusing on bone marrow lipidomics, elucidates significant sexual dimorphism in lipid levels within bone marrow cells. It provides novel evidence supporting the higher prevalence of osteoporosis in women and enhances our understanding of the connection between sex-specific lipid levels and the risk of osteoporosis.

Sexual dimorphism in the context of nutrition and health

Diets and dietary constituents that we consume have a considerable impact on disease risk. Intriguingly these effects may be modulated to some extent by sex. Lack of female representation in nutritional studies as well as a lack of stratification by sex has and continues to limit our understanding of these sex × diet interactions. Here we provide an overview of the current and available literature describing how exposure to certain dietary patterns (Western-style diet, Mediterranean diet, vegetarian/vegan, ketogenic diet) and dietary constituents (dietary fibre, PUFA and plant bioactive) influences disease risk in a sex-specific manner. Interestingly, these sex differences appear to be highly disease-specific. The identification of such sex differences in response to diet stresses the importance of sex stratification in nutritional research.

Effects of Nutrition Education Program for the Japan Diet on Serum Phospholipid Fatty Acid Compositions in Patients with Dyslipidemia: Re-analysis of Data from a Previous Randomized Controlled Trial

AIM

We investigated changes in serum phospholipid fatty acid compositions with intake of the Japan Diet (JD) (higher consumption of fish, soybeans, vegetables, seaweed/mushrooms/konjak, and unrefined cereals with reduced consumption of animal fat, meat and poultry with fat, sweets and alcoholic drinks) recommended by the Japan Atherosclerosis Society.

METHODS

A randomized parallel controlled clinical trial on JD intake was conducted on Japanese patients with dyslipidemia. Nutrition education, based on the JD or partial JD (PJD) at baseline and at 3 months, was provided and the participants were followed up for 6 months. Fatty acids comprising serum phospholipids were measured in the JD (n=44) and PJD (n=44) groups.

RESULTS

Fatty acid intakes of C20:4, C20:5 and C22:6 increased in the JD group as compared with the PJD group. The percentages of serum phospholipid, C22:1 and C20:5 increased, while those of C18:1, C20:3(n-6) and C20:4(n-6) decreased in the JD as compared with the PJD group at 3 months. Changes in the phospholipid concentrations of C20:5, C22:5 and C22:6 reflected those intake volumes. Serum phospholipid C20:5 and C22:6 showed inverse correlations with C18:1, C18:2, and C20:3(n-6) at baseline and the changes at 3 and 6 months. In contrast, no correlation was observed between C20:4(n-6) and those n-3 fatty acids. The ratios of fatty acid concentrations, C16:1/C16:0 and C18:1/C18:0, decreased, but the ratio of C20:4(n-6)/C20:3(n-6) increased in the JD group.

CONCLUSION

Nutrition education on the JD changed serum phospholipid fatty acid profiles in favor to prevent against cardiovascular risk factors in patients with dyslipidemia.

Lipid remodeling of adipose tissue in metabolic health and disease

Adipose tissue is a dynamic and metabolically active organ that plays a crucial role in energy homeostasis and endocrine function. Recent advancements in lipidomics techniques have enabled the study of the complex lipid composition of adipose tissue and its role in metabolic disorders such as obesity, diabetes, and cardiovascular disease. In addition, adipose tissue lipidomics has emerged as a powerful tool for understanding the molecular mechanisms underlying these disorders and identifying bioactive lipid mediators and potential therapeutic targets. This review aims to summarize recent lipidomics studies that investigated the dynamic remodeling of adipose tissue lipids in response to specific physiological changes, pharmacological interventions, and pathological conditions. We discuss the molecular mechanisms of lipid remodeling in adipose tissue and explore the recent identification of bioactive lipid mediators generated in adipose tissue that regulate adipocytes and systemic metabolism. We propose that manipulating lipid-mediator metabolism could serve as a therapeutic approach for preventing or treating obesity-related metabolic diseases.

Hepatitis C Virus Infection Upregulates Plasma Phosphosphingolipids and Endocannabinoids and Downregulates Lysophosphoinositols

A mass spectrometry-based lipidomic investigation of 30 patients with chronic hepatitis C virus (HCV) infection and 30 age- and sex-matched healthy blood donor controls was undertaken. The clustering and complete separation of these two groups was found by both unsupervised and supervised multivariate data analyses. Three patients who had spontaneously cleared the virus and three who were successfully treated with direct-acting antiviral drugs remained within the HCV-positive metabotype, suggesting that the metabolic effects of HCV may be longer-lived. We identified 21 metabolites that were upregulated in plasma and 34 that were downregulated (p < 1 × 10^-16 to 0.0002). Eleven members of the endocannabinoidome were elevated, including anandamide and eight fatty acid amides (FAAs). These likely activated the cannabinoid receptor GPR55, which is a pivotal host factor for HCV replication. FAAH1, which catabolizes FAAs, reduced mRNA expression. Four phosphosphingolipids, d16:1, d18:1, d19:1 sphingosine 1-phosphate, and d18:0 sphinganine 1-phosphate, were increased, together with the mRNA expression for their synthetic enzyme SPHK1. Among the most profoundly downregulated plasma lipids were several lysophosphatidylinositols (LPIs) from 3- to 3000-fold. LPIs are required for the synthesis of phosphatidylinositol 4-phosphate (PI4P) pools that are required for HCV replication, and LPIs can also activate the GPR55 receptor. Our plasma lipidomic findings shed new light on the pathobiology of HCV infection and show that a subset of bioactive lipids that may contribute to liver pathology is altered by HCV infection.

Circulating cell-free DNA in health and disease - the relationship to health behaviours, ageing phenotypes and metabolomics

Circulating cell-free DNA (cf-DNA) has emerged as a promising biomarker of ageing, tissue damage and cellular stress. However, less is known about health behaviours, ageing phenotypes and metabolic processes that lead to elevated cf-DNA levels. We sought to analyse the relationship of circulating cf-DNA level to age, sex, smoking, physical activity, vegetable consumption, ageing phenotypes (physical functioning, the number of diseases, frailty) and an extensive panel of biomarkers including blood and urine metabolites and inflammatory markers in three human cohorts (N = 5385; 17-82 years). The relationships were assessed using correlation statistics, and linear and penalised regressions (the Lasso), also stratified by sex.cf-DNA levels were significantly higher in men than in women, and especially in middle-aged men and women who smoke, and in older more frail individuals. Correlation statistics of biomarker data showed that cf-DNA level was higher with elevated inflammation (C-reactive protein, interleukin-6), and higher levels of homocysteine, and proportion of red blood cells and lower levels of ascorbic acid. Inflammation (C-reactive protein, glycoprotein acetylation), amino acids (isoleucine, leucine, tyrosine), and ketogenesis (3-hydroxybutyrate) were included in the cf-DNA level-related biomarker profiles in at least two of the cohorts.In conclusion, circulating cf-DNA level is different by sex, and related to health behaviour, health decline and metabolic processes common in health and disease. These results can inform future studies where epidemiological and biological pathways of cf-DNA are to be analysed in details, and for studies evaluating cf-DNA as a potential clinical marker.

Plasma lipidomic profiles of kidney, breast and prostate cancer patients differ from healthy controls

Early detection of cancer is one of the unmet needs in clinical medicine. Peripheral blood analysis is a preferred method for efficient population screening, because blood collection is well embedded in clinical practice and minimally invasive for patients. Lipids are important biomolecules, and variations in lipid concentrations can reflect pathological disorders. Lipidomic profiling of human plasma by the coupling of ultrahigh-performance supercritical fluid chromatography and mass spectrometry is investigated with the aim to distinguish patients with breast, kidney, and prostate cancers from healthy controls. The mean sensitivity, specificity, and accuracy of the lipid profiling approach were 85%, 95%, and 92% for kidney cancer; 91%, 97%, and 94% for breast cancer; and 87%, 95%, and 92% for prostate cancer. No association of statistical models with tumor stage is observed. The statistically most significant lipid species for the differentiation of cancer types studied are CE 16:0, Cer 42:1, LPC 18:2, PC 36:2, PC 36:3, SM 32:1, and SM 41:1 These seven lipids represent a potential biomarker panel for kidney, breast, and prostate cancer screening, but a further verification step in a prospective study has to be performed to verify clinical utility.

Production of the infant formula ingredient 1,3-olein-2-palmitin in Arabidopsis thaliana seeds

In human milk fat, palmitic acid (16:0) is esterified to the middle (sn-2 or β) position on the glycerol backbone and oleic acid (18:1) predominantly to the outer positions, giving the triacylglycerol (TG) a distinctive stereoisomeric structure that is believed to assist nutrient absorption in the infant gut. However, the fat used in most infant formulas is derived from plants, which preferentially esterify 16:0 to the outer positions. We have previously showed that the metabolism of the model oilseed Arabidopsis thaliana can be engineered to incorporate 16:0 into the middle position of TG. However, the fatty acyl composition of Arabidopsis seed TG does not mimic human milk, which is rich in both 16:0 and 18:1 and is defined by the high abundance of the TG molecular species 1,3-olein-2-palmitin (OPO). Here we have constructed an Arabidopsis fatty acid biosynthesis 1-1 fatty acid desaturase 2 fatty acid elongase 1 mutant with around 20% 16:0 and 70% 18:1 in its seeds and we have engineered it to esterify more than 80% of the 16:0 to the middle position of TG, using heterologous expression of the human lysophosphatidic acid acyltransferase isoform AGPAT1, combined with suppression of LYSOPHOSPHATIDIC ACID ACYLTRANSFERASE 2 and PHOSPHATIDYLCHOLINE:DIACYLGLYCEROL CHOLINEPHOSPHOTRANSFERASE. Our data show that oilseeds can be engineered to produce TG that is rich in OPO, which is a structured fat ingredient used in infant formulas.