Effect of biological sex on human circulating lipidome: An overview of the literature

Improving 10-year cardiovascular risk prediction in patients with type 2 diabetes with metabolomics

BACKGROUND

Existing cardiovascular risk prediction models still have room for improvement in patients with type 2 diabetes who represent a high-risk population. This study evaluated whether adding metabolomic biomarkers could enhance the 10-year prediction of major adverse cardiovascular events (MACE) in these patients.

METHODS

Data from 10,257 to 1,039 patients with type 2 diabetes from the UK Biobank (UKB) and the German ESTHER cohort, respectively, were used for model derivation, internal and external validation. A total of 249 metabolites were measured with nuclear magnetic resonance (NMR) spectroscopy. Sex-specific LASSO regression with bootstrapping identified significant metabolites. The enhanced model's predictive performance was evaluated using Harrell's C-index.

RESULTS

Seven metabolomic biomarkers were selected by LASSO regression for enhanced MACE risk prediction (three for both sexes, three male- and one female-specific metabolite(s)). Especially albumin and the omega-3-fatty-acids-to-total-fatty-acids-percentage among males and lactate among females improved the C-index. In internal validation with 30% of the UKB, adding the selected metabolites to the SCORE2-Diabetes model increased the C-index statistically significantly (P = 0.037) from 0.660 to 0.678 in the total sample. In external validation with ESTHER, the C-index increase was higher (+ 0.043) and remained statistically significant (P = 0.011).

CONCLUSIONS

Incorporating seven metabolomic biomarkers in the SCORE2-Diabetes model enhanced its ability to predict MACE in patients with type 2 diabetes. Given the latest cost reduction and standardization efforts, NMR metabolomics has the potential for translation into the clinical routine.

Identification of Disease-Relevant, Sex-Based Proteomic Differences in iPSC-Derived Vascular Smooth Muscle Cells

The prevalence of cardiovascular disease varies with sex, and the impact of intrinsic sex-based differences on vasculature is not well understood. Animal models can provide important insights into some aspects of human biology; however, not all discoveries in animal systems translate well to humans. To explore the impact of chromosomal sex on proteomic phenotypes, we used iPSC-derived vascular smooth muscle cells from healthy donors of both sexes to identify sex-based proteomic differences and their possible effects on cardiovascular pathophysiology. Our analysis confirmed that differentiated cells have a proteomic profile more similar to healthy primary aortic smooth muscle cells than iPSCs. We also identified sex-based differences in iPSC-derived vascular smooth muscle cells in pathways related to ATP binding, glycogen metabolic process, and cadherin binding as well as multiple proteins relevant to cardiovascular pathophysiology and disease. Additionally, we explored the role of autosomal and sex chromosomes in protein regulation, identifying that proteins on autosomal chromosomes also show sex-based regulation that may affect the protein expression of proteins from autosomal chromosomes. This work supports the biological relevance of iPSC-derived vascular smooth muscle cells as a model for disease, and further exploration of the pathways identified here can lead to the discovery of sex-specific pharmacological targets for cardiovascular disease.

The plasma lipidome varies with the severity of metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is closely associated with many aspects of disturbed metabolic health. MASLD encompasses a wide spectrum of liver diseases, ranging from isolated steatosis to metabolic dysfunction-associated steatohepatitis (MASH), up to fibrosis, cirrhosis, and ultimately hepatocellular carcinoma. Limited noninvasive diagnostic tools are currently available to distinguish the various stages of MASLD and as such liver biopsy remains the gold standard for MASLD diagnostics. We aimed to explore whether the plasma lipidome and its variations can serve as a biomarker for MASLD stages.

METHODS

We investigated the plasma lipidome of 7 MASLD-free subjects and 32 individuals with MASLD, of whom 11 had MASH based on biopsy scoring.

RESULTS

Compared with the MASLD-free subjects, individuals with MASLD had higher plasma concentrations of sphingolipids, glycerolipids, and glycerophospholipids. Only plasma concentrations of ceramide-1-phosphate C1P(d45:1) and phosphatidylcholine PC(O-36:3), PC(O-38:3), and PC(36:2) differed significantly between presence of MASH in individuals with MASLD. Of these lipids, the first three have a very low relative plasma abundance, thus only PC(36:2) might serve as a biomarker with higher plasma concentrations in MASLD individuals without MASH compared to those with MASH.

CONCLUSIONS

Plasma lipids hold promise as biomarkers of MASLD stages, whereas plasma PC(36:2) concentrations would be able to distinguish individuals with MASH from those with MASLD without MASH.

Lipids and apolipoproteins and the risk of vascular disease and mortality outcomes in women and men with type 2 diabetes in the ADVANCE study

AIM

Whether apolipoproteins (apolipoprotein A1, apolipoprotein B, apolipoprotein B/apolipoprotein A1 [ApoB/ApoA1] ratio) or very-low-density lipoprotein (VLDL) cholesterol are better risk predictors than established lipid risk markers, and whether there are sex differences, is uncertain, both in general populations and in patients with diabetes. The aim of this study was to assess the association between established risk markers, apolipoproteins and the risk of macro- and microvascular disease and death in a large study of women and men with diabetes and to assess the potential sex differences in the associations.

MATERIALS AND METHODS

Established lipid risk markers were studied in 11 140 individuals with type 2 diabetes from the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified-Release Controlled Evaluation (ADVANCE) trial, and apolipoproteins (A1, B, ApoB/ApoA1 ratio) and VLDL cholesterol from nuclear magnetic resonance (NMR) lipid analyses in biobanked samples from 3586 individuals included in the ADVANCE case-cohort study (ADVANCE CC). Primary outcomes were major macro- and microvascular events and death. Cox proportional hazards models adjusted for confounders were used to quantify the associations (hazard ratio [HR] and 95% confidence intervals [CIs]) between established lipid risk markers and apolipoproteins with study outcomes. To address potential effect modification by sex, we investigated the association between the lipid risk markers and outcomes in subgroup analyses by sex.

RESULTS

There was a lower risk of macrovascular complications for high-density lipoprotein (HDL) cholesterol (HR [95%CI] 0.88 [0.82-0.95]), a higher risk for total cholesterol (1.10 [1.04-1.17]), low-density lipoprotein (LDL) cholesterol (1.15 [1.08-1.22]), non-HDL cholesterol (1.13 [1.07-1.20]) and the total cholesterol/HDL ratio (1.20 [1.14-1.27]) but no significant associations with triglycerides from ADVANCE. There was a higher risk of macrovascular complications for the ApoB/ApoA1 ratio (1.13 [1.03-1.24]) from the ADVANCE CC. Only the ApoB/ApoA1 ratio (1.19 [1.06-1.34]), but none of the established lipid risk markers, was associated with a higher risk of microvascular complications. There were no statistically significant sex differences for any of the established lipid risk markers or apolipoproteins with any outcome. Using C-statistics and net reclassification improvement (NRI) did not detect significant improvement in predicting all outcomes by adding lipids or apolipoproteins to the models with confounding factors only.

CONCLUSIONS/INTERPRETATION

All established lipid risk markers, except triglycerides, were predictors of macrovascular complications, but not microvascular complications, in patients with type 2 diabetes. The ApoB/ApoA1 ratio was associated with major macro- and microvascular complications, but there was no evidence that apolipoproteins are better than established lipid risk markers in predicting cardiovascular complications in patients with type 2 diabetes.

LC-HRMS Lipidomic Fingerprints in Serbian Cohort of Schizophrenia Patients

Schizophrenia (SCH) is a major mental illness that causes impaired cognitive function and long-term disability, so the requirements for reliable biomarkers for early diagnosis and therapy of SCH are essential. The objective of this work was an untargeted lipidomic study of serum samples from a Serbian cohort including 30 schizophrenia (SCH) patients and 31 non-psychiatric control (C) individuals by applying liquid chromatography (LC) coupled with high-resolution mass spectrometry (HRMS) and chemometric analyses. Principal component analysis (PCA) of all samples indicated no clear separation between SCH and C groups but indicated clear gender separation in the C group. Multivariate statistical analyses (PCA and orthogonal partial least squares discriminant analysis (OPLS-DA)) of gender-differentiated SCH and C groups established forty-nine differential lipids in the differentiation of male SCH (SCH-M) patients and male controls (C-M), while sixty putative biomarkers were identified in the differentiation of female SCH patients (SCH-F) and female controls (C-F). Lipidomic study of gender-differentiated groups, between SCH-M and C-M and between SCH-F and C-F groups, confirmed that lipids metabolism was altered and the content of the majority of the most affected lipid classes, glycerophospholipids (GP), sphingolipids (SP), glycerolipids (GL) and fatty acids (FA), was decreased compared to controls. From differential lipid metabolites with higher content in both SCH-M and SCH-F patients groups compared to their non-psychiatric controls, there were four common lipid molecules: ceramides Cer 34:2, and Cer 34:1, lysophosphatidylcholine LPC 16:0 and triacylglycerol TG 48:2. Significant alteration of lipids metabolism confirmed the importance of metabolic pathways in the pathogenesis of schizophrenia.

Identification of Disease-relevant, Sex-based Proteomic Differences in iPSC-derived Vascular Smooth Muscle

The prevalence of cardiovascular disease varies with sex, and the impact of intrinsic sex-based differences on vasculature is not well understood. Animal models can provide important insight into some aspects of human biology, however not all discoveries in animal systems translate well to humans. To explore the impact of chromosomal sex on proteomic phenotypes, we used iPSC-derived vascular smooth muscle cells from healthy donors of both sexes to identify sex-based proteomic differences and their possible effects on cardiovascular pathophysiology. Our analysis confirmed that differentiated cells have a proteomic profile more similar to healthy primary aortic smooth muscle than iPSCs. We also identified sex-based differences in iPSC- derived vascular smooth muscle in pathways related to ATP binding, glycogen metabolic process, and cadherin binding as well as multiple proteins relevant to cardiovascular pathophysiology and disease. Additionally, we explored the role of autosomal and sex chromosomes in protein regulation, identifying that proteins on autosomal chromosomes also show sex-based regulation that may affect the protein expression of proteins from autosomal chromosomes. This work supports the biological relevance of iPSC-derived vascular smooth muscle cells as a model for disease, and further exploration of the pathways identified here can lead to the discovery of sex-specific pharmacological targets for cardiovascular disease.

Significance

In this work, we have differentiated 4 male and 4 female iPSC lines into vascular smooth muscle cells, giving us the ability to identify statistically-significant sex-specific proteomic markers that are relevant to cardiovascular disease risk (such as PCK2, MTOR, IGFBP2, PTGR2, and SULTE1).

Sex differences in lipidomic and bile acid plasma profiles in patients with and without coronary artery disease

BACKGROUND

Lipids, including phospholipids and bile acids, exert various signaling effects and are thought to contribute to the development of coronary artery disease (CAD). Here, we aimed to compare lipidomic and bile acid profiles in the blood of patients with and without CAD stratified by sex.

METHODS

From 2015 to 2022, 3,012 patients who underwent coronary angiography were recruited in the INTERCATH cohort. From the overall cohort, subgroups were defined using patient characteristics such as CAD vs. no CAD, 1st vs. 3rd tertile of LDL-c, and female vs. male sex. Hereafter, a matching algorithm based on age, BMI, hypertension status, diabetes mellitus status, smoking status, the Mediterranean diet score, and the intake of statins, triglycerides, HDL-c and hs-CRP in a 1:1 ratio was implemented. Lipidomic analyses of stored blood samples using the Lipidyzer platform (SCIEX) and bile acid analysis using liquid chromatography with tandem mass spectrometry (LC‒MS/MS) were carried out.

RESULTS

A total of 177 matched individuals were analyzed; the median ages were 73.5 years (25th and 75th percentile: 64.1, 78.2) and 71.9 years (65.7, 77.2) for females and males with CAD, respectively, and 67.6 years (58.3, 75.3) and 69.2 years (59.8, 76.8) for females and males without CAD, respectively. Further baseline characteristics, including cardiovascular risk factors, were balanced between the groups. Women with CAD had decreased levels of phosphatidylcholine and diacylglycerol, while no differences in bile acid profiles were detected in comparison to those of female patients without CAD. In contrast, in male patients with CAD, decreased concentrations of the secondary bile acid species glycolithocholic and lithocholic acid, as well as altered levels of specific lipids, were detected compared to those in males without CAD. Notably, male patients with low LDL-c and CAD had significantly greater concentrations of various phospholipid species, particularly plasmalogens, compared to those in high LDL-c subgroup.

CONCLUSIONS

We present hypothesis-generating data on sex-specific lipidomic patterns and bile acid profiles in CAD patients. The data suggest that altered lipid and bile acid composition might contribute to CAD development and/or progression, helping to understand the different disease trajectories of CAD in women and men.

REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT04936438 , Unique identifier: NCT04936438.

Associations between dietary fatty acids intake and abdominal aortic calcification: a national population-based study

BACKGROUND

Abdominal aortic calcification (AAC) is a crucial indicator of cardiovascular health. This study aims investigates the associations between dietary fatty acid intake and AAC.

METHODS

In this study, a cross-sectional assessment was performed on a group of 2,897 individuals aged 40 and above, utilizing data from the NHANES. The focus was on examining dietary consumption of various fatty acids, including Saturated (SFA), Monounsaturated (MUFA), Polyunsaturated (PUFA), as well as Omega-3 and Omega-6. The evaluation of AAC was done by applying the Kauppila AAC score to results obtained from dual-energy X-ray absorptiometry scans. For statistical analysis, weighted multivariate linear and logistic regression were employed, with adjustments for variables like gender, age, ethnicity, and overall health condition.

RESULTS

Participants with higher intake of SFA and PUFA showed a positive association with AAC score, while higher levels of dietary Omega-3 and Omega-6 fatty acids was connected with a negative correlation. Subgroup analyses indicated consistent associations across different sexes and age groups. The study found that an increase in SFA and PUFA intake correlated with an increase in AAC score, whereas Omega-3 and Omega-6 intake correlated with a decrease.

CONCLUSION

This study underscores the importance of dietary fatty acid composition in the prevalence of AAC and its potential implications for dietary guidelines and cardiovascular disease prevention strategies.

Sex differences in the genetic and molecular mechanisms of coronary artery disease

Sex differences in coronary artery disease (CAD) presentation, risk factors and prognosis have been widely studied. Similarly, studies on atherosclerosis have shown prominent sex differences in plaque biology. Our understanding of the underlying genetic and molecular mechanisms that drive these differences remains fragmented and largely understudied. Through reviewing genetic and epigenetic studies, we identified more than 40 sex-differential candidate genes (13 within known CAD loci) that may explain, at least in part, sex differences in vascular remodeling, lipid metabolism and endothelial dysfunction. Studies with transcriptomic and single-cell RNA sequencing data from atherosclerotic plaques highlight potential sex differences in smooth muscle cell and endothelial cell biology. Especially, phenotypic switching of smooth muscle cells seems to play a crucial role in female atherosclerosis. This matches the known sex differences in atherosclerotic phenotypes, with men being more prone to lipid-rich plaques, while women are more likely to develop fibrous plaques with endothelial dysfunction. To unravel the complex mechanisms that drive sex differences in CAD, increased statistical power and adjustments to study designs and analysis strategies are required. This entails increasing inclusion rates of women, performing well-defined sex-stratified analyses and the integration of multi-omics data.