Lysophosphatidylcholine, oxidized low-density lipoprotein and cardiovascular disease in Korean hemodialysis patients: analysis at 5 years of follow-up

Probiotic therapy modulates the brain-gut-liver microbiota axis in a mouse model of traumatic brain injury

The interplay between gut microbiota and host health is crucial for maintaining the overall health of the body and brain, and it is even more crucial how changes in the bacterial profile can influence the aftermath of traumatic brain injury (TBI). We studied the effects of probiotic treatment after TBI to identify potential changes in hepatic lipid species relevant to brain function. Bioinformatic analysis of the gut microbiota indicated a significant increase in the Firmicutes/Bacteroidetes ratio in the probiotic-treated TBI group compared to sham and untreated TBI groups. Although strong correlations between gut bacteria and hepatic lipids were found in sham mice, TBI disrupted these links, and probiotic treatment did not fully restore them. Probiotic treatment influenced systemic glucose metabolism, suggesting altered metabolic regulation. Behavioral tests confirmed memory improvement in probiotic-treated TBI mice. While TBI reduced hippocampal mRNA expression of CaMKII and CREB, probiotics reversed these effects yet did not alter BDNF mRNA levels. Elevated pro-inflammatory markers TNF-α and IL1-β in TBI mice were not significantly affected by probiotic treatment, pointing to different mechanisms underlying the probiotic benefits. In summary, our study suggests that TBI induces dysbiosis, alters hepatic lipid profiles, and preemptive administration of Lactobacillus helveticus and Bifidobacterium longum probiotics can counter neuroplasticity deficits and memory impairment. Altogether, these findings highlight the potential of probiotics for attenuating TBI's detrimental cognitive and metabolic effects through gut microbiome modulation and hepatic lipidomic alteration, laying the groundwork for probiotics as a potential TBI therapy.

Metabolome and microbiome analyses reveal the efficacy of Shen-Fu formula in treating heart failure

Improvement of strategies to treat heart failure (HF) has been a longstanding global goal and challenge. Shen-Fu formula (SF), as a classic herbal preparation, has demonstrated efficacy in treating HF in clinical settings. However, further understanding of the therapeutic mechanisms of SF is required. In this study, metabolomics and 16S rDNA sequencing were used to analyze the effects of SF on metabolic profiling and gut microbiota in HF rats. After 4 weeks of SF treatment, the cardiac function of HF rats showed improvement, with a significant increase in ejection fraction and fractional shortening, as well as a significant decrease in left ventricular volume and mass. Metabolomics study revealed that SF regulates the levels of substances related to energy metabolism, primarily involving lysophosphatidylcholines and polyunsaturated fatty acids. In addition, we found that SF regulates the structure of the microbial community in HF rats and modulates the balance between probiotic and pathogenic bacteria. Furthermore, the SF combination exhibited a superior effect that was better than the use of each herb separately. These results demonstrate the potential of SF therapy in the management of HF and highlight the role of SF in regulating fatty acid metabolism and gut microbiome during HF.

Abdominal obesity in youth: the associations of plasma Lysophophatidylcholine concentrations with insulin resistance

BACKGROUD

This study aimed to explore the associations of lysophosphatidylcholines (LPCs) with insulin resistance (IR) and abdominal obesity among children and adolescents.

METHODS

A cross-sectional study was conducted on 612 young individuals, aged 7 to 18 years in Tianjin City, China. LC-MS metabolomic analysis was used to measure LPCs levels. The Homeostasis Model Assessment was used to estimate IR. Waist circumference measurements were used to assess abdominal obesity. Logistic regression models were employed to explore the relationships between LPCs and IR and abdominal obesity. Mediation analyses were performed to analyze whether LPCs affected IR through abdominal obesity.

RESULTS

Compared to their counterparts, five specific LPCs were significantly different in youth with IR. The levels of LPC 24:0 and 26:0 were significantly associated with IR after adjustment. Both decreased levels of LPC 24:0 and 26:0 associated with the increased risks of IR (OR: 0.64, 95%CI: 0.38-0.95; OR: 0.66, 95%CI: 0.40-1.00), and the ORs for abdominal obesity were 0.68 (95%CI: 0.38-1.00) and 0.51 (95%CI: 0.28-0.90), respectively. Mediation analysis indicated that abdominal obesity mediated the association between LPC 26:0 and IR, with a total effect (c) of -0.109 (P < 0.05), a direct effect (c') of -0.055 (P > 0.05), and an indirect effect through obesity (a × b) path with "a" of -0.125 (P < 0.05) and "b" of 0.426 (P < 0.05).

CONCLUSION

Overall findings suggest that decreased levels of LPC 24:0 and 26:0 were associated with increased risks of IR and abdominal obesity. Importantly, addressing abdominal obesity may mediate the impact of IR driven by LPC 26:0.

Phospholipid-derived lysophospholipids in (patho)physiology

Phospholipids (PL) are major components of cellular membranes and changes in PL metabolism have been associated with the pathogenesis of numerous diseases. Lysophosphatidylcholine (LPC) in particular, is a comparably abundant component of oxidatively damaged tissues. LPC originates from the cleavage of phosphatidylcholine (PC) by phospholipase A2 or the reaction of lipids with reactive oxygen species (ROS) such as HOCl. Another explanation of increased LPC concentration is the decreased re-acylation of LPC into PC. While there are also several other lysophospholipids, LPC is the most abundant lysophospholipid in mammals and will therefore be the focus of this review. LPC is involved in many physiological processes. It induces the migration of lymphocytes, fostering the production of pro-inflammatory compounds by inducing oxidative stress. LPC also "signals" via G protein-coupled and Toll-like receptors and has been implicated in the development of different diseases. However, LPCs are not purely "bad": this is reflected by the fact that the concentration and fatty acyl composition of LPC varies under different conditions, in plasma of healthy and diseased individuals, in tissues and different tumors. Targeting LPC and lipid metabolism and restoring homeostasis might be a potential therapeutic method for inflammation-related diseases.

Altered myocardial lipid regulation in junctophilin-2-associated familial cardiomyopathies

Myocardial lipid metabolism is critical to normal heart function, whereas altered lipid regulation has been linked to cardiac diseases including cardiomyopathies. Genetic variants in the JPH2 gene can cause hypertrophic cardiomyopathy (HCM) and, in some cases, dilated cardiomyopathy (DCM). In this study, we tested the hypothesis that JPH2 variants identified in patients with HCM and DCM, respectively, cause distinct alterations in myocardial lipid profiles. Echocardiography revealed clinically significant cardiac dysfunction in both knock-in mouse models of cardiomyopathy. Unbiased myocardial lipidomic analysis demonstrated significantly reduced levels of total unsaturated fatty acids, ceramides, and various phospholipids in both mice with HCM and DCM, suggesting a common metabolic alteration in both models. On the contrary, significantly increased di- and triglycerides, and decreased co-enzyme were only found in mice with HCM. Moreover, mice with DCM uniquely exhibited elevated levels of cholesterol ester. Further in-depth analysis revealed significantly altered metabolites from all the lipid classes with either similar or opposing trends in JPH2 mutant mice with HCM or DCM. Together, these studies revealed, for the first time, unique alterations in the cardiac lipid composition-including distinct increases in neutral lipids and decreases in polar membrane lipids-in mice with HCM and DCM were caused by distinct JPH2 variants. These studies may aid the development of novel biomarkers or therapeutics for these inherited disorders.

Microbial oil, alone or paired with β-glucans, can control hypercholesterolemia in a zebrafish model

Dyslipidemia is often associated with unhealthy dietary habits, and many mammalian studies have explored the mode of action of certain bioactive compounds such as β-glucans and n-3 PUFAs to understand their potential to normalize the lipid metabolism. There are only a few investigations that adopted omic approaches to unveil their combined effect on hypercholesterolemia. Zebrafish (Danio rerio) was used as a model organism to reveal the efficacy of Schizochytrium oil and β-glucans (from Euglena gracilis and Phaeodactylum tricornutum) against cholesterol-rich diet induced dyslipidemia. One of the folowing four diets was fed to a particular group of fish: a control high-cholesterol diet, a Schizochytrium oil diet or one of the two diets containing the oil and β-glucan. The plasma HDL, expression of hepatic genes linked to, among others, ferric ion binding and plasma phosphatidylcholines were higher and plasma cholesterol esters and triacylglycerols were lower in the microbial oil-fed fish compared to the fish fed high cholesterol diet. While the fish fed a mix of microbial oil and Euglena β-glucan had lower plasma triacylglycerols and expression of hepatic genes linked to PPAR signaling pathway and enriched biosynthesis of plasma unsaturated fatty acids, the fish fed microbial oil-Phaeodactylum β-glucan combination had lower abundance of triacylglycerols rich in saturated and mono-unsaturated fatty acids and cholesterol esters in the plasma.

Replacement of dietary saturated with unsaturated fatty acids is associated with beneficial effects on lipidome metabolites: a secondary analysis of a randomized trial

BACKGROUND

The effects of replacing dietary saturated fatty acids (SFAs) with monounsaturated fatty acids (MUFAs) and/or polyunsaturated fatty acids (PUFAs) on the plasma lipidome in relation to the cardiometabolic disease (CMD) risk are poorly understood.

OBJECTIVES

We aimed to assess the impact of substituting dietary SFAs with unsaturated fatty acids (UFAs) on the plasma lipidome and examine the relationship between lipid metabolites modulated by diet and CMD risk.

METHODS

Plasma fatty acid (FA) concentrations among 16 lipid classes (within-class FAs) were measured in a subgroup from the Dietary Intervention and VAScular function (DIVAS) parallel randomized controlled trial (n = 113/195), which consisted of three 16-wk diets enriched in SFAs (target SFA:MUFA:n-6PUFA ratio = 17:11:4% total energy [TE]), MUFAs (9:19:4% TE), or a MUFA/PUFA mixture (9:13:10% TE). Similar lipidomics analyses were conducted in the European investigation into Cancer and Nutrition (EPIC)-Potsdam prospective cohort study (specific case/cohorts: n = 775/1886 for type 2 diabetes [T2D], n = 551/1671 for cardiovascular disease [CVD]). Multiple linear regression and multivariable Cox models identified within-class FAs sensitive to replacement of dietary SFA with UFA in DIVAS and their association with CMD risk in EPIC-Potsdam. Elastic-net regression models identified within-class FAs associated with changes in CMD risk markers post-DIVAS interventions.

RESULTS

DIVAS high-UFA interventions reduced plasma within-class FAs associated with a higher CVD risk in EPIC-Potsdam, especially SFA-containing glycerolipids and sphingolipids (e.g., diacylglycerol (20:0) z-score = -1.08; SE = 0.17; P value < 10^-8), whereas they increased those inversely associated with CVD risk. The results on T2D were less clear. Specific sphingolipids and phospholipids were associated with changes in markers of endothelial function and ambulatory blood pressure, whereas higher low-density lipoprotein cholesterol concentrations were characterized by higher plasma glycerolipids containing lauric and stearic acids.

CONCLUSIONS

These results suggest a mediating role of plasma lipid metabolites in the association between dietary fat and CMD risk. Future research combining interventional and observational findings will further our understanding of the role of dietary fat in CMD etiology. This trial was registered in ClinicalTrials.gov as NCT01478958.

Energy metabolism disorder dictates chronic hypoxia damage in heart defect with tetralogy of fallot

Background

Tetralogy of Fallot (TOF) belongs to cyanotic heart damage, which is the most common in clinic. In the chronic myocardial hypoxia injury related to TOF, the potential molecular mechanism of cardiac energy metabolism remains unclear.

Materials and methods

In our study, microarray transcriptome analysis and metabonomics methods were used to explore the energy metabolism pathway during chronic hypoxia injury. The gene expression omnibus (GEO) dataset GSE132176 was obtained for analyzing the metabolic pathways. The clinical samples (right atrial tissues) of atrial septal defect (ASD) and TOF were analyzed by metabonomics. Next, we screened important pathways and important differential metabolites related to energy metabolism to explore the pathogenesis of TOF.

Results

Gene set enrichment analysis (GSEA) indicated that fructose 6-phosphate metabolic process, triglyceride metabolic process, and et al. were significantly enriched. Gene set variation analysis (GSVA) results showed that significant difference of ASD group and TOF group existed in terpenoid metabolic process and positive regulation of triglyceride metabolic process. Pathways with significant enrichment (impact > 0.1) in TOF were caffeine metabolism (impact = 0.69), sphingolipid metabolism (impact = 0.46), glycerophospholipid metabolism (impact = 0.26), tryptophan metabolism (impact = 0.24), galactose metabolism (impact = 0.11). Pathways with significant enrichment (impact > 0.1) in ASD are caffeine metabolism (impact = 0.69), riboflavin metabolism (impact = 0.5), alanine, aspartate and glutamate metabolism (impact = 0.35), histidine metabolism (impact = 0.34) and et al.

Conclusion

Disturbed energy metabolism occurs in patients with TOF or ASD, and further investigation was needed to further clarify mechanism.

Head-to-Head Comparison of Oxidative Stress Biomarkers for All-Cause Mortality in Hemodialysis Patients

Oxidative stress (OS) presents even in the early chronic kidney disease (CKD) stage and is exacerbated in patients with end-stage renal disease (ESRD) undergoing maintenance hemodialysis (MHD). There is still a debate over the association between oxidative stress and mortality. Our study aims to compare head-to-head the prognostic value of different oxidative markers for all-cause mortality in hemodialysis (HD) patients. We thus enrolled 347 patients on HD in this prospective study. Four OS biomarkers were measured (carbonyl proteins, myeloperoxidase (MPO), advanced oxidation protein products (AOPPs), and oxidized low-density lipoprotein (ox-LDL)). During the 60-month follow-up period, 9 patients have been lost to follow-up and 168 (48.4%) patients died. Concerning the oxidative stress (ox-stress) byproducts, carbonyl proteins were lower in survivors (105.40 ng/mL (IQR 81.30−147.85) versus 129.65 ng/mL (IQR 93.20−180.33); p < 0.001), with similar results for male patients (103.70 ng/mL (IQR 76.90−153.33) versus 134.55 ng/mL (IQR 93.95−178.68); p = 0.0014). However, there are no significant differences in MPO, AOPP, and ox-LDL between the two groups. Kaplan−Meier survival analysis indicated that patients in the higher carbonyl proteins concentration (>117.85 ng/mL group) had a significantly lower survival rate (log-rank test, p < 0.001). Univariate Cox regression analysis showed a positive correlation between carbonyl proteins and all-cause mortality in the higher and lower halves. Even after adjustment for conventional risk factors, it remained a statistically significant predictor of an increased risk of death in MHD. Univariate Cox regression analysis of MPO showed that continuous MPO and Log MPO were significantly associated with all-cause mortality, except for binary MPO (divided according to the median of MPO). Multivariate Cox analysis for MPO showed that the mortality prediction remains significant after adjusting for multiple factors. In conclusion, not all ox-stress biomarkers predict all-cause mortality in HD patients to a similar extent. In the present study, carbonyl proteins and MPO are independent predictors of all-cause mortality in HD patients, whereas AOPPs and oxLDL are clearly not associated with all-cause mortality in HD patients.

Lipidic profiles of patients starting peritoneal dialysis suggest an increased cardiovascular risk beyond classical dyslipidemia biomarkers

Patients on peritoneal dialysis (PD) have an increased risk of cardiovascular disease (CVD) and an atherogenic lipid profile generated by exposure to high glucose dialysis solutions. In the general population, the reduction of classic lipids biomarkers is associated with improved clinical outcomes; however, the same results have not been seen in PD population, a lack of data this study aims to fulfill. Single-center prospective observational study of a cohort of CKD patients who started renal replacement therapy with continuous ambulatory peritoneal dialysis. The differences in the lipid profile and analytical variables before and 6 months after the start of peritoneal dialysis were analyzed. Samples were analyzed on an Ultra-Performance Liquid Chromatography system. Thirty-nine patients were enrolled in this study. Their mean age was 57.9 ± 16.3 years. A total of 157 endogenous lipid species of 11 lipid subclasses were identified. There were significant increases in total free fatty acids (p < 0.05), diacylglycerides (p < 0.01), triacylglycerides, (p < 0.01), phosphatidylcholines (p < 0.01), phosphatidylethanolamines (p < 0.01), ceramides (p < 0.01), sphingomyelins (p < 0.01), and cholesterol esters (p < 0.01) from baseline to 6 months. However, there were no differences in the classical lipid markers, neither lysophosphatidylcholines, monoacylglycerides, and sphingosine levels. 6 months after the start of the technique, PD patients present changes in the lipidomic profile beyond the classic markers of dyslipidemia.

Tripterygium wilfordii glycosides ameliorates collagen-induced arthritis and aberrant lipid metabolism in rats

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease, and the dysregulation of lipid metabolism has been found to play an important role in the pathogenesis of RA and is related to the severity and prognosis of patients. Tripterygium wilfordii glycosides (TWG) is extracted from the roots of Tripterygium wilfordii Hook F. with anti-inflammatory and immunosuppressive effects, and numerous clinical trials have supported its efficacy in the treatment of RA. Some evidence suggested that TWG can modulate the formation of lipid mediators in various innate immune cells; however whether it can improve RA-related lipid disorders has not been systematically studied. In the study, type Ⅱ collagen-induced arthritis (CIA) model was used to investigate the efficacy of TWG in the treatment of RA and its effect on lipid metabolism. Paw volume, arthritis score, pathological changes of ankle joint, serum autoantibodies and inflammatory cytokines were detected to assess the therapeutic effect on arthritis in CIA rats. Then, shotgun lipidomics based on multi-dimensional mass spectrometry platform was performed to explore the alterations in serum lipidome caused by TWG. The study showed that TWG could effectively ameliorate arthritis in CIA rats, such as reducing paw volume and arthritis score, alleviating the pathological damages of joint, and preventing the production of anti-CII autoantibodies and IL-1β cytokine. Significant increase in ceramide and decrease in lysophosphatidylcholine were observed in CIA rats, and were highly correlated with arthritis score and IL-1β level. After TWG treatment, these lipid abnormalities can be corrected to a great extent. These data demonstrate that TWG exerts a beneficial therapeutic effect on aberrant lipid metabolism which may provide new insights for further exploring the role and mechanism of TWG in the treatment of RA.

Plasma lipid alterations in young adults with psychotic experiences: A study from the Avon Longitudinal Study of Parents and Children cohort

BACKGROUND

Psychotic experiences (PEs) are associated with an increased risk of future psychotic and non-psychotic mental disorders. The identification of biomarkers of PEs may provide insights regarding the underlying pathophysiology.

METHODS

The current study applied targeted lipidomic approaches to compare plasma lipid profiles in participants from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort who did (n = 206) or did not (n = 206) have PEs when aged approximately 24 years.

RESULTS

In total, 202 lipids including 8 lipid classes were measured by using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS). Eight lipid clusters were generated. Thirteen individual lipids were nominally significantly higher in the PEs group compared to the control group. After correction for multiple comparisons, 9 lipids comprising 3 lysophosphatidylcholines (LPCs), 2 phosphatidylcholines (PCs) and 4 triacylglycerols (TGs) remained significant. In addition, PEs cases had increased levels of TGs and LPCs with a low double bond count.

CONCLUSIONS

These findings indicate plasma lipidomic abnormalities in individuals experiencing PEs. The lipidomic profile measures could aid our understanding of the underlying pathophysiological mechanisms.

Lipidome profile predictive of disease evolution and activity in rheumatoid arthritis

Lipid mediators are crucial for the pathogenesis of rheumatoid arthritis (RA); however, global analyses have not been undertaken to systematically define the lipidome underlying the dynamics of disease evolution, activation, and resolution. Here, we performed untargeted lipidomics analysis of synovial fluid and serum from RA patients at different disease activities and clinical phases (preclinical phase to active phase to sustained remission). We found that the lipidome profile in RA joint fluid was severely perturbed and that this correlated with the extent of inflammation and severity of synovitis on ultrasonography. The serum lipidome profile of active RA, albeit less prominent than the synovial lipidome, was also distinguishable from that of RA in the sustained remission phase and from that of noninflammatory osteoarthritis. Of note, the serum lipidome profile at the preclinical phase of RA closely mimicked that of active RA. Specifically, alterations in a set of lysophosphatidylcholine, phosphatidylcholine, ether-linked phosphatidylethanolamine, and sphingomyelin subclasses correlated with RA activity, reflecting treatment responses to anti-rheumatic drugs when monitored serially. Collectively, these results suggest that analysis of lipidome profiles is useful for identifying biomarker candidates that predict the evolution of preclinical to definitive RA and could facilitate the assessment of disease activity and treatment outcomes.

Metabolomics Signatures and Subsequent Maternal Health among Mothers with a Congenital Heart Defect-Affected Pregnancy

Congenital heart defects (CHDs) are the most prevalent and serious of all birth defects in the United States. However, little is known about the impact of CHD-affected pregnancies on subsequent maternal health. Thus, there is a need to characterize the metabolic alterations associated with CHD-affected pregnancies. Fifty-six plasma samples were identified from post-partum women who participated in the National Birth Defects Prevention Study between 1997 and 2011 and had (1) unaffected control offspring (n = 18), (2) offspring with tetralogy of Fallot (ToF, n = 22), or (3) hypoplastic left heart syndrome (HLHS, n = 16) in this pilot study. Absolute concentrations of 408 metabolites using the AbsoluteIDQ^® p400 HR Kit (Biocrates) were evaluated among case and control mothers. Twenty-six samples were randomly selected from above as technical repeats. Analysis of covariance (ANCOVA) and logistic regression models were used to identify significant metabolites after controlling for the maternal age at delivery and body mass index. The receiver operating characteristic (ROC) curve and area-under-the-curve (AUC) are reported to evaluate the performance of significant metabolites. Overall, there were nine significant metabolites (p < 0.05) identified in HLHS case mothers and 30 significant metabolites in ToF case mothers. Statistically significant metabolites were further evaluated using ROC curve analyses with PC (34:1), two sphingolipids SM (31:1), SM (42:2), and PC-O (40:4) elevated in HLHS cases; while LPC (18:2), two triglycerides: TG (44:1), TG (46:2), and LPC (20:3) decreased in ToF; and cholesterol esters CE (22:6) were elevated among ToF case mothers. The metabolites identified in the study may have profound structural and functional implications involved in cellular signaling and suggest the need for postpartum dietary supplementation among women who gave birth to CHD offspring.

Analysis of Metabolic Markers in Patients with Chronic Heart Failure before and after LVAD Implantation

Chronic heart failure (HF) is a clinical syndrome characterized by functional impairments of the myocardium. Metabolic and clinical changes develop with disease progression. In an advanced state, left ventricular assist devices (LVADs) are implanted for mechanical unloading. Our study aimed to assess the effects of LVAD implantation on the metabolic phenotypes and their potential to reverse the latter in patients with advanced HF. Plasma metabolites were analyzed by LC–MS/MS in 20 patients with ischemic cardiomyopathy (ICM), 20 patients with dilative cardiomyopathy (DCM), and 20 healthy controls. Samples were collected in HF patients before, 30 days after, and >100 days after LVAD implantation. Out of 188 measured metabolites, 63 were altered in HF. Only three metabolites returned to pre-LVAD concentrations 100 days after LVAD implantation. Pre-LVAD differences between DCM and ICM were mainly observed for amino acids and biogenic amines. This study shows a reversal of metabolite abnormalities in HF as a result of LVAD implantation. The etiology of the underlying disease plays an essential role in defining which specific metabolic parameter is altered in HF and reversed by LVAD implantation. Our findings provide a detailed insight into the disease pattern of ICM and DCM and the potential for reversibility of metabolic abnormalities in HF.

Sex-Specific Relationship between the Cardiorespiratory Fitness and Plasma Metabolite Patterns in Healthy Humans-Results of the KarMeN Study

Cardiorespiratory fitness (CRF) represents a strong predictor of all-cause mortality and is strongly influenced by regular physical activity (PA). However, the biological mechanisms involved in the body's adaptation to PA remain to be fully elucidated. The aim of this study was to systematically examine the relationship between CRF and plasma metabolite patterns in 252 healthy adults from the cross-sectional Karlsruhe Metabolomics and Nutrition (KarMeN) study. CRF was determined by measuring the peak oxygen uptake during incremental exercise. Fasting plasma samples were analyzed by nuclear magnetic resonance spectroscopy and mass spectrometry coupled to one- or two-dimensional gas chromatography or liquid chromatography. Based on this multi-platform metabolomics approach, 427 plasma analytes were detected. Bi- and multivariate association analyses, adjusted for age and menopausal status, showed that CRF was linked to specific sets of metabolites primarily indicative of lipid metabolism. However, CRF-related metabolite patterns largely differed between sexes. While several phosphatidylcholines were linked to CRF in females, single lyso-phosphatidylcholines and sphingomyelins were associated with CRF in males. When controlling for further assessed clinical and phenotypical parameters, sex-specific CRF tended to be correlated with a smaller number of metabolites linked to lipid, amino acid, or xenobiotics-related metabolism. Interestingly, sex-specific CRF explanation models could be improved when including selected plasma analytes in addition to clinical and phenotypical variables. In summary, this study revealed sex-related differences in CRF-associated plasma metabolite patterns and proved known associations between CRF and risk factors for cardiometabolic diseases such as fat mass, visceral adipose tissue mass, or blood triglycerides in metabolically healthy individuals. Our findings indicate that covariates like sex and, especially, body composition have to be considered when studying blood metabolic markers related to CRF.

Cardiovascular protection effect of chlorogenic acid: focus on the molecular mechanism

Vascular endothelial cells have a variety of functions such as the control of blood coagulation, vascular permeability, and tone regulation, as well as quiesce of immune cells. Endothelial dysfunction is a cardiovascular events predictor, which is considered the initial stage in atherosclerosis development. It is characterized by alterations in endothelium functions due to imbalanced vasodilators and vasoconstrictors, procoagulant and anticoagulant mediators, as well as growth inhibitor and promotor substances. Chlorogenic acid (CGA) is the primary polyphenol in coffee and some fruits. It has many health-promoting properties, especially in the cardiovascular system. Many studies investigated the efficacy and mechanism of this compound in vascular health. CGA has several vascular benefits such as anti-atherosclerosis, anti-thrombosis, and anti-hypertensive. This review focuses on the molecular mechanism of CGA in vascular health.

Characteristic of Metabolic Status in Heart Failure and Its Impact in Outcome Perspective

Metabolic alterations have been documented in peripheral tissues in heart failure (HF). Outcomes might be improved by early identification of risk. However, the prognostic information offered is still far from enough. We hypothesized that plasma metabolic profiling potentially provides risk stratification for HF patients. Of 61 patients hospitalized due to acute decompensated HF, 31 developed HF-related events in one year after discharge (Event group), and the other 30 patients did not (Non-event group). The plasma collected during hospital admission was analyzed by an ultra-high performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOFMS)-based metabolomic approach. The orthogonal projection to latent structure discriminant analysis (OPLS-DA) reveals that the metabolomics profile is able to distinguish between events in HF. Levels of 19 metabolites including acylcarnitines, lysophospholipids, dimethylxanthine, dimethyluric acid, tryptophan, phenylacetylglutamine, and hypoxanthine are significantly different between patients with and without event (p < 0.05). Established risk prediction models of event patients by using receiver operating characteristics analysis reveal that the combination of tetradecenoylcarnitine, dimethylxanthine, phenylacetylglutamine, and hypoxanthine has better discrimination than B-type natriuretic peptide (BNP) (AUC 0.871 and 0.602, respectively). These findings suggest that metabolomics-derived metabolic profiling have the potential of identifying patients with high risk of HF-related events and provide insights related to HF outcome.

Lysophosphatidylcholines inhibit human eosinophil activation and suppress eosinophil migration in vivo

Eosinophils are important multifaceted effector cells involved in allergic inflammation. Following allergen challenge, eosinophils and other immune cells release secreted phospholipases, generating lysophosphatidylcholines (LPCs). LPCs are potent lipid mediators, and serum levels of LPCs associate with asthma severity, suggesting a regulatory activity of LPCs in asthma development. As of yet, the direct effects of LPCs on eosinophils remain unclear. In the present study, we tested the effects of the major LPC species (16:0, 18:0 and 18:1) on eosinophils isolated from healthy human donors. Addition of saturated LPCs in the presence of albumin rapidly disrupted cholesterol-rich nanodomains on eosinophil cell membranes and suppressed multiple eosinophil effector responses, such as CD11b upregulation, degranulation, chemotaxis, and downstream signaling. Furthermore, we demonstrate in a mouse model of allergic cell recruitment, that LPC treatment markedly reduces immune cell infiltration into the lungs. Our observations suggest a strong modulatory activity of LPCs in the regulation of eosinophilic inflammation in vitro and in vivo.

Metabolomic Signature of Early Vascular Aging (EVA) in Hypertension

Arterial stiffening is a hallmark of early vascular aging (EVA) syndrome and an independent predictor of cardiovascular morbidity and mortality. In this case-control study we sought to identify plasma metabolites associated with EVA syndrome in the setting of hypertension. An untargeted metabolomic approach was used to identify plasma metabolites in an age-, BMI-, and sex-matched groups of EVA (n = 79) and non-EVA (n = 73) individuals with hypertension. After raw data processing and filtration, 497 putative compounds were characterized, out of which 4 were identified as lysophosphaditylcholines (LPCs) [LPC (18:2), LPC (16:0), LPC (18:0), and LPC (18:1)]. A main finding of this study shows that identified LPCs were independently associated with EVA status. Although LPCs have been shown previously to be positively associated with inflammation and atherosclerosis, we observed that hypertensive individuals characterized by 4 down-regulated LPCs had 3.8 times higher risk of EVA compared to those with higher LPC levels (OR = 3.8, 95% CI 1.7–8.5, P < 0.001). Our results provide new insights into a metabolomic phenotype of vascular aging and warrants further investigation of negative association of LPCs with EVA status. This study suggests that LPCs are potential candidates to be considered for further evaluation and validation as predictors of EVA in patients with hypertension.

A new approach for characterization of phosphatidylcholines and lysophosphatidylcholine in human plasma

Aim: Characterization of phosphatidylcholines (PCs) and lysophosphatidylcholine in human plasma using LC-IT-MSⁿ. The characterization approach was based on trapping the eluted positive ions and applying low voltage for fragmentation to MS² and further fragmentation of the most abundant two peaks to obtain MS³. This approach allowed linking the MS³ data to MS² and precursor ion. Methodology: The fatty acid part, at sn-1 and sn-2 of the glycerol backbone, could be identified based on the favored cleavage pathway. Conclusion: The dysregulated PCs and lysophosphatidylcholines in human plasma obtained from acute coronary syndrome cases, and Type 2 diabetes patients suffering no coronary syndromes were estimated and matched versus healthy volunteers. An epoxide form of 16:0-18:2 PC was confirmed, m/z 774.6.

Lipidomic architecture shared by subclinical markers of osteoporosis and atherosclerosis: The Cardiovascular Risk in Young Finns Study

BACKGROUND

Studies have shown that osteoporosis and atherosclerosis are comorbid conditions sharing common risk factors and pathophysiological mechanisms. Understanding these is crucial in order to develop shared methods for risk stratification, prevention, diagnosis and treatment. The aim of this study was to apply a system-level bioinformatics approach to lipidome-wide data in order to pinpoint the lipidomic architecture jointly associated with surrogate markers of these complex comorbid diseases.

SUBJECTS AND METHODS

The study was based on the Cardiovascular Risk in Young Finns Study cohort from the 2007 follow-up (n = 1494, aged 30-45 years, women: 57%). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to analyse the serum lipidome, involving 437 molecular lipid species. The subclinical osteoporotic markers included indices of bone mineral density and content, measured using peripheral quantitative computer tomography from the distal and shaft sites of both the tibia and the radius. The subclinical atherosclerotic markers included carotid and bulbus intima media thickness measured with high-resolution ultrasound. Weighted co-expression network analysis was performed to identify networks of densely interconnected lipid species (i.e. lipid modules) associated with subclinical markers of both osteoporosis and atherosclerosis. The levels of lipid species (lipid profiles) of each of the lipid modules were summarized by the first principal component termed as module eigenlipid. Then, Pearson's correlation (r) was calculated between the module eigenlipids and the markers. Lipid modules that were significantly and jointly correlated with subclinical markers of both osteoporosis and atherosclerosis were considered to be related to the comorbidities. The hypothesis that the eigenlipids and profiles of the constituent lipid species in the modules have joint effects on the markers was tested with multivariate analysis of variance (MANOVA).

RESULTS

Among twelve studied molecular lipid modules, we identified one module with 105 lipid species significantly and jointly associated with both subclinical markers of both osteoporosis (r = 0.24, p-value = 2 × 10^-20) and atherosclerosis (r = 0.16, p-value = 2 × 10^-10). The majority of the lipid species in this module belonged to the glycerolipid (n = 60), glycerophospholipid (n = 13) and sphingolipid (n = 29) classes. The module was also enriched with ceramides (n = 20), confirming their significance in cardiovascular outcomes and suggesting their joint role in the comorbidities. The top three of the 37 statistically significant (adjusted p-value < 0.05) lipid species jointly associated with subclinical markers of both osteoporosis and atherosclerosis within the module were all triacylglycerols (TAGs) - TAG(18:0/18:0/18:1) with an adjusted p-value of 8.6 × 10^-8, TAG(18:0/18:1/18:1) with an adjusted p-value of 3.7 × 10^-6, and TAG(16:0/18:0/18:1) with an adjusted p-value of 8.5 × 10^-6.

CONCLUSION

This study identified a novel lipid module associated with both surrogate markers of both subclinical osteoporosis and subclinical atherosclerosis. Alterations in the metabolism of the identified lipid module and, more specifically, the TAG related molecular lipids within the module may provide potential new biomarkers for testing the comorbidities, opening avenues for the emergence of dual-purpose prevention measures.

Associations between plasma lysophospholipids concentrations, chronic kidney disease and the type of renal replacement therapy

BACKGROUND

Lysophosphatidic acid (LPA) and lysophosphatidylcholine (LPC) are bioactive lysophospholipids involved in the pathogenesis of renal diseases, especially the renal fibrosis. Plasma LPC concentrations in chronic kidney disease (CKD) patients are lower or similar to those observed in control groups, but less is known about the LPA concentrations. The main aim of the study was the analysis of associations of chronic kidney disease and renal replacement therapy with the plasma LPA concentrations. We have also analyzed the relationship between the plasma concentrations of LPA and LPC.

MATERIAL AND METHODS

Study group consisted of 110 patients with CKD in stages G3-G5 according to the KDIGO guidelines and was divided into four subgroups: treated conservatively (CT, 30 patients), on hemodialysis (HD, 30 patients), on peritoneal dialysis (PD, 30 patients) and renal transplant recipients (RT, 20 patients). In HD the blood was collected immediately before (HD D1) and after the dialysis (HD D2). In RT the blood was collected immediately before (RT D1) and 3-14 days after the transplantation (RT D2). The control group (Con) consisted of 50 healthy volunteers. Plasma concentrations of LPA and LPC were measured using enzyme-linked immunosorbent assays.

RESULTS

In CT, PD and RT D2 plasma concentrations of LPA were significantly higher, compared to Con. In HD, LPA levels did not differ compared to Con and they were significantly lower compared to PD (HD D1 and HD D2), RT D2 (HD D1 and HD D2) and CT (HD D1). However, in most of patients concentrations of LPA were within the range of reference values established in healthy volunteers. Concentrations of LPC were significantly lower in almost all patients subgroups, compared to Con, except in PD. There were no significant correlations between plasma concentrations of LPA and LPC in any of patients subgroups.

CONCLUSIONS

Presence of CKD is associated with increased plasma LPA levels and the hemodialysis therapy reduces this influence. However, only in a small percentage of patients with CKD, LPA concentrations are out of the reference range, which makes LPA not useful as a diagnostic marker for CKD. Further studies are needed to confirm and explain observed relationships.

An Updated Review of Lysophosphatidylcholine Metabolism in Human Diseases

Lysophosphatidylcholine (LPC) is increasingly recognized as a key marker/factor positively associated with cardiovascular and neurodegenerative diseases. However, findings from recent clinical lipidomic studies of LPC have been controversial. A key issue is the complexity of the enzymatic cascade involved in LPC metabolism. Here, we address the coordination of these enzymes and the derangement that may disrupt LPC homeostasis, leading to metabolic disorders. LPC is mainly derived from the turnover of phosphatidylcholine (PC) in the circulation by phospholipase A₂ (PLA₂). In the presence of Acyl-CoA, lysophosphatidylcholine acyltransferase (LPCAT) converts LPC to PC, which rapidly gets recycled by the Lands cycle. However, overexpression or enhanced activity of PLA₂ increases the LPC content in modified low-density lipoprotein (LDL) and oxidized LDL, which play significant roles in the development of atherosclerotic plaques and endothelial dysfunction. The intracellular enzyme LPCAT cannot directly remove LPC from circulation. Hydrolysis of LPC by autotaxin, an enzyme with lysophospholipase D activity, generates lysophosphatidic acid, which is highly associated with cancers. Although enzymes with lysophospholipase A₁ activity could theoretically degrade LPC into harmless metabolites, they have not been found in the circulation. In conclusion, understanding enzyme kinetics and LPC metabolism may help identify novel therapeutic targets in LPC-associated diseases.

Proton leak regulates mitochondrial reactive oxygen species generation in endothelial cell activation and inflammation - A novel concept

Mitochondria are capable of detecting cellular insults and orchestrating inflammatory responses. Mitochondrial reactive oxygen species (mtROS) are intermediates that trigger inflammatory signaling cascades in response to our newly proposed conditional damage associated molecular patterns (DAMP). We recently reported that increased proton leak regulates mtROS generation and thereby exert physiological and pathological activation of endothelial cells. Herein, we report the recent progress in determining the roles of proton leak in regulating mtROS, and highlight several important findings: 1) The majority of mtROS are generated in the complexes I and III of electron transport chain (ETC); 2) Inducible proton leak and mtROS production are mutually regulated; 3) ATP synthase-uncoupled ETC activity and mtROS regulate both physiological and pathological endothelial cell activation and inflammation initiation; 4) Mitochondrial Ca²⁺ uniporter and exchanger proteins have an impact on proton leak and mtROS generation; 5) MtROS connect signaling pathways between conditional DAMP-regulated immunometabolism and histone post-translational modifications (PTM) and gene expression. Continuous improvement of our understanding in this aspect of mitochondrial function would provide novel insights and generate novel therapeutic targets for the treatment of sterile inflammatory disorders such as metabolic diseases, cardiovascular diseases and cancers.

The CKD plasma lipidome varies with disease severity and outcome

BACKGROUND

Various alterations in lipid metabolism have been observed in patients with chronic kidney disease (CKD).

OBJECTIVES

To determine the levels of lipid species in plasma from CKD and hemodialysis (HD) patients and test their association with CKD severity and patient outcome.

METHODS

Seventy-seven patients with CKD stage 2 to HD were grouped into classes of CKD severity at baseline and followed-up for 3.5 years for the occurrence of transition to HD or death (combined outcome). Plasma levels of phosphatidylcholines (PCs), lysophosphatidylcholines (LPCs), sphingomyelins (SMs), and fatty acids were analyzed by flow-injection analysis coupled to tandem mass spectrometry or gas chromatography coupled with mass spectrometry. Kruskal Wallis rank tests and Cox regressions were used to analyze the association of lipids with CKD severity and the risk of combined outcome, respectively.

RESULTS

The plasma level of PCs, LPCs, and SMs was decreased in HD patients compared with nondialyzed CKD patients (all P < .05), whereas esterified and/or nonesterified fatty acids level did not change. Thirty-four lipids displayed significantly lower abundance in plasma of HD patients, whereas elaidic acid (C18:1ω9t) level was increased (P < .001). The total amount of LPCs and individual LPCs were associated with better outcome (P < .05). In particular, LPC 18:2 and LPC 20:3 were statistically associated with outcome in adjusted models (P < .05).

DISCUSSION

In HD patients, a reduction in plasma lipids is observed. Some of the alterations, namely reduced LPCs, were associated with the risk of adverse outcome. These changes could be related to metabolic dysfunctions.

Combined Clinical Phenotype and Lipidomic Analysis Reveals the Impact of Chronic Kidney Disease on Lipid Metabolism

Chronic kidney disease (CKD) results in significant dyslipidemia and profound changes in lipid and lipoprotein metabolism. The associated dyslipidemia, in turn, contributes to progression of CKD and its cardiovascular complications. To gain an in-depth insight into the disorders of lipid metabolism in advanced CKD, we applied UPLC-HDMS-based lipidomics to measure serum lipid metabolites in 180 patients with advanced CKD and 120 age-matched healthy controls. We found significant increases in the levels of total free fatty acids, glycerolipids, and glycerophospholipids in patients with CKD. The levels of free fatty acids, glycerolipids, and glycerophospholipids directly correlated with the level of serum triglyceride and inversely correlated with the levels of total cholesterol and eGFR. A total of 126 lipid species were identified from positive and negative ion modes. Out of 126, 113 identified lipid species were significantly altered in patients with CKD based on the adjusted FDR method. These results pointed to profound disturbance of fatty acid and triglyceride metabolisms in patients with CKD. Logistic regression analysis showed strong correlations between serum methyl hexadecanoic acid, LPC(24:1), 3-oxooctadecanoic acid, and PC(20:2/24:1) levels with eGFR and serum creatinine levels (R > 0.8758). In conclusion, application of UPLC-HDMS-based lipidomic technique revealed profound changes in lipid metabolites in patients with CKD. The observed increases in serum total fatty acids, glycerolipids, and glycerophospholipids levels directly correlated with increased serum triglyceride level and inversely correlated with the eGFR and triglyceride levels.

Plasma Lipidomics Investigation of Hemodialysis Effects by Using Liquid Chromatography-Mass Spectrometry

Chronic kidney disease (CKD) has been a global health problem that has a great possibility of being developed into uremia in the end. Hemodialysis (HD) is the most commonly used strategy for treating uremic patients; however, the patients still have a high risk of suffering various complications. It is well recognized that lipid disorder usually occurs in maintenance HD patients. To systemically study the effects of HD on lipid metabolism associated with uremia, we employed an ultraperformance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS)-based lipidomics method. A total of 87 human plasma samples from patients with prehemodialysis (pre-HD)/posthemodialysis (post-HD) treatment and the healthy controls were enrolled in the study. As compared with pre-HD patients, many plasma lipids showed significant changes (p < 0.05) in patients receiving HD therapy. Specifically, sum of free fatty acids (FFA) as well as saturated FFA and eicosanoids and sums of lyso-phosphatidylinositols and lyso-phosphatidylethanolamines, FFA 16:1/FFA 16:0, and FFA 18:1/FFA 18:0 were obviously higher in the pre-HD group than in the controls while they were significantly lower in patients after HD. These results indicated that UPLC-Q-TOF/MS-based lipidomics is a promising approach to investigate lipid alterations in relation to uremia and it is helpful to understand complex complications involved in HD patients.

The role of oxidized low-density lipoproteins in atherosclerosis: the myths and the facts

The oxidative modification hypothesis of atherosclerosis, which assigns to oxidized low-density lipoproteins (LDLs) a crucial role in atherosclerosis initiation and progression, is still debated. This review examines the role played by oxidized LDLs in atherogenesis taking into account data derived by studies based on molecular and clinical approaches. Experimental data carried out in cellular lines and animal models of atherosclerosis support the proatherogenic role of oxidized LDLs: (a) through chemotactic and proliferating actions on monocytes/macrophages, inciting their transformation into foam cells; (b) through stimulation of smooth muscle cells (SMCs) recruitment and proliferation in the tunica intima; (c) through eliciting endothelial cells, SMCs, and macrophages apoptosis with ensuing necrotic core development. Moreover, most of the experimental data on atherosclerosis-prone animals benefiting from antioxidant treatment points towards a link between oxidative stress and atherosclerosis. The evidence coming from cohort studies demonstrating an association between oxidized LDLs and cardiovascular events, notwithstanding some discrepancies, seems to point towards a role of oxidized LDLs in atherosclerotic plaque development and destabilization. Finally, the results of randomized clinical trials employing antioxidants completed up to date, despite demonstrating no benefits in healthy populations, suggest a benefit in high-risk patients. In conclusion, available data seem to validate the oxidative modification hypothesis of atherosclerosis, although additional proofs are still needed.