Integrative Analysis of the Inflammatory Bowel Disease Serum Metabolome Improves Our Understanding of Genetic Etiology and Points to Novel Putative Therapeutic Targets.

BACKGROUND & AIMS: Polygenic and environmental factors are underlying causes of inflammatory bowel disease (IBD). We hypothesized that integration of the genetic loci controlling a metabolite's abundance, with known IBD genetic susceptibility loci, may help resolve metabolic drivers of IBD. METHODS: We measured the levels of 1300 metabolites in the serum of 484 patients with ulcerative colitis (UC) and 464 patients with Crohn's disease (CD) and 365 controls. Differential metabolite abundance was determined for disease status, subtype, clinical and endoscopic disease activity, as well as IBD phenotype including disease behavior, location, and extent. To inform on the genetic basis underlying metabolic diversity, we integrated metabolite and genomic data. Genetic colocalization and Mendelian randomization analyses were performed using known IBD risk loci to explore whether any metabolite was causally associated with IBD. RESULTS: We found 173 genetically controlled metabolites (metabolite quantitative trait loci, 9 novel) within 63 non-overlapping loci (7 novel). Furthermore, several metabolites significantly associated with IBD disease status and activity as defined using clinical and endoscopic indexes. This constitutes a resource for biomarker discovery and IBD biology insights. Using this resource, we show that a novel metabolite quantitative trait locus for serum butyrate levels containing ACADS was not supported as causal for IBD; replicate the association of serum omega-6 containing lipids with the fatty acid desaturase 1/2 locus and identify these metabolites as causal for CD through Mendelian randomization; and validate a novel association of serum plasmalogen and TMEM229B, which was predicted as causal for CD. CONCLUSIONS: An exploratory analysis combining genetics and unbiased serum metabolome surveys can reveal novel biomarkers of disease activity and potential mediators of pathology in IBD.

Serum Levels of Plasmalogens and Fatty Acid Metabolites Associate with Retinal Microangiopathy in Participants from the Finnish Diabetes Prevention Study.

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes, and retinal microaneurysms (MA) are one of the first detected abnormalities associated with DR. We recently showed elevated serum triglyceride levels to be associated with the development of MA in the Finnish Diabetes Prevention Study (DPS). The purpose of this metabolomics study was to assess whether serum fatty acid (FA) composition, plasmalogens, and low-grade inflammation may enhance or decrease the risk of MA. Originally, the DPS included 522 individuals (mean 55 years old, range 40-64 years) with impaired glucose tolerance who were randomized into an intervention (n = 265) or control group (n = 257). The intervention lasted for a median of four years (active period), after which annual follow-up visits were conducted. At least five years after stopping the intervention phase of DPS, participants classified as MA negative (n = 115) or MA positive (n = 51) were included in the current study. All these participants were free of diabetes at baseline (WHO 1985) and had high-sensitive C-reactive protein (hs-CRP), serum FA composition, and selected lipid metabolites measured during the active study period. Among the markers associated with MA, the serum plasmalogen dm16:0 (p = 0.006), the saturated odd-chain FA 15.0 (pentadecanoic acid; p = 0.015), and omega-3 very long-chain FAs (p < 0.05) were associated with a decreased occurrence of MA. These associations were independent of study group and other risk factors. The association of high serum triglycerides with the MA occurrence was attenuated when these MA-associated serum lipid markers were considered. Our findings suggest that, in addition to n-3 FAs, odd-chain FA 15:0 and plasmalogen dm16:0 may contribute to a lower risk of MA in individuals with impaired glucose tolerance. These putative novel lipid biomarkers have an association with MA independently of triglyceride levels.

Shark liver oil supplementation enriches endogenous plasmalogens and reduces markers of dyslipidemia and inflammation.

Plasmalogens are membrane glycerophospholipids with diverse biological functions. Reduced plasmalogen levels have been observed in metabolic diseases; hence, increasing their levels might be beneficial in ameliorating these conditions. Shark liver oil (SLO) is a rich source of alkylglycerols that can be metabolized into plasmalogens. This study was designed to evaluate the impact of SLO supplementation on endogenous plasmalogen levels in individuals with features of metabolic disease. In this randomized, double-blind, placebo-controlled cross-over study, the participants (10 overweight or obese males) received 4-g Alkyrol® (purified SLO) or placebo (methylcellulose) per day for 3 weeks followed by a 3-week washout phase and were then crossed over to 3 weeks of the alternate placebo/Alkyrol® treatment. SLO supplementation led to significant changes in plasma and circulatory white blood cell lipidomes, notably increased levels of plasmalogens and other ether lipids. In addition, SLO supplementation significantly decreased the plasma levels of total free cholesterol, triglycerides, and C-reactive protein. These findings suggest that SLO supplementation can enrich plasma and cellular plasmalogens and this enrichment may provide protection against obesity-related dyslipidemia and inflammation.

Maternal lipidomic signatures in relation to spontaneous preterm birth and large-for-gestational age neonates.

Lipidome-wide metabolites may be useful biomarkers of pregnancy outcomes. We sought to characterize maternal lipidomic signatures associated with preterm birth and neonatal anthropometric parameters. Plasma samples were collected 24-28 weeks gestation, and lipidomic profiling was quantified using high-performance liquid chromatography tandem mass spectrometry. Lipid metabolites were analyzed individually and as whole lipid classes and subgroups based on degree of hydrocarbon chain saturation. Associations were estimated using linear and logistic regression. After false discovery adjustment (q < 0.15), four plasmenyl-phosphatidylethanolamines and three free fatty acids associated with increased risk for spontaneous preterm birth. Five phosphatidylinositols, two phosphatidylglycerols, and one phosphatidic acid were associated with large for gestational age neonates. The saturated plasmenyl-phosphatidylethanolamines held the association with increased risk for spontaneous preterm birth. Both the mono- and poly-unsaturated free fatty acids held the association for increased risk for spontaneous preterm birth. Mono- and poly-unsaturated phosphatidylinositols were associated with large for gestational age neonates. Whole lipid classes (plasmenyl-phophatidylcholines and plasmenyl-phosphatidylethanolamines) were associated with increased risk for large for gestational age at delivery. This study provides evidence that finer omics-scale analysis of the maternal lipidome may be more informative biomarkers of pregnancy outcomes compared to whole class level lipid analysis.

Metabolomic basis for response to high dose vitamin D in critical illness.

BACKGROUND & AIMS: It is unclear if intervention can mitigate the dramatic alterations of metabolic homeostasis present in critical illness. Our objective was to determine the associations between increased 25-hydroxyvitamin D levels following high dose vitamin D3 and more favorable metabolomic profiles in critical illness. METHODS: We performed a post-hoc metabolomics study of the VITdAL-ICU randomized double-blind, placebo-controlled trial. Trial patients from Medical and Surgical Intensive Care Units at a tertiary university hospital with 25-hydroxyvitamin D level ≤20 ng/mL received either high dose oral vitamin D3 (540,000 IU) or placebo. We performed an analysis of 578 metabolites from 1215 plasma samples from 428 subjects at randomization (day 0), day 3 and 7. Using mixed-effects modeling, we studied changes in metabolite profiles in subjects receiving intervention or placebo relative to absolute increases in 25-hydroxyvitamin D levels from day 0 to day 3. RESULTS: 55.2% of subjects randomized to high dose vitamin D3 demonstrated an absolute increase in 25-hydroxyvitamin D ≥ 15 ng/ml from day 0 to day 3. With an absolute increase in 25-hydroxyvitamin D ≥ 15 ng/ml, multiple members of the sphingomyelin, plasmalogen, lysoplasmalogen and lysophospholipid metabolite classes had significantly positive Bonferroni corrected associations over time. Further, multiple representatives of the acylcarnitine and phosphatidylethanolamine metabolite classes had significantly negative Bonferroni corrected associations over time with an absolute increase in 25-hydroxyvitamin D ≥ 15 ng/ml. Changes in these highlighted metabolite classes were associated with decreased 28-day mortality. CONCLUSIONS: Increases in 25-hydroxyvitamin D following vitamin D3 intervention are associated with favorable changes in metabolites involved in endothelial protection, enhanced innate immunity and improved mitochondrial function.

Circulating ethanolamine plasmalogen indices in Alzheimer's disease: Relation to diagnosis, cognition, and CSF tau.

INTRODUCTION: Altered lipid metabolism is implicated in Alzheimer's disease (AD), but the mechanisms remain obscure. Aging-related declines in circulating plasmalogens containing omega-3 fatty acids may increase AD risk by reducing plasmalogen availability. METHODS: We measured four ethanolamine plasmalogens (PlsEtns) and four closely related phosphatidylethanolamines (PtdEtns) from the Alzheimer's Disease Neuroimaging Initiative (ADNI; n = 1547 serum) and University of Pennsylvania (UPenn; n = 112 plasma) cohorts, and derived indices reflecting PlsEtn and PtdEtn metabolism: PL-PX (PlsEtns), PL/PE (PlsEtn/PtdEtn ratios), and PBV (plasmalogen biosynthesis value; a composite index). We tested associations with baseline diagnosis, cognition, and cerebrospinal fluid (CSF) AD biomarkers. RESULTS: Results revealed statistically significant negative relationships in ADNI between AD versus CN with PL-PX (P = 0.007) and PBV (P = 0.005), late mild cognitive impairment (LMCI) versus cognitively normal (CN) with PL-PX (P = 2.89 × 10-5 ) and PBV (P = 1.99 × 10-4 ), and AD versus LMCI with PL/PE (P = 1.85 × 10-4 ). In the UPenn cohort, AD versus CN diagnosis associated negatively with PL/PE (P = 0.0191) and PBV (P = 0.0296). In ADNI, cognition was negatively associated with plasmalogen indices, including Alzheimer's Disease Assessment Scale 13-item cognitive subscale (ADAS-Cog13; PL-PX: P = 3.24 × 10-6 ; PBV: P = 6.92 × 10-5 ) and Mini-Mental State Examination (MMSE; PL-PX: P = 1.28 × 10-9 ; PBV: P = 6.50 × 10-9 ). In the UPenn cohort, there was a trend toward a similar relationship of MMSE with PL/PE (P = 0.0949). In ADNI, CSF total-tau was negatively associated with PL-PX (P = 5.55 × 10-6 ) and PBV (P = 7.77 × 10-6 ). Additionally, CSF t-tau/Aß1-42 ratio was negatively associated with these same indices (PL-PX, P = 2.73 × 10-6 ; PBV, P = 4.39 × 10-6 ). In the UPenn cohort, PL/PE was negatively associated with CSF total-tau (P = 0.031) and t-tau/Aß1-42 (P = 0.021). CSF Aß1-42 was not significantly associated with any of these indices in either cohort. DISCUSSION: These data extend previous studies by showing an association of decreased plasmalogen indices with AD, mild cognitive impairment (MCI), cognition, and CSF tau. Future studies are needed to better define mechanistic relationships, and to test the effects of interventions designed to replete serum plasmalogens.

A conjunctive lipidomic approach reveals plasma ethanolamine plasmalogens and fatty acids as early diagnostic biomarkers for colorectal cancer patients.

Background: Colorectal cancer (CRC) represents a third leading cause of cancer-related death worldwide. The reliable diagnostic biomarkers for detecting CRC at early stage is critical for decreasing the mortality.Method: A conjunctive lipidomic approach was employed to investigate the differences in plasma lipid profiles of CRC patients (n = 101) and healthy volunteers (n = 52). Based on UHPLC-Q-TOF MS and UHPLC-QQQ MS platforms, a total of 236 lipids were structurally detected. Multivariate data analysis was conducted for biomarkers discovery.Results: A total of 11 lipid species, including 1 Glycerophosphoethanolamine (PE), 3 ethanolamine plasmalogens (PlsEtn), 1 plasmanyl glycerophosphatidylethanolamine (PE-O), 3 fatty acids (FFA), 1 Fatty acid ester of hydroxyl fatty acid (FAHFA) and 2 Diacylglycerophosphates (PA) were identified to distinguish the CRC patients at early stage from healthy controls. In addition, these potential lipid biomarkers achieved an estimated AUC=0.981 in a validation set for univariate ROC analysis.Conclusion: By combining Q-TOF MS and QQQ MS analysis, the 11 lipids exhibited good performance in differentiating early-stage CRC and healthy control. This study also demonstrated that lipidomics is a powerful tool in discovering new potential biomarkers for cancer diagnosis.

Tumor Resection Induces Alterations on Serum Phospholipidome of Liver Cancer Patients.

Hepatocellular carcinoma and cholangiocarcinoma are the most common primary malignant liver tumors. Since the liver plays a key role in lipid metabolism, the study of serum phospholipid (PL) profiles may provide a better understanding of alterations in hepatic lipid metabolism. In this study, we used a high-resolution HILIC-LC-MS lipidomic approach to establish the serum phospholipidome profile of patients with liver cancer before (T0) and after tumor resection (T1) and a control group (CT) of healthy individuals. After the analysis of PL profiles, we observed that the phospholipidome of patients with liver cancer was significantly modified after the tumor resection procedure. We observed an upregulation of some phosphatidylcholine (PtdCho) species, namely, PtdCho(36:6), PtdCho(42:6), PtdCho(38:5), PtdCho(36:5), PtdCho(38:6) and choline plasmalogens (PlsCho), and/or 1-O-alkyl-2-acyl-glycerophosphocholine (PakCho) in patients with liver cancer at T0 compared to the CT group, and a downregulation after tumor resection (T1) when compared to T0. These results show that LC-MS can detect different serum PL profiles in patients with liver cancer, before and after tumor resection, by defining a specific PL fingerprint that was used to determine the effect of tumor and tumor resection on lipid metabolism.

Role of lipids in pathophysiology, diagnosis and therapy of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is an aggressive and widespread cancer. Patients with liver cirrhosis of different aetiologies are at a risk to develop HCC. It is important to know that in approximately 20% of cases primary liver tumors arise in a non-cirrhotic liver. Lipid metabolism is variable in patients with chronic liver diseases, and lipid metabolites involved therein do play a role in the development of HCC. Of note, lipid composition of carcinogenic tissues differs from non-affected liver tissues. High cholesterol and low ceramide levels in the tumors protect the cells from oxidative stress and apoptosis, and do also promote cell proliferation. So far, detailed characterization of the mechanisms by which lipids enable the development of HCC has received little attention. Evaluation of the complex roles of lipids in HCC is needed to better understand the pathophysiology of HCC, the later being of paramount importance for the development of urgently needed therapeutic interventions. Disturbed hepatic lipid homeostasis has systemic consequences and lipid species may emerge as promising biomarkers for early diagnosis of HCC. The challenge is to distinguish lipids specifically related to HCC from changes simply related to the underlying liver disease. This review article discusses aberrant lipid metabolism in patients with HCC.

Plasma lipid profile associates with the improvement of psychological well-being in individuals with perceived stress symptoms.

Psychological stress is a suggested risk factor of metabolic disorders, but molecular mediators are not well understood. We investigated the association between the metabolic profiles of fasting plasma and the improvement of psychological well-being using non-targeted liquid chromatography-mass spectrometry (LC-MS) platform. The metabolic profiles of volunteers participating in the face-to-face intervention group (n = 60) in a randomised lifestyle intervention were compared to ones of controls (n = 64) between baseline and 36-week follow-up. Despite modest differences in metabolic profile between groups, we found associations between phosphatidylcholines (PCs) and several parameters indicating stress, adiposity, relaxation, and recovery. The relief of heart-rate-variability-based stress had positive, while improved indices of recovery and relaxation in the intervention group had an inverse association with the reduction of e.g. lysophosphatidylcholines (LPC). Interleukin-1 receptor antagonist and adiposity correlated positively with the suppressed PCs and negatively with the elevated plasmalogens PC(P-18:0/22:6) and PC(P-18:0/20:4). Also, we found changes in an unknown class of lipids over time regardless of the intervention groups, which also correlated with physiological and psychological markers of stress. The associations between lipid changes with some markers of psychological wellbeing and body composition may suggest the involvement of these lipids in the shared mechanisms between psychological and metabolic health.

Therapeutic Efficacy of Plasmalogens for Alzheimer's Disease, Mild Cognitive Impairment, and Parkinson's Disease in Conjunction with a New Hypothesis for the Etiology of Alzheimer's Disease.

It has been reported in recent years that blood levels of plasmalogens (Pls) are decreased in various diseases. None of those reports, however, conducted any clinical trials to examine the effect of Pls on those diseases. This article describes our recent report on a therapeutic efficacy of orally administered Pls in mild cognitive impairment (MCI), mild to severe Alzheimer's disease (AD), and Parkinson's disease (PD). A 24-week, multicenter, randomized, double-blind, placebo-controlled trial was performed in patients with MCI (n = 178) and mild AD (n = 98). The study design for moderate AD (n = 57) and severe AD (n = 18) was 12-week open-labeled, and the design for patients with PD (n = 10) was 24-week open-labeled. They showed a significant improvement in cognitive function and other clinical symptoms with elevation of the blood Pls levels. No adverse events were reported. The baseline levels of plasma ethanolamine plasmalogen and erythrocyte ethanolamine plasmalogen in MCI, AD, and PD were significantly lower than those of normal aged. The degree of reduction in the blood Pls levels was in the order of MCI â‰º mild AD ≺ moderate AD ≺ severe AD ≺ PD. The findings suggest that the blood levels of Pls may be a beneficial biomarker for assessing AD severity. Based on these results, we have proposed a new hypothesis for the etiology of AD and other neuropsychiatric disorders.

Altered ethanolamine plasmalogen and phosphatidylethanolamine levels in blood plasma of patients with bipolar disorder.

AIM: Ethanolamine-containing phospholipids are synthesized in endoplasmic reticulum (ER) and mitochondria. ER stress and mitochondrial dysfunction have been implicated in bipolar disorder (BP). In this study, we aimed to examine the relationship of ethanolamine plasmalogen (PLE) and phosphatidylethanolamine (PTE) levels in blood plasma with BP. METHODS: Plasma PLE and PTE levels were compared between 34 patients with BP (DSM-IV) and 38 healthy control participants matched for age, sex, and ethnicity (Japanese). Furthermore, the relationships of plasma PLE and PTE levels with clinical variables were explored. RESULTS: Plasma PLE levels were significantly lower in patients with BP than in healthy controls (P = 0.0033). In subgroup analyses, plasma PLE levels were significantly lower in patients with BP type I (BP I) than in healthy controls (P = 0.0047); furthermore, plasma PTE levels were significantly lower in patients with BP I than in controls (P = 0.016) and patients with BP type II (BP II) (P = 0.010). Receiver-operating characteristic curve analysis revealed that the discriminatory power of plasma PTE levels for distinguishing between BP I and II was fair (area under the curve = 0.78; P = 0.0095). There were no significant correlations of plasma PLE or PTE levels with depression or manic symptoms in patients. CONCLUSIONS: Plasma PLE and PTE levels were associated with BP I, but not with BP II. Moreover, plasma PTE levels differed between patients with BP I and II. Our findings highlight the importance of ethanolamine phospholipids in the pathophysiology of BP, especially BP I.

Neuroprotection and immunomodulation in the gut of parkinsonian mice with a plasmalogen precursor.

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. It is typically associated with motor symptoms originating from the degeneration of nigrostriatal dopamine (DA) neurons. Early stages of PD have been associated with an alteration in DA production in intestinal DAergic neurons along with inflammation. Interestingly, decreased serum concentrations of ethanolamine plasmalogens (PlsEtn) have been reported in PD patients. Ethanolamine plasmalogens play a role in vesicular fusion and release during neurotransmission, and store neuroprotective polyunsaturated fatty acids, such as docosahexaenoic acid (DHA) and are strong anti-oxidants, highlighting areas of potential therapeutic interest. Docosahexaenoic acid is known to play important roles in both the central nervous and peripheral systems, in addition to acting as a precursor of several molecules that regulate the resolution of inflammation. The present study investigated the neuroprotective and anti-inflammatory properties of the DHA-containing PlsEtn precursor, PPI-1011, in the intestine of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice. Treatment with PPI-1011 prevented the MPTP-induced decrease in PlsEtn levels. In addition it prevented the loss of tyrosine hydroxylase (TH) expression and reduced the infiltration of macrophages in the myenteric plexus of MPTP-treated mice. The protective effects of PPI-1011 were observed regardless of whether it was administered pre- or post- MPTP treatment. These results suggest that PPI-1011 has neuroprotective and anti-inflammatory properties in the gut and indicate its potential utility as a treatment for both early and more advanced stages of PD.

Lipidomics unveils lipid dyshomeostasis and low circulating plasmalogens as biomarkers in a monogenic mitochondrial disorder.

Mitochondrial dysfunction characterizes many rare and common age-associated diseases. The biochemical consequences, underlying clinical manifestations, and potential therapeutic targets, remain to be better understood. We tested the hypothesis that lipid dyshomeostasis in mitochondrial disorders goes beyond mitochondrial fatty acid ß-oxidation, particularly in liver. This was achieved using comprehensive untargeted and targeted lipidomics in a case-control cohort of patients with Leigh syndrome French-Canadian variant (LSFC), a mitochondrial disease caused by mutations in LRPPRC, and in mice harboring liver-specific inactivation of Lrpprc (H-Lrpprc-/-). We discovered a plasma lipid signature discriminating LSFC patients from controls encompassing lower levels of plasmalogens and conjugated bile acids, which suggest perturbations in peroxisomal lipid metabolism. This premise was reinforced in H-Lrpprc-/- mice, which compared with littermates recapitulated a similar, albeit stronger peroxisomal metabolic signature in plasma and liver including elevated levels of very-long-chain acylcarnitines. These mice also presented higher transcript levels for hepatic markers of peroxisome proliferation in addition to lipid remodeling reminiscent of nonalcoholic fatty liver diseases. Our study underscores the value of lipidomics to unveil unexpected mechanisms underlying lipid dyshomeostasis ensuing from mitochondrial dysfunction herein implying peroxisomes and liver, which likely contribute to the pathophysiology of LSFC, but also other rare and common mitochondrial diseases.

Composition of plasmalogens in serum lipoproteins from patients with non-alcoholic steatohepatitis and their susceptibility to oxidation.

BACKGROUND: Plasmalogens are ether phospholipids (PL) with an alkenyl group including vinyl ether bound at the sn-1 position and a polyunsaturated fatty acid bound at the sn-2 position, and are susceptible to oxidation. To date, there are no reports on the relationship between plasmalogen in serum lipoproteins and non-alcoholic steatohepatitis (NASH), caused by multiple factors including oxidative stress. Here, we have investigated the distribution of plasmalogens in serum lipoproteins isolated from NASH patients and healthy volunteers. METHODS: Serum lipoproteins were separated by gel-filtration chromatography, and analyzed for ethanolamine and choline plasmalogens using liquid chromatography-mass spectrometry. RESULTS: Both plasmalogen levels were higher in HDL than in VLDL or LDL. The plasmalogens/PL ratio was significantly lower in NASH than controls, for all lipoprotein fractions. Ethanolamine plasmalogens containing 20:4 and 22:6 at the sn-2 position and choline plasmalogens containing 16:0 at the sn-1 position were predominant in each group. In oxidation test using LDL from healthy serum, both types of plasmalogens were decreased during the early stages of oxidation. CONCLUSION: Plasmalogens could be a potential biomarker for evaluating the early stages of oxidation in NASH.

Supplemental feeding of phospholipid-enriched alkyl phospholipid from krill relieves spontaneous atopic dermatitis and strengthens skin intercellular lipid barriers in NC/Nga mice.

Plasmalogen (Pls) is a glycerophospholipid derived from alkyl phospholipid (Alk) with antioxidant functions in vivo. The present study investigated the effects of ether phospholipids, such as Pls and Alk, on intercellular lipid barriers in the skin of NC/Nga mice, a model of atopic dermatitis (AD). NC/Nga mice fed Alk showed increased plasma levels of Alk and Pls. The AD-related changes in ceramide composition in the skin were abrogated by oral administration of Alk. Moreover, Alk suppressed skin inflammation in AD mice. These results indicate that Alk partially fortifies the stratum corneum lipid barrier and may be an effective treatment for AD. Abbreviations: Pls: plasmalogen; PlsCho: choline plasmalogen; PlsEtn: ethanolamine plasmalogen; Alk: alkyl phospholipid; TJ: tight junction; FA: fatty acid; AD: atopic dermatitis; SO: soybean oil; FO: fish oil; DHA: docosahexaenoic acid; EPA: eicosapentaenoic acid; TG: triglyceride; PL: phospholipid; RF: retention factor; AlkCho: choline-type alkyl phospholipid; AlkEtn: ethanolamine-type alkyl phospholipid; LC-MS/MS: liquid chromatography-tandem mass spectrometry; FAR1: fatty acyl-coenzyme (Co)A reductase 1.

Serum Ethanolamine Plasmalogen and Urine Myo-Inositol as Cognitive Decline Markers.

Recent studies have suggested that metabolic disorders, particularly type 2 diabetes mellitus (T2DM), and dementia, including Alzheimer's disease (AD), were linked at the clinical and molecular levels. Brain insulin deficiency and resistance may be key events in AD pathology mechanistically linking AD to T2DM. Ethanolamine plasmalogens (PlsEtns) are abundant in the brain and play essential roles in neuronal function and myelin formation. As such, PlsEtn deficiency may be pathologically relevant in some neurodegenerative disorders such as AD. Decreased brain PlsEtn associated with dementia may reflect serum PlsEtn deficiency. We hypothesized that myo-inositol plays a role in myelin formation through its facilitation of PlsEtn biosynthesis. Excessive urinary myo-inositol (UMI) loss would likely result in PlsEtn deficiency potentially leading to demyelinating diseases such as dementia. Accordingly, measurement of both serum PlsEtn and baseline UMI excretion could improve the detection of cognitive impairment (CI) in a more specific and reliable manner. To verify our hypothesis, we conducted a clinical observational study of memory clinic outpatients (MCO) and cognitively normal elderly (NE) for nearly 4.5years. We demonstrated that serum PlsEtn concentration associated with UMI excretion was useful for predicting advancing dementia in patients with mild CI. Because hyperglycemia and associated insulin resistance might be a leading cause of increased baseline UMI excretion, serum PlsEtn quantitation would be useful in detecting CI among the elderly with hyperglycemia. Our findings suggest that myo-inositol is a novel candidate molecule linking T2DM to AD.

Alterations in the Plasma Levels of Specific Choline Phospholipids in Alzheimer's Disease Mimic Accelerated Aging.

Alzheimer's disease (AD) is the most common neurodegenerative disease and of continuously rising prevalence. The identification of easy-to-measure biomarkers capable to assist in the prediction and early diagnosis of AD is currently a main research goal. Lipid metabolites in peripheral blood of human patients have recently gained major attention in this respect. Here, we analyzed plasma of 174 participants (not demented at baseline; mean age: 75.70±0.44 years) of the Vienna Transdanube Aging (VITA) study, a longitudinal, population-based birth cohort study, at baseline and after 90 months or at diagnosis of probable AD. We determined the levels of specific choline phospholipids, some of which have been suggested as potential biomarkers for the prediction of AD. Our results show that during normal aging the levels of lysophosphatidylcholine, choline plasmalogen, and lyso-platelet activating factor increase significantly. Notably, we observed similar but more pronounced changes in the group that developed probable AD. Thus, our results imply that, in terms of choline-containing plasma phospholipids, the conversion to AD mimics an accelerated aging process. We conclude that age, even in the comparatively short time frame between 75 and 82.5 years, is a crucial factor in the quest for plasma lipid biomarkers for AD that must be carefully considered in future studies and trials.

Association of cholesterol efflux capacity with plasmalogen levels of high-density lipoprotein: A cross-sectional study in chronic kidney disease patients.

BACKGROUND AND AIM: Current research suggests that dysfunctional high-density lipoprotein (HDL) with low cholesterol efflux capacity may accelerate atherosclerosis, particularly in chronic kidney disease (CKD). We previously reported that serum levels of plasmalogens closely correlated with HDL concentration, and could serve as a novel biomarker for atherosclerosis. In the present study, we analyzed the association of cholesterol efflux capacity of HDL with clinical and biochemical parameters, including plasmalogens, in CKD patients. METHODS: We enrolled 24 mild-to-moderate CKD patients (CKD-3-4) and 33 end-stage renal disease (ESRD) patients nearing hemodialysis (CKD-5), and assessed physiological atherosclerotic scores, cholesterol efflux capacity, and plasmalogens levels in HDL. Furthermore, the effect of plasmalogen on cholesterol efflux capacity of HDL was examined by in vitro studies with re-constituted HDL (rHDL) and HDL prepared from CKD-5 patient (ESRD-HDL) with additional phospholipids. RESULTS: There were significant differences in many parameters between the two groups. In particular, plasmalogens levels and cholesterol efflux capacity of HDL were significantly reduced in the CKD-5 group compared to those in the CKD-3-4 group (-35.1%, p < 0.001, -36.8%, p < 0.001, respectively). Multivariate linear regression analyses revealed that ethanolamine plasmalogen levels of HDL were independently associated with cholesterol efflux capacity (p = 0.045) and plaque scores (p = 0.035). In vitro studies also indicated that additional plasmalogens augmented cholesterol efflux ability of HDL. CONCLUSIONS: High plasmalogens concentrations in HDL may correlate with acceleration of cholesterol efflux and their decreased levels may promote atherosclerosis in advanced CKD patients.

Myoglobinemia markers with potential applications in forensic sample analysis: lipid markers in myoglobinemia for postmortem blood.

The crush syndrome, in which rhabdomyolysis and trauma occur as a result of heat stroke and drug intoxication, can lead to myoglobinemia. This condition can be diagnosed by measuring myoglobin (Mb) levels in blood and urine. However, postmortem Mb levels are unreliable indicators, since blood Mb concentration drastically increases within a very short time after death and urine cannot always be obtained at dissection; this makes it difficult to diagnose myoglobinemia in a corpse. To address this issue, in this study, we used a lipidomics approach to identify markers that can be used to detect myoglobinemia in postmortem blood samples. We found that increases in levels of fatty acid oxides such as stearic, oleic, linoleic, and arachidonic acid and decreases in levels of plasmalogens and phosphatidylethanolamine in the blood were associated with high Mb level. These results demonstrate that postmortem samples are amenable to lipidomics analysis and provide a set of markers other than Mb that can be used for postmortem diagnosis of myoglobinemia.