Differences in levels of phosphatidylinositols in healthy and stable Coronary Artery Disease subjects revealed by HILIC-MRM method with SERRF normalization.

Quantification of endogenous biomarkers in clinical studies requires careful evaluation of a number of assay performance parameters. Comparisons of absolute values from several clinical studies can enable retrospective analyses further elucidating the biology of a given biomarker across various study populations. We characterized the performance of a highly multiplex bioanalytical method for quantification of phosphatidylinositols (PI). Hydrophilic interaction chromatography (HILIC) and multiple reaction monitoring (MRM) were employed for targeted multiplex quantification. Odd-chain PI species that are not normally present in human plasma were utilized as surrogate analytes (SA) to assess various assay performance parameters and establish a definitive dynamic linear range for PI lipids. To correct for batch effects, Systematic Error Removal using Random Forest (SERRF) normalization algorithm was employed and used to bridge raw values between two clinical studies, enabling quantitative comparison of their absolute values. A high throughput method was developed, qualified, transferred to an automation platform and applied to sample testing in two clinical trials in healthy volunteers (NCT03001297) and stable Coronary Artery Disease (CAD, NCT03351738) subjects. The method demonstrated acceptable precision and accuracy (±30%) over linear range of 1-1000 nM for SA and 8-fold dilutional linearity for endogenous PI. We determined that mean-adjusted average QC performed best for normalization using SERRF. The comparison of two studies revealed that healthy subject levels of PI are consistently higher across PI species compared to CAD subjects identifying a potential lipid biomarker to be explored in future studies.

A Novel Relative High-Density Lipoprotein Index to Predict the Structural Changes in High-Density Lipoprotein and Its Ability to Inhibit Endothelial-Mesenchymal Transition.

Therapeutic elevation of high-density lipoprotein (HDL) is thought to minimize atherogenesis in subjects with dyslipidemia. However, this is not the case in clinical practice. The function of HDL is not determined by its concentration in the plasma but by its specific structural components. We previously identified an index for the prediction of HDL functionality, relative HDL (rHDL) index, and preliminarily explored that dysfunctional HDL (rHDL index value > 2) failed to rescue the damage to endothelial progenitor cells (EPCs). To confirm the effectiveness of the rHDL index for predicting HDL functions, here we evaluated the effects of HDL from patients with different rHDL index values on the endothelial-mesenchymal transition (EndoMT) of EPCs. We also analyzed the lipid species in HDL with different rHDL index values and investigated the structural differences that affect HDL functions. The results indicate that HDL from healthy adults and subjects with an rHDL index value < 2 protected transforming growth factor (TGF)-ß1-stimulated EndoMT by modulating Smad2/3 and Snail activation. HDL from subjects with an rHDL index value > 2 failed to restore the functionality of TGF-ß1-treated EPCs. Lipidomic analysis demonstrated that HDL with different rHDL index values may differ in the composition of triglycerides, phosphatidylcholine, and phosphatidylinositol. In conclusion, we confirmed the applicability of the rHDL index value to predict HDL function and found structural differences that may affect the function of HDL, which warrants further in-depth studies.

Identifying the Lipidomic Effects of a Rare Loss-of-Function Deletion in ANGPTL3.

BACKGROUND: The identification and understanding of therapeutic targets for atherosclerotic cardiovascular disease is of fundamental importance given its global health and economic burden. Inhibition of ANGPTL3 (angiopoietin-like 3) has demonstrated a cardioprotective effect, showing promise for atherosclerotic cardiovascular disease treatment, and is currently the focus of ongoing clinical trials. Here, we assessed the genetic basis of variation in ANGPTL3 levels in the San Antonio Family Heart Study. METHODS: We assayed ANGPTL3 protein levels in ≈1000 Mexican Americans from extended pedigrees. By drawing upon existing plasma lipidome profiles and genomic data we conducted analyses to understand the genetic basis to variation in ANGPTL3 protein levels, and accordingly the correlation with the plasma lipidome. RESULTS: In a variance components framework, we identified that variation in ANGPTL3 was significantly heritable (h2=0.33, P=1.31×10-16). To explore the genetic basis of this heritability, we conducted a genome-wide linkage scan and identified significant linkage (logarithm of odds =6.18) to a locus on chromosome 1 at 90 centimorgans, corresponding to the ANGPTL3 gene location. In the genomes of 23 individuals from a single pedigree, we identified a loss-of-function variant, rs398122988 (N121Kfs*2), in ANGPTL3, that was significantly associated with lower ANGPTL3 levels (ß=-1.69 SD units, P=3.367×10-13), and accounted for the linkage signal at this locus. Given the known role of ANGPTL3 as an inhibitor of endothelial and lipoprotein lipase, we explored the association of ANGPTL3 protein levels and rs398122988 with the plasma lipidome and related phenotypes, identifying novel associations with phosphatidylinositols. CONCLUSIONS: Variation in ANGPTL3 protein levels is heritable and under significant genetic control. Both ANGPTL3 levels and loss-of-function variants in ANGPTL3 have significant associations with the plasma lipidome. These findings further our understanding of ANGPTL3 as a therapeutic target for atherosclerotic cardiovascular disease.

Expression of PRIP, a phosphatidylinositol 4,5-bisphosphate binding protein, attenuates PI3K/AKT signaling and suppresses tumor growth in a xenograft mouse model.

Cancer is characterized by uncontrolled proliferation resulting from aberrant cell cycle progression. The activation of phosphatidylinositol 3-kinase (PI3K)/AKT signaling, a regulatory pathway for the cell cycle, stabilizes cyclin D1 in the G1 phase by inhibiting the activity of glycogen synthase kinase 3ß (GSK3ß) via phosphorylation. We previously reported that phospholipase C-related catalytically inactive protein (PRIP), a phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] binding protein, regulates PI3K/AKT signaling by competitively inhibiting substrate recognition by PI3K. Therefore, in this study, we investigated whether PRIP is involved in cell cycle progression. PRIP silencing in MCF-7 cells, a human breast cancer cell line, demonstrated PI(3,4,5)P3 signals accumulated at the cell periphery compared to that of the control. This suggests that PRIP reduction enhances PI(3,4,5)P3-mediated signaling. Consistently, PRIP silencing in MCF-7 cells exhibited increased phosphorylation of AKT and GSK3ß which resulted in cyclin D1 accumulation. In contrast, the exogenous expression of PRIP in MCF-7 cells evidenced stronger downregulation of AKT and GSK3ß phosphorylation, reduced accumulation of cyclin D1, and diminished cell proliferation in comparison to control cells. Flow cytometry analysis indicated that MCF-7 cells stably expressing PRIP attenuate cell cycle progression. Importantly, tumor growth of MCF-7 cells stably expressing PRIP was considerably prevented in an in vivo xenograft mouse model. In conclusion, PRIP expression downregulates PI3K/AKT/GSK3ß-mediated cell cycle progression and suppresses tumor growth. Therefore, we propose that PRIP is a new therapeutic target for anticancer therapy.

Altered Expression Profile of Phosphatidylinositols in Erythrocytes of Alzheimer's Disease and Amnestic Mild Cognitive Impairment Patients.

BACKGROUND: Studies have demonstrated that the levels of phospholipids, including phosphatidylinositols (PIs), were decreased in Alzheimer's disease (AD) brain, presenting as a potential biomarker for AD. The plasma phospholipids levels have also been discovered to predict the conversion of cognitively normal elderly adults to amnestic mild cognitive impairment (aMCI) or demented patients. OBJECTIVE: To investigate the expression profile of PIs in erythrocytes of AD and aMCI patients, which would serve as a blood-based method to distinguish AD and aMCI patients from normal controls (NC). METHODS: In this study, we used anion-exchange high-performance liquid chromatography to analyze PIs alterations in erythrocytes from a total of 86 prospectively recruited subjects (including 24 NC, 21 aMCI patients, and 41 AD patients). RESULTS: We found that the levels of PI40 : 4, PI3/5P, and PI(3,4)P2 in aMCI patients, and the levels of PI4P, PI(3,4)P2, and PI3/5P in AD patients were significantly decreased compared to NC. The changed expression profile of PIs could effectively discriminate AD and aMCI patients from NC (AUC = 0.964, 0.938, respectively). CONCLUSION: The altered expression profile of erythrocytes PIs might be a potential blood-based biomarker for AD and aMCI. This alteration of PIs probably reflected the impaired deformability and oxygen-carrying capacity of erythrocytes in AD and aMCI patients.

Plasma lipidomic signatures of spontaneous obese rhesus monkeys.

BACKGROUND: Obesity plays crucial roles in the pathogenesis of metabolic diseases such as hyperlipidemia, nonalcoholic fatty liver disease (NAFLD), and type 2 diabetes (T2D). The underlying mechanisms linking obesity to metabolic diseases are still less understandable. METHODS: Previously, we screened a group of spontaneously obese rhesus monkeys. Here, we performed a plasma lipidomic analysis of normal and obese monkeys using gas chromatography/mass spectroscopy (GC/MS) and ultra-high performance liquid chromatography/mass spectroscopy (UPLC/MS). RESULTS: In total, 143 lipid species were identified, quantified, and classified into free fatty acids (FFA), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidylglycerol (PG), lysophosphatidylcholine (LPC), lysophosphatidic acid (LPA), and sphingomyelin (SM). Data analysis showed that the obese monkeys had increased levels of fatty acids palmitoleic acid (C16:1) and arachidonic acid (C20:4), FFA especially palmitic acid (C16:0), as well as certain PC species and SM species. Surprisingly, the plasma level of LPA-C16:0 was approximately four-fold greater in the obese monkeys. Conversely, the levels of most PE species were obviously reduced in the obese monkeys. CONCLUSION: Collectively, our work suggests that lipids such as FFA C16:0 and 16:0-LPA may be potential candidates for the diagnosis and study of obesity-related diseases.

A preliminary study of bipolar disorder type I by mass spectrometry-based serum lipidomics.

The present study aimed at investigating possible alterations in the serum lipid profile of euthymic patients with bipolar disorder type I (BD) compared to healthy controls (HC). Thirty-five individuals from both genders were recruited, with 14 diagnosed and treated as BD patients (BD group) and 21 healthy subjects (HC group). Clinical assessment was based on the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I), Young Mania Rating Scale (YMRS), and 17-items of Hamilton Depression Rating Scale (HDRS-17) data, which were used to confirm diagnosis, to verify psychiatric comorbidities, and to estimate the severity of manic and depressive symptoms. Ultra-high performance liquid chromatography (UHPLC) coupled to high resolution mass spectrometry (HRMS) was applied to analyze the lipids extracted from all serum samples from both studied groups. In this pioneer and exploratory study, we observed different serum lipid profiles for BD and HC groups, especially regarding glycerophospholipid, glycerolipid, and sphingolipid distribution. Multivariate statistical analyses indicated that 121 lipids were significantly different between BD and HC. Phosphatidylinositols were identified as the most altered lipids in BD patient sera. The results of this preliminary study reinforce the role of lipid abnormalities in BD and offer additional methodological possibilities for investigation in the field.

Changes in Lipids and Inflammatory Markers after Consuming Diets High in Red Meat or Dairy for Four Weeks.

There is a body of evidence linking inflammation, altered lipid metabolism, and insulin resistance. Our previous research found that insulin sensitivity decreased after a four-week diet high in dairy compared to a control diet and to one high in red meat. Our aim was to determine whether a relationship exists between changes in insulin sensitivity and inflammatory biomarkers, or with lipid species. Fasting Tumor Necrosis Factor alpha (TNF-α), Tumor Necrosis Factor Receptor II (sTNF-RII), C-reactive protein (CRP), and lipids were measured at the end of each diet. TNF-α and the ratio TNF-α/sTNF-RII were not different between diets and TNF-α, sTNF-RII, or the ratio TNF-α/sTNF-RII showed no association with homeostasis model assessment-estimated insulin resistance (HOMA-IR). A number of phosphatidylethanolamine (PE) and phosphatidylinositol (PI) species differed between dairy and red meat and dairy and control diets, as did many phosphatidylcholine (PC) species and cholesteryl ester (CE) 14:0, CE15:0, lysophosphatidylcholine (LPC) 14:0, and LPC15:0. None had a significant relationship (p = 0.001 or better) with log homeostasis model assessment-estimated insulin resistance (HOMA-IR), although LPC14:0 had the strongest relationship (p = 0.004) and may be the main mediator of the effect of dairy on insulin sensitivity. LPC14:0 and the whole LPC class were correlated with CRP. The correlations between dietary change and the minor plasma phospholipids PI32:1 and PE32:1 are novel and may reflect significant changes in membrane composition. Inflammatory markers were not altered by changes in protein source while the correlation of LPC with CRP confirms a relationship between changes in lipid profile and inflammation.

Serum phosphatidylinositol as a biomarker for bipolar disorder liability.

OBJECTIVES: Individuals with bipolar disorder (BPD) exhibit alterations in their phospholipid levels. It is unclear whether these alterations are a secondary consequence of illness state, or if phospholipids and illness risk overlap genetically. If the latter were true, then phospholipids might provide key insights into the pathophysiology of the illness. Therefore, we rank-ordered phospholipid classes by their genetic overlap with BPD risk in order to establish which class might be most informative in terms of increasing our understanding of illness pathophysiology. METHODS: Analyses were conducted in a sample of 558 individuals, unselected for BPD, from 38 extended pedigrees (average family size=14.79, range=2-82). We calculated a coefficient of relatedness for all family members of nine individuals with BPD in the sample (N=185); this coefficient was set to be zero in unrelated individuals (N=373). Then, under an endophenotype ranking value (ERV) approach, this scalar index was tested against 13 serum-based phospholipid concentrations in order to rank-order lipid classes by their respective overlap with BPD risk. RESULTS: The phosphatidylinositol class was significantly heritable (h2 =0.26, P=6.71 × 10-05 ). It was the top-ranked class, and was significantly associated with BPD risk after correction for multiple testing (ß=-1.18, P=2.10 × 10-03 , ERV=0.49). CONCLUSIONS: We identified a peripheral biomarker, serum-based phosphatidylinositol, which exhibits a significant association with BPD risk. Therefore, given that phosphatidylinositol and BPD risk share partially common etiology, it seems that this lipid class warrants further investigation, not only in terms of treatment, but also as a promising diagnostic and risk marker.

Serum metabolomic signatures discriminate early liver inflammation and fibrosis stages in patients with chronic hepatitis B.

Chronic HBV (CHB) infected patients with intermediate necroinflammation and fibrosis are recommended to receive antiviral treatment. However, other than liver biopsy, there is a lack of sensitive and specific objective method to determine the necroinflammation and fibrosis stages in CHB patients. This study aims to identify unique serum metabolomic profile associated with histological progression in CHB patients and to develop novel metabolite biomarker panels for early CHB detection and stratification. A comprehensive metabolomic profiling method was established to compare serum samples collected from health donor (n = 67), patients with mild (G < 2 and S < 2, CHB1, n = 52) or intermediate (G ≥ 2 or S ≥ 2, CHB2, n = 36) necroinflammation and fibrosis. Multivariate models were developed to differentiate CHB1 and CHB2 from controls. A set of CHB-associated biomarkers was identified, including lysophosphatidylcholines, phosphatidylcholines, phosphatidylinositol, phosphatidylserine, and bile acid metabolism products. Stratification of CHB1 and CHB2 patients by a simple logistic index, the PIPSindex, based on phosphatidylinositol (PI) and phosphatidylserine (PS), was achieved with an AUC of 0.961, which outperformed all currently available markers. A panel of serum metabolites that differentiate health control, CHB1 and CHB2 patients has been identified. The proposed metabolomic biosignature has the potential to be used as indicator for antiviral treatment for CHB management.

Phospholipid analysis in sera of horses with allergic dermatitis and in matched healthy controls.

BACKGROUND: Lipids have become an important target for searching new biomarkers typical of different autoimmune and allergic diseases. The most common allergic dermatitis of the horse is related to stings of insects and is known as insect bite hypersensitivity (IBH) or summer eczema, referring to its recurrence during the summer months. This intense pruritus has certain similarities with atopic dermatitis of humans. The treatment of IBH is difficult and therefore new strategies for therapy are needed. Autoserum therapy based on the use of serum phospholipids has recently been introduced for horses. So far, serum lipids relating to these allergic disorders have been poorly determined. The main aim of this study was to analyse phospholipid profiles in the sera of horses with allergic dermatitis and in their healthy controls and to further assess whether these lipid profiles change according to the clinical status after therapy. METHODS: Sera were collected from 10 horses with allergic dermatitis and from 10 matched healthy controls both before and 4 weeks after the therapy of the affected horses. Eczema horses were treated with an autogenous preparation made from a horse's own serum and used for oral medication. Samples were analysed for their phospholipid content by liquid chromatography coupled to a triple-quadrupole mass spectrometer (LC-MS). Data of phospholipid concentrations between the groups and over the time were analysed by using the Friedman test. Correlations between the change of concentrations and the clinical status were assessed by Spearman's rank correlation test. RESULTS: The major phospholipid classes detected were phosphatidylcholine (PC), sphingomyelin (SM), phosphatidylinositol (PI) and phosphatidylethanolamine (PE). Eczema horses had significantly lower total concentrations of PC (p < 0.0001) and SM (p = 0.0115) than their healthy controls. After a 4-week therapy, no significant differences were found between the groups. Changes in SM concentrations correlated significantly with alterations in clinical signs (p = 0.0047). CONCLUSIONS: Horses with allergic dermatitis have an altered phospholipid profile in their sera as compared with healthy horses and these profiles seem to change according to their clinical status. Sphingomyelin seems to have an active role in the course of equine insect bite hypersensitivity.

Omega-3/omega-6 fatty acid ratios in different phospholipid classes and depressive symptoms in coronary artery disease patients.

Depressive symptoms are highly incident among coronary artery disease (CAD) patients and increase mortality. Reduced ratios of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (omega-3 fatty acids) to arachidonic acid (AA, omega-6 fatty acid) concentrations have been linked with depressive symptoms in CAD. It remains unclear whether depressive symptoms are differentially associated with that ratio in different phospholipid classes, and this may have mechanistic implications. This study investigated associations between depressive symptoms in CAD patients and the EPA+DHA to AA ratio in the major phospholipid classes. This was a cross-sectional study of stable CAD patients. Sociodemographic, medical, medication, and cardiopulmonary fitness data were collected from each patient. Each patient was assessed for depressive symptoms using the 17-item Hamilton Depression Rating Scale (HAM-D). The percentage of EPA, DHA, and AA in each erythrocyte phospholipid class was determined using gas chromatography from fasting blood. Relationships between EPA+DHA to AA ratios and depressive symptoms were assessed using linear regression and were corrected for multiple comparisons. Seventy-six CAD patients were included (age=61.9 ± 8.5, 74% male, HAM-D=7.2 ± 5.9). In a backward elimination linear regression model, lower EPA+DHA to AA in erythrocyte phosphatidylinositol (B=-12.71, ß=-0.33, p<.01) and sphingomyelin (B=-2.52, ß=-0.37, p<.01) was associated with greater depressive symptom severity, independently of other known predictors. Other phospholipid classes were not associated with depressive symptoms. In conclusion, the relationship between EPA+DHA to AA ratios and depressive symptoms in CAD may not be consistent across phospholipid classes. Continued investigation of these potentially differential relationships may clarify underlying disease mechanisms.

Alterations of plasma glycerophospholipid and sphingolipid species in male alcohol-dependent patients.

BACKGROUND: Alcohol abuse is a major risk factor for somatic and neuropsychiatric diseases. Despite their potential clinical importance, little is known about the alterations of plasma glycerophospholipid (GPL) and sphingolipid (SPL) species associated with alcohol abuse. METHODS: Plasma GPL and SPL species were quantified using electrospray ionization tandem mass spectrometry in samples from 23 male alcohol-dependent patients before and after detoxification, as well as from 20 healthy male controls. RESULTS: A comparison of alcohol-dependent patients with controls revealed higher phosphatidylcholine (PC; P-value=0.008) and phosphatidylinositol (PI; P-value=0.001) concentrations in patients before detoxification, and higher PI (P-value=0.001) and phosphatidylethanolamine (PE)-based plasmalogen (PE P; P-value=0.003) concentrations after detoxification. Lysophosphatidylcholines (LPC) were increased by acute intoxication (P-value=0.002). Sphingomyelin (SM) concentration increased during detoxification (P-value=0.011). The concentration of SM 23:0 was lower in patients (P-value=2.79×10(-5)), and the concentrations of ceramide Cer d18:1/16:0 and Cer d18:1/18:0 were higher in patients (P-value=2.45×10(-5) and 3.73×10(-5)). Activity of lysosomal acid sphingomyelinase (ASM) in patients correlated positively with the concentrations of eight LPC species, while activity of secreted ASM was inversely correlated with several PE, PI and PC species, and positively correlated with the molar ratio of PC to SM (Pearson's r=-0.432; P-value=0.039). CONCLUSION: Plasma concentrations of numerous GPL and SPL species were altered in alcohol-dependent patients. These molecules might serve as potential biomarkers to improve the diagnosis of patients and to indicate health risks associated with alcohol abuse. Our study further indicates that there are strong interactions between plasma GPL concentrations and SPL metabolism.

Comprehensive lipid profiling of plasma in patients with benign breast tumor and breast cancer reveals novel biomarkers.

Abnormal lipid metabolism is a common feature in most solid tumors, and occurs in early stages of the tumor progression. As benign breast tumor is different from malignant tumor of breast cancer, it is particularly important to take benign breast tumor into consideration when investigating cancer biomarkers. In this study, by using a normal-phase/reversed-phase two-dimensional liquid chromatography-mass spectrometry (NP/RP 2D LC-MS) method, we conducted comprehensive lipid profiling in human plasma obtained from six benign breast tumor patients and five breast cancer patients, as well as nine healthy controls. As a result, 512 lipid species were successfully identified. Principal component analysis allowed clear separation of the three groups. Quantitative analysis revealed that many lipid contents were similar in benign and malignant breast tumors compared with controls, and these were proposed as potential breast tumor biomarkers other than breast cancer biomarkers. Two phosphatidylinositol (PI) species, including PI (16:0/16:1) and PI (18:0/20:4), could differentiate between benign and malignant breast tumors, as well as breast cancer patients and healthy controls, indicating that they could be utilized as potential breast cancer biomarkers. In addition, PI (16:0/18:1), phosphatidylglycerol (36:3), and glucosylceramide (d18:1/15:1) were demonstrated to be potential biomarkers to evaluate the level of malignancy of breast tumor. Taken together, our results indicate the usefulness of lipid profiling in the discrimination between patients with breast cancer and non-carcinoma lesions, which might provide assistance in clinical diagnosis.

Plasma phospholipids identify antecedent memory impairment in older adults.

Alzheimer's disease causes a progressive dementia that currently affects over 35 million individuals worldwide and is expected to affect 115 million by 2050 (ref. 1). There are no cures or disease-modifying therapies, and this may be due to our inability to detect the disease before it has progressed to produce evident memory loss and functional decline. Biomarkers of preclinical disease will be critical to the development of disease-modifying or even preventative therapies. Unfortunately, current biomarkers for early disease, including cerebrospinal fluid tau and amyloid-ß levels, structural and functional magnetic resonance imaging and the recent use of brain amyloid imaging or inflammaging, are limited because they are either invasive, time-consuming or expensive. Blood-based biomarkers may be a more attractive option, but none can currently detect preclinical Alzheimer's disease with the required sensitivity and specificity. Herein, we describe our lipidomic approach to detecting preclinical Alzheimer's disease in a group of cognitively normal older adults. We discovered and validated a set of ten lipids from peripheral blood that predicted phenoconversion to either amnestic mild cognitive impairment or Alzheimer's disease within a 2-3 year timeframe with over 90% accuracy. This biomarker panel, reflecting cell membrane integrity, may be sensitive to early neurodegeneration of preclinical Alzheimer's disease.

Lipidomic analysis of serum from high fat diet induced obese mice.

Lipid metabolites regulate fatty acid and glucose homeostasis. The intention of the current study is to identify circulating lipid species, which are altered in rodent obesity and strongly correlate with the classically measured metabolites glucose, triglycerides, and cholesterol. Mice fed a high fat diet (HFD) for 14 weeks have increased body weight and fasting glucose. Serum triglycerides are not altered, while cholesterol tends to be increased. Accordingly, major cholesteryl ester (CE) species and free cholesterol are not significantly raised in obesity while minor metabolites, including CE 20:3 and CE 18:3, are increased or reduced, respectively. Distinct sphingomyelin (SM) species are elevated while ceramides are not raised. Phosphatidylinositol (PI) species, including PI 34:1, are raised while others are decreased. PI 34:1 strongly correlates with fasting glucose and proinsulin levels. Phosphatidylcholine (PC) 26:0, 40:2, and 40:5, which are induced in obesity, correlate with cholesterol. PC 38:4 and PC 40:6 are also raised in fat fed mice and positively correlate with fasting glucose. Lysophosphatidylcholine (LPC) species are also changed in obesity and the already shown reduction of LPC 16:1 has been confirmed. LPC 22:4, which is increased, correlates with serum cholesterol. The data indicate that circulating levels of various lipid species are changed in the obesity model studied and some of them are strongly associated with classically measured metabolites.

[The content of phosphoinositides and their metabolites in blood components in patients with chronic generalized periodontitis].

The aim of the study was to evaluate the content of phosphoinositides (PI) and their metabolites in blood components to reveal the diagnostic value of these in patients with chronic generalized periodontitis. Forty-five patients (30 female and 15 male aged 21-55) with chronic generalized periodontitis, as well as 30 patients with no signs of periodontal disease were included in the study. The PI content differ significantly between the groups thus making it possible using them as diagnostic and follow-up markers.

Hemocompatibility of liposomes loaded with lipophilic prodrugs of methotrexate and melphalan in the lipid bilayer.

A panel of in vitro tests intended for evaluation of the nano-sized drug delivery systems' compliance with human blood was applied to liposomal formulations of anticancer lipophilic prodrugs incorporated into the lipid bilayer. Liposomes on the basis of natural phosphatidylcholine (PC) and phosphatidylinositol (PI), 8:1 (mol) were loaded with 10 mol% of either methotrexate or melphalan 1,2-dioleoylglyceride esters (MTX-DOG and Mlph-DOG respectively) and either decorated with 2 mol% of sialyl Lewis X/A (SiaLe(X/A)) tetrasaccharide ligand or not. Hemolysis rate, red blood cells and platelets integrity and size distribution, complement (C) activation, and coagulation cascade functioning were analyzed upon the material incubation with whole blood. Both formulations were negatively charged with the zeta potential value being higher in the case of MTX-DOG liposomes, which also were larger than Mlph-DOG liposomes and more prone to aggregation. Accordingly, in hemocompatibility tests Mlph-DOG liposomes did not provoke any undesirable effects, while MTX-DOG liposomes induced significant C activation and abnormal coagulation times in a concentration-dependent manner. Reactivity of the liposome surface was not affected by the presence of SiaLe(X/A) or PI. Decrease in liposome loading with MTX-DOG from 10 to 2.5% resulted in lower surface charge density, smaller liposome size and considerably reduced impact on C activation and coagulation cascades.

A phospholipidomic analysis of all defined human plasma lipoproteins.

Since plasma lipoproteins contain both protein and phospholipid components, either may be involved in processes such as atherosclerosis. In this study the identification of plasma lipoprotein-associated phospholipids, which is essential for understanding these processes at the molecular level, are performed. LC-ESI/MS, LC-ESI-MS/MS and High Performance Thin Layer Chromatography (HPTLC) analysis of different lipoprotein fractions collected from pooled plasma revealed the presence of phosphatidylethanolamine (PE), phosphatidylinositol (PI), and sphingomyeline (SM) only on lipoproteins and phosphatidylcholine (PC), Lyso-PC on both lipoproteins and plasma lipoprotein free fraction (PLFF). Cardiolipin, phosphatidylglycerol (PG) and Phosphatidylserine (PS) were observed neither in the lipoprotein fractions nor in PLFF. All three approaches led to the same results regarding phospholipids occurrence in plasma lipoproteins and PLFF. A high abundancy of PE and SM was observed in VLDL and LDL fractions respectively. This study provides for the first time the knowledge about the phospholipid composition of all defined plasma lipoproteins.

Macroscopic domain formation during cooling in the platelet plasma membrane: an issue of low cholesterol content.

There has been ample debate on whether cell membranes can present macroscopic lipid domains as predicted by three-component phase diagrams obtained by fluorescence microscopy. Several groups have argued that membrane proteins and interactions with the cytoskeleton inhibit the formation of large domains. In contrast, some polarizable cells do show large regions with qualitative differences in lipid fluidity. It is important to ask more precisely, based on the current phase diagrams, under what conditions would large domains be expected to form in cells. In this work we study the thermotropic phase behavior of the platelet plasma membrane by FTIR, and compare it to a POPC/Sphingomyelin/Cholesterol model representing the outer leaflet composition. We find that this model closely reflects the platelet phase behavior. Previous work has shown that the platelet plasma membrane presents inhomogeneous distribution of DiI18:0 at 24 degrees C, but not at 37 degrees C, which suggests the formation of macroscopic lipid domains at low temperatures. We show by fluorescence microscopy, and by comparison with published phase diagrams, that the outer leaflet model system enters the macroscopic domain region only at the lower temperature. In addition, the low cholesterol content in platelets ( approximately 15 mol%), appears to be crucial for the formation of large domains during cooling.