Repeated lipoprotein apheresis and immune response: Effects on different immune cell populations.

BACKGROUND: Atherosclerosis is considered a chronic inflammation of arterial vessels with the involvement of several immune cells causing severe cardiovascular diseases. Lipoprotein apheresis (LA) improves cardiovascular conditions of patients with severely disturbed lipid metabolism. In this context, little is known about the impact of LA on various immune cell populations, especially over time. METHODS: Immune cells of 18 LA-naïve patients starting weekly LA treatment were analyzed before and after four apheresis cycles over the course of 24 weeks by flow cytometry. RESULTS AND CONCLUSIONS: An acute lowering effect of LA on T cell and natural killer (NK) cell subpopulations expressing CD69 was observed. The non-classical and intermediate monocyte subsets as well as HLA-DR+ 6-sulfo LacNAc+ monocytes were significantly reduced during the apheresis procedure. We conclude that LA has the capacity to alter various immune cell subsets. However, LA has mainly short-term effects than long-term consequences on proportions of immune cells.

Classical Xanthinuria in Nine Israeli Families and Two Isolated Cases from Germany: Molecular, Biochemical and Population Genetics Aspects.

Classical xanthinuria is a rare autosomal recessive metabolic disorder caused by variants in the XDH (type I) or MOCOS (type II) genes. Thirteen Israeli kindred (five Jewish and eight Arab) and two isolated cases from Germany were studied between the years 1997 and 2013. Four and a branch of a fifth of these families were previously described. Here, we reported the demographic, clinical, molecular and biochemical characterizations of the remaining cases. Seven out of 20 affected individuals (35%) presented with xanthinuria-related symptoms of varied severity. Among the 10 distinct variants identified, six were novel: c.449G>T (p.(Cys150Phe)), c.1434G>A (p.(Trp478*)), c.1871C>G (p.(Ser624*)) and c.913del (p.(Leu305fs*1)) in the XDH gene and c.1046C>T (p.(Thr349Ileu)) and c.1771C>T (p.(Pro591Ser)) in the MOCOS gene. Heterologous protein expression studies revealed that the p.Cys150Phe variant within the Fe/S-I cluster-binding site impairs XDH biogenesis, the p.Thr349Ileu variant in the NifS-like domain of MOCOS affects protein stability and cysteine desulfurase activity, while the p.Pro591Ser and a previously described p.Arg776Cys variant in the C-terminal domain affect Molybdenum cofactor binding. Based on the results of haplotype analyses and historical genealogy findings, the potential dispersion of the identified variants is discussed. As far as we are aware, this is the largest cohort of xanthinuria cases described so far, substantially expanding the repertoire of pathogenic variants, characterizing structurally and functionally essential amino acid residues in the XDH and MOCOS proteins and addressing the population genetic aspects of classical xanthinuria.

Short- and long-term effects of lipoprotein apheresis on plasma hormones in patients with therapy-resistant dyslipidemia.

BACKGROUND AND AIMS: Lipoprotein apheresis (LA) is a highly effective method to improve the clinical and metabolic situation in patients with therapy-resistant disorders of lipid metabolism. Cholesterol is the substrate for the synthesis of all steroid hormones. If repeated massive reduction of LDL-cholesterol may interfere with human adrenal steroidogenesis, and could become clinically relevant is unknown, so far. Thus, the aim of this study was to determine possible short- and long-term effects of LA on blood plasma levels of ACTH, cortisol, aldosterone, DHEAS, renin and testosterone. METHODS: In total, 39 patients, treated with one of four LA techniques were studied: 1. Lipid Filtration (LF; n = 7), 2. Dextran Sulfate Adsorption (DSA; n = 7), 3. Membrane Filtration Optimised Novel Extracorporeal Treatment (MONET; n = 8), and 4. Direct Absorption of Lipoproteins (DALI; n = 15). Hormone levels were analyzed before and after five LA sessions with an interval of 20 weeks covering a total observation time of two years. In addition patients were comprehensively characterized by clinical and laboratory data. RESULTS: Patients treated with LA revealed an acute reduction of steroid hormones and ACTH, independent of apheresis technology but no long-term insufficiency in steroidogenesis was observed. Plasma renin levels were stable in LF patients and were highly elevated in patients under DSA, MONET and DALI apheresis throughout the observation period. CONCLUSIONS: In summary, these data suggest that although different LA techniques considerably differ in their acute effects on hormone levels during LA, they did not alter long-term hormone levels sustainably.

Long-term follow-up of circulating oxidative stress markers in patients undergoing lipoprotein apheresis by Direct Adsorption of Lipids (DALI).

OBJECTIVE: Beyond its well-established efficacy in lowering atherogenic lipids and lipoproteins, DALI (Direct Adsorption of Lipids) apheresis has been shown to have acute anti-inflammatory and endothelium-protective effects. In the present study, we investigated long-term effects of DALI procedures on circulating oxidative stress markers. METHODS: Thirteen patients involved in the study underwent regular DALI apheresis for nearly two years. At sessions 1, 40 and 80 conventional lipid status and changes of systemic oxidative stress markers (oxidized LDL, anti-oxidized LDL antibodies, advanced oxidation protein products (AOPP), and myeloperoxidase (MPO)) were examined. RESULTS: DALI procedure efficiently reduced atherogenic lipids/lipoproteins. On day three after apheresis lipid parameters returned to pre-apheresis values. They showed no tendency to increase or to decrease over time. No significant differences were found between 1st, 40th and 80th sessions. In a similar way, levels of oxidative stress biomarkers acutely decreased after apheresis sessions and rebounded on day three after apheresis. No significant differences were observed between sessions 1, 40, and 80. CONCLUSION: DALI apheresis repeatedly decreases atherogenic lipid/lipoprotein profile and oxidative stress biomarker levels during each session. Among all investigated parameters no longitudinal effects over two years could be observed.

Lipidomic Changes in Skeletal Muscle in Patients after Biliopancreatic Diversion.

The mechanisms behind the fast improvements of insulin sensitivity and release of the diabetic metabolic state after bariatric surgery are still not completely understood. To further elucidate the effects on the individual cellular level, we applied mass spectrometry to investigate the changes in the lipidomic profile of skeletal muscle cells before and after biliopancreatic diversion in six patients. We found a decrease in lipid storage species, mainly triacylglycerides (e. g., TAG 52:2 from 19.84 to 13.26 mol%; p=0.028), and an increase in structural and signaling lipids, including phosphatidylcholines [PC 36:2 (18:1/18:1) from 0.12 to 0.65 mol%; p=0.046], phosphatidylinositols (PI 36:2 from 0.008 to 0.039 mol%; p=0.046), and cardiolipins (CL 72:8 from 0.16 to 1.22 mol%; p=0.043). The proportional increase in structural lipids was directly and the decrease in TAGs was inversely correlated to improved post-operative insulin sensitivity, measured by euglycemic hyperinsulinemic clamp. Thus, short-term recovery of insulin sensitivity after biliopancreatic diversion may, beside gut hormonal adaptation, mechanical factors, shifts in the gut microbiome, and changes in bile acid and phospholipid metabolism, additionally be attributed to a metabolic recovery of skeletal muscle cells, reflected by normalization of the cellular lipidomic profile. Further studies are needed to investigate whether improved insulin sensitivity of skeletal muscle might be directly associated with the degradation of ectopic triglycerides, thereby reducing the reservoir of lipotoxic intermediates, which might interfere with insulin signaling and hamper mitochondrial metabolism.

Aldosterone Hypothesis for Cognitive Impairment in Diabetes Mellitus.

Increased plasma aldosterone concentration is significantly associated with dementia, which is accentuated by diabetes mellitus (DM). Angiotensin II (AngII) deteriorates cognitive function through neuronal degradation. Lipoproteins, a major source of cholesterol for aldosterone biosynthesis, undergo glycoxidative modifications in the presence of hyperglycemia. We hypothesize that there would be a pathophysiological link between diabetically-modified lipoproteins, angiotensin II, and increased plasma aldosterone concentration for induction of cognitive impairment. Glycoxidized lipoproteins produce significantly more aldosterone from AngII-sensitized adrenocortical cells compared to their native counterparts. The elucidation of signaling mechanisms revealed that modified lipoproteins follow the similar signaling mechanism like AngII for adrenocortical aldosterone release via ERK1/2 and Janus kinase-2 (Jak-2)-mediated pathways. The enhanced aldosterone release from AngII-sensitized adrenocortical cells induced by glycoxidatively modified lipoproteins may play a crucial role in cognitive dysfunction in diabetic individuals along with AngII via a prevailing mode of signaling cascade involving ERK1/2- and Jak-2-dependent pathways.

Detection of Independent Associations of Plasma Lipidomic Parameters with Insulin Sensitivity Indices Using Data Mining Methodology.

OBJECTIVE: Glucolipotoxicity is a major pathophysiological mechanism in the development of insulin resistance and type 2 diabetes mellitus (T2D). We aimed to detect subtle changes in the circulating lipid profile by shotgun lipidomics analyses and to associate them with four different insulin sensitivity indices. METHODS: The cross-sectional study comprised 90 men with a broad range of insulin sensitivity including normal glucose tolerance (NGT, n = 33), impaired glucose tolerance (IGT, n = 32) and newly detected T2D (n = 25). Prior to oral glucose challenge plasma was obtained and quantitatively analyzed for 198 lipid molecular species from 13 different lipid classes including triacylglycerls (TAGs), phosphatidylcholine plasmalogen/ether (PC O-s), sphingomyelins (SMs), and lysophosphatidylcholines (LPCs). To identify a lipidomic signature of individual insulin sensitivity we applied three data mining approaches, namely least absolute shrinkage and selection operator (LASSO), Support Vector Regression (SVR) and Random Forests (RF) for the following insulin sensitivity indices: homeostasis model of insulin resistance (HOMA-IR), glucose insulin sensitivity index (GSI), insulin sensitivity index (ISI), and disposition index (DI). The LASSO procedure offers a high prediction accuracy and and an easier interpretability than SVR and RF. RESULTS: After LASSO selection, the plasma lipidome explained 3% (DI) to maximal 53% (HOMA-IR) variability of the sensitivity indexes. Among the lipid species with the highest positive LASSO regression coefficient were TAG 54:2 (HOMA-IR), PC O- 32:0 (GSI), and SM 40:3:1 (ISI). The highest negative regression coefficient was obtained for LPC 22:5 (HOMA-IR), TAG 51:1 (GSI), and TAG 58:6 (ISI). CONCLUSION: Although a substantial part of lipid molecular species showed a significant correlation with insulin sensitivity indices we were able to identify a limited number of lipid metabolites of particular importance based on the LASSO approach. These few selected lipids with the closest connection to sensitivity indices may help to further improve disease risk prediction and disease and therapy monitoring.

Gender, Contraceptives and Individual Metabolic Predisposition Shape a Healthy Plasma Lipidome.

Lipidomics of human blood plasma is an emerging biomarker discovery approach that compares lipid profiles under pathological and physiologically normal conditions, but how a healthy lipidome varies within the population is poorly understood. By quantifying 281 molecular species from 27 major lipid classes in the plasma of 71 healthy young Caucasians whose 35 clinical blood test and anthropometric indices matched the medical norm, we provided a comprehensive, expandable and clinically relevant resource of reference molar concentrations of individual lipids. We established that gender is a major lipidomic factor, whose impact is strongly enhanced by hormonal contraceptives and mediated by sex hormone-binding globulin. In lipidomics epidemiological studies should avoid mixed-gender cohorts and females taking hormonal contraceptives should be considered as a separate sub-cohort. Within a gender-restricted cohort lipidomics revealed a compositional signature that indicates the predisposition towards an early development of metabolic syndrome in ca. 25% of healthy male individuals suggesting a healthy plasma lipidome as resource for early biomarker discovery.

Association between systemic oxidative stress and insulin resistance/sensitivity indices - the PREDIAS study.

OBJECTIVE: Systemic oxidative stress has been causally related to insulin resistance and the subsequent development of type 2 diabetes mellitus (T2D). We investigated associations between circulating oxidative stress markers and different surrogate indexes of insulin sensitivity/resistance. PATIENTS: Cross-sectional data were obtained from 1183 subjects with normal glucose tolerance (NGT), 280 subjects with impaired glucose tolerance (IGT) and 69 newly detected T2D individuals entering the PREDIAS (prevention of diabetes) study. MEASUREMENTS: Following oral glucose tolerance test, five different insulin sensitivity/resistance indices were estimated: homoeostasis model of insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), early phase insulin release (EPIR), insulin sensitivity index (ISI) and disposition index (DI). Additionally, circulating phagocyte generation of reactive oxygen species (ROS) and plasma total antioxidant capacity (TAC) was measured. RESULTS: After adjustment for five covariates, HOMA-IR was significantly increased in IGT and T2D subjects when compared to NGT subjects (P = 0·000). QUICKI (P = 0·000), ISI (P = 0·000), EPIR (0·005/0·012) and DI (P = 0·000) were significantly attenuated in IGT and T2D. The prevalence of IGT and T2D individuals increased with increasing ROS generation and TAC tertiles. Increased systemic ROS generation was paralleled by increased HOMA-IR (P < 0·001, tertile 1/T1/vs tertile 3/T3/), decreased QUICKI (P < 0·001, T1 vs T3) and decreased ISI (P < 0·05, T1 vs T3). A similar tendency for indices was observed when comparing TAC tertiles: increase in HOMA-IR, decrease in QUICKI and ISI (P < 0·001, T1 vs T3 each). EPIR and DI did not differ significantly across ROS generation and TAC tertiles. CONCLUSIONS: Systemic oxidative stress is associated with elevated insulin resistance index HOMA-IR, and decreased insulin sensitivity surrogates QUICKI and ISI.

Long-term therapeutic efficacy of lipoprotein apheresis on circulating oxidative stress parameters--A comparison of two different apheresis techniques.

BACKGROUND: A chronic lipoprotein apheresis therapy leads to an expressed reduction in the incidence of cardiovascular events in high-risk patients. In addition to the elimination of atherogenic lipoproteins such as LDL and lipoprotein(a), an antioxidative effect of lipoprotein apheresis has been suspected. OBJECTIVES AND METHODS: We investigated long-term biochemical effects in sixteen patients undergoing lipoprotein apheresis - lipid filtration (LF, n = 7) or dextran sulfate adsorption (DSA, n = 9). Systemic oxidative stress markers (blood phagocyte chemiluminescence, levels of oxidized LDL and antioxLDL antibodies) were examined at the 1st, 40th and 80th apheresis sessions. RESULTS: In DSA patients, the 80th apheresis session was associated with significantly higher LDL cholesterol removal and lower HDL cholesterol deprivation as compared to LF patients. In contrast to LF patients, DSA patients showed a long-term progressive decrease in circulating oxidant generating activity as evaluated by whole blood chemiluminescence (p < 0.05). Moreover, a single LF apheresis session was associated with higher systemic generation of reactive oxygen species over time. CONCLUSION: Compared to LF, long-term DSA apheresis is associated with a gradual reduction of circulating oxidative burden and may be considered a beneficial molecular mechanism of this technique.

Increasing plasma lysophosphatidylcholine levels in patients with regular dextran sulfate lipoprotein apheresis.

OBJECTIVES: Previously we found a highly significant increase of phosphatidylethanolamines (PE) in response to acute lipoprotein apheresis (LA) with whole blood dextran sulfate adsorption (DSA) in contrast to the overall tendency of reduction of lipid metabolites of all lipid classes in post-apheresis plasma. Therefore, the aim of the present study was to analyze long-term modifications of the plasma lipidomic profile in patients with repeated DSA apheresis. METHODS: Nine patients weekly treated with DSA were followed for 40 weeks. Pre- and post-apheresis levels of routine lipid parameters and lipidomic profiles of five apheresis sessions were assessed. RESULTS: The main finding of the present study was a progressive increase of pre- and post-apheresis plasma lysophosphatidylcholine (LPC) levels, which doubled in concentration at the end of the 40 week observation period. LPC metabolites which mainly contributed to this increase were LPC 20:4 > 18:0 > 18:1 > 16:0 > 20:3 > 18:2. CONCLUSION: These data indicate that long-term application of DSA technology may be associated with a continuous increase in LPC levels. Possible pro- or anti-atherogenic consequences should be elucidated in further studies.

Quantitative profiling of endocannabinoids in lipoproteins by LC-MS/MS.

Endocannabinoids belong to a diverse family of endogenous lipid bioregulators acting as physiological ligands of cannabinoid receptor type 1 and cannabinoid receptor type 2 in the central and peripheral nervous system. They are also present in nmol L(-1) concentrations in human blood plasma; however, their association with possible molecular carriers remains poorly characterized. Here we report on the quantification of 46 endogenous molecular species from five major classes of endocannabinoids and endocannabinoid-related compounds in three lipoprotein fractions of human blood plasma: VLDL, LDL, HDL, and in the plasma lipoprotein-free fraction. Although sizable quantities of endocannabinoid-related molecules are associated with lipoproteins, we identified the lipoprotein-free fraction as a major carrier of endocannabinoids in blood circulation with the exception of 2-acylglycerols, which are markedly abundant in VLDL.

Lipidomic profiling at the interface of metabolic surgery and cardiovascular disease.

Bariatric surgery has helped patients attain not only significant and sustained weight loss but has also proved to be an effective means of mitigating or reversing various obesity-related comorbidities. The impressive rates of remission or resolution of type 2 diabetes mellitus (T2D) following bariatric surgery are well documented and have rightly received great attention. Less understood are the effects of bariatric surgery on cardiovascular disease (CVD) and its underlying risk factors. Thanks to the availability of increasingly sensitive laboratory tools, the emerging science of lipidomics and metagenomics is poised to offer significant contributions to our understanding of metabolically induced vascular diseases. They are set to identify novel mechanisms explaining how the varied approaches of bariatric surgery produce the remarkable improvements in multiple organs observed during patient follow-up. This article reviews recent and novel findings in patients through the lens of lipidomics with an emphasis on CVD.

Stimulation of phagocyte adhesion to endothelial cells by modified VLDL and HDL requires scavenger receptor BI.

Hyperglycemia- and oxidative stress-induced modification of circulating lipoproteins is being increasingly recognized as an important pathogenetic factor for diabetic cardiovascular damages. This study was designed to investigate the impact of modified very low-density lipoprotein and high-density lipoprotein on phagocyte adhesion to endothelial cells and the involvement of scavenger receptor class B type 1 (SR-BI) in this process. Native lipoproteins were isolated by density gradient ultracentrifugation and in vitro glycoxidative or oxidative modification was performed in the presence of glucose or sodium hypochlorite, respectively. One hour co-incubation experiments with lipoproteins, freshly prepared polymorphonuclear leukocytes (PMN), and venous endothelial cells (HUVEC) were performed in the presence or absence of different scavenger receptors and signal transduction inhibitors. PMN adhesion to HUVEC was quantified fluorimetrically. We demonstrated that oxidized and glycoxidized lipoproteins promote adhesion of PMN to HUVEC from 1.5- to 2.5-fold with oxidized lipoproteins having the greatest effect. Treatment with the highly specific SR-BI inhibitor, BLT-1 produced substantial reduction of lipoprotein-induced adhesion to endothelial cells. Native and modified lipoproteins recruited extracellular signal-regulated kinase (ERK 1/2), p38 mitogen-activated protein kinase, and Janus kinase 2 as downstream signaling pathways for adhesion. From this study, it could be concluded that modification of lipoproteins plays a crucial role in atherosclerotic progression and SR-BI may be considered as a potential therapeutic target for the prevention of diabetic cardiovascular complications.

Modified high-density lipoprotein modulates aldosterone release through scavenger receptors via extra cellular signal-regulated kinase and Janus kinase-dependent pathways.

Patients with type 2 diabetes (T2D) manifest significant abnormalities in lipoprotein structure and function. The deleterious impact of oxidative and glycoxidative modifications on HDL-mediated atheroprotective, antiinflammatory, and antioxidative phenomena has been well established. However, the biological effects of modified HDL on adrenal steroidogenesis-which could reveal a pathophysiological link to the overactivity of the renin-angiotensin-aldosterone system and its adverse cardiovascular consequences often observed in T2D-are not well delineated. We studied the role of modified HDL on aldosterone release from adrenocortical carcinoma cells (NCI-H295R). In vitro modifications of native HDL were performed in the presence of glucose for glycoxidized HDL (glycoxHDL) and sodium hypochlorite for oxidized HDL. Angiotensin II (AngII)-sensitized H295R cells were treated with lipoproteins for 24 h, and supernatant was used to measure aldosterone release. Both native and modified HDL augmented the steroid release from AngII-sensitized cells, with glycoxHDL having the greatest impact. Both the modified forms of HDL induced a significant increase in scavenger receptor expression and employed protein kinase C as well as extracellular signal-regulated kinase as downstream effectors of aldosterone release. Native HDL and modified HDL required Janus kinase-2 for combating increased demand in steroidogenesis. Therefore, our data support the hypothesis that diabetes-induced modification of HDL may promote adrenocortical aldosterone secretion via different signal transduction pathways. This significant influence on multiple signaling mechanisms could be targeted for future research to implement novel therapeutic trials.

Very-low-density lipoprotein mediates transcriptional regulation of aldosterone synthase in human adrenocortical cells through multiple signaling pathways.

Diabetic dyslipidemia is characterized by increased circulatory very-low-density lipoprotein (VLDL) levels. Aldosterone, apart from its role in fluid and electrolyte homeostasis, has also been implicated in insulin resistance and myocardial fibrosis. The impact of VLDL as a potential risk factor for aldosterone-mediated cardiovascular injury in diabetes mellitus, however, remains to be investigated. We have therefore studied native and modified VLDL-mediated steroidogenesis and its underlying molecular mechanisms in human adrenocortical carcinoma cells, NCI H295R. Native VLDL (natVLDL), isolated from healthy volunteers, was subjected to in vitro modification with glucose (200 mmol/l) or sodium hypochlorite (1.5 mmol/l) for preparation of glycoxidized and oxidized VLDL, respectively. VLDL treatment induced steroidogenesis in both a concentration- and time-dependent manner. Native and glycoxidized VLDL (50 µg/ml) were almost two-fold more potent in adrenocortical aldosterone release than angiotensin II (100 nmol/l). These forms of VLDL significantly augmented transcriptional regulation of aldosterone synthase (Cyp11B2), partially through scavenger receptor class B type I, as evident from the effect of BLT-1. In contrast to glycoxidized VLDL, oxidized VLDL significantly attenuated the stimulatory effect of natVLDL on adrenocortical hormone synthesis. Moreover, treatment with specific pharmacological inhibitors (H89, U0126, AG490) provided supporting evidence that VLDL, irrespective of modification, presumably recruited PKA, ERK1/2 and Jak-2 for steroid hormone release through modulation of Cyp11B2 mRNA level. In conclusion, this study demonstrates a novel insight into intracellular mechanism of VLDL-mediated aldosterone synthesis through transcriptional regulation of steroidogenic acute regulatory protein (StAR) and Cyp11B2 expression in human adrenocortical carcinoma cell line.

Type 2 diabetes in octogenarians is associated with decreased low molecular weight adiponectin.

BACKGROUND: Adiponectin circulates in the blood in three different multimer isoforms, of which the high molecular weight form (HMW) is presumed to mediate insulin sensitivity. We examined whether adiponectin oligomer distribution is associated with aging and type 2 diabetes (T2D) in octogenarians without characteristic features of metabolic syndrome. METHODS: The study included 154 octogenarians (58 men, 96 women), 24 normoglycemic middle-aged controls (11 men, 13 women; mean age 44 years), and 33 middle-aged individuals (14 men, 19 women; mean age 55 years) with T2D. Based on oral glucose tolerance test 62 octogenarians had normal, 63 impaired glucose tolerance, and 29 octogenarians had newly detected T2D. Serum adiponectin multimer isoforms were measured after overnight fast by enzyme-linked immunosorbent assays. RESULTS: Compared to the normoglycemic middle-aged control group, male normoglycemic octogenarians revealed significantly higher total adiponectin and all adiponectin isoforms. The same was true for females with the exception of low molecular weight (LMW) adiponectin, which was not statistically higher in octogenarians. Male and female octogenarians with T2D had significantly higher levels of total, HMW, and middle molecular weight (MMW) adiponectin, but not LMW adiponectin, than middle-aged individuals with T2D. Female, but not male, octogenarians revealed significantly lower total adiponectin than normoglycemic octogenarians. Compared with normoglycemic octogenarians, male and female octogenarians with T2D were characterized by significantly lower LMW adiponectin. In male and female octogenarians, total adiponectin and all multimer isoforms were directly correlated with HDL cholesterol. LMW adiponectin in octogenarians of both sexes was inversely correlated with glucose level at 2-hour oral glucose tolerance test. CONCLUSIONS: Serum levels of total adiponectin as well as its HMW and MMW isoforms were significantly higher in octogenarians with normoglycemia or T2D than in corresponding middle-aged control groups. In male and female octogenarians without metabolic syndrome, T2D was associated with lower LMW adiponectin, while the HMW and MMW isoforms were not statistically different.

Modulation of adrenal aldosterone release by oxidative modification of low-density lipoprotein.

BACKGROUND: Serum aldosterone is a causative factor for various metabolic and cardiovascular disorders. Low-density lipoprotein (LDL) is a major cholesterol source for aldosterone steroidogenesis; however, the effect of oxidative modification of LDL on aldosterone release is not known. We studied the effect of hypochlorite-oxidized LDL (oxLDL) on adrenal aldosterone secretion. METHODS: LDL (native LDL (natLDL)) was obtained from healthy volunteers and oxidatively modified in vitro. NCI-H295R cells were stimulated with natLDL and oxLDL, and the aldosterone release was quantified by radioimmunoassay. Molecular changes were studied with western blot analysis and quantitative RT-PCR analysis. RESULTS: NatLDL and oxLDL caused dose-dependent increase in aldosterone release up to threefold. However, the stimulatory effects of modified LDL on aldosterone secretion decreased with increasing degree of LDL oxidation. 24-h incubations with natLDL, mild- and medium-oxidized LDL sensitized the adrenocortical cells to subsequent angiotensin II (Ang II) stimulations by 2.9-, 2.8-, and 2.5-folds, respectively. Heavily oxidized LDL did not sensitize the cells to Ang II stimulations to a similar extent. At the molecular level, the ERK pathway was activated within a minute by both natLDL and oxLDL; however, oxLDL showed a stronger (2.75-fold at 1 and 15 min) and longer (15 min) activation of ERK than natLDL (twofold). CONCLUSIONS: This study demonstrates the following: (i) both natLDL and hypochlorite-oxidized LDL utilize ERK pathway to mediate aldosterone release; (ii) mildly oxidized LDL sensitizes the adrenocortical cells to further stimulations by Ang II similar to natLDL that may have a role in pathological processes; (iii) extensive LDL oxidation counteracts adrenocortical aldosterone release.

Top-down lipidomics reveals ether lipid deficiency in blood plasma of hypertensive patients.

BACKGROUND: Dyslipoproteinemia, obesity and insulin resistance are integrative constituents of the metabolic syndrome and are major risk factors for hypertension. The objective of this study was to determine whether hypertension specifically affects the plasma lipidome independently and differently from the effects induced by obesity and insulin resistance. METHODOLOGY/PRINCIPAL FINDINGS: We screened the plasma lipidome of 19 men with hypertension and 51 normotensive male controls by top-down shotgun profiling on a LTQ Orbitrap hybrid mass spectrometer. The analysis encompassed 95 lipid species of 10 major lipid classes. Obesity resulted in generally higher lipid load in blood plasma, while the content of tri- and diacylglycerols increased dramatically. Insulin resistance, defined by HOMA-IR >3.5 and controlled for BMI, had little effect on the plasma lipidome. Importantly, we observed that in blood plasma of hypertensive individuals the overall content of ether lipids decreased. Ether phosphatidylcholines and ether phosphatidylethanolamines, that comprise arachidonic (20:4) and docosapentaenoic (22:5) fatty acid moieties, were specifically diminished. The content of free cholesterol also decreased, although conventional clinical lipid homeostasis indices remained unaffected. CONCLUSIONS/SIGNIFICANCE: Top-down shotgun lipidomics demonstrated that hypertension is accompanied by specific reduction of the content of ether lipids and free cholesterol that occurred independently of lipidomic alterations induced by obesity and insulin resistance. These results may form the basis for novel preventive and dietary strategies alleviating the severity of hypertension.

Prediabetic and diabetic in vivo modification of circulating low-density lipoprotein attenuates its stimulatory effect on adrenal aldosterone and cortisol secretion.

Modification of low-density lipoprotein (LDL) and abnormal aldosterone and cortisol metabolism have been implicated in the pathogenesis of type 2 diabetes (DM2) and diabetic vascular disease. Since LDL serves as a major cholesterol source for adrenal steroidogenesis, we investigated whether LDL modification in prediabetic and diabetic subjects influences adrenocortical aldosterone and cortisol release. LDL was isolated from 30 subjects with normal glucose tolerance (NGT-LDL), 30 subjects with impaired glucose tolerance (IGT-LDL), and 26 patients with DM2 (DM2-LDL). Oxidation and glycoxidation characteristics of LDL apolipoprotein B100 of each individual was assessed by gas chromatography-mass spectrometry analysis. Human adrenocortical cells (NCI-H295R) were incubated for 24 h with 100 microg/ml LDL and after removal of supernatants stimulated for a further 24 h with angiotensin II (AngII). In supernatants, aldosterone and cortisol secretion was measured. IGT-LDL and DM2-LDL were substantially more modified than NGT-LDL. Each of the five measured oxidation/glycoxidation markers was significantly positively associated with glycemic control, measured as HbA(1c). LDL from all subjects stimulated both the basal and AngII-induced aldosterone and cortisol release from adrenocortical cells. However, hormone secretion was significantly inversely related to the degree of LDL oxidation/glycoxidation. We conclude that LDL modifications in IGT and DM2 subjects may have significant clinical benefits by counteracting prediabetic and diabetic overactivity of the renin-angiotensin-aldosterone system and enhanced cortisol generation.