Sphingolipid and Trimethylamine-N-Oxide (TMAO) Levels in Women with Obesity after Combined Physical Training.

Obesity causes metabolic changes, such as the development of cardiovascular diseases. Moreover, physical exercise promotes protection against these diseases. Thus, the objective of the present study was to evaluate whether combined physical training can improve the metabolic system of women with obesity, reducing plasma concentrations of trimethylamine N-oxide (TMAO) and sphingolipids, regardless of weight loss. Fourteen obese women (BMI 30-40 kg/m2), aged 20-40 years, sedentary, were submitted to 8 weeks of combined physical training (strength and aerobic exercises). The training was performed three times/week, 55 min/session, at 75-90% maximum heart rate. All participants were evaluated pre- and post-exercise intervention, and their body composition, plasma TMAO, creatinine, lipid profile, and sphingolipid concentrations were recorded. Maximum oxygen consumption (VO2max), Speed lactate threshold 1 (SpeedLT1), and Speed lactate threshold 2 (SpeedLT2) evaluated physical performance. Results: After combined exercise, it did not change body composition, but TMAO, total cholesterol, and sphingolipid concentrations significantly decreased (p < 0.05). There was an increase in physical performance by improving VO2max, SpeedLT1, and SpeedLT2 (p < 0.05). The combined physical exercise could induce cardiovascular risk protection by decreasing TMAO in obese women, parallel to physical performance improvement, independent of weight loss.

Maternal Stress during Pregnancy in Mice Induces Sex-Dependent Behavioral Alterations in Offspring along with Impaired Serotonin and Kynurenine Pathways of Tryptophan Metabolism.

Maternal stress during pregnancy results in increased risk of developing psychiatric disorders in the offspring including anxiety, depression, schizophrenia, and autism. However, the mechanisms underlying this disease susceptibility remain largely to be determined. In this study, the involvement of the serotonin (5-HT) and kynurenine (KYN) pathways of tryptophan metabolism on the behavioral deficits induced by maternal stress during the late phase of gestation in mice was investigated. Adult offspring born to control or restraint-stressed dams were exposed to the elevated plus-maze and tail suspension tests. Metabolites of the KYN and 5-HT pathways were measured in the hippocampus and brainstem by ultra-performance liquid chromatography tandem mass spectrometry. Female, but not male, prenatally stressed (PNS) offspring displayed a depressive-like phenotype, mainly when in proestrus/diestrus, along with reduced hippocampal 5-HT levels and high 5-HT turnover rate in the hippocampus and brainstem. In contrast, male PNS mice showed enhanced anxiety-like behaviors and higher hippocampal and brainstem quinolinic acid levels compared to male offspring born to nonstressed dams. These results indicate that maternal stress affects the behavior and brain metabolism of tryptophan in the offspring in a sex-dependent manner and suggest that alterations in both the 5-HT and KYN pathways may underlie the emotional dysfunctions observed in individuals exposed to stress during in utero development.

Learning Deficits Induced by High-Calorie Feeding in the Rat are Associated With Impaired Brain Kynurenine Pathway Metabolism.

In addition to be a primary risk factor for type 2 diabetes and cardiovascular disease, obesity is associated with learning disabilities. Here we examined whether a dysregulation of the kynurenine pathway (KP) of tryptophan (Trp) metabolism might underlie the learning deficits exhibited by obese individuals. The KP is initiated by the enzymatic conversion of Trp into kynurenine (KYN) by indoleamine 2,3-dioxygenase (IDO). KYN is further converted to several signaling molecules including quinolinic acid (QA) which has a negative impact on learning. Wistar rats were fed either standard chow or made obese by exposure to a free choice high-fat high-sugar (fcHFHS) diet. Their learning capacities were evaluated using a combination of the novel object recognition and the novel object location tasks, and the concentrations of Trp and KYN-derived metabolites in several brain regions determined by ultra-performance liquid chromatography-tandem mass spectrometry. Male, but not female, obese rats exhibited reduced learning capacity characterized by impaired encoding along with increased hippocampal concentrations of QA, Xanthurenic acid (XA), Nicotinamide (Nam), and oxidized Nicotinamide Adenine Dinucleotide (NAD+). In contrast, no differences were detected in the serum levels of Trp or KP metabolites. Moreover, obesity enhanced the expression in the hippocampus and frontal cortex of kynurenine monooxygenase (KMO), an enzyme involved in the production of QA from kynurenine. QA stimulates the glutamatergic system and its increased production leads to cognitive impairment. These results suggest that the deleterious effects of obesity on cognition are sex dependent and that altered KP metabolism might contribute to obesity-associated learning disabilities.

Untargeted lipidomic analysis of plasma from obese women submitted to combined physical exercise.

This study aimed to determine the changes of lipidome in obese women undergoing combined physical exercise training. Fourteen adult women with obesity (mean BMI and age, 33 kg/m2 and 34 ± 5 years), were submitted to combined physical training (aerobic and strength exercises, alternately, 55 min at 75-90% of the maximum heart rate, 3 times a week) for 8 weeks. All participants were evaluated before and after the training intervention for lipidome, anthropometric measurements, muscle strength, and maximum oxygen consumption (VO2max). Untargeted liquid chromatography-mass spectrometry analyses allowed the identification of 1252 variables, of which 160 were significant (p < 0.05), and 61 were identified as molecular species of lipids. Volcano plot analysis revealed LPC(16:0p), LPC(18:0p), LPC(20:2), and arachidonic acid upregulated and PC(38:1p), PC(40:4), PC(40:4p) downregulated after combined physical exercise. From the results of the overall Principal component analysis (PCA), the major finding was SM(d18:1/20:0), arachidonic acid, and PC(40:6) species. Other changes included a reduction in waist circumference (Δ = - 2 cm) (p < 0.05), with no weight loss. In conclusion, 8-week of combined exercise training in obese women brought changes in different classes of lipids. This study provides further information to understand the effect of combined physical exercise on lipids related to obesity.

Bariatric Surgery Improves the Atherogenic Profile of Circulating Methylarginines in Obese Patients: Results from a Pilot Study.

Bariatric surgery improves obesity-related comorbidities. Methylarginines are biomarkers of cardiometabolic risk, liver steatosis, and insulin resistance. Here, we aimed to investigate methylarginines in obese patients undergoing bariatric surgery and compared them to age- and sex-matched healthy subjects. Thirty-one obese patients who underwent bariatric surgery and 31 healthy individuals were used for this retrospective study. The basal serum methylarginine levels were determined in the healthy individuals and the obese patients, before surgery and 6 and 12 months after surgery, by mass spectrometry. Compared with the healthy individuals, the obese patients displayed elevated monomethylarginine (mean change: +95%, p < 0.001), asymmetric-dimethylarginine (+105%, p < 0.001), symmetric-dimethylarginine (+25%, p = 0.003), and dimethylguanidino valerate (+32%, p = 0.008) concentrations. Bariatric surgery durably reduced the body mass index by 28% (12 months, 95%CI: 24-33, p = 0.002) and improved plasma lipids, insulin resistance, and liver function. Bariatric surgery reduced the serum levels of monomethylarginine and asymmetric-dimethylarginine by 12% (95%CI: 6-17) and 36% (95%CI: 27-45) (12 months, p = 0.003), respectively, but not symmetric-dimethylarginine or dimethylguanidino valerate. The monomethylarginine and asymmetric-dimethylarginine concentrations were strongly correlated with markers of dyslipidemia, insulin resistance, and a fatty liver. Serum dimethylguanidino valerate was primarily correlated with glycemia and renal function, whereas serum symmetric-dimethylarginine was almost exclusively associated with renal function. In conclusion, the monomethylarginine and asymmetric-dimethylarginine levels are efficiently decreased by bariatric surgery, leading to a reduced atherogenic profile in obese patients. Methylarginines follow different metabolic patterns, which could help for the stratification of cardiometabolic disorders in obese patients.

Perinatal Administration of C-Phycocyanin Protects Against Atherosclerosis in apoE-Deficient Mice by Modulating Cholesterol and Trimethylamine-N-Oxide Metabolisms.

OBJECTIVE: Gestational hypercholesterolemia concomitantly with a highly oxidative environment is associated with higher atherosclerosis in human and animal offspring. This work aimed to determine whether perinatal administration of a C-phycocyanin concentrate, a powerful antioxidant, can protect against atherosclerosis development in genetically hypercholesterolemic mice in adult life. Approach and Results: C-Phycocyanin was administered during gestation solely or gestation and lactation to apolipoprotein E-deficient mice. Male and female offspring were studied until 25 weeks old. Progenies born to supplemented mothers displayed significantly less atherosclerotic root lesions than control group in all groups excepted in male supplemented during gestation and lactation. Female born to supplemented mothers had a greater gallbladder total bile acid pool, lower secondary hydrophobic bile acid levels such as lithocholic acid, associated with less plasma trimethylamine N-oxide at 16 weeks old compared with control mice. Regarding male born to C-Phycocyanin administrated mothers, they expressed a higher high-density lipoprotein cholesterol level, more soluble bile acids such as ß-muricholic acids, and a decreased plasma trimethylamine at 16 weeks old. Liver reduced-to-oxidized glutathione ratio were increased and liver gene expression of superoxide dismutase and glutathione peroxidase were significantly decreased in male born to gestational supplemented mothers. No difference in the composition of cecal microbiota was found between groups, regardless of sex. CONCLUSIONS: Our findings suggest a protective effect of perinatal antioxidant administration on atherosclerosis development in apolipoprotein E-deficient mice involving sex-specific mechanisms.

Dietary Arginine Supplementation during Gestation and Lactation Increases Milk Yield and Mammary Lipogenesis in Rats.

BACKGROUND: Arginine, an essential amino acid during the reproductive period, has been shown to enhance lactation performances in livestock. Whether it could help mothers with breastfeeding difficulties is not known. OBJECTIVES: This study aimed to determine whether dietary arginine supplementation would enhance milk production in rat dams nursing large 12-pup litters and, if so, what mechanisms are involved. METHODS: In 3 series of experiments, differing in dam killing timing, 59 primiparous, pregnant Sprague-Dawley rats (mean ± SD weight: 254 ± 24.7 g) were randomly assigned to receive either 1) an AIN-93G diet supplemented with l-arginine at 2.0% (ARG diet), through lactation and gestation (AGL group); 2) a control AIN-93G diet including at 3.5% an isonitrogenous mix of amino acids that are not essential for lactation (MA diet), during gestation and lactation (MA group); or 3) the MA diet during gestation and the ARG diet during lactation (AL group). Milk flow was measured using deuterated water enrichment between days 11 and 18. Plasma hormones and mammary expression of genes involved in lactation were measured using ELISA and qRT-PCR, respectively, at lactation days 12, 18, or 21 in the 3 experiments. Data were analyzed by ANOVA. RESULTS: Dam food intake, pup weight gain, milk flow normalized to dam weight, and milk fat concentration were 17%, 9%, 20%, and 20% greater in the AGL group than in the MA group, respectively (P < 0.05). Genes involved in lipogenesis and lipid regulation were overexpressed ≤2.76-fold in the mammary gland of AGL dams compared with MA dams (P < 0.05) and plasma leptin concentration was 39% higher (P = 0.008). Milk flow and composition and mammary gene expression of the AL group did not differ from those of the MA group, whereas milk fat concentration and flow were 26% and 37% lower than in the AGL group, respectively. CONCLUSIONS: Arginine supplementation during gestation and lactation enhances milk flow and mammary lipogenesis in rats nursing large litters.

Spirulina liquid extract prevents metabolic disturbances and improves liver sphingolipids profile in hamster fed a high-fat diet.

PURPOSE: Metabolic syndrome is characterized by hyperglycemia, hyperlipemia and exacerbated oxidative stress. The aim of the study was to determine whether Spirulysat®, a Spirulina liquid extract (SLE) enriched in phycocyanin, would prevent metabolic abnormalities induced by high-fat diet. METHODS: The effect of acute SLE supplementation on postprandial lipemia and on triton-induced hyperlipidemia was studied in hamster fed control diet (C). The effect of chronic SLE supplementation on lipid content in plasma, liver and aorta, and on glycemia and oxidative stress was studied in hamster fed control (C) or high-fat diet (HF) for two weeks and then treated with SLE for two weeks (CSp and HFSp) or not (C and HF). RESULTS: The acute SLE supplementation lowered plasma cholesterol and non-esterified fatty acid concentrations after olive oil gavage (P < 0.05) in CSp, while no effect was observed on triglyceridemia. HFD increased plasma MDA, basal glycemia, triglyceridemia, total plasma cholesterol, VLDL, LDL and HDL cholesterol, ceramide, sphingomyelin and glucosylceramide content in liver in HF compared to C (P < 0.05). SLE did not affect SOD and GPx activities nor total antioxidant status in HFSp group but lowered glycemia, glucoceramide and cholesterol in liver and cholesterol in aorta compared to HF (P < 0.05). SLE also decreased HMGCoA and TGF-ß1 gene expression in liver (P < 0.05) and tended to lower G6Pase (P = 0.068) gene expression in HFSp compared to HF. CONCLUSION: Although 2-week SLE supplementation did not affect oxidative stress, it protected from hyperglycemia and lipid accumulation in liver and aorta suggesting a protective effect against metabolic syndrome.

Effects of proprotein convertase subtilisin kexin type 9 modulation in human pancreatic beta cells function.

BACKGROUND AND AIMS: Proprotein Convertase Subtilisin Kexin Type 9 (PCSK9) is an endogenous inhibitor of the LDL receptor (LDLR). Mendelian randomization studies suggest that PCSK9 deficiency increases diabetes risk, but the underlying mechanisms remain unknown. The aim of our study was to investigate whether PCSK9 or its inhibition may modulate beta cell function. METHODS: We assessed PCSK9 and insulin colocalization in human pancreatic sections by epifluorescent and confocal microscopy. We also investigated the expression and the function of PCSK9 in the human EndoC-ßH1 beta cell line, by ELISA and flow cytometry, respectively. PCSK9 was inhibited with Alirocumab or siRNA. LDLR expression and LDL uptake were assessed by flow cytometry. RESULTS: PCSK9 was expressed and secreted from beta cells isolated from human pancreas as well as from EndoC-ßH1 cells. PCSK9 secretion was enhanced by statin treatment. Recombinant PCSK9 decreased LDLR abundance at the surface of these cells, an effect abrogated by Alirocumab. Alirocumab as well as PCSK9 silencing increased LDLR expression at the surface of EndoC-ßH1 cells. Neither exogenous PCSK9, nor Alirocumab, nor PCSK9 silencing significantly altered glucose-stimulated insulin secretion (GSIS) from these cells. High-low density lipoproteins (LDL) concentrations decreased GSIS, but the addition of PCSK9 or its inhibition did not modulate this phenomenon. CONCLUSIONS: While PCSK9 regulates LDLR abundance in beta cells, inhibition of exogenous or endogenous PCSK9 does not appear to significantly impact insulin secretion. This is reassuring for the safety of PCSK9 inhibitors in terms of beta cell function.

Omega 3 Improves Both apoB100-containing Lipoprotein Turnover and their Sphingolipid Profile in Hypertriglyceridemia.

CONTEXT: Evidence for an association between sphingolipids and metabolic disorders is increasingly reported. Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) improve apolipoprotein B100 (apoB100)-containing lipoprotein metabolism, but their effects on the sphingolipid content in lipoproteins remain unknown. OBJECTIVES: In subjects with hypertriglyceridemia, we analyzed the effect of n-3 LC-PUFAs on the turnover apoB100-containing lipoproteins and on their sphingolipid content and looked for the possible association between these lipid levels and apoB100-containing lipoprotein turnover parameters. METHODS: Six subjects underwent a kinetic study before and after n-3 supplementation for 2 months with 1 g of fish oil 3 times day containing 360 mg of eicosapentaenoic acid (EPA) and 240 mg of docosahexaenoic acid (DHA) in the form of triglycerides. We examined apoB100-containing lipoprotein turnover by primed perfusion labeled [5,5,5-2H3]-leucine and determined kinetic parameters using a multicompartmental model. We quantified sphingolipid species content in lipoproteins using mass spectrometry. RESULTS: Supplementation decreased very low-density lipoprotein (VLDL), triglyceride, and apoB100 concentrations. The VLDL neutral and polar lipids showed increased n-3 LC-PUFA and decreased n-6 LC-PUFA content. The conversion rate of VLDL1 to VLDL2 and of VLDL2 to LDL was increased. We measured a decrease in total apoB100 production and VLDL1 production. Supplementation reduced the total ceramide concentration in VLDL while the sphingomyelin content in LDL was increased. We found positive correlations between plasma palmitic acid and VLDL ceramide and between VLDL triglyceride and VLDL ceramide, and inverse correlations between VLDL n-3 LC-PUFA and VLDL production. CONCLUSION: Based on these results, we hypothesize that the improvement in apoB100 metabolism during n-3 LC-PUFA supplementation is contributed to by changes in sphingolipids.

A high-throughput mass spectrometry-based assay for large-scale profiling of circulating human apolipoproteins.

Apolipoproteins govern lipoprotein metabolism and are promising biomarkers of metabolic and cardiovascular diseases. Unlike immunoassays, MS enables the quantification and phenotyping of multiple apolipoproteins. Hence, here, we aimed to develop a LC-MS/MS assay that can simultaneously quantitate 18 human apolipoproteins [A-I, A-II, A-IV, A-V, B48, B100, C-I, C-II, C-III, C-IV, D, E, F, H, J, L1, M, and (a)] and determined apoE, apoL1, and apo(a) phenotypes in human plasma and serum samples. The plasma and serum apolipoproteins were trypsin digested through an optimized procedure and peptides were extracted and analyzed by LC-MS/MS. The method was validated according to standard guidelines in samples spiked with known peptide amounts. The LC-MS/MS results were compared with those obtained with other techniques, and reproducibility, dilution effects, and stabilities were also assessed. Peptide markers were successfully selected for targeted apolipoprotein quantification and phenotyping. After optimization, the assay was validated for linearity, lower limits of quantification, accuracy (biases: -14.8% to 12.1%), intra-assay variability [coefficients of variation (CVs): 1.5-14.2%], and inter-assay repeatability (CVs: 4.1-14.3%). Bland-Altman plots indicated no major statistically significant differences between LC-MS/MS and other techniques. The LC-MS/MS results were reproducible over five repeated experiments (CVs: 1.8-13.7%), and we identified marked differences among the plasma and serum samples. The LC-MS/MS assay developed here is rapid, requires only small sampling volumes, and incurs reasonable costs, thus making it amenable for a wide range of studies of apolipoprotein metabolism. We also highlight how this assay can be implemented in laboratories.

Secretion of Acid Sphingomyelinase and Ceramide by Endothelial Cells Contributes to Radiation-Induced Intestinal Toxicity.

Ceramide-induced endothelial cell apoptosis boosts intestinal stem cell radiosensitivity. However, the molecular connection between these two cellular compartments has not been clearly elucidated. Here we report that ceramide and its related enzyme acid sphingomyelinase (ASM) are secreted by irradiated endothelial cells and act as bystander factors to enhance the radiotoxicity of intestinal epithelium. Ceramide and the two isoforms of ASM were acutely secreted in the blood serum of wild-type mice after 15 Gy radiation dose, inducing a gastrointestinal syndrome. Interestingly, serum ceramide was not enhanced in irradiated ASMKO mice, which are unable to develop intestinal failure injury. Because ASM/ceramide were secreted by primary endothelial cells, their contribution was studied in intestinal epithelium dysfunction using coculture of primary endothelial cells and intestinal T84 cells. Adding exogenous ASM or ceramide enhanced epithelial cell growth arrest and death. Conversely, blocking their secretion by endothelial cells using genetic, pharmacologic, or immunologic approaches abolished intestinal T84 cell radiosensitivity. Use of enteroid models revealed ASM and ceramide-mediated deleterious mode-of-action: when ceramide reduced the number of intestinal crypt-forming enteroids without affecting their structure, ASM induced a significant decrease of enteroid growth without affecting their number. Identification of specific and different roles for ceramide and ASM secreted by irradiated endothelial cells opens new perspectives in the understanding of intestinal epithelial dysfunction after radiation and defines a new class of potential therapeutic radiomitigators. SIGNIFICANCE: This study identifies secreted ASM and ceramide as paracrine factors enhancing intestinal epithelial dysfunction, revealing a previously unknown class of mediators of radiosensitivity.

Plasma Trimethylamine N-Oxide and Risk of Cardiovascular Events in Patients With Type 2 Diabetes.

OBJECTIVE: Even though trimethylamine N-oxide (TMAO) has been demonstrated to interfere with atherosclerosis and diabetes pathophysiology, the association between TMAO and major adverse cardiovascular events (MACE) has not been specifically established in type 2 diabetes (T2D). RESEARCH DESIGN AND METHODS: We examined the association of plasma TMAO concentrations with MACE and all-cause mortality in a single-center prospective cohort of consecutively recruited patients with T2D. RESULTS: The study population consisted in 1463 SURDIENE participants (58% men), aged 65 ±â€…10 years. TMAO concentrations were significantly associated with diabetes duration, renal function, high-density lipoprotein cholesterol, soluble tumor necrosis factor receptor 1 (sTNFR1) concentrations (R2 = 0.27) and were significantly higher in patients on metformin, even after adjustment for estimated glomerular filtration rate (eGFR): 6.7 (8.5) vs 8.5 (13.6) µmol/L, respectively (PeGFR-adjusted = 0.0207). During follow-up (median duration [interquartile range], 85 [75] months), 403 MACE and 538 deaths were registered. MACE-free survival and all-cause mortality were significantly associated with the quartile distribution of TMAO concentrations, patients with the highest TMAO levels displaying the greatest risk of outcomes (P < 0.0001). In multivariate Cox models, compared with patients from the first 3 quartiles, those from the fourth quartile of TMAO concentration had an independently increased risk for MACE: adjusted hazard ratio (adjHR) 1.32 (1.02-1.70); P = 0.0325. Similarly, TMAO was significantly associated with mortality in multivariate analysis: adjHR 1.75 (1.17-2.09); P = 0.0124, but not when sTNFR1 and angiopoietin like 2 were considered: adjHR 1.16 (0.95-1.42); P = 0.1514. CONCLUSIONS: We revealed an association between higher TMAO concentrations and increased risk of MACE and all-cause mortality, thereby opening some avenues on the role of dysbiosis in cardiovascular risk, in T2D patients.

VLDL (Very-Low-Density Lipoprotein)-Apo E (Apolipoprotein E) May Influence Lp(a) (Lipoprotein [a]) Synthesis or Assembly.

OBJECTIVE: To clarify the association between PCSK9 (proprotein convertase subtilisin/kexin type 9) and Lp(a) (lipoprotein [a]), we studied Lp(a) kinetics in patients with loss-of-function and gain-of-function PCSK9 mutations and in patients in whom extended-release niacin reduced Lp(a) and PCSK9 concentrations. Approach and Results: Six healthy controls, 9 heterozygous patients with familial hypercholesterolemia (5 with low-density lipoprotein receptor [LDLR] mutations and 4 with PCSK9 gain-of-function mutations) and 3 patients with heterozygous dominant-negative PCSK9 loss-of-function mutations were included in the preliminary study. Eight patients were enrolled in a second study assessing the effects of 2 g/day extended-release niacin. Apolipoprotein kinetics in VLDL (very-low-density lipoprotein), LDL (low-density lipoprotein), and Lp(a) were studied using stable isotope techniques. Plasma Lp(a) concentrations were increased in PCSK9-gain-of-function and familial hypercholesterolemia-LDLR groups compared with controls and PCSK9-loss-of-function groups (14±12 versus 5±4 mg/dL; P=0.04), but no change was observed in Lp(a) fractional catabolic rate. Subjects with PCSK9-loss-of-function mutations displayed reduced apoE (apolipoprotein E) concentrations associated with a VLDL-apoE absolute production rate reduction. Lp(a) and VLDL-apoE absolute production rates were correlated (r=0.50; P<0.05). ApoE-to-apolipoprotein (a) molar ratios in Lp(a) increased with plasma Lp(a) (r=0.96; P<0.001) but not with PCSK9 levels. Extended-release niacin-induced reductions in Lp(a) and VLDL-apoE absolute production rate were correlated (r=0.83; P=0.015). In contrast, PCSK9 reduction (-35%; P=0.008) was only correlated with that of VLDL-apoE absolute production rate (r=0.79; P=0.028). CONCLUSIONS: VLDL-apoE production could determine Lp(a) production and/or assembly. As PCSK9 inhibitors reduce plasma apoE and Lp(a) concentrations, apoE could be the link between PCSK9 and Lp(a).

Human Tolerogenic Dendritic Cells Regulate Immune Responses through Lactate Synthesis.

Cell therapy is a promising strategy for treating patients suffering from autoimmune or inflammatory diseases or receiving a transplant. Based on our preclinical studies, we have generated human autologous tolerogenic dendritic cells (ATDCs), which are being tested in a first-in-man clinical trial in kidney transplant recipients. Here, we report that ATDCs represent a unique subset of monocyte-derived cells based on phenotypic, transcriptomic, and metabolic analyses. ATDCs are characterized by their suppression of T cell proliferation and their expansion of Tregs through secreted factors. ATDCs produce high levels of lactate that shape T cell responses toward tolerance. Indeed, T cells take up ATDC-secreted lactate, leading to a decrease of their glycolysis. In vivo, ATDCs promote elevated levels of circulating lactate and delay graft-versus-host disease by reducing T cell proliferative capacity. The suppression of T cell immunity through lactate production by ATDCs is a novel mechanism that distinguishes ATDCs from other cell-based immunotherapies.

Elevation of Trimethylamine-N-Oxide in Chronic Kidney Disease: Contribution of Decreased Glomerular Filtration Rate.

Gut microbiota-dependent Trimethylamine-N-oxide (TMAO) has been reported to be strongly linked to renal function and to increased cardiovascular events in the general population and in Chronic Kidney Disease (CKD) patients. Considering the lack of data assessing renal handling of TMAO, we conducted this study to explore renal excretion and mechanisms of accumulation of TMAO during CKD. We prospectively measured glomerular filtration rate (mGFR) with gold standard methods and plasma concentrations of trimethylamine (TMA), TMAO, choline, betaine, and carnitine by LC-MS/MS in 124 controls, CKD, and hemodialysis (HD) patients. Renal clearance of each metabolite was assessed in a sub-group of 32 patients. Plasma TMAO was inversely correlated with mGFR (r2 = 0.388, p < 0.001), confirming elevation of TMAO plasma levels in CKD. TMAO clearances were not significantly different from mGFR, with a mean ± SD TMAO fractional excretion of 105% ± 32%. This suggests a complete renal excretion of TMAO by glomerular filtration with a negligible participation of tubular secretion or reabsorption, during all stages of CKD. Moreover, TMAO was effectively removed within 4 h of hemodiafiltration, showing a higher fractional reduction value than that of urea (84.9% ± 6.5% vs. 79.2% ± 5.7%, p = 0.04). This study reports a strong correlation between plasma TMAO levels and mGFR, in CKD, that can be mainly related to a decrease in TMAO glomerular filtration. Clearance data did not support a significant role for tubular secretion in TMAO renal elimination.

Impact of Fenugreek on Milk Production in Rodent Models of Lactation Challenge.

Fenugreek, a herbal remedy, has long been used as galactologue to help mothers likely to stop breastfeeding because of perceived insufficient milk production. However, few studies highlight the efficacy of fenugreek in enhancing milk production. The aims of our study were to determine whether fenugreek increased milk yield in rodent models of lactation challenge and if so, to verify the lack of adverse effects on dam and offspring metabolism. Two lactation challenges were tested: increased litter size to 12 pups in dams fed a 20% protein diet and perinatal restriction to an 8% protein diet with eight pups' litter, with or without 1 g.kg-1.day-1 dietary supplementation of fenugreek, compared to control dams fed 20% protein diet with eight pups' litters. Milk flow was measured by the deuterium oxide enrichment method, and milk composition was assessed. Lipid and glucose metabolism parameters were assessed in dam and offspring plasmas. Fenugreek increased milk production by 16% in the litter size increase challenge, resulting in an 11% increase in pup growth without deleterious effect on dam-litter metabolism. Fenugreek had no effect in the maternal protein restriction challenge. These results suggest a galactologue effect of fenugreek when mothers have no physiological difficulties in producing milk.

Spirulina Liquid Extract Protects against Fibrosis Related to Non-Alcoholic Steatohepatitis and Increases Ursodeoxycholic Acid.

Non-alcoholic steatohepatitis (NASH) is characterized by an excess of lipids and oxidative stress in the liver. Spirulina was reported to possess hypolipemic and antioxidative effects and might counteract NASH development. C57Bl/6J mice were fed a western diet (WD) during 25 weeks with or without spirulina liquid extract (SLE) at 2 different doses (WDS1 and WDS2 groups) in drinking water. Liver histology, inflammation, and oxidative stress were assessed as well as glucose tolerance status, lipid metabolism, and gallbladder bile acid profile. WDS2 gained significantly less weight than WD. Liver weight-to-body weight ratio and plasma alanine aminotransferase were significantly lower in WDS2 mice. A reduced liver fibrosis and NFκBp65 protein expression were measured in the supplemented group as a lower accumulation of superoxide anion, nitric oxide, and thiobarbituric reactive substances. WDS2 mice showed also a preserved glucose tolerance, a strong decrease of plasma cholesterol, and a significant increase of gallbladder ursodeoxycholic acid and ß-muricholic acid. Our findings demonstrate a protective effect of SLE against WD induced NASH that is related to less inflammation and oxidative stress, a preserved glucose tolerance, and less hepatotoxic bile acid profile.

In vivo evidence for transintestinal cholesterol efflux in patients with complete common bile duct obstruction.

BACKGROUND: Beyond the hepatobiliary pathway, studies have demonstrated that direct transintestinal cholesterol efflux (TICE) of plasma-derived cholesterol may contribute to reverse cholesterol transport. The clinical evidence of TICE in human remains challenged because of the difficulty to discriminate the hepatobiliary and transintestinal routes in vivo. OBJECTIVE: To provide the first proof of concept that TICE exists in vivo in humans by demonstrating that plasma labeled cholesterol can be excreted in the feces of patients with complete bile duct obstruction. METHODS: Plasma, bile, and fecal cholesterol excretion was measured by mass spectrometry 24, 48, and 72 hours after intravenous injection of D7-cholesterol in two patients presenting cholangiocarcinomas with a total obstruction of their primary bile duct. RESULTS: No trace of bile acids was detected in the feces of the two patients. Despite this, a significant amount of plasma D7-cholesterol was quantified in the feces of the two patients 48 hours and 72 hours after the intravenous injection. CONCLUSION: Our data bring a direct proof that TICE is an active pathway in humans.

Plasma lipidomic analysis reveals strong similarities between lipid fingerprints in human, hamster and mouse compared to other animal species.

Cardiovascular diseases are often associated with impaired lipid metabolism. Animal models are useful for deciphering the physiological mechanisms underlying these pathologies. However, lipid metabolism is contrasted between species limiting the transposition of findings from animals to human. Hence, we aimed to compare extended lipid profiles of several animal species to bring new insights in animal model selections. Human lipid phenotype was compared with those of 10 animal species. Standard plasma lipids and lipoprotein profiles were obtained by usual methods and lipidomic analysis was conducted by liquid chromatography-high-resolution mass spectrometry (LC-HRMS). As anticipated, we found contrasted lipid profiles between species. Some of them exhibited similar plasma lipids to human (non-human primate, rat, hamster, pig), but only usual lipid profiles of pigs were superimposable with human. LC-HRMS analyses allowed the identification of 106 other molecular species of lipids, common to all samples and belonging to major lipid families. Multivariate analyses clearly showed that hamster and, in a lower extent mouse, exhibited close lipid fingerprints to that of human. Besides, several lipid candidates that were previously reported to study cardiovascular diseases ranged similarly in human and hamster. Hence, hamster appeared to be the best option to study physiological disturbances related to cardiovascular diseases.