N-acetylcysteine, xCT and suppression of Maxi-chloride channel activity in human placenta.

INTRODUCTION: Placental oxidative stress features in pregnancy pathologies but in clinical trials antioxidant supplementation has not improved outcomes. N-acetylcysteine (NAC) stimulates glutathione production and is proposed as a therapeutic agent in pregnancy. However, key elements of N-acetylcysteine biology, including its cellular uptake mechanism, remains unclear. This study explores how the cystine/glutamate transporter xCT may mediate N-acetylcysteine uptake and how N-acetylcysteine alters placental redox status. METHODS: The involvement of xCT in NAC uptake by the human placenta was studied in perfused placenta and Xenopus oocytes. The effect of short-term N-acetylcysteine exposure on the placental villous proteome was determined using LC-MS. The effect of N-acetylcysteine on Maxi-chloride channel activity was investigated in perfused placenta, villous fragments and cell culture. RESULTS: Maternoplacental N-acetylcysteine administration stimulated intracellular glutamate efflux suggesting a role of the exchange transporter xCT, which was localised to the microvillous membrane of the placental syncytiotrophoblast. Placental exposure to a bolus of N-acetylcysteine inhibited subsequent activation of the redox sensitive Maxi-chloride channel independently of glutathione synthesis. Stable isotope quantitative proteomics of placental villi treated with N-acetylcysteine demonstrated changes in pathways associated with oxidative stress, apoptosis and the acute phase response. DISCUSSION: This study suggests that xCT mediates N-acetylcysteine uptake into the placenta and that N-acetylcysteine treatment of placental tissue alters the placental proteome while regulating the redox sensitive Maxi-chloride channel. Interestingly N-acetylcysteine had antioxidant effects independent of the glutathione pathway. Effective placental antioxidant therapy in pregnancy may require maintaining the balance between normalising redox status without inhibiting physiological redox signalling.

Marine omega-3 fatty acid supplementation in non-alcoholic fatty liver disease: Plasma proteomics in the randomized WELCOME* trial.

BACKGROUND & AIMS: Non-alcoholic fatty liver disease (NAFLD) is a liver condition characterised by liver fat accumulation and often considered to be the liver manifestation of metabolic syndrome. The aim of this study was to examine in patients with NAFLD the system-wide effects of treatment with docosahexaenoic acid + eicosapentaenoic acid (DHA + EPA) versus placebo on the plasma proteome. METHODS: Plasma from patients that participated in a 15-18 months randomised, double-blind placebo-controlled trial testing the effects of 4 g DHA + EPA daily was analysed using depletion-free quantitative proteomics. RESULTS: Bioinformatics interpretation of the proteomic analysis showed that DHA + EPA treatment affected pathways involving blood coagulation, immune/inflammatory response and cholesterol metabolism (p < 0.05). Two key proteins of cardiovascular risk, prothrombin and apolipoprotein B-100, were shown to decrease as a result of DHA + EPA supplementation [Prothrombin: Males DHA + EPA Mean iTRAQ log2ratio (SD) = -0.13 (0.20) p = 0.05, Females DHA + EPA Mean iTRAQ log2ratio (SD) = -0.48 (0.35) p = 0.03; Apo B-100: Males DHA + EPA Mean iTRAQ log2ratio (SD) = -0.24 (0.16) p = 0.01, Females DHA + EPA Mean iTRAQ log2ratio (SD) = -0.15 (0.05) p = 0.02]. CONCLUSIONS: Plasma proteomics applied in a randomised, placebo-controlled trial showed that high dose DHA + EPA treatment in patients with NAFLD affects multiple pathways involved in chronic non-communicable diseases.

Identification of a novel interaction between corticotropin releasing hormone (Crh) and macroautophagy.

In inflammatory bowel disease (IBD), compromised restitution of the epithelial barrier contributes to disease severity. Owing to the complexity in the pathogenesis of IBD, a variety of factors have been implicated in its progress. In this study, we report a functional interaction between macroautophagy and Corticotropin Releasing Hormone (Crh) in the gut. For this purpose we used DSS colitis model on Crh -/- or wild-type (wt) with pharmacological inhibition of autophagy. We uncovered sustained basal autophagy in the gut of Crh -/- mice, which persisted over the course of DSS administration. Autophagy inhibition resulted in partial rescue of Crh -/- mice, while it increased the expression of Crh in the wt gut. Similarly, Crh deficiency was associated with sustained activation of base line autophagy. In vitro models of amino acid deprivation- and LPS-induced autophagy confirmed the in vivo findings. Our results indicate a novel role for Crh in the intestinal epithelium that involves regulation of autophagy, while suggesting the complementary action of the two pathways. These data suggest the intriguing possibility that targeting Crh stimulation in the intestine may provide a novel therapeutic approach to support the integrity of the epithelial barrier and to protect from chronic colitis.

Vitamin D and cardiovascular risk among adults with obesity: a systematic review and meta-analysis.

BACKGROUND: Obesity is a risk factor for both vitamin D deficiency and cardiovascular disease. A link between vitamin D status optimisation and improved cardiometabolic profile among adults with obesity could inform public health initiatives. METHODS: PubMed, Embase and Web of Science were searched for interventional studies examining the effects of vitamin D status improvement on cardiovascular risk factors (anthropometric measures, lipid profile, blood pressure, glucose tolerance) among nondiabetic adults with obesity. RESULTS: Seventeen publications reporting results from 11 different studies were included. Number of participants ranged from 34 to 1179 subjects. Duration was between 6 weeks and 4 years. Vitamin D was administered as a supplement in ten studies (1000 IU daily to 120 000 IU fortnightly). In one study, participants were advised to increase sunlight exposure and dietary vitamin D intake. The random and fixed-effects meta-analysis showed that vitamin D significantly increased systolic blood pressure and LDL-C levels. The fixed-effects model also indicated a significant decrease in triglyceride levels, which was not evident using the random-effects model. Caution should be given to these results given the small number of studies used and the high heterogeneity between studies for the two latter outcomes. Additionally, a subset of eligible studies with compatible data presentation was included in the meta-analysis. CONCLUSION: This systematic review highlights a paucity of interventional studies examining the effects of vitamin D status improvement on cardiovascular risk factors among otherwise healthy adults with obesity. Large-scale studies at pharmacologically relevant doses and with sufficient duration are warranted.

Analysis of the in vitro metabolites of diferuloylmethane (curcumin) by liquid chromatography--tandem mass spectrometry on a hybrid quadrupole linear ion trap system: newly identified metabolites.

In this study, we have described a novel approach for determining the metabolic scheme of diferuloylmethane (curcumin) in mouse and human liver microsomal preparations using a hybrid quadrupole linear ion trap mass spectrometer coupled with liquid chromatography for the detection of new metabolites. Application of various acquisition modes allowed targeted searches for metabolites with high sensitivity and selectivity using information of the mass spectral fragmentation properties of curcumin. Structural assignments for metabolites previously reported in the literature were made with confidence using the described approach. In addition, we identified curcumin metabolites that had not previously been reported, such as curcumin bisglucuronide and O-demethylated derivatives. The major pathways of curcumin metabolism in vitro have been summarized. Finally, very similar metabolic pathways of curcumin were observed in human and mouse microsomes.

A dual-isotope-labeling method of studying the bioavailability of hexaglutamyl folic acid relative to that of monoglutamyl folic acid in humans by using multiple orally administered low doses.

BACKGROUND: The bioavailability of dietary folate may be hampered by the need of the glutamate moieties to be deconjugated before absorption. Previous studies comparing the bioavailabilities of polyglutamyl and monoglutamyl folic acid had inconsistent results. OBJECTIVE: The objective was to estimate the bioavailability of polyglutamyl relative to that of monoglutamyl folic acid by using a sensitive stable-isotope approach that allowed for the administration of multiple low doses in humans. DESIGN: Twenty subjects aged 20-50 y ingested 2 capsules daily for 28 d; each capsule contained approximately 50 nmol [(13)C(6)]hexaglutamyl and approximately 50 nmol [(13)C(11)]monoglutamyl folic acid. Amounts of the isotopically labeled compounds in the capsules were verified by various methods. The degrees of isotopic enrichment of plasma 5-methyltetrahydrofolate with (13)C(6) and (13)C(11) were measured by using liquid chromatography tandem mass spectrometry, and the ratio of (13)C(6) to (13)C(11) ((13)C(6):(13)C(11)) in plasma on day 28 was used as a measure of their relative bioavailability. RESULTS: The (13)C(11):(13)C(6) in plasma 5-methyltetrahydrofolate reached equilibrium on day 4 and was 0.66 (95% CI: 0.58, 0.74) on day 28. The (13)C(11):(13)C(6) content in the capsules varied between 1.18 and 1.96. After correction for this ratio, the estimated bioavailability of hexaglutamyl relative to that of monoglutamyl folic acid was >/=78%. CONCLUSION: Multiple dosing of low amounts of labeled folic acid is a sensitive, accurate, and efficient method of measuring the relative bioavailability of folic acid compounds, provided that the administered doses can be reliably assessed.