Increased plasma homocysteine and S-adenosylhomocysteine and decreased methionine is associated with altered phosphatidylcholine and phosphatidylethanolamine in cystic fibrosis

Low-dose vanadium pentoxide perturbed lung metabolism associated with inflammation and fibrosis signaling in male animal and in vitro models

Vanadium is available as a dietary supplement and also is known to be toxic if inhaled, yet little information is available concerning the effects of vanadium on mammalian metabolism when concentrations found in food and water. Vanadium pentoxide (V+5) is representative of the most common dietary and environmental exposures, and prior research shows that low-dose V+5 exposure causes oxidative stress measured by glutathione oxidation and protein S-glutathionylation. We examined the metabolic impact of V+5 at relevant dietary and environmental doses (0.01, 0.1, and 1 ppm for 24 h) in human lung fibroblasts (HLFs) and male C57BL/6J mice (0.02, 0.2, and 2 ppm in drinking water for 7 mo). Untargeted metabolomics using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) showed that V+5 induced significant metabolic perturbations in both HLF cells and mouse lungs. We noted 30% of the significantly altered pathways in HLF cells, including pyrimidines and aminosugars, fatty acids, mitochondrial and redox pathways, showed similar dose-dependent patterns in mouse lung tissues. Alterations in lipid metabolism included leukotrienes and prostaglandins involved in inflammatory signaling, which have been associated with the pathogenesis of idiopathic pulmonary fibrosis (IPF) and other disease processes. Elevated hydroxyproline levels and excessive collagen deposition were also present in lungs from V+5-treated mice. Taken together, these results show that oxidative stress from environmental V+5, ingested at low levels, could alter metabolism to contribute to common human lung diseases.NEW & NOTEWORTHY We used relevant dietary and environmental doses of Vanadium pentoxide (V+5) to examine its metabolic impact in vitro and in vivo. Using liquid chromatography-high-resolution mass spectrometry (LC-HRMS), we found significant metabolic perturbations, with similar dose-dependent patterns observed in human lung fibroblasts and male mouse lungs. Alterations in lipid metabolism included inflammatory signaling, elevated hydroxyproline levels, and excessive collagen deposition were present in V+5-treated lungs. Our findings suggest that low levels of V+5 could trigger pulmonary fibrotic signaling.

Controlled attenuation parameter: A measure of hepatic steatosis in patients with cystic fibrosis

BACKGROUND

Hepatic steatosis is a common manifestation of CF-related liver disease(CFLD). Controlled attenuation parameter(CAP) measurement during transient elastography(TE) semiquantifies liver steatosis. We examined the relationship between CAP and CFLD severity, clinical factors and liver stiffness measurements(LSM).

METHODS

This is a cross-sectional study of CF patients seen for outpatient care between January 2013-March 2014. CFLD severity was categorized as no CFLD, CFLD without portal hypertension(PHTN) and CFLD with PHTN, based on published criteria.

RESULTS

129 patients (median 18.4y; 57% male) had valid CAP. 70(54%) had no CFLD, 44(34%) CFLD without PHTN, and 15(12%) CFLD with PHTN. The median CAP was 210 dB/m (IQR 181-239). Steatosis(CAP ≥230 dB/m) was seen in 27% of subjects without CFLD, 48% in CFLD but no PHTN, and 20% in with CFLD and PHTN(P = .04). CAP was higher for subjects with CFLD without PHTN (P < .05). There was no CAP difference between subjects with no CFLD and those with CFLD and PHTN (P ≥ .65). LSM was not different between no CFLD and CFLD without PHTN (P = .07), but each of these groups had lower LSM compared to subjects with CFLD and PHTN(P < .001 for each). Except for direct bilirubin, CAP was not associated with clinical markers of liver disease.

CONCLUSION

CAP was normal in 86(67%) of patients with CF and was not associated with standard clinical markers of liver disease. CAP was higher in patients with liver disease, which could possibly reflect the loss of steatosis observed with progression to cirrhosis and portal hypertension.

Homocysteine regulates fatty acid and lipid metabolism in yeast

S-Adenosyl-l-homocysteine hydrolase (AdoHcy hydrolase; Sah1 in yeast/AHCY in mammals) degrades AdoHcy, a by-product and strong product inhibitor of S-adenosyl-l-methionine (AdoMet)-dependent methylation reactions, to adenosine and homocysteine (Hcy). This reaction is reversible, so any elevation of Hcy levels, such as in hyperhomocysteinemia (HHcy), drives the formation of AdoHcy, with detrimental consequences for cellular methylation reactions. HHcy, a pathological condition linked to cardiovascular and neurological disorders, as well as fatty liver among others, is associated with a deregulation of lipid metabolism. Here, we developed a yeast model of HHcy to identify mechanisms that dysregulate lipid metabolism. Hcy supplementation to wildtype cells up-regulated cellular fatty acid and triacylglycerol content and induced a shift in fatty acid composition, similar to changes observed in mutants lacking Sah1. Expression of the irreversible bacterial pathway for AdoHcy degradation in yeast allowed us to dissect the impact of AdoHcy accumulation on lipid metabolism from the impact of elevated Hcy. Expression of this pathway fully suppressed the growth deficit of sah1 mutants as well as the deregulation of lipid metabolism in both the sah1 mutant and Hcy-exposed wildtype, showing that AdoHcy accumulation mediates the deregulation of lipid metabolism in response to elevated Hcy in yeast. Furthermore, Hcy supplementation in yeast led to increased resistance to cerulenin, an inhibitor of fatty acid synthase, as well as to a concomitant decline of condensing enzymes involved in very long-chain fatty acid synthesis, in line with the observed shift in fatty acid content and composition.

Glycerophospholipid Supplementation as a Potential Intervention for Supporting Cerebral Structure in Older Adults

Modifying nutritional intake through supplementation may be efficacious for altering the trajectory of cerebral structural decline evident with increasing age. To date, there have been a number of clinical trials in older adults whereby chronic supplementation with B vitamins, omega-3 fatty acids, or resveratrol, has been observed to either slow the rate of decline or repair cerebral tissue. There is also some evidence from animal studies indicating that supplementation with glycerophospholipids (GPL) may benefit cerebral structure, though these effects have not yet been investigated in adult humans. Despite this paucity of research, there are a number of factors predicting poorer cerebral structure in older humans, which GPL supplementation appears to beneficially modify or protect against. These include elevated concentrations of homocysteine, unbalanced activity of reactive oxygen species both increasing the risk of oxidative stress, increased concentrations of pro-inflammatory messengers, as well as poorer cardio- and cerebrovascular function. As such, it is hypothesized that GPL supplementation will support cerebral structure in older adults. These cerebral effects may influence cognitive function. The current review aims to provide a theoretical basis for future clinical trials investigating the effects of GPL supplementation on cerebral structural integrity in older adults.

Complex Relation Between Diet and Phospholipid Fatty Acids in Children With Cystic Fibrosis

OBJECTIVES

Altered total plasma n-6 and n-3 fatty acids are common in cystic fibrosis (CF). Whether alterations extend to plasma phosphatidylcholine (PC) and phosphatidylethanolamine (PE) and are explained by diet is unclear. The present study was to describe the dietary intake of a large group of children with CF and to determine whether dietary fat composition explains differences in plasma PC and PE fatty acids between children with and without CF.

METHODS

Dietary intake was assessed using a food frequency questionnaire. Venous blood was collected. Plasma PC and PE were separately analyzed for fatty acids.

RESULTS

Children with CF, n = 74, consumed more calories and fat (g/day and % energy), with significantly more saturates mainly from dairy foods and less polyunsaturates including linoleic acid (LA), arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) (% fat) than reference children, n = 71. A subset of children with CF, not differing in dietary intake from the larger group, had significantly lower LA and DHA, but higher EPA in plasma PC and had higher LA and lower ARA and DHA in plasma PE, compared to a subset of reference children. In both groups, LA intake and LA in plasma PC and PE were not associated. EPA and DHA intakes were positively associated with EPA and DHA, respectively, in plasma PC, but not PE, in reference children only.

CONCLUSIONS

The fatty acid composition of plasma PC and PE is altered in CF. Fatty acid differences between children with and without CF are inconsistent between PC and PE and are not explained by dietary fat.

Determinants of Serum Glycerophospholipid Fatty Acids in Cystic Fibrosis

The etiology of altered blood fatty acid (FA) composition in cystic fibrosis (CF) is understood only partially. We aimed to investigate the determinants of serum glycerophospholipids’ FAs in CF with regard to the highest number of FAs and in the largest cohort to date. The study comprised 172 CF patients and 30 healthy subjects (HS). We assessed Fas’ profile (gas chromatography/mass spectrometry), CF transmembrane conductance regulator (CFTR) genotype, spirometry, fecal elastase-1, body height and weight Z-scores, liver disease, diabetes and colonization by Pseudomonas aeruginosa. The amounts of saturated FAs (C14:0, C16:0) and monounsaturated FAs (C16:1n-7, C18:1n-9, C20:1n-9, C20:3n-9) were significantly higher in CF patients than in HS. C18:3n-6, C20:3n-6 and C22:4n-6 levels were also higher in CF, but C18:2n-6, C20:2n-6 and C20:4n-6, as well as C22:6n-3, were lower. In a multiple regression analysis, levels of seven FAs were predicted by various sets of factors that included age, genotype, forced expiratory volume in one second, pancreatic status and diabetes. FA composition abnormalities are highly prevalent in CF patients. They seem to be caused by both metabolic disturbances and independent clinical risk factors. Further research into the influence of CFTR mutations on fat metabolism and desaturases’ activity is warranted.

Choline Supplementation With a Structured Lipid in Children With Cystic Fibrosis: A Randomized Placebo-Controlled Trial

BACKGROUND

Choline depletion is seen in cystic fibrosis (CF) and pancreatic insufficiency in spite of enzyme treatment and may result in liver, fatty acid, and muscle abnormalities. This study evaluated the efficacy and safety of an easily absorbed choline-rich structured lipid (LYM-X-SORB™ [LXS]) to improve choline status.

METHODS

Children with CF and pancreatic insufficiency were randomized to LXS or placebo in a 12-month double blind trial. Dietary choline intake, plasma cholines, plasma and fecal phospholipids, coefficient of fat absorption, pulmonary function, growth status, body composition, and safety measures were assessed. Magnetic resonance spectroscopy for calf muscle choline and liver fat were assessed in a subgroup and compared with a healthy comparison group matched for age, sex, and body size.

RESULTS

A total of 110 subjects were enrolled (age 10.4 ± 3.0 years). Baseline dietary choline, 88% recommended, increased 3-fold in the LXS group. Plasma choline, betaine, and dimethylglycine increased in the LXS but not placebo (P = 0.007). Plasma lysophosphatidylcholine and phosphatidylcholine increased, and fecal phosphatidylcholine/phosphatidylethanolamine ratio decreased (P ≤ 0.05) in LXS only, accompanied by a 6% coefficient of fat absorption increase (P = 0.001). Children with CF had higher liver fat than healthy children and depleted calf muscle choline at baseline. Muscle choline concentration increased in LXS and was associated with improvement in plasma choline status. No relevant changes in safety measures were evident.

CONCLUSIONS

LXS had improved choline intake, plasma choline status, and muscle choline stores compared with placebo group. The choline-rich supplement was safe, accepted by participants, and improved choline status in children with CF.

Arachidonic acid needed in infant formula when docosahexaenoic acid is present

Recently, the European Food Safety Authority asserted that arachidonic acid (ARA) is an optional nutrient for the term infant even when docosahexaenoic acid (DHA) is present. The brief rationale is based on an explicit, widespread misapplication of the concept of "essential fatty acids" to linoleic acid that implies it is uniquely required as a nutrient per se. Linoleic acid prevents acute clinical symptoms caused by polyunsaturated fatty acid-deficient diets and is the major precursor for ARA in most human diets. Experimental diets with ARA as the sole n-6 similarly prevent symptoms but at a lower energy percentage than linoleic acid and show ARA is a precursor for linoleic acid. The absence of consistent evidence of ARA benefit from randomized controlled trials is apparently an issue as well. This review highlights basic and clinical research relevant to ARA requirements as an adjunct to DHA in infancy. ARA is a major structural central nervous system component, where it rapidly accumulates perinatally and is required for signaling. Tracer studies show that ARA-fed infants derive about half of their total body ARA from dietary preformed ARA. Clinically, of the 3 cohorts of term infants studied with designs isolating the effects of ARA (DHA-only vs DHA+ARA), none considered ARA-specific outcomes such as vascular or immune function; the study with the highest ARA level showed significant neurocognitive benefit. All breastfed term infants of adequately nourished mothers consume both DHA and ARA. The burden of proof to substantially deviate from the composition of breastmilk is greater than that available from inherently empirical human randomized controlled trial evidence. Infant formulas with DHA but without ARA risk harm from suppression of ARA-mediated metabolism manifest among the many unstudied functions of ARA.

Choline supplementation alters some amino acid concentrations with no change in homocysteine in children with cystic fibrosis and pancreatic insufficiency

The present study determined the plasma amino acid status in children with cystic fibrosis (CF) and pancreatic insufficiency (PI) in the modern medical and nutritional care setting and investigated the effect of choline supplementation on amino acid status. A total of 110 children aged 5 to 18 years with CF and PI were randomized to receive choline-enriched structured lipid (LYM-X-SORB) or placebo with similar energy and fat content. Plasma amino acids were measured at baseline and 3 and 12 months. We hypothesized that choline supplementation would result in lower plasma homocysteine concentrations in children with CF. At baseline, dietary protein intake was high and the amino acid profile was within laboratory reference ranges in most participants. Alanine and cysteine were elevated in 24% and 36% of participants, respectively. Children with baseline alanine above reference range had improved weight, body mass index, and fat-free mass. Low homocysteine was found in 62% of children 11 years and older. After 3 and 12 months, there was no effect of choline supplementation on methionine or homocysteine status. Compared with placebo, choline supplementation resulted in increased glycine and decreased threonine, histidine, valine, and total branch chained amino acids at 12 months. In conclusion, daily choline supplementation with LYM-X-SORB did not alter methionine-homocysteine metabolism but did result in alterations in other amino acids in children with CF and PI.

Role of S-adenosylhomocysteine in cardiovascular disease and its potential epigenetic mechanism

Transmethylation reactions utilize S-adenosylmethionine (SAM) as a methyl donor and are central to the regulation of many biological processes: more than fifty SAM-dependent methyltransferases methylate a broad spectrum of cellular compounds including DNA, histones, phospholipids and other small molecules. Common to all SAM-dependent transmethylation reactions is the release of the potent inhibitor S-adenosylhomocysteine (SAH) as a by-product. SAH is reversibly hydrolyzed to adenosine and homocysteine by SAH hydrolase. Hyperhomocysteinemia is an independent risk factor for cardiovascular disease. However, a major unanswered question is if homocysteine is causally involved in disease pathogenesis or simply a passive and indirect indicator of a more complex mechanism. A chronic elevation in homocysteine levels results in a parallel increase in intracellular or plasma SAH, which is a more sensitive biomarker of cardiovascular disease than homocysteine and suggests that SAH is a critical pathological factor in homocysteine-associated disorders. Previous reports indicate that supplementation with folate and B vitamins efficiently lowers homocysteine levels but not plasma SAH levels, which possibly explains the failure of homocysteine-lowering vitamins to reduce vascular events in several recent clinical intervention studies. Furthermore, more studies are focusing on the role and mechanisms of SAH in different chronic diseases related to hyperhomocysteinemia, such as cardiovascular disease, kidney disease, diabetes, and obesity. This review summarizes the current role of SAH in cardiovascular disease and its effect on several related risk factors. It also explores possible the mechanisms, such as epigenetics and oxidative stress, of SAH. This article is part of a Directed Issue entitled: Epigenetic dynamics in development and disease.

Sequential bilateral central retinal vein occlusions in a cystic fibrosis patient with hyperhomocysteinemia and hypergamma-globulinemia

PURPOSE

To report a case of sequential bilateral central retinal vein occlusions in a cystic fibrosis patient with hyperhomocysteinemia and hypergamma-globulinemia over 6 years of follow up.

METHODS

Observational case report of one patient.

RESULTS

A 31 year-old male with a history of cystic fibrosis presented with a central retinal vein occlusion (CRVO) in his left eye, followed by a CRVO in his right eye 4 years later. His medical workup was significant for elevated levels of homocysteine and gamma-globulins, which coincided with initiation of intravenous immunoglobulin (IVIG) proceeding his second CRVO.

CONCLUSIONS

We describe a case of sequential bilateral central retinal vein occlusions in a cystic fibrosis patient with hyperhomocysteinemia and hypergamma-globulinemia over 6 years of follow up and discuss the important role of these risk factors in retinal venous occlusive disease.

Inflammation, oxidative stress, and cardiovascular disease risk factors in adults with cystic fibrosis

Cystic fibrosis (CF) represents one of a number of localized lung and non-lung diseases with an intense chronic inflammatory component associated with evidence of systemic oxidative stress. Many of these chronic inflammatory diseases are accompanied by an array of atherosclerotic processes and cardiovascular disease (CVD), another condition strongly related to inflammation and oxidative stress. As a consequence of a dramatic increase in long-lived patients with CF in recent decades, the specter of CVD must be considered in these patients who are now reaching middle age and beyond. Buttressed by recent data documenting that CF patients exhibit evidence of endothelial dysfunction, a recognized precursor of atherosclerosis and CVD, the spectrum of risk factors for CVD in CF is reviewed here. Epidemiological data further characterizing the presence and extent of atherogenic processes in CF patients would seem important to obtain. Such studies should further inform and offer mechanistic insights into how other chronic inflammatory diseases potentiate the processes leading to CVDs.

Red blood cell folate levels in pregnant women with a history of mood disorders: a case series

BACKGROUND

Maternal folate supplementation reduces offspring risk for neural tube defects (NTDs) and other congenital abnormalities. Maternal red blood cell (RBC) folate concentrations of >906 nmol/L have been associated with the lowest risk of having a neural tube defect affected pregnancy. Mood disorders (e.g., depression, bipolar disorder) are common among women and can be associated with folate deficiency. Thus, pregnant women with histories of mood disorders may be prone to RBC folate levels insufficient to provide optimal protection against neural tube defects. Although previous studies have assessed RBC folate concentrations in pregnant women from the general population, none have looked specifically at a group of pregnant women who have a history of a mood disorder.

METHODS

We collected data about RBC folate concentrations and folic acid supplement intake during early pregnancy (<161 days gestation) from n = 24 women with histories of mood disorders. We also collected information about offspring congenital abnormalities and birth weight.

RESULTS

Among women with histories of mood disorders, the mean RBC folate concentration was 674 nmol/L (range, 362-1105 nmol/L). Only 12.5% (n = 3) of the women had RBC folate concentrations >906 nmol/L, despite all participants reporting current daily use of folic acid supplements. Data regarding offspring were available for 22 women: birth weights ranged from 2296 g to 4819 g, and congenital abnormalities were identified in two (hypoplastic left heart, annular pancreas).

CONCLUSION

Data from this exploratory case series suggest a need for future larger scale controlled studies investigating RBC folate concentrations in early pregnancy and offspring outcomes among women with and without histories of mood disorders.

Thin-layer chromatography of phospholipids

Thin-layer chromatography (TLC) is a technique that has been routinely used for the separation and identification of lipids. Here we describe an optimized protocol for the steady state labeling, separation, and quantification of yeast phospholipids using 1-D TLC.

S-adenosyl-L-homocysteine hydrolase and methylation disorders: yeast as a model system

S-adenosyl-L-methionine (AdoMet)-dependent methylation is central to the regulation of many biological processes: more than 50 AdoMet-dependent methyltransferases methylate a broad spectrum of cellular compounds including nucleic acids, proteins and lipids. Common to all AdoMet-dependent methyltransferase reactions is the release of the strong product inhibitor S-adenosyl-L-homocysteine (AdoHcy), as a by-product of the reaction. S-adenosyl-L-homocysteine hydrolase is the only eukaryotic enzyme capable of reversible AdoHcy hydrolysis to adenosine and homocysteine and, thus, relief from AdoHcy inhibition. Impaired S-adenosyl-L-homocysteine hydrolase activity in humans results in AdoHcy accumulation and severe pathological consequences. Hyperhomocysteinemia, which is characterized by elevated levels of homocysteine in blood, also exhibits a similar phenotype of AdoHcy accumulation due to the reversal of the direction of the S-adenosyl-L-homocysteine hydrolase reaction. Inhibition of S-adenosyl-L-homocysteine hydrolase is also linked to antiviral effects. In this review the advantages of yeast as an experimental system to understand pathologies associated with AdoHcy accumulation will be discussed.

Homocysteine as a risk factor for atherosclerosis: is its conversion to s-adenosyl-L-homocysteine the key to deregulated lipid metabolism?

Homocysteine (Hcy) has been recognized for the past five decades as a risk factor for atherosclerosis. However, the role of Hcy in the pathological changes associated with atherosclerosis as well as the pathological mechanisms triggered by Hcy accumulation is poorly understood. Due to the reversal of the physiological direction of the reaction catalyzed by S-adenosyl-L-homocysteine hydrolase Hcy accumulation leads to the synthesis of S-adenosyl-L-homocysteine (AdoHcy). AdoHcy is a strong product inhibitor of S-adenosyl-L-methionine (AdoMet)-dependent methyltransferases, and to date more than 50 AdoMet-dependent methyltransferases that methylate a broad spectrum of cellular compounds including nucleic acids, proteins and lipids have been identified. Phospholipid methylation is the major consumer of AdoMet, both in mammals and in yeast. AdoHcy accumulation induced either by Hcy supplementation or due to S-adenosyl-L-homocysteine hydrolase deficiency results in inhibition of phospholipid methylation in yeast. Moreover, yeast cells accumulating AdoHcy also massively accumulate triacylglycerols (TAG). Similarly, Hcy supplementation was shown to lead to increased TAG and sterol synthesis as well as to the induction of the unfolded protein response (UPR) in mammalian cells. In this review a model of deregulation of lipid metabolism in response to accumulation of AdoHcy in Hcy-associated pathology is proposed.

Plasma choline depletion is associated with decreased peripheral blood leukocyte acetylcholine in children with cystic fibrosis

BACKGROUND

Choline is an important constituent of acetylcholine. Choline is needed for acetylcholine in the nonneuronal acetylcholine system that includes epithelial cells of the lung and intestine, endothelial cells, and immune cells. Plasma free choline concentrations are low in children with cystic fibrosis (CF), but the implications for acetylcholine are unknown.

OBJECTIVE

We determined the relation between plasma free choline and related metabolites and leukocyte acetylcholine in children with CF and in a control group of healthy children without CF.

DESIGN

This was a cross-sectional study in 34 children with CF who were pancreatic insufficient and taking pancreatic enzyme-replacement therapy and in 16 healthy children. Plasma free choline, betaine, dimethylglycine, methionine, homocysteine, and leukocyte acetylcholine concentrations were quantified by using isotope-dilution HPLC-tandem mass spectrometry.

RESULTS

Mean (±SE) plasma free choline was 9.30 ± 0.37 and 6.54 ± 0.38 μmol/L (P < 0.05) and leukocyte acetylcholine was 1.21 ± 0.016 and 0.077 ± 0.011 pmol leukocyte acetylcholine/10(6) cells (P < 0.05) in control children and children with CF, respectively. Leukocyte acetylcholine was positively correlated with plasma free choline concentration in children with CF (r = 0.412, P < 0.05) but not in control children. Plasma betaine, dimethylglycine, and methionine concentrations were also lower in children with CF than in control children (P < 0.05).

CONCLUSIONS

A low free choline and methyl status in children with CF is associated with reduced acetylcholine in leukocytes. Whether these changes are explained by a mutation in the CF transmembrane conductance regulator or disturbances in choline metabolism and the implications for immune cell dysfunction in CF are unknown. This trial was registered at clinicaltrials.gov as NCT01150136.

Effects of S-adenosylhomocysteine and homocysteine on DNA damage and cell cytotoxicity in murine hepatic and microglia cell lines

Limited research has been performed on S-adenosylhomocysteine (SAH) or homocysteine (Hcy)-evoked cell damage in hepatic and neuronal cells. In this study, we assessed effects of SAH or Hcy on cell cytotoxicity and DNA damage in hepatic and neuronal cells and attempted to find the underlying mechanism. Cell cytotoxicity and DNA damage were evaluated in murine hepatic cells (BNL CL.2 cell line) and microglia cells (BV-2 cell line) with SAH or Hcy treatment for 48 h. The influences of SAH or Hcy on lipid peroxidation and DNA methylation were also measured in both cell lines. SAH (5-20 microM) or Hcy (1-5 mM) dose dependently inhibited cell cytotoxicity and enhanced DNA damage in both types of cells. Furthermore, SAH treatment markedly increased intracellular SAH levels and DNA hypomethylation, whereas Hcy caused minimal effects on these two parameters at much higher concentrations. Hcy significantly induced lipid peroxidation, but not SAH. The present results show that SAH might cause cellular DNA damage in hepatic and microglia cells by DNA hypomethylation, resulting in irreversible DNA damage and increased cell cytotoxicity. In addition, higher Hcy could induce cellular DNA damage through increased lipid peroxidation and DNA hypomethylation. We suggest that SAH is a better marker of cell damage than Hcy in hepatic and microglia cells.

Bile salt-phospholipid conjugate ursodeoxycholyl lysophosphatidylethanolamide as a hepatoprotective agent

A decrease of hepatocellular phosphatidylcholine (PC) is associated with hepatic injury, e.g., in nonalcoholic steatohepatitis (NASH). Therefore, we evaluated the hepatoprotective effect of a PC-precursor lipid specifically targeted to the liver. We synthesized the bile acid-phospholipid conjugate ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE), which was designed to target PC to hepatocytes by way of bile-acid transport systems. We synthesized a fluorescently labeled analogue UDCA-6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]hexanoyl PE (UDCA-NBDPE) for uptake and metabolism studies. Unexpectedly, the majority of UDCA-NBDPE was still intact and not hydrolyzed efficiently in HepG2 cells. For targeting in vivo, NBD fluorescence from UDCA-NBDPE-injected mice was recovered in the liver the most, whereas injection of NBDPE alone resulted in an even distribution in liver, kidneys, and intestine. Cytoprotection by UDCA-LPE was tested in starvation and tumor necrosis factor alpha (TNF-alpha) apoptosis models using HepG2 cells. Only the intact UDCA-LPE was able to persistently stimulate growth after 36 to 120-hour starvation, and significantly inhibited TNF-alpha-induced apoptosis. In both models, LPC, LPE, UDCA, or UDCA added with LPE exhibited weak to no cytoprotection. UDCA-LPE stabilized mitochondrial membranes by lowering mitochondrial membrane potential. Western blot analyses of phosphorylated Akt and glycogen synthase kinase-3 (GSK-3)alpha/beta revealed that UDCA-LPE activated phosphatidyl inositol 3-kinase (PI3K)/Akt signaling pathways. The PI3K inhibitor LY294002 or Akt small interfering (si)RNA consistently inhibited the proproliferative effects of UDCA-LPE during starvation. The TNF-alpha death-receptor extrinsic pathway involves caspase 8 activation, which is inhibited by cellular FLICE-inhibitory protein (cFLIP); thus, cFLIP siRNA was employed in our studies. cFLIP siRNA was able to reverse the cytoprotective effects of UDCA-LPE during TNF-alpha-induced apoptosis, and UDCA-LPE concomitantly upregulated protein expression of cFLIP(L).

CONCLUSION

UDCA-LPE, which targeted the liver in vivo, elicited potent biological activities in vitro by stimulating hepatocyte growth and by inhibiting TNF-alpha-induced apoptosis. Thus, UDCA-LPE may be suitable for evaluation of treatment efficacy in NASH.

Phthalate metabolites in urine of CF patients are associated with use of enteric-coated pancreatic enzymes

In metabolomic studies using liquid chromatography mass spectrometry of urine from children with cystic fibrosis (CF), high levels of metabolites of low molecular weight phthalates were found. Phthalate metabolite excretion was explained by therapy with enteric-coated pancreatic enzyme replacements. Phthalate metabolite identity was confirmed by tandem mass spectrometry. Pancreatic insufficient CF children taking Cotazym ECS(®), which is formulated with diethyl phthalate (DEP), had urinary metabolites of DEP. Children taking Creon(®), which has dibutyl phthalate (DBP), excreted DBP metabolites. The estimated concentrations of free MEP were 2-3 orders of magnitude higher than reported from environmental phthalate exposure. Enteric-coated pancreatic enzymes can expose individuals with CF to incessant, high oral intakes of phthalates. Although adverse effects have neither been shown to be present nor absent, we raise the need to consider that individuals requiring life-long therapy with some current pancreatic enzyme replacements chronically ingest high amounts of phthalates.

Preliminary evidence for cell membrane amelioration in children with cystic fibrosis by 5-MTHF and vitamin B12 supplementation: a single arm trial

Background

Cystic fibrosis (CF) is one of the most common fatal autosomal recessive disorders in the Caucasian population caused by mutations of gene for the cystic fibrosis transmembrane conductance regulator (CFTR). New experimental therapeutic strategies for CF propose a diet supplementation to affect the plasma membrane fluidity and to modulate amplified inflammatory response. The objective of this study was to evaluate the efficacy of 5-methyltetrahydrofolate (5-MTHF) and vitamin B12 supplementation for ameliorating cell plasma membrane features in pediatric patients with cystic fibrosis.

Methodology and Principal Findings

A single arm trial was conducted from April 2004 to March 2006 in an Italian CF care centre. 31 children with CF aged from 3 to 8 years old were enrolled. Exclusion criteria were diabetes, chronic infections of the airways and regular antibiotics intake. Children with CF were supplemented for 24 weeks with 5-methyltetrahydrofolate (5-MTHF, 7.5 mg /day) and vitamin B12 (0.5 mg/day). Red blood cells (RBCs) were used to investigate plasma membrane, since RBCs share lipid, protein composition and organization with other cell types. We evaluated RBCs membrane lipid composition, membrane protein oxidative damage, cation content, cation transport pathways, plasma and RBCs folate levels and plasma homocysteine levels at baseline and after 24 weeks of 5-MTHF and vitamin B12 supplementation. In CF children, 5-MTHF and vitamin B12 supplementation (i) increased plasma and RBC folate levels; (ii) decreased plasma homocysteine levels; (iii) modified RBC membrane phospholipid fatty acid composition; (iv) increased RBC K⁺ content; (v) reduced RBC membrane oxidative damage and HSP70 membrane association.

Conclusion and Significance

5-MTHF and vitamin B12 supplementation might ameliorate RBC membrane features of children with CF.

Trial Registration

ClinicalTrials.gov NCT00730509

Cystic Fibrosis and Nutrition: Linking Phospholipids and Essential Fatty Acids with Thiol Metabolism

Cystic fibrosis (CF) is the most common lethal inherited disorder among Caucasians and results from mutation in the gene encoding the CF transmembrane conductance regulator. In addition to its multisystem clinical effects, the disease is characterized by increased proinflammatory mediators and oxidant stress, and systemic redox imbalance with reduced glutathione (GSH), together with alterations in circulating and tissue (n-6) and (n-3) fatty acids, particularly a decrease in docosahexaenoic acid. The metabolism of phospholipids and fatty acids is closely related to GSH through the methionine-homocysteine cycle, in which choline via betaine provides methyl groups to regenerate S-adenosylmethionine, important in generating phosphatidylcholine and amino acid precursors for GSH. Current research focuses both on fatty acid supplementations to normalize altered (n-6) to (n-3) fatty acid balance and decrease generation of (n-6) fatty acid-derived inflammatory mediators, and strategies to improve oxidant defenses and redox balance. However, further research is needed before such strategies can be included in clinical care of individuals with CF.

Influence of Pancreatic Status and Sex on Polyunsaturated Fatty Acid Profiles in Cystic Fibrosis

Background: Some but not all studies have reported abnormal polyunsaturated fatty acid composition in cystic fibrosis (CF) patients. We investigated the influence of pancreatic status and sex on the fatty acid profile in plasma and erythrocyte membranes in patients with CF.

Methods: After a 1-step transesterification with acetyl chloride on plasma and washed erythrocyte membranes, we quantified fatty acid methyl esters by use of GC-MS in 124 CF patients and 80 age-matched healthy controls. In the CF group, mean (SD) age was 17.5 (11.3) years, and 51.6% were male. Pancreatic insufficiency was diagnosed in 78% of the CF population.

Results: A decrease in docosahexaenoic acid concentrations was observed in CF patients independently of pancreatic status. Pancreatic insufficient CF patients displayed lower concentrations of linoleic acid and arachidonic acid and higher concentrations of dihomo-γ-linolenic acid and eicosatrienoic acid (mead acid) in plasma and erythrocyte membranes compared with healthy controls and pancreatic sufficient CF patients. Male CF patients had significantly lower docosahexaenoic acid and higher eicosatrienoic acid in plasma and erythrocyte membranes compared with female CF patients.

Conclusions: These results support the concept that multiple abnormalities of polyunsaturated fatty acid composition participate in the CF disease phenotype and that pancreatic status plays a major role in such abnormalities. Moreover, patient sex influences the polyunsaturated fatty acid spectrum in CF, with more marked abnormalities in males.

Choline-related supplements improve abnormal plasma methionine-homocysteine metabolites and glutathione status in children with cystic fibrosis

BACKGROUND

Liver triacylglycerol accumulation and oxidative stress are common in cystic fibrosis (CF) and also occur in choline deficiency. Previously, we showed an association between elevated plasma homocysteine, reduced ratios of S-adenosylmethionine to S-adenosylhomocysteine (SAM:SAH) and of phosphatidylcholine to phosphatidylethanolamine, and phospholipid malabsorption in children with CF.

OBJECTIVE

The objective was to address a possible relation between altered methionine-homocysteine metabolism and choline metabolism in children with CF.

DESIGN

Children with CF were assigned without bias to supplementation with 2 g lecithin/d (n = 13), 2 g choline/d (n = 12), or 3 g betaine/d (n = 10) for 14 d. Plasma concentrations of methionine, adenosine, cysteine, cysteinyl-glycine, glutathione, glutathione disulfide (GSSG), and fatty acids; SAM:SAH; and red blood cell phospholipids were measured within each group of children with CF before and after supplementation. Plasma from healthy children without CF (n = 15) was analyzed to obtain reference data.

RESULTS

Children with CF had higher plasma homocysteine, SAH, and adenosine and lower methionine, SAM:SAH, and glutathione:GSSG than did children without CF. Supplementation with lecithin, choline, or betaine resulted in a significant increase in plasma methionine, SAM, SAM:SAH, and glutathione:GSSG and a decrease in SAH (n = 35). Supplementation with choline or betaine was associated with a significant decrease in plasma SAH and an increase in SAM:SAH, methionine, and glutathione:GSSG. Supplementation with lecithin or choline also increased plasma methionine and SAM.

CONCLUSION

We showed that dietary supplementation with choline-related compounds improves the low SAM:SAH and glutathione redox balance in children with CF.

An overview of monitoring and supplementation of omega 3 fatty acids in cystic fibrosis

Essential fatty acid deficiency has been increasingly reported in patients with cystic fibrosis. The purpose of this work is to critically summarize previous data on fatty acid status and omega3 supplementation in cystic fibrosis. Although the reported abnormalities differ from study to study, the two most consistent features appeared to be reduced circulating levels of linoleic acid and docosahexaenoic acid (DHA). On the assumption that the fatty acid composition of erythrocyte cell membranes may be similar to that of other organs, it seems appropriate to monitor the phospholipid profile from erythrocyte membranes together with circulating blood levels. Formulations containing widely variable DHA doses, ranging from 300 mg to 5 g per day, have been administered to patients with cystic fibrosis with discrepant outcomes. Randomized controlled trials are needed in order to draw firm conclusions on the therapeutic effect of omega3 fatty acid supplementation in cystic fibrosis.

Metabolic endophenotype and related genotypes are associated with oxidative stress in children with autism

Autism is a behaviorally defined neurodevelopmental disorder usually diagnosed in early childhood that is characterized by impairment in reciprocal communication and speech, repetitive behaviors, and social withdrawal. Although both genetic and environmental factors are thought to be involved, none have been reproducibly identified. The metabolic phenotype of an individual reflects the influence of endogenous and exogenous factors on genotype. As such, it provides a window through which the interactive impact of genes and environment may be viewed and relevant susceptibility factors identified. Although abnormal methionine metabolism has been associated with other neurologic disorders, these pathways and related polymorphisms have not been evaluated in autistic children. Plasma levels of metabolites in methionine transmethylation and transsulfuration pathways were measured in 80 autistic and 73 control children. In addition, common polymorphic variants known to modulate these metabolic pathways were evaluated in 360 autistic children and 205 controls. The metabolic results indicated that plasma methionine and the ratio of S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH), an indicator of methylation capacity, were significantly decreased in the autistic children relative to age-matched controls. In addition, plasma levels of cysteine, glutathione, and the ratio of reduced to oxidized glutathione, an indication of antioxidant capacity and redox homeostasis, were significantly decreased. Differences in allele frequency and/or significant gene-gene interactions were found for relevant genes encoding the reduced folate carrier (RFC 80G > A), transcobalamin II (TCN2 776G > C), catechol-O-methyltransferase (COMT 472G > A), methylenetetrahydrofolate reductase (MTHFR 677C > T and 1298A > C), and glutathione-S-transferase (GST M1). We propose that an increased vulnerability to oxidative stress (endogenous or environmental) may contribute to the development and clinical manifestations of autism.

Evidence of choline depletion and reduced betaine and dimethylglycine with increased homocysteine in plasma of children with cystic fibrosis

Cystic fibrosis (CF) is associated with many clinical complications including steatosis for which the relation to defective CF transmembrane conductance regulator protein is unclear. Choline deficiency results in hepatic steatosis. Choline is the precursor of betaine, which donates methyl groups for remethylation of homocysteine to methionine and dimethylglycine. Previously, we have shown phospholipid malabsorption and increased plasma homocysteine in children with CF. In these studies we used normal phase HPLC with tandem mass spectrometry to determine plasma choline, betaine, and dimethylglycine in children with CF (n = 34) and healthy control children without CF (n = 15). Plasma choline, betaine, and dimethylglycine were significantly lower in children with CF (means +/- SEM, 6.48 +/- 0.35, 23.8 +/- 1.49, 1.49 +/- 0.13 mumol/L, respectively) than in children without CF (8.98 +/- 0.46, 37.3 +/- 1.84, 3.01 +/- 0.17 mumol/L, respectively). Plasma choline (r = 0.373, P = 0.007) and betaine (r = 0.399, P = 0.005) were positively related to methionine, and choline was inversely related to homocysteine (r = -0.316, P = 0.03). Choline, betaine, and dimethylglycine were all significantly and positively related to the plasma S-adenosylmethionine:S-adenosylhomocysteine (SAM:SAH) ratio (r = 0.294, r = 0.377, r = 0.442, respectively; P < 0.05). The plasma choline:betaine and betaine:dimethylglycine ratios did not differ between the children with CF and the control children, suggesting no increase in betaine synthesis, or betaine-dependent remethylation of homocysteine. These studies suggest that choline depletion may contribute to increased homocysteine in children with CF. Choline depletion and altered thiol metabolism may contribute to the clinical complications associated with CF.

Is it time to reevaluate methyl balance in humans?

S-Adenosylmethionine (AdoMet) is the major biological methyl donor. AdoMet's methyl group arises both from the diet (eg, methionine, choline, and betaine) and from de novo synthesis by the process of methylneogenesis. At least 50 AdoMet-dependent methylation reactions have been identified in mammals, and genomic analyses suggest that the final number will be much higher. Such methylation reactions play major roles in biosynthesis, regulation, and detoxification. Creatine synthesis is thought to account for the use of >70% of AdoMet-derived methyl groups in humans. This is not consistent with recent studies in mice, in which the phosphatidylethanolamine methyltransferase gene was deleted (PEMT-/-). Loss of this hepatic enzyme resulted in a 50% decrease in plasma homocysteine, which suggests that it accounts for a major component of whole-body AdoMet utilization. A reexamination of human creatine metabolism showed that dietary creatine can account for as much as 50% of daily creatine requirements in nonvegetarians and, therefore, that estimates of creatine synthesis need to be reduced. We suggest that creatine synthesis is responsible for a smaller proportion of AdoMet-derived methyl groups than has been suggested and that phosphatidylcholine synthesis via phosphatidylethanolamine methyltransferase is a major consumer of these methyl groups.

Homocysteine and folate metabolism in depression

Homocysteine is a sensitive marker of folate and vitamin B12 deficiency. Numerous studies have confirmed the association between folate deficiency and depression. It is not completely understood whether homocysteine is solely a marker for folate deficiency or if it may play a more direct role in the expression of mood disorders. This review describes the biochemical, neurochemical and clinical correlations of folate deficiency and hyperhomocysteinemia in relation to depression.

Phosphatidylcholine and lysophosphatidylcholine excretion is increased in children with cystic fibrosis and is associated with plasma homocysteine, S-adenosylhomocysteine, and S-adenosylmethionine

BACKGROUND

Hepatic steatosis and fat malabsorption are common in cystic fibrosis (CF). Choline deficiency results in decreased phosphatidylcholine synthesis through the cytidine diphosphocholine-choline pathway and hepatic steatosis and in increased synthesis of phosphatidylcholine from phosphatidylethanolamine using methyl groups from S-adenosylmethionine. The intestinal absorption of phosphatidylcholine in CF is unknown.

OBJECTIVES

The objective was to determine whether excretion of choline phosphoglyceride (phosphatidylcholine and lysophosphatidylcholine) is increased in CF and whether loss of fecal choline phosphoglyceride is associated with altered plasma methionine cycle metabolites.

DESIGN

A cross-sectional study involved 53 children with CF and 18 control children without CF. Blood was collected from all participants. A subset of 18 children with CF and 8 control children provided 72-h fecal samples and 5-d food records.

RESULTS

Fat absorption was significantly lower (x+/- SEM: 86.2 +/- 1.6% and 94.1 +/- 1.2%) and excretion of fecal fat (12.9 +/- 1.7 and 3.9 +/- 0.7 g/d), phospholipid (median: 130 and 47.7 mg/d), phosphatidylcholine (19.6 and 2.1 mg/d), and lysophosphatidylcholine (60.3 and 16.9 mg/d) was significantly higher in children with CF than in control children, respectively (P < 0.05). Choline phosphoglyceride excretion was positively correlated with plasma homocysteine and S-adenosylhomocysteine and inversely related with plasma methionine (P < 0.05).

CONCLUSIONS

Choline phosphoglyceride excretion is increased in children with CF and is associated with decreased plasma methionine and increased homocysteine and S-adenosylhomocysteine. These findings suggest choline depletion and an increased choline synthesis by S-adenosylmethionine-dependent methylation in CF, as well as a metabolic link between phosphatidylcholine metabolism and the methionine-homocysteine cycle in humans.

Assessment of phospholipid malabsorption by quantification of fecal phospholipid

OBJECTIVES

The standard methods for quantifying fat absorption involve extraction of fat from fecal samples with heptane, ether and ethanol. These solvents do not quantitatively recover phospholipids. Malabsorption of dietary and biliary phosphatidylcholine could potentially result in choline deficiency. Therefore, the authors developed a method extracting and quantifying fecal phospholipids.

METHODS

Fecal samples were collected for 72 hours from 18 children with cystic fibrosis and 10 control children. Fat was extracted first with hexane/diethyl ether/ethanol and then with chloroform/methanol. Total fat was quantitated gravimetrically. Phospholipids in extracted fat were separated and quantified using high-performance liquid chromatography with evaporative light-scattering detection (HPLC-ELSD). Phospholipid quantification was validated with a phosphomolybdate colorimetric assay.

RESULTS

The combination of solvent systems used in this study significantly improved total fat (p < 0.05) and phospholipid (p < 0.001) extraction compared with either hexane/diethyl ether/ethanol or chloroform/methanol alone. Fecal phospholipid measured by HPLC-ELSD was significantly correlated with lipid-soluble phosphorous using the phosphomolybdate assay (r = 0.75, p < 0.001). This method also allows quantification of fecal phosphatidylcholine and lysophosphatidylcholine.

CONCLUSIONS

Hexane/diethyl ether/ethanol followed by chloroform/methanol extraction of fecal samples and quantification of phospholipids using HPLC-ELSD is a new method for investigating phospholipid malabsorption.