Choline metabolism provides novel insights into nonalcoholic fatty liver disease and its progression

Metabolomics insights into the modulatory effects of long-term compound polysaccharide intake in high-fat diet-induced obese rats

Background

Polysaccharides can alleviate obesity in mammals; however, studies on mechanism of this alleviation are limited. A few studies have indicated that polysaccharides improve obesity by regulating the metabolism of the body. Therefore, a metabolomics approach, consisting of high resolution nuclear magnetic resonance (NMR) spectroscopy and a multivariate statistical technique, was applied to explore the mechanism of the protective effects of lentinan and Flos Lonicera polysaccharides (LF) on high-fat diet (HFD) induced obesity.

Methods

In this study, rats were randomly divided into three groups: control diet (CD), HFD, and HFD supplemented with a mixture of lentinan and Flos Lonicera polysaccharide. Histopathological and clinical biochemical assessments were also conducted. A combination of a NMR metabolomics study and a multivariable statistical analysis method to distinguish urinary and fecal metabolites was applied.

Results

Significant obesity symptoms appeared in HFD rats (for example, significant weight gain, epididymal adipose accumulation and lipid deposition in hepatocytes), which was attenuated in the LF group. Additionally, the HFD induced a reduction of choline, citrate, pyruvate and glycerol and increased the levels of trimethylamine oxide (TMAO) and taurine. Of note, these metabolic disorders were reversed by LF intervention mainly through pathways of energy metabolism, choline metabolism and gut microbiota metabolism.

Conclusions

LF supplementation had a re-balancing effect on the disturbed metabolic pathways in the obese body. The results of this study validate the therapeutic effect of the compound polysaccharide--LF in obesity and described the biochemical and metabolic mechanisms involved.

Electronic supplementary material

The online version of this article (10.1186/s12986-018-0246-2) contains supplementary material, which is available to authorized users.

Specific enzymatic synthesis of 2,3-diaminophenazine and copper nanoclusters used for dual-emission ratiometric and naked-eye visual fluorescence sensing of choline

This work reports a novel biosensor for dual-emission ratiometric and visual fluorescence detection of choline.

Asking the Right Questions With Animal Models: Methionine- and Choline-Deficient Model in Predicting Adverse Drug Reactions in Human NASH

In the past few decades, great conceptual and technological advances have been made in the field of toxicology, but animal model-based research still remains one of the most widely used and readily available tools for furthering our current knowledge. However, animal models are not perfect in predicting all systemic toxicity in humans. Extrapolating animal data to accurately predict human toxicities remains a challenge, and researchers are obligated to question the appropriateness of their chosen animal model. This paper provides an assessment of the utility of the methionine- and choline-deficient (MCD) diet fed animal model in reflecting human nonalcoholic steatohepatitis (NASH) and the potential risks of adverse drug reactions and toxicities that are associated with the disease. As a commonly used NASH model, the MCD model fails to exhibit most metabolic abnormalities in a similar manner to the human disease. The MCD model, on the other hand, closely resembles human NASH histology and reflects signatures of drug transporter alterations in humans. Due to the nature of the MCD model, it should be avoided in studies of NASH pathogenesis, metabolic parameter evaluation, and biomarker identification. But it can be used to accurately predict altered drug disposition due to NASH-associated transporter alterations.

Prostaglandin I2 suppresses the development of diet-induced nonalcoholic steatohepatitis in mice

Nonalcoholic steatohepatitis (NASH) is a hepatic manifestation of metabolic syndrome. Although the prostaglandin (PG)I₂ receptor IP is expressed broadly in the liver, the role of PGI₂-IP signaling in the development of NASH remains to be determined. Here, we investigated the role of the PGI₂-IP system in the development of steatohepatitis using mice lacking the PGI₂ receptor IP [IP-knockout (IP-KO) mice] and beraprost (BPS), a specific IP agonist. IP-KO and wild-type (WT) mice were fed a methionine- and choline-deficient diet (MCDD) for 2, 5, or 10 wk. BPS was administered orally to mice every day during the experimental periods. The effect of BPS on the expression of chemokine and inflammatory cytokines was examined also in cultured Kupffer cells. WT mice fed MCDD developed steatohepatitis at 10 wk. IP-KO mice developed steatohepatitis at 5 wk with augmented histologic derangements accompanied by increased hepatic monocyte chemoattractant protein-1 (MCP-1) and TNF-α concentrations. After 10 wk of MCDD, IP-KO mice had greater hepatic iron deposition with prominent oxidative stress, resulting in hepatocyte damage. In WT mice, BPS improved histologic and biochemical parameters of steatohepatitis, accompanied by reduced hepatic concentration of MCP-1 and TNF-α. Accordingly, BPS suppressed the LPS-stimulated Mcp-1 and Tnf-α mRNA expression in cultured Kupffer cells prepared from WT mice. PGI₂-IP signaling plays a crucial role in the development and progression of steatohepatitis by modulating the inflammatory response, leading to augmented oxidative stress. We suggest that the PGI₂-IP system is an attractive therapeutic target for treating patients with NASH.-Kumei, S., Yuhki, K.-I., Kojima, F., Kashiwagi, H., Imamichi, Y., Okumura, T., Narumiya, S., Ushikubi, F. Prostaglandin I₂ suppresses the development of diet-induced nonalcoholic steatohepatitis in mice.

Choline Protects Against Intestinal Failure-Associated Liver Disease in Parenteral Nutrition-Fed Immature Rats

BACKGROUND

Deficiency of choline, a required nutrient, is related to intestinal failure-associated liver disease (IFALD). Therefore, we aimed to investigate the effects of choline supplementation on IFALD and the underlying mechanisms.

METHODS

Male Sprague-Dawley rats (4 weeks old) were fed AIN-93G chow and administered intravenous 0.9% saline (control), parenteral nutrition (PN), or PN plus intravenous choline (600 mg/kg) for 7 days. We evaluated body weight, hepatic histology, biochemical indicators, triglycerides, oxidative status, methylation levels of peroxisomal proliferator-activated receptor alpha (PPARα) gene promoter, expression of PPARα and carnitine palmitoyltransferase 1 (CPT1), and levels of choline metabolites.

RESULTS

The PN + choline group exhibited improved body weight compared with the PN group. PN impaired hepatic function, increased hepatic triglycerides, induced dyslipidemia, enhanced reactive oxygen species and malondialdehyde, and reduced total antioxidant capacity. The PN group had higher pathologic scores than the control group. These results were prevented by choline administration. Compared with the control group, PN increased PPARα promoter methylation and hepatic betaine concentration, reduced hepatic choline and phosphatidylcholine (PC) levels, decreased plasma choline and betaine concentrations, and downregulated PPARα and CPT1 mRNA and protein expression. Choline supplementation elevated hepatic choline and PC levels and enhanced plasma choline, betaine, and PC concentrations but reduced hepatic betaine level, reversed PPARα promoter hypermethylation, and upregulated PPARα and CPT1 mRNA and protein expression in PN-fed rats, compared with rats receiving PN alone.

CONCLUSION

Choline addition to PN may prevent IFALD by reducing oxidative stress, enhancing hepatic fat export, and promoting fatty acid catabolism in immature rats receiving PN.

Supplementary choline attenuates olive oil lipid emulsion-induced enterocyte apoptosis through suppression of CELF1/AIF pathway

Enterocyte apoptosis induced by lipid emulsions is a key cause of intestinal atrophy under total parenteral nutrition (TPN) support, and our previous work demonstrated that olive oil lipid emulsion (OOLE) could induce enterocyte apoptosis via CUGBP, Elav‐like family member 1 (CELF1)/ apoptosis‐inducing factor (AIF) pathway. As TPN‐associated complications are partially related to choline deficiency, we aimed to address whether choline supplementation could attenuate OOLE‐induced enterocyte apoptosis. Herein we present evidence that supplementary choline exhibits protective effect against OOLE‐induced enterocyte apoptosis both in vivo and in vitro. In a rat model of TPN, substantial reduction in apoptotic rate along with decreased expression of CELF1 was observed when supplementary choline was added to OOLE. In cultured Caco‐2 cells, supplementary choline attenuated OOLE‐induced apoptosis and mitochondria dysfunction by suppressing CELF1/AIF pathway. Compared to OOLE alone, the expression of CELF1 and AIF was significantly decreased by supplementary choline, whereas the expression of Bcl‐2 was evidently increased. No obvious alterations were observed in Bax expression and caspase‐3 activation. Mechanistically, supplementary choline repressed the expression of CELF1 by increasing the recruitment of CELF1 mRNA to processing bodies, thus resulting in suppression of its protein translation. Taken together, our data suggest that supplementary choline exhibits effective protection against OOLE‐induced enterocyte apoptosis, and thus, it has the potential to be used for the prevention and treatment of TPN‐induced intestinal atrophy.

Gut Microbiota and Nonalcoholic Fatty Liver Disease: Insights on Mechanisms and Therapy

The gut microbiota plays critical roles in development of obese-related metabolic diseases such as nonalcoholic fatty liver disease (NAFLD), type 2 diabetes(T2D), and insulin resistance(IR), highlighting the potential of gut microbiota-targeted therapies in these diseases. There are various ways that gut microbiota can be manipulated, including through use of probiotics, prebiotics, synbiotics, antibiotics, and some active components from herbal medicines. In this review, we review the main roles of gut microbiota in mediating the development of NAFLD, and the advances in gut microbiota-targeted therapies for NAFLD in both the experimental and clinical studies, as well as the conclusions on the prospect of gut microbiota-targeted therapies in the future.

FXR controls CHOP expression in steatohepatitis

The farnesoid X receptor (FXR) and C/EBP homologous protein (CHOP) have critical functions in hepatic lipid metabolism. Here, we aimed to explore a potential relationship between FXR and CHOP. We fed wild‐type (WT) and FXR KO mice a MCD diet (model of steatohepatitis) and found that Chop mRNA expression is upregulated in WT but not FXR KO mice. The absence of FXR aggravates hepatic inflammation after MCD feeding. In HepG2 cells, we found that Chop expression is regulated in a FXR/Retinoid X receptor (RXR)‐dependent manner. We identified a FXR/RXR‐binding site in the human CHOP promoter, demonstrating a highly conserved regulatory pathway. Our study shows that FXR/RXR regulates Chop expression in a mouse model of steatohepatitis, providing novel insights into pathogenesis of this disorder.

Methionine-supplemented diet affects the expression of cardiovascular disease-related genes and increases inflammatory cytokines in mice heart and liver

Some important environmental factors that influence the development of cardiovascular diseases (CVD) include tobacco, excess alcohol, and unhealthy diet. Methionine obtained from the diet participates in the synthesis of DNA, proteins, lipids and affects homocysteine levels, which is associated with the elevated risk for CVD development. Therefore, the aim of this study was to investigate the manner in which dietary methionine might affect cellular mechanisms underlying CVD occurrence. Swiss albino mice were fed either control (0.3% DL-methionine), methionine-supplemented (2% DL-methionine), or a methionine-deprived diet (0% DL-methionine) over a 10-week period. The parameters measured included plasma homocysteine concentrations, oxidative stress by reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio, levels of inflammatory cytokines IL-1ß, TNF-α, and IL-6, as well as expression of genes associated with CVD. The levels of apolipoprotein A5 (APOA5), a regulator of plasma triglycerides, were measured. The methionine-supplemented diet increased oxidative stress by lowering the GSH/GSSG ratio in heart tissues and decreased expression of the genes Apob, Ctgf, Serpinb2, Spp1, Il1b, and Sell, but elevated expression of Thbs4, Tgfb2, Ccr1, and Vegfa. Methionine-deprived diet reduced expression of Col3a1, Cdh5, Fabp3, Bax, and Hbegf and increased expression of Sell, Ccl5, Itga2, Birc3, Msr1, Bcl2a1a, Il1r2, and Selp. Methionine-deprived diet exerted pro-inflammatory consequences as evidenced by elevated levels of cytokines IL-1ß, TNF-α, and IL-6 noted in liver. Methionine-supplemented diet increased hepatic IL-6 and cardiac TNF-α. Both methionine supplementation and deprivation lowered hepatic levels of APOA5. In conclusion, data demonstrated that a methionine-supplemented diet modulated important biological processes associated with high risk of CVD development.

Choline Supplementation Normalizes Fetal Adiposity and Reduces Lipogenic Gene Expression in a Mouse Model of Maternal Obesity

Maternal obesity increases fetal adiposity which may adversely affect metabolic health of the offspring. Choline regulates lipid metabolism and thus may influence adiposity. This study investigates the effect of maternal choline supplementation on fetal adiposity in a mouse model of maternal obesity. C57BL/6J mice were fed either a high-fat (HF) diet or a control (NF) diet and received either 25 mM choline supplemented (CS) or control untreated (CO) drinking water for 6 weeks before timed-mating and throughout gestation. At embryonic day 17.5, HF feeding led to higher (p < 0.05) percent total body fat in fetuses from the HFCO group, while the choline supplemented HFCS group did not show significant difference versus the NFCO group. Similarly, HF feeding led to higher (p < 0.05) hepatic triglyceride accumulation in the HFCO but not the HFCS fetuses. mRNA levels of lipogenic genes such as Acc1, Fads1, and Elovl5, as well as the transcription factor Srebp1c that favors lipogenesis were downregulated (p < 0.05) by maternal choline supplementation in the HFCS group, which may serve as a mechanism to reduce fat accumulation in the fetal liver during maternal HF feeding. In summary, maternal choline supplementation improves indices of fetal adiposity in obese dams at late gestation.

Choline prevents fetal overgrowth and normalizes placental fatty acid and glucose metabolism in a mouse model of maternal obesity

Maternal obesity increases placental transport of macronutrients, resulting in fetal overgrowth and obesity later in life. Choline participates in fatty acid metabolism, serves as a methyl donor and influences growth signaling, which may modify placental macronutrient homeostasis and affect fetal growth. Using a mouse model of maternal obesity, we assessed the effect of maternal choline supplementation on preventing fetal overgrowth and restoring placental macronutrient homeostasis. C57BL/6J mice were fed either a high-fat (HF, 60% kcal from fat) diet or a normal (NF, 10% kcal from fat) diet with a drinking supply of either 25 mM choline chloride or control purified water, respectively, beginning 4 weeks prior to mating until gestational day 12.5. Fetal and placental weight, metabolites and gene expression were measured. HF feeding significantly (P<.05) increased placental and fetal weight in the HF-control (HFCO) versus NF-control (NFCO) animals, whereas the HF choline-supplemented (HFCS) group effectively normalized placental and fetal weight to the levels of the NFCO group. Compared to HFCO, the HFCS group had lower (P<.05) glucose transporter 1 and fatty acid transport protein 1 expression as well as lower accumulation of glycogen in the placenta. The HFCS group also had lower (P<.05) placental 4E-binding protein 1 and ribosomal protein s6 phosphorylation, which are indicators of mechanistic target of rapamycin complex 1 activation favoring macronutrient anabolism. In summary, our results suggest that maternal choline supplementation prevented fetal overgrowth in obese mice at midgestation and improved biomarkers of placental macronutrient homeostasis.

Hepatic vagus nerve regulates Kupffer cell activation via α7 nicotinic acetylcholine receptor in nonalcoholic steatohepatitis

BACKGROUND

Nonalcoholic fatty liver disease ranges from simple steatosis to nonalcoholic steatohepatitis (NASH). Kupffer cells play a central role in promoting hepatic inflammation, which leads to the development of NASH. We investigated the anti-inflammatory effect of hepatic vagus-mediated stimulation of the α7 nicotinic acetylcholine receptor (α7nAChR) on Kupffer cells in NASH pathogenesis.

METHODS

Wild-type (WT) mice undergoing hepatic vagotomy (HV) were fed a methionine- and choline-deficient (MCD) diet for 1 week. α7nAChR knockout (α7KO) chimeric mice were generated by transplanting α7KO bone marrow cells into irradiated and Kupffer cell-deleted WT recipients. Kupffer cells were isolated from WT mice and treated with α7nAChR agonist under stimulation by lipopolysaccharide and/or palmitic acid.

RESULTS

HV aggravated MCD diet-induced NASH in both steatosis and inflammation. The hepatic inflammatory response, including the upregulation of tumor necrosis factor alpha (TNFα), interleukin (IL)-12, and monocyte chemoattractant protein 1 (MCP-1), was accelerated in HV mice, accompanied by the downregulation of PPARα pathway genes. Kupffer cells were highly activated via the phosphorylation and nuclear translocation of nuclear factor-kappa B (NF-κB) in MCD diet-fed HV mice. The α7nAchR agonist suppressed the inflammatory response of primary Kupffer cells induced by lipopolysaccharide and palmitic acid by attenuating the NF-κB cascade. α7KO chimeric mice fed an MCD diet for 1 week developed advanced NASH with highly activated Kupffer cells. The hepatic expression of TNFα, IL-12, and MCP-1 was upregulated in α7KO chimeric mice, accompanied by abnormal lipid metabolism.

CONCLUSIONS

Hepatic vagus activity regulates the inflammatory response of Kupffer cells via α7nAChR in NASH development.

Time-course microarrays reveal early activation of the immune transcriptome in a choline-deficient mouse model of liver injury

AIMS

Choline-deficient diet is extensively used as a model of nonalcoholic fatty liver disease (NAFLD). In this study, we explored genes in the liver for which the expression changed in response to the choline-deficient (CD) diet.

MAIN METHODS

Male CD-1 mice were divided into two groups and fed a CD diet with or without 0.2% choline bitartrate for one or three weeks. Hepatic levels of choline metabolites were analyzed by using liquid chromatography mass spectrometry and hepatic gene expression profiles were examined by DNA microarray analysis.

KEY FINDINGS

The CD diet lowered liver choline metabolites after one week and exacerbated fatty liver between one and three weeks. We identified >300 genes whose expression was significantly altered in the livers of mice after consumption of this CD diet for one week and showed that liver gene expression profiles could be classified into six distinct groups. This study showed that STAT1 and interferon-regulated genes was up-regulated after the CD diet consumption and that the Stat1 mRNA level was negatively correlated with liver phosphatidylcholine level. Stat1 mRNA expression was actually up-regulated in isolated hepatocytes from the mouse liver with the CD diet.

SIGNIFICANCE

This study provides insight into the genomic effects of the CD diet through the Stat1 expression, which might be involved in NAFLD development.

NMR-based Metabolomics Analysis of Liver from C57BL/6 Mouse Exposed to Ionizing Radiation

The effects of ionizing radiation to human health are of great concern in the field of space exploration and for patients considering radiotherapy. However, to date, the effect of high-dose radiation on metabolism in the liver has not been clearly defined. In this study, 1H nuclear magnetic resonance (NMR)-based metabolomics combined with multivariate data analysis was applied to study the changes of metabolism in the liver of C57BL/6 mouse after whole-body gamma (3.0 and 7.8 Gy) or proton (3.0 Gy) irradiation. Principal component analysis (PCA) and orthogonal projection to latent structures analysis (OPLS) were used for classification and identification of potential biomarkers associated with exposure to gamma and proton radiation. The results show that the radiation exposed groups can be well separated from the control group. Where the same dose was received, the proton exposed group was nevertheless well separated from the gamma-exposed group, indicating that different radiation sources induce different alterations in the metabolic profile. Common among all high-dose gamma and proton exposed groups were the statistically decreased concentrations of choline, O-phosphocholine and trimethylamine N-oxide, while the concentrations of glutamine, glutathione, malate, creatinine, phosphate, betaine and 4-hydroxyphenylacetate were statistically and significantly elevated. Since these altered metabolites are associated with multiple biological pathways, the results suggest that radiation induces abnormality in multiple biological pathways. In particular, metabolites such as 4-hydroxyphenylacetate, betaine, glutamine, choline and trimethylamine N-oxide may be prediagnostic biomarkers candidates for ionizing exposure of the liver.

Metabolomic profiling distinction of human nonalcoholic fatty liver disease progression from a common rat model

OBJECTIVE

Characteristic pathological changes define the progression of steatosis to nonalcoholic steatohepatitis (NASH) and are correlated to metabolic pathways. A common rodent model of NASH is the methionine and choline deficient (MCD) diet. The objective of this study was to perform full metabolomic analyses on liver samples to determine which pathways are altered most pronouncedly in this condition in humans, and to compare these changes to rodent models of nonalcoholic fatty liver disease (NAFLD).

METHODS

A principal component analysis for all 91 metabolites measured indicated that metabolome perturbation is greater and less varied for humans than for rodents.

RESULTS

Metabolome changes in human and rat NAFLD were greatest for the amino acid and bile acid metabolite families (e.g., asparagine, citrulline, gamma-aminobutyric acid, lysine); although, in many cases, the trends were reversed when compared between species (cholic acid, betaine).

CONCLUSIONS

Overall, these results indicate that metabolites of specific pathways may be useful biomarkers for NASH progression, although these markers may not correspond to rodent NASH models. The MCD model may be useful when studying certain end points of NASH; however, the metabolomics results indicate important differences between humans and rodents in the biochemical pathogenesis of the disease.

Nutritional approaches for managing obesity-associated metabolic diseases

Obesity is an ongoing pandemic and serves as a causal factor of a wide spectrum of metabolic diseases including diabetes, fatty liver disease, and cardiovascular disease. Much evidence has demonstrated that nutrient overload/overnutrition initiates or exacerbates inflammatory responses in tissues/organs involved in the regulation of systemic metabolic homeostasis. This obesity-associated inflammation is usually at a low-grade and viewed as metabolic inflammation. When it exists continuously, inflammation inappropriately alters metabolic pathways and impairs insulin signaling cascades in peripheral tissues/organs such as adipose tissue, the liver and skeletal muscles, resulting in local fat deposition and insulin resistance and systemic metabolic dysregulation. In addition, inflammatory mediators, e.g., proinflammatory cytokines, and excessive nutrients, e.g., glucose and fatty acids, act together to aggravate local insulin resistance and form a vicious cycle to further disturb the local metabolic pathways and exacerbate systemic metabolic dysregulation. Owing to the critical role of nutrient metabolism in controlling the initiation and progression of inflammation and insulin resistance, nutritional approaches have been implicated as effective tools for managing obesity and obesity-associated metabolic diseases. Based on the mounting evidence generated from both basic and clinical research, nutritional approaches are commonly used for suppressing inflammation, improving insulin sensitivity, and/or decreasing fat deposition. Consequently, the combined effects are responsible for improvement of systemic insulin sensitivity and metabolic homeostasis.

Efficacy of docosahexaenoic acid-choline-vitamin E in paediatric NASH: a randomized controlled clinical trial

Nonalcoholic steatohepatitis (NASH), a progressive form of nonalcoholic fatty liver disease, is one of the most common hepatic diseases in children. We conducted a randomized controlled clinical trial on children with biopsy-proven NASH based on a combinatorial nutritional approach compared with placebo. Participants were assigned to lifestyle modification plus placebo or lifestyle modification plus a mix containing docosahexaenoic acid, choline, and vitamin E (DHA-CHO-VE). Forty children and adolescents participated in the entire trial. The primary outcome was the improvement of liver hyperechogenicity. Secondary outcomes included alterations of alanine aminotransferase (ALT) and other metabolic parameters. Furthermore, changes of serum bile acids (BA) and plasma fibroblast growth factor 19 (FGF19) levels were evaluated as inverse biomarkers of disease severity. At the end of the study, we observed a significant decrease in severe steatosis in the treatment group (50% to 5%, p = 0.001). Furthermore, although the anthropometric and biochemical measurements in the placebo and DHA-CHO-VE groups were comparable at baseline, at the end of the study ALT and fasting glucose levels improved only in the treatment group. Finally, we found that BA levels were not influenced whereas FGF19 levels were significantly increased by DHA-CHO-VE. The results suggest that a combination of DHA, VE, and CHO could improve steatosis and reduce ALT and glucose levels in children with NASH. However, further studies are needed to assess the impact of a DHA and VE combination on repair of liver damage in paediatric NASH.

Nonalcoholic Fatty Liver Disease, the Gut Microbiome, and Diet

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disorder in the world, yet the pathogenesis of the disease is not well elucidated. Due to the close anatomic and functional association between the intestinal lumen and the liver through the portal system, it is speculated that the gut microbiome may play a pivotal role in the pathogenesis of NAFLD. Furthermore, diet, which can modulate the gut microbiome and several metabolic pathways involved in NAFLD development, shows a potential tripartite relation between the gut, diet, and the liver. In this review, we summarize the current evidence that supports the association between NAFLD, the gut microbiome, and the role of diet.

Metabolomic Fingerprinting in the Comprehensive Study of Liver Changes Associated with Onion Supplementation in Hypercholesterolemic Wistar Rats

The consumption of functional ingredients has been suggested to be a complementary tool for the prevention and management of liver disease. In this light, processed onion can be considered as a source of multiple bioactive compounds with hepatoprotective properties. The liver fingerprint of male Wistar rats (n = 24) fed with three experimental diets (control (C), high-cholesterol (HC), and high-cholesterol enriched with onion (HCO) diets) was obtained through a non-targeted, multiplatform metabolomics approach to produce broad metabolite coverage. LC-MS, CE-MS and GC-MS results were subjected to univariate and multivariate analyses, providing a list of significant metabolites. All data were merged in order to figure out the most relevant metabolites that were modified by the onion ingredient. Several relevant metabolic changes and related metabolic pathways were found to be impacted by both HC and HCO diet. The model highlighted several metabolites (such as hydroxybutyryl carnitine and palmitoyl carnitine) modified by the HCO diet. These findings could suggest potential impairments in the energy−lipid metabolism, perturbations in the tricarboxylic acid cycle (TCA) cycle and β-oxidation modulated by the onion supplementation in the core of hepatic dysfunction. Metabolomics shows to be a valuable tool to evaluate the effects of complementary dietetic approaches directed to hepatic damage amelioration or non-alcoholic fatty liver disease (NAFLD) prevention.

Choline Deficiency Causes Colonic Type II Natural Killer T (NKT) Cell Loss and Alleviates Murine Colitis under Type I NKT Cell Deficiency

Serum levels of choline and its derivatives are lower in patients with inflammatory bowel disease (IBD) than in healthy individuals. However, the effect of choline deficiency on the severity of colitis has not been investigated. In the present study, we investigated the role of choline deficiency in dextran sulfate sodium (DSS)-induced colitis in mice. Methionine-choline-deficient (MCD) diet lowered the levels of type II natural killer T (NKT) cells in the colonic lamina propria, peritoneal cavity, and mesenteric lymph nodes, and increased the levels of type II NKT cells in the livers of wild-type B6 mice compared with that in mice fed a control (CTR) diet. The gene expression pattern of the chemokine receptor CXCR6, which promotes NKT cell accumulation, varied between colon and liver in a manner dependent on the changes in the type II NKT cell levels. To examine the role of type II NKT cells in colitis under choline-deficient conditions, we assessed the severity of DSS-induced colitis in type I NKT cell-deficient (Jα18^-/-) or type I and type II NKT cell-deficient (CD1d^-/-) mice fed the MCD or CTR diets. The MCD diet led to amelioration of inflammation, decreases in interferon (IFN)-γ and interleukin (IL)-4 secretion, and a decrease in the number of IFN-γ and IL-4-producing NKT cells in Jα18^-/- mice but not in CD1d^-/- mice. Finally, adaptive transfer of lymphocytes with type II NKT cells exacerbated DSS-induced colitis in Jα18^-/- mice with MCD diet. These results suggest that choline deficiency causes proinflammatory type II NKT cell loss and alleviates DSS-induced colitis. Thus, inflammation in DSS-induced colitis under choline deficiency is caused by type II NKT cell-dependent mechanisms, including decreased type II NKT cell and proinflammatory cytokine levels.

Methylenetetrahydrofolate Dehydrogenase 1 Polymorphisms Modify the Associations of Plasma Glycine and Serine With Risk of Acute Myocardial Infarction in Patients With Stable Angina Pectoris in WENBIT (Western Norway B Vitamin Intervention Trial)

Background—

Serine and glycine interconversion and methylenetetrahydrofolate dehydrogenase 1 (MTHFD1)–mediated 1-carbon transfer are the major sources of methyl groups for 1-carbon metabolism. Recently, plasma glycine and a common polymorphism in MTHFD1 have been associated with risk of acute myocardial infarction (AMI). It is, therefore, of interest to explore if these 2 pathways interact in relation to AMI.

Methods and Results—

A total of 2571 participants in the WENBIT (Western Norway B Vitamin Intervention Trial) undergoing coronary angiography for stable angina pectoris were studied. Associations of plasma serine and glycine concentrations with risk of AMI across 2 common and functional MTHFD1 polymorphisms ( rs2236225 and rs1076991 ) were explored in Cox regression models. During a median follow-up of 4.7 years, 212 patients (8.2%) experienced an AMI. In age- and sex-adjusted analyses, plasma glycine ( P <0.01), but not serine ( P =0.52), showed an overall association with AMI. However, interactions of MTHFD1 rs2236225 polymorphism with both plasma serine and glycine were observed ( P interaction =0.03 for both). Low plasma serine and glycine were associated with an increased risk of AMI among patients carrying the rs2236225 minor A allele. Similarly, low plasma glycine showed stronger risk relationship with AMI in the rs1076991 CC genotype carriers but weaker associations in patients carrying the minor T allele ( P interaction =0.02).

Conclusions—

Our results showed that 2 common and functional polymorphisms in the MTHFD1 gene modulate the risk associations of plasma serine and glycine with AMI. These findings emphasize the possible role of the MTHFD1 in regulating serine and glycine metabolism in relation to atherosclerotic complications.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique Identifier: NCT00354081.

Animal models of non-alcoholic fatty liver disease: current perspectives and recent advances

Non‐alcoholic fatty liver disease (NAFLD) is a continuous spectrum of diseases characterized by excessive lipid accumulation in hepatocytes. NAFLD progresses from simple liver steatosis to non‐alcoholic steatohepatitis and, in more severe cases, to liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Because of its growing worldwide prevalence, various animal models that mirror both the histopathology and the pathophysiology of each stage of human NAFLD have been developed. The selection of appropriate animal models continues to be one of the key questions faced in this field. This review presents a critical analysis of the histopathology and pathogenesis of NAFLD, the most frequently used and recently developed animal models for each stage of NAFLD and NAFLD‐induced HCC, the main mechanisms involved in the experimental pathogenesis of NAFLD in different animal models, and a brief summary of recent therapeutic targets found by the use of animal models. Integrating the data from human disease with those from animal studies indicates that, although current animal models provide critical guidance in understanding specific stages of NAFLD pathogenesis and progression, further research is necessary to develop more accurate models that better mimic the disease spectrum, in order to provide both increased mechanistic understanding and identification/testing of novel therapeutic approaches. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Choline and dimethylglycine produce superoxide/hydrogen peroxide from the electron transport chain in liver mitochondria

Here, we report that choline and dimethylglycine can stimulate reactive oxygen species (ROS) production in liver mitochondria. Choline stimulated O₂ ˙^- /H₂ O₂ formation at a concentration of 5 μm. We also observed that Complex II and III inhibitors, atpenin A5 and myxothiazol, collectively induced a 95% decrease in O₂ ˙^- /H₂ O₂ production indicating both sites serve as the main sources of ROS during choline oxidation. Dimethylglycine, an intermediate of choline oxidation, was a more effective ROS generator. Rates of production were ~ 43% higher than choline-mediated O₂ ˙^- /H₂ O₂ production. The main site for dimethylglycine-mediated ROS production was via reverse electron transfer to Complex I. Our results demonstrate that metabolism of essential metabolites involved in methionine and folic acid biosynthesis can stimulate mitochondrial ROS production.

The Potential of Metabolic Imaging

Metabolic imaging is a field of molecular imaging that focuses and targets changes in metabolic pathways for the evaluation of different clinical conditions. Targeting and quantifying metabolic changes noninvasively is a powerful approach to facilitate diagnosis and evaluate therapeutic response. This review addresses only techniques targeting metabolic pathways. Other molecular imaging strategies, such as affinity or receptor imaging or microenvironment-dependent methods are beyond the scope of this review. Here we describe the current state of the art in clinically translatable metabolic imaging modalities. Specifically, we focus on PET and MR spectroscopy, including conventional (1)H- and (13)C-MR spectroscopy at thermal equilibrium and hyperpolarized MRI. In this article, we first provide an overview of metabolic pathways that are altered in many pathologic conditions and the corresponding probes and techniques used to study those alterations. We then describe the application of metabolic imaging to several common diseases, including cancer, neurodegeneration, cardiac ischemia, and infection or inflammation.

Rumen-protected methionine compared with rumen-protected choline improves immunometabolic status in dairy cows during the peripartal period

The immunometabolic status of peripartal cows is altered due to changes in liver function, inflammation, and oxidative stress. Nutritional management during this physiological state can affect the biological components of immunometabolism. The objectives of this study were to measure concentrations of biomarkers in plasma, liver tissue, and milk, and also polymorphonuclear leukocyte function to assess the immunometabolic status of cows supplemented with rumen-protected methionine (Met) or choline (CHOL). Forty-eight multiparous Holstein cows were used in a randomized complete block design with 2×2 factorial arrangement of Met (Smartamine M, Adisseo NA, Alpharetta, GA) and CHOL (ReaShure, Balchem Inc., New Hampton, NY) level (with or without). Treatments (12 cows each) were control (CON), no Met or CHOL; CON and Met (SMA); CON and CHOL (REA); and CON and Met and CHOL (MIX). From -50 to -21d before expected calving, all cows received the same diet [1.40Mcal of net energy for lactation (NE_L)/kg of DM] with no Met or CHOL. From -21d to calving, cows received the same close-up diet (1.52Mcal of NE_L/kg of DM) and were assigned randomly to each treatment. From calving to 30d, cows were on the same postpartal diet (1.71Mcal of NE_L/kg of DM) and continued to receive the same treatments until 30d. The Met supplementation was adjusted daily at 0.08% DM of diet, and CHOL was supplemented at 60g/cow per day. Liver (-10, 7, 21, and 30d) and blood (-10, 4, 8, 20, and 30d) samples were harvested for biomarker analyses. Neutrophil and monocyte phagocytosis and oxidative burst were assessed at d 1, 4, 14, and 28d. The Met-supplemented cows tended to have greater plasma paraoxonase. Greater plasma albumin and IL-6 as well as a tendency for lower haptoglobin were detected in Met- but not CHOL-supplemented cows. Similarly, cows fed Met compared with CHOL had greater concentrations of total and reduced glutathione (a potent intracellular antioxidant) in liver tissue. Upon a pathogen challenge in vitro, blood polymorphonuclear leukocyte phagocytosis capacity and oxidative burst activity were greater in Met-supplemented cows. Overall, liver and blood biomarker analyses revealed favorable changes in liver function, inflammation status, and immune response in Met-supplemented cows.

Exercise and diet in the management of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver condition worldwide, and is projected to become the leading cause for liver transplantation in the United States as early as 2020. The mainstay of treatment remains lifestyle modification with diet and exercise recommendations, as although some pharmacological treatments such as glitazones and Vitamin E have shown benefit, there are concerns regarding long term safety. The evidence base for dietary interventions in NAFLD such as the Mediterranean diet, omega-3 polyunsaturated fatty acids and coffee is mainly derived from observational data with questionable validity. Where trials exist, they have shown benefit for surrogate outcomes such as hepatic steatosis and insulin resistance, but no trials have been conducted with salient clinical outcomes such as reduction in progression to chronic liver disease. Benefit in surrogate outcomes has also been seen for aerobic, anaerobic and combined modality exercise but it remains unclear if one type is superior. Furthermore, a reduction in sedentary time appears equally important. To provide a sound evidence base for lifestyle recommendations to people with NAFLD, longer duration trials of standardized dietary or exercise interventions, and testing various doses, types and with liver related outcomes, are essential.

Nutritional Epigenetics and the Prevention of Hepatocellular Carcinoma with Bioactive Food Constituents

Hepatocellular carcinoma (HCC) is an aggressive and life-threatening disease often diagnosed at intermediate or advanced stages, which substantially limits therapeutic approaches to its successful treatment. This indicates that the prevention of HCC may be the most promising strategy in reducing its incidence and mortality. Emerging evidence indicates that numerous nutrients and nonnutrient dietary bioactive components can reduce the occurrence and/or delay the development of HCC through modifications of deregulated epigenetic mechanisms. This review examines the existing knowledge on the epigenetic mechanism-based studies in in vitro and in vivo models of HCC on the chemopreventive potential of epigenetic food components, including dietary methyl-group donors, epigallocatechin-3-gallate, sodium butyrate, resveratrol, curcumin, and sulforaphane, on liver carcinogenesis. Future direction and potential challenges in the effective use of bioactive food constituents in the prevention of HCC are highlighted and discussed.

Short-Term Hypocaloric High-Fiber and High-Protein Diet Improves Hepatic Steatosis Assessed by Controlled Attenuation Parameter

OBJECTIVES

Non-alcoholic fatty liver disease is one of the most prevalent liver diseases and increases the risk of fibrosis and cirrhosis. Current standard treatment focuses on lifestyle interventions. The primary aim of this study was to assess the effects of a short-term low-calorie diet on hepatic steatosis, using the controlled attenuation parameter (CAP) as quantitative tool.

METHODS

In this prospective observational study, 60 patients with hepatic steatosis were monitored during a hypocaloric high-fiber, high-protein diet containing 1,000 kcal/day. At baseline and after 14 days, we measured hepatic fat contents using CAP during transient elastography, body composition with bioelectrical impedance analysis, and serum liver function tests and lipid profiles using standard clinical-chemical assays.

RESULTS

The median age was 56 years (25-78 years); 51.7% were women and median body mass index was 31.9 kg/m(2) (22.4-44.8 kg/m(2)). After 14 days, a significant CAP reduction (14.0%; P<0.001) was observed from 295 dB/m (216-400 dB/m) to 266 dB/m (100-353 dB/m). In parallel, body weight decreased by 4.6% (P<0.001), of which 61.9% was body fat. In addition, liver stiffness (P=0.002), γ-GT activities, and serum lipid concentrations decreased (all P<0.001).

CONCLUSIONS

This study shows for the first time that non-invasive elastography can be used to monitor rapid effects of dietary treatment for hepatic steatosis. CAP improvements occur after only 14 days on short-term low-calorie diet, together with reductions of body composition parameters, serum lipids, and liver enzymes, pointing to the dynamics of hepatic lipid turnover.

Metabolic characterization of the natural progression of chronic hepatitis B

Background

Worldwide, over 350 million people are chronically infected with the hepatitis B virus (HBV) and are at increased risk of developing progressive liver diseases. The confinement of HBV replication to the liver, which also acts as the central hub for metabolic and nutritional regulation, emphasizes the interlinked nature of host metabolism and the disease. Still, the metabolic processes operational during the distinct clinical phases of a chronic HBV infection—immune tolerant, immune active, inactive carrier, and HBeAg-negative hepatitis phases—remains unexplored.

Methods

To investigate this, we conducted a targeted metabolomics approach on serum to determine the metabolic progression over the clinical phases of chronic HBV infection, using patient samples grouped based on their HBV DNA, alanine aminotransferase, and HBeAg serum levels.

Results

Our data illustrate the strength of metabolomics to provide insight into the metabolic dysregulation experienced during chronic HBV. The immune tolerant phase is characterized by the speculated viral hijacking of the glycerol-3-phosphate–NADH shuttle, explaining the reduced glycerophospholipid and increased plasmalogen species, indicating a strong link to HBV replication. The persisting impairment of the choline glycerophospholipids, even during the inactive carrier phase with minimal HBV activity, alludes to possible metabolic imprinting effects. The progression of chronic HBV is associated with increased concentrations of very long chain triglycerides together with citrulline and ornithine, reflective of a dysregulated urea cycle peaking in the HBV envelope antigen-negative phase.

Conclusions

The work presented here will aid in future studies to (i) validate and understand the implication of these metabolic changes using a thorough systems biology approach, (ii) monitor and predict disease severity, as well as (iii) determine the therapeutic value of the glycerol-3-phosphate–NADH shuttle.

Electronic supplementary material

The online version of this article (doi:10.1186/s13073-016-0318-8) contains supplementary material, which is available to authorized users.

Effects of dietary milk- and soya-phospholipids on lipid-parameters and other risk indicators for cardiovascular diseases in overweight or obese men - two double-blind, randomised, controlled, clinical trials

The present study examined the effect of milk phospholipids (milk-PL) on lipid metabolism and on other risk factors for CVD, in comparison with milk fat (control) or soya phospholipids (soya-PL), respectively. Two double-blind parallel-group intervention trials were conducted in overweight or obese male subjects. In the first trial (trial 1), sixty-two men consumed milk enriched with either 2 g milk-PL or 2 g milk fat (control) for 8 weeks. In trial 2, fifty-seven men consumed milk enriched with either 3 g milk-PL or 2·8 g soya-PL for 7 weeks. In trial 1, milk-PL as compared with control reduced waist circumference but did not affect plasma lipids (total, HDL- and LDL-cholesterol, total cholesterol:HDL-cholesterol ratio, TAG, phospholipids), apoB, apoA1, glucose, insulin, insulin sensitivity index, C-reactive protein, IL-6, soluble intracellular adhesion molecule and total homocysteine (tHcy). Serum activities of alanine transaminase and aspartate transaminase were not changed. Activity of γ-glutamyl transferase (GGT), a marker of fatty liver, increased in the control but not in the milk-PL group, with a significant intervention effect. In trial 2, milk-PL as compared with soya-PL did not affect the above-mentioned parameters, but decreased GGT. Subjects with the methylenetetrahydrofolate reductase mutations CT and TT had 11 % (P < 0·05) higher baseline tHcy concentrations than those with the wild-type CC. However, genotype did not modulate the phospholipid intervention effect on tHcy. In conclusion, supplementation with milk-PL as compared with control fat reduced waist circumference and, as compared with both control fat and soya-PL, GGT activity.

Effects of Choline on DNA Methylation and Macronutrient Metabolic Gene Expression in In Vitro Models of Hyperglycemia

Choline is an essential nutrient that plays an important role in lipid metabolism and DNA methylation. Studies in rodents suggest that choline may adversely affect glycemic control, yet studies in humans are lacking. Using the human hepatic and placental cells, HepG2 and BeWo, respectively, we examined the interaction between choline and glucose treatments. In HepG2 cells, choline supplementation (1 mM) increased global DNA methylation and DNA methyltransferase expression in both low-glucose (5 mM) and high-glucose (35 mM) conditions. Choline supplementation increased the expression of peroxisomal acyl-coenzyme A oxidase 1 (ACOX1), which mediates fatty acid β-oxidation, especially in the high-glucose condition. High-glucose exposure increased the transcription of the gluconeogenic gene phosphoenolpyruvate carboxykinase (PEPCK), while choline supplementation mitigated such increase. Compared to HepG2 cells, the placenta-derived BeWo cells were relatively unresponsive to either high-glucose or -choline treatment. In conclusion, choline and glucose interacted to affect macronutrient metabolic genes, yet there was no indication that choline may worsen glycemic control in these in vitro human cell culture models.

Gut Microbiota and Lifestyle Interventions in NAFLD

The human digestive system harbors a diverse and complex community of microorganisms that work in a symbiotic fashion with the host, contributing to metabolism, immune response and intestinal architecture. However, disruption of a stable and diverse community, termed "dysbiosis", has been shown to have a profound impact upon health and disease. Emerging data demonstrate dysbiosis of the gut microbiota to be linked with non-alcoholic fatty liver disease (NAFLD). Although the exact mechanism(s) remain unknown, inflammation, damage to the intestinal membrane, and translocation of bacteria have all been suggested. Lifestyle intervention is undoubtedly effective at improving NAFLD, however, not all patients respond to these in the same manner. Furthermore, studies investigating the effects of lifestyle interventions on the gut microbiota in NAFLD patients are lacking. A deeper understanding of how different aspects of lifestyle (diet/nutrition/exercise) affect the host-microbiome interaction may allow for a more tailored approach to lifestyle intervention. With gut microbiota representing a key element of personalized medicine and nutrition, we review the effects of lifestyle interventions (diet and physical activity/exercise) on gut microbiota and how this impacts upon NAFLD prognosis.

Gut Microbiota and Nonalcoholic Fatty Liver Disease: Insights on Mechanism and Application of Metabolomics

Gut microbiota are intricately involved in the development of obesity-related metabolic diseases such as nonalcoholic fatty liver disease (NAFLD), type 2 diabetes, and insulin resistance. In the current review, we discuss the role of gut microbiota in the development of NAFLD by focusing on the mechanisms of gut microbiota-mediated host energy metabolism, insulin resistance, regulation of bile acids and choline metabolism, as well as gut microbiota-targeted therapy. We also discuss the application of a metabolomic approach to characterize gut microbial metabotypes in NAFLD.

NMR-based metabonomics for understanding the influence of dormant female genital tuberculosis on metabolism of the human endometrium

STUDY QUESTION

Does investigation of metabolic perturbations in endometrial tissue of women with dormant genital tuberculosis (GTB) during the window of implantation (WOI) assist in improving the understanding of endometrial receptivity?

SUMMARY ANSWER

In dormant GTB cases significant alterations in endometrial tissue metabolites occur, largely related to energy metabolism and amino acid biosynthesis in dormant GTB cases.

WHAT IS KNOWN ALREADY

As an intracellular pathogen, Mycobacterium tuberculosis strongly influences the metabolism of host cells causing metabolic dysregulation. It is also accepted that dormant GTB impairs the receptive status of the endometrium. Global metabolic profiling is useful for an understanding of disease progression and distinguishing between diseased and non-diseased groups.

STUDY DESIGN, SIZE, DURATION

Endometrial tissue samples were collected from patients reporting at the tertiary infertility care center during the period September 2011-March 2013. Women having tested positive for GTB were considered as the study group (n = 24). Normal healthy women undergoing sterilization (n = 26) and unexplained infertile women with repeated IVF failure (n = 21) volunteered to participate as controls.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Endometrial tissue samples were collected 6-10 days after confirmation of ovulation. PCR and BACTEC-460 culture were used for diagnosing GTB. Proton nuclear magnetic resonance (1H NMR) spectra of tissue were recorded using a 700 MHz Bruker Avance AV III spectrometer. Following phase and baseline correction of all NMR spectra by Bruker Topspin 2.1 software, spectral peak alignment of the data was performed. Multivariate analysis was applied to all spectra and individual metabolites identified and multiple correlation analysis was performed.

MAIN RESULTS AND THE ROLE OF CHANCE

Leucine, isoleucine, acetate, lactate, glutamate, glutamine, methionine, lysine, creatine, glycogen, glycine, proline and choline were found to be significantly increased (P < 0.05) in endometrial tissue of women with dormant GTB compared with unexplained infertile women with repeated implantation failure. Valine, citrate, succinate and aspartate were also observed to be significantly up-regulated (P < 0.01). Furthermore, a significant decrease in glucose (P < 0.05), threonine (P < 0.05), tyrosine (P < 0.01) and phenylalanine (P < 0.0001) was observed in women with dormant GTB. Pearson's correlation analysis between the expression of various endometrial receptivity markers and metabolites showed a significant negative correlation (-0.236 to -0.545, P < 0.05). Also, the metabolites were positively correlated with endometrial receptivity markers (0.207 to 0.618, P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

It is often difficult to diagnose dormant GTB because it tends to exist without any clinical signs or symptoms. In addition, the diagnosis of GTB by culture remains a challenge due to low detection rates and its paucibacillary nature. Testing for prostate-specific antigen or the Y chromosome in order to account for the possible influences of recent exposure to semen on endometrial metabolism would be important.

WIDER IMPLICATIONS OF THE FINDINGS

The metabolic changes associated with the dormant tubercle infection are of potential relevance to clinicians for the treatment of dormant GTB-related infertility.

STUDY FUNDING/COMPETING INTERESTS

Government of India, Indian Council of Medical Research. There are no conflicts of interest.

Prebiotics: Definition and protective mechanisms

The increase in chronic metabolic and immunologic disorders in the modern society is linked to major changes in the dietary patterns. These chronic conditions are associated with intestinal microbiota dysbiosis where important groups of carbohydrate fermenting, short-chain fatty acids-producing bacteria are reduced. Dietary prebiotics are defined as a selectively fermented ingredients that result in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health. Application of prebiotics may then restore the gut microbiota diversity and activity. Unlike the previously accepted prebiotics definition, where a limited number of bacterial species are involved in the prebiotic activity, new data from community-wide microbiome analysis demonstrated a broader affect of the prebiotics on the intestinal microbiota. These new findings require a revision of the current definition. In addition, prebiotics may exert immunomodulatory effects through microbiota-independent mechanisms that will require future investigations involving germ-free animal disease models.

Associations of gut-flora-dependent metabolite trimethylamine-N-oxide, betaine and choline with non-alcoholic fatty liver disease in adults

Many studies suggest that trimethylamine-N-oxide (TMAO), a gut-flora-dependent metabolite of choline, contributes to the risk of cardiovascular diseases, but little is known for non-alcoholic fatty liver disease (NAFLD). We examined the association of circulating TMAO, choline and betaine with the presence and severity of NAFLD in Chinese adults. We performed a hospital-based case-control study (CCS) and a cross-sectional study (CSS). In the CCS, we recruited 60 biopsy-proven NAFLD cases and 35 controls (18–60 years) and determined serum concentrations of TMAO, choline and betaine by HPLC-MS/MS. For the CSS, 1,628 community-based adults (40-75 years) completed the blood tests and ultrasonographic NAFLD evaluation. In the CCS, analyses of covariance showed adverse associations of ln-transformed serum levels of TMAO, choline and betaine/choline ratio with the scores of steatosis and total NAFLD activity (NAS) (all P-trend <0.05). The CSS revealed that a greater severity of NAFLD was independently correlated with higher TMAO but lower betaine and betaine/choline ratio (all P-trend <0.05). No significant choline-NAFLD association was observed. Our findings showed adverse associations between the circulating TMAO level and the presence and severity of NAFLD in hospital- and community-based Chinese adults, and a favorable betaine-NAFLD relationship in the community-based participants.

Choline, Its Potential Role in Nonalcoholic Fatty Liver Disease, and the Case for Human and Bacterial Genes

Our understanding of the impact of poor hepatic choline/phosphatidylcholine availability in promoting the steatosis characteristic of human nonalcoholic fatty liver disease (NAFLD) has recently advanced and possibly relates to phosphatidylcholine/phosphatidylethanolamine concentrations in various, membranes as well as cholesterol dysregulation. A role for choline/phosphatidylcholine availability in the progression of NAFLD to liver injury and serious hepatic consequences in some individuals requires further elucidation. There are many reasons for poor choline/phosphatidylcholine availability in the liver, including low intake, estrogen status, and genetic polymorphisms affecting, in particular, the pathway for hepatic de novo phosphatidylcholine synthesis. In addition to free choline, phosphatidylcholine has been identified as a substrate for trimethylamine production by certain intestinal bacteria, thereby reducing host choline bioavailability and providing an additional link to the increased risk of cardiovascular disease faced by those with NAFLD. Thus human choline requirements are highly individualized and biomarkers of choline status derived from metabolomics studies are required to predict those at risk of NAFLD induced by choline deficiency and to provide a basis for human intervention trials.

Immunohistochemical determination of the extracellular matrix modulation in a rat model of choline-deprived myocardium: the effects of carnitine

Choline has been identified as an essential nutrient with crucial role in many vital biological functions. Recent studies have demonstrated that heart dysfunction can develop in the setting of choline deprivation even in the absence of underlying heart disease. Matrix metalloproteinases (MMPs) are responsible for extracellular matrix degradation, and the dysregulation of MMP-2 and MMP-9 has been involved in the pathogenesis of various cardiovascular disorders. The aim of the study was to investigate the role of MMPs and their inhibitors (TIMPs), in the pathogenesis of choline deficiency-induced cardiomyopathy, and the way they are affected by carnitine supplementation. Male Wistar Albino adult rats were divided into four groups and received standard or choline-deficient diet with or without L-carnitine in drinking water (0.15% w/v) for 1 month. Heart tissue immunohistochemistry for MMP-2, MMP-9, TIMP-1, and TIMP-2 was performed. Choline deficiency was associated with suppressed immunohistochemical expression of MMP-2 and an increased expression of TIMP-2 compared to control, while it had no impact on TIMP-1. MMP-9 expression was decreased without, however, reaching statistical significance. Carnitine did not affect MMP-2, MMP-9, TIMP-1 or TIMP-2 expression. The pattern of TIMP and MMP modulation observed in a choline deficiency setting appears to promote fibrosis. Carnitine, although shown to suppress fibrosis, does not seem to affect MMP-2, MMP-9, TIMP-1 or TIMP-2 expression. Further studies will be required to identify the mechanism underlying the beneficial effects of carnitine.

Maternal omega-3 fatty acids and micronutrients modulate fetal lipid metabolism: A review

It is well established that alterations in the mother's diet or metabolism during pregnancy has long-term adverse effects on the lipid metabolism in the offspring. There is growing interest in the role of specific nutrients especially omega-3 fatty acids in the pathophysiology of lipid disorders. A series of studies carried out in humans and rodents in our department have consistently suggested a link between omega-3 fatty acids especially docosahexaenoic acid and micronutrients (vitamin B12 and folic acid) in the one carbon metabolic cycle and its effect on the fatty acid metabolism, hepatic transcription factors and DNA methylation patterns. However the association of maternal intake or metabolism of these nutrients with fetal lipid metabolism is relatively less explored. In this review, we provide insights into the role of maternal omega-3 fatty acids and vitamin B12 and their influence on fetal lipid metabolism through various mechanisms which influence phosphatidylethanolamine-N-methyltransferase activity, peroxisome proliferator activated receptor, adiponectin signaling pathway and epigenetic process like chromatin methylation. This will help understand the possible mechanisms involved in fetal lipid metabolism and may provide important clues for the prevention of lipid disorders in the offspring.

Effects of choline on health across the life course: a systematic review

CONTEXT

Choline is a precursor of both betaine and acetylcholine and might, therefore, influence cardiovascular and cognitive outcomes. There has been concern, however, that it may influence blood lipid levels because it is an essential component of very-low-density lipoproteins.

OBJECTIVE

The aim was to systematically review, using PRISMA guidelines, the literature pertaining to the effects of choline on body composition and on metabolic, cardiovascular, respiratory, and neurological outcomes in different life stages.

DATA SOURCES

The MEDLINE, Embase, Cochrane Central, Web of Science, PubMed, and Google Scholar databases were searched up to July 2014.

DATA EXTRACTION

Fifty relevant articles were identified. These comprised trials and cohort, case-control, and cross-sectional studies that assessed blood levels of choline, dietary intake of choline, and supplementation with choline in a population free of diseases at baseline.

DATA SYNTHESIS

There is some observational evidence that choline during pregnancy may be beneficial for the neurological health of the child. In adults, choline may have beneficial effects on cognition, but high-quality (intervention) studies are lacking. Results on the effects of choline on body composition, blood lipids, and cardiovascular health were inconsistent.

CONCLUSIONS

Evidence to confirm the suggested effects of choline on health in different stages of life is scarce. Potential effects of choline need to be confirmed by intervention studies. Possible harmful effects on cardiometabolic health need careful evaluation.

Choline and Cystine Deficient Diets in Animal Models with Hepatocellular Injury: Evaluation of Oxidative Stress and Expression of RAGE, TNF-α, and IL-1β

This study aims to evaluate the effects of diets deficient in choline and/or cystine on hepatocellular injury in animal models (young male Wistar rats, aged 21 days), by monitoring some of the oxidative stress biomarkers and the expression of RAGE, TNF-α, and IL-1β. The animals were divided into 6 groups (n = 10) and submitted to different diets over 30 days: AIN-93 diet (standard, St), AIN-93 choline deficient (CD) diet and AIN-93 choline and cystine deficient (CCD) diet, in the pellet (pl) and powder (pw) diet forms. Independently of the diet form, AIN-93 diet already led to hepatic steatosis and CD/CCD diets provoked hepatic damage. The increase of lipid peroxidation, represented by the evaluation of thiobarbituric acid reactive species, associated with the decrease of levels of antioxidant enzymes, were the parameters with higher significance toward redox profile in this model of hepatic injury. Regarding inflammation, in relation to TNF-α, higher levels were evidenced in CD_(pl), while, for IL-1β, no significant alteration was detected. RAGE expression was practically the same in all groups, with exception of CCD_(pw) versus CCD_(pl). These results together confirm that AIN-93 causes hepatic steatosis and choline and/or cysteine deficiencies produce important hepatic injury associated with oxidative stress and inflammatory profiles.

Alcoholic Steatosis in Different Strains of Rat: A Comparative Study

Background

Different strains of rats have been used to study alcoholic liver disease (ALD) while the reason for selecting a particular rat strain was not apparent.

Purpose

The aim of our study was to compare outbred (Wistar) and inbred (Fischer) strains to evaluate pathological, biochemical changes, and gene expression differences associated with ethanol-induced early hepatic steatosis.

Study Design

Male Wistar and Fischer-344 rats were pair-fed for 6 weeks with or without 5% ethanol in Lieber-DeCarli liquid diet. Livers were analyzed for histological and lipid-related differences.

Results

Hepatic midzonal steatosis was mainly found in Wistar rats while Fischer rats showed mostly pericentral steatosis. Increased hepatic steatosis in ethanol-fed Wistar rats is supported by increases in lipids with related genes and transcription factors involved in fatty acid and triglyceride synthesis.

Conclusion

Our data showed that Fischer rats are relatively less prone to ethanol-mediated steatosis with pericentral lipid deposition pattern in the liver which is similar to humans and show no trace level of lipid accumulation in pair-fed controls as observed in Wistar (outbred) strain. Therefore, Fischer rats are better suited for lipid studies in an early development of ALD.

Importance of Choline as Essential Nutrient and Its Role in Prevention of Various Toxicities

Choline is a water-soluble essential nutrient included as a member of the vitamin B12 group owing to its structural similarities with that of the other members of the group. Its roles and functions, however, extend much wider than that of the vitamins with which it is grouped. Choline is vital for maintenance of various key metabolic processes which play a role in the prevention or progression of various health impairments. The occurrence of diseases like neural tube defect (NTD) and Alzheimer’s is prevented by the metabolic role of choline. It is also indispensable for mitigation of various forms of toxic contamination. While adequate level of choline in the body is essential, an excess of choline can result in various forms of disorder. To maintain the optimal level of choline in the body can be a challenge. The vital roles played by choline together with the range of contradictions and problems that choline presents make choline an interesting area of study. This paper attempts to summarize and review some recent publications on choline that have opened up new prospect in understanding the multiple role played by choline and in throwing light on the role played by this wonder essential nutrient in mitigating various forms of toxic contamination.