Identification of prognostic and diagnostic biomarkers of glucose intolerance in ApoE3Leiden mice

A Transcriptomic Response to Lactiplantibacillus plantarum-KCC48 against High-Fat Diet-Induced Fatty Liver Diseases in Mice

The most prevalent chronic liver disorder in the world is fatty liver disease caused by a high-fat diet. We examined the effects of Lactiplantibacillus plantarum-KCC48 on high-fat diet-induced (HFD) fatty liver disease in mice. We used the transcriptome tool to perform a systematic evaluation of hepatic mRNA transcripts changes in high-fat diet (HFD)-fed animals and high-fat diet with L. plantarum (HFLPD)-fed animals. HFD causes fatty liver diseases in animals, as evidenced by an increase in TG content in liver tissues compared to control animals. Based on transcriptome data, 145 differentially expressed genes (DEGs) were identified in the liver of HFD-fed mice compared to control mice. Moreover, 61 genes were differentially expressed in the liver of mice fed the HFLPD compared to mice fed the HFD. Additionally, 43 common DEGs were identified between HFD and HFLPD. These genes were enriched in metabolic processes, retinol metabolism, the PPAR signaling pathway, fatty acid degradation, arachidonic metabolism, and steroid hormone synthesis. Taking these data into consideration, it can be concluded that L. plantarum-KCC48 treatment significantly regulates the expression of genes involved in hepatosteatosis caused by HFD, which may prevent fatty liver disease.

Lipid ratios representing SCD1, FADS1, and FADS2 activities as candidate biomarkers of early growth and adiposity

BACKGROUND

Altered lipid metabolism in early life has been associated with subsequent weight gain and predicting this could aid in obesity prevention and risk management. Here, a lipidomic approach was used to identify circulating markers for future obesity risk in translational murine models and validate in a human infant cohort.

METHODS

Lipidomics was performed on the plasma of APOE*3 Leiden, Ldlr-/-.Leiden, and the wild-type C57BL/6J mice to capture candidate biomarkers predicting subsequent obesity parameters after exposure to high-fat diet. The identified candidate biomarkers were mapped onto corresponding lipid metabolism pathways and were investigated in the Cambridge Baby Growth Study. Infants' growth and adiposity were measured at 0-24 months. Capillary dried blood spots were sampled at 3 months for lipid profiling analysis.

FINDINGS

From the mouse models, cholesteryl esters were correlated with subsequent weight gain and other obesity parameters after HFD period (Spearman's r≥0.5, FDR p values <0.05) among APOE*3 Leiden and Ldlr-/-.Leiden mice, but not among the wild-type C57BL/6J. Pathway analysis showed that those identified cholesteryl esters were educts or products of desaturases activities: stearoyl-CoA desaturase-1 (SCD1) and fatty acid desaturase (FADS) 1 and 2. In the human cohort, lipid ratios affected by SCD1 at 3 months was inversely associated with 3-12 months weight gain (B±SE=-0.31±0.14, p=0.027), but positively with 12-24 months weight and adiposity gains (0.17±0.07, p=0.02 and 0.17±0.07, 0.53±0.26, p=0.04, respectively). Lipid ratios affected by SCD1 and FADS2 were inversely associated with adiposity gain but positively with height gain between 3-12 months.

INTERPRETATION

From murine models to human setting, the ratios of circulating lipid species indicating key desaturase activities in lipid metabolism were associated with subsequent body size increase, providing a potential tool to predict early life weight gain.

Acetate Revisited: A Key Biomolecule at the Nexus of Metabolism, Epigenetics, and Oncogenesis - Part 2: Acetate and ACSS2 in Health and Disease

Acetate, the shortest chain fatty acid, has been implicated in providing health benefits whether it is derived from the diet or is generated from microbial fermentation of fiber in the gut. These health benefits range widely from improved cardiac function to enhanced red blood cell generation and memory formation. Understanding how acetate could influence so many disparate biological functions is now an area of intensive research. Protein acetylation is one of the most common post-translational modifications and increased systemic acetate strongly drives protein acetylation. By virtue of acetylation impacting the activity of virtually every class of protein, acetate driven alterations in signaling and gene transcription have been associated with several common human diseases, including cancer. In part 2 of this review, we will focus on some of the roles that acetate plays in health and human disease. The acetate-activating enzyme acyl-CoA short-chain synthetase family member 2 (ACSS2) will be a major part of that focus due to its role in targeted protein acetylation reactions that can regulate central metabolism and stress responses. ACSS2 is the only known enzyme that can recycle acetate derived from deacetylation reactions in the cytoplasm and nucleus of cells, including both protein and metabolite deacetylation reactions. As such, ACSS2 can recycle acetate derived from histone deacetylase reactions as well as protein deacetylation reactions mediated by sirtuins, among many others. Notably, ACSS2 can activate acetate released from acetylated metabolites including N-acetylaspartate (NAA), the most concentrated acetylated metabolite in the human brain. NAA has been associated with the metabolic reprograming of cancer cells, where ACSS2 also plays a role. Here, we discuss the context-specific roles that acetate can play in health and disease.

Vitamin D metabolites influence expression of genes concerning cellular viability and function in insulin producing β-cells (INS1E)

BACKGROUND

Studies have shown that vitamin D can enhance glucose-stimulated insulin secretion (GSIS) and change the expression of genes in pancreatic β-cells. Still the mechanisms linking vitamin D and GSIS are unknown.

MATERIAL AND METHODS

We used an established β-cell line, INS1E. INS1E cells were pre-treated with 10 nM 1,25(OH)₂vitamin D or 10 nM 25(OH)vitamin D for 72 h and stimulated with 22 mM glucose for 60 min. RNA was extracted for gene expression analysis.

RESULTS

Expression of genes affecting viability, apoptosis and GSIS changed after pre-treatment with both 1,25(OH)₂vitamin D and 25(OH)vitamin D in INS1E cells. Stimulation with glucose after pre-treatment of INS1E cells with 1,25(OH)₂vitamin D resulted in 181 differentially expressed genes, whereas 526 genes were differentially expressed after pre-treatment with 25(OH)vitamin D.

CONCLUSION

Vitamin D metabolites may affect pancreatic β-cells and GSIS through changed gene expression for genes involved in β-cell function and viability.

Food intake regulation by leptin: Mechanisms mediating gluconeogenesis and energy expenditure

Regulation of blood glucose levels and body fat is critical for survival. Leptin circulates freely in blood and controls body weight and food intake mainly through hypothalamic receptors and regulates glucose metabolism in the liver both directly through leptin receptors and indirectly via the hypothalamic receptors of central nervous system. Leptin affects food intake regulation and eventually glucose metabolism, lipometabolism, endocrine and immune functions, reproductive function, adipose tissue metabolism and energy expenditure. Leptin also exerts peripheral effects directly on glucose metabolism and gluconeogenesis. Most of obese human subjects have elevated plasma levels of leptin associated to the size of their total adipose tissue mass. Hence gluconeogenic function may be an essential factor in the regulation of nutritional intake and weight gain. The aim of this review is therefore to identify and module the possible effects of leptin with special application in gluconeogenesis. In addition, this review includes the study of fat consumption and energy expenditure in the body. Specific modulation of leptin receptors and adipose tissues functioning could have important inference on therapeutic strategies.

Roles of cancer/testis antigens (CTAs) in breast cancer

Breast cancer is the most common cancer diagnosed and is the second leading cause of cancer death among women in the US. For breast cancer, early diagnosis and efficient therapy remains a significant clinical challenge. Therefore, it is necessary to identify novel tumor associated molecules to target for biomarker development and immunotherapy. In this regard, cancer testis antigens (CTAs) have emerged as a potential clinical biomarker targeting immunotherapy for various malignancies due to the nature of its characteristics. CTAs are a group of tumor associated antigens (TAAs) that display normal expression in immune-privileged organs, but display aberrant expression in several types of cancers, particularly in advanced cancers. Investigation of CTAs for the clinical management of breast malignancies indicates that these TAAs have potential roles as novel biomarkers, with increased specificity and sensitivity compared to those currently used in the clinic. Moreover, TAAs could be therapeutic targets for cancer immunotherapy. This review is an attempt to address the promising CTAs in breast cancer and their possible clinical implications as biomarkers and immunotherapeutic targets with particular focus on challenges and future interventions.

Identification of a nutrient-sensing transcriptional network in monocytes by using inbred rat models on a cafeteria diet

Obesity has reached pandemic levels worldwide. The current models of diet-induced obesity in rodents use predominantly high-fat based diets that do not take into account the consumption of variety of highly palatable, energy-dense foods that are prevalent in Western society. We and others have shown that the cafeteria (CAF) diet is a robust and reproducible model of human metabolic syndrome with tissue inflammation in the rat. We have previously shown that inbred rat strains such as Wistar Kyoto (WKY) and Lewis (LEW) show different susceptibilities to CAF diets with distinct metabolic and morphometric profiles. Here, we show a difference in plasma MCP-1 levels and investigate the effect of the CAF diet on peripheral blood monocyte transcriptome, as powerful stress-sensing immune cells, in WKY and LEW rats. We found that 75.5% of the differentially expressed transcripts under the CAF diet were upregulated in WKY rats and were functionally related to the activation of the immune response. Using a gene co-expression network constructed from the genes differentially expressed between CAF diet-fed LEW and WKY rats, we identified acyl-CoA synthetase short-chain family member 2 (Acss2) as a hub gene for a nutrient-sensing cluster of transcripts in monocytes. The Acss2 genomic region is significantly enriched for previously established metabolism quantitative trait loci in the rat. Notably, monocyte expression levels of Acss2 significantly correlated with plasma glucose, triglyceride, leptin and non-esterified fatty acid (NEFA) levels as well as morphometric measurements such as body weight and the total fat following feeding with the CAF diet in the rat. These results show the importance of the genetic background in nutritional genomics and identify inbred rat strains as potential models for CAF-diet-induced obesity.

Summary: Feeding with a cafeteria diet (CAF) is a reproducible model of human metabolic syndrome in the rat. By using inbred rat models of nutrigenomics, we have studied the effect of CAF on monocyte transcriptome.

Recent advances in lipidomics for disease research

Lipidomics is an important branch of metabolomics, which aims at the detailed analysis of lipid species and their multiple roles in the living system. In recent years, the development of various analytical methods for effective identification and characterization of lipids has greatly promoted the process of lipidomics. Meanwhile, as many diseases demonstrate a remarkable alteration in lipid profiles compared with that of healthy people, lipidomics has been extensively introduced to disease research. The comprehensive lipid profiling provides a chance to discover novel biomarkers for specific disease. In addition, it plays a crucial role in the study of lipid metabolism, which could illuminate the pathogenesis of diseases. In this review, after brief discussion of analytical methods for lipidomics in clinical research, we focus on the recent advances of lipidomics related to four types of diseases, including cancer, atherosclerosis, diabetes mellitus, and Alzheimer's disease.

Transcriptional profiles of peripheral blood leukocytes identify patients with cholangiocarcinoma and predict outcome

Cholangiocarcinoma (CCA), a slow growing but highly metastatic tumor, is highly prevalent in Northeast Thailand. Specific tests that predict prognosis of CCA remain elusive. The present study was designed to investigate whether peripheral blood leukocyte (PBL) transcriptional profiles might be of use as a prognostic test in CCA patients. Gene expression profiles of PBLs from 9 CCA and 8 healthy subjects were conducted using the Affymetrix HG_U133 Plus 2.0 GeneChip. We indentified informative PBLs gene expression profiles that could reliably distinguish CCA patients from healthy subjects. Of these CCA specific genes, 117 genes were up regulated and 60 were down regulated. The molecular and cellular functions predicted for these CCA specific genes according to the Gene Ontology database indicated differential PBL expression of host immune response and tumor progression genes (EREG, TGF β1, CXCL2, CXCL3, IL-8, and VEGFA). The expression levels of 9 differentially expressed genes were verified in 36 CCA vs 20 healthy subjects. A set of three tumor invasion related genes (PLAU, CTSL and SERPINB2) computed as "prognostic index" was found to be an independent and statistically significant predictor for CCA patient survival. The present study shows that CCA PBLs may serve as disease predictive clinically accessible surrogates for indentifying expressed genes reflective of CCA disease severity.

Cross-species comparison of genes related to nutrient sensing mechanisms expressed along the intestine

INTRODUCTION

Intestinal chemosensory receptors and transporters are able to detect food-derived molecules and are involved in the modulation of gut hormone release. Gut hormones play an important role in the regulation of food intake and the control of gastrointestinal functioning. This mechanism is often referred to as "nutrient sensing". Knowledge of the distribution of chemosensors along the intestinal tract is important to gain insight in nutrient detection and sensing, both pivotal processes for the regulation of food intake. However, most knowledge is derived from rodents, whereas studies in man and pig are limited, and cross-species comparisons are lacking.

AIM

To characterize and compare intestinal expression patterns of genes related to nutrient sensing in mice, pigs and humans.

METHODS

Mucosal biopsy samples taken at six locations in human intestine (n = 40) were analyzed by qPCR. Intestinal scrapings from 14 locations in pigs (n = 6) and from 10 locations in mice (n = 4) were analyzed by qPCR and microarray, respectively. The gene expression of glucagon, cholecystokinin, peptide YY, glucagon-like peptide-1 receptor, taste receptor T1R3, sodium/glucose cotransporter, peptide transporter-1, GPR120, taste receptor T1R1, GPR119 and GPR93 was investigated. Partial least squares (PLS) modeling was used to compare the intestinal expression pattern between the three species.

RESULTS AND CONCLUSION

The studied genes were found to display specific expression patterns along the intestinal tract. PLS analysis showed a high similarity between human, pig and mouse in the expression of genes related to nutrient sensing in the distal ileum, and between human and pig in the colon. The gene expression pattern was most deviating between the species in the proximal intestine. Our results give new insights in interspecies similarities and provide new leads for translational research and models aiming to modulate food intake processes in man.

Plasma lipidome is independently associated with variability in metabolic syndrome in Mexican American families

Plasma lipidome is now increasingly recognized as a potentially important marker of chronic diseases, but the exact extent of its contribution to the interindividual phenotypic variability in family studies is unknown. Here, we used the rich data from the ongoing San Antonio Family Heart Study (SAFHS) and developed a novel statistical approach to quantify the independent and additive value of the plasma lipidome in explaining metabolic syndrome (MS) variability in Mexican American families recruited in the SAFHS. Our analytical approach included two preprocessing steps: principal components analysis of the high-resolution plasma lipidomics data and construction of a subject-subject lipidomic similarity matrix. We then used the Sequential Oligogenic Linkage Analysis Routines software to model the complex family relationships, lipidomic similarities, and other important covariates in a variance components framework. Our results suggested that even after accounting for the shared genetic influences, indicators of lipemic status (total serum cholesterol, TGs, and HDL cholesterol), and obesity, the plasma lipidome independently explained 22% of variability in the homeostatic model of assessment-insulin resistance trait and 16% to 22% variability in glucose, insulin, and waist circumference. Our results demonstrate that plasma lipidomic studies can additively contribute to an understanding of the interindividual variability in MS.

Looking back into the future: 30 years of metabolomics at TNO

Metabolites have played an essential role in our understanding of life, health, and disease for thousands of years. This domain became much more important after the concept of metabolism was discovered. In the 1950s, mass spectrometry was coupled to chromatography and made the technique more application-oriented and allowed the development of new profiling technologies. Since 1980, TNO has performed system-based metabolic profiling of body fluids, and combined with pattern recognition has led to many discoveries and contributed to the field known as metabolomics and systems biology. This review describes the development of related concepts and applications at TNO in the biomedical, pharmaceutical, nutritional, and microbiological fields, and provides an outlook for the future.

The hepatic phosphatidylcholine transporter ABCB4 as modulator of glucose homeostasis

The hepatic phosphatidylcholine (PC) transporter ATP-binding cassette (ABC) B4 flops PC from hepatocytes into bile, and its dysfunction causes chronic cholestasis and fibrosis. Because a nuclear receptor-dependent PC pathway has been determined to exert antidiabetic effects, we now analyzed the role of ABCB4 in glucose metabolism. We bred congenic Abcb4-knockout (Abcb4(-/-)) mice on the fibrosis-susceptible BALB/cJ background. Knockout mice and wild-type controls were phenotyped by measuring plasma glucose concentrations, intraperitoneal glucose tolerance, hepatic RNA expression profiles, and liver histology. In addition, 4 procholestatic ABCB4 gene variants were correlated with blood glucose levels in 682 individuals from 2 independent European cohorts. Systemic glucose levels differ significantly between Abcb4(-/-) mice and wild-type controls, and knockout mice display improved glucose tolerance with significantly lower area under the curve values on intraperitoneal glucose challenge. Of note, hepatic expression of the antidiabetic nuclear receptor 5A2 (LRH-1) is induced consistently in Abcb4(-/-) mice, and its specific rare PC ligands are detected in liver by mass spectrometry imaging. In humans, serum glucose levels are associated significantly with the common ABCB4 variant c.711A>T. In summary, ABCB4 might play a critical role in glucose homeostasis in mice and humans. We speculate that the effects could be mediated via LRH-1-dependent PC pathways.