Co-Administration of Soluble Fibres and Lactobacillus casei NCDC19 Fermented Milk Prevents Adiposity and Insulin Resistance Via Modulation of Lipid Mobilization Genes in Diet-Induced Obese Mice.

BACKGROUND: Numerous reports explaining the beneficial health effects of soluble fibres and probiotics on lifestyle disorders have been published. However, a little information is available on coadministration of soluble fibres such as gum acacia & inulin and probiotic lactobacilli. Therefore, in the present study, we have evaluated the synergistic effects of soluble fibres and probiotic fermented milk on adiposity, insulin resistance and dyslipidemia in C57BL/6 mice fed high-fat and sucrose diet for 18 weeks. OBJECTIVE: To explore the synergistic effect of soluble fibres (gum acacia/inulin) and Lactobacillus casei NCDC19 fermented milk on adiposity, insulin resistance and lipid mobilization genes in dietinduced obese mice. METHODS: C57BL/6 mice were divided randomly into three groups (n = 9/group) according to their body weights. The HFS group was fed high-fat and sucrose diet, the HFS-GFM group was fed HFS diet incorporated with gum acacia (7%, w/w) along with L. casei NCDC19 fermented milk and HFSIFM group was fed HFS diet incorporated with inulin (7%, w/w) along with L. casei NCDC19 fermented milk. RESULTS: At the end of the experiment, final body weight, epididymal fat (E.fat) weight, and adipocyte size were found to be lower in groups received either gum acacia or inulin in combination with L. casei NCDC19 fermented milk (HFS-GFM or HFS-IFM). Also, fasting blood glucose, serum insulin, triglycerides, and VLDL-cholesterol levels were decreased significantly in both HFS-GFM and HFSIFM fed groups. Furthermore, relative mRNA expression of genes (cpt1, foxa2, pgc1ß, and pparα) related to fatty acid oxidation enhanced significantly in the liver. In E.fat pad, expression of adiponectin was upregulated, whereas, leptin expression was reduced considerably. Also, expression of fasting-induced adipose factor enhanced significantly in the distal ileum of mice in HFS-GFM and HFS-IFM groups. CONCLUSION: Overall, we demonstrate that co-administration of soluble fibres viz. gum acacia, inulin and L. casei NCDC19 fermented milk exhibited the anti-adiposity effects, improved insulin sensitivity and dyslipidemia in mice via modulation of lipid mobilization genes.

TMEM41B is a novel regulator of autophagy and lipid mobilization.

Autophagy maintains cellular homeostasis by targeting damaged organelles, pathogens, or misfolded protein aggregates for lysosomal degradation. The autophagic process is initiated by the formation of autophagosomes, which can selectively enclose cargo via autophagy cargo receptors. A machinery of well-characterized autophagy-related proteins orchestrates the biogenesis of autophagosomes; however, the origin of the required membranes is incompletely understood. Here, we have applied sensitized pooled CRISPR screens and identify the uncharacterized transmembrane protein TMEM41B as a novel regulator of autophagy. In the absence of TMEM41B, autophagosome biogenesis is stalled, LC3 accumulates at WIPI2- and DFCP1-positive isolation membranes, and lysosomal flux of autophagy cargo receptors and intracellular bacteria is impaired. In addition to defective autophagy, TMEM41B knockout cells display significantly enlarged lipid droplets and reduced mobilization and ß-oxidation of fatty acids. Immunostaining and interaction proteomics data suggest that TMEM41B localizes to the endoplasmic reticulum (ER). Taken together, we propose that TMEM41B is a novel ER-localized regulator of autophagosome biogenesis and lipid mobilization.

Adipocyte STAT5 deficiency promotes adiposity and impairs lipid mobilisation in mice.

AIMS/HYPOTHESIS: Dysfunction of lipid metabolism in white adipose tissue can substantially interfere with health and quality of life, for example in obesity and associated metabolic diseases. Therefore, it is important to characterise pathways that regulate lipid handling in adipocytes and determine how they affect metabolic homeostasis. Components of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway are involved in adipocyte physiology and pathophysiology. However, the exact physiological importance of the STAT family member STAT5 in white adipose tissue is yet to be determined. Here, we aimed to delineate adipocyte STAT5 functions in the context of lipid metabolism in white adipose tissue. METHODS: We generated an adipocyte specific knockout of Stat5 in mice using the Adipoq-Cre recombinase transgene followed by in vivo and in vitro biochemical and molecular studies. RESULTS: Adipocyte-specific deletion of Stat5 resulted in increased adiposity, while insulin resistance and gluconeogenic capacity was decreased, indicating that glucose metabolism can be improved by interfering with adipose STAT5 function. Basal lipolysis and fasting-induced lipid mobilisation were diminished upon STAT5 deficiency, which coincided with reduced levels of the rate-limiting lipase of triacylglycerol hydrolysis, adipose triglyceride lipase (ATGL, encoded by Pnpla2) and its coactivator comparative gene identification 58 (CGI-58). In a mechanistic analysis, we identified a functional STAT5 response element within the Pnpla2 promoter, indicating that Pnpla2 is transcriptionally regulated by STAT5. CONCLUSIONS/INTERPRETATION: Our findings reveal an essential role for STAT5 in maintaining lipid homeostasis in white adipose tissue and provide a rationale for future studies into the potential of STAT5 manipulation to improve outcomes in metabolic diseases.

Protein kinase STK25 controls lipid partitioning in hepatocytes and correlates with liver fat content in humans.

AIMS/HYPOTHESIS: Type 2 diabetes is closely associated with pathological lipid accumulation in the liver, which is suggested to actively contribute to the development of insulin resistance. We recently identified serine/threonine protein kinase 25 (STK25) as a regulator of liver steatosis, whole-body glucose tolerance and insulin sensitivity in a mouse model system. The aim of this study was to assess the role of STK25 in the control of lipid metabolism in human liver. METHODS: Intracellular fat deposition, lipid metabolism and insulin sensitivity were studied in immortalised human hepatocytes (IHHs) and HepG2 hepatocellular carcinoma cells in which STK25 was overexpressed or knocked down by small interfering RNA. The association between STK25 mRNA expression in human liver biopsies and hepatic fat content was analysed. RESULTS: Overexpression of STK25 in IHH and HepG2 cells enhanced lipid deposition by suppressing ß-oxidation and triacylglycerol (TAG) secretion, while increasing lipid synthesis. Conversely, knockdown of STK25 attenuated lipid accumulation by stimulating ß-oxidation and TAG secretion, while inhibiting lipid synthesis. Furthermore, TAG hydrolase activity was repressed in hepatocytes overexpressing STK25 and reciprocally increased in cells with STK25 knockdown. Insulin sensitivity was reduced in STK25-overexpressing cells and enhanced in STK25-deficient hepatocytes. We also found a statistically significant positive correlation between STK25 mRNA expression in human liver biopsies and hepatic fat content. CONCLUSIONS/INTERPRETATION: Our data suggest that STK25 regulates lipid partitioning in human liver cells by controlling TAG synthesis as well as lipolytic activity and thereby NEFA release from lipid droplets for ß-oxidation and TAG secretion. Our findings highlight STK25 as a potential drug target for the prevention and treatment of type 2 diabetes.

Cinética lipídica en el tratamiento antiviral dual en pacientes con hepatitis crónica C / Lipid kinetics during dual antiviral therapy in patients with chronic hepatitis C

Fundamento y objetivo: Valorar el metabolismo basal y cinético de las lipoproteínas durante el primer mes de biterapia en pacientes con hepatitis crónica C genotipo 1 (HCC-1). Pacientes y métodos: Estudio longitudinal, prospectivo, que incluyó 99 pacientes HCC-1 naive, biopsiados y tratados con biterapia. Clasificamos a nuestros pacientes en 5 niveles de exigencia lipídica, según el grado de fibrosis hepática, carga viral basal y ratio de infectividad (cociente entre concentraciones medias de triglicéridos y colesterol unido a lipoproteínas de alta densidad durante el primer mes), estableciendo para cada uno de ellos, durante este período, una concentración media mínima necesaria de colesterol unido a lipoproteínas de baja densidad (colesterol LDL) para que el paciente alcanzara un «metabolismo lipídico favorable» (MLF), y valoramos su relación con las tasas de curación. Resultados: Alcanzaron mayores tasas de curación aquellos pacientes con fibrosis F3-F4 que presentaron mayores concentraciones basales de colesterol LDL, así como aquellos que consiguieron mantener durante el primer mes de biterapia una ratio de infectividad menor de 3,2 y mayores concentraciones medias de colesterol LDL: media (DE) de 100 (23) mg/dl en «curados» frente a 89 (28) mg/dl en «no curados»,odds ratio 1,1, intervalo de confianza del 95% (1,0-1,2) (p < 0,05), siendo más significativas estas diferencias en los genotipos IL-28B-CC (p = 0,013). Aquellos que alcanzaron la respuesta virológica sostenida presentaron mayores tasas de MLF. Conclusiones: No todos los pacientes con HCC-1 van a presentar durante el primer mes de tratamiento una cinética lipídica favorable, siendo necesario para curarse y/o alcanzar un MLF mantener durante este período unas concentraciones plasmáticas medias de colesterol LDL mayores. Aquellos con ausencia de un MLF podrían beneficiarse del uso de estatinas (AU)

Background and objective: We analyzed baseline and kinetic characteristics of lipid metabolism during the first month of bitherapy in patients with chronic hepatitis C genotype 1 (CHC-1). Patients and methods: A longitudinal, prospective study including 99 naïve CHC-1 patients with liver biopsy who were treated with bitherapy. Our patients were assigned to one of 5 different “degrees of lipid requirement” that we established depending on the degree of liver fibrosis, baseline viral load and infectivity ratio (ratio between the median level of triglycerides and high densitity lipoproteins-cholesterol during the first month). The goal was to achieve 'a favorable lipid metabolism' (FLM) by establishing a necessary minimum level of low density lipoproteins (LDL)-cholesterol during this period for each one of them. We also analyzed the relationship with the rate of sustained virological response. Results: Patients with liver fibrosis F3-F4 who had higher baseline levels of LDL-cholesterol achieved higher rates of sustained virological response. Those patients who had a lower value of infectivity ratio and median levels of LDL-cholesterol during the first month of bitherapy also achieved higher rates of sustained virological response: SVR group 100 (23) mg/dl against non-SVR group: 89 (28) mg/dl; odds ratio 1.1; 95% confidence interval (1.0-1.2); P < .05, these differences being more significant for genotype IL-28B-CC (P = .013). Patients with sustained virological response had higher rates of FLM. Conclusions: Not every patient with CHC-1 has the same lipid kinetics during the first month of bitherapy, and it is necessary to achieve a sustained virological response and/or a FLM to keep higher plasma levels of LDL-cholesterol during this period. Those subjects without FLM could benefit from statins (AU)

Lipid presentation by human CD1 molecules and the diverse T cell populations that respond to them.

CD1 molecules bind and present lipid-based antigens to T cells. Humans express both Group 1 (CD1a, CD1b and CD1c) and Group 2 (CD1d) CD1 molecules with nonredundant functions in the human immune response. Studies of Group 1 CD1 molecules and the T cells that respond to them have lagged behind Group 2 due to the lack of a suitable model system. However, recent work has thrust the Group 1 CD1s into the limelight, revealing their importance in tissue surveillance and microbial defense. Here I review recent advances in Group 1 CD1 lipid presentation, the T cell populations that respond to them and the role of CD1 molecules in engagement of human γδ T cells.

Time-dependent changes in lipid metabolism in mice with methionine choline deficiency-induced fatty liver disease.

Methionine and choline-deficient diet (MCD)-induced fatty liver is one of the best-studied animal models of fatty liver disease. The present study was performed to clarify the relative contributions of individual lipid metabolic pathways to the pathogenesis of MCD-induced fatty liver. Hepatic lipogenesis mediated by the sterol regulatory element-binding protein (SREBP-1c) was increased at 1 week, but not at 6 weeks, of MCD feeding. On the other hand, (14)C-palmitate oxidation did not change at 1 week, but significantly decreased at 6 weeks. This decrease was associated with increased expression of fatty acid translocase, a key enzyme involved in fatty acid uptake. Expression of endoplasmic reticulum stress markers was increased in mice given MCD for both 1 and 6 weeks. These findings suggest the presence of time-dependent differences in lipid metabolism in MCD-induced fatty liver disease: SREBP-1c-mediated lipogenesis is important in the early stages of fatty liver disease, whereas increased fatty acid uptake and decreased fatty acid oxidation become more important in the later stages.

The central type Y amphipathic alpha-helices of apolipoprotein AI are involved in the mobilization of intracellular cholesterol depots.

We studied the role of a central domain of human apolipoprotein AI (apoAI) in cholesterol mobilization and removal from cells. In order to check different protein conformations, we tested different sized and cholesterol-content reconstituted apoAI particles (rHDL). Meanwhile cholesterol-free discs were active to induce mobilization, only small cholesterol-containing rHDL were active. To test the influence of a central domain in such events, we used two apoAI variants: one, with its central Y helix pair replaced by the C-terminal domain, and the other having a lysine deleted in central region. The helix-swapping variant decrease the cholesterol pool available to acyl-CoA cholesterol acyl transferase and increase mobilization of newly synthesized cholesterol. Instead, the deletion mutant had no effect on both events. We conclude that the central domain of apoAI is involved in cholesterol cell traffic and solubilization, and that a Y-type charge distribution in polar face may be required, as well as a correct helices-polar face orientation.

Uncoupling protein-2 modulates the lipid metabolic response to fasting in mice.

Uncoupling protein-2 (UCP2) regulates insulin secretion by controlling ATP levels in beta-cells. Although UCP2 deficiency improves glycemic control in mice, increased expression of UCP2 interferes with glucose-stimulated insulin secretion. These observations link UCP2 to beta-cell dysfunction in type 2 diabetes with a perplexing evolutionary role. We found higher residual serum insulin levels and blunted lipid metabolic responses in fasted ucp2(-/-) mice, supporting the concept that UCP2 evolved to suppress insulin effects and to accommodate the fuel switch to fatty acids during starvation. In the absence of UCP2, fasting initially promotes peripheral lipolysis and hepatic fat accumulation at less than expected rates but culminates in protracted steatosis, indicating diminished hepatic utilization and clearance of fatty acids. We conclude that UCP2-mediated control of insulin secretion is a physiologically relevant mechanism of the metabolic response to fasting.

[ABCA-transporters: regulators of cellular lipid transport]. / ABCA-transportører - regulatorer av den cellulaere lipidtransporten.

BACKGROUND: The transport of lipids, which is orchestrated by a multitude of molecular factors, is a key feature of the physiology of living cells. A new group of transporter protein, the A-subclass of ATP-binding cassette (ABC) transporters, was recently discovered. ABCA-transporters play pivotal roles in cellular lipid transport and their discovery has brought important new insights into the molecular basis of this process. This review article presents the biology of ABCA-transport proteins and their implication for clinical medicine. MATERIAL AND METHODS: Literature retrieved from Pubmed, including own research results, formed the basis for the article. RESULTS AND INTERPRETATION: Mutations in ABCA-transporter genes have been shown to result in hereditary diseases involving major physiologicical processes in the cardiovascular, respiratory, visual and integumentary systems. Accumulated evidence suggests that ABCA-transporters play critical roles in the pathogenesis of complex multifactorial disorders with a high incidence; such as atherosclerosis, age-related macula degeneration and Alzheimer's disease.

Differential gene expression between visceral and subcutaneous fat depots.

Abdominal obesity has been linked to the development of insulin resistance and Type 2 diabetes mellitus (DM2). By surgical removal of visceral fat (VF) in a variety of rodent models, we prevented insulin resistance and glucose intolerance, establishing a cause-effect relationship between VF and the metabolic syndrome. To characterize the biological differences between visceral and peripheral fat depots, we obtained perirenal visceral (VF) and subcutaneous (SC) fat from 5 young rats. We extracted mRNA from the fat tissue and performed gene array hybridization using Affymetrix technology with a platform containing 9 000 genes. Out of the 1 660 genes that were expressed in fat tissue, 297 (17.9 %) genes show a two-fold or higher difference in their expression between the two tissues. We present the 20 genes whose expression is higher in VF fat (by 3 - 7 fold) and the 20 genes whose expression is higher in SC fat (by 3 - 150 fold), many of which are predominantly involved in glucose homeostasis, insulin action, and lipid metabolism. We confirmed the findings of gene array expression and quantified the changes in expression in VF of genes involved in insulin resistance (PPARgamma leptin) and its syndrome (angiotensinogen and plasminogen activating inhibitor-1, PAI-1) by real-time PCR (qRT-PCR) technology. Finally, we demonstrated increased expression of resistin in VF by around 12-fold and adiponectin by around 4-fold, peptides that were not part of the gene expression platform. These results indicate that visceral fat and subcutaneous fat are biologically distinct.