51
|
Nobili V, Bedogni G, Berni Canani R, Brambilla P, Cianfarani S, Pietrobelli A, Agostoni C. The potential role of fatty liver in paediatric metabolic syndrome: a distinct phenotype with high metabolic risk? Pediatr Obes 2012; 7:e75-80. [PMID: 23001964 DOI: 10.1111/j.2047-6310.2012.00089.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 06/14/2012] [Accepted: 07/17/2012] [Indexed: 12/14/2022]
Abstract
BACKGROUND The prevalence of obesity and its metabolic consequences has dramatically increased in the last two decades urging physicians to find a reliable definition for early detection, treatment and possibly prevention of metabolic syndrome (MS). MS could be diagnosed in adult patients in the presence of a large waist circumference and ≥2 of the following features: high serum triglycerides, low serum high-density lipoprotein cholesterol, high blood pressure and high fasting glucose. The definition of MS in children is more problematic, and the potential role of its single components on metabolic risk remains largely undefined. Recent evidence strongly suggests not only a relationship between non-alcoholic fatty liver disease (NAFLD) and MS in obese children, adolescents and adults, but also the key role exerted by liver fat deposition in the pathogenesis of MS. CONCLUSION We propose that NAFLD should be routinely checked in obese subjects because early lifestyle changes may be effective in reducing the overall risk of MS.
Collapse
Affiliation(s)
- V Nobili
- Metabolic and Autoimmune Liver Disease Unit, Bambino Gesù Children's Hospital, Rome, Italy.
| | | | | | | | | | | | | |
Collapse
|
52
|
Intestinal GATA4 deficiency protects from diet-induced hepatic steatosis. J Hepatol 2012; 57:1061-8. [PMID: 22750465 PMCID: PMC3477492 DOI: 10.1016/j.jhep.2012.06.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 06/04/2012] [Accepted: 06/22/2012] [Indexed: 01/07/2023]
Abstract
BACKGROUND & AIMS GATA4, a zinc finger domain transcription factor, is critical for jejunal identity. Mice with an intestine-specific GATA4 deficiency (GATA4iKO) are resistant to diet-induced obesity and insulin resistance. Although they have decreased intestinal lipid absorption, hepatic de novo lipogenesis is inhibited. Here, we investigated dietary lipid-dependent and independent effects on the development of steatosis and fibrosis in GATA4iKO mice. METHODS GATA4iKO and control mice were fed a Western-type diet (WTD) or a methionine and choline-deficient diet (MCDD) for 20 and 3 weeks, respectively. Functional effects of GATA4iKO on diet-induced liver steatosis were investigated. RESULTS WTD-but not MCDD-fed GATA4iKO mice showed lower hepatic concentrations of triglycerides, free fatty acids, and thiobarbituric acid reactive species and had reduced expression of lipogenic as well as fibrotic genes compared with controls. Reduced nuclear sterol regulatory element-binding protein-1c protein levels were accompanied by lower lipogenic gene expression. Oil red O and Sirius Red staining of liver sections confirmed the observed reduction in hepatic lipid accumulation and fibrosis. Immunohistochemical staining revealed an increased number of jejunal glucagon-like peptide 1 (GLP-1) positive cells in GATA4iKO mice. Consequently, we found enhanced phosphorylation of hepatic AMP-activated protein kinase and acetyl-CoA carboxylase alpha. CONCLUSIONS Our results provide strong indications for a protective effect of intestinal GATA4 deficiency on the development of hepatic steatosis and fibrosis via GLP-1, thereby blocking hepatic de novo lipogenesis.
Collapse
Key Words
- dnl, de novo lipogenesis
- tg, triglycerides
- nafld, non-alcoholic fatty liver disease
- wtd, western-type diet
- acc, acetyl-coa carboxylase alpha
- mcdd, methionine and choline-deficient diet
- glp-1, glucagon-like peptide-1
- iis, ileal interposition surgery
- gata4iko, intestine-specific gata4 deficiency
- alt, alanine aminotransferase
- ast, aspartate transaminase
- ldh, lactate dehydrogenase
- ffa, free fatty acids
- tbars, thiobarbituric acid reactive substances
- ampk, amp-activated protein kinase
- p, phosphorylated
- p38, p38 mitogen-activated protein kinase
- pparg, peroxisome proliferator-activated receptor gamma
- α-sma, alpha-smooth muscle actin
- srebp-1c, sterol regulatory element-binding protein-1c
- hsc, hepatic stellate cells
- gata4
- non-alcoholic fatty liver disease
- glp-1
- ileal interposition surgery
- de novo lipogenesis
Collapse
|
53
|
Bril F, Lomonaco R, Cusi K. The challenge of managing dyslipidemia in patients with nonalcoholic fatty liver disease. ACTA ACUST UNITED AC 2012. [DOI: 10.2217/clp.12.47] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
54
|
Huang JV, Greyson CR, Schwartz GG. PPAR-γ as a therapeutic target in cardiovascular disease: evidence and uncertainty. J Lipid Res 2012; 53:1738-54. [PMID: 22685322 DOI: 10.1194/jlr.r024505] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Peroxisome proliferator-activated receptor γ (PPAR-γ) is a key regulator of fatty acid metabolism, promoting its storage in adipose tissue and reducing circulating concentrations of free fatty acids. Activation of PPAR-γ has favorable effects on measures of adipocyte function, insulin sensitivity, lipoprotein metabolism, and vascular structure and function. Despite these effects, clinical trials of thiazolidinedione PPAR-γ activators have not provided conclusive evidence that they reduce cardiovascular morbidity and mortality. The apparent disparity between effects on laboratory measurements and clinical outcomes may be related to limitations of clinical trials, adverse effects of PPAR-γ activation, or off-target effects of thiazolidinedione agents. This review addresses these issues from a clinician's perspective and highlights several ongoing clinical trials that may help to clarify the therapeutic role of PPAR-γ activators in cardiovascular disease.
Collapse
Affiliation(s)
- Janice V Huang
- Cardiology Section, Denver VA Medical Center, US Department of Veterans Affairs, Denver, CO, USA
| | | | | |
Collapse
|
55
|
Wang JC, Gray NE, Kuo T, Harris CA. Regulation of triglyceride metabolism by glucocorticoid receptor. Cell Biosci 2012; 2:19. [PMID: 22640645 PMCID: PMC3419133 DOI: 10.1186/2045-3701-2-19] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 05/28/2012] [Indexed: 12/11/2022] Open
Abstract
Glucocorticoids are steroid hormones that play critical and complex roles in the regulation of triglyceride (TG) homeostasis. Depending on physiological states, glucocorticoids can modulate both TG synthesis and hydrolysis. More intriguingly, glucocorticoids can concurrently affect these two processes in adipocytes. The metabolic effects of glucocorticoids are conferred by intracellular glucocorticoid receptors (GR). GR is a transcription factor that, upon binding to glucocorticoids, regulates the transcriptional rate of specific genes. These GR primary target genes further initiate the physiological and pathological responses of glucocorticoids. In this article, we overview glucocorticoid-regulated genes, especially those potential GR primary target genes, involved in glucocorticoid-regulated TG metabolism. We also discuss transcriptional regulators that could act with GR to participate in these processes. This knowledge is not only important for the fundamental understanding of steroid hormone actions, but also are essential for future therapeutic interventions against metabolic diseases associated with aberrant glucocorticoid signaling, such as insulin resistance, dyslipidemia, central obesity and hepatic steatosis.
Collapse
Affiliation(s)
- Jen-Chywan Wang
- Department of Nutritional Science & Toxicology, University of California at Berkeley, Berkeley, CA, 94720, USA.
| | | | | | | |
Collapse
|
56
|
Patterson E, Wall R, Fitzgerald GF, Ross RP, Stanton C. Health implications of high dietary omega-6 polyunsaturated Fatty acids. J Nutr Metab 2012; 2012:539426. [PMID: 22570770 PMCID: PMC3335257 DOI: 10.1155/2012/539426] [Citation(s) in RCA: 493] [Impact Index Per Article: 41.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 11/17/2011] [Accepted: 11/20/2011] [Indexed: 12/17/2022] Open
Abstract
Omega-6 (n-6) polyunsaturated fatty acids (PUFA) (e.g., arachidonic acid (AA)) and omega-3 (n-3) PUFA (e.g., eicosapentaenoic acid (EPA)) are precursors to potent lipid mediator signalling molecules, termed "eicosanoids," which have important roles in the regulation of inflammation. In general, eicosanoids derived from n-6 PUFA are proinflammatory while eicosanoids derived from n-3 PUFA are anti-inflammatory. Dietary changes over the past few decades in the intake of n-6 and n-3 PUFA show striking increases in the (n-6) to (n-3) ratio (~15 : 1), which are associated with greater metabolism of the n-6 PUFA compared with n-3 PUFA. Coinciding with this increase in the ratio of (n-6) : (n-3) PUFA are increases in chronic inflammatory diseases such as nonalcoholic fatty liver disease (NAFLD), cardiovascular disease, obesity, inflammatory bowel disease (IBD), rheumatoid arthritis, and Alzheimer's disease (AD). By increasing the ratio of (n-3) : (n-6) PUFA in the Western diet, reductions may be achieved in the incidence of these chronic inflammatory diseases.
Collapse
Affiliation(s)
- E. Patterson
- Alimentary Pharmabiotic Centre, Biosciences Institute, County Cork, Ireland
- Teagasc Food Research Centre, Biosciences Department, Moorepark, Fermoy, County Cork, Ireland
| | - R. Wall
- Alimentary Pharmabiotic Centre, Biosciences Institute, County Cork, Ireland
- Teagasc Food Research Centre, Biosciences Department, Moorepark, Fermoy, County Cork, Ireland
| | - G. F. Fitzgerald
- Alimentary Pharmabiotic Centre, Biosciences Institute, County Cork, Ireland
- Department of Microbiology, University College Cork, County Cork, Ireland
| | - R. P. Ross
- Alimentary Pharmabiotic Centre, Biosciences Institute, County Cork, Ireland
- Teagasc Food Research Centre, Biosciences Department, Moorepark, Fermoy, County Cork, Ireland
| | - C. Stanton
- Alimentary Pharmabiotic Centre, Biosciences Institute, County Cork, Ireland
- Teagasc Food Research Centre, Biosciences Department, Moorepark, Fermoy, County Cork, Ireland
| |
Collapse
|
57
|
Bechmann LP, Hannivoort RA, Gerken G, Hotamisligil GS, Trauner M, Canbay A. The interaction of hepatic lipid and glucose metabolism in liver diseases. J Hepatol 2012; 56:952-64. [PMID: 22173168 DOI: 10.1016/j.jhep.2011.08.025] [Citation(s) in RCA: 646] [Impact Index Per Article: 53.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 08/09/2011] [Accepted: 08/10/2011] [Indexed: 12/31/2022]
Abstract
It is widely known that the liver is a central organ in lipogenesis, gluconeogenesis and cholesterol metabolism. However, over the last decades, a variety of pathological conditions highlighted the importance of metabolic functions within the diseased liver. As observed in Western societies, an increase in the prevalence of obesity and the metabolic syndrome promotes pathophysiological changes that cause non-alcoholic fatty liver disease (NAFLD). NAFLD increases the susceptibility of the liver to acute liver injury and may lead to cirrhosis and hepatocellular cancer. Alterations in insulin response, β-oxidation, lipid storage and transport, autophagy and an imbalance in chemokines and nuclear receptor signaling are held accountable for these changes. Furthermore, recent studies revealed a role for lipid accumulation in inflammation and ER stress in the clinical context of liver regeneration and hepatic carcinogenesis. This review focuses on novel findings related to nuclear receptor signaling - including the vitamin D receptor and the liver receptor homolog 1 - in hepatic lipid and glucose uptake, storage and metabolism in the clinical context of NAFLD, liver regeneration, and cancer.
Collapse
Affiliation(s)
- Lars P Bechmann
- Department of Gastroenterology and Hepatology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | | | | | | | | | | |
Collapse
|
58
|
Nutrition and nonalcoholic Fatty liver disease: the significance of cholesterol. Int J Hepatol 2012; 2012:925807. [PMID: 22550592 PMCID: PMC3328950 DOI: 10.1155/2012/925807] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 01/30/2012] [Indexed: 12/21/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease that ranges in severity from simple steatosis to cirrhosis. NAFLD is considered to be associated with hepatic metabolic disorders, resulting in overaccumulation of fatty acids/triglycerides and cholesterol. The pathogenesis and progression of NAFLD are generally explained by the "two-hit theory." Most studies of lipid metabolism in the NAFLD liver have focused on the metabolism of fatty acids/triglycerides; therefore, the impact of cholesterol metabolism is still ambiguous. In this paper, we review recent studies on NAFLD from the viewpoint of hepatic lipid metabolism-associated factors and discuss the impact of disordered cholesterol metabolism in the etiology of NAFLD. The clinical significance of managing cholesterol metabolism, an option for the treatment of NAFLD, is also discussed.
Collapse
|
59
|
Cellular mechanism of insulin resistance in nonalcoholic fatty liver disease. Proc Natl Acad Sci U S A 2011; 108:16381-5. [PMID: 21930939 DOI: 10.1073/pnas.1113359108] [Citation(s) in RCA: 405] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Insulin resistance is associated with nonalcoholic fatty liver disease (NAFLD) and is a major factor in the pathogenesis of type 2 diabetes. The development of hepatic insulin resistance has been ascribed to multiple causes, including inflammation, endoplasmic reticulum (ER) stress, and accumulation of hepatocellular lipids in animal models of NAFLD. However, it is unknown whether these same cellular mechanisms link insulin resistance to hepatic steatosis in humans. To examine the cellular mechanisms that link hepatic steatosis to insulin resistance, we comprehensively assessed each of these pathways by using flash-frozen liver biopsies obtained from 37 obese, nondiabetic individuals and correlating key hepatic and plasma markers of inflammation, ER stress, and lipids with the homeostatic model assessment of insulin resistance index. We found that hepatic diacylglycerol (DAG) content in cytoplasmic lipid droplets was the best predictor of insulin resistance (R = 0.80, P < 0.001), and it was responsible for 64% of the variability in insulin sensitivity. Hepatic DAG content was also strongly correlated with activation of hepatic PKCε (R = 0.67, P < 0.001), which impairs insulin signaling. In contrast, there was no significant association between insulin resistance and other putative lipid metabolites or plasma or hepatic markers of inflammation. ER stress markers were only partly correlated with insulin resistance. In conclusion, these data show that hepatic DAG content in lipid droplets is the best predictor of insulin resistance in humans, and they support the hypothesis that NAFLD-associated hepatic insulin resistance is caused by an increase in hepatic DAG content, which results in activation of PKCε.
Collapse
|
60
|
Sørensen LP, Søndergaard E, Nellemann B, Christiansen JS, Gormsen LC, Nielsen S. Increased VLDL-triglyceride secretion precedes impaired control of endogenous glucose production in obese, normoglycemic men. Diabetes 2011; 60:2257-64. [PMID: 21810597 PMCID: PMC3161323 DOI: 10.2337/db11-0040] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE To assess basal and insulin-mediated VLDL-triglyceride (TG) kinetics and the relationship between VLDL-TG secretion and hepatic insulin resistance assessed by endogenous glucose production (EGP) in obese and lean men. RESEARCH DESIGN AND METHODS A total of 12 normoglycemic, obese (waist-to-hip ratio >0.9, BMI >30 kg/m(2)) and 12 lean (BMI 20-25 kg/m(2)) age-matched men were included. Ex vivo-labeled [1-(14)C]VLDL-TGs and [3-(3)H]glucose were infused postabsorptively and during a hyperinsulinemic-euglycemic clamp to determine VLDL-TG kinetics and EGP. Body composition was determined by dual X-ray absorptiometry and computed tomography scanning. Energy expenditure and substrate oxidation rates were measured by indirect calorimetry. RESULTS Basal VLDL-TG secretion rates were increased in obese compared with lean men (1.25 ± 0.34 vs. 0.86 ± 0.34 μmol/kg fat-free mass [FFM]/min; P = 0.011), whereas there was no difference in clearance rates (150 ± 56 vs. 162 ± 77 mL/min; P = NS), resulting in greater VLDL-TG concentrations (0.74 ± 0.40 vs. 0.38 ± 0.20 mmol/L; P = 0.011). The absolute insulin-mediated suppression of VLDL-TG secretion was similar in the groups. However, the percentage reduction (-36 ± 18 vs. -54 ± 10%; P = 0.008) and achieved VLDL-TG secretion rates (0.76 ± 0.20 vs. 0.41 ± 0.19 μmol/kg FFM/min; P < 0.001) were impaired in obese men. Furthermore, clearance rates decreased significantly in obese men, but there was no significant change in lean men (-17 ± 18 vs. 7 ± 20%; P = 0.007), resulting in less percentage reduction of VLDL-TG concentrations in obese men (-22 ± 20 vs. -56 ± 11%; P < 0.001). Insulin-suppressed EGP was similar (0.4 [0.0-0.8] vs. 0.1 [0.0-1.2] mg/kg FFM/min (median [range]); P = NS), and the percentage reduction was equivalent (-80% [57-98] vs. -98% [49-100], P = NS). Insulin-mediated glucose disposal was significantly reduced in obese men. CONCLUSIONS Basal VLDL-TG secretion rates are increased in normoglycemic but insulin-resistant, obese men, resulting in hypertriglyceridemia. Insulin-mediated suppression of EGP is preserved in obese men, whereas suppression of VLDL-TG secretion is less pronounced in obese men. Compared with EGP, the inability to achieve suppression of VLDL-TG secretions to a level similar to control subjects during hyperinsulinemia seems to be an early manifestation in male obesity.
Collapse
Affiliation(s)
- Lars P. Sørensen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Esben Søndergaard
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Birgitte Nellemann
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Jens S. Christiansen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Lars C. Gormsen
- Department of Nuclear Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Søren Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus, Denmark
- Corresponding author: Søren Nielsen,
| |
Collapse
|
61
|
Semple RK, Savage DB, Cochran EK, Gorden P, O'Rahilly S. Genetic syndromes of severe insulin resistance. Endocr Rev 2011; 32:498-514. [PMID: 21536711 DOI: 10.1210/er.2010-0020] [Citation(s) in RCA: 207] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Insulin resistance is among the most prevalent endocrine derangements in the world, and it is closely associated with major diseases of global reach including diabetes mellitus, atherosclerosis, nonalcoholic fatty liver disease, and ovulatory dysfunction. It is most commonly found in those with obesity but may also occur in an unusually severe form in rare patients with monogenic defects. Such patients may loosely be grouped into those with primary disorders of insulin signaling and those with defects in adipose tissue development or function (lipodystrophy). The severe insulin resistance of both subgroups puts patients at risk of accelerated complications and poses severe challenges in clinical management. However, the clinical disorders produced by different genetic defects are often biochemically and clinically distinct and are associated with distinct risks of complications. This means that optimal management of affected patients should take into account the specific natural history of each condition. In clinical practice, they are often underdiagnosed, however, with low rates of identification of the underlying genetic defect, a problem compounded by confusing and overlapping nomenclature and classification. We now review recent developments in understanding of genetic forms of severe insulin resistance and/or lipodystrophy and suggest a revised classification based on growing knowledge of the underlying pathophysiology.
Collapse
Affiliation(s)
- Robert K Semple
- Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom.
| | | | | | | | | |
Collapse
|
62
|
Dudley KJ, Sloboda DM, Connor KL, Beltrand J, Vickers MH. Offspring of mothers fed a high fat diet display hepatic cell cycle inhibition and associated changes in gene expression and DNA methylation. PLoS One 2011; 6:e21662. [PMID: 21779332 PMCID: PMC3133558 DOI: 10.1371/journal.pone.0021662] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 06/06/2011] [Indexed: 02/07/2023] Open
Abstract
The association between an adverse early life environment and increased susceptibility to later-life metabolic disorders such as obesity, type 2 diabetes and cardiovascular disease is described by the developmental origins of health and disease hypothesis. Employing a rat model of maternal high fat (MHF) nutrition, we recently reported that offspring born to MHF mothers are small at birth and develop a postnatal phenotype that closely resembles that of the human metabolic syndrome. Livers of offspring born to MHF mothers also display a fatty phenotype reflecting hepatic steatosis and characteristics of non-alcoholic fatty liver disease. In the present study we hypothesised that a MHF diet leads to altered regulation of liver development in offspring; a derangement that may be detectable during early postnatal life. Livers were collected at postnatal days 2 (P2) and 27 (P27) from male offspring of control and MHF mothers (n = 8 per group). Cell cycle dynamics, measured by flow cytometry, revealed significant G0/G1 arrest in the livers of P2 offspring born to MHF mothers, associated with an increased expression of the hepatic cell cycle inhibitor Cdkn1a. In P2 livers, Cdkn1a was hypomethylated at specific CpG dinucleotides and first exon in offspring of MHF mothers and was shown to correlate with a demonstrable increase in mRNA expression levels. These modifications at P2 preceded observable reductions in liver weight and liver∶brain weight ratio at P27, but there were no persistent changes in cell cycle dynamics or DNA methylation in MHF offspring at this time. Since Cdkn1a up-regulation has been associated with hepatocyte growth in pathologic states, our data may be suggestive of early hepatic dysfunction in neonates born to high fat fed mothers. It is likely that these offspring are predisposed to long-term hepatic dysfunction.
Collapse
Affiliation(s)
- Kevin J. Dudley
- Liggins Institute and the National Research Centre for Growth and Development, University of Auckland, Auckland, New Zealand
| | - Deborah M. Sloboda
- Liggins Institute and the National Research Centre for Growth and Development, University of Auckland, Auckland, New Zealand
| | - Kristin L. Connor
- Liggins Institute and the National Research Centre for Growth and Development, University of Auckland, Auckland, New Zealand
| | - Jacques Beltrand
- Liggins Institute and the National Research Centre for Growth and Development, University of Auckland, Auckland, New Zealand
| | - Mark H. Vickers
- Liggins Institute and the National Research Centre for Growth and Development, University of Auckland, Auckland, New Zealand
- * E-mail:
| |
Collapse
|
63
|
Caviglia JM, Gayet C, Ota T, Hernandez-Ono A, Conlon DM, Jiang H, Fisher EA, Ginsberg HN. Different fatty acids inhibit apoB100 secretion by different pathways: unique roles for ER stress, ceramide, and autophagy. J Lipid Res 2011; 52:1636-51. [PMID: 21719579 DOI: 10.1194/jlr.m016931] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Although short-term incubation of hepatocytes with oleic acid (OA) stimulates secretion of apolipoprotein B100 (apoB100), exposure to higher doses of OA for longer periods inhibits secretion in association with induction of endoplasmic reticulum (ER) stress. Palmitic acid (PA) induces ER stress, but its effects on apoB100 secretion are unclear. Docosahexaenoic acid (DHA) inhibits apoB100 secretion, but its effects on ER stress have not been studied. We compared the effects of each of these fatty acids on ER stress and apoB100 secretion in McArdle RH7777 (McA) cells: OA and PA induced ER stress and inhibited apoB100 secretion at higher doses; PA was more potent because it also increased the synthesis of ceramide. DHA did not induce ER stress but was the most potent inhibitor of apoB100 secretion, acting via stimulation of autophagy. These unique effects of each fatty acid were confirmed when they were infused into C57BL6J mice. Our results suggest that when both increased hepatic secretion of VLDL apoB100 and hepatic steatosis coexist, reducing ER stress might alleviate hepatic steatosis but at the expense of increased VLDL secretion. In contrast, increasing autophagy might reduce VLDL secretion without causing steatosis.
Collapse
Affiliation(s)
- Jorge Matias Caviglia
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | | | | | | | | | | | | | | |
Collapse
|
64
|
Fowler JC, Zecchini VR, Jones PH. Intestinal activation of Notch signaling induces rapid onset hepatic steatosis and insulin resistance. PLoS One 2011; 6:e20767. [PMID: 21698231 PMCID: PMC3116826 DOI: 10.1371/journal.pone.0020767] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 05/09/2011] [Indexed: 02/07/2023] Open
Abstract
Here we investigate the effects of expressing an activated mutant of Notch (ICD-E) in an inducible transgenic mouse model. Hepatic expression of ICD-E in adult animals has no detectable phenotype, but simultaneous induction of ICD-E in both the liver and small intestine results in hepatic steatosis, lipogranuloma formation and mild insulin resistance within 96 hours. This supports work that suggests that fatty liver disease may result from disruption of the gut-liver axis. In the intestine, ICD-E expression is known to produce a transient change in the proportion of goblet cells followed by shedding of the recombinant epithelium. We report additional intestinal transcriptional changes following ICD-E expression, finding significant transcriptional down-regulation of rpL29 (ribosomal protein L29), which is implicated in the regulation of intestinal flora. These results provide further evidence of a gut-liver axis in the development of fatty liver disease and insulin resistance and validate a new model for future studies of hepatic steatosis.
Collapse
Affiliation(s)
- Joanna C. Fowler
- Medical Research Council Cancer Cell Unit, Cambridge, United Kingdom
| | | | - Philip H. Jones
- Medical Research Council Cancer Cell Unit, Cambridge, United Kingdom
- * E-mail:
| |
Collapse
|
65
|
Zanlungo S, Rigotti A, Miquel JF, Nervi F. Abnormalities of lipid metabolism, gallstone disease and gallbladder function. ACTA ACUST UNITED AC 2011. [DOI: 10.2217/clp.11.22] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
66
|
Current world literature. Curr Opin Lipidol 2011; 22:231-6. [PMID: 21562387 DOI: 10.1097/mol.0b013e328347aeca] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
67
|
Abstract
PURPOSE OF REVIEW A net retention of triacylglycerol within the liver is a prerequisite for the development of nonalcoholic fatty liver disease. The accumulation of liver fat reflects an imbalance between fatty acid input and disposal. Here we summarize recent research into understanding the fate of fatty acids within the hepatocyte. RECENT FINDINGS Several recent studies have elucidated the contribution of different sources of fatty acids to liver fat and to plasma triacylglycerol. Some recent studies have suggested that, contrary to expectations, hepatic fatty acid oxidation is upregulated in insulin-resistant individuals. A recent observation shows the potential importance of fatty acid transformation, especially desaturation, to determination of metabolic fate. These studies highlight our lack of understanding of the regulation of metabolic partitioning of fatty acids within the human liver. SUMMARY The regulation of hepatic fatty acid partitioning involves many factors; not least insulin. Insulin undoubtedly regulates the supply of fatty acids to the liver from adipose tissue; however, whether insulin has a direct intrahepatic effect on hepatic fatty acid partitioning, in humans, remains unclear. The transformation of fatty acids, by desaturases, may have an important role in aiding the disposal of saturated fatty acids via oxidative pathways. Factors that upregulate hepatic fatty acid oxidation need to be elucidated.
Collapse
Affiliation(s)
- Leanne Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK.
| | | |
Collapse
|
68
|
De Silva NMG, Freathy RM, Palmer TM, Donnelly LA, Luan J, Gaunt T, Langenberg C, Weedon MN, Shields B, Knight BA, Ward KJ, Sandhu MS, Harbord RM, McCarthy MI, Smith GD, Ebrahim S, Hattersley AT, Wareham N, Lawlor DA, Morris AD, Palmer CN, Frayling TM. Mendelian randomization studies do not support a role for raised circulating triglyceride levels influencing type 2 diabetes, glucose levels, or insulin resistance. Diabetes 2011; 60:1008-18. [PMID: 21282362 PMCID: PMC3046819 DOI: 10.2337/db10-1317] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE The causal nature of associations between circulating triglycerides, insulin resistance, and type 2 diabetes is unclear. We aimed to use Mendelian randomization to test the hypothesis that raised circulating triglyceride levels causally influence the risk of type 2 diabetes and raise normal fasting glucose levels and hepatic insulin resistance. RESEARCH DESIGN AND METHODS We tested 10 common genetic variants robustly associated with circulating triglyceride levels against the type 2 diabetes status in 5,637 case and 6,860 control subjects and four continuous outcomes (reflecting glycemia and hepatic insulin resistance) in 8,271 nondiabetic individuals from four studies. RESULTS Individuals carrying greater numbers of triglyceride-raising alleles had increased circulating triglyceride levels (SD 0.59 [95% CI 0.52-0.65] difference between the 20% of individuals with the most alleles and the 20% with the fewest alleles). There was no evidence that the carriers of greater numbers of triglyceride-raising alleles were at increased risk of type 2 diabetes (per weighted allele odds ratio [OR] 0.99 [95% CI 0.97-1.01]; P = 0.26). In nondiabetic individuals, there was no evidence that carriers of greater numbers of triglyceride-raising alleles had increased fasting insulin levels (SD 0.00 per weighted allele [95% CI -0.01 to 0.02]; P = 0.72) or increased fasting glucose levels (0.00 [-0.01 to 0.01]; P = 0.88). Instrumental variable analyses confirmed that genetically raised circulating triglyceride levels were not associated with increased diabetes risk, fasting glucose, or fasting insulin and, for diabetes, showed a trend toward a protective association (OR per 1-SD increase in log(10) triglycerides: 0.61 [95% CI 0.45-0.83]; P = 0.002). CONCLUSIONS Genetically raised circulating triglyceride levels do not increase the risk of type 2 diabetes or raise fasting glucose or fasting insulin levels in nondiabetic individuals. One explanation for our results is that raised circulating triglycerides are predominantly secondary to the diabetes disease process rather than causal.
Collapse
Affiliation(s)
- N. Maneka G. De Silva
- Genetics of Complex Traits, Institute of Biomedical and Clinical Sciences, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, U.K
| | - Rachel M. Freathy
- Genetics of Complex Traits, Institute of Biomedical and Clinical Sciences, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, U.K
| | - Tom M. Palmer
- Medical Research Council (MRC) Centre for Causal Analyses in Translational Epidemiology, School of Social
and Community Medicine, University of Bristol, Bristol, U.K
| | - Louise A. Donnelly
- Biomedical Research Institute, University of Dundee, Ninewells Hospital and Medical School, Dundee, U.K
| | - Jian'an Luan
- MRC, Epidemiology Unit, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, U.K
| | - Tom Gaunt
- Medical Research Council (MRC) Centre for Causal Analyses in Translational Epidemiology, School of Social
and Community Medicine, University of Bristol, Bristol, U.K
| | - Claudia Langenberg
- MRC, Epidemiology Unit, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, U.K
| | - Michael N. Weedon
- Genetics of Complex Traits, Institute of Biomedical and Clinical Sciences, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, U.K
| | - Beverley Shields
- Peninsula National Institute for Health Research (NIHR) Clinical Research Facility, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, U.K
| | - Beatrice A. Knight
- Peninsula National Institute for Health Research (NIHR) Clinical Research Facility, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, U.K
| | - Kirsten J. Ward
- Department of Twin Research and Genetic Epidemiology, King’s College London, St. Thomas’ Hospital Campus, London, U.K
| | - Manjinder S. Sandhu
- MRC, Epidemiology Unit, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, U.K
- Department of Public Health and Primary Care, Strangeways Research Laboratory, University of Cambridge, Cambridge, U.K
| | - Roger M. Harbord
- Medical Research Council (MRC) Centre for Causal Analyses in Translational Epidemiology, School of Social
and Community Medicine, University of Bristol, Bristol, U.K
- School of Social and Community Medicine, University of Bristol, Bristol, U.K
| | - Mark I. McCarthy
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Oxford, U.K
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, U.K
- Oxford NIHR, Biomedical Research Centre, Churchill Hospital, Oxford, U.K
| | - George Davey Smith
- Medical Research Council (MRC) Centre for Causal Analyses in Translational Epidemiology, School of Social
and Community Medicine, University of Bristol, Bristol, U.K
| | - Shah Ebrahim
- Department of Twin Research and Genetic Epidemiology, King’s College London, St. Thomas’ Hospital Campus, London, U.K
| | - Andrew T. Hattersley
- Peninsula National Institute for Health Research (NIHR) Clinical Research Facility, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, U.K
| | - Nicholas Wareham
- MRC, Epidemiology Unit, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, U.K
| | - Debbie A. Lawlor
- Medical Research Council (MRC) Centre for Causal Analyses in Translational Epidemiology, School of Social
and Community Medicine, University of Bristol, Bristol, U.K
| | - Andrew D. Morris
- Biomedical Research Institute, University of Dundee, Ninewells Hospital and Medical School, Dundee, U.K
| | - Colin N.A. Palmer
- Biomedical Research Institute, University of Dundee, Ninewells Hospital and Medical School, Dundee, U.K
| | - Timothy M. Frayling
- Genetics of Complex Traits, Institute of Biomedical and Clinical Sciences, Peninsula College of Medicine and Dentistry, University of Exeter, Exeter, U.K
- Corresponding author: Timothy M. Frayling,
| |
Collapse
|
69
|
Law JR, Patel S, Spagnoli A. Approach to lipid screening as a risk marker for cardiovascular disease in pediatric patients with diabetes. Front Endocrinol (Lausanne) 2011; 2:47. [PMID: 22649373 PMCID: PMC3355998 DOI: 10.3389/fendo.2011.00047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 09/17/2011] [Indexed: 12/02/2022] Open
Abstract
Cardiovascular disease (CVD) is a well-known complication of diabetes mellitus (DM), and patients with DM are at an increased risk for early onset of CVD. Hyperglycemia is believed to be the primary mediator in premature development of atherosclerosis in patients with DM, but there are also derangements in cholesterol levels and inflammatory markers beyond the explanation of hyperglycemia. Although clinicians often screen for dyslipidemia as part of routine care for children and adolescents with DM, many do not feel comfortable treating this condition. Multiple guidelines exist to help clinicians with the prevention, screening, and treatment of CVD risk factors in pediatric patients with DM, but the guidelines do not always agree on screening intervals or medical treatment. Furthermore, the cost-effectiveness of medication use in this population has not been established. Research has advanced our understanding of the role of other biomarkers and radiologic studies of CVD risk, but these studies do not currently have a place in routine clinical practice. It is evident that the increased CVD risk in pediatric patients with DM is complex in origin and the optimal approach to managing dyslipidemia remains unclear. Therefore, an algorithm designed at the University of North Carolina (UNC), Division of Pediatric Endocrinology, is presented to help guide clinicians through screening and treatment of dyslipidemia in youth with DM.
Collapse
Affiliation(s)
- Jennifer Rachel Law
- Division of Pediatric Endocrinology, Department of Pediatrics, University of North Carolina at Chapel HillChapel Hill, NC, USA
| | - Shipra Patel
- Division of Pediatric Endocrinology, Department of Pediatrics, University of North Carolina at Chapel HillChapel Hill, NC, USA
| | - Anna Spagnoli
- Division of Pediatric Endocrinology, Department of Pediatrics, University of North Carolina at Chapel HillChapel Hill, NC, USA
- *Correspondence: Anna Spagnoli, Division of Pediatric Endocrinology, University of North Carolina, 111 Mason Farm Road, CB 7039, Chapel Hill, NC 27599-7039, USA. e-mail:
| |
Collapse
|
70
|
Wang RH, Li C, Deng CX. Liver steatosis and increased ChREBP expression in mice carrying a liver specific SIRT1 null mutation under a normal feeding condition. Int J Biol Sci 2010; 6:682-90. [PMID: 21103071 PMCID: PMC2990071 DOI: 10.7150/ijbs.6.682] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 11/16/2010] [Indexed: 12/21/2022] Open
Abstract
SIRT1, a homolog of yeast Sir2, is a type III NAD+ dependent histone and protein deacetylase. Previous studies of mice carrying liver specific deletion of exon 4 of the Sirt1 gene revealed opposite responses of mutant mice to a high-fat diet in terms of fatty liver formation, which obscures the function of SRIT1 in liver development and lipid metabolism. To investigate this, we deleted exons 5 and 6 of Sirt1 in the liver by using a Cre-loxP approach. Western blot using an antibody to N-terminal SIRT1 does not detect a truncated protein in the liver of the mutant mice (Sirt1flox5-6/flox5-6;Alb-Cre), suggesting a null mutation for SIRT1 is generated in the liver. Unlike the previously reported phenotypes, the Sirt1flox5-6/flox5-6;Alb-Cre mice develop fatty liver under a normal feeding condition. The disease starts at two months of age and incidence increases as the animals become older, affecting 78% of them when they are over one year of age. We showed that the steatosis is accompanied by altered expression of a number of genes, including increased expression of ChREBP, which acts as one of the central determinants of lipid synthesis in the liver. This data uncovers an important role of SIRT1 in regulating lipid metabolism in the liver, and the SIRT1 mutant mice may serve as an animal model for studying human fatty liver disease and facilitate the development of effective therapeutic approach for the disease.
Collapse
Affiliation(s)
- Rui-Hong Wang
- Genetics of Development and Disease Branch, 10/9N105, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, MD 20892, USA
| | | | | |
Collapse
|
71
|
Abstract
A nem alkoholos zsírmáj betegség (NAFLD = nonalcoholic fatty liver disease) az „iparilag fejlett” országok felnőtt lakosságának 30%-ában észlelhető. Előrehaladott, súlyosabb formája a nem alkoholos steatohepatitis (NASH = nonalcoholic steatohepatitis), amelyből az esetek 20%-ában cirrhosis alakul ki, a kialakult cirrhosis mintegy 30–40%-a májeredetű halálhoz, elsősorban hepatocellularis carcinomához vezethet. Az NAFLD-t sokan a metabolikus szindróma májbeli manifesztációjának tartják, e két jelenség kapcsolatát tekintjük át, különös tekintettel a hasi elhízás, az inzulinrezisztencia, az oxidatív stressz és a csökkent antioxidáns védelem kóroki szerepére. A májsejtek trigliceridtartalmának növekedése együtt jár az egész szervezet, illetve a máj inzulinrezisztenciájával. Klasszikus tyúk–tojás probléma: a lipidlerakódás oka az inzulinrezisztencia, vagy az inzulinrezisztencia az ectopiás lipidfelhalmozódás következménye? A patogenetikai történések egy lehetséges sorrendje: megnövekedett zsírsavfluxus, a májbeli zsírsavkínálat növekedése → VLDL-túltermelődés, atherogen dyslipidaemia → a zsírsavak fokozott oxidációja és peroxidációja, enormis szabadgyök-terhelés → az antioxidáns védekezőrendszer kimerülése → a gyulladást és az immunválaszt kiváltó mediátorok „cunamiszerű” kiáramlása → a fibrosis progresszióját elősegítő transzkripciós és transzlációs változások → carcinogenesis. Az NAFLD és a metabolikus szindróma egyaránt része a globális kardiometabolikus kockázatnak, így lényeges a korai felismerés, és – amennyiben lehetséges a kezelés – ez ma a metabolikus szindróma részelemeinek kezelési ajánlásaiban testesül meg. Orv. Hetil., 2010,
47,
1946–1950.
Collapse
Affiliation(s)
- Lajos Szollár
- 1 Semmelweis Egyetem, Általános Orvostudományi Kar Kórélettani Intézet Budapest Nagyvárad tér 4. 1089
| |
Collapse
|
72
|
Torres DM, Harrison SA. Nonalcoholic fatty liver disease: is it all in the genes? Hepatology 2010; 52:1851-4. [PMID: 21038421 DOI: 10.1002/hep.24020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
|