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Effenberger M, Grander C, Grabherr F, Tilg H. Nonalcoholic Fatty Liver Disease and the Intestinal Microbiome: An Inseparable Link. J Clin Transl Hepatol 2023; 11:1498-1507. [PMID: 38161503 PMCID: PMC10752805 DOI: 10.14218/jcth.2023.00069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 04/21/2023] [Accepted: 07/18/2023] [Indexed: 01/03/2024] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) particularly affects patients with type 2 diabetes and obesity. The incidence of NAFLD has increased significantly over the last decades and is now pandemically across the globe. It is a complex systemic disease comprising hepatic lipid accumulation, inflammation, lipotoxicity, gut dysbiosis, and insulin resistance as main features and with the potential to progress to cirrhosis and hepatocellular carcinoma (HCC). In numerous animal and human studies the gut microbiota plays a key role in the pathogenesis of NAFLD, NAFLD-cirrhosis and NAFLD-associated HCC. Lipotoxicity is the driver of inflammation, insulin resistance, and liver injury. Likewise, western diet, obesity, and metabolic disorders may alter the gut microbiota, which activates innate and adaptive immune responses and fuels hereby hepatic and systemic inflammation. Indigestible carbohydrates are fermented by the gut microbiota to produce important metabolites, such as short-chain fatty acids and succinate. Numerous animal and human studies suggested a pivotal role of these metabolites in the progression of NAFLD and its comorbidities. Though, modification of the gut microbiota and/or the metabolites could even be beneficial in patients with NAFLD, NAFLD-cirrhosis, and NAFLD-associated HCC. In this review we collect the evidence that exogenous and endogenous hits drive liver injury in NAFLD and propel liver fibrosis and the progressing to advanced disease stages. NAFLD can be seen as the product of a complex interplay between gut microbiota, the immune response and metabolism. Thus, the challenge will be to understand its pathogenesis and to develop new therapeutic strategies.
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Affiliation(s)
- Maria Effenberger
- Department of Internal Medicine I, Gastroenterology, Hepatology, Endocrinology and Metabolism, Medical University of Innsbruck, Innsbruck, Austria
| | - Christoph Grander
- Department of Internal Medicine I, Gastroenterology, Hepatology, Endocrinology and Metabolism, Medical University of Innsbruck, Innsbruck, Austria
| | - Felix Grabherr
- Department of Internal Medicine I, Gastroenterology, Hepatology, Endocrinology and Metabolism, Medical University of Innsbruck, Innsbruck, Austria
| | - Herbert Tilg
- Department of Internal Medicine I, Gastroenterology, Hepatology, Endocrinology and Metabolism, Medical University of Innsbruck, Innsbruck, Austria
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Vesković M, Šutulović N, Hrnčić D, Stanojlović O, Macut D, Mladenović D. The Interconnection between Hepatic Insulin Resistance and Metabolic Dysfunction-Associated Steatotic Liver Disease-The Transition from an Adipocentric to Liver-Centric Approach. Curr Issues Mol Biol 2023; 45:9084-9102. [PMID: 37998747 PMCID: PMC10670061 DOI: 10.3390/cimb45110570] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/01/2023] [Accepted: 11/09/2023] [Indexed: 11/25/2023] Open
Abstract
The central mechanism involved in the pathogenesis of MAFLD is insulin resistance with hyperinsulinemia, which stimulates triglyceride synthesis and accumulation in the liver. On the other side, triglyceride and free fatty acid accumulation in hepatocytes promotes insulin resistance via oxidative stress, endoplasmic reticulum stress, lipotoxicity, and the increased secretion of hepatokines. Cytokines and adipokines cause insulin resistance, thus promoting lipolysis in adipose tissue and ectopic fat deposition in the muscles and liver. Free fatty acids along with cytokines and adipokines contribute to insulin resistance in the liver via the activation of numerous signaling pathways. The secretion of hepatokines, hormone-like proteins, primarily by hepatocytes is disturbed and impairs signaling pathways, causing metabolic dysregulation in the liver. ER stress and unfolded protein response play significant roles in insulin resistance aggravation through the activation of apoptosis, inflammatory response, and insulin signaling impairment mediated via IRE1/PERK/ATF6 signaling pathways and the upregulation of SREBP 1c. Circadian rhythm derangement and biological clock desynchronization are related to metabolic disorders, insulin resistance, and NAFLD, suggesting clock genes as a potential target for new therapeutic strategies. This review aims to summarize the mechanisms of hepatic insulin resistance involved in NAFLD development and progression.
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Affiliation(s)
- Milena Vesković
- Institute of Pathophysiology “Ljubodrag Buba Mihailovic”, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia;
| | - Nikola Šutulović
- Institute of Medical Physiology “Richard Burian”, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (N.Š.); (D.H.); (O.S.)
| | - Dragan Hrnčić
- Institute of Medical Physiology “Richard Burian”, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (N.Š.); (D.H.); (O.S.)
| | - Olivera Stanojlović
- Institute of Medical Physiology “Richard Burian”, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia; (N.Š.); (D.H.); (O.S.)
| | - Djuro Macut
- Clinic of Endocrinology, Diabetes and Metabolic Diseases, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia;
| | - Dušan Mladenović
- Institute of Pathophysiology “Ljubodrag Buba Mihailovic”, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia;
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Griffett K, Burris TP. Development of LXR inverse agonists to treat MAFLD, NASH, and other metabolic diseases. Front Med (Lausanne) 2023; 10:1102469. [PMID: 36817797 PMCID: PMC9932051 DOI: 10.3389/fmed.2023.1102469] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 01/16/2023] [Indexed: 02/04/2023] Open
Abstract
Activation of LXR activity by synthetic agonists has been the focus of many drug discovery efforts with a focus on treatment of dyslipidemia and atherosclerosis. Many agonists have been developed, but all have been hindered due to their ability to efficaciously stimulate de novo lipogenesis. Here, we review the development of LXR inverse agonists that were originally optimized for their ability to enable recruitment of corepressors leading to silencing of genes that drive de novo lipogenesis. Such compounds have efficacy in animal models of MAFLD, dyslipidemia, and cancer. Several classes of LXR inverse agonists have been identified and one is now in clinical trials for treatment of severe dyslipidemia.
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Affiliation(s)
- Kristine Griffett
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL, United States
| | - Thomas P. Burris
- The University of Florida Genetics Institute, Gainesville, FL, United States,*Correspondence: Thomas P. Burris,
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Jang YS, Joo HJ, Park YS, Park EC, Jang SI. Association between smoking cessation and non-alcoholic fatty liver disease using NAFLD liver fat score. Front Public Health 2023; 11:1015919. [PMID: 36875368 PMCID: PMC9982128 DOI: 10.3389/fpubh.2023.1015919] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 01/27/2023] [Indexed: 02/19/2023] Open
Abstract
Background Smoking is well known to be associated with a higher prevalence and incidence of liver diseases such as advanced fibrosis. However, the impact of smoking on developing nonalcoholic fatty liver disease remains controversial, and clinical data on this is limited. Therefore, this study aimed to investigate the association between smoking history and nonalcoholic fatty liver disease (NAFLD). Methods Data from the Korea National Health and Nutrition Examination Survey 2019-2020 were used for the analysis. NAFLD was diagnosed according to an NAFLD liver fat score of >-0.640. Smoking status was classified as into nonsmokers, ex-smokers, and current smokers. Multiple logistic regression analysis was conducted to examine the association between smoking history and NAFLD in the South Korean population. Results In total, 9,603 participants were enrolled in this study. The odds ratio (OR) for having NAFLD in ex-smokers and current smokers in males was 1.12 (95% confidence interval [CI]: 0.90-1.41) and 1.38 (95% CI: 1.08-1.76) compared to that in nonsmokers, respectively. The OR increased in magnitude with smoking status. Ex-smokers who ceased smoking for <10 years (OR: 1.33, 95% CI: 1.00-1.77) were more likely to have a strong correlation with NAFLD. Furthermore, NAFLD had a dose-dependent positive effect on pack-years, which was 10 to 20 (OR: 1.39, 95% CI: 1.04-1.86) and over 20 (OR: 1.51, 95% CI: 1.14-2.00). Conclusion This study found that smoking may contribute to NAFLD. Our study suggests cessation of smoking may help management of NAFLD.
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Affiliation(s)
- Yun Seo Jang
- Department of Public Health, Graduate School, Yonsei University, Seoul, Republic of Korea.,Institute of Health Services Research, Yonsei University, Seoul, Republic of Korea
| | - Hye Jin Joo
- Department of Public Health, Graduate School, Yonsei University, Seoul, Republic of Korea.,Institute of Health Services Research, Yonsei University, Seoul, Republic of Korea
| | - Yu Shin Park
- Department of Public Health, Graduate School, Yonsei University, Seoul, Republic of Korea.,Institute of Health Services Research, Yonsei University, Seoul, Republic of Korea
| | - Eun-Cheol Park
- Institute of Health Services Research, Yonsei University, Seoul, Republic of Korea.,Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Sung-In Jang
- Institute of Health Services Research, Yonsei University, Seoul, Republic of Korea.,Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
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Pemafibrate improves liver dysfunction and non-invasive surrogates for liver fibrosis in patients with non-alcoholic fatty liver disease with hypertriglyceridemia: a multicenter study. Hepatol Int 2022; 17:606-614. [PMID: 36583842 DOI: 10.1007/s12072-022-10453-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 11/04/2022] [Indexed: 12/31/2022]
Abstract
BACKGROUND This retrospective, multicenter study evaluated the effect of pemafibrate treatment on liver function and fibrosis by liver function tests (LFTs) and various fibrotic biomarkers including FibroScan in non-alcoholic fatty liver disease (NAFLD) with hypertriglyceridemia. METHODS A total of 138 NAFLD patients treated with pemafibrate at three hospitals between September 2018 and April 2021 were included. To evaluate the effect of pemafibrate treatment, FibroScan-aspartate aminotransferase (FAST) score, a novel index of steatohepatitis that can be calculated based on the aspartate aminotransferase (AST) value, controlled attenuation parameter (CAP), and liver stiffness measurement (LSM) was used. RESULTS Serum TG levels were significantly decreased 4 weeks after pemafibrate treatment (p = 0.003). The levels of AST (p = 0.038), alanine aminotransferase (ALT) (p = 0.003), and gamma-glutamyl transferase (GGT) (p = 0.047) also significantly diminished 12 weeks after pemafibrate administration compared to before administration (p < 0.05). However, serum HDL-cholesterol (p = 0.193), LDL-cholesterol (p = 0.967), and eGFR (p = 0.909) levels were not significantly altered 12 weeks after pemafibrate administration. In addition, the fibrosis biomarkers' Type IV collagen (p = 0.753) and FIB-4 index (p = 0.333) did not significantly differ, while Autotaxin (p = 0.006) and the AST-to-platelet ratio index (APRI) (p = 0.003) significantly decreased 48 weeks after pemafibrate administration. No significant reductions in LSM (p = 0.959) and CAP (p = 0.266) were detected using FibroScan 48 weeks after pemafibrate administration. FAST score was significantly improved (p = 0.0475). CONCLUSION Pemafibrate improved LFTs, including fibrotic biomarkers and FAST score, due to the hepatic anti-inflammatory effect, suggesting that pemafibrate may prevent disease progression in NAFLD patients with hypertriglyceridemia.
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NAFLD-Related Hepatocarcinoma: The Malignant Side of Metabolic Syndrome. Cells 2021; 10:cells10082034. [PMID: 34440803 PMCID: PMC8391372 DOI: 10.3390/cells10082034] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 08/02/2021] [Accepted: 08/04/2021] [Indexed: 12/11/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is the seventh most common cancer worldwide and the second leading cause of cancer-related mortality. HCC typically arises within a cirrhotic liver, but in about 20% of cases occurs in absence of cirrhosis. Among non-cirrhotic risk factors, non-alcoholic fatty liver disease (NAFLD) currently represents the most important emerging cause of HCC in developed countries. It has been estimated that annual incidence of HCC among patients with non-cirrhotic NAFLD is approximately 0.1-1.3 per 1000 patients/year and ranges from 0.5% to 2.6% among patients with non-alcoholic steatohepatitis (NASH) cirrhosis. However, only a few clinical trials enrolling HCC patients actually distinguished NAFLD/NASH-related cases from other non-cirrhotic causes and therefore evidence is still lacking in this subset of patients. This review aims to describe the biology underpinning NAFLD development, to investigate the main molecular pathways involved in its progression to NASH and HCC and to describe how different pathogenetic mechanisms underlying the onset of HCC can have an impact in clinical practice. We hereby also provide an overview of current HCC treatment options, with a particular focus on the available data on NAFLD-related cases in practice-changing clinical trials.
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Wang B, Wang B, Yang Y, Xu J, Hong M, Xia M, Li X, Gao X. Thyroid function and non-alcoholic fatty liver disease in hyperthyroidism patients. BMC Endocr Disord 2021; 21:27. [PMID: 33602203 PMCID: PMC7890885 DOI: 10.1186/s12902-021-00694-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 02/09/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Although thyroid function has been demonstrated to be associated with non-alcoholic fatty liver disease (NAFLD) in different population, the prevalence and features of NAFLD in hyperthyroidism have not been reported. The present study aims to investigate the prevalence of NAFLD and association of thyroid function and NAFLD in hyperthyroidism patients. METHODS This cross-sectional study was performed in Zhongshan Hospital, Fudan University, China. A total 117 patients with hyperthyroidism were consecutively recruited from 2014 to 2015. Thyroid function and other clinical features were measured, liver fat content was measured by color Doppler ultrasonically, NAFLD was defined in patients with liver fat content more than 9.15%. Statistical analyses were performed with SPSS software package version 13.0. RESULTS The prevalence of NAFLD was 11.97% in hyperthyroidism. Patient with NAFLD had lower free triiodothyronine (FT3) and free thyroxine (FT4) levels than patients without NAFLD (P < 0.05). After adjusting for age, gender, metabolic parameters and inflammation factors, higher FT3 were associated with lower liver fat content (β = - 0.072, P = 0.009) and decreased odds ratio of NAFLD (OR = 0.267, 95%CI 0.087-0.817, P = 0.021). CONCLUSIONS FT3 level was negatively associated with the liver fat content in this population. These results may provide new evidence in the role of thyroid hormone on the regulation of liver fat content and NAFLD.
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Affiliation(s)
- Bairong Wang
- Present address: The Department of Endocrinology, Zhongshan hospital, Fudan University, NO. 180 Fenglin Road, Shanghai, 200032, China
- Department of Endocrinology and Metabolism, Jinjiang Municipal Hospital, Jinjiang, 362200, China
| | - Baomin Wang
- Present address: The Department of Endocrinology, Zhongshan hospital, Fudan University, NO. 180 Fenglin Road, Shanghai, 200032, China
| | - Yumei Yang
- Present address: The Department of Endocrinology, Zhongshan hospital, Fudan University, NO. 180 Fenglin Road, Shanghai, 200032, China
| | - Jing Xu
- Present address: The Department of Endocrinology, Zhongshan hospital, Fudan University, NO. 180 Fenglin Road, Shanghai, 200032, China
| | - Mengyang Hong
- Present address: The Department of Endocrinology, Zhongshan hospital, Fudan University, NO. 180 Fenglin Road, Shanghai, 200032, China
| | - Mingfeng Xia
- Present address: The Department of Endocrinology, Zhongshan hospital, Fudan University, NO. 180 Fenglin Road, Shanghai, 200032, China
| | - Xiaomu Li
- Present address: The Department of Endocrinology, Zhongshan hospital, Fudan University, NO. 180 Fenglin Road, Shanghai, 200032, China.
| | - Xin Gao
- Present address: The Department of Endocrinology, Zhongshan hospital, Fudan University, NO. 180 Fenglin Road, Shanghai, 200032, China
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Rinaldi L, Pafundi PC, Galiero R, Caturano A, Morone MV, Silvestri C, Giordano M, Salvatore T, Sasso FC. Mechanisms of Non-Alcoholic Fatty Liver Disease in the Metabolic Syndrome. A Narrative Review. Antioxidants (Basel) 2021; 10:270. [PMID: 33578702 PMCID: PMC7916383 DOI: 10.3390/antiox10020270] [Citation(s) in RCA: 97] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 02/04/2021] [Accepted: 02/08/2021] [Indexed: 02/07/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS) are two different entities sharing common clinical and physio-pathological features, with insulin resistance (IR) as the most relevant. Large evidence leads to consider it as a risk factor for cardiovascular disease, regardless of age, sex, smoking habit, cholesterolemia, and other elements of MS. Therapeutic strategies remain still unclear, but lifestyle modifications (diet, physical exercise, and weight loss) determine an improvement in IR, MS, and both clinical and histologic liver picture. NAFLD and IR are bidirectionally correlated and, consequently, the development of pre-diabetes and diabetes is the most direct consequence at the extrahepatic level. In turn, type 2 diabetes is a well-known risk factor for multiorgan damage, including an involvement of cardiovascular system, kidney and peripheral nervous system. The increased MS incidence worldwide, above all due to changes in diet and lifestyle, is associated with an equally significant increase in NAFLD, with a subsequent rise in both morbidity and mortality due to both metabolic, hepatic and cardiovascular diseases. Therefore, the slowdown in the increase of the "bad company" constituted by MS and NAFLD, with all the consequent direct and indirect costs, represents one of the main challenges for the National Health Systems.
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Affiliation(s)
- Luca Rinaldi
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, Piazza Luigi Miraglia 2, 80138 Naples, Italy; (L.R.); (P.C.P.); (R.G.); (A.C.); (C.S.); (M.G.)
| | - Pia Clara Pafundi
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, Piazza Luigi Miraglia 2, 80138 Naples, Italy; (L.R.); (P.C.P.); (R.G.); (A.C.); (C.S.); (M.G.)
| | - Raffaele Galiero
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, Piazza Luigi Miraglia 2, 80138 Naples, Italy; (L.R.); (P.C.P.); (R.G.); (A.C.); (C.S.); (M.G.)
| | - Alfredo Caturano
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, Piazza Luigi Miraglia 2, 80138 Naples, Italy; (L.R.); (P.C.P.); (R.G.); (A.C.); (C.S.); (M.G.)
| | - Maria Vittoria Morone
- Department of Experimental Medicine, Section of Microbiology, University of Campania Luigi Vanvitelli, Piazza Luigi Miraglia 2, 80138 Naples, Italy;
| | - Chiara Silvestri
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, Piazza Luigi Miraglia 2, 80138 Naples, Italy; (L.R.); (P.C.P.); (R.G.); (A.C.); (C.S.); (M.G.)
| | - Mauro Giordano
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, Piazza Luigi Miraglia 2, 80138 Naples, Italy; (L.R.); (P.C.P.); (R.G.); (A.C.); (C.S.); (M.G.)
| | - Teresa Salvatore
- Department of Precision Medicine, University of Campania Luigi Vanvitelli, Via De Crecchio 7, 80138 Naples, Italy;
| | - Ferdinando Carlo Sasso
- Department of Advanced Medical and Surgical Sciences, University of Campania Luigi Vanvitelli, Piazza Luigi Miraglia 2, 80138 Naples, Italy; (L.R.); (P.C.P.); (R.G.); (A.C.); (C.S.); (M.G.)
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Abstract
Non-Alcoholic Fatty Liver Disease (NAFLD) is caused by the accumulation of fat in over 5% of hepatocytes in the absence of alcohol consumption. NAFLD is considered the hepatic manifestation of metabolic syndrome (MS). Recently, an expert consensus suggested as more appropriate the term MAFLD (metabolic-associated fatty liver disease). Insulin resistance (IR) plays a key role in the development of NAFLD, as it causes an increase in hepatic lipogenesis and an inhibition of adipose tissue lipolysis. Beyond the imbalance of adipokine levels, the increase in the mass of visceral adipose tissue also determines an increase in free fatty acid (FFA) levels. In turn, an excess of FFA is able to determine IR through the inhibition of the post-receptor insulin signal. Adipocytes secrete chemokines, which are able to enroll macrophages inside the adipose tissue, responsible, in turn, for the increased levels of TNF-α. The latter, as well as resistin and other pro-inflammatory cytokines such as IL-6, enhances insulin resistance and correlates with endothelial dysfunction and an increased cardiovascular (CV) risk. In this review, the role of diet, intestinal microbiota, genetic and epigenetic factors, low-degree chronic systemic inflammation, mitochondrial dysfunction, and endoplasmic reticulum stress on NAFLD have been addressed. Finally, the clinical impact of NAFLD on cardiovascular and renal outcomes, and its direct link with type 2 diabetes have been discussed.
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Immunity as Cornerstone of Non-Alcoholic Fatty Liver Disease: The Contribution of Oxidative Stress in the Disease Progression. Int J Mol Sci 2021; 22:ijms22010436. [PMID: 33406763 PMCID: PMC7795122 DOI: 10.3390/ijms22010436] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/18/2020] [Accepted: 12/30/2020] [Indexed: 12/12/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of metabolic syndrome and has become the major cause of chronic liver disease, especially in western countries. NAFLD encompasses a wide spectrum of hepatic histological alterations, from simple steatosis to steatohepatitis and cirrhosis with a potential development of hepatocellular carcinoma. Non-alcoholic steatohepatitis (NASH) is characterized by lobular inflammation and fibrosis. Several studies reported that insulin resistance, redox unbalance, inflammation, and lipid metabolism dysregulation are involved in NAFLD progression. However, the mechanisms beyond the evolution of simple steatosis to NASH are not clearly understood yet. Recent findings suggest that different oxidized products, such as lipids, cholesterol, aldehydes and other macromolecules could drive the inflammation onset. On the other hand, new evidence indicates innate and adaptive immunity activation as the driving force in establishing liver inflammation and fibrosis. In this review, we discuss how immunity, triggered by oxidative products and promoting in turn oxidative stress in a vicious cycle, fuels NAFLD progression. Furthermore, we explored the emerging importance of immune cell metabolism in determining inflammation, describing the potential application of trained immune discoveries in the NASH pathological context.
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Lipidomic profiling reveals triacylglycerol accumulation in the liver during pregnane X receptor activation-induced hepatomegaly. J Pharm Biomed Anal 2020; 195:113851. [PMID: 33387840 DOI: 10.1016/j.jpba.2020.113851] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/07/2020] [Accepted: 12/14/2020] [Indexed: 12/30/2022]
Abstract
Pregnane X receptor (PXR) is highly expressed in the liver and plays an integral role in the control of xenobiotic and endobiotic metabolism to maintain homeostasis. We previously reported that activation of PXR significantly induced liver enlargement. But the lipid profiling during PXR-induced hepatomegaly remains unclear. This study aimed to characterize the effect of PXR activation on hepatic lipid homeostasis by lipidomics analysis. Mice were intraperitoneally administered with the typical mPXR agonist, pregnenolone 16α-carbonitrile (PCN, 100 mg/kg/d), for 5 days. Liver and serum were collected for further analysis. The results confirmed that PXR activation can significantly induce liver enlargement. An obvious hepatic lipid accumulation was observed in PCN-treated mice, as determined by H&E and Oil Red O staining. Ultra-high performance liquid chromatography-Q Exactive Orbitrap high-resolution mass spectrometer (UHPLC-Q Exactive Orbitrap HRMS)-based lipidomics was performed to characterize the change in lipid species. A total of 20 potential lipid biomarkers were significantly perturbed. The most significant change was found in the triacylglycerol (TG), which constituted with the lower number of carbon atoms and double bonds. Moreover, the mRNA expression levels showed that PCN-induced PXR activation significantly regulated the expression of genes involved in the uptake, synthesis and metabolism of TG, which was consistent with increased TG levels. Collectively, these findings demonstrated that lipids such as TG were significantly accumulated during PXR-induced hepatomegaly.
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Lonardo A, Leoni S, Alswat KA, Fouad Y. History of Nonalcoholic Fatty Liver Disease. Int J Mol Sci 2020; 21:E5888. [PMID: 32824337 PMCID: PMC7460697 DOI: 10.3390/ijms21165888] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/10/2020] [Accepted: 08/12/2020] [Indexed: 12/15/2022] Open
Abstract
Based on the assumption that characterizing the history of a disease will help in improving practice while offering a clue to research, this article aims at reviewing the history of nonalcoholic fatty liver disease (NAFLD) in adults and children. To this end, we address the history of NAFLD histopathology, which begins in 1980 with Ludwig's seminal studies, although previous studies date back to the 19th century. Moreover, the principal milestones in the definition of genetic NAFLD are summarized. Next, a specific account is given of the evolution, over time, of our understanding of the association of NAFLD with metabolic syndrome, spanning from the outdated concept of "NAFLD as a manifestation of the Metabolic Syndrome", to the more appropriate consideration that NAFLD has, with metabolic syndrome, a mutual and bi-directional relationship. In addition, we also report on the evolution from first intuitions to more recent studies, supporting NAFLD as an independent risk factor for cardiovascular disease. This association probably has deep roots, going back to ancient Middle Eastern cultures, wherein the liver had a significance similar to that which the heart holds in contemporary society. Conversely, the notions that NAFLD is a forerunner of hepatocellular carcinoma and extra-hepatic cancers is definitely more modern. Interestingly, guidelines issued by hepatological societies have lagged behind the identification of NAFLD by decades. A comparative analysis of these documents defines both shared attitudes (e.g., ultrasonography and lifestyle changes as the first approaches) and diverging key points (e.g., the threshold of alcohol consumption, screening methods, optimal non-invasive assessment of liver fibrosis and drug treatment options). Finally, the principal historical steps in the general, cellular and molecular pathogenesis of NAFLD are reviewed. We conclude that an in-depth understanding of the history of the disease permits us to better comprehend the disease itself, as well as to anticipate the lines of development of future NAFLD research.
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Affiliation(s)
- Amedeo Lonardo
- Ospedale Civile di Baggiovara, UOC Medicina Metabolica, Dipartimento di Medicina Interna Generale, d’Urgenza e post Acuzie, Azienda Ospedaliero-Universitaria di Modena, Via Giardini 1135, 41125 Modena, Italy
| | - Simona Leoni
- Internal Medicine Unit, Department of Digestive Diseases, S.Orsola-Malpighi Hospital, Via Massarenti 9, 40136 Bologna, Italy;
| | - Khalid A. Alswat
- Liver Research Center, Department of Medicine, College of Medicine, King Saud University, Riyadh 11322, Saudi Arabia;
| | - Yasser Fouad
- Department of Gastroenterology, Hepatology and Endemic Medicine, Faculty of Medicine, Minia University, Minya 19111, Egypt;
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Lipid Metabolism in Development and Progression of Hepatocellular Carcinoma. Cancers (Basel) 2020; 12:cancers12061419. [PMID: 32486341 PMCID: PMC7352397 DOI: 10.3390/cancers12061419] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 05/19/2020] [Accepted: 05/27/2020] [Indexed: 12/11/2022] Open
Abstract
: Metabolic reprogramming is critically involved in the development and progression of cancer. In particular, lipid metabolism has been investigated as a source of energy, micro-environmental adaptation, and cell signalling in neoplastic cells. However, the specific role of lipid metabolism dysregulation in hepatocellular carcinoma (HCC) has not been widely described yet. Alterations in fatty acid synthesis, β-oxidation, and cellular lipidic composition contribute to initiation and progression of HCC. The aim of this review is to elucidate the mechanisms by which lipid metabolism is involved in hepatocarcinogenesis and tumour adaptation to different conditions, focusing on the transcriptional aberrations with new insights in lipidomics and lipid zonation. This will help detect new putative therapeutic approaches in the second most frequent cause of cancer-related death.
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14
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d'Angelo M, Castelli V, Tupone MG, Catanesi M, Antonosante A, Dominguez-Benot R, Ippoliti R, Cimini AM, Benedetti E. Lifestyle and Food Habits Impact on Chronic Diseases: Roles of PPARs. Int J Mol Sci 2019; 20:ijms20215422. [PMID: 31683535 PMCID: PMC6862628 DOI: 10.3390/ijms20215422] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 02/07/2023] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that exert important functions in mediating the pleiotropic effects of diverse exogenous factors such as physical exercise and food components. Particularly, PPARs act as transcription factors that control the expression of genes implicated in lipid and glucose metabolism, and cellular proliferation and differentiation. In this review, we aim to summarize the recent advancements reported on the effects of lifestyle and food habits on PPAR transcriptional activity in chronic disease.
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Affiliation(s)
- Michele d'Angelo
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
| | - Vanessa Castelli
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
| | - Maria Grazia Tupone
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
| | - Mariano Catanesi
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
| | - Andrea Antonosante
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
| | - Reyes Dominguez-Benot
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
| | - Rodolfo Ippoliti
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
| | - Anna Maria Cimini
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
- Sbarro Institute for Cancer Research and Molecular Medicine and Center for Biotechnology, Temple University, Philadelphia, PA 19122, USA.
| | - Elisabetta Benedetti
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
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15
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Chen K, Zhong J, Hu L, Li R, Du Q, Cai J, Li Y, Gao Y, Cui X, Yang X, Wu X, Yao L, Dai J, Wang Y, Jin H. The Role of Xenobiotic Receptors on Hepatic Glycolipid Metabolism. Curr Drug Metab 2019; 20:29-35. [PMID: 30227815 DOI: 10.2174/1389200219666180918152241] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 03/13/2018] [Accepted: 08/20/2018] [Indexed: 01/14/2023]
Abstract
Background:
PXR (Pregnane X Receptor) and CAR (Constitutive Androstane Receptor) are termed as
xenobiotic receptors, which are known as core factors in regulation of the transcription of metabolic enzymes and
drug transporters. However, accumulating evidence has shown that PXR and CAR exert their effects on energy metabolism
through the regulation of gluconeogenesis, lipogenesis and β-oxidation. Therefore, in this review, we are
trying to summary recent advances to show how xenobiotic receptors regulate energy metabolism.
Methods:
A structured search of databases has been performed by using focused review topics. According to conceptual
framework, the main idea of research literature was summarized and presented.
Results:
For introduction of each receptor, the general introduction and the critical functions in hepatic glucose and
lipid metabolism have been included. Recent important studies have shown that CAR acts as a negative regulator of
lipogenesis, gluconeogenesis and β -oxidation. PXR activation induces lipogenesis, inhibits gluconeogenesis and
inhabits β-oxidation.
Conclusion:
In this review, the importance of xenobiotic receptors in hepatic glucose and lipid metabolism has been
confirmed. Therefore, PXR and CAR may become new therapeutic targets for metabolic syndrome, including obesity
and diabetes. However, further research is required to promote the clinical application of this new energy metabolism
function of xenobiotic receptors.
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Affiliation(s)
- Ke Chen
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jinwei Zhong
- Department of Gastroenterology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Lin Hu
- Pi-wei Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Ruliu Li
- Pi-wei Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Qun Du
- Pi-wei Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jiazhong Cai
- Pi-wei Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yanwu Li
- Pi-wei Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yong Gao
- Pi-wei Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xiaona Cui
- Department of Pathogenic Biology and Immunology, Jiangsu Key Laboratory of Immunity and Metabolism, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Xiaoying Yang
- Department of Pathogenic Biology and Immunology, Jiangsu Key Laboratory of Immunity and Metabolism, Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Xiaojie Wu
- Department of Immunology, Binzhou Medical University, Yantai, Shangdong, China
| | - Lu Yao
- Jilin Medical University, Jilin, China
| | - Juji Dai
- School of Basic Medical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yan Wang
- Department of Otolaryngology, The Second Affiliated Hospital & Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Haiyong Jin
- Department of Otolaryngology, The Second Affiliated Hospital & Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
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16
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Role of gut microbiota in the development of non-alcoholic fatty liver disease. LIVER RESEARCH 2019. [DOI: 10.1016/j.livres.2019.01.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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17
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Metabolic aspects in NAFLD, NASH and hepatocellular carcinoma: the role of PGC1 coactivators. Nat Rev Gastroenterol Hepatol 2019; 16:160-174. [PMID: 30518830 DOI: 10.1038/s41575-018-0089-3] [Citation(s) in RCA: 144] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alterations of hepatic metabolism are critical to the development of liver disease. The peroxisome proliferator-activated receptor-γ coactivators (PGC1s) are able to orchestrate, on a transcriptional level, different aspects of liver metabolism, such as mitochondrial oxidative phosphorylation, gluconeogenesis and fatty acid synthesis. As modifications affecting both mitochondrial and lipid metabolism contribute to the initiation and/or progression of liver steatosis, nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC), a link between disrupted PGC1 pathways and onset of these pathological conditions has been postulated. However, despite the large quantity of studies, the scenario is still not completely understood, and some issues remain controversial. Here, we discuss the roles of PGC1s in healthy liver and explore their contribution to the pathogenesis and future therapy of NASH and HCC.
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18
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Roh YS, Kim JW, Park S, Shon C, Kim S, Eo SK, Kwon JK, Lim CW, Kim B. Toll-Like Receptor-7 Signaling Promotes Nonalcoholic Steatohepatitis by Inhibiting Regulatory T Cells in Mice. THE AMERICAN JOURNAL OF PATHOLOGY 2018; 188:2574-2588. [DOI: 10.1016/j.ajpath.2018.07.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 06/09/2018] [Accepted: 07/10/2018] [Indexed: 12/17/2022]
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19
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Echeverría F, Valenzuela R, Espinosa A, Bustamante A, Álvarez D, Gonzalez-Mañan D, Ortiz M, Soto-Alarcon SA, Videla LA. Reduction of high-fat diet-induced liver proinflammatory state by eicosapentaenoic acid plus hydroxytyrosol supplementation: involvement of resolvins RvE1/2 and RvD1/2. J Nutr Biochem 2018; 63:35-43. [PMID: 30321750 DOI: 10.1016/j.jnutbio.2018.09.012] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/13/2018] [Accepted: 09/12/2018] [Indexed: 02/07/2023]
Abstract
High-fat diet (HFD)-fed mice show obesity with development of liver steatosis and a proinflammatory state without establishing an inflammatory reaction. The aim of this work was to assess the hypothesis that eicosapentaenoic acid (EPA) plus hydroxytyrosol (HT) supplementation prevents the inflammatory reaction through enhancement in the hepatic resolvin content in HFD-fed mice. Male C57BL/6J mice were fed an HFD or a control diet and supplemented with EPA (50 mg/kg/day) and HT (5 mg/kg/day) or their respective vehicles for 12 weeks. Measurements include liver levels of EPA, DHA and palmitate (gas chromatography), liver resolvins and triglyceride (TG) and serum aspartate transaminase (AST) (specific kits) and hepatic and serum inflammatory markers (quantitative polymerase chain reaction and enzyme-linked immunosorbent assay). Compared to CD, HFD induced body weight gain, liver steatosis and TG accumulation, with up-regulation of proinflammatory markers in the absence of histological inflammation or serum AST changes; these results were accompanied by higher hepatic levels of resolvins RvE1, RvE2, RvD1 and RvD2, with decreases in EPA and DHA contents. EPA+HT supplementation in HFD feeding synergistically reduced the steatosis score over individual treatments and increased the hepatic levels of EPA, DHA and resolvins, with attenuation of proinflammatory markers. Lack of progression of HFD-induced proinflammatory state into overt inflammation is associated with resolvin up-regulation, which is further increased by EPA+HT supplementation eliciting steatosis attenuation. These findings point to the importance of combined protocols in hepatoprotection due to the involvement of cross-talk mechanisms, which increase effectiveness and diminish dosages, avoiding undesirable effects.
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Affiliation(s)
- F Echeverría
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - R Valenzuela
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile.
| | - A Espinosa
- Department of Medical Technology, Faculty of Medicine, University of Chile, Santiago, Chile
| | - A Bustamante
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - D Álvarez
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - D Gonzalez-Mañan
- Núcleo de Química y Bioquímica, Facultad de Ciencias, Universidad Mayor, Chile
| | - M Ortiz
- Nutrition and Dietetics School, Faculty of Health Sciences, Catholic University of Maule, Curicó, Chile
| | - S A Soto-Alarcon
- Department of Nutrition, Faculty of Medicine, University of Chile, Santiago, Chile
| | - L A Videla
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile
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20
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Lee YH, Kim SH, Kim SN, Kwon HJ, Kim JD, Oh JY, Jung YS. Sex-specific metabolic interactions between liver and adipose tissue in MCD diet-induced non-alcoholic fatty liver disease. Oncotarget 2018; 7:46959-46971. [PMID: 27409675 PMCID: PMC5216916 DOI: 10.18632/oncotarget.10506] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/30/2016] [Indexed: 02/06/2023] Open
Abstract
Higher susceptibility to metabolic disease in male exemplifies the importance of sexual dimorphism in pathogenesis. We hypothesized that the higher incidence of non-alcoholic fatty liver disease in males involves sex-specific metabolic interactions between liver and adipose tissue. In the present study, we used a methionine-choline deficient (MCD) diet-induced fatty liver mouse model to investigate sex differences in the metabolic response of the liver and adipose tissue. After 2 weeks on an MCD-diet, fatty liver was induced in a sex-specific manner, affecting male mice more severely than females. The MCD-diet increased lipolytic enzymes in the gonadal white adipose tissue (gWAT) of male mice, whereas it increased expression of uncoupling protein 1 and other brown adipocyte markers in the gWAT of female mice. Moreover, gWAT from female mice demonstrated higher levels of oxygen consumption and mitochondrial content compared to gWAT from male mice. FGF21 expression was increased in liver tissue by the MCD diet, and the degree of upregulation was significantly higher in the livers of female mice. The endocrine effect of FGF21 was responsible, in part, for the sex-specific browning of gonadal white adipose tissue. Collectively, these data demonstrated that distinctively female-specific browning of white adipose tissue aids in protecting female mice against MCD diet-induced fatty liver disease.
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Affiliation(s)
- Yun-Hee Lee
- College of Pharmacy, Yonsei University, Incheon, Republic of Korea
| | - Sou Hyun Kim
- College of Pharmacy, Pusan National University, Busan, Republic of Korea
| | - Sang-Nam Kim
- College of Pharmacy, Yonsei University, Incheon, Republic of Korea
| | - Hyun-Jung Kwon
- College of Pharmacy, Yonsei University, Incheon, Republic of Korea
| | - Jeong-Dong Kim
- College of Pharmacy, Yonsei University, Incheon, Republic of Korea
| | - Ji Youn Oh
- College of Pharmacy, Pusan National University, Busan, Republic of Korea
| | - Young-Suk Jung
- College of Pharmacy, Pusan National University, Busan, Republic of Korea
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21
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Izdebska M, Piątkowska-Chmiel I, Korolczuk A, Herbet M, Gawrońska-Grzywacz M, Gieroba R, Sysa M, Czajkowska-Bania K, Cygal M, Korga A, Dudka J. The beneficial effects of resveratrol on steatosis and mitochondrial oxidative stress in HepG2 cells. Can J Physiol Pharmacol 2017; 95:1442-1453. [DOI: 10.1139/cjpp-2016-0561] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is currently one of the most common chronic liver diseases, especially in developed countries. One group of substances with a potential use in the treatment of NAFLD are plant polyphenols, represented by resveratrol. The aim of this study was to evaluate the effect of resveratrol on steatosis and oxidative stress in HepG2 cells. The steatosis of cells was carried out using free fatty acids: oleic or palmitic acid and their mixtures. Steatosis was visualized using the intracellular lipid staining by Nile Red dye with a fluorescence microscope. This study also determined the viability of cells and mitochondrial membrane potential. The current study showed that fatty acids and their mixtures induced fat overloading in HepG2 cells. In the group of cells incubated with oleic acid (OA), observed changes were moderate with prevailing micro-vesicular steatosis. In case of cells incubated with palmitic acid (PA) and the mixtures of fatty acids, micro- and macro-vacuolar steatosis occurred in most of the cells. Resveratrol decreased steatosis in HepG2 cells induced by OA, PA, as well as their mixtures, and in most of experimental groups did not reduce cells viability. Resveratrol reduced the oxidative stress in HepG2 cells treated with fatty acids mixtures.
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Affiliation(s)
- Magdalena Izdebska
- Department of Toxicology, Medical University of Lublin, Chodzki 8, Lublin 20-093, Poland
| | | | - Agnieszka Korolczuk
- Department of Clinical Pathomorphology, Medical University of Lublin, Jaczewskiego 8b, Lublin 20-090, Poland
| | - Mariola Herbet
- Department of Toxicology, Medical University of Lublin, Chodzki 8, Lublin 20-093, Poland
| | | | - Renata Gieroba
- Medical Biology Unit, Medical University of Lublin, Jaczewskiego 8b, Lublin 20-090, Poland
| | - Marcin Sysa
- Department of Toxicology, Medical University of Lublin, Chodzki 8, Lublin 20-093, Poland
| | | | - Marcelina Cygal
- Department of Toxicology, Medical University of Lublin, Chodzki 8, Lublin 20-093, Poland
| | - Agnieszka Korga
- Department of Toxicology, Medical University of Lublin, Chodzki 8, Lublin 20-093, Poland
| | - Jarosław Dudka
- Department of Toxicology, Medical University of Lublin, Chodzki 8, Lublin 20-093, Poland
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22
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Ranjan A, Ansari SA. Therapeutic potential of Mediator complex subunits in metabolic diseases. Biochimie 2017; 144:41-49. [PMID: 29061530 DOI: 10.1016/j.biochi.2017.10.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/16/2017] [Indexed: 01/16/2023]
Abstract
The multisubunit Mediator is an evolutionary conserved transcriptional coregulatory complex in eukaryotes. It is needed for the transcriptional regulation of gene expression in general as well as in a gene specific manner. Mediator complex subunits interact with different transcription factors as well as components of RNA Pol II transcription initiation complex and in doing so act as a bridge between gene specific transcription factors and general Pol II transcription machinery. Specific interaction of various Mediator subunits with nuclear receptors (NRs) and other transcription factors involved in metabolism has been reported in different studies. Evidences indicate that ligand-activated NRs recruit Mediator complex for RNA Pol II-dependent gene transcription. These NRs have been explored as therapeutic targets in different metabolic diseases; however, they show side-effects as targets due to their overlapping involvement in different signaling pathways. Here we discuss the interaction of various Mediator subunits with transcription factors involved in metabolism and whether specific interaction of these transcription factors with Mediator subunits could be potentially utilized as therapeutic strategy in a variety of metabolic diseases.
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Affiliation(s)
- Amol Ranjan
- Stowers Institute for Medical Research, 1000 E, 50th Street, Kansas City, MO, 64110, USA
| | - Suraiya A Ansari
- Department of Biochemistry, College of Medicine and Health Sciences, UAE University, AlAin, Abu Dhabi, United Arab Emirates.
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23
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24
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Buzzetti E, Pinzani M, Tsochatzis EA. The multiple-hit pathogenesis of non-alcoholic fatty liver disease (NAFLD). Metabolism 2016; 65:1038-48. [PMID: 26823198 DOI: 10.1016/j.metabol.2015.12.012] [Citation(s) in RCA: 1829] [Impact Index Per Article: 228.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 11/14/2015] [Accepted: 12/17/2015] [Indexed: 02/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent and represents a growing challenge in terms of prevention and treatment. Despite its high prevalence, only a small minority of affected patients develops inflammation and subsequently fibrosis and chronic liver disease, while most of them only exhibit simple steatosis. In this context, the full understanding of the mechanisms underlying the development of NAFLD and non-alcoholic steatohepatitis (NASH) is of extreme importance; despite advances in this field, knowledge on the pathogenesis of NAFLD is still incomplete. The 'two-hit' hypothesis is now obsolete, as it is inadequate to explain the several molecular and metabolic changes that take place in NAFLD. The "multiple hit" hypothesis considers multiple insults acting together on genetically predisposed subjects to induce NAFLD and provides a more accurate explanation of NAFLD pathogenesis. Such hits include insulin resistance, hormones secreted from the adipose tissue, nutritional factors, gut microbiota and genetic and epigenetic factors. In this article, we review the factors that form this hypothesis.
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Affiliation(s)
- Elena Buzzetti
- UCL Institute for Liver and Digestive Health and Sheila Sherlock Liver Unit, Royal Free Hospital and UCL, London, UK
| | - Massimo Pinzani
- UCL Institute for Liver and Digestive Health and Sheila Sherlock Liver Unit, Royal Free Hospital and UCL, London, UK
| | - Emmanuel A Tsochatzis
- UCL Institute for Liver and Digestive Health and Sheila Sherlock Liver Unit, Royal Free Hospital and UCL, London, UK.
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25
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Hakkola J, Rysä J, Hukkanen J. Regulation of hepatic energy metabolism by the nuclear receptor PXR. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1072-1082. [PMID: 27041449 DOI: 10.1016/j.bbagrm.2016.03.012] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 12/30/2022]
Abstract
The pregnane X receptor (PXR) is a nuclear receptor that is traditionally thought to be specialized for sensing xenobiotic exposure. In concurrence with this feature PXR was originally identified to regulate drug-metabolizing enzymes and transporters. During the last ten years it has become clear that PXR harbors broader functions. Evidence obtained both in experimental animals and humans indicate that ligand-activated PXR regulates hepatic glucose and lipid metabolism and affects whole body metabolic homeostasis. Currently, the consequences of PXR activation on overall metabolic health are not yet fully understood and varying results on the effect of PXR activation or knockout on metabolic disorders and weight gain have been published in mouse models. Rifampicin and St. John's wort, the prototypical human PXR agonists, impair glucose tolerance in healthy volunteers. Chronic exposure to PXR agonists could potentially represent a risk factor for diabetes and metabolic syndrome. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie.
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Affiliation(s)
- Jukka Hakkola
- Research Unit of Biomedicine, Pharmacology and Toxicology, University of Oulu, Oulu, Finland; Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.
| | - Jaana Rysä
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Janne Hukkanen
- Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland; Research Unit of Internal Medicine, University of Oulu, Oulu, Finland; Department of Internal Medicine, Oulu University Hospital, Oulu, Finland; Biocenter Oulu, Oulu, Finland
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26
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Ballestri S, Nascimbeni F, Romagnoli D, Baldelli E, Lonardo A. The Role of Nuclear Receptors in the Pathophysiology, Natural Course, and Drug Treatment of NAFLD in Humans. Adv Ther 2016; 33:291-319. [PMID: 26921205 DOI: 10.1007/s12325-016-0306-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Indexed: 02/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) describes steatosis, nonalcoholic steatohepatitis with or without fibrosis, and hepatocellular carcinoma, namely the entire alcohol-like spectrum of liver disease though observed in the nonalcoholic, dysmetabolic, individual free of competing causes of liver disease. NAFLD, which is a major public health issue, exhibits intrahepatic triglyceride storage giving rise to lipotoxicity. Nuclear receptors (NRs) are transcriptional factors which, activated by ligands, are master regulators of metabolism and also have intricate connections with circadian control accounting for cyclical patterns in the metabolic fate of nutrients. Several transcription factors, such as peroxisome proliferator-activated receptors, liver X receptors, farnesoid X receptors, and their molecular cascades, finely regulate energetic fluxes and metabolic pathways. Dysregulation of such pathways is heavily implicated in those metabolic derangements characterizing insulin resistance and metabolic syndrome and in the histogenesis of progressive NAFLD forms. We review the role of selected NRs in NAFLD pathogenesis. Secondly, we analyze the role of NRs in the natural history of human NAFLD. Next, we discuss the results observed in humans following administration of drug agonists or antagonists of the NRs pathogenically involved in NAFLD. Finally, general principles of treatment and lines of research in human NAFLD are briefly examined.
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Affiliation(s)
| | - Fabio Nascimbeni
- NOCSAE, Outpatient Liver Clinic and Operating Unit Internal Medicine, Azienda USL Modena, Modena, Italy
- University of Modena and Reggio Emilia, Modena, Italy
| | - Dante Romagnoli
- NOCSAE, Outpatient Liver Clinic and Operating Unit Internal Medicine, Azienda USL Modena, Modena, Italy
| | | | - Amedeo Lonardo
- NOCSAE, Outpatient Liver Clinic and Operating Unit Internal Medicine, Azienda USL Modena, Modena, Italy.
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27
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Bitter A, Rümmele P, Klein K, Kandel BA, Rieger JK, Nüssler AK, Zanger UM, Trauner M, Schwab M, Burk O. Pregnane X receptor activation and silencing promote steatosis of human hepatic cells by distinct lipogenic mechanisms. Arch Toxicol 2014; 89:2089-103. [PMID: 25182422 DOI: 10.1007/s00204-014-1348-x] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 08/25/2014] [Indexed: 12/20/2022]
Abstract
In addition to its well-characterized role in the regulation of drug metabolism and transport by xenobiotics, pregnane X receptor (PXR) critically impacts on lipid homeostasis. In mice, both ligand-dependent activation and knockout of PXR were previously shown to promote hepatic steatosis. To elucidate the respective pathways in human liver, we generated clones of human hepatoma HepG2 cells exhibiting different PXR protein levels, and analyzed effects of PXR activation and knockdown on steatosis and expression of lipogenic genes. Ligand-dependent activation as well as knockdown of PXR resulted in increased steatosis in HepG2 cells. Activation of PXR induced the sterol regulatory element-binding protein (SREBP) 1-dependent lipogenic pathway via PXR-dependent induction of SREBP1a, which was confirmed in primary human hepatocytes. Inhibiting SREBP1 activity by blocking the cleavage-dependent maturation of SREBP1 protein impaired the induction of lipogenic SREBP1 target genes and triglyceride accumulation by PXR activation. On the other hand, PXR knockdown resulted in up-regulation of aldo-keto reductase (AKR) 1B10, which enhanced the acetyl-CoA carboxylase (ACC)-catalyzed reaction step of de novo lipogenesis. In a cohort of human liver samples histologically classified for non-alcoholic fatty liver disease, AKR1B10, SREBP1a and SREBP1 lipogenic target genes proved to be up-regulated in steatohepatitis, while PXR protein was reduced. In summary, our data suggest that activation and knockdown of PXR in human hepatic cells promote de novo lipogenesis and steatosis by induction of the SREBP1 pathway and AKR1B10-mediated increase of ACC activity, respectively, thus providing mechanistic explanations for a putative dual role of PXR in the pathogenesis of steatohepatitis.
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Affiliation(s)
- Andreas Bitter
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
| | - Petra Rümmele
- Institute of Pathology, University of Regensburg, Regensburg, Germany
| | - Kathrin Klein
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
| | - Benjamin A Kandel
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
| | - Jessica K Rieger
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
| | - Andreas K Nüssler
- Department of Traumatology, University of Tübingen, Tübingen, Germany
| | - Ulrich M Zanger
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
| | - Michael Trauner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Matthias Schwab
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany
- Department of Clinical Pharmacology, Institute of Experimental and Clinical Pharmacology and Toxicology, University Hospital, Tübingen, Germany
| | - Oliver Burk
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, 70376, Stuttgart, Germany.
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Mahmoud AM. Hesperidin protects against cyclophosphamide-induced hepatotoxicity by upregulation of PPARγ and abrogation of oxidative stress and inflammation. Can J Physiol Pharmacol 2014; 92:717-24. [DOI: 10.1139/cjpp-2014-0204] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The most important reason for the non-approval and withdrawal of drugs by the Food and Drug Administration is hepatotoxicity. Therefore, this study was undertaken to evaluate the protective effects of hesperidin against cyclophosphamide (CYP)-induced hepatotoxicity in Wistar rats. The rats received a single intraperitoneal dose of CYP of 200 mg/kg body mass, followed by treatment with hesperidin, orally, at doses of 25 and 50 mg/kg for 11 consecutive days. CYP induced hepatic damage, as evidenced by the significantly elevated levels of serum pro-inflammatory cytokines, serum transaminases, liver lipid peroxidation, and nitric oxide. As a consequence, there was reduced glutathione content, and the activities of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase, were markedly reduced. In addition, CYP administration induced a considerable downregulation of peroxisome proliferator activated receptor gamma (PPARγ) and upregulation of nuclear factor-kappa B (NF-κB) and inducible nitric oxide synthase (iNOS) mRNA expression. Hesperidin, in a dose-dependent manner, rejuvenated the altered markers to an almost normal state. In conclusion, hesperidin showed a potent protective effect against CYP-induced oxidative stress and inflammation leading to hepatotoxicity. The study suggests that hesperidin exerts its protective effect against CYP-induced hepatotoxicity through upregulation of hepatic PPARγ expression and abrogation of inflammation and oxidative stress.
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Affiliation(s)
- Ayman M. Mahmoud
- Physiology Division, Zoology Department, Faculty of Science, Beni-Suef University, 62514 Beni-Suef, Egypt
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29
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Rogue A, Anthérieu S, Vluggens A, Umbdenstock T, Claude N, de la Moureyre-Spire C, Weaver RJ, Guillouzo A. PPAR agonists reduce steatosis in oleic acid-overloaded HepaRG cells. Toxicol Appl Pharmacol 2014; 276:73-81. [PMID: 24534255 DOI: 10.1016/j.taap.2014.02.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 12/04/2013] [Accepted: 02/06/2014] [Indexed: 12/19/2022]
Abstract
UNLABELLED Although non-alcoholic fatty liver disease (NAFLD) is currently the most common form of chronic liver disease there is no pharmacological agent approved for its treatment. Since peroxisome proliferator-activated receptors (PPARs) are closely associated with hepatic lipid metabolism, they seem to play important roles in NAFLD. However, the effects of PPAR agonists on steatosis that is a common pathology associated with NAFLD, remain largely controversial. In this study, the effects of various PPAR agonists, i.e. fenofibrate, bezafibrate, troglitazone, rosiglitazone, muraglitazar and tesaglitazar on oleic acid-induced steatotic HepaRG cells were investigated after a single 24-hour or 2-week repeat treatment. Lipid vesicles stained by Oil-Red O and triglycerides accumulation caused by oleic acid overload, were decreased, by up to 50%, while fatty acid oxidation was induced after 2-week co-treatment with PPAR agonists. The greatest effects on reduction of steatosis were obtained with the dual PPARα/γ agonist muraglitazar. Such improvement of steatosis was associated with up-regulation of genes related to fatty acid oxidation activity and down-regulation of many genes involved in lipogenesis. Moreover, modulation of expression of some nuclear receptor genes, such as FXR, LXRα and CAR, which are potent actors in the control of lipogenesis, was observed and might explain repression of de novo lipogenesis. CONCLUSION Altogether, our in vitro data on steatotic HepaRG cells treated with PPAR agonists correlated well with clinical investigations, bringing a proof of concept that drug-induced reversal of steatosis in human can be evaluated in in vitro before conducting long-term and costly in vivo studies in animals and patients.
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Affiliation(s)
- Alexandra Rogue
- Inserm UMR 991, 35043 Rennes Cedex, France; Université de Rennes 1, Faculté des Sciences Pharmaceutiques et Biologiques, 35043 Rennes Cedex, France; Biologie Servier, Gidy, France
| | - Sébastien Anthérieu
- Inserm UMR 991, 35043 Rennes Cedex, France; Université de Rennes 1, Faculté des Sciences Pharmaceutiques et Biologiques, 35043 Rennes Cedex, France
| | - Aurore Vluggens
- Inserm UMR 991, 35043 Rennes Cedex, France; Université de Rennes 1, Faculté des Sciences Pharmaceutiques et Biologiques, 35043 Rennes Cedex, France
| | | | - Nancy Claude
- Institut de Recherches Servier, Courbevoie, France
| | | | | | - André Guillouzo
- Inserm UMR 991, 35043 Rennes Cedex, France; Université de Rennes 1, Faculté des Sciences Pharmaceutiques et Biologiques, 35043 Rennes Cedex, France.
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30
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Spruiell K, Richardson RM, Cullen JM, Awumey EM, Gonzalez FJ, Gyamfi MA. Role of pregnane X receptor in obesity and glucose homeostasis in male mice. J Biol Chem 2013; 289:3244-61. [PMID: 24362030 DOI: 10.1074/jbc.m113.494575] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Clinical obesity is a complex metabolic disorder affecting one in three adults. Recent reports suggest that pregnane X receptor (PXR), a xenobiotic nuclear receptor important for defense against toxic agents and for eliminating drugs and other xenobiotics, may be involved in obesity. Noting differences in ligand specificities between human and mouse PXRs, the role of PXR in high fat diet (HFD)-induced obesity was examined using male PXR-humanized (hPXR) transgenic and PXR-knock-out (PXR-KO) mice in comparison to wild-type (WT) mice. After 16 weeks on either a control diet or HFD, WT mice showed greater weight gain, whereas PXR-KO mice gained less weight due to their resistance to HFD-induced decreases in adipose tissue peroxisome proliferator-activated receptor α and induction of hepatic carnitine palmitoyltransferase 1, suggesting increased energy metabolism. Interestingly, control-fed PXR-KO mice exhibited hepatomegaly, hyperinsulinemia, and hyperleptinemia but hypoadiponectinemia and lower adiponectin receptor R2 mRNA levels relative to WT mice. Evaluation of these biologic indicators in hPXR mice fed a control diet or HFD revealed further differences between the mouse and human receptors. Importantly, although HFD-fed hPXR mice were resistant to HFD-induced obesity, both PXR-KO and hPXR mice exhibited impaired induction of glucokinase involved in glucose utilization and displayed elevated fasting glucose levels and severely impaired glucose tolerance. Moreover, the basal hepatic levels of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase 1 were increased in hPXR mice compared with WT mice. Altogether, although the mouse PXR promotes HFD-induced obesity, the hPXR mouse carries a genetic predisposition for type 2 diabetes and thus provides a model for exploring the role of human PXR in the metabolic syndrome.
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Affiliation(s)
- Krisstonia Spruiell
- From the Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina 27707
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Clostridium butyricum MIYAIRI 588 improves high-fat diet-induced non-alcoholic fatty liver disease in rats. Dig Dis Sci 2013; 58:3534-44. [PMID: 24166662 DOI: 10.1007/s10620-013-2879-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 09/05/2013] [Indexed: 12/16/2022]
Abstract
BACKGROUND/AIMS Non-alcoholic fatty liver disease (NAFLD) has become a common liver disease, as its prevalence has increased markedly in recent decades. The aim of the present study was to examine the improving effect of Clostridium butyricum MIYAIRI 588 (CBM588), a probiotic in clinical use for antibiotic-associated diarrhea, against high-fat diet (HFD)-induced fatty liver in rats. METHODS After feeding HFD or HFD coated with CBM588 (HFD-CBM) for 12 weeks, we evaluated the hepatic mRNA levels related to lipid metabolism, and then assessed the hepatic protein levels of several transcription factors regulating these lipogenic gene expressions. RESULTS The HFD-CBM group had decreased accumulation of lipid droplets in the liver compared with the HFD group. The HFD-CBM group had significantly decreased diacylglycerol acyltransferase (DGAT) 2 mRNA in the liver compared with the HFD group, whereas DGAT1 mRNA did not change between the HFD group and the HFD-CBM group. Moreover, the HFD-CBM group had significantly increased hepatic mRNA regulating cholesterol catabolism enzymes and excretion transporters. Correspondingly, the HFD-CBM588 groups had increased hepatic protein levels of peroxisome proliferator-activated receptor α/γ and liver X receptor α compared with the HFD group. The HFD-CBM group had accelerated excretion of total bile acid and non-esterified fatty acid in the feces. CONCLUSIONS CBM588 intake may have novel potential for improving NAFLD.
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Carulli L, Ballestri S, Lonardo A, Lami F, Violi E, Losi L, Bonilauri L, Verrone AM, Odoardi MR, Scaglioni F, Bertolotti M, Loria P. Is nonalcoholic steatohepatitis associated with a high-though-normal thyroid stimulating hormone level and lower cholesterol levels? Intern Emerg Med 2013; 8:297-305. [PMID: 21559749 DOI: 10.1007/s11739-011-0609-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 04/21/2011] [Indexed: 02/06/2023]
Abstract
Hypothyroidism is associated with the risk of development of the metabolic syndrome (MS) and hypercholesterolemia. Direct evidence that hypothyroidism might be associated with advanced chronic liver disease via nonalcoholic steatohepatitis (NASH) is limited. We studied the relationship between thyroid hormones, thyroid stimulating hormone (TSH), cholesterol, and NASH. In consecutive euthyroid patients with biopsy-proven nonalcoholic fatty liver disease, TSH and thyroid hormone (FT3 and FT4) concentrations were compared in 25 patients with steatosis and 44 non-cirrhotic NASH patients featuring concurrent ballooning, lobular inflammation and steatosis. The MS was diagnosed according to ATP III criteria. A meta-analysis of previously published studies was performed to evaluate whether NASH, compared to simple steatosis, is associated with lower cholesterol levels. At univariate analysis, compared to those with steatosis, patients with NASH have a wider waist, elevated levels of BMI, ALT, AST, fasting insulin, HOMA-IR, ferritin, TSH and a lower serum cholesterol. At stepwise multivariable logistic regression analysis, the independent predictors of NASH are high HOMA and TSH and lower total cholesterol (Model 1); MS and high TSH (Model 2). At meta-analysis, serum total cholesterol levels are significantly lower in predominantly non-cirrhotic NASH than in simple steatosis. This study provides cross-sectional and meta-analytic evidence that, in euthyroid patients, high-though-normal TSH values are independently associated with NASH. Further work is needed to ascertain the role, if any, of lower cholesterol serum levels in assisting in the diagnosis of NASH.
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Affiliation(s)
- Lucia Carulli
- Department of Internal Medicine, Endocrinology, Metabolism and Geriatrics, Unit of Internal Medicine, University of Modena and Reggio Emilia, Nuovo Ospedale Civile Sant'Agostino Estense, Via Giardini 1355, 41100, Modena, Italy
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Videla LA, Pettinelli P. Misregulation of PPAR Functioning and Its Pathogenic Consequences Associated with Nonalcoholic Fatty Liver Disease in Human Obesity. PPAR Res 2012; 2012:107434. [PMID: 23304111 PMCID: PMC3526338 DOI: 10.1155/2012/107434] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 11/06/2012] [Indexed: 12/22/2022] Open
Abstract
Nonalcoholic fatty liver disease in human obesity is characterized by the multifactorial nature of the underlying pathogenic mechanisms, which include misregulation of PPARs signaling. Liver PPAR-α downregulation with parallel PPAR-γ and SREBP-1c up-regulation may trigger major metabolic disturbances between de novo lipogenesis and fatty acid oxidation favouring the former, in association with the onset of steatosis in obesity-induced oxidative stress and related long-chain polyunsaturated fatty acid n-3 (LCPUFA n-3) depletion, insulin resistance, hypoadiponectinemia, and endoplasmic reticulum stress. Considering that antisteatotic strategies targeting PPAR-α revealed that fibrates have poor effectiveness, thiazolidinediones have weight gain limitations, and dual PPAR-α/γ agonists have safety concerns, supplementation with LCPUFA n-3 appears as a promising alternative, which achieves both significant reduction in liver steatosis scores and a positive anti-inflammatory outcome. This latter aspect is of importance as PPAR-α downregulation associated with LCPUFA n-3 depletion may play a role in increasing the DNA binding capacity of proinflammatory factors, NF-κB and AP-1, thus constituting one of the major mechanisms for the progression of steatosis to steatohepatitis.
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Affiliation(s)
- Luis A. Videla
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Casilla 70000, Santiago 7, Chile
| | - Paulina Pettinelli
- Ciencias de la Salud, Nutrición y Dietética, Facultad de Medicina, Pontificia Universidad Católica de Chile, 7820436 Santiago, Chile
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35
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Valenzuela R, Videla LA. The importance of the long-chain polyunsaturated fatty acid n-6/n-3 ratio in development of non-alcoholic fatty liver associated with obesity. Food Funct 2011; 2:644-8. [PMID: 22008843 DOI: 10.1039/c1fo10133a] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most important cause of chronic liver disease that is characterized by hepatocyte triacylglycerol accumulation (steatosis), which can progress to inflammation, fibrosis, and cirrhosis (steatohepatitis). Overnutrition triggers the onset of oxidative stress in the liver due to higher availability and oxidation of fatty acids (FA), with development of hyperinsulinemia and insulin resistance (IR), and n-3 long-chain polyunsaturated FA (n-3 LCPUFA) depletion, with enhancement in the n-6/n-3 LCPUFA ratio favouring a pro-inflammatory state. These changes may lead to hepatic steatosis by different mechanisms, namely, (i) IR-dependent higher peripheral lipolysis and FA flux to the liver, (ii) n-3 LCPUFA depletion-induced changes in DNA binding activity of sterol regulatory element-binding protein 1c (SREBP-1c) and peroxisome proliferator-activated receptor α (PPAR-α) favouring lipogenesis over FA oxidation, and (iii) hyperinsulinemia-induced activation of lipogenic factor PPAR-γ. Supplementation with n-3 LCPUFA appears to reduce nutritional hepatic steatosis in adults, however, other histopathologic features of NAFLD remain to be studied.
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Affiliation(s)
- Rodrigo Valenzuela
- School of Nutrition and Dietetics, Faculty of Medicine, Santiago-7, Chile
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Ai ZL, Zhu CH, Min M, Wang J, Lan CH, Fan LL, Sun WJ, Chen DF. The Role of Hepatic Liver X Receptor α-and Sterol Regulatory Element Binding Protein-1c-Mediated Lipid Disorder in the Pathogenesis of Non-Alcoholic Steatohepatitis in Rats. J Int Med Res 2011; 39:1219-29. [PMID: 21986124 DOI: 10.1177/147323001103900410] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Liver X receptor α (LXRα) and sterol regulatory element binding protein-1c (SREBP-1c) were studied in rats with non-alcoholic steatohepatitis (NASH) induced by a high-fat diet. Forty 5-week-old rats were fed either a high-fat diet ( n = 30) or a normal diet ( n = 10) for 9, 13 or 17 weeks. The mRNA and protein levels for LXRα and SREBP-1c were measured at each time point, as was fatty acid synthase (FAS) activity and the serum levels of free fatty acid (FFA) and triglyceride (TG). The mRNA and protein levels for LXRα and SREBP-1c, FAS activity and serum levels of FFA and TG all significantly increased from week 9 in the high-fat diet rats versus controls. In conclusion, a high-fat diet upregulates LXRα which, in turn, upregulates SREBP-1c, increasing the activity of FAS and FFA and accumulation of TG in hepatocytes. Thus, LXRα and SREBP-1c contribute to the development of NASH.
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Affiliation(s)
- Z-L Ai
- Department of Gastroenterology and Hepatology, Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
| | - C-H Zhu
- Department of Gastroenterology and Hepatology, Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
- Department of Gastroenterology and Hepatology, Hospital 309 of the People's Liberation Army, Beijing, China
| | - M Min
- Department of Gastroenterology and Hepatology, Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
| | - J Wang
- Department of Gastroenterology and Hepatology, Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
| | - C-H Lan
- Department of Gastroenterology and Hepatology, Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
| | - L-L Fan
- Department of Gastroenterology and Hepatology, Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
| | - W-J Sun
- Department of Gastroenterology and Hepatology, Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
| | - D-F Chen
- Department of Gastroenterology and Hepatology, Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
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Videla LA, Obregón AM, Pettinelli P. Patología de hígado graso no-alcohólico (HGNA) asociada a obesidad: mecanismos patogénicos. Medwave 2011. [DOI: 10.5867/medwave.2011.07.5068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Pettinelli P, Videla LA. Up-regulation of PPAR-gamma mRNA expression in the liver of obese patients: an additional reinforcing lipogenic mechanism to SREBP-1c induction. J Clin Endocrinol Metab 2011; 96:1424-30. [PMID: 21325464 DOI: 10.1210/jc.2010-2129] [Citation(s) in RCA: 248] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
INTRODUCTION Triglyceride accumulation in the liver is an early feature in the development of nonalcoholic fatty liver disease (NAFLD) associated with human obesity, which is a multifactorial syndrome and whose underlying mechanisms are beginning to be understood. OBJECTIVES Liver peroxisome proliferator-activated receptor-γ (PPAR-γ) mRNA expression was measured as a signaling mechanism related to steatosis in obese patients with NAFLD. METHODS Liver PPAR-γ and sterol receptor element-binding protein 1c (SREBP-1c) mRNA (real-time RT-PCR), serum total adiponectin (RIA), and high molecular weight (HMW)-adiponectin (ELISA) levels, and insulin resistance (IR) evolution (homeostasis model assessment-IR) were determined in 22 obese NAFLD patients (16 with steatosis and six with steatohepatitis) who underwent subtotal gastrectomy with gastrojejunal anastomosis in Roux-en-Y and 16 nonobese subjects who underwent laparoscopic cholecystectomy (controls). RESULTS Liver PPAR-γ mRNA levels were 112 and 188% higher (P < 0.05) than control values in obese patients with steatosis and steatohepatitis, respectively, who also exhibited 70 and 62% increases in those of SREBP-1c, concomitantly with IR and lower levels of serum total adiponectin and HMW-adiponectin (P < 0.05). Liver PPAR-γ expression showed positive associations with SREBP-1c mRNA levels (r = 0.86; P < 0.0001), serum insulin levels (r = 0.39; P < 0.01), and homeostasis model assessment-IR (r = 0.60; P < 0.0001), and negative correlations with total adiponectin (r = -0.37; P < 0.01) and HMW-adiponectin (r = -0.51; P < 0.001) levels in serum. CONCLUSIONS PPAR-γ is up-regulated in the liver of obese patients with NAFLD, representing an additional reinforcing lipogenic mechanism to SREBP-1c induction in the development of hepatic steatosis.
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Affiliation(s)
- Paulina Pettinelli
- Department of Food Science, Nutrition, and Dietetics, Faculty of Pharmacy, University of Concepción, Casilla 237, Concepción, Chile.
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Mizrahi M, Lalazar G, Adar T, Raz I, Ilan Y. Assessment of insulin resistance by a 13C glucose breath test: a new tool for early diagnosis and follow-up of high-risk patients. Nutr J 2010; 9:25. [PMID: 20507559 PMCID: PMC2890689 DOI: 10.1186/1475-2891-9-25] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 05/27/2010] [Indexed: 01/08/2023] Open
Abstract
Background/Aims Insulin resistance (IR) plays an important role in the pathogenesis of diabetes and non-alcoholic fatty liver disease (NAFLD). Current methods for insulin resistance detection are cumbersome, or not sensitive enough for early detection and follow-up. The BreathID® system can continuously analyse breath samples in real-time at the point-of-care. Here we determined the efficacy of the BreathID® using the 13C-Glucose breath test (GBT) for evaluation of insulin resistance. Methods Twenty healthy volunteers were orally administered 75 mg of 13C-glucose 1-13C. An oral glucose tolerance test (OGTT) was performed immediately; followed by serum glucose and insulin level determinations using GBT. GBT and OGTT were repeated following exercise, which alters insulin resistance levels. Results Within-subject correlations of GBT parameters with serum glucose and serum insulin levels were high. Before and after exercise, between-subjects correlations were high between the relative insulin levels and the % dose recoveries at 90 min (PDR 90), and the cumulative PDRs at 60 min (CPDR 60). Pairwise correlations were identified between pre-exercise Homeostasis Model Assessment (HOMA) IR at 90 min and PDR 90; HOMA B (for beta cell function) 120 and CPDR 30; HOMA IR 60 and peak time post-exercise; and HOMA B 150 with PDR 150. Conclusions The non-invasive real-time BreathID® GBT reliably assesses changes in liver glucose metabolism, and the degree of insulin resistance. It may serve as a non-invasive tool for early diagnosis and follow up of patients in high-risk groups.
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Affiliation(s)
- Meir Mizrahi
- Department of Medicine, Liver Unit, Hebrew University-Hadassah Medical Center Ein Karem, Jerusalem 12000, Israel
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40
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Videla LA. Liver NF-κB and AP-1 activation and PPAR-α expression are negatively correlated in obese patients: pro-inflammatory implications. Clin Nutr 2010; 29:687-8. [PMID: 20403650 DOI: 10.1016/j.clnu.2010.03.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 03/02/2010] [Accepted: 03/16/2010] [Indexed: 11/27/2022]
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Martín-Castillo A, Castells MT, Adánez G, Polo MTS, Pérez BG, Ayala I. Effect of atorvastatin and diet on non-alcoholic fatty liver disease activity score in hyperlipidemic chickens. Biomed Pharmacother 2010; 64:275-81. [DOI: 10.1016/j.biopha.2009.06.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Accepted: 06/07/2009] [Indexed: 01/07/2023] Open
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Hijona E, Hijona L, Arenas JI, Bujanda L. Inflammatory mediators of hepatic steatosis. Mediators Inflamm 2010; 2010:837419. [PMID: 20300479 PMCID: PMC2840375 DOI: 10.1155/2010/837419] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Revised: 01/10/2010] [Accepted: 02/10/2010] [Indexed: 12/12/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming a world-wide public health problem. NAFLD represents a spectrum of disease ranging from "simple steatosis", which is considered relatively benign, to nonalcoholic steatohepatitis and to NAFLD-associated cirrhosis and end-stage liver disease. The etiology of NAFLD and its progression is complex and remains incompletely understood. The progression of the disease involves many factors. Apart from the two hits, the accumulation of TG and the development of fibrosis and necroinflammatory processes, exit numerous molecules associated with these two hits. Among them we can highlight the pro-inflammatory molecules and adiponectins. This review focuses on the growing evidence from both experimental and human studies suggesting a central role of cytokines in the pathogenesis of NAFLD. We review the role of cytokines as key regulators of insulin sensitivity and hepatic lipid overloading, liver injury and inflammation, and fibrosis with an emphasis on potential therapeutic implications.
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Affiliation(s)
- Elizabeth Hijona
- Gastroenterology Department, Donostia Hospital, CIBERehd, University of the Basque Country, 20010 San Sebastián, Spain
| | - Lander Hijona
- Gastroenterology Department, Basurto Hospital, 48013 Bilbao, Spain
| | - Juan I. Arenas
- Gastroenterology Department, Donostia Hospital, CIBERehd, University of the Basque Country, 20010 San Sebastián, Spain
| | - Luis Bujanda
- Gastroenterology Department, Donostia Hospital, CIBERehd, University of the Basque Country, 20010 San Sebastián, Spain
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Arrese M, Karpen SJ. Nuclear receptors, inflammation, and liver disease: insights for cholestatic and fatty liver diseases. Clin Pharmacol Ther 2010; 87:473-8. [PMID: 20200515 DOI: 10.1038/clpt.2010.2] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Members of the nuclear receptor (NR) superfamily of ligand-activated transcription factors are players of substantial relevance in the regulation of hepatic gene expression. NRs direct normal physiology and metabolism, adaptations to liver disease, and responses to inflammation and toxins.They also contribute to the regenerative response. In this review, we summarize currently available experimental and clinical data, focusing on the role of NRs in cholestasis and nonalcoholic fatty liver disease (NAFLD). We also highlight the potential of NRs as targets for safe and effective therapeutic interventions.
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Affiliation(s)
- M Arrese
- Department of Gastroenterology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
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Enhanced steatosis by nuclear receptor ligands: a study in cultured human hepatocytes and hepatoma cells with a characterized nuclear receptor expression profile. Chem Biol Interact 2010; 184:376-87. [PMID: 20079722 DOI: 10.1016/j.cbi.2010.01.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Revised: 12/15/2009] [Accepted: 01/05/2010] [Indexed: 12/21/2022]
Abstract
Steatosis is the first step in the development of non-alcoholic fatty liver disease (NAFLD). However, the mechanisms involved in its pathogenesis are not fully understood. Many nuclear receptors (NRs) involved in energy homeostasis and biotransformation constitute a network connecting fatty acids, cholesterol and xenobiotic metabolisms; therefore, multiple NRs and their ligands may play a prominent role in liver fat metabolism and accumulation. In this study we have attempted to gain insight into the relevance of the NR superfamily in NAFLD by investigating the steatogenic potential of 76 different NR ligands in fatty acid overloaded human hepatocytes and hepatoma cells. Moreover, we have determined the mRNA expression level of 24 NRs to correlate the steatogenic potential of the ligands with the expression of their associated NRs in the cultured cells. Our results demonstrate that 18% of the examined NR ligands enhanced lipid accumulation in human hepatocytes and/or hepatoma cells. Among them, ligands of PPARgamma (e.g., thiazolidinediones), LXR (paxilline and 24(S),25-epoxycholesterol), PXR (hyperforin), CAR (3alpha,5alpha-androstenol), ERalpha (tamoxifen), FXR (Z-guggulsterone), VDR (25-hydroxyvitamin D3) and particular retinoids and farnesoids showed a significant pro-steatotic effect. The mRNA level of most of the NRs examined was well preserved in human hepatocytes, but HepG2 showed a deranged profile, where many of the receptors had a marginal or negligible level of expression in comparison with the human liver. By comparing the steatogenic effect of NR ligands with the NR expression levels, we conclude that LXR, PXR, RAR and PPARgamma ligands likely induce fat accumulation by a NR-dependent mechanism. Indeed, over-expression of PXR in HepG2 cells enhanced the steatogenic effect of hyperforin and rifampicin. However, the accumulation of fat induced by other ligands did not correlate with the expression of their associated NR. Our results also suggest that human hepatocytes cultured with free fatty acids offer a highly valuable in vitro system to investigate the pathogenesis and therapeutics of the human fatty liver.
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Trauner M, Arrese M, Wagner M. Fatty liver and lipotoxicity. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:299-310. [PMID: 19857603 DOI: 10.1016/j.bbalip.2009.10.007] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 10/15/2009] [Accepted: 10/15/2009] [Indexed: 02/08/2023]
Abstract
Fatty liver disease comprises a spectrum ranging from simple steatosis to steatohepatitis which can progress to liver cirrhosis and hepatocellular cancer. Hepatic lipotoxicity may ensue when the hepatic capacity to utilize, store and export fatty acids (FA) as triglycerides is overwhelmed. Additional mechanisms of hepatic lipotoxicity include abnormal FA oxidation with formation of reactive oxygen species, disturbances in cellular membrane FA and phospholipid composition, alterations of cholesterol content and ceramide signalling. Lipotoxicity is a key factor for the progression of fatty liver disease by inducing hepatocellular death, activating Kupffer cells and an inflammatory response, impairing hepatic insulin signalling resulting in insulin resistance, and activation of a fibrogenic response in hepatic stellate cells that can ultimately lead to cirrhosis. Therefore, the concept of hepatic lipotoxicity should be considered in future therapeutic concepts for fatty liver disease.
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Affiliation(s)
- Michael Trauner
- Laboratory of Experimental and Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria.
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Grattagliano I, Bonfrate L, Diogo CV, Wang HH, Wang DQH, Portincasa P. Biochemical mechanisms in drug-induced liver injury: Certainties and doubts. World J Gastroenterol 2009; 15:4865-76. [PMID: 19842215 PMCID: PMC2764962 DOI: 10.3748/wjg.15.4865] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Drug-induced liver injury is a significant and still unresolved clinical problem. Limitations to knowledge about the mechanisms of toxicity render incomplete the detection of hepatotoxic potential during preclinical development. Several xenobiotics are lipophilic substances and their transformation into hydrophilic compounds by the cytochrome P-450 system results in production of toxic metabolites. Aging, preexisting liver disease, enzyme induction or inhibition, genetic variances, local O2 supply and, above all, the intrinsic molecular properties of the drug may affect this process. Necrotic death follows antioxidant consumption and oxidation of intracellular proteins, which determine increased permeability of mitochondrial membranes, loss of potential, decreased ATP synthesis, inhibition of Ca2+-dependent ATPase, reduced capability to sequester Ca2+ within mitochondria, and membrane bleb formation. Conversely, activation of nucleases and energetic participation of mitochondria are the main intracellular mechanisms that lead to apoptosis. Non-parenchymal hepatic cells are inducers of hepatocellular injury and targets for damage. Activation of the immune system promotes idiosyncratic reactions that result in hepatic necrosis or cholestasis, in which different HLA genotypes might play a major role. This review focuses on current knowledge of the mechanisms of drug-induced liver injury and recent advances on newly discovered mechanisms of liver damage. Future perspectives including new frontiers for research are discussed.
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Cipriani S, Mencarelli A, Palladino G, Fiorucci S. FXR activation reverses insulin resistance and lipid abnormalities and protects against liver steatosis in Zucker (fa/fa) obese rats. J Lipid Res 2009; 51:771-84. [PMID: 19783811 DOI: 10.1194/jlr.m001602] [Citation(s) in RCA: 332] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The farnesoid X receptor (FXR) is a bile acid activated nuclear receptor. Zucker (fa/fa) rats, harboring a loss of function mutation of the leptin receptor, develop diabetes, insulin resistance, obesity, and liver steatosis. In this study, we investigated the effect of FXR activation by 6-ethyl-chenodeoxycholic acid, (6E-CDCA, 10 mg/kg) on insulin resistance and liver and muscle lipid metabolism in fa/fa rats and compared its activity with rosiglitazone (10 mg/kg) alone or in combination with 6E-CDCA (5 mg/kg each). In comparison to lean (fa/+), fa/fa rats on a normal diet developed insulin resistance and liver steatosis. FXR activation protected against body weight gain and liver and muscle fat deposition and reversed insulin resistance as assessed by insulin responsive substrate-1 phosphorylation on serine 312 in liver and muscles. Activation of FXR reduced liver expression of genes involved in fatty acid synthesis, lipogenesis, and gluconeogenesis. In the muscles, FXR treatment reduced free fatty acid synthesis. Rosiglitazone reduced blood insulin, glucose, triglyceride, free fatty acid, and cholesterol plasma levels but promoted body weight gain (20%) and liver fat deposition. FXR activation reduced high density lipoprotein plasma levels. In summary, FXR administration reversed insulin resistance and correct lipid metabolism abnormalities in an obesity animal model.
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Affiliation(s)
- Sabrina Cipriani
- Dipartimento di Medicina Clinica e Sperimentale, Università di Perugia, Via E. dal Pozzo, Perugia, Italy
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Pettinelli P, Del Pozo T, Araya J, Rodrigo R, Araya AV, Smok G, Csendes A, Gutierrez L, Rojas J, Korn O, Maluenda F, Diaz JC, Rencoret G, Braghetto I, Castillo J, Poniachik J, Videla LA. Enhancement in liver SREBP-1c/PPAR-alpha ratio and steatosis in obese patients: correlations with insulin resistance and n-3 long-chain polyunsaturated fatty acid depletion. Biochim Biophys Acta Mol Basis Dis 2009; 1792:1080-6. [PMID: 19733654 DOI: 10.1016/j.bbadis.2009.08.015] [Citation(s) in RCA: 175] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 08/26/2009] [Accepted: 08/31/2009] [Indexed: 12/13/2022]
Abstract
Sterol receptor element-binding protein-1c (SREBP-1c) and peroxisome proliferator-activated receptor-alpha (PPAR-alpha) mRNA expression was assessed in liver as signaling mechanisms associated with steatosis in obese patients. Liver SREBP-1c and PPAR-alpha mRNA (RT-PCR), fatty acid synthase (FAS) and carnitine palmitoyltransferase-1a (CPT-1a) mRNA (real-time RT-PCR), and n-3 long-chain polyunsaturated fatty acid (LCPUFA)(GLC) contents, plasma adiponectin levels (RIA), and insulin resistance (IR) evolution (HOMA) were evaluated in 11 obese patients who underwent subtotal gastrectomy with gastro-jejunal anastomosis in Roux-en-Y and 8 non-obese subjects who underwent laparoscopic cholecystectomy (controls). Liver SREBP-1c and FAS mRNA levels were 33% and 70% higher than control values (P<0.05), respectively, whereas those of PPAR-alpha and CPT-1a were 16% and 65% lower (P<0.05), respectively, with a significant 62% enhancement in the SREBP-1c/PPAR-alpha ratio. Liver n-3 LCPUFA levels were 53% lower in obese patients who also showed IR and hipoadiponectinemia over controls (P<0.05). IR negatively correlated with both the hepatic content of n-3 LCPUFA (r=-0.55; P<0.01) and the plasma levels of adiponectin (r=-0.62; P<0.005). Liver SREBP-1c/PPAR-alpha ratio and n-3 LCPUFA showed a negative correlation (r=-0.48; P<0.02) and positive associations with either HOMA (r=0.75; P<0.0001) or serum insulin levels (r=0.69; P<0.001). In conclusion, liver up-regulation of SREBP-1c and down-regulation of PPAR-alpha occur in obese patients, with enhancement in the SREBP-1c/PPAR-alpha ratio associated with n-3 LCPUFA depletion and IR, a condition that may favor lipogenesis over FA oxidation thereby leading to steatosis.
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Affiliation(s)
- Paulina Pettinelli
- Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile
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Regulation of bile acid and cholesterol metabolism by PPARs. PPAR Res 2009; 2009:501739. [PMID: 19636418 PMCID: PMC2712638 DOI: 10.1155/2009/501739] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 05/15/2009] [Indexed: 01/27/2023] Open
Abstract
Bile acids are amphipathic molecules synthesized from cholesterol in the liver. Bile acid synthesis is a major pathway for hepatic cholesterol catabolism. Bile acid synthesis generates bile flow which is important for biliary secretion of free cholesterol, endogenous metabolites, and xenobiotics. Bile acids are biological detergents that facilitate intestinal absorption of lipids and fat-soluble vitamins. Recent studies suggest that bile acids are important metabolic regulators of lipid, glucose, and energy homeostasis. Agonists of peroxisome proliferator-activated receptors (PPARα, PPARγ, PPARδ) regulate lipoprotein metabolism, fatty acid oxidation, glucose homeostasis and inflammation, and therefore are
used as anti-diabetic drugs for treatment of dyslipidemia and insulin insistence. Recent studies have shown that activation of
PPARα alters bile acid synthesis, conjugation, and transport, and also cholesterol synthesis, absorption and reverse cholesterol transport. This review will focus on the roles of PPARs in the regulation of pathways in bile acid and cholesterol homeostasis, and the therapeutic implications of using PPAR agonists for the treatment of metabolic syndrome.
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