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Warner DR, Liu H, Ghosh Dastidar S, Warner JB, Prodhan MAI, Yin X, Zhang X, Feldstein AE, Gao B, Prough RA, McClain CJ, Kirpich IA. Ethanol and unsaturated dietary fat induce unique patterns of hepatic ω-6 and ω-3 PUFA oxylipins in a mouse model of alcoholic liver disease. PLoS One 2018; 13:e0204119. [PMID: 30256818 PMCID: PMC6157879 DOI: 10.1371/journal.pone.0204119] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 09/04/2018] [Indexed: 12/19/2022] Open
Abstract
Alcoholic liver disease (ALD), a significant health problem, progresses through the course of several pathologies including steatosis, steatohepatitis, fibrosis, and cirrhosis. There are no effective FDA-approved medications to prevent or treat any stages of ALD, and the mechanisms involved in ALD pathogenesis are not well understood. Bioactive lipid metabolites play a crucial role in numerous pathological conditions, as well as in the induction and resolution of inflammation. Herein, a hepatic lipidomic analysis was performed on a mouse model of ALD with the objective of identifying novel metabolic pathways and lipid mediators associated with alcoholic steatohepatitis, which might be potential novel biomarkers and therapeutic targets for the disease. We found that ethanol and dietary unsaturated, but not saturated, fat caused elevated plasma ALT levels, hepatic steatosis and inflammation. These pathologies were associated with increased levels of bioactive lipid metabolites generally involved in pro-inflammatory responses, including 13-hydroxy-octadecadienoic acid, 9,10- and 12,13-dihydroxy-octadecenoic acids, 5-, 8-, 9-, 11-, 15-hydroxy-eicosatetraenoic acids, and 8,9- and 11,12-dihydroxy-eicosatrienoic acids, in parallel with an increase in pro-resolving mediators, such as lipoxin A4, 18-hydroxy-eicosapentaenoic acid, and 10S,17S-dihydroxy-docosahexaenoic acid. Elucidation of alterations in these lipid metabolites may shed new light into the molecular mechanisms underlying ALD development/progression, and be potential novel therapeutic targets.
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Marrero I, Maricic I, Feldstein AE, Loomba R, Schnabl B, Rivera-Nieves J, Eckmann L, Kumar V. Complex Network of NKT Cell Subsets Controls Immune Homeostasis in Liver and Gut. Front Immunol 2018; 9:2082. [PMID: 30254647 PMCID: PMC6141878 DOI: 10.3389/fimmu.2018.02082] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 08/22/2018] [Indexed: 12/23/2022] Open
Abstract
The liver-gut immune axis is enriched in several innate immune cells, including innate-like unconventional and adaptive T cells that are thought to be involved in the maintenance of tolerance to gut-derived antigens and, at the same time, enable effective immunity against microbes. Two subsets of lipid-reactive CD1d-restricted natural killer T (NKT) cells, invariant NKT (iNKT) and type II NKT cells present in both mice and humans. NKT cells play an important role in regulation of inflammation in the liver and gut due to their innate-like properties of rapid secretion of a myriad of pro-inflammatory and anti-inflammatory cytokines and their ability to influence other innate cells as well as adaptive T and B cells. Notably, a bi-directional interactive network between NKT cells and gut commensal microbiota plays a crucial role in this process. Here, we briefly review recent studies related to the cross-regulation of both NKT cell subsets and how their interactions with other immune cells and parenchymal cells, including hepatocytes and enterocytes, control inflammatory diseases in the liver, such as alcoholic and non-alcoholic steatohepatitis, as well as inflammation in the gut. Overwhelming experimental data suggest that while iNKT cells are pathogenic, type II NKT cells are protective in the liver. Since CD1d-dependent pathways are highly conserved from mice to humans, a detailed cellular and molecular understanding of these immune regulatory pathways will have major implications for the development of novel therapeutics against inflammatory diseases of liver and gut.
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Schuster S, Johnson CD, Hennebelle M, Holtmann T, Taha AY, Kirpich IA, Eguchi A, Ramsden CE, Papouchado BG, McClain CJ, Feldstein AE. Oxidized linoleic acid metabolites induce liver mitochondrial dysfunction, apoptosis, and NLRP3 activation in mice. J Lipid Res 2018; 59:1597-1609. [PMID: 30084831 DOI: 10.1194/jlr.m083741] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 06/30/2018] [Indexed: 01/03/2023] Open
Abstract
Circulating oxidized linoleic acid (LA) metabolites (OXLAMs) are increased in patients with nonalcoholic steatohepatitis (NASH) and their levels correlate with disease severity. However, the mechanisms by which OXLAMs contribute to NASH development are incompletely understood. We tested the hypothesis that LA or OXLAMs provided directly through the diet are involved in the development of hepatic injury. C57BL/6 mice were fed an isocaloric high-fat diet containing low LA, high LA, or OXLAMs for 8 weeks. The livers of OXLAM-fed mice showed lower triglyceride concentrations, but higher FA oxidation and lipid peroxidation in association with increased oxidative stress. OXLAM-induced mitochondrial dysfunction was associated with reduced Complex I protein and hepatic ATP levels, as well as increased mitochondrial biogenesis and cytoplasmic mitochondrial DNA. Oxidative stress increased thioredoxin-interacting protein (TXNIP) in the liver and stimulated the activation of mitochondrial apoptosis signal-regulating kinase 1 (ASK1) leading to apoptosis. We also found increased levels of NOD-like receptor protein 3 (NLRP3) inflammasome components and Caspase-1 activation in the livers of OXLAM-fed mice. In vitro, OXLAMs induced hepatocyte cell death, which was partly dependent on Caspase-1 activation. This study identified key mechanisms by which dietary OXLAMs contribute to NASH development, including mitochondrial dysfunction, hepatocyte cell death, and NLRP3 inflammasome activation.
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Hsieh S, Leaderer BP, Feldstein AE, Santoro N, McKay LA, Caprio SS, McConnell RS. Traffic-related air pollution associations with cytokeratin-18, a marker of hepatocellular apoptosis, in an overweight and obese paediatric population. Pediatr Obes 2018; 13:342-347. [PMID: 28730729 PMCID: PMC5775922 DOI: 10.1111/ijpo.12228] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 04/13/2017] [Accepted: 05/01/2017] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Traffic-related air pollution causes fatty liver, inflammation and fibrosis in animal models, but there have been few studies in humans. OBJECTIVES To test the hypothesis that traffic-related air pollution causes non-alcoholic fatty liver disease (NAFLD) and increased markers for non-alcoholic steatohepatitis (NASH); and that NAFLD increases liver susceptibility to increased NASH risk. METHODS Data collected prospectively from 74 overweight or obese children were obtained from the Yale Pediatric Obesity Clinic. Traffic-related air pollution was characterized as vehicle traffic volume on major roads within a 1 km residential buffer, and as residential nitrogen dioxide (NO2 ) exposure. Outcomes were hepatic fat fraction (HFF) measured by magnetic resonance imaging, liver enzymes using standard assays and plasma cytokeratin-18 (CK-18) by immunosorbent assays. RESULTS Significant non-linear relationships with air pollution and CK-18 were found. Plasma CK-18 at follow-up increased from approximately 150 U/L to almost 200 U/L as residential traffic volume increased from 220 000 vehicle-km to 330 000 vehicle-km, after adjustment for baseline CK-18, age and gender. Among patients with NAFLD at baseline, CK-18 increased from 140 U/L to 200 U/L (a 1.5 standard deviation increase in CK-18) as NO2 increased from 8 to 10 ppb. CONCLUSIONS Traffic-related air pollution was associated with CK-18. Effects were larger in children with pre-existing NAFLD at study entry.
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Schuster S, Cabrera D, Arrese M, Feldstein AE. Triggering and resolution of inflammation in NASH. Nat Rev Gastroenterol Hepatol 2018; 15:349-364. [PMID: 29740166 DOI: 10.1038/s41575-018-0009-6] [Citation(s) in RCA: 531] [Impact Index Per Article: 88.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nonalcoholic steatohepatitis (NASH) is considered the progressive form of nonalcoholic fatty liver disease (NAFLD) and is characterized by liver steatosis, inflammation, hepatocellular injury and different degrees of fibrosis. A central issue in this field relates to the identification of those factors that trigger inflammation, thus fuelling the transition from nonalcoholic fatty liver to NASH. These triggers of liver inflammation might have their origins outside the liver (such as in adipose tissue or the gut) as well as inside the organ (for instance, lipotoxicity, innate immune responses, cell death pathways, mitochondrial dysfunction and endoplasmic reticulum stress), both of which contribute to NASH development. In this Review, we summarize the currently available information on the key upstream triggers of inflammation in NASH. We further delineate the mechanisms by which liver inflammation is resolved and the implications of a defective pro-resolution process. A better knowledge of these mechanisms should help to design targeted therapies able to halt or reverse disease progression.
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Eguchi A, Feldstein AE. Extracellular vesicles in non-alcoholic and alcoholic fatty liver diseases. LIVER RESEARCH 2018; 2:30-34. [PMID: 30345152 PMCID: PMC6190912 DOI: 10.1016/j.livres.2018.01.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fatty liver diseases, non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD) are the most common causes of chronic liver disease around the world. NAFLD and ALD can progress towards a more severe form of the disease, including as non-alcoholic steatohepatitis (NASH) and alcoholic steatohepatitis (ASH). In both instances central pathogenic events include hepatocyte death, liver inflammation, pathological angiogenesis, and fibrosis, followed by cirrhosis and cancer. Over the last few years, extracellular vesicles (EVs) have been identified as effective cell-to-cell communicators that contain a cell- and stress-specific cargo from the cell of origin and are capable of transferring this cargo to a target or acceptor cell. In this review, we focus on the growing evidence supporting a role for EVs in the pathophysiology of NASH and ASH as well as their potential roles as targets for novel biomarkers for these conditions.
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Wree A, McGeough MD, Inzaugarat ME, Eguchi A, Schuster S, Johnson CD, Peña CA, Geisler LJ, Papouchado BG, Hoffman HM, Feldstein AE. NLRP3 inflammasome driven liver injury and fibrosis: Roles of IL-17 and TNF in mice. Hepatology 2018; 67:736-749. [PMID: 28902427 PMCID: PMC5849484 DOI: 10.1002/hep.29523] [Citation(s) in RCA: 194] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 07/01/2017] [Accepted: 09/08/2017] [Indexed: 12/11/2022]
Abstract
The NLRP3 inflammasome, a caspase-1 activation platform, plays a key role in the modulation of liver inflammation and fibrosis. Here, we tested the hypothesis that interleukin 17 (IL-17) and tumor necrosis factor (TNF) are key cytokines involved in amplifying and perpetuating the liver damage and fibrosis resulting from NLRP3 activation. To address this hypothesis, gain-of-function Nlrp3A350V knock-in mice were bred onto il17a and Tnf knockout backgrounds allowing for constitutive Nlrp3 activation in myeloid derived cells in mice deficient in IL-17 or TNF. Livers of Nlrp3A350V knock-in mice exhibited severe liver inflammatory changes characterized by infiltration with neutrophils, increased expression of chemokine (C-X-C motif) ligand (CXCL) 1 and CXCL2 chemokines, activated inflammatory macrophages, and elevated levels of IL-17 and TNF. Mutants with ablation of il17a signal showed fewer neutrophils when compared to intact Nlrp3A350V mutants, but still significant inflammatory changes when compared to the nonmutant il17a knockout littermates. The severe inflammatory changes associated with mutant Nlrp3 were almost completely rescued by Tnf knockout in association with a marked decrease in circulating IL-1β levels. Intact Nlrp3A350V mutants showed changes in liver fibrosis, as evidenced by morphometric quantitation of Sirius Red staining and increased mRNA levels of profibrotic genes, including connective tissue growth factor and tissue inhibitor of matrix metalloproteinase 1. Il17a lacking mutants exhibited amelioration of the aforementioned fibrosis, whereas Tnf-deficient mutants showed no signs of fibrosis when compared to littermate controls. Conclusion: Our study uncovers key roles for TNF and, to a lesser extent, IL-17 as mediators of liver inflammation and fibrosis induced by constitutive NLRP3 inflammasome activation in myeloid-derived cells. These findings may lead to therapeutic strategies aimed at halting the progression of liver injury and fibrogenesis in various liver pathogeneses driven by NLRP3 activation. (Hepatology 2018;67:736-749).
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Wree A, Inzaugarat ME, Feldstein AE. Transmembrane BAX Inhibitor motif-containing 1, a novel anti-inflammatory approach for nonalcoholic steatohepatitis treatment. Hepatology 2018; 67:438-441. [PMID: 28859227 PMCID: PMC5770148 DOI: 10.1002/hep.29495] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/28/2017] [Accepted: 08/29/2017] [Indexed: 01/28/2023]
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McGeough MD, Wree A, Inzaugarat ME, Haimovich A, Johnson CD, Peña CA, Goldbach-Mansky R, Broderick L, Feldstein AE, Hoffman HM. TNF regulates transcription of NLRP3 inflammasome components and inflammatory molecules in cryopyrinopathies. J Clin Invest 2017; 127:4488-4497. [PMID: 29130929 DOI: 10.1172/jci90699] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 09/21/2017] [Indexed: 01/10/2023] Open
Abstract
The NLRP3 inflammasome is a protein complex responsible for caspase-1-dependent maturation of the proinflammatory cytokines IL-1β and IL-18. Gain-of-function missense mutations in NLRP3 cause the disease spectrum known as the cryopyrin-associated periodic syndromes (CAPS). In this study, we generated Nlrp3-knockin mice on various KO backgrounds including Il1b/Il18-, caspase-1-, caspase-11- (Casp1/11-), and Tnf-deficient strains. The Nlrp3L351P Il1b-/- Il18-/- mutant mice survived and grew normally until adulthood and, at 6 months of age, exhibited marked splenomegaly and leukophilia. Injection of these mice with low-dose LPS resulted in elevated serum TNF levels compared with Nlrp3L351P Casp1/11-/- mice and Il1b-/- Il18-/- littermates. Treatment of Nlrp3A350V mice with the TNF inhibitor etanercept resulted in all pups surviving to adulthood, with normal body and spleen/body weight ratios. Nlrp3A350V Tnf-/- mice showed a similar phenotypic rescue, with marked reductions in serum IL-1β and IL-18, reduced myeloid inflammatory infiltrate in the skin and spleen, and substantial decreases in splenic mRNA expression of both inflammasome components (Nlrp3, Pycard, pro-Casp1) and pro-cytokines (Il1b, Il18). Likewise, we observed a reduction in the expression of both pro-Casp1 and pro-Il1b in cultured Nlrp3A350V Tnf-/- BM-derived DCs. Our data show that TNF is an important transcriptional regulator of NLRP3 inflammasome components in murine inflammasomopathies. Moreover, these results may have therapeutic implications for CAPS patients with partial responses to IL-1-targeted therapies.
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Warner DR, Liu H, Miller ME, Ramsden CE, Gao B, Feldstein AE, Schuster S, McClain CJ, Kirpich IA. Dietary Linoleic Acid and Its Oxidized Metabolites Exacerbate Liver Injury Caused by Ethanol via Induction of Hepatic Proinflammatory Response in Mice. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 187:2232-2245. [PMID: 28923202 DOI: 10.1016/j.ajpath.2017.06.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/18/2017] [Accepted: 06/22/2017] [Indexed: 01/22/2023]
Abstract
Alcoholic liver disease is a major human health problem leading to significant morbidity and mortality in the United States and worldwide. Dietary fat plays an important role in alcoholic liver disease pathogenesis. Herein, we tested the hypothesis that a combination of ethanol and a diet rich in linoleic acid (LA) leads to the increased production of oxidized LA metabolites (OXLAMs), specifically 9- and 13-hydroxyoctadecadienoic acids (HODEs), which contribute to a hepatic proinflammatory response exacerbating liver injury. Mice were fed unsaturated (with a high LA content) or saturated fat diets (USF and SF, respectively) with or without ethanol for 10 days, followed by a single binge of ethanol. Compared to SF+ethanol, mice fed USF+ethanol had elevated plasma alanine transaminase levels, enhanced hepatic steatosis, oxidative stress, and inflammation. Plasma and liver levels of 9- and 13-HODEs were increased in response to USF+ethanol feeding. We demonstrated that primarily 9-HODE, but not 13-HODE, induced the expression of several proinflammatory cytokines in vitro in RAW264.7 macrophages. Finally, deficiency of arachidonate 15-lipoxygenase, a major enzyme involved in LA oxidation and OXLAM production, attenuated liver injury and inflammation caused by USF+ethanol feeding but had no effect on hepatic steatosis. This study demonstrates that OXLAM-mediated induction of a proinflammatory response in macrophages is one of the potential mechanisms underlying the progression from alcohol-induced steatosis to alcoholic steatohepatitis.
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Kirpich IA, Warner DR, Feldstein AE, McClain CJ. S09-2DIETARY LINOLEIC ACID AND ITS OXIDIZED METABOLITES EXACERBATE LIVER INJURY CAUSED BY ETHANOL VIA INDUCTION OF HEPATIC PRO-INFLAMMATORY RESPONSE. Alcohol Alcohol 2017. [DOI: 10.1093/alcalc/agx075.33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Schuster S, Feldstein AE. NASH: Novel therapeutic strategies targeting ASK1 in NASH. Nat Rev Gastroenterol Hepatol 2017; 14:329-330. [PMID: 28377639 DOI: 10.1038/nrgastro.2017.42] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Abstract
Cell death and inflammation are two central elements in the development of liver fibrosis. Inflammasomes are intracellular multiprotein complexes expressed in both hepatocytes and nonparenchymal cells in the liver that are key regulators of inflammation and cell fate. They respond to cellular danger signals by activating caspase 1, releasing the proinflammatory cytokines IL-1β and IL-18, as well as initiating a novel pathway of programmed cell death termed "pyroptosis." These processes can initiate and perpetuate an abnormal wound-healing response with the principle cellular target being the activation of hepatic stellate cells. From the various inflammasomes, the NLRP3 inflammasome has been increasingly implicated in the pathogenesis of chronic inflammatory liver diseases, including nonalcoholic steatohepatitis, a disease process that is soaring and has evolved as a primary cause of liver fibrosis and need for liver transplantation. In this review, the authors highlight the growing evidence for both indirect and direct effects of inflammasomes in triggering liver fibrosis as well as potential novel targets for antifibrotic therapies.
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Mridha AR, Wree A, Robertson AA, Yeh MM, Johnson CD, Van Rooyen DM, Haczeyni F, Teoh NCH, Savard C, Ioannou GN, Masters SL, Schroder K, Cooper MA, Feldstein AE, Farrell GC. NLRP3 inflammasome blockade reduces liver inflammation and fibrosis in experimental NASH in mice. J Hepatol 2017; 66:1037-1046. [PMID: 28167322 PMCID: PMC6536116 DOI: 10.1016/j.jhep.2017.01.022] [Citation(s) in RCA: 714] [Impact Index Per Article: 102.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 01/04/2017] [Accepted: 01/06/2017] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS NOD-like receptor protein 3 (NLRP3) inflammasome activation occurs in Non-alcoholic fatty liver disease (NAFLD). We used the first small molecule NLRP3 inhibitor, MCC950, to test whether inflammasome blockade alters inflammatory recruitment and liver fibrosis in two murine models of steatohepatitis. METHODS We fed foz/foz and wild-type mice an atherogenic diet for 16weeks, gavaged MCC950 or vehicle until 24weeks, then determined NAFLD phenotype. In mice fed an methionine/choline deficient (MCD) diet, we gavaged MCC950 or vehicle for 6weeks and determined the effects on liver fibrosis. RESULTS In vehicle-treated foz/foz mice, hepatic expression of NLRP3, pro-IL-1β, active caspase-1 and IL-1β increased at 24weeks, in association with cholesterol crystal formation and NASH pathology; plasma IL-1β, IL-6, MCP-1, ALT/AST all increased. MCC950 treatment normalized hepatic caspase 1 and IL-1β expression, plasma IL-1β, MCP-1 and IL-6, lowered ALT/AST, and reduced the severity of liver inflammation including designation as NASH pathology, and liver fibrosis. In vitro, cholesterol crystals activated Kupffer cells and macrophages to release IL-1β; MCC950 abolished this, and the associated neutrophil migration. MCD diet-fed mice developed fibrotic steatohepatitis; MCC950 suppressed the increase in hepatic caspase 1 and IL-1β, lowered numbers of macrophages and neutrophils in the liver, and improved liver fibrosis. CONCLUSION MCC950, an NLRP3 selective inhibitor, improved NAFLD pathology and fibrosis in obese diabetic mice. This is potentially attributable to the blockade of cholesterol crystal-mediated NLRP3 activation in myeloid cells. MCC950 reduced liver fibrosis in MCD-fed mice. Targeting NLRP3 is a logical direction in pharmacotherapy of NASH. LAY SUMMARY Fatty liver disease caused by being overweight with diabetes and a high risk of heart attack, termed non-alcoholic steatohepatitis (NASH), is the most common serious liver disease with no current treatment. There could be several causes of inflammation in NASH, but activation of a protein scaffold within cells termed the inflammasome (NLRP3) has been suggested to play a role. Here we show that cholesterol crystals could be one pathway to activate the inflammasome in NASH. We used a drug called MCC950, which has already been shown to block NLRP3 activation, in an attempt to reduce liver injury in NASH. This drug partly reversed liver inflammation, particularly in obese diabetic mice that most closely resembles the human context of NASH. In addition, such dampening of liver inflammation in NASH achieved with MCC950 partly reversed liver scarring, the process that links NASH to the development of cirrhosis.
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Arrese M, Feldstein AE. NASH-RELATED CIRRHOSIS: AN OCCULT LIVER DISEASE BURDEN. Hepatol Commun 2017; 1:84-86. [PMID: 29335681 PMCID: PMC5721433 DOI: 10.1002/hep4.1033] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 03/16/2017] [Indexed: 12/15/2022] Open
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Alkhouri N, Feldstein AE. Treating nonalcoholic steatohepatitis in children: Not a cinch task. Hepatology 2017; 65:1407-1409. [PMID: 28073147 DOI: 10.1002/hep.29043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 12/14/2016] [Accepted: 01/09/2017] [Indexed: 12/19/2022]
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Cannito S, Morello E, Bocca C, Foglia B, Benetti E, Novo E, Chiazza F, Rogazzo M, Fantozzi R, Povero D, Sutti S, Bugianesi E, Feldstein AE, Albano E, Collino M, Parola M. Microvesicles released from fat-laden cells promote activation of hepatocellular NLRP3 inflammasome: A pro-inflammatory link between lipotoxicity and non-alcoholic steatohepatitis. PLoS One 2017; 12:e0172575. [PMID: 28249038 PMCID: PMC5331985 DOI: 10.1371/journal.pone.0172575] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 02/07/2017] [Indexed: 02/06/2023] Open
Abstract
Non-Alcoholic Fatty Liver Disease (NAFLD) is a major form of chronic liver disease in the general population in relation to its high prevalence among overweight/obese individuals and patients with diabetes type II or metabolic syndrome. NAFLD can progress to steatohepatitis (NASH), fibrosis and cirrhosis and end-stage of liver disease but mechanisms involved are still incompletely characterized. Within the mechanisms proposed to mediate the progression of NAFLD, lipotoxicity is believed to play a major role. In the present study we provide data suggesting that microvesicles (MVs) released by fat-laden cells undergoing lipotoxicity can activate NLRP3 inflammasome following internalization by either cells of hepatocellular origin or macrophages. Inflammasome activation involves NF-kB-mediated up-regulation of NLRP3, pro-caspase-1 and pro-Interleukin-1, then inflammasome complex formation and Caspase-1 activation leading finally to an increased release of IL-1β. Since the release of MVs from lipotoxic cells and the activation of NLRP3 inflammasome have been reported to occur in vivo in either clinical or experimental NASH, these data suggest a novel rational link between lipotoxicity and increased inflammatory response.
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Mann JP, Feldstein AE, Nobili V. Update on lipid species and paediatric nonalcoholic fatty liver disease. Curr Opin Clin Nutr Metab Care 2017; 20:110-116. [PMID: 27906700 DOI: 10.1097/mco.0000000000000346] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE OF REVIEW To describe the recent advances in our understanding of fatty acids and lipids in paediatric nonalcoholic fatty liver disease (NAFLD) and their future implications. RECENT FINDINGS Data have been accumulated to suggest that ceramides are the main drivers of hepatic insulin resistance in NAFLD, and inhibition of ceramide synthesis improves histology in mice.Saturated fatty acids formed by de novo lipogenesis generate increased lipotoxicity compared with dietary-derived saturated fatty acids.Hepatic lipogenesis and associated insulin resistance have been found to be influenced by several novel proteins, including E2F1, cyclic AMP response element binding protein transcriptional coactivator 2, Raptor, and eukaryotic initiation factor 6. There are encouraging data from animal models that modulation of these could be therapeutic targets.Human and animal metabolomics and lipidomics data have been used to generate a lipid signature for NAFLD and nonalcoholic steatohepatitis. Serum lipidomics appears to correlate with hepatic lipidomics.Therapeutic trials of polyunsaturated fatty acids in children have had mixed results, with some reductions in noninvasive biomarkers. SUMMARY Multiple new pathways for drug targets have been identified, and use of lipidomics is likely to become a noninvasive method for assessing disease. However, much of the data for paediatric NAFLD are extrapolated from adult or animal studies.
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Eguchi A, Lazaro RG, Wang J, Kim J, Povero D, Willliams B, Ho SB, Stärkel P, Schnabl B, Ohno-Machado L, Tsukamoto H, Feldstein AE. Extracellular vesicles released by hepatocytes from gastric infusion model of alcoholic liver disease contain a MicroRNA barcode that can be detected in blood. Hepatology 2017; 65:475-490. [PMID: 27639178 PMCID: PMC5407075 DOI: 10.1002/hep.28838] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 08/19/2016] [Accepted: 09/05/2016] [Indexed: 12/13/2022]
Abstract
UNLABELLED Extracellular vesicles (EVs) released during cell stress, or demise, can contain a barcode of the cell origin, including specific microRNAs (miRNAs). Here, we tested the hypothesis that during early alcoholic steatohepatitis (ASH) development, hepatocytes (HCs) release EVs with an miRNA signature that can be measured in circulation. A time-course experiment showed that after 2 weeks of intragastric infusion, a time point that results in isolated steatosis, there was no increase of blood EVs. After 4 weeks of infusion, mice developed features of early ASH accompanied by a marked increase in the level of EVs in blood (P < 0.05), as well as in culture media of isolated HCs (P < 0.001) and hepatic macrophages (P < 0.001), with HCs being the predominant source of EVs. The transcriptome analysis of HC-EVs from ASH mice detected differentially expressed miRNAs, including nine significantly up-regulated and four significantly down-regulated miRNAs. Target prediction and pathway analyses of the up-regulated miRNAs identified 121 potential target genes involved in inflammatory and cancer pathways, such as nuclear factor kappa B, EGF, Wnt, and B-cell lymphoma 2. Three miRNAs, let7f, miR-29a, and miR-340, were increased in blood EVs from ASH mice (P < 0.05), but not in blood EVs from three other models of chronic liver injury, including bile duct ligation, nonalcoholic steatohepatitis, and obese mice, as well as EVs released from hepatocytes exposed to ethanol. Blood EV level (P < 0.01) and three miRNAs (P < 0.05) were significantly increased in patients with ambulatory mild ALD as compared to nonalcoholics. CONCLUSION Damaged hepatocytes from ASH mice are a key EV source with a specific miRNA cargo, which are specific for ASH-related liver injury. These findings uncover EVs as a potentially novel diagnostic for ASH. (Hepatology 2017;65:475-490).
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Nobili V, Feldstein AE. Fatty liver in adolescents: Mechanisms, clinical features and therapy. J Hepatol 2016; 65:1258-1260. [PMID: 27742132 DOI: 10.1016/j.jhep.2016.07.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 07/27/2016] [Accepted: 07/29/2016] [Indexed: 01/11/2023]
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Alkhouri N, Feldstein AE. Noninvasive diagnosis of nonalcoholic fatty liver disease: Are we there yet? Metabolism 2016; 65:1087-95. [PMID: 26972222 PMCID: PMC4931968 DOI: 10.1016/j.metabol.2016.01.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 12/22/2015] [Accepted: 01/07/2016] [Indexed: 12/15/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) has rapidly become the most common form of chronic liver disease in the United States affecting approximately 80-100 million Americans. NAFLD includes a spectrum of diseases ranging from nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH) to fibrosis and eventually cirrhosis. Patients with NASH and significant fibrosis on liver biopsy have an increased risk for liver-related morbidity and mortality compared to those with NAFL. Due to the high prevalence of NAFLD and its progressive nature, there has been an urgent need to develop reliable noninvasive tests that can accurately predict the presence of advanced disease without the need for liver biopsy. These tests can be divided into those that predict the presence of NASH and those that predict the presence of fibrosis. In this review, we provide a concise overview of different noninvasive methods for staging the severity of NAFLD.
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Inzaugarat ME, Wree A, Feldstein AE. Hepatocyte mitochondrial DNA released in microparticles and toll-like receptor 9 activation: A link between lipotoxicity and inflammation during nonalcoholic steatohepatitis. Hepatology 2016; 64:669-71. [PMID: 27239763 PMCID: PMC4956555 DOI: 10.1002/hep.28666] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Crespo M, Lappe S, Feldstein AE, Alkhouri N. Similarities and differences between pediatric and adult nonalcoholic fatty liver disease. Metabolism 2016; 65:1161-71. [PMID: 26961580 DOI: 10.1016/j.metabol.2016.01.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 01/15/2016] [Accepted: 01/18/2016] [Indexed: 02/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is highly common and potentially serious in children and adolescents. The term NAFLD refers to a spectrum of diseases ranging from accumulation of fat in the liver (simple steatosis or nonalcoholic fatty liver "NAFL") to the potentially progressive form of nonalcoholic steatohepatitis (NASH) characterized by hepatocyte ballooning, inflammation, and often associated with fibrosis. While large prospective longitudinal studies in pediatric NAFLD are still lacking, growing evidence suggests that children with NAFL are at increased risk for cardiometabolic complications, while those with NASH and advance fibrosis are also at risk for significant liver-related morbidity including cirrhosis and its complications. Pediatric NAFLD shares features of adult NAFLD but also shows many different characteristics in terms of prevalence, histology, diagnosis and management. Translational studies suggest that NAFLD is a highly heritable disease in which genetic variations and environment closely interact to determine the disease phenotype and the progression to the more advanced forms of the disease. Changes in lifestyle, targeting gradual weight reduction, and physical exercise continue to be the mainstay of treatment for NAFLD in children. Recent advances in development of noninvasive diagnostic modalities and the potential for identifying effective pharmacological interventions may result in significant progress in the management of NAFLD in the pediatric population.
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Arrese M, Cabrera D, Kalergis AM, Feldstein AE. Innate Immunity and Inflammation in NAFLD/NASH. Dig Dis Sci 2016; 61:1294-303. [PMID: 26841783 PMCID: PMC4948286 DOI: 10.1007/s10620-016-4049-x] [Citation(s) in RCA: 321] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 01/19/2016] [Indexed: 02/06/2023]
Abstract
Inflammation and hepatocyte injury and death are the hallmarks of nonalcoholic steatohepatitis (NASH), the progressive form of nonalcoholic fatty liver disease (NAFLD), which is a currently burgeoning public health problem. Innate immune activation is a key factor in triggering and amplifying hepatic inflammation in NAFLD/NASH. Thus, identification of the underlying mechanisms by which immune cells in the liver recognize cell damage signals or the presence of pathogens or pathogen-derived factors that activate them is relevant from a therapeutic perspective. In this review, we present new insights into the factors promoting the inflammatory response in NASH including sterile cell death processes resulting from lipotoxicity in hepatocytes as well as into the altered gut-liver axis function, which involves translocation of bacterial products into portal circulation as a result of gut leakiness. We further delineate the key immune cell types involved and how they recognize both damage-associated molecular patterns or pathogen-associated molecular patterns through binding of surface-expressed pattern recognition receptors, which initiate signaling cascades leading to injury amplification. The relevance of modulating these inflammatory signaling pathways as potential novel therapeutic strategies for the treatment of NASH is summarized.
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Eguchi A, De Mollerat Du Jeu X, Johnson CD, Nektaria A, Feldstein AE. Liver Bid suppression for treatment of fibrosis associated with non-alcoholic steatohepatitis. J Hepatol 2016; 64:699-707. [PMID: 26555271 PMCID: PMC4761314 DOI: 10.1016/j.jhep.2015.11.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 10/27/2015] [Accepted: 11/02/2015] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS Liver fibrosis is the most worrisome feature of non-alcoholic steatohepatitis (NASH). Growing evidence supports a link between hepatocyte apoptosis and liver fibrogenesis. Our aim was to determine the therapeutic efficacy and safety of liver Bid, a key pro-apoptotic molecule, suppression using RNA interference (RNAi) for the treatment of fibrosis. METHODS First, we optimized the delivery system for Bid siRNA in mice using ten different stealth RNAi siRNAs and two lipid formulations -Invivofectamine2.0 and a newly developed Invivofectamine3.0 - that have been designed for high efficacy accumulation in the liver, assessed via real-time PCR of Bid mRNA. Next, C57BL/6 mice were placed on a choline-deficient L-amino acid defined (CDAA) diet. After 19weeks of the CDAA diet, a time point that results in severe fibrotic NASH, mice were injected with the selected Bid siRNA-Invivofectamine3.0 biweekly for three weeks. Additionally hepatocyte-specific Bid deficient (Bid(Δhep)) mice were placed on CDAA diet for 20weeks. RESULTS A maximum Bid knockdown was achieved at 1.5mg/kg siRNA with Invivofectamine3.0, whereas it was at 7mg/kg with Invivofectamine2.0. In NASH mice, after 3weeks of treatment, BID protein was reduced to 10% and this was associated with an improvement in liver fibrosis and inflammation associated with a marked reduction in TUNEL positive cells, caspase 3 activation, and a reduction in mitochondrial BAX and BAK. Bid(Δhep) mice showed similar protection from fibrotic changes. CONCLUSION Our data demonstrate that liver Bid suppression by RNAi technology, as well as hepatocyte-specific Bid deficiency, improves liver fibrosis coupled with a reduction of inflammation in experimental NASH. These findings are consistent with existing evidence that hepatocyte apoptosis triggers hepatic stellate cell activation and liver fibrosis and suggest that Bid inhibition may be useful as an antifibrotic NASH therapy.
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