NAFLD: The role of genetics

Transcription

1 NAFLD: The role of genetics Luca Valenti Department of Pathophysiology and Transplantation, Università degli Studi di Milano Internal Medicine, Fondazione IRCCS Ca Granda Ospedale Maggiore Policlinico Riunione Monotematica AISF Ottobre 2016

2 Dr. Luca Valenti, Prof. Ass., Università di Milano Il sottoscritto dichiara di non aver avuto/di aver avuto negli ultimi 12 mesi conflitto d interesse in relazione a questa presentazione e che la presentazione non contiene/contiene discussione di farmaci in studio o ad uso off-label

3 Histological spectrum of NAFLD: From simple steatosis to NASH and HCC Steatosis Ballooning Lobular inflammation Peri-cellular/venular fibrosis Cirrhosis HCC

4 Liver histology in 351 consecutive severely obese individuals Normal liver 14% NASH & Significant fibrosis 11.5% Simple steatosis 31.5% NASH w/o Significant fibrosis 31%

5 Fatty liver % Prevalence of steatosis varies with ethnicity Dallas Heart Study 45% 42% 24% 24% M F M F M F Hispanics Whites Blacks Browning, Hepatology 2004

6 Co-inheritance of metabolic traits, hepatic fat and fibrosis Cui, Hepatology 2016

7 Hepatic Fat (%) BMI (kg/m 2 ) HOMA-IR Plasma TG (mg/dl) GWAS in NAFLD led to identification of PNPLA3 I148M Speliotes Kitamoto Chambers 6 p = 7 x NCAN LYPAL1 PPP1R3B 40 GCKR Romeo PNPLA3 rs C>G 4 TRIB1 100 CPN1 HSD17B13 II 4 PATATIN-LIKE PHOSPHOLIPASE DOMAIN-CONTAINING 3 (PNPLA3) 30 GASAG I148M DGGV 20 3 Anstee IM MM PNPLA3 rs C>G (I148M) 0 always confirmed top hit with larger effect size 25

8 Obesity and insulin resistance favor lipid droplets accumulation in hepatocytes Obesity Insulin resistance Lipid droplets HFC: 0-5% Extracellular space FFAs PNPLA3 148I TM6SF2 167E Tg Nascent VLDL VLDL secretion Endoplasmic Reticulum Early Golgi Dongiovanni, BMC Research International, 2015

9 Impaired lipid droplets remodeling causes NASH in PNPLA3 I148M carriers Obesity Insulin resistance PNPLA3 148M Extracellular space HFC: 6% FFAs Lipid droplets TM6SF2 167E Tg Nascent VLDL VLDL secretion Endoplasmic Reticulum Early Golgi Romeo, Nat Genet 2008, He, J Biol Chem 2010; Ruhanen, J Lipid Res 2014; Dongiovanni, World J Gastroentorol 2013; Dongiovanni, Hepatology 2014; Donati, Hepatology 2015

10 The NASH score

11 PNPLA3 I148M and fibrosis risk in patients with NAFLD Sookoian, Hepatology 2011

12 The spectrum of NAFLD Prevalence: PNPLA3 148M/M: HCC Cirrhosis > NASH Simple steatosis 0.10 Healthy 0.05

13 PNPLA3 has retynil-esterase activity in HSCs and the I148M variant is a loss of function Retinyl-palmitate PNPLA3 148M Palmitic acid Retinol MMP2 TIMP1 TIMP2 Inihibition of lipogenesis Regeneration Differentiation

14 PNPLA3 I148M and progressive liver disease: a new paradigm in hepatology Alcohol Fructose Obesity and insulin resistance Hepatitis C virus PNPLA3 148I PNPLA3 148M Mild uncomplicated steatosis Direct carcinogenic activity Steatohepatitis & fibrogenesis PNPLA3 148M/M Cirrhosis Hepatocellular carcinoma Valenti, Hepatology 2012 Valenti, Dig Liver Dis 2013

15 TM6SF2 is involved in lipidation of VLDL and secretion of lipids from hepatocytes Obesity Insulin resistance Lipid droplets HFC: 0-5% Extracellular space FFAs PNPLA3 148I TM6SF2 167E Tg Nascent VLDL VLDL secretion Endoplasmic Reticulum Early Golgi Dongiovanni, BMC Research International, 2015; Smagris, J Biol Chem 2016

16 Impaired VLDL secretion in E167K TM6SF2 carriers causes NASH Obesity Insulin resistance Lipid droplets Extracellular space FFAs PNPLA3 148I HFC: 6% TM6SF2 167K Nascent VLDL VLDL secretion Endoplasmic Reticulum Early Golgi Kozlitina, Nat Genet 2014; Holmen, Nat Genet 2014; Mahdessian, PNAS 2014; Dongiovanni, Hepatology 2014

17 Prevalence % TM6SF2 E167K variant disentangles NASH from cardiovascular disease p=0.003 p=0.008 p=0.031 E167K TM6SF2 EE n = 1,044 EK + KK n = NASH Advanced fibrosis Carotid plaques

18 Hyperglycemia Hyperinsulinemia Obesity Insulin resistance Lipotoxicity FFAR4 IL28B MERTK? IRS1 ENPP1 FABP5 GCKR KLF6 TRIB1 Lipid droplets MBOAT7 LYPLAL1 PNPLA3 Mitochondria UCP2 SOD2 Fatty acids TM6SF2 MTTP APOB Nascent VLDL Extracellular space VLDL secretion Endoplasmic Reticulum Early Golgi

19 GCKR variants in NAFLD Obesity & Increased intake of sugars and carbohydrates Glucose GCKR 446L Glucokinase Fructose -6-P GCKR 446P Glucokinase Malonyl-CoA Malonyl-CoA CPT-1 Fatty acids oxidation De novo lipogenesis Suppressed De novo lipogenesis Steatosis Increased VLDL secretion Speliotes, PLoS Genet 2011; Valenti, Hepatology 2012; Petta PONE 2014

20 H e p a tic T G c o n te n t (% ) N A S H p re v a le n c e (% ) MBOAT7 rs C>T associates with hepatic fat content and NASH features CC CT TT P=.005 (IQR 2-8) P= (IQR 2-6) (IQR 2-7) N = N =

21 MBOAT7 is involved in phosphatidyl-inositol remodeling within Lands Cycle Thimerosal PI PS PE PC MBOAT7 MBOAT5 Lands Cycle cpla 2 α Arachidonoyl-CoA Hydrolase Co-A Arachidonic Acid Lyso-PI Lyso-PS Lyso-PE Lyso-PC Fatty Acids Ligase Leukotrienes

22 M B O A T 7 p ro te in le v e ls is o fo rm s (A U ) rs C>T down-regulates MBOAT7 M B O A T 7 m R N A le v e ls (A U ) N = P =.03 P <.005 CC CT TT kda CC CT TT 52kDa 44 kda 38 kda MBOAT7 Isoforms 1, 2, CC CT TT β-actin 0.0 C C C T T T N = 7 7 7

23 The predictors of fatty liver from birth to adulthood Valenti & Romeo, J Hepatol 2016

24 The number of PNPLA3, TM6SF2 and MBOAT7 risk variants is associated with NAFLD-HCC HCC frequency (%), SE unadjusted OR 1.56, 95% c.i ; p<0.001 adjusted OR 1.68, 95% c.i ; p< N of at risk alleles HCC (%) Prevalence (%) Adjusted for age, sex, obesity, T2DM, advanced fibrosis (F3-F4)

25 Rare MTTP and APOB mutations compromising VLDL and chylomicrons lipidation/secretion associate with familial progressive NAFLD despite low fat mass Di Filippo, J Hepatol 2014

26 htert mutations in NAFLD-HCC Ala67Val Pro193Leu N-terminal template binding Reverse transcriptase C-terminal Glu113Argfs*79 Glu668Asp Protein domain Exon Polyphen-2 SIFT Provean Ala67Val TEN 1 Benign Tolerated Neutral Glu113Argfs*79 TEN 2 Damaging Damaging Damaging Pro193Leu TEN 2 Benign Tolerated Neutral Glu668Asp RT 5 Probably damaging Damaging Neutral

27 Key points : NAFLD is a strongly heritable disease PNPLA3 I148M variant is the major common genetic risk factor, which predisposes to the full spectrum of NAFLD-related damage Variants in TM6SF2, GCKR, and MBOAT7 influencing hepatocellular lipid handling contribute to the risk Rare genetic mutations with a strong impact on gene function may be involved in predisposition towards advanced disease in specific families

28 EPIDEMIC Exome Sequencing for the Identification of Inherited Mutations Involved in Hepatocellular Carcinoma in NAFLD Fondazione Ca Granda IRCCS - INGM Molecular Medicine Grant 2015/6 My First AIRC Grant 2016/8 n

29 Acknowledgements Metabolic Liver Diseases Lab INGM Raffaele Defrancesco Cristina Cheroni Torino Elisabetta Bugianesi Ester Vanni Udine Giorgio Soardo Pathology Valentina Vaira Marco Maggioni Silvano Bosari Paola Dongiovanni Raffaela Rametta Benedetta Donati Alessandro Pietrelli Marica Meroni Oscar Borsani Guido Baselli Surgery Stefano Gatti Enrico Mozzi Roma Valerio Nobili Luca Miele, Anna Alisi Monza Alberto Piperno Migliavacca Center Massimo Colombo Alessio Aghemo Pietro Lampertico Palermo Salvo Petta Zurich/Dresden Felix Stickel Jochen Hampe Clinical center Silvia Fargion Anna Fracanzani Serena Pelusi Vittorio Borroni Cristina Bertelli Erika Fatta Giuseppina Pisano Marianna Porzio Rosa Lombardi Verona Domenico Girelli Gothenburg Stefano Romeo Dallas Julia Kozlitina Newcastle Quentin Anstee Helen Reeves Chris Day New York Domenico Accili Utpal Pajvani

30 Thank you for your attention!