Understanding Fatty Liver Disease and ...

OUTLINE FATTY LIVER DISEASE FIGHTING THE FATTY LIVER WATCH AN ANIMATION AT: GO.NATURE.COM/2FSDBGT Increased levels of obesity are driving an epidemic of non-alcoholic fatty liver disease. Understanding, diagnosing and treating this progressive condition are now priorities. By Liam Drew; illustration by Lucy Reading-Ikkanda From heart Blood enters To heart CALORIES NOT ALCOHOL Blood exits through hepatic veins to inferior vena cava through hepatic artery An advanced stage of non-alcoholic fatty liver disease (NAFLD) was first described in 1980, confirming that liver disease characterized by an accumulation of fat can develop in people who do not consume excess alcohol'. Associated with obesity and type 2 diabetes, NAFLD is set to become the Diaphragm most common cause of serious liver disease in many nations. Liver HEALTHY LIVER The liver carries out many tasks, including processing nutrients absorbed from the gut, and controlling the levels of glucose, fat and protein in the blood. It stores Неpatocyte Nucleus carbohydrates and a limited amount of fat. Most liver cells are hepatocytes, which can metabolize almost all types of nutrient. A healthy hepatocyte contains a nucleus at its Small droplets of fat From gut Blood carrying fat and nutrients To gut Bile secreted through hepatic ducts into intestines directly or gall bladder for storage centre and evenly distributed droplets of fat. enters through hepatic portal vein REVERSIBLE Bloated hepatocyte 2 NAFLD In NAFLD, hepatocytes accumulate excess fat, a process known as steatosis. Such fat can come from the Displaced nucleus -25% of the Large droplets of fat US population diet, be made in the liver or be released by insulin-resistant fatty (adipose) tissue. have NAFLD2 Fatty liver REVERSIBLE 3 NASH If accumulated fat causes stress and injury to hepatocytes, non-alcoholic steatohepatitis (NASH) develops. Already- bloated hepatocytes swell further and start to die, causing inflammation. Scarring (fibrosis) occurs as collagen fibres replace dead cells. Collagen fibres Up to 30% of people with NAFLD will develop Inflamed, dying hepatocyte NASH? Fatty, inflamed liver IRREVERSIBLE 4 CIRRHOSIS Over the years or decades, dead hepatocytes are broken down and scar tissue accumulates, which stiffens the liver and Up to 20% of people with NASH may go on to develop cirrhosis Scarring impairs its function. Known as cirrhosis, this can lead to liver failure and an increased risk of liver Remnants of Scarred and dead cells shrunken liver cancer. S102 | NATURE | VOL 550 | 12 OCTOBER 2017 © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.