People can develop liver disease even when they are exposed to second-hand tobacco smoke, according to a study.
Scientists at the University of California, Riverside (UCR) have found that exposure to second-hand tobacco smoke can lead to non-alcoholic fatty liver disease (NAFLD), a common disease and rising cause of chronic liver injury wherein fat accumulates in the liver of people who drink little or no alcohol.
For their study, the researchers exposed some mice to second-hand cigarette smoke for a year in the lab, and observed fat build-up in their liver cells, a sign of NAFLD that eventually leads to liver dysfunction.
The researchers focused on two key regulators of lipid (fat) metabolism that are found in many human cells as well: SREBP (sterol regulatory element-binding protein) that stimulates synthesis of fatty acids in the liver, and AMPK (adenosine monophosphate kinase) that turns SREBP on and off.
They found that second-hand smoke exposure inhibits AMPK activity, which, in turn, causes an increase in activity of SREBP.
More active SREBP results in more fatty acids getting synthesized, they say.
The result is NAFLD induced by second-hand smoke, according to the researchers.
"Our study provides compelling experimental evidence in support of tobacco smoke exposure playing a major role in NAFLD development," said Manuela Martins-Green, a professor of cell biology, who led the study.
"Our work points to SREBP and AMPK as new molecular targets for drug therapy that can reverse NAFLD development resulting from second-hand smoke. Drugs could now be developed that stimulate AMPK activity, and thereby inhibit SREBP, leading to reduced fatty acid production in the liver," Martins-Green added.
A research article describing the study has been published in the Journal of Hepatology.