Featured Research

from universities, journals, and other organizations

High-fat Diet Makes Mice Susceptible To Liver Injury

Date:
November 3, 2007
Source:
John Wiley & Sons, Inc.
Summary:
A high-fat diet may kill regulatory T cells in the liver, allowing steatosis to develop into steatohepatitis, according to a new article. Related depletion of regulatory T cells in fatty liver may explain why.

A high fat diet may kill regulatory T cells in the liver, allowing steatosis (simple fatty liver) to develop into steatohepatitis (fatty liver with inflammation), according to the results of a new study.

Nonalcoholic fatty liver disease (NAFLD), a condition related to obesity, can range in severity from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH) to cirrhosis which can lead to death. However, the progression of the disease is not well understood. The prevailing hypothesis suggests two-hits are necessary. The first is prolonged over-nutrition which causes the accumulation of fat in the liver. The second hit has been hypothesized to involve oxidative stress, mitochondrial injury or inflammatory cytokine production involving regulatory T cells (Tregs).

Tregs have recently emerged as a key player in hepatic immune regulation, so researchers, led by Xiong Ma of Johns Hopkins University in Baltimore, sought to determine their role in the pathogenesis of NASH. They hypothesized that regulation by Tregs is decreased in a fatty liver, which makes inflammation worse when the organ is exposed to secondary injury.

To test this hypothesis, they fed adult mice a high-fat diet to induce obesity, steatosis, and insulin resistance similar to that seen in humans. (Mice in the control group were fed a normal diet.) They examined the mice's hepatic lymphocyte population by flow cytometry. The researchers then injected the mice with liver inflammation-causing exogenous lipopolysaccarhide (LPS, a bacterial toxin usually presented in the normal intestine and carried to the liver by blood flow), and examined serum and liver tissue of the sacrificed mice.

They found that the hepatic Tregs gradually decreased during the administration of the high-fat diet and, at the end of 8 weeks, the levels were less than half of those in mice who ate a normal diet. The high-fat diet induced simple steatosis, and made the mice more susceptible to the LPS. Those on the high fat diet, who had depleted Tregs, sustained greater liver injury after they were exposed to the LPS.

"To our knowledge, this is the first time that Tregs have been linked to the inflammatory process in diet-induced steatosis," the authors report. Interestingly, they also found that the Treg depletion reversed itself when the mice were switched from a high-fat to a normal-fat diet.

"In conclusion, our study demonstrates that Tregs may play a critical role in controlling hepatic inflammation," the authors write. "We speculate that the depletion of Tregs may be the key event in the transition from simple steatosis to steatohepatitis." Their results also suggest that strategies aimed at increasing the number and/or function of Tregs should be explored to improve the prognosis of NAFLD.

Article: "A High-Fat Diet and Regulatory T Cells Influence Susceptibility to Endotoxin-Induced Liver Injury." Ma, Xiong; Hua, Jing; Mohamood, Abdiaziz; Hamad, Abdel; Ravi, Rajani; Li, Zhiping. Hepatology; November 2007; (DOI: 10.1002/hep.21823).


Story Source:

The above story is based on materials provided by John Wiley & Sons, Inc.. Note: Materials may be edited for content and length.


Cite This Page:

John Wiley & Sons, Inc.. "High-fat Diet Makes Mice Susceptible To Liver Injury." ScienceDaily. ScienceDaily, 3 November 2007. <www.sciencedaily.com/releases/2007/11/071101144851.htm>.
John Wiley & Sons, Inc.. (2007, November 3). High-fat Diet Makes Mice Susceptible To Liver Injury. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2007/11/071101144851.htm
John Wiley & Sons, Inc.. "High-fat Diet Makes Mice Susceptible To Liver Injury." ScienceDaily. www.sciencedaily.com/releases/2007/11/071101144851.htm (accessed October 20, 2014).

Share This



More Health & Medicine News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How Nigeria Beat Its Ebola Outbreak

How Nigeria Beat Its Ebola Outbreak

Newsy (Oct. 20, 2014) The World Health Organization has declared Nigeria free of Ebola. Health experts credit a bit of luck and the government's initial response. Video provided by Newsy
Powered by NewsLook.com
Another Study Suggests Viagra Is Good For The Heart

Another Study Suggests Viagra Is Good For The Heart

Newsy (Oct. 20, 2014) An ingredient in erectile-dysfunction medications such as Viagra could improve heart function. Perhaps not surprising, given Viagra's history. Video provided by Newsy
Powered by NewsLook.com
Ebola Worries End for Dozens on U.S. Watch Lists

Ebola Worries End for Dozens on U.S. Watch Lists

Reuters - US Online Video (Oct. 20, 2014) Forty-three people who had contact with Thomas Eric Duncan, the first person diagnosed with Ebola in the U.S., were cleared overnight of twice-daily monitoring after 21 days of showing no symptoms. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Beijing Marathon Runners Brave Hazardous Air Pollution

Beijing Marathon Runners Brave Hazardous Air Pollution

AFP (Oct. 19, 2014) Tens of thousands of runners battled thick smog at the Beijing Marathon on Sunday, with some donning masks as the levels of PM2.5 small pollutant particles soared to 16 times the maximum recommended level. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins