It is widely known that alcohol damages liver cells. In a new study, researchers found that alcohol consumption allows bacteria to infiltrate the liver, making it prone to liver disease.
Researchers from the University of California, San Diego found that alcohol may promote the migration of gut bacteria to the liver. The liver normally encounters all the blood coming from the intestine, making it possible for gut bacteria to infiltrate the organ.
Published in the journal Cell Host & Microbe, the study shows that chronic alcohol consumption alters the antibacterial immune system in the intestines of laboratory mice. It suppresses the production of a protein called REG3B and REG3G, which are naturally occurring antimicrobials.
"Alcohol appears to impair the body's ability to keep microbes in check," says Dr. Bernd Schnabl from UC San Diego's School of Medicine. "When those barriers break down, bacteria that don't normally colonize the liver end up there, and now we've found that this bacterial migration promotes alcohol liver disease."
Schnabl adds that coming up with strategies that would restore how the body defends itself against microbes might help in treating liver disease.
The team found that the mice modified to lack the protein REG3G had increased levels of bacteria after consuming alcohol. These mice also developed more severe alcoholic liver disease than normal mice.
When REG3G was over-expressed in the intestine, the mice manifested lower levels of bacteria and a reduced liver disease. To test the relevance of their findings, the researchers measured the levels of gut bacteria in alcoholic humans. The results revealed that the quantities of bacteria in their livers were elevated.
"Since expression of REG3 is reduced by chronic alcohol consumption in mice and humans, a strategy designed to increase intestinal concentrations of REG3 lectins or their production by intestinal epithelial cells might be developed to prevent alcohol-induced liver disease," the researchers conclude. They add that further studies are still needed to determine if REG3 lectins can be used as an intervention to treat alcohol-induced liver disease.
According to the National Institute on Alcohol Abuse and Alcoholism, out of the 71,713 total liver disease deaths in 2013, 46.4 percent involved alcohol use. Of the 46,240 deaths among males, 48.9 percent involved alcohol. Alcohol was also involved in 42.7 percent of the 25,433 deaths among females.
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