Obesity and chronic liver disease might be infectious, triggered by a family of proteins that alter populations of microbes in the stomach, according to a report by Yale University scientists in the February 1 advance online publication of Nature.
The Yale scientists said that the altered intestinal environment that led to obesity and liver disease was infectious among the community of mice. Richard A. Flavell is Professor of immunobiology at Yale School of Medicine and senior author of the study. He said:
When healthy mice were co-housed with mice that had altered gut microbes, the healthy mice also developed a susceptibility for development of liver disease and obesity.
The proteins in question are called inflammasomes. They are responsible for launching the immune system’s inflammatory response. Inflammasomes act as sensors and regulators of the microbial environment of the intestines.
The Yale team found that a deficiency in components of two particular inflammasomes in mice resulted in the development of an altered microbial community associated with increased bacteria. This determined the severity of non-alcoholic fatty liver disease (NAFLD) and obesity in the mice.
NAFLD is the result of metabolic syndrome, a collection of disorders that includes obesity and diabetes, and is the leading cause of chronic liver disease in the western world. It is estimated that up to 30 million people suffer from NAFLD in the United States alone. Twenty percent of people with NAFLD develop chronic liver inflammation, placing them at risk for cirrhosis and liver cancer, but the causes have been unclear.
The next step, Flavell said, is extending this research to humans and to identify more precisely the bacteria involved in the progression to liver disease. He said:
We found, in mice, that targeted antibiotic treatment brought the microbial composition back to normal, and thus eased the liver disease. Our hope is that our findings may eventually lead to a treatment for humans.
Bottom line: A report by Yale University scientists in the February 1 advance online publication of Nature suggests that obesity and chronic liver disease might be infectious, triggered by a family of proteins that alter populations of microbes in the stomach.