2 March 2011
Bacteria in gut can control organs
by Kate Melville
The bacteria that live in the human gut may be doing quite a bit more than simply helping us digest food. Researchers have observed that bacteria in the digestive tract also appear to be exerting some level of control over the metabolic functions of organs such as the liver.
The finding, in the journal Bio, offers an intriguing insight into the symbiotic relationship between humans and their gut microbes and how changes to the microbiota impact overall health. "The gut microbiota enhances the host's metabolic capacity for processing nutrients and drugs and modulates the activities of multiple pathways in a variety of organ systems," says researcher Sandrine Claus, from Imperial College, London.
In the study, Claus and her co-researchers exposed germ-free mice to bedding that had previously been used by conventional mice with normal microbiota and followed their metabolic profiles for 20 days to observe changes as they became colonized with gut bacteria.
Over the first 5 days after exposure, the mice exhibited a rapid increase in weight (4 percent). Colonization also triggered a number of processes in the liver in which sugars (glucose) are converted to starch (glycogen) and fat (triglycerides) for short-term and long-term energy storage. Statistical modeling between liver metabolic functions and microbial populations determined that the levels of glucose, glycogen and triglycerides in the liver were strongly associated with a single family of bacteria known as Coriobacteriaceae.
"Here we describe the first evidence of an in vivo association between a family of bacteria and hepatic lipid metabolism. These results provide new insights into the fundamental mechanisms that regulate host-gut microbiota interactions."
Although she is cautious about extrapolating the findings from mice to humans, Claus says the research will provide a basis to develop new strategies to beneficially modulate host metabolism by altering microbial communities in the gut. "[The results should be of] wide interest to microbiological, nutrition, metabolic, systems biology and pharmaceutical research communities," she concluded.
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Source: American Society for Microbiology