Our gut as we all know is home to innumerable different bacteria — a complex ecosystem that has an active role in a variety of bodily functions. In a study published on the 13th May 2013 in Proceedings of the National Academy of Sciences, a team of researchers finds that in mice, just one of key bacterial species plays a major part in controlling obesity and metabolic disorders such as type 2 diabetes.
The bacterium, unfamiliar to many of us and called Akkermansia muciniphila, digests the epithelial mucus and makes up 3–5% of the microbes in a healthy mammalian gut. But the intestines of obese humans and mice, and those with type 2 diabetes, have much lower levels. The researchers led by Patrice Cani, who studies the interaction between gut bacteria and metabolism at the Catholic University of Louvain in Belgium, decided to investigate the link.
Mice that were fed a high-fat diet, the researchers found, had 100 times less A. muciniphila in their guts than mice fed normal diets. The researchers were able to restore normal levels of the bacterium by feeding the mice live A. muciniphila, as well as ‘prebiotic’ foods that encourage the growth of gut microbes.
The effects of this treatment were dramatic. Compared with untreated animals, the mice lost weight and had a better ratio of fat to body mass, as well as reduced insulin resistance and a thicker layer of intestinal mucus. They also showed improvements in a host of other indicators related to obesity and metabolic disorders.
“We found one specific common factor between all the different parameters that we have been investigating over the past ten years,” says Cani.
Cani’s team has started unravelling the complicated mechanisms through which the bacterium may influence metabolism. Restoring normal levels of A. muciniphila led to increased intestinal levels of endocannabinoids, signalling molecules that help to control blood-glucose levels and maintain the gut’s defences against harmful microbes.
Internal Cross Talk
A. muciniphila also seems to have a ‘dialogue’ with the cells of the intestinal lining and with the immune system, says Cani, sending a signal that affects the production of anti-microbial molecules, while increasing the production of mucus. It seems as if the bacterium is telling the host that it will take care of any invading harmful microbes in exchange for more food, he adds.
Cani “strongly believes” that A. muciniphila could one day be used to treat disorders such as obesity, diabetes and colitis in humans. “There is so much evidence in the literature that links this bacterium to human conditions,” he says.
As investigations continue, it will not be long before human studies using foods and bacterial species demonstrate their role in numerous behaviourally induced non communicable disease.