Cholesterol-metabolizing gut bacteria?

Hypercholesterolemia, i.e. elevated circulating cholesterol levels, is strongly associated to the development and progression of cardiovascular diseases, that are responsible for one out of every four deaths in developed countries¹. Drugs such as statins are therapeutic strategies that lower blood cholesterol levels. Unfortunately, these molecules do not act on dietary cholesterol and can have many side effects. What if a new avenue for the treatment of hypercholesterolemia was found deep in our gut

Uncovering the mechanism at play in humans

Researchers recently identified within the gut microbiota the mechanism responsible for cholesterol metabolism by some bacteria, thus decreasing fecal and blood levels. The idea that some gut bacteria can break down cholesterol is not new since this bacterial activity was already well known for a hundred years. But the exact functioning could never be identified in humans because most of bacteria are hard to cultivate in petri dishes in laboratory settings, thus making their study extremely complicated.

A key player: IsmA gene

Using multiple analytical methods, the researchers identified within these bacteria the IsmA gene (Intestinal Steroid Metabolism A) which could be involved in intestinal cholesterol metabolism. People carrying this gene in their gut microbiota had reduced (55% to 75%) cholesterol contents in their stool compared to non-carriers. Blood cholesterol levels were also lower in carriers.

Towards new therapeutic strategies?

This new promising research could lead to new strategies targeting the gut microbiota: by introducing these cholesterol-metabolizing bacteria in the gut microbiota or by increasing their number using prebiotics, it could be possible to fight high blood cholesterol levels.

^{1 Goldstein, J.L., and Brown, M.S. (2015). A century of cholesterol and coronaries: from plaques to genes to statins. Cell 161, 161–172.}