People may dislike the idea, but genetically modified bacteria are an incredibly useful scientific tool. By inserting genes for desirable molecules, scientists can convert the organisms into mini-factories that churn out useful therapeutics like insulin and antiviral proteins. They can even be tweaked to help clean up pollution or even increase soil fertility. And now, scientists may have found yet another use for engineered microbes: tackling obesity.
Scientists from Vanderbilt University have programmed a common gut bacterium to produce molecules that have been previously shown to reduce food intake. After administering these microbes to mice on a high fat diet, they ate less, had lower body fat and were less likely to develop fatty liver disease. Furthermore, the effects lasted for several weeks, suggesting these organisms could be a useful tool for treating obesity in humans. The findings were described at the 249th National Meeting & Exposition of the American Chemical Society.
We know that obesity is associated with all sorts of health problems, such as diabetes and heart disease, but unfortunately treating it is not as simple as advising lifestyle changes. Although it is evidently a complex disease, scientists are now beginning to understand the roles played by our gut microbes, which have been shown to influence our weight, and are hoping to use this knowledge to their advantage to come up with effective treatments.
Vanderbilt scientists, for example, are modifying bacteria to produce and release therapeutic compounds with the hope of developing low cost, sustainable treatments for various chronic diseases, including obesity. For their current investigation, they chose to engineer a strain of the common gut bacterium E. coli that is prescribed as a digestive probiotic in Europe. They inserted genes for hunger-suppressing molecules called NAPEs, which are usually produced in the gut in response to feeding. In some obese people, however, they’re produced in insufficient amounts, meaning they don’t feel full after meals and thus overeat.
To test out these microbes, the scientists added them to the drinking water of mice fed a high fat diet and then compared them to control animals who were just given plain water. They found that the treated mice ate less than control mice, gained 15% less weight and did not develop diabetes. Furthermore, the effects lasted for up to 12 weeks after administration, indicating that the organisms manage to take up residence in the gut, even if only temporarily. This is obviously a desirable outcome as it would eliminate the need for daily pill-taking.
Although these early results are promising, the researchers still have a long way to go. The treatment has only been tested in mice, and many more pre-clinical trials will be required before FDA approval for human studies will be granted. Furthermore, there are also concerns over safety and efficacy. There needs to be a way to prevent these organisms from accidentally entering the wrong person, such as a child or someone with a particular disease, where they could be detrimental to health. But the researchers told MIT that they’re already working on a way to avoid this, such as adding in a “kill switch” triggered by another administered compound, or engineering them in such a way that they don’t survive outside the gut.