In a mouse study, the research team - including senior investigator Sean Davies, PhD, assistant professor of pharmacology at Vanderbilt - tested a bacteria that can produce a "therapeutic compound" in the gut, finding that it stopped weight gain, insulin resistance and other health complications as a result of a high-fat diet.
The researchers genetically modified E. coli Nissle 1917 bacteria to produce a compound in the gut that reduces food intake and obesity.
The findings were recently published in the Journal of Clinical Investigation.
Past research has shown that natural gut bacteria plays a role in the development of obesity, diabetes and cardiovascular disease. A 2012 study reported by Medical News Today, for example, suggested that bacteria residing in the large intestine may slow down the activity of energy-burning brown fat, contributing to the development of obesity.
"The types of bacteria you have in your gut influence your risk for chronic diseases," says Davies. "We wondered if we could manipulate the gut microbiota in a way that would promote health."
To kick-start their research, the team selected a safe strain of bacteria that colonizes the human gut - Escherichia coli Nissle 1917. The researchers explain that this particular bacteria - discovered almost 100 years ago - is used as a probiotic treatment for diarrhea.
The researchers then genetically modified this strain so it would produce a compound called N-acyl-phosphatidylethanolamine (NAPE) - a lipid usually produced in the small intestine when we eat. NAPE is then quickly converted to N-acylethanolamide (NAE) - a compound that can reduce food intake and obesity.
The researchers wanted to see whether the NAPE-producing bacteria could lower food intake and weight gain in mice who were fed a high-fat diet for 8 weeks. Some of the mice had the modified bacteria added to their drinking water during the study period, while others received a control bacteria.
Modified bacteria 'active in gut for 6 weeks'
The team found that the mice that received the NAPE-producing bacteria had significantly reduced food intake, body fat, adiposity (body fat) and hepatosteatosis (fatty liver), compared with the mice that received the control bacteria.
Furthermore, the researchers found these results remained for more than 4 weeks after the modified bacteria had been removed from the drinking water. Even 12 weeks after, the mice had significantly lower body weight and body fat than the mice that received the control bacteria during the 8-week period. The researchers note that active bacteria was present in the guts of the mice for about 6 weeks after it was removed from the water.
Although these findings are promising, Davies says the team's ultimate goal is to only have to administer one dosage of the NAPE-producing bacteria to produce a sustained effect. He adds:"Six weeks is pretty long to have active bacteria, and the animals are still less obese 12 weeks out. This paper provides a proof of concept. Clearly, we can get enough bacteria to persist in the gut and have a sustained effect. We would like for that effect to last longer."
Davies told Medical News Today that these findings do not suggest a cure for obesity because the condition can reoccur if the bacteria are lost. But he says what they have uncovered is a potential treatment for obesity:
"Since it worked in mice eating a high-fat diet, it does suggest that it will be beneficial, even if people don't change their diet to something including more vegetables and less junk food. But we expect that it would likely provide the most benefit to those who do change their diet and try to get sufficient exercise.
There are lots of people who are doing their best to change their lifestyle and it still isn't enough for them to get to and keep a healthy weight, we think this strategy will really help them."
Davies admits that it is difficult to conclude whether the modified bacteria will have the same effect in humans. "But essentially," he adds, "we've prevented most of the negative consequences of obesity in mice, even though they're eating a high-fat diet."
Davies told us that before the NAPE-producing bacteria can be tested in humans, there are a number of regulatory issues that need to be tackled.
"We do hope to test this in humans, but we will need to have FDA (Food and Drug Administration) approval to do human clinical trials and we know that we will need to engineer in some additional safety measures before approval for such trials is likely," he said.
"As exciting as our results are, we need to absolutely make sure we can control these bacteria and make sure they don't have any potential to cause harm."
Contrary to concerns surrounding increasing obesity rates, Medical News Today recently reported on a study suggesting that being overweight could actually benefit our health.
Written by Honor Whiteman