Anti-Obesity Vaccine Curbs Appetite

BOSTONResearchers at the University of Porto in Portugal have developed an anti-obesity vaccine containing the appetite-stimulating hormone ghrelin that curbs appetite and boosts calorie burning in mice. The findings, presented June 5 at the Endocrine Societys 93rd Annual Meeting, suggest an anti-ghrelin vaccine may become an alternate treatment for obesity, to be used in combination with diet and exercise.

Ghrelin is a gut hormone that promotes weight gain by increasing appetite and food intake while decreasing calorie burning. Recent research shows that bariatric surgeries, such as gastric bypass, suppress ghrelin.

The researchers developed a therapeutic vaccine using a noninfectious virus carrying ghrelin, which was designed to provoke the development of antibodies against ghrelin that would suppress the hormone. They vaccinated normal-weight mice and mice with diet-induced obesity three times and compared them with control mice that received only saline injections. Compared with unvaccinated controls, vaccinated miceboth normal-weight and obese micedeveloped increasing amounts of specific anti-ghrelin antibodies, increased their energy expenditure and decreased their food intake. Within 24 hours after the first vaccination injection, obese mice ate 82 percent of the amount that control mice ate; after the final vaccination shot they ate only 50 percent of what unvaccinated mice ate.

The effects of each vaccination lasted for the two months of the study, which for the normal 18-month lifespan of mice, corresponds to four human years. The researchers saw no toxic effects in the mice as a result of the vaccine.