NEW YORK -- June 18, 2008 -- Weight loss after gastric bypass surgery may heighten immune defense against infection and cancer, and laparoscopic weight-loss surgery may improve health in morbidly obese teens, according to 2 separate studies presented at the Endocrine Society's 90th Annual Meeting in San Francisco.
In the first study, investigators analysed the effect of weight loss on immune function. "Obesity is related to a higher rate of infections and some types of cancer," said coauthor, Alfredo Halpern, PhD, University of São Paulo, São Paulo, Brazil. "Nevertheless, there are only a few published studies evaluating the immune function in severely obese patients and the effect of surgery-induced weight loss on these parameters."
The study included 28 morbidly obese patients who had traditional gastric bypass surgery. The 20 women and 8 men lost an average of 78.5 lbs 6 months after gastric bypass.
Six months before and after the surgery, the researchers evaluated patients' blood samples for natural killer (NK) cells. Specifically, they measured the number of NK cells and the cells' capacity to kill infected cells or tumour cells. They also looked at the production of certain cytokines.
Although the number of NK cells did not increase with surgically induced weight loss, their activity changed, according to Dr. Halpern. Before surgery, NK cells mounted a weak immune defense, but after surgery their activity increased by nearly 79%, representing an improvement in the effective immune response and, possibly, in the ability to fight cancer and infections.
The response of cytokines involved in NK cell activity also changed after weight loss, possibly affording higher protection against infection and cancer. Cytokines analysed were interferon-gamma and interleukins 2, 12, and 18.
Prior studies have shown that bariatric surgery has many health benefits, including resolution of type 2 diabetes, improved blood pressure and lower risk of premature death. This study shows another possible benefit of the weight loss stemming from bariatric surgery.
"It may help protect against infections and cancer by improving the activity of certain immune cells," Dr. Halpern said.
The second study aimed to document the impact of laparoscopic gastric banding (Lap-Band) on the medical complications of obesity or their risk factors, in adolescents.
The study was part of the multidisciplinary US Food and Drug Administration (FDA)-approved Lap-Band Trial for Teens being performed at Columbia University, New York, New York. The FDA has approved the procedure for use in adults but not yet in teenagers.
Previous studies suggest that this minimally invasive surgery is a safe and effective way for morbidly obese teens to lose weight, said lead author, Ilene Fennoy, MD, Morgan Stanley Children's Hospital of New York-Presbyterian and Columbia University College of Physicians and Surgeons, New York, New York.
The study included 14 morbidly obese adolescents, 6 boys and 8 girls, aged 14 to 17 years. Patients received dietary counselling and encouragement to exercise, both before and after surgery. Six months after surgery, patients lost an average of 20 lbs.
The patients' blood pressure did not greatly change, but they had significant improvement in other measures of medical disorders. Several metabolic risk factors improved, including abdominal fat, high triglycerides, and average blood sugar as measured by hemoglobin A1C. The patients' liver function and a measure of immune response also improved.
"Laparoscopic gastric banding offers the possibility of a new therapy for morbidly obese adolescents who have medical complications," Dr. Fennoy said.
SOURCE: The Endocrine Society
E-Mail this DGNews to a colleague
