Autoimmunity May Be Involved in Eating Disorders

NEW YORK (Reuters Health) - An erroneous immune reaction against "self" proteins seems to play a role in psychological aspects of disordered eating, Swedish researchers report.

They found that levels of autoantibodies to a hormone dubbed alpha-MSH are related to traits such as body dissatisfaction in patients with anorexia and bulimia. Alpha-MSH is involved in both the stress response and appetite control, the team points out in the research journal PNAS Early Edition.

Dr. Serguei O. Fetissov of the Karolinska Institute in Stockholm and colleagues had previously found alpha-MSH autoantibodies in anorexia and bulimia patients and in unaffected "control" subjects. In the current study, the researchers measure the levels of autoantibodies to alpha-MSH in 12 patients with anorexia, 42 with bulimia, and 41 healthy controls.

Some healthy participants showed higher autoantibody levels than patients with eating disorders, the researchers found, making it clear that elevated levels of autoantibodies do not cause the disease.

However, Fetissov and his team explain, it is possible that an increase in the permeability of the blood-brain barrier, caused by stressful events, for example, could allow the normally harmless autoantibodies to create mental problems.

The researchers found significant correlations between levels of autoantibodies to alpha-MSH and scores on a standardized eating disorder scale. Most defining traits of the eating disorders were linked to levels of alpha-MSH autoantibodies.

"Remarkably," say the investigators, these correlations were opposite in anorexia and bulimia patients.

Further investigations in lab animals could clarify the role of these autoantibodies, the investigators conclude, with the aim of developing novel treatments for eating disorders.

SOURCE: PNAS Early Edition, online September 26, 2005.