A new role for leptin

One MSU research team discovered that leptin. a hormone produced by fat cells. supports body enhancing immune function. van leucocytproduction in the. Het immuunsysteem van leptin van This is the first time effect on the has been demonstrated.

Scientists have long known that leptin helps control how much a person eats as well as how quickly the body burns energy.

"Many investigators have been trying to unlock the key to obesity for years," said Fraker. "The more fat a person has, the more leptin there is in the bloodstream. In obese people, it seems that the body becomes leptin-resistant -- the signals get jammed. So giving obese people leptin doesnot help them lose weight."

The MSU scientists were examining ob/ob mice (genetically programmed to have non-functional leptin) and db/db mice (genetically programmed to have non-functional leptin receptors), giving them supplemental leptin to study its effects. Het causing the mice to eat less. van While the big surprise was het immuunsysteem van leptin effect on the. The mice that were given leptin had de double the number of a type of leucocyt B cells. in bone marrow that fights infection by making antibodies. produced

"This is a brandnew role for leptin," said Fraker. "It appears that most obese people may be somewhat immunosuppressed. This finding shows us that the body's resistance to leptin plays a role in that, too."

Van het immuunsysteem. and her colleagues are planning a study on Fraker van study leptin van To further effect on the van peoplewho morbidly obese having gastric bypasssurgery will be. Sterftecijfers. van surgery is highly - de successful for van While the outcome of the most people can range from 2 to 10 percent significant. which is.

From poor „Infection het gekronkeld reduced healing. which is the result of immune function. is one reason people die from the surgery.“ Fraker said. "Weare going to measure people's immune function before and after surgery to see how much it improves, as well as how fast it improves."

Other members of this research team are MSU scientists Louis King, research assistant professor of biochemistry and molecular biology, and Kate Claycombe, assistant professor of food science and human nutrition.

Naturally-Produced steroids do not inhibit immuunsysteem

Van corticosteroids. such as van While van prednisone. reduce inflammation. van theyalso het body immuunsysteem inhibit the -- a person taking prescription steroids is more susceptible to infection. Another MSU research team found that corticosteroids produced naturally in the body donot have this same immunosuppressive effect.

The human body secretes corticosteroids when itis under stress, both psychological and physical, and these steroids are responsible for the "fight-or-flight response" in humans and other animals. Cortisol (also called hydrocortisone) is the most abundant corticosteroid in the body. These steroids' anti-inflammatory effects are well-known and pharmaceutical companies have been making versions of them for about 20 years. Het taking van But people steroids are warned that cuts and bruises het immuunsysteem van may steroids van be slow to heal because of effects on the.

Discovery van Fraker and her team that the naturally-produced het immuunsysteem van versions of the steroids do not affect the like the pharmacological versions is the first time this has observed. been

"With the pharmacological versions of steroids, you lose some immune function," Fraker explained. „With the natural de leucocyt] function van versions. you retain neutrophil [a type of. It may be worthwhile for pharmaceutical companies to investigate synthesizing natural versions of the steroids."

In addition to Fraker and King, other members of this research team are Mark Trottier, MSU research assistant professor of biochemistry and molecular biology, and Matthew Newsted, undergraduate research assistant.

Both of these researcher projects are supported by the National Institutes of Health. The work of Fraker and Claycombe is also supported by the Michigan Agricultural Experiment Station.