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Researchers make new discoveries on what does and doesn't affect immune system
http://www. physorg. com/ news121366855. html
February 04, 2008
Scientists now know some factors that can affect the body's immune system: poor diet, certain steroids, chronic stress. Now, researchers at Michigan State University (MSU) have discovered that a hormone that controls appetite can also affect the immune system, while a natural version of a certain steroid does not.
Both studies are reported in this week's online edition of PNAS.
"These two studies, although not directly related, demonstrate the important role the neuroendocrine system plays in both the immune system and obesity," said Pamela Fraker, a professor of biochemistry and molecular biology at MSU and the lead scientist on both projects. "MSU is one of the few places studying metabolism, the immune system, and the neuroendocrine system."
A New Role for Leptin
An MSU research team discovered that leptin, a hormone produced by fat cells, supports the production of white blood cells in the body, enhancing immune function. This is the first time the effect of leptin on the immune system has been demonstrated.
Scientists have long known that leptin helps control how much a person eats and how quickly the body burns energy.
"Many studies have been trying to unlock the key to obesity for years," Fraker said. "The fatter a person is, the more leptin there is in the bloodstream. In obese individuals, the body seems to become 'resistant to leptin'—this signal gets blocked. So giving leptin to obese people does not help them lose weight."
MSU scientists examined ob/ob mice (genetically modified to have non-functional leptin) and db/db mice (genetically modified to have non-functional leptin receptors), giving them leptin supplements to study the effects. While causing the mice to eat less, the biggest surprise was the effect of leptin on the immune system. Mice given leptin doubled their number of B cells, a type of white blood cell produced in the bone marrow that fights infections by producing antibodies.
"This is a brand new role for leptin," Fraker said. "It seems that most obese individuals may be somewhat immunosuppressed. This finding demonstrates that the body's resistance to leptin also plays a role in this."
To further study the effects of leptin on the immune system, Fraker and her colleagues plan to conduct a study on morbidly obese individuals who will undergo gastric bypass surgery. Although the outcomes of this surgery are highly successful for most people, the mortality rate is significant, at 2-10%.
"Infections from poor wound healing, due to reduced immune function, are one of the reasons people die from this surgery," Fraker said. "We will measure people's immune function before and after surgery to see how much it improves and how quickly it improves."Other members of this research team include MSU scientist Louis King, assistant professor of biochemistry and molecular biology, and Kate Claycombe, assistant professor of food science and human nutrition.
Naturally occurring steroids do not suppress the immune system
When corticosteroids, such as prednisone, reduce inflammation, they also suppress the body's immune system—people taking prescription steroids are more susceptible to infections. Another MSU team discovered that naturally occurring corticosteroids in the body do not have the same immunosuppressive effects.
The human body secretes corticosteroids under stress (whether psychological or physiological), and these steroids are responsible for the "fight-or-flight response" in humans and other animals. Cortisol (also known as hydrocortisone) is the most abundant corticosteroid in the body. The anti-inflammatory effects of these steroids are well-known, and pharmaceutical companies have been manufacturing them for about 20 years. However, users are warned that wounds and bruises heal more slowly due to the effects of steroids on the immune system.
Fraker and his team were the first to discover that the naturally produced version of steroids does not affect the immune system in the same way as the pharmaceutical version.
"Using the pharmacological version of steroids, you lose some immune functions," Fraker explained. "With the natural version, you retain the function of neutrophils. For pharmaceutical companies, it might be worth investigating the synthetic and natural versions of steroids."
Source: http:/ / only- perception. blogs……/ 2008/ 03/ blog- post_4354. html
New Discoveries on Leptin and Steroids in the Immune System
http://www. physorg. com/ news121366855. html
February 04, 2008
Scientists now know some factors that can affect the body's immune system: poor diet, certain steroids, chronic stress. Now, researchers at Michigan State University (MSU) have discovered that a hormone that controls appetite can also affect the immune system, while a natural version of a certain steroid does not.
Both studies are reported in this week's online edition of PNAS.
"These two studies, although not directly related, demonstrate the important role the neuroendocrine system plays in both the immune system and obesity," said Pamela Fraker, a professor of biochemistry and molecular biology at MSU and the lead scientist on both projects. "MSU is one of the few places studying metabolism, the immune system, and the neuroendocrine system."
A New Role for Leptin
An MSU research team discovered that leptin, a hormone produced by fat cells, supports the production of white blood cells in the body, enhancing immune function. This is the first time the effect of leptin on the immune system has been demonstrated.
Scientists have long known that leptin helps control how much a person eats and how quickly the body burns energy.
"Many studies have been trying to unlock the key to obesity for years," Fraker said. "The fatter a person is, the more leptin there is in the bloodstream. In obese individuals, the body seems to become 'resistant to leptin'—this signal gets blocked. So giving leptin to obese people does not help them lose weight."
MSU scientists examined ob/ob mice (genetically modified to have non-functional leptin) and db/db mice (genetically modified to have non-functional leptin receptors), giving them leptin supplements to study the effects. While causing the mice to eat less, the biggest surprise was the effect of leptin on the immune system. Mice given leptin doubled their number of B cells, a type of white blood cell produced in the bone marrow that fights infections by producing antibodies.
"This is a brand new role for leptin," Fraker said. "It seems that most obese individuals may be somewhat immunosuppressed. This finding demonstrates that the body's resistance to leptin also plays a role in this."
To further study the effects of leptin on the immune system, Fraker and her colleagues plan to conduct a study on morbidly obese individuals who will undergo gastric bypass surgery. Although the outcomes of this surgery are highly successful for most people, the mortality rate is significant, at 2-10%.
"Infections from poor wound healing, due to reduced immune function, are one of the reasons people die from this surgery," Fraker said. "We will measure people's immune function before and after surgery to see how much it improves and how quickly it improves."Other members of this research team include MSU scientist Louis King, assistant professor of biochemistry and molecular biology, and Kate Claycombe, assistant professor of food science and human nutrition.
Naturally occurring steroids do not suppress the immune system
When corticosteroids, such as prednisone, reduce inflammation, they also suppress the body's immune system—people taking prescription steroids are more susceptible to infections. Another MSU team discovered that naturally occurring corticosteroids in the body do not have the same immunosuppressive effects.
The human body secretes corticosteroids under stress (whether psychological or physiological), and these steroids are responsible for the "fight-or-flight response" in humans and other animals. Cortisol (also known as hydrocortisone) is the most abundant corticosteroid in the body. The anti-inflammatory effects of these steroids are well-known, and pharmaceutical companies have been manufacturing them for about 20 years. However, users are warned that wounds and bruises heal more slowly due to the effects of steroids on the immune system.
Fraker and his team were the first to discover that the naturally produced version of steroids does not affect the immune system in the same way as the pharmaceutical version.
"Using the pharmacological version of steroids, you lose some immune functions," Fraker explained. "With the natural version, you retain the function of neutrophils. For pharmaceutical companies, it might be worth investigating the synthetic and natural versions of steroids."
Source: http:/ / only- perception. blogs……/ 2008/ 03/ blog- post_4354. html