[This is from January - I missed it - sorry]
by Tina Adler
(1/22/01 HeartInfo) - The most common cholesterol lowering medications, statins, suppress some functions of the immune system, and may help treat immune-related disorders, a new study suggests.
Using laboratory cultures, researchers showed for the first time that even small amounts of statins inhibit the expression of molecules called class II major histocompatability complexes (MHC-II) in a variety of immune cells, including cells lining blood vessels, Brenda Kwak, PhD, of Walter Reed Army Institute of Research, in Silver Spring, Md., and colleagues report in the December 2000 Nature Medicine.
MHC-II molecules are necessary for the activation of T cells, white blood cells that recognize foreign antigens in the body and regulate other immune cells. The statins block interferon gamma, a protein that normally makes certain immune cells express MHC-II molecules on their surface. Statins differed considerably in how much they inhibited MHC-II, the authors report.
Researchers have suspected that statins are involved in the body's immune response, but they did not understood how they worked.
"These results provide convincing evidence that statins can modulate T-cell activation," Wulf Palinski, MD, of the University of California, San Diego, writes in an editorial accompanying the article.
"This unexpected effect provides the scientific rationale for using statins as immunosuppressors," during organ transplants and perhaps in the treatment of such immune disorders as diabetes, multiple sclerosis, and rheumatoid arthritis, Kwak and colleagues assert. The diseases all involve T-cell activity similar to that inhibited by statins, said Palinski.
More research is needed on statins' effects on the immune system, before they can be used as immunomodulators, writes Palinski. Statins are common, and the drugs do not appear to increase a person's susceptibility to infection. But the possibility that statins may decrease the body's "ability to mount an immune response against foreign antigens cannot be completely ruled out," he said.
Studies already show that organ transplant patients who take statins live longer than similar patients taking a placebo. Researchers had thought the patients were benefiting from the statins' cholesterol-lowering abilities, but they may also be benefiting from the drugs' effects on T cells , researchers now say. Transplants cause chronic T-cell activation, which leads to an overgrowth of the smooth muscle cells that clogged arteries. Such clogging reduces blood flow to the new organ.
Statins may help prevent the body from rejecting the new organ, but this question needs much more investigation, researchers say.
Statins lower cholesterol concentrations in the blood and prevent heart attacks by inhibiting a liver enzyme, 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, which cells require to produce cholesterol.
Statins include the trade names atorvastatin, pravastatin, simvastatin and fluvastatin. They are used to treat high LDL cholesterol levels.
Although in vitro studies show statins inhibit T cell activation, it is unknown whether they will do so in humans. There are many medications that offer promise to patients suffering from an over active immune system. Some of these medications also provide benefits for patients who have had a transplant and need to suppress their immune system.