The finding could explain why sufferers of Alzheimer's and other neurodegenerative diseases significantly worsen following such insults. According to the scientists, such minimal "excitotoxic insults" could include brief seizures, mild head trauma or stroke, or even transient anoxia from fainting while standing too quickly.

The scientists believe that drugs to selectively inhibit the immune proteins could reduce the rate of neural damage in a wide range of neurodegenerative diseases. Such drugs could also protect other organs against damage from autoimmune diseases such as lupus and rheumatoid arthritis, in which the immune system attacks body tissues, said the scientists.

In an article in the October 24, 2002, Neuron, Zhi-Qi Xiong and James McNamara report studies of brain cell cultures that reveal how the set of immune proteins, called "complement," can kill neurons. The research was supported by the National Institutes of Health. Complement proteins circulate in the blood in an inactive form, but when triggered by infection or other invaders, they form complexes that can attack the invaders.

"For a decade or more, there have been studies in which complement proteins were detected in the vicinity of senile plaques of patients with Alzheimer's disease and also in the brain of other neurodegenerative diseases," said McNamara, who is professor and chair of the medical center's department of neurobiology. According to McNamara, while this association suggested that complement could harm neurons, evidence also existed that complement could promote removal of a damaging protein that causes the plaques in Alzheimer's disease.

The reality, Xiong and McNamara discovered, seems more complicated. The complement immune system pathway cons
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Contact: Dennis Meredith
dennis.meredith@duke.edu
919-681-8054
Duke University
23-Oct-2002