ScienceDaily News Release: Brain’s Immune System Triggered In Autism

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Source: s Hopkins Medical Institutions

Date Posted: 2004-11-17

Web Address: http://www.sciencedaily.com/releases/2004/11/041117004123.htm

BRAIN’S IMMUNE SYSTEM TRIGGERED IN AUTISM

A s Hopkins study has found new evidence that the brains of some people with

autism show clear signs of inflammation, suggesting that the disease may be

associated with activation of the brain’s immune system.

“These findings reinforce the theory that immune response in the brain is

involved in autism, although it is not yet clear whether the inflammation is a

consequence of disease or a cause of it, or both,” said Pardo-Villamizar,

M.D., assistant professor of neurology and pathology at s Hopkins and senior

author of a report on the study published early on-line in the journal ls of

Neurology on Nov. 15.

Whatever the cause of the inflammation, it may provide a good target for

developing new treatments, adds Pardo.

Autism is a disorder of the developing brain that appears in early childhood.

According to the American Neurological Association, it is estimated to afflict

between two and five of every 1,000 children and is four times more likely to

strike boys than girls. Children with autism have difficulties in social

interaction and communication and may show repetitive behaviors and have unusual

attachments to objects or routines.

Autism has a strong genetic component in some families, although other causes

likely play a role, possibly including birth complications, diet, toxins or

infections, says Pardo.

“Scientists have found hints that the immune system may be involved in autism,

but not all studies have confirmed this,” said Pardo. “We wanted a more

definitive answer, so rather than looking at the overall immune system, we

focused on immune responses inside the relatively sealed environment of the

nervous system.”

Led by first author L. Vargas, M.D., a postdoctoral fellow working in

Pardo’s laboratory, the researchers examined tissue from three different regions

of the brain in 11 people with autism, ages 5 to 44 years, who had died of

accidents or injuries. They also measured levels of two immune system proteins,

called cytokines and chemokines, found in the cerebrospinal fluid - the clear

substance that surrounds, bathes and nourishes the brain and spinal cord - in

six living patients with autism, ages 5 to 12 years.

Compared with normal control brains, the brains of people with autism showed

evidence of an ongoing inflammatory process in different regions of the brain

and produced by cells known as microglia and astroglia, says Pardo. Cytokine

and chemokine levels in the cerebrospinal fluid also were abnormally elevated in

patients with autism.

“These findings suggest that the inflammation is localized to specific regions

within the brain and not caused by immune system abnormalities from outside the

brain,” says Pardo.

Pardo and colleagues are now studying how the genetic background of patients and

families may influence immune system reactions in the brain associated with

autism.

Other authors are Zimmerman, Caterina Nascimbene, and Chitra Krishnan.

The study was funded by the Cure Autism Now Foundation, the Autism Research

Foundation, the National Institutes of Health, Dr. Barry and Gordon and an

anonymous donor.

On the Web:

http://www3.interscience.wiley.com/cgi-bin/jhome/76507645

http://www.neuro.jhmi.edu/

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