New Hope for Treating Brain Diseases

By Jane Farrell

Researchers have found that an antiviral compound may protect the brain from invading pathogens.

Scientists at Washington University School of Medicine, in St. Louis, demonstrated that the compound, interferon-lambda, tightens the blood-barrier, making it harder for the virus to invade.

The blood-brain barrier is a natural defense system that is supposed to keep pathogens out of the brain. Sometimes, however, bacteria or viruses circulating in the blood slip past the blood-brain barrier, turning routine illnesses into serious infections.

According to a news release from the university, interferon-lambda is produced naturally in the body in response to infection, but the new research suggests that larger amounts of the antiviral compound may tighten the blood-brain barrier against pathogens or possibly even faulty immune cells that can attack the brain and cause conditions such as multiple sclerosis.

The researchers said that by blocking interferon-lambda’s receptors in the brain, it may be possible one day to treat specific brain diseases such as tumors. That isn’t optimal now because the drugs in use can’t cross the blood-brain barrier.

The findings were published in Science Translational Medicine.

“We have identified a new antiviral function of interferon-lambda that doesn’t involve directly attacking a virus but stems viral invasion into the brain,” said co-senior author Robyn Klein, MD, PhD, professor of medicine. “This suggests the possibility of multiple new applications. We’re testing one of these right now, conducting studies in mice to see if interferon-lambda can help prevent brain inflammation in a mouse model of multiple sclerosis.”

In their investigation, scientists looked closely at West Nile virus infections in mice to learn more about how viruses cross the blood-brain barrier. The scientists studied mice that lacked the interferon-lambda receptor. Compared with normal mice, the mice without the receptor had higher levels of West Nile virus in the brain. The researchers found the blood-brain barrier was much more permeable to the virus in these mice, suggesting that loss of the receptor through which interferon-lambda acts had loosened the barrier.

The scientists then gave normal mice West Nile virus along with interferon-lambda. The mice received the antiviral compound at the start of the infection and two and four days later. Typically less than 20 percent of normal mice survive such a high dose of the virus, but survival rates rose to more than 40 percent after treatment with interferon-lambda.