A new study by scientists at the University of Maryland School of Medicine suggests that a drug approved for treating rheumatoid arthritis (RA) reduces severe illness and death in mice exposed to the Influenza A virus. The researchers theorize that tempering the body’s immune system response to influenza infection may lessen some of the more severe symptoms and may even reduce mortality from this virus.
The researchers found that mice infected with the Influenza A virus responded positively to a drug called Abatacept, most commonly used as a treatment for people with RA.
“We found that treating the mice with Abatacept minimized tissue damage caused by the immune response, but still enabled the body to rid itself of the virus. The mice didn’t become as sick, recovered much faster and had much less damage to the lungs, compared to mice that weren’t given the drug,” said the study’s senior author, Donna L. Farber, Ph.D., professor of surgery and microbiology and immunology at the University of Maryland School of Medicine.
“Moreover, treatment with Abatacept significantly improved survival for mice infected with a lethal dose of influenza virus,” Dr. Farber says. “The survival rate for the treated mice was 80 percent, compared to 50 percent for the mice that weren’t treated.”
The drug does not interfere with the immune system’s early, rapid response in the lungs, which helps to kill the virus, but it prevents “memory” T-cells from overreacting, which produces multiple negative effects. “It’s this overactive immune response that can make you feel sick – and can also lead to pneumonia,” she says. It is thought that this tissue damage in the lungs as a result of the aggressive immune response was the leading cause of death from pandemic strains of flu, such as the avian flu and the 1918 Spanish flu. It is also thought to be true of the early cases of H1N1 “swine” flu.
Dr. Farber says, “We believe that our findings are very significant because they provide a potential new treatment for infection by the influenza virus – one that would dampen the immune response, yet still preserve its protective effects.”
The researchers are now testing Abatacept in mice that have not previously been exposed to the flu virus, trying to determine how well they respond to the drug once they have become very sick. Instead of having “memory” T-cells, these mice have what are known as “naïve” T-cells, which have never been activated by being exposed to influenza previously. Depending on the results, Dr. Farber hopes to one day bring this promising new immunotherapy to the clinic for the benefit of patients.
Abatacept is manufactured by Bristol-Myers Squibb and marketed under the name Orencia and is approved by the U.S. Food and Drug Administration for treatment of rheumatoid arthritis. Abatacept is not approved for treating influenza.
There are three types of seasonal influenza, A, B and C, and a number of subtypes of Influenza A, including a new strain of the H1N1 virus, also known as the “swine flu,” which has recently emerged and caused illness and a number of deaths this year in Mexico, the United States and other countries around the world. The researchers report was published in the June 1 edition of The Journal of Immunology, which is now available online.