When the influenza pandemic of 2009 was over, scientists were fascinated—and surprised—to find that patients with asthma who were hospitalized with the flu were half as likely to die or to require intensive care compared with people without asthma.
"That finding really got me excited to understand what was happening to asthmatic patients during the pandemic," said Yoichi Furuya, PhD, Assistant Professor at Albany Medical College in Albany, New York. Dr. Furuya, who has asthma, is using a research grant from the American Lung Association to study how asthma may influence the immune system's response to influenza infection.
Using a mouse model of asthma, he found that shortly after having an asthma attack, mice infected with influenza started recovering from the flu. "We need to figure out which immune pathways are involved in this recovery process," Dr. Furuya says. "If we can do that, it would help us to design drugs against damage caused by flu infection not only in the asthmatic population but also in the general population."
Dr. Furuya has found that influenza strains other than the one that caused the 2009 pandemic can also stimulate the immune system of asthmatic people to protect against flu damage in the lungs. In an especially surprising turn of events, Dr. Furuya has found that asthma-induced inflammation may protect against damage caused by other viruses and bacteria, including antibiotic-resistant Staphylococcus aureus (MRSA) infection as well as streptococcus pneumonia. "What I observed was so striking and unexpected, that it was worthwhile to test other bacteria and viruses," he says. "The findings might one day lead to treatment against various different pathogens in people with asthma or even without asthma."
Inflammation is the body's normal response to infections. However, the immune system can overreact when it is responding to influenza, causing the lungs to become inflamed. This can clog the airways and cause difficulty breathing.
Inflammation is also an important part of asthma. When a person has an asthma attack, the lungs become inflamed. "In response to that inflammation, we start producing an anti-inflammatory protein called TGF beta," Dr. Furuya explains. "People with asthma have severe inflammation in the airways that is never resolved, so the immune system is always trying to suppress inflammation. We believe that suppression caused by asthma is actually decreasing the lung injury caused by flu infection."
He found that in asthmatic mice infected with the influenza virus, the amount of virus is similar to what is found in non-asthmatic mice, but the damage caused by the virus is much less. "The asthma is trying to suppress the inflammation as well as damage from the infection, so it's actually protecting the mice," he says."The same process may be occurring in humans. A treatment involving TGF-beta might help prevent influenza-related mortality."
Page last updated: March 2, 2020