Immune Signature Predicts Poor Outcome in Flu Patients
Discovery sets stage for more effective therapies (February 10)
Scientists at St. Jude Children’s Research Hospital in Memphis, Tennessee, have identified a signature immune response that might help doctors identify which newly diagnosed influenza patients are most likely to develop severe symptoms and experience poor outcomes. The findings also help explain why infants and toddlers are at increased risk for flu complications.
The new research will appear in the upcoming issue of the American Journal of Respiratory and Critical Care Medicine.
The discovery came after the investigators tracked flu infections for 28 days in 84 individuals with community-acquired influenza. The study is still underway. The new report focuses on the 2009–2010 and 2010–2011 flu seasons.
The researchers found that patients with elevated levels of three immune-system regulators (cytokines) early in the infection were more likely to develop severe flu symptoms and to be hospitalized than were patients with lower levels of the same regulators. Study participants ranged in age from 3 weeks to 71 years old and included 41 infants and toddlers aged 23 months or younger.
The cytokine levels early in the infection were predictive of flu-related complications regardless of the patient’s age, the flu strain, the ability of the virus to replicate, and other factors.
When researchers dissected the patients’ inflammatory response, they found that elevated nasal levels of monocyte chemotactic protein 3 (MCP-3) and interferon alpha 2 (IFNa2) and elevated blood levels of interleukin 10 (IL-10) at diagnosis predicted more severe symptoms later. Moreover, increased blood levels of IL-10 and MCP-3, as well as interleukin-6, at diagnosis predicted hospitalization later.
“The problem for patients with this immune signature is likely the inflammatory environment in their airways created by the innate immune system in response to the virus,” said corresponding author Paul Thomas, PhD. “Clinically, we need to explore targeted therapies to address this problem separately from efforts to clear the virus.”
Source: St. Jude Children’s Research Hospital; February 10, 2014.