Immune system's overreactions can exacerbate influenza

A century after the 1918 influenza pandemic that infected approximately one-third of the world's population and killed at least 50 million people, scientists have a better  understanding of how most of those people died.
Scientists believe that the cause was the immune system's overreactions triggered by the virus. The majority of the 18,000 people who died in the 2009 swine flu epidemic also fell prey to an immune system overreaction, the Washington Post reports.
Researchers have uncovered how the influenza virus works on the cellular level by using the body's own defenses against it. The research could lead to more effective flu drugs and radically different methods for treating all kinds of infections.
“This is where the science [on epidemiology] is right now,” Trish Perl, a senior epidemiologist at Johns Hopkins Hospital, said, according to the Washington Post. “That’s what happens with a lot of severe infections...It’s almost like the system goes into overdrive.”
When trying to destroy flu-infected cells, the immune system also destroys legions of healthy cells throughout the body. In most cases, the immune response isn't too severe, but in some cases, an infection can trigger a destructive reaction called a cytokine storm. When an overabundance of these immune system signal senders floods into a part of the body, damage can occur throughout the body.
Michael Oldstone, a virologist at the Scripps Research Institute in La Jolla, Calif., and two other researchers have identified a cell, S1P1, that responds to cytokines. They've also figured out how to turn off that cell's signals, which could lead to a new class of immune-reaction blocking drugs that could be more effective than current antivirals.
“It is likely that a single oral dose of a compound can be developed that will provide protection against cytokine storms,” Hugh Rosen, Oldstone’s colleague at the Scripps Institute who also worked on the cytokine study, said, according to the Washington Post.
These drugs could be more effective than antivirals, because they target the flu effects that cause the most damage to the body. Oldstone said the next step for his team is to attempt to replicate the mouse study using ferrets, then primates and then humans.