When the flu hits, an unmistakable feeling of drowsiness sinks in. Washington State University Spokane scientists have now found a specific protein that is uniquely involved in sleep responses triggered by the influenza virus in mice. They found that the protein boosts the healing power of sleep and helps recovery. The researchers speculate that it might be possible to develop treatments based on it that might speed up recovery even more.
A sleepy protein that helps the flu go away
Professor James M. Krueger and colleagues identified the protein in question as being AcPb. The protein links up with an immune system signaling chemical called interleukin-1 to help regulate sleep in healthy animals, but also to prompt infected animals to spend more time sleeping during an illness.
The team engineered mice who lacked the gene for AcPb gave an intranasal dose of mouse-adapted H1N1 influenza virus, a strain of influenza that swept across the world in the 2009 pandemic. Normal mice who had AcPb were also infected. Infected, regular mice showed the typical prolonged sleep response, but mice lacking AcPb slept less than control mice. The latter group became chilled, grew sluggish, lost their normal circadian rhythms and ultimately died in higher numbers than the mice who slept longer.
“Influenza is a lung disease,” said Krueger, “and deaths probably occur from fluid building up in the lungs. But now, we see that without AcPb in the brain, the virus is even more deadly. Why would the brain be regulating a lung disease?”
“We knew that the virus replicated in the lungs,” he said, “but we’ve discovered it also reaches parts of the brain – causing an inflammatory reaction involving interleukin-1 and AcPb. That reaction induces the increased sleep response that helps the body overcome an infection.”
Previously, studies had shown that sleep is necessary for a healthy immune system and plays a critical role in the body’s response to bacterial and viral infections.
“This finding expands our knowledge of the molecular pathway involved in recovery from influenza,” said Krueger, who hopes virologists will take note.
The researchers speculate that it may be possible to develop a treatment, and why not a cure, to influenza based on this new-found knowledge. Krueger explains that the interleukin-1 – AcPb signaling complex is linked to a different molecule in the immune system called growth hormone releasing hormone (GHRH) and its receptor (GHRHR.) GHRHR was “previously shown to be critical to the healing sleep responses induced by the influenza virus, so this may offer another potential clinical approach to treat influenza and other microbial diseases.”
Findings appeared in Brain, Behavior and Immunity.