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Society-Funded Mouse Study Shows Possible Mechanisms Underlying Flu Severity in People with MS

February 28, 2017

SUMMARY
  • Researchers at Johns Hopkins University set out to understand why people with MS may be more susceptible to infections, especially in the lungs, than people without MS.
  • They report that mice with the MS-like disease MS experienced altered immune activity in their lungs, and when infected with flu virus, they were less able to clear the virus and much more likely to die of flu compared to mice without EAE.
  • The study, supported by the National MS Society, provides important clues for increasing our understanding of why people with MS experience more severe infections.
  • The team (including Drs. Katharine Whartenby, Justin Glenn and Peter Calabresi) published these results in The Journal of Experimental Medicine (published online January 5, 2017). 
DETAILS
Background: People with MS appear to be more susceptible to infections than people of similar ages without MS, and the lungs are particularly vulnerable. The lung is a site of inappropriate activation of the immune system in people with MS, and this may cause damage to the lung and worsen both MS and infections. When people with MS contract the flu or other respiratory infection, they tend to get sicker and are more likely to die from the infection than people without MS.
 
The Study: With funding from the National MS Society, Drs. Katharine Whartenby, Justin Glenn and colleagues (Johns Hopkins University School of Medicine) investigated how the immune system changes when an infection such as influenza (flu) is coupled with the MS-like disease EAE in mice. For comparison, other mice had EAE alone or were infected with flu virus alone. All mice with EAE alone or with flu virus alone survived, but 70% of mice with both EAE and the flu virus died. Mice with both EAE and flu virus could not clear the flu virus from their lungs, showed increased lung damage, and lost more body weight.
 
The researchers also found that mice with both EAE and flu had decreased numbers of immune cells in their lungs, and lower levels of molecules secreted by immune cells to help clear infection. Infection with flu alone led to expansion of anti-virus immune cells, but this did not occur in mice with EAE plus flu.
 
This study was supported in part by a National MS Society Research Grant to Dr. Whartenby and a Collaborative MS Research Center Grant to Dr. Peter Calabresi. The team published their results in The Journal of Experimental Medicine (published online January 5, 2017).
 
Next Steps: These results provide important clues for increasing our understanding of why people with MS experience more severe infections. The team is continuing to delve into the mechanisms that make people with MS are more vulnerable to infection. This work may lead to the development of guidance around the timing and use of vaccines to maximize their efficacy.

About Multiple Sclerosis

Multiple sclerosis is an unpredictable, often disabling disease of the central nervous system that disrupts the flow of information within the brain, and between the brain and body. Symptoms range from numbness and tingling to blindness and paralysis. The progress, severity and specific symptoms of MS in any one person cannot yet be predicted, but advances in research and treatment are leading to better understanding and moving us closer to a world free of MS. Most people with MS are diagnosed between the ages of 20 and 50, with at least two to three times more women than men being diagnosed with the disease. MS affects more than 2.3 million people worldwide.

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