Common Flu Virus Could Lead to Muscle Wasting in DMD, Preclinical Study Suggests

Infection by the influenza virus, commonly known as the flu, was found to contribute to muscle degeneration in a zebrafish model of Duchenne muscular dystrophy (DMD). Scientists often use zebrafish in research due to their genetic structure, which is similar to that of humans.

The findings were reported in the study, “Influenza A Virus Infection Damages Zebrafish Skeletal Muscle and Exacerbates Disease in Zebrafish Modeling Duchenne Muscular Dystrophy,” which appeared in the journal PLOS Currents Muscular Dystrophy.

The study suggests that flu vaccination could be important for patients with genetic muscle diseases, and for other illnesses in which the immune system, inflammation, and muscle tissues are known to be affected.

Influenza viruses are responsible for the most common infection characterized by muscle pain and weakness. However, little is known about the impact the virus has on muscle tissue and how it causes muscle damage.

Analysis of muscle tissue biopsies collected from patients with muscle complications due to influenza infection and from patients with genetic muscular diseases showed similar tissue damage patterns and expression of biomarkers. This suggested that both influenza infection and genetic muscular diseases may rely on the same molecular mechanism.

To add new insight, a research team at the University of Maine evaluated the effect of the influenza virus in an experimental model of DMD, the most common genetic muscular disorder.

The team used zebrafish that had a variant version of the DMD gene, which is similar to human DMD. Researchers injected the influenza A virus into the bloodstream of the fish. Within 24 hours, the fish showed signs of infection, swollen hearts, reduced mobility, and body trembling.

Analysis of zebrafish muscle tissue confirmed that the virus could directly infect muscle cells and damage them. But researchers also observed that the infected DMD fish had more severe muscle tissue damage than those that were not infected by influenza virus.

Additionally, they found that the virus’s presence in the muscles induced a pro-inflammatory network of signals and it recruited immune cells to the site of damage. This process also may be responsible for tissue damage and could be linked to DMD’s progressive debilitation.

Overall, the study contributes to the understanding of how the influenza virus affects muscles, and it identifies patient populations that may be at risk for poorer outcomes caused by the flu.

“Our results suggest that anti-influenza vaccines and other precautionary measures to prevent this infectious disease and the activation of the inflammatory immune response in people (especially those with genetic muscle diseases) is a very important endeavor not just to protect against pulmonary complications of IAV [influenza] infection, but skeletal muscle damage as well,” the researchers wrote.

The study was supported by the National Institutes of Health, the March of Dimes, and the National Institute of Child Health and Human Development.