Seasonal Flu Infection May Increase Risk of Parkinson's
Recent study has provided further evidence supporting the idea that environmental factors, incluidng influenza may be involved in Parkinson's disease.
A new study has found the risk of developing Parkinson's Disease is higher in people who have been infected with the seasonal flu. Researchers suspect a particular strain of influenza is responsible for predisposing lab mice to develop disease processes that closely mimic Parkinson's Disease. There is no known cause for Parkinson's as researchers continue their efforts to find contributing factors that trigger the disease. The study was published in the journal npj Parkinson’s Disease.
Viruses in Mice Create Parkinson's Symptoms
According to Professor Richard J. Smeyne, the study showed more evidence that influenza and environmental factors play a role in the development of Parkinson's Disease. Researchers demonstrated that when mice make a full recovery from the H1N1 influenza virus, they then become susceptible to chemicals that are known to activate Parkinson's (at least in the lab).
In previous studies, collaborators Dr. Smeyne and Dr. Stacey Schultz-Cherry showed that the deadly bird flu (H5N1) which has a 60% mortality rate, was able to create Parkinson's like symptoms in lab mice. The H5N1 virus travels to the brain via infection of nerve cells causing inflammation. If inflammation in the brain does not heal quickly as in this case or when a person suffers a trauma to the head, the result can lead to Parkinson's Disease.
Immune System Causes Inflammation
The new study builds on that work but uses the less lethal H1N1 virus (Swine Flu). The researchers showed that H1N1 makes the immune system release inflammatory chemicals called cytokines which cause inflammation in the brain. Using mice as models to test Parkinson's Disease, Dr. Smeyne used the toxin MPTP to induce symptoms of Parkinson's in two groups of mice.
The group that was infected with the H1N1 virus had more severe symptoms of Parkinson's then the other group of mice only exposed to the toxin. More importantly, the sensitivity to the toxin MPTP was eliminated when the mice were given H1N1 vaccinations or an antiviral medication like Tamiflu.
According to Dr. Smeyne, we are exposed to influenza on a yearly basis, and H1N1 belongs to a family of influenzas called "Type A". Although the testing has yet to go to clinical human trials, Smeyne believes their work justifies further investigation. Through seasonal flu vaccination or antiviral medications, we may become resilient to the toxic chemicals our immune systems will produce in response to H1N1 and other deadly viruses. This will allow us for a full recovery in less time without impacting our brain health in the long term.
Sadasivan, S., et al. Synergistic effects of influenza and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can be eliminated by the use of influenza therapeutics: experimental evidence for multi-hit hypothesis. npj Parkinson's Disease, 2017 DOI: 10.1038/s41531-017-0019-z