May 30, 2017
Dealing with a seasonal flu infection is nothing short of a nightmare in the short term, but could coming down with the flu also pose a risk for the long-term development of Parkinson's disease?
Neuroscientists and infectious disease experts at Thomas Jefferson University Hospital believe they may have found a potential clue to the mystery surrounding Parkinson's, the prevalent degenerative condition whose causes remain largely unknown.
While genetic factors, environmental toxins and oxidation have all been examined as triggers, there remains no scientific consensus on the underlying cause of Parkinson's patients' debilitating loss of nerve function, balance and coordination.
Led by the Jefferson research team, a new study published in npj Parkinson's Disease finds that a certain strain of influenza virus predisposes mice to developing pathologies similar to those seen in Parkinson's disease.
The research builds on a previous discovery that the deadly H5N1 influenza strain, commonly known as Bird Flu, has the capacity to infect the nerve cells and brains of mice. Inflammation in these mice later resulted in Parkinson's-like symptoms.
In the latest study, researchers looked at the less lethal H1N1 "swine flu." While they found no evidence of neuron infection in mice, there was still inflammation in the brain, likely caused by the chemicals released as immune cells fought the infection.
“This study has provided more evidence to support the idea that environmental factors, including influenza may be involved in Parkinson’s disease,” said neuroscientist Richard J. Smeyne, a leading researcher in the study. “Here we demonstrate that even mice who fully recover from the H1N1 influenza virus responsible for the previous pandemic are later more susceptible to chemical toxins known to trigger Parkinson’s in the lab.”
Long after the initial H1N1 infection, the study demonstrated that test mice had more severe Parkinson's symptoms than mice who never had the flu. Whenever mice were vaccinated against H1N1 or given antiviral medication at the time of the infection, their sensitivity to developmental complications was diminished.
The study relied on a model of the MPTP neurotoxin, the compound most associated with the destruction of dopamine-producing neurons in humans afflicted with Parkinson's disease.
“The H1N1 virus that we studied belongs to the family of Type A influenzas, which we are exposed to on a yearly basis,” Smeyne said. “Although the work presented here has yet to be replicated in humans, we believe it provides good reason to investigate this relationship further in light of the simple and potentially powerful impact that seasonal flu vaccination could have on long-term brain health.”