Might a Gut Infection Be the Precursor to Parkinson’s Disease?

Scientists in Montreal published a study this week detailing that an infection in the gut could lead to a pathology that very closely resembles Parkinson’s disease, in a mouse model absent one gene that it linked to the human form of the disease. The discovery builds on previous studies, from the same group, suggesting that Parkinson’s disease might, in fact, have a major immune component. This, they say, could offer new ways to develop therapeutic strategies. 

The researchers confide that understanding Parkinson’s disease is more important than ever.  The number of patients, around the world, more than doubled between 1990 and 2016, from 2.5 million to 6.1 million.  Conservatively, experts projected yet another doubling of these numbers over the next to 30 years, to yield more than 12 million PD patients, globally, by 2050.

That said, data shows roughly 10 percent of PD cases are the result of genetic mutation, specifically within the PINK1 and Parkin proteins.  These proteins have been linked to mitochondria health but starting at a notably younger age.  In mouse models, though, the same mutations did not generate symptoms of the disease and this has led researchers to conclude mice may not be the right subject for studying PD. 

This study was a collaboration between scientists at Universite de Montreal—led by Michel Desjardins and Louis-Eric Trudeau—and the Montreal Neurological Institute—led by Heidi McBride—and McGill University—led by Samantha Gruenheid.   

Trudeau and McBride, in particular, are specialists in Parkinson’s disease research and they argue the disparity between human and mice models resides in the fact that [lab] mice tend to live in mostly germ-free, environmentally-controlled facilities.  These conditions, of course, do not effectively represent the same environment that humans are exposed to, particularly regarding exposure to infectious microorganisms.   

A neuroscientists, Trudeau explains, “Most of the current models of PD are based on the belief that neurons die due to toxic elements accumulating inside them. This does not explain, however, the fact that PD pathology is initiated in patients several years before the emergence of the motor impairment and any noticeable loss of neurons.”

Gruenheid is a microbiologist who remains confident in the link between infection and PD.  In fact, she asserts that more study of the link between immune response and Parkinson’s disease initiation will allow them to further develop and test new therapeutic approaches. 

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