Oral Bacteria In Gut May Trigger Parkinson’s, Study Finds

Oral microbes that settle in the gut may influence brain cells and play a role in triggering Parkinson’s disease, a new study has found.

Scientists at the Pohang University of Science and Technology in South Korea uncovered how chemical compounds made by oral bacteria in the gut could contribute to the onset of the neurological disorder, which is marked by tremors, rigidity, and slowed movements.

“Our study provides a mechanistic understanding of how oral microbes in the gut can influence the brain and contribute to the development of Parkinson’s disease,” stated Professor Ara Koh. “It highlights the potential of targeting the gut microbiota as a therapeutic strategy, offering a new direction for Parkinson’s treatment.”

Earlier studies had shown that the gut bacteria of Parkinson’s patients differ from those of healthy individuals. However, the exact organisms and their by-products remained uncertain.

The latest findings, published in Nature Communications, identified higher levels of Streptococcus mutans in the gut of Parkinson’s patients. This oral bacterium commonly causes tooth decay.

The study showed that S mutans produces an enzyme called urocanate reductase (UrdA) and a metabolite, imidazole propionate (ImP).

Both were present at elevated levels in the gut and bloodstream of patients.

Crucially, ImP was able to circulate through the body, reach the brain, and damage dopamine-producing neurons.

In mouse experiments, scientists introduced S mutans into the gut or engineered E coli to produce UrdA.

These mice displayed raised ImP levels in blood and brain tissue, along with Parkinson’s-like signs such as neuronal loss, motor impairment, neuroinflammation, and greater build-up of alpha-synuclein, a key protein linked to the disease.

The harmful effects relied on activation of the protein complex mTORC1.

Treating mice with a mTORC1 inhibitor markedly reduced inflammation, neuronal damage, protein aggregation, and motor problems.

The results suggest that addressing the oral-gut microbiome and its metabolites could provide fresh approaches to tackling Parkinson’s disease.

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