Microbes and Parkinson's disease: from associations to mechanisms.

Parkinson's disease (PD) is a neurodegenerative disorder influenced by both genetic and environmental factors. The mechanisms leading to neurodegeneration in PD are still under investigation, with several mechanistic models currently proposed. A number of microorganisms have been associated with increased risk of PD in humans, and recent research using newly developed models has begun to elucidate how these microbes may factor into disease development. Newly identified roles for PD-associated genes in host-microbe interactions and response to infections have also recently been uncovered, providing further evidence for microbial contributions to PD. Here we summarize these recent advances in the field and discuss them in the context of both historical and emerging hypotheses for PD development, with a particular focus on the application of rodent models as systems allowing for mechanistic hypothesis testing.