Accordingly, studying the role of P. gingivalis and gingipains in the degeneration of SNpc dopaminergic neurons in PD animal models, such as the recently published oral P. gingivalis infection of LRRK2 R1441G mice7, will be important, along with controlled cellular studies such as P. gingivalis infection or P. gingivalis OMV invasion of neurons derived from human induced pluripotent stem cells59. Here, LRRK2 is linked to Parkinson disease.