Furthermore, in Porphyromonas gingivalis (Pg)-treated leucine-rich repeat kinase 2 (LRRK2) R1441G mice, dopaminergic neurons in the SN were reduced, but serum IL-17A, brain IL-17 receptor A, and activated microglial cells were increased; these findings indicated that neuroinflammation might play an important role in the pathophysiology of LRRK2-associated PD [130]. Here, IL17A is linked to Parkinson disease.