SNCA and Parkinson disease: Moreover, as revealed in Thome et al.'s study, microRNA-155 (miR-155) was significantly upregulated in an in vivo model of PD (developed using adeno-associated virus-mediated expression of alpha-synuclein); they also found that without miR-155, the mouse model experienced reduced proinflammatory responses to alpha-synuclein blocked alpha-synuclein-induced neurodegeneration.