PROS1 and Parkinson disease: However, excessive microglial inflammation is capable of inducing collateral neuronal damage through over-production of pro-inflammatory factors such as the pro-apoptotic protein tumour necrosis factor (TNF)-α, reactive oxygen species (ROS) and nitric oxide (NO), and is implicated in the chronic neuronal death seen in neurodegenerative diseases such as Parkinson’s disease (PD) and Alzheimer’s disease21, 22, 23.