The role of abnormally activated microglia in the pathogenesis of Parkinson's disease and its potential clinical application

Parkinson's disease (PD) is a neurodegenerative disorder which usually affects old-aged people, and the mechanism underling the disease still remains unknown. Recent studies have suggested that abnormally activated microglia plays an important role in the pathogenesis of the disease. Several stimuli, such as α-synuclein, neurotoxins, aging, as well as attenuated or deficient inhibiting signals of endogenous CD200-CD200R can cause the abnormal activation of microglia, which will result in dopaminergic neuron injuries through secreting pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), activating inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and nicotinamide adenine dinucleotide phosphate oxidase-2 (NOX-2). Therefore, it may be a novel way for PD therapy to inhibit neuroinflammatory injuries by suppressing the abnormal activation of microglia.