Inflammation in Parkinson's disease.

Parkinson's disease (PD) is a common neurodegenerative disease that is characterized by the degeneration of dopaminergic neurons in the substantia nigra pars compacta. Inflammatory responses manifested by glial reactions, T cell infiltration, and increased expression of inflammatory cytokines, as well as other toxic mediators derived from activated glial cells, are currently recognized as prominent features of PD. The consistent findings obtained by various animal models of PD suggest that neuroinflammation is an important contributor to the pathogenesis of the disease and may further propel the progressive loss of nigral dopaminergic neurons. Furthermore, although it may not be the primary cause of PD, additional epidemiological, genetic, pharmacological, and imaging evidence support the proposal that inflammatory processes in this specific brain region are crucial for disease progression. Recent in vitro studies, however, have suggested that activation of microglia and subsequently astrocytes via mediators released by injured dopaminergic neurons is involved. However, additional in vivo experiments are needed for a deeper understanding of the mechanisms involved in PD pathogenesis. Further insight on the mechanisms of inflammation in PD will help to further develop alternative therapeutic strategies that will specifically and temporally target inflammatory processes without abrogating the potential benefits derived by neuroinflammation, such as tissue restoration.