Immune response during idiopathic Parkinson's disease: From humans to animal models

Data obtained from animal models, patient studies, and population genetic analyses support a relevant role for the immune system in idiopathic Parkinson's disease (PD). For years, the investigation of the immune response in PD was focused on the microglia event, disregarding the possible intervention of other immune cells. However, studies addressing the role of nonmicroglia immune cells have recently accumulated and revealed that the disease also includes changes in peripheral immune cells. This has gained relevance, as the concept of a widespread alpha-synuclein pathology and degeneration has emerged, redefining PD as a disease of the central and peripheral nervous systems. In this chapter, we revise the evidence of early immune changes in PD and their time evolution. We describe the relevance of alpha-synuclein in the immune response and its ability to initiate inflammation. We also examine the evidence of the involvement of innate and adaptive immune cells in inflammatory and degenerative events. Finally, we shortly considered the possible therapeutic avenues opened based on the current knowledge.