CCL2 and Parkinson disease: As an example, the chemokine monocyte chemoattractant protein 1 (MCP1/CCL2) is important for regulating the infiltration of monocytes into brain tissue in response to α-synuclein in mice [16] and increased levels of CCL2 in CSF [126] and plasma [127] are associated with the progression/prediction of PD motor symptoms.