CCL2 and Parkinson disease: Like other neurodegenerative diseases, PD also involves elevated levels of proinflammatory cytokines monocyte chemoattractant protein-1 (MCP-1), CCL-5, macrophage inflammatory protein-1α (MIP-1α), IL-8, interferon-gamma (IFNγ), IL-1β, and TNFα [24].