IL1B and Parkinson disease: Mice studies based on the injection of LPS or the adenovirus expressing IL-1 into the SN, which had been previously exposed to 6-hydroxydopamine (6-OHDA)—a neurotoxin that is commonly used to induce PD—led to the activation of microglia towards a pro-inflammatory phenotype, increasing IL-1β secretion and the chemokine MCP-1 and decreasing the anti-inflammatory cytokine levels of IL-4.