Eased expression of LRP1 was observed in PD brain (38) and functional soluble LRP1 was also detected in human brain tissue and CSF (39). Colony-stimulating factor receptor 1 (CSFR1) is the receptor for colony stimulating factor 1 and interleukin-34 (IL-34), which are key regulators of the monocyte/macrophage lineage (40). In a mouse model lacking CSFR1, neurons are more susceptible to cell death a