CX3CR1 and nervous system disorder: Specifically the interaction between microglial CX3CR1 and CX3CL1 expressed by neurons regulates microglial activation and cross talk between neurons and glia in several neurological diseases [25,48,49] like Tau pathology [50], Alzheimer’s Diseases (AD) [51], Multiple Sclerosis (MS)[52], Amyotrophic Lateral Sclerosis (ALS)[53,54], and HIV-induced encephalitis [55].