The evidence so far suggest that the microglia will respond to the changes in neurons during PD, it will not only sense changes in neurotransmitter release and or modifications in other proteins expressed by neurons such as CD200 or CX3CL1 (Ransohoff and Cardona, 2010), but it will also recognize and respond to a-syn. Here, CX3CL1 is linked to Parkinson disease.