Elevated levels of interleukin-6 (IL-6) acting as pro-inflammatory cytokine, tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), and nitric oxide synthase (NOS), found in the SN, putamen, as well as in the cerebrospinal fluid (CSF) and serum of PD patients suggest that, in PD, glial cells acquire a pro-inflammatory phenotype (119). This evidence concerns the gene NOS1 and Parkinson disease.