Interestingly, in PD patients, human leucocyte antigen-DR-positive microglia increases, as well as increases in tumor necrosis factor-alpha (TNF)-α, interleukin-1 beta (IL1-β), interleukin 6 (IL-6), inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX)2 in the striatum and the SNc, being the first evidence of the participation of inflammatory pathways in disease pathogenesis [55]. Here, NOS2 is linked to Parkinson disease.