IL-6 trans-signaling is a proinflammatory pathway known to induce reactive astrogliosis in the brain and is associated with the pathophysiology of central nervous system (CNS) injury, stroke, and neurodegenerative diseases such as AD and Parkinson's disease [reviewed by Garcia-Juarez and Camacho-Morales and Erta et al. (51, 52)]. This evidence concerns the gene IL6 and Parkinson disease.