IL9 and Parkinson disease: Moreover, the regulatory role played by IL-9 in human inflammatory macrophages within the CNS, could be relevant in other CNS disorders, including neurodegenerative diseases, such as Alzheimer, Parkinson, and amyotrophic lateral sclerosis diseases [35], where even if the pathological processes are not primarily inflammatory driven, mononuclear phagocytes are known to contribute to the development of pathology.