CHRNA7 and Parkinson disease: The fact that α7 nAChR was expressed also in cells of the immune system has often been undervalued, in spite of α7 nAChR stimulation that can result in the reduction of inflammation, leukocytes extravasation, lymphocyte proliferation, and macrophage and microglia activation ameliorating the disease processes of multiple sclerosis, Alzheimer’s, and Parkinson’s disease.