IL1A and Parkinson disease: Based on our results, we propose that neuronal-glial interactions give rise to co-stimulation of expression and release of sAPPα from neurons and excessive expression of IL-1 in activated microglia and that these interactions are key links in an array of self-propagating, molecular and cellular interactions that are neurodegenerative in nature, triggering the overlapping clinicopathological spectrums of AD, LBD, and PD.