Altering the microglia activation state using a pro-inflammatory versus anti-inflammatory environment. a Experimental time line for the α-syn cell-to-cell transfer model. b Grafted neurons positive for TH survived all three experimental conditions (left column of images; scale bars, 100 μm). The contrast in microglial morphology using immunohistochemistry for Iba-1 between the contralateral and ipsilateral striatum (right two column of images). The inset images are of the ipsilateral striatum indicating microgliosis around the graft and where the larger images are taken from; scale bars, 10 μm and 500 μm c Ipsilateral microglial morphology as assessed by the area:perimeter index (hydraulic radius). The horizontal line represents the mean area:perimeter index score of microglia from the contralateral striatum. Microglia in the LPS group had significantly higher area:perimeter index than the control. Area:perimeter index was significantly different between control and IL-4 (control, n = 20; LPS, n = 20; IL-4, n = 23; p < 0.05). d There was no significant difference in the density of microglia from the ipsilateral striatum between control, LPS-, or IL-4-injected mice. e Inflammatory cytokines measured using the MesoScale pro-inflammatory panel 1 assay in graft tissue and f in striatal tissue; control, n = 10; LPS, n = 8–12; IL-4, n = 12. * = p < 0.05, ** = p < 0.01, *** = p < 0.001. The error bars represent S.E.M.