Fig 2: Immunofluorescence staining for IBA1 and TMEM119 in microglia and for GFAP in astrocytes. (A) The results are expressed as mean ± S.D. NC NW: Normal Chow Normal Water; WD SW: Western Diet Sugar Water. T0: 0 weeks; T2: 8 weeks; T4: 28 weeks. IBA1: Ionized calcium-binding adaptor molecule 1, TMEM119: Transmembrane protein 119, GFAP: Glial fibrillary acidic protein. *: p < 0.05, **: p < 0.01, ***: p < 0.001 vs NC NW T4; #: p < 0.05, ##: p < 0.01, ###: p < 0.001 vs WD SW T2, °: p < 0.05, °°: p < 0.01, °°°: p < 0.001 vs WD SW T0; ^: p < 0.05, ^^: p < 0.01 vs NC NW T0. (B) Representative confocal images of IBA1 positive microglia (above), TMEM119 positive microglia (middle), GFAP positive astrocytes (below) and magnified illustrations of microglia and astrocytes morphology.

Fig 3: Ifnar1−/− knockout rescues Rnaset2−/− related neuropathology.a Immunohistochemistry of rescued cerebral T cell infiltration (CD3), interferon-stimulated gene 15 (ISG15) upregulation, microglial activation (TMEM119), and macrophages/activated microglia infiltration (MAC3) in Rnaset2−/− Ifnar1−/− mouse brain sections compared to control mouse and Rnaset2−/− mouse brain sections. Scale bar, 20 µM and 1 mm for whole slices of ISG15. b Rescued cerebral inflammatory infiltration of CD3+ and MAC3+ cell densities determined in whole brain slices, TMEM119+ cell density of representative cortical regions, and % of immunoreactive area for ISG15 in Rnaset2−/−Ifnar1−/− (n = 6) compared to control (n = 5) and Rnaset2−/− (n = 5). Images in a are representative for the 5–6 animals analyzed for each genotype. c T2 relaxation time measurement in various brain regions of Rnaset2−/−Ifnar1−/− (n = 5), compared to control (n = 8) and Rnaset2−/− (n = 8). For regions of interest (ROI) 1–4 selected for T2 relaxation time measurements see Fig. 5d. IFNAR1-deficiency resolved extension of T2 relaxation in Rnaset2−/− mice. Data of two independent experiments. d Representative magnetic resonance anatomical images in axial plane showing ventricular enlargement in Rnaset2−/− mice but not in Rnaset2−/−Ifnar1−/− mice due to shrinkage of the hippocampus on both sides (arrows). e Percent area of hippocampus (left and right) with respect to whole brain area of Rnaset2−/− (n = 8), control (n = 8) and Rnaset2−/− Ifnar1−/− (n = 6). Data depicted as the mean ± SEM. p values of one-way ANOVA are represented as ****p < 0.0001, ***p < 0.001, **p < 0.01, *p < 0.05 and not significant (ns) p ≥ 0.05. MRI data from Rnaset2−/− and control mice are also depicted in Fig. 5c and d. Source data are provided as a Source data file.

Fig 4: Double immunostaining of dopaminergic neurons with microglia or astrocyte. GFAP was used as the biomarker of astrocyte, while Iba-1 and Tmem119 were used to mark the microglia. Panels a, c and e depict double immunostaining of TH with activated GFAP, Iba-1 or Tmem119 respectively. Activated glial cells are labeled with Cy3 (red), and the DA neurons are stained green in the control (NS), model (M or MPTP) and JJDHYZ-H (JH) groups. Images were first observed with ×100 magnification (A–K); D, H and L are enlargements of the rectangular areas marked in C, G and K. Few activated astrocytes and microglia were observed in the control and JJDHYZ-H groups, while MPTP promoted an increase in the number of these cells (P <0.001). Histograms showing the number of GFAP-positive cells are presented in panel b. Bar graphs of Iba-1-positive cells and Tmem119-positve cells are presented in panel d and f. ☆P <0.05, ◇P <0.01 vs. the control group; ★P <0.05, ⬩P <0.01 vs. the MPTP group.

Fig 5: Representative images of neocortex sections from naïve (a, d, g), EAE-affected (b, e, h; cs 1.5, 2.0, 2.5, respectively), and EAE-affected MSC-treated (c, f, i; cs 1.0, 1.5, 2.0, respectively) mice, sacrificed at 6 h (a–c), 24 h (d–f), and 10 days (g–i) after MSC treatment, double immunostained for TMEM119 and CCL2. a, d, g In naïve mice, the typical delicate morphology of surveillant microglia is revealed by TMEM119 staining of cell bodies (arrows) and processes (arrowheads). b, e, h In EAE mice, TMEM119 is extensively colocalized with CCL2 on hypertrophic microglial cells, with the chemokine staining largely prevailing on cell bodies and processes (yellowish/reddish fluorescence; arrows). c, f, i Microglia hypertrophy and CCL2 staining are reduced on microglia of EAE-affected MSC-treated mice, with reduced cell points of CCL2/TMEM119 colocalization (yellowish fluorescence) and a prevailing TMEM119 staining (green fluorescence; arrows); note in (i) TMEM119-positive microglia processes that surround the wall of a cortex microvessel (V, arrowheads). TOPRO-3 nuclear counterstaining. Scale bars: a–i 20 µm