Extended Data Fig. 6: Microglia diversity analysis demonstrates the absence of CHIT1-positive microglia in mouse spinal cord and primate brain.
From: CHIT1-positive microglia drive motor neuron ageing in the primate spinal cord
a, Immunofluorescence staining for CHIT1, NeuN and IBA1 in GM and WM regions from young and aged monkey frontal lobes. n = 8 monkeys per group. Similar results were found in three discontinuous slices of coronal sections per monkey. Each slice contained intact grey matter structures and a portion of the white matter, within an area of 15 mm2. Scale bars, 100 μm. GM, grey matter. WM, white matter. b, Immunofluorescence staining for CHIT1 and IBA1 in the spinal cords from 2-, 13-, and 29-month-old C57BL/6 mice. n = 8 mice per group. Similar results were found in three discontinuous cross-sectional slices per mouse. Scale bars, 50 μm. c, Single-nucleus transcriptomic atlas of young and aged mouse spinal cords coloured by cell type (top) and age group (bottom). Ttn+, Ttn-positive cells. d, Dot plot showing the expression of marker genes of different cell types in mouse spinal cord. e, t-SNE plots showing the distribution of microglia in the mouse spinal cords. Upper, predicted microglia 3 is highlighted in red. Bottom, the points are coloured by age. f, Expression levels of the indicated genes. Top, expression levels of Chit1, Gpnmb, and Lgals3 in total microglia of mouse spinal cords. Bottom, expression levels of these three genes in both young and aged microglia of mouse spinal cords. g, Venn diagram showing the overlapped genes between the top 50 marker genes of microglia 3 in monkey spinal cord and predicted microglia 3 in mouse spinal cord. h, Heatmap showing the enriched pathways of marker genes for microglia 3 in monkey and mouse spinal cords. i, t-SNE plots showing the clusters and expression levels of P2RY12 and CHIT1 in the indicated datasets of myeloid cells, coloured by cluster (left) and expression level (right). j, Venn diagram showing the shared genes between core transcriptomic signatures of aging and neurodegenerative microglia and marker genes of microglia 3 of monkey spinal cord. k, ELISA analysis of CHIT1 concentration in young and aged human CSF and serum. Schematic diagram (top) and quantification for CHIT1 concentration in human CSF and serum (bottom) are shown. P values were calculated using two-tailed unpaired t-tests. Three biological replicates per individual. CSF, n = 3 individuals per group; serum, n = 40 individuals per group.
