Single-cell RNA-sequencing analysis reveals cellular states and intercellular communication of human lumbar facet-joint degeneration

Figure 4 Identification of macrophage subpopulations and their marker-gene expression in different degeneration grades of the human lumbar facet joint. A: Uniform Manifold Approximation and Projection plot showing the single-cell transcriptomic landscape of macrophages. Five subclusters were identified. Numbers 1-5 represent Mφ-F13A1, Mφ-TCN2, Mφ-COL27A1, Mφ-CD52, and Mφ-IL3RA, respectively; B: Dotplot of top ten marker genes for five macrophage subclusters (defined in A); C: Violin plot of representative genes of macrophage subclusters (defined in A); D: Representative immunohistochemistry staining of CD68 of macrophage subclusters in different degenerated lumbar facet joint cartilage samples. Scale bar 100 μm; E: Gene enrichment for these subclusters (defined in A) in comparisons with the classical cell type M1 and M2 macrophage. Bubble size represents the proportion of upregulated and downregulated genes of subclusters based on the gene signature on the X axis. The color of the circle represents the directional false discovery rate. Red, enrichment of upregulated genes in the specific cell subsets; blue, depletion of downregulated genes.