Fig. 4

Mouse microglia underwent inflammatory activation in response to ACP cystic fluid and acted on neurons. A The number of cluster 11 microglia in the cystic fluid group was far greater than that in the sham operation group. B Pseudotime diagram of microglia. A darker color represents the default initial cell point. Microglia gradually differentiated in two directions from the cluster 7. The red line represents the trajectory corresponding to the development of cell fate 1, and the blue line represents the trajectory corresponding to the development of cell fate 2. The developmental trajectory of cell fate 1 is mainly contributed by cluster 11. C Branch point 1 to the left corresponds to cell fate 2, and branch point 1 to the downward corresponds to cell fate 1. The developmental trajectory of cell fate 1 is mainly contributed by the microglia of the cyst fluid group. D Monocle2's BEAM function was used to analyze the difference of the cells in the two fate stages before and after differentiation at branch point 1, and a heatmap of the differentially enriched genes was drawn to obtain 3 clusters. The GO enrichment analysis showed that the microglia in the developmental trajectory of cell fate 1 mainly exhibit inflammatory activation, increased synthesis of proinflammatory factors, activation of inflammation-related pathways, stimulation of lipoprotein particles, and increased synthesis and response of beta-amyloid (Aβ). E The expression of APOE, CD74, H2-Eb1, H2-Aa, and H2-Ab1 genes in the microglia of the developmental trajectory of cell fate1 was upregulated, and the upregulation of these genes was mostly contributed by the cyst fluid group. F The intercellular interaction of CD74–App and CD74–COPA was significantly strengthened between neurons of the ARC (cluster 3) and microglia (cluster 11) from the developmental trajectory of cell fate 1. In the interaction relationship, cluster 11 expressed the ligand gene CD74, and cluster 3 expressed the receptor genes APP and COPA