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. 2022 Jan 1;12(2):512–529. doi: 10.7150/thno.64033

Figure 5.

Figure 5

Protracted harmful effects of monocytic infiltrates after LPS/HI brain injury. (A) Volcano plot of differentially expressed genes (DEGs) between monocytic derivatives in the 2 d post LPS/HI blood (left) and brain (right), based on TRAP-based RNA-sequencing in tamoxifen-doses CCR2-CreER; R26R-EGFP/Rpl10A mouse neonates. The vertical dash-lines indicate ± 2-fold change, and the horizonal dash-line denotes p < 0.05. Selected marker genes for monocytes (green) and microglia (red) were labeled. (B) The z-score display of selected monocyte or microglia marker gene expression in the blood or post-LPS/HI brain. Note the expression of monocytic genes (CCR2, Lyz2, Ly6C, and CD11b) were reduced, while the microglia marker genes (Sall1, Ms4a7, and Tmem119) were up-regulated in 2 d and 14 d post-LPS/HI brain. (C-E) Double-labeling showed more specific expression of Tmem119 (C) and Sall1 mRNA (D) in 30 d post-LPS/HI CCR2-CreER; R26R-GFP mouse brain. At 5 m post-LPS/HI (E), amoeboid GFP+ derivatives expressed MHC-II, TNFα, and microglial markers (Tmem119 and P2RY12). (F-G) At 30 d post-LPS/HI, the ipsilateral hippocampus contained more TUNEL+/NeuN+ double-positive nuclei, mostly surrounded by GFP+ monocytic infiltrates (arrows), than the contralateral counterpart (p = 0.02 by unpaired t-test). (H-I) Similarly, the ipsilateral hippocampus showed significant reduction of anti-PSD-95+ (p = 0.035) and colocalized anti-synaptotagmin (Syn)+/anti-PSD-95+ puncta (p = 0.01), but not anti-Syn+ puncta (p = 0.06), than contralateral hippocampus at 30 d after LPS/HI injury. Note the area harboring GFP+ monocytic derivatives (marked by dash-line) showed the greatest reduction of anti-Syn and anti-PSD-95 signals. N = 4 mice per group in A-B. N = 3 for each time point in C-I. Results are displayed as the mean ± SEM. Statistics are performed as unpaired t-test (G and I). Scale bar: 50 μm.