Fig. 2: METTL3-deficient macrophages are more susceptible to M2 activation through the PI3K/AKT and JAK/STAT6 signaling, thereby accelerating allergic airway inflammation.

a CLs-liposome was i.p. administered in the clodronate group and PBS was administered in the control group. Flow cytometry analysis of the efficiency of macrophage depletion in BALF from Mettl3 KO mice by clodronate treatment (n = 5 animals). b Total and (c) differential BALF cell numbers from experimental asthmatic animals were analyzed by flow cytometry (n = 5 animals). d Histopathological changes in the lung tissues were examined by H&E- and PAS-staining. Scale bars: 200 μm and 100 μm, respectively. Inflammation and PAS scores were quantified (low panel) (n = 5 animals). e Heatmap illustrating the upregulated expression of M2 activation-associated genes in human THP1-derived macrophages transfected with METTL3 siRNA pools (200 nM), compared with negative control (NC) cells. f RT-qPCR analysis of M1 and M2-associated markers expression in WT and Mettl3 KO mice BMDMs (n = 3 animals) stimulated with LPS or IL-4, respectively. g ELISA shows the levels of TNF and IL-10 secretion in WT and Mettl3 KO mice BMDMs (n = 5 animals). h KEGG enrichment analysis shows the top pathways enriched in METTL3-deficient macrophages. i Western blot showing levels of AKT phosphorylation (p-AKT), AKT, STAT6, and p-STAT6 in WT and Mettl3 KO BMDMs (n = 3 animals), following IL-4 stimulation. Statistical analysis of the data was performed using two-sided unpaired t test (a, f, g, h), 1-way ANOVA (b, d), and 2-way ANOVA (c, i) followed by either Tukey’s or Sidak’s multiple comparison tests. Data are presented as means ± SEM from one of three independent experiments. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001; n.s, not significant.