Fig. 9
B cell-derived IL-10 is a key regulator of pro-inflammatory responses in infiltrating monocytes/macrophages at the site of injury. A Animals treated with either WT or IL-10−/− B cells (N = 6/group) and subjected to CCI showed no difference in the overall numbers of infiltrating myeloid immune cells in the ipsilateral hemisphere 48 h after injury. B Assessment of the cytokine response in Ly6C+CD11b+ classical monocytes showed a significantly higher proportion of cells that were positive for the pro-inflammatory markers TNFα, IL-2, and IL-6 in the absence of IL-10 in the exogenous B cells. C Similarly, in Ly6C−CD11b+ non-classical monocytes, the proportion of cells positive for TNFα and IL-6, but not other cytokines, was significantly increased in animals treated with IL-10−/− B cells. D Among infiltrating neutrophils, TNFα-expressing cells were proportionally enriched in CCI injured hemispheres that received IL-10−/− B cells. E In animals treated with IL-10−/− B cells (N = 8–9/group) and subjected to CCI, phenotypic changes in infiltrating Ly6C+CD11b+ classical monocytes included a significant reduction in regulatory markers CD163, CD39, and CX3CR1, but also in the activation marker CD68. F In Ly6C−CD11b+ non-classical monocytes, the proportion of cells positive for CD39, CX3CR1, and PD-L1 decreased while Siglec F increased significantly. G The proportion of Siglec F positive cells among infiltrating neutrophils increased significantly when IL-10−/− B cells were applied. Statistical significance was assessed by two-way ANOVA and multiple two-tailed unpaired t-tests for each individual marker and corrected for multiple comparisons using the Holm-Å Ãdák method. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001