Fig. 5

The Exo-ER upregulate the macrophage PD-L1 expression and induce macrophage polarization toward the M2 subtype in vivo. Exosomes were isolated from the culture media of HN4 cells treated with IFN-γ, PD-L1 siRNA (Exo-ER-siPD-L1), or NC siRNA (Exo-ER-siNC). Then, the Exo-ER, Exo-Con, Exo-ER-siNC, or Exo-ER-siPD-L1 (30 μg/mouse) were injected into six-week-old female nude mice through the tail vein. The peritoneal macrophages were isolated, and the expression of PD-L1 was evaluated using the qRT-PCR (A) and western blot (B) analyses (n = 2–3). C Quantification of PD-L1 protein levels in panel (B). D and E Relative CD163 (D) and CD206 M2 macrophage markers (E) mRNA expression in the isolated peritoneal macrophages (n = 3). F and G The ratio of M2 macrophage markers (CD163) and M1 macrophage markers (CD86 and iNOS) was shown in the isolated peritoneal macrophages (n = 3). H Immunofluorescence staining of CD68, CD163, and CD11c in OSCC tissues (TT) of patients with OSCC (scale bar = 50 μm) (n = 2–3). I Quantification of the CD68 + CD163 + cells (M2 macrophages) and CD68 + CD11c + cells (M1 macrophages) in (A) (*P < 0.05, **P < 0.01, and ***P < 0.001)