Melatonin Suppresses Macrophage M1 Polarization and ROS-Mediated Pyroptosis via Activating ApoE/LDLR Pathway in Influenza A-Induced Acute Lung Injury

Figure 4

The blocking of the ApoE/LDLR pathway suppressed the regulation of macrophage polarization by melatonin. (a) Western blot images of the expression of ApoE, LDLR, iNOS, and Arg1 to β-actin in lung tissue homogenate of WT and ApoE-/- mice from the control (PBS) group, H3N2 infection group, and H3N2+Mel group. (b) Representative immunohistochemistry images of WT and ApoE-/- mouse lung tissues stained with iNOS and Arg1 as indicated by the brown staining (black arrows) from the control (PBS) group, H3N2 infection group, and H3N2+Mel group, bar 50 μm (original magnification ×50, ×400). Quantitative RT-PCR measurements of the relative mRNA levels of TNF-α (c), MCP1 (d), Arg1 (e), and Fizz1 (f) in lung tissues of WT and ApoE-/- mice. (g) Gating strategy of flow cytometry analysis to identify alveolar macrophages (AMs) (CD45+Siglec-F+CD11c+) as well as the M1 (CD86+) and M2 (CD206+) phenotypes of AMs in BALF. Individual percentages of AMs (h) in total leukocytes of BALF, CD86+ AMs (i), and CD206+ AMs (j) in total AMs in WT and ApoE-/- mice from the control (PBS) group, H3N2 infection group, and H3N2+Mel group. Data expressed as (). , , and compared with influenza A- (H3N2-) infected mice.

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