SERPINE1 Promotes Lung Cancer Immunosuppressive Microenvironment and Resistance to Anti-PD-1 Therapy by Upregulating M2 Macrophages

Co-culture systems of lung cancer cells with human monocyte-derived macrophages, and triple co-culture systems of lung cancer cells, macrophages and CD8⁺ T cells were established. The expression of SERPINE1 was detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting.

The expression of M2 macrophage polarization markers (CD163, CD206) was measured by flow cytometry and immunofluorescence. The levels of immunosuppressive cytokines (IL-10, TGF-β, Arg-1) in the culture supernatant were determined by enzyme-linked immunosorbent assay (ELISA). The proliferation of CD8⁺ T cells was evaluated by carboxyfluorescein succinimidyl ester (CFSE) labeling, and the expression of T cell cytotoxic molecules (Granzyme B, IFN-γ) was detected by flow cytometry.