Single-cell RNA sequencing analysis revealed cellular and molecular immune profiles in lung squamous cell carcinoma

Although breakthroughs have been made in the treatment of non-small cell lung cancer, there are only a few choices for advanced-stage or recurrent lung squamous cell carcinoma (LUSC) patients. In our study, we identified 7 major cell types in thedepicted the immunolandscape of LUSC microenvironment using single-cell RNA sequencing. We found that an immunosuppressive receptor, T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT), was highly expressed by regulatory T cells (Tregs) and exhausted CD8⁺T cells, suggesting that upregulation of TIGIT might promote an immunosuppressive microenvironment and inhibit the cytotoxic ability of CD8⁺T cells. We also identified tumor-associated neutrophil (TAN), characterized by CXCR2, CSF3R and CXCL8, in the tumor region, and TANs upregulated the expression of interleukin 1 receptor antagonist (IL1RN) which suggested that TAN might exert an immunosuppressive role via expressing IL1RN. Furthermore, the number of SPP1+ macrophages(SPP1⁺M) significantly increased in tumor microenvirnment, which was correlated with the poor survival of patients. Additionally, regulatory networks based on SPP1⁺M revealed that the disparities of several ligand-receptor pairs existed between tumor and normal tissues. Among these pairs, SPP1-CD44 showed the most interactions between SPP1⁺M and other cell types. Our results provided deep insight into the immune landscape of LUSC and an essential resource for drug discovery in the future.