Blockade of purine metabolism reverses macrophage immunosuppression and enhances anti-tumor immunity in non-small cell lung cancer

Aims

Immune checkpoint blockade therapy is not effective in most patients with non-small cell lung cancer (NSCLC) due to the immunosuppressive tumor microenvironment. Macrophages are key components of tumor-infiltrating immune cells and play a critical role in immunosuppression, which can be mediated by cell-intrinsic metabolism. This study aimed to evaluate whether macrophages regulate NSCLC progression through metabolic crosstalk with cancer cells and affect immunotherapy efficacy.

Methods

The macrophage landscape of NSCLC tissues were analyzed by single-cell sequencing and verified through flow cytometry and immunofluorescence. Multiplex assay, single-cell sequencing data, ELISA, immunofluorescence, and RNA-seq et al. were used to investigate and verify the mechanism of macrophage-mediated metabolic regulation on immunosuppression. The tumor-bearing model was established in C57BL/6 J mice to explore in vivo efficacy.

Results

We found that tumor tissue-derived macrophages exhibited an anti-inflammatory phenotype and had a prognostic value for NSCLC. NSCLC cell-secreted CXCL8 recruited macrophages from peritumor tissues to tumor sites and promoted programmed death-ligand 1 (PD-L1) expression by activating purine metabolism with increasing xanthine dehydrogenase and uric acid production. Moreover, purine metabolism-mediated macrophage immunosuppression was dependent on NLRP3/caspase-1/IL-1β signaling. Blockade of purine metabolism signaling enhanced anti-tumor immunity and the efficacy of anti-PD-L1 therapy.

Conclusions

Collectively, our findings reveal a key role of purine metabolism in macrophage immunosuppression and suggest that blockade of purine metabolism combined with immune checkpoint blockade could provide synergistic effects in NSCLC treatment.