Abstract Objective This study aims to investigate the inhibitory effects and underlying mechanisms of Sapylin on the progression of malignant pulmonary nodules, with a particular focus on its impact on natural killer (NK) cell function and the tumor immune microenvironment. Methods Orthotopic mouse models of early-stage malignant pulmonary nodules (KT model) were established using AdCre-induced genetic recombination in genetically engineered mice. Nodule development was dynamically monitored via micro-CT imaging. KT model mice were administered either Sapylin (0.1 KE/mL via nebulization, 15 minutes daily, in 28-day cycles) or PBS as a control. Tumor burden was assessed using micro-CT, histopathological examination (H&E staining), and survival analysis. Cell migration and invasion capabilities were evaluated using scratch wound assays, among other methods, alongside marker detection via flow cytometry and single-cell RNA sequencing. Results Sapylin treatment significantly inhibited the progression of malignant nodules and improved survival outcomes. It also suppressed tumor cell migration, invasion, and proliferation. Furthermore, Sapylin enhanced NK cell infiltration and modulated their phenotype, downregulating inhibitory receptors while upregulating activating receptors. Additionally, single-cell RNA sequencing and functional analyses indicated that Sapylin promoted NK cell effector functions. Gene set enrichment analysis identified key signaling pathways and regulatory networks associated with NK cell activation in the Sapylin-treated group. Conclusion Sapylin effectively inhibits the progression of malignant pulmonary nodules by directly suppressing tumor growth and metastasis and by reprogramming the immunosuppressive microenvironment, particularly through enhancing NK cell-mediated anti-tumor immunity. These findings highlight the potential of Sapylin as a promising immunotherapeutic agent for the treatment of malignant pulmonary nodules. This abstract is funded by: Noncommunicable Chronic Diseases-National Science and Technology Major Project (2024ZD0529300), National Natural Science Foundation of China (82570143, 82170110)
Yang et al. (Fri,) studied this question.