ObjectiveTo investigate the suppressive effect of 23-hydroxybetulinic acid （23-HBA）， a key constituent of Pulsatillae Radix， on the pulmonary inflammation-related carcinogenesis induced by the combined exposure of 4-（methylnitrosamino）-1-（3-pyridyl）-1-butanone （NNK） and lipopolysaccharide （LPS） in mice， alongside exploring its influence on immune cells and delving into the underlying mechanisms. MethodsA murine model of pulmonary inflammation-related carcinogenesis induced by NNK combined with LPS was established. Mice were randomly assigned into blank control， model， aspirin （10 mg·kg^-1）， and low-， medium-， and high-dose （3.75， 7.5， 15 mg·kg^-1， respectively） 23-HBA groups. The treatment lasted for 26 weeks， after which the spleen， lung， and peripheral blood samples were collected. Lung and spleen indices were calculated. Histopathological changes in the lung tissue were observed by hematoxylin-eosin staining. Immunohistochemistry was employed to assess the expression levels of thyroid transcription factor-1 （TTF-1）， neuron-specific enolase （NSE）， and proliferating cell nuclear antigen （Ki-67） in the lung tissue. High-throughput protein microarray was employed to measure the levels of interleukin-1β （IL-1β）， interleukin-6 （IL-6）， and tumor necrosis factor-α （TNF-α） in the mouse serum. Flow cytometry was employed to evaluate the expression of macrophages， myeloid-derived suppressor cells （MDSCs）， and exhausted T lymphocytes in the lung and spleen tissue. Molecular docking was performed to predict the binding affinity of 23-HBA to Janus kinase 2 （JAK2）， Src homology 2 domain-containing phosphatase 2 （SHP2）， and suppressor of cytokine signaling 3 （SOCS3）. Western blot was performed to assess the protein levels of phosphorylated-signal transducer and activator of transcription 3 （p-STAT3）， p53， and SHP2 in the M1-activated macrophages and A549 lung adenocarcinoma cells treated with 23-HBA. ResultsCompared with the normal group， the lung and spleen indexes of the model group were increased to varying degrees （P<0.05， P<0.01）， the expression of TTF-1， NSE and Ki-67 protein was significantly increased （P<0.05， P<0.01）， and the serum levels of TNF-α， IL-1β and IL-6 were significantly increased （P<0.01）. The number of macrophages in the model group was significantly decreased （P<0.01）， and the number of exhausted T cells and MDSCs was significantly increased （P<0.05， P<0.01）. Compared with the model group， the spleen and thymus index of mice in each dose group of 23-HBA decreased significantly （P<0.05）， and the lung index of mice in the middle dose group of 23-HBA decreased significantly （P<0.05）. The high and middle dose groups of 23-HBA could improve the occurrence of inflammatory infiltration and malignant lesions in the lungs of mice induced by NNK combined with LPS in the model group. The expression of TTF-1 in the middle and high dose groups of 23-HBA was significantly lower than that in the model group （P<0.05， P<0.01）. The expression of NSE and Ki-67 protein in each dose group of 23-HBA was significantly lower than that in the model group （P<0.05， P<0.01）. The contents of IL-1β in the low and high dose groups of 23-HBA were significantly decreased （P<0.05）， and the contents of IL-6 and TNF-α in each dose of 23-HBA were significantly decreased （P<0.05， P<0.01）. The number of macrophages in the lung of the middle dose group of 23-HBA was significantly increased （P<0.05）， and the number of exhausted T cells and MDSCs expressing PD-1 in the lung was significantly decreased （P<0.05， P<0.01）. In addition， 23-HBA had strong molecular docking ability to SHP2， SOCS3 and JAK2 （≥7 kcal·mol^-1）， and significantly down-regulated the protein levels of p-STAT3， SHP2 and p53 in M1 macrophages and A549 lung adenocarcinoma （P<0.01）. Conclusion23-HBA holds promise as a potential therapeutic agent for mitigating pulmonary inflammation and inhibiting malignant transformation induced by the combination of LPS and NNK. It may exert effects by regulating immune cell responses， improving the tumor immune microenvironment， and regulating key signaling pathways.