AC decoction augments chemotherapy in NSCLC by reshaping the tumor immune microenvironment: attenuating Tregs and enhancing CD8 T cells.

The Astragalus membranaceus - Codonopsis pilosula decoction (ACD), is traditionally used as beverage to activate immunity. This study aimed to investigate the combined use of ACD and TP (paclitaxel and cisplatin) against non-small cell lung cancer (NSCLC) in a orthotopic mouse model. In this study, the anti-tumor and immunomodulation efficacies of ACD and TP were evaluated in an orthotopic lung cancer model. After treatment with ACD for one week, the luciferase-expressing Lewis cells were injected into the lungs of male C57 mice and treated with ACD and/or TP for about 2 weeks. Then, the flow cytometry, ELISA, IHC and WB were employed to assess immune cell populations, cytokine production and protein expression levels. Besides, in vitro cytotoxicity of ACD against NSCLC cells was performed using CCK-8 assays, while its immunomodulatory potential was evaluated using a co-culture system incorporating NSCLC cells and patient-derived PBMCs. Our results demonstrated that combination of ACD and TP had the most potent effects on tumor burden and immunity activation among treatment groups. ACD (1 g/kg) and TP (paclitaxel 22.5 mg/kg, cisplatin 12.5 mg/kg) treatment reduced tumor burden by 53.16%, as validated by IVIS imaging in the mouse model. Flow cytometry from mice spleens proved that the combined use of ACD and TP treatment significantly decreased Treg production and increased CD4 and CD8 T cell infiltration. Besides, ACD and TP treatment resulted in downregulation of FOXP3 and EZH2 expression, and suppression of PI3K/AKT phosphorylation in mice tumor. Furthermore, in vivo results showed that ACD had no direct cytotoxicity against NSCLC cells, which significantly enhanced PBMC-mediated tumor cell killing and promoted IFN-γ and TNF-α production in patient-derived co-culture systems. In conclusion, the combination of ACD plus TP demonstrated potent anti-tumor and immunomodulation effects against NSCLC in association with reduced Treg activity and increased CD8 T cell infiltration. Our study provides compelling preclinical evidence supporting ACD as an immunomodulatory adjunct to conventional NSCLC therapies.