Effects of imiquimod on macrophages by transcriptomic analysis

Imiquimod is a small-molecule immunomodulator with anti-tumor effects, and its anti-tumor activity mainly relies on its immunomodulatory capacity, including activating dendritic cells， T cells, natural killer cells, and promoting the migration of antigen-presenting cells. In this study, we pretreated mouse bone marrow-derived macrophages (BMDMs) with imiquimod for 24 hours and conducted transcriptomic analysis to explore the mechanism by which imiquimod regulates macrophages to exert anti-tumor effects. We found that imiquimod pretreatment of macrophages upregulated multiple signaling pathways, with the most significant being immune regulation-related signaling pathways. Notably, pathways such as the NF-κB pathway, Toll-like receptor (TLR) pathway were significantly upregulated. We infer that imiquimod activates TLR pathway and the downstream NF-κB pathway, promoting the polarization of macrophages to a pro-inflammatory phenotype and exerting anti-tumor effects. Mouse macrophages were extracted from bone marrow and pretreated with dimethylsulfoxide (DMSO, as negative control), imiquimod, and lipopolysaccharides (LPS, as positive control) in three replicate, respectively. After 24h pretreatment, each group of cells is collected and proceeds for RNA sequencing.