Screening of Human M2 Macrophage-Specific Markers for Preparation of Humanized Inflammation-Triggering Engineered...

We previously reported the development of inflammation-triggering engineered mouse macrophages (mMacTriggers) that achieve tumor-specific release of tumor necrosis factor-α (TNF-α) in response to the promoter of Arginase 1 (Arg1), an M2-specific marker in murine macrophages. Tumor-specific TNF-α release induced acute inflammation, which recruited natural killer cells or cytotoxic T cells to attack the tumor, leading to significant antitumor effects. This strategy primarily leverages innate immunity-mediated tumor suppression, which is expected to have minimal side effects-an approach noted worldwide. However, we have one issue with preparing human macrophage-derived MacTrigger (hMacTrigger) for clinical application: the Arg1 promoter is unsuitable for human use due to the low expression of Arg1 in human macrophages. Therefore, this study aimed to identify human M2 macrophage-specific markers to replace murine Arg1 through data analysis and quantitative evaluation. From an initial selection of 30 gene candidates by data analysis, we identified 8 genes with high specificity by quantitative evaluation. Among them, 4 genes-arachidonate 15-lipoxygenase (ALOX15), sialic acid-binding immunoglobulin (Ig)-like lectin 10 (SIGLEC10), fatty acid binding protein 4 (FABP4), and C-C motif chemokine ligand 22 (CCL22)-were confirmed as M2-specific markers in human macrophages. Future research will focus on preparing hMacTrigger by constructing vectors encoding TNF-α under the control of each identified gene promoter and evaluating its anti-tumor effects and side effects in vivo. This study represents a critical step toward the clinical application of the MacTrigger strategy and advances its potential use in cancer immunotherapy.