Study on the mechanism of IL-4 protein in tumor immunosuppressive myelopoiesis

1. Myeloid Cell Alterations in Tumor Immune Evasion

During tumor formation, the immune system undergoes systemic changes. Among myeloid cells, bone marrow progenitor populations and immunosuppressive immature monocytes and neutrophils are mobilized into the bloodstream. Among lymphoid cells, the frequency of CD4-positive regulatory T cells and regulatory B cells increases systemically, and regulatory T cells undergo clonal expansion in the periphery before infiltrating tumors. Concurrently, the frequency of dendritic cells and CD8-positive, CD4-positive T cells decreases, along with a reduction in T cell receptor repertoire diversity. Mouse models also exhibit accumulation of naive neutrophils, monocytes, and dendritic cells, while dendritic cell and T cell populations decline. The accumulation of immature myeloid cells is one of the key strategies for tumor immune evasion.

2. Discovery of IL-4 Protein-Driven Tumor-Associated Myelopoiesis

A 2023 study published in Nature revealed the critical role of IL-4 protein in tumor immunosuppression. The study found that IL-4 protein is a major driver of tumor-infiltrating monocyte-derived macrophages, with bone marrow-derived IL-4 acting on granulocyte-monocyte progenitor cells to promote immunosuppressive myeloid cell generation. Preliminary research used single-cell RNA sequencing to map the immune landscape of human and mouse lung adenocarcinoma lesions, identifying a subset of mature dendritic cells rich in regulatory molecules with immunosuppressive functions. Further investigation showed that IL-4 protein is involved in regulating this cell subset, and blocking IL-4 significantly reduced lung tumor burden in mouse models of lung adenocarcinoma and melanoma metastasis.

3. Localization of IL-4 Protein Target Cells

To clarify the target cell types of IL-4 protein, researchers constructed mouse models with specific deletion of the IL-4 receptor α subunit in dendritic cells, tissue-resident dendritic cells, or T cells. Results showed no significant difference in tumor burden among these mice, suggesting another immune cell type responds to IL-4 to promote tumor progression. Enrichment analysis of differential genes in lung cancer-infiltrating monocyte-macrophages and tissue-resident monocytes revealed the IL-4 signaling pathway was most enriched in human and mouse monocyte-derived macrophages.

4. Critical Role of IL-4 Receptor in Bone Marrow Granulocyte-Monocyte Progenitors

Researchers crossed IL-4 receptor α subunit conditional knockout mice with Ms4a3-cre mice, where Cre recombinase is highly expressed in bone marrow granulocyte-monocyte progenitors, inducing gene deletion in all downstream lineages while preserving tissue-resident monocytes. Compared to wild-type controls, granulocyte-monocyte progenitor-specific IL-4 receptor α subunit knockout mice exhibited an 85% reduction in tumor burden, indicating IL-4 signaling in these progenitors is key to tumor suppression. Tumor-bearing mice also showed significantly fewer monocyte-derived macrophages and circulating monocytes. Single-cell RNA sequencing captured all expected immune cell populations, with marked differences in IL-4 receptor α subunit knockout mice, suggesting the deletion enhanced immunogenicity of monocytes and monocyte-derived macrophages, reprogramming the lung tumor microenvironment to an inflammatory, anti-tumor state.

5. Stage-Specificity of IL-4 Action on Early Myeloid Progenitors

Further crosses of IL-4 receptor α subunit conditional knockout mice with Cx3cr1-cre or S100a8-cre mice—where Cre recombinase is expressed in more mature myeloid cells downstream of granulocyte-monocyte progenitors, strongly biased toward monocyte and neutrophil lineages—showed no reduction in lung tumor burden. This finding demonstrates that IL-4 receptor α subunit deletion in early myeloid progenitors drives reprogramming of the lung tumor microenvironment and tumor burden reduction, while deletion in mature monocyte-derived macrophages and neutrophils does not affect tumor progression.

6. Source of IL-4 Protein and Signaling Axis Model

Additional studies revealed that IL-4 receptor α subunit signaling regulates transcriptional expression in bone marrow progenitors of tumor-bearing mice, phenotypes reproducible by exposing bone marrow to IL-4 protein in vivo. Researchers also identified basophils as the primary source of IL-4 protein in bone marrow, not lung tumor tissue. Based on these findings, they proposed a complex signaling axis: tumor microenvironment-derived soluble factors circulate to bone marrow, acting on type 2 granulocytes (basophils), which produce IL-4 protein to regulate immunosuppressive myeloid cell differentiation and tumor progression via the IL-4 receptor α subunit.

7. Research Significance and Clinical Prospects

This study elucidates the central role of IL-4 protein in tumor immunosuppressive myelopoiesis, defining the mechanism by which bone marrow-derived IL-4 acts on granulocyte-monocyte progenitors to generate immunosuppressive myeloid cells. The discovery highlights IL-4 protein's critical function in tumor immunosuppression and its potential as a target for combined immune checkpoint blockade therapies. This mechanistic insight provides a theoretical foundation for interventions targeting the immunosuppressive tumor microenvironment. Future research will explore tumor-derived soluble factors and their molecular mechanisms of action on bone marrow basophils.

8. Which Manufacturers Supply IL-4 Protein?

Nanjing UA-Biotech Co., Ltd. (UA-Bio) has independently developed "IL-4 Protein, Mouse", a high-quality recombinant protein reagent designed for studying Th2 immune responses, B cell activation, and allergic disease models in mice. This mouse-derived interleukin-4 (IL-4) efficiently activates IL-4 receptor signaling, inducing Th2 cell differentiation, B cell class switching, and IgE production, serving as a stable, reliable tool for constructing mouse allergy models, immune regulation research, and preclinical drug evaluation.

Nanjing UA-Biotech Co., Ltd. is dedicated to delivering cutting-edge, high-quality reagents and tools for immunology, cell therapy, and drug discovery. For detailed technical specifications, validation data, or inquiries regarding "IL-4 Protein, Mouse" (Catalog #: UA040470), please contact us.