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Studying the Effects of Tumor-Secreted Paracrine Ligands on Macrophage Activation using Co-Culture with Permeable Membrane Supports
Published on: November 28, 2019
Atmospheric pressure plasma-activated medium activates macrophages toward an antitumor M1 phenotype by modulating the
Jinren Liu1, Yifei Jiang2, Linghui Zhong2
1Key Laboratory for Disease Prevention and Control and Health Promotion of Shaanxi Province, School of Public Health, Medical Science Center, Xi'an Jiaotong University, Xi'an, China; Xi'an Key Laboratory of Toxicology and Biological Effect, Institute for Hygiene of Ordnance Industry, Xi'an, China.
Abstract:
Macrophage-mediated tumor clearance is frequently restricted by the immunosuppressive tumor microenvironment. This study investigates the immunomodulatory effects of plasma-activated medium (PAM) on macrophage pro-inflammatory activation and antitumor function. Murine RAW264.7 and primary bone marrow-derived macrophages were treated with PAM generated by a helium atmospheric pressure plasma jet. Phenotypic changes and underlying signaling mechanisms were assessed. Functional enhancements in macrophage recruitment and tumor engulfment were quantified using chemotaxis and 3D confocal co-culture assays with Panc02 pancreatic cancer cells. Results show that PAM promotes macrophage activation by increasing spatial recruitment via pro-inflammatory chemokine secretion and enhancing tumor cell engulfment. Mechanistically, PAM drives this functional shift through hierarchical activation of the TLR4/NF-κB and PI3K/AKT signaling cascades. Furthermore, while hydrogen peroxide alone triggers a compensatory upregulation of the inhibitory SIRPα receptor, the reactive oxygen and nitrogen species (RONS) in PAM bypass this negative feedback to directly downregulate SIRPα. These findings demonstrate that PAM-mediated oxidative modulation effectively suppresses the "don't-eat-me" signal and enhances innate antitumor immunity, providing a potential strategy for cancer immunotherapy.
Insights
Plasma-activated medium (PAM) enhances macrophage antitumor activity by promoting recruitment and engulfment of cancer cells. PAM overcomes immunosuppression by modulating key signaling pathways and downregulating inhibitory receptors.
Area of Science:
- Immunology
- Cancer Biology
- Biomedical Engineering
Background:
- The tumor microenvironment often suppresses macrophage-mediated cancer cell clearance.
- Developing strategies to enhance macrophage antitumor functions is crucial for effective cancer immunotherapy.
Purpose of the Study:
- To investigate the immunomodulatory effects of plasma-activated medium (PAM) on macrophage activation and antitumor capabilities.
- To elucidate the underlying signaling mechanisms responsible for PAM-induced functional enhancements in macrophages.
Main Methods:
- Treatment of murine macrophages (RAW264.7 and primary bone marrow-derived) with helium atmospheric pressure plasma jet-generated PAM.
- Assessment of phenotypic changes and signaling pathway activation (TLR4/NF-κB, PI3K/AKT).
- Quantification of macrophage recruitment and tumor cell engulfment using chemotaxis and 3D confocal co-culture assays with pancreatic cancer cells.
Main Results:
- PAM significantly enhanced macrophage spatial recruitment and tumor cell engulfment.
- PAM activated the TLR4/NF-κB and PI3K/AKT signaling cascades, driving macrophage pro-inflammatory and phagocytic functions.
- PAM's reactive oxygen and nitrogen species (RONS) bypassed negative feedback to downregulate the inhibitory SIRPα receptor, overcoming the 'don't-eat-me' signal.
Conclusions:
- PAM effectively modulates macrophages to enhance innate antitumor immunity.
- PAM represents a promising strategy for cancer immunotherapy by overcoming tumor-induced immunosuppression.
