Murine Macrophages Modulate Their Inflammatory Profile in Response to Gas Plasma-Inactivated Pancreatic Cancer Cells

SIMPLE SUMMARY: Pancreatic cancer is a devastating disease with high mortality. The cancer is characterized by a dynamic and immunosuppressive tumor microenvironment (TME) with high numbers of macrophages. Gas plasma technology was previously suggested as a promising new tool in oncology and pancreatic cancer treatment. However, it is unclear how gas plasma-treated pancreatic cancer cells affect the phenotype and inflammatory profile of macrophages. Besides profound antitumor effects of gas plasma-exposed tumor cells, we identified in such co-cultures unique signatures of both pro- and anti-inflammatory mediators being secreted at elevated levels. These responses might be beneficial as they promote neither overshooting inflammation and metastasis nor immunosuppression, fueling tumor growth as a known consequence of anti-inflammation. ABSTRACT: Macrophages and immuno-modulation play a dominant role in the pathology of pancreatic cancer. Gas plasma is a technology recently suggested to demonstrate anticancer efficacy. To this end, two murine cell lines were employed to analyze the inflammatory consequences of plasma-treated pancreatic cancer cells (PDA) on macrophages using the kINPen plasma jet. Plasma treatment decreased the metabolic activity, viability, and migratory activity in an ROS- and treatment time-dependent manner in PDA cells in vitro. These results were confirmed in pancreatic tumors grown on chicken embryos in the TUM-CAM model (in ovo). PDA cells promote tumor-supporting M2 macrophage polarization and cluster formation. Plasma treatment of PDA cells abrogated this cluster formation with a mixed M1/M2 phenotype observed in such co-cultured macrophages. Multiplex chemokine and cytokine quantification showed a marked decrease of the neutrophil chemoattractant CXCL1, IL6, and the tumor growth supporting TGFβ and VEGF in plasma-treated compared to untreated co-culture settings. At the same time, macrophage-attractant CCL4 and MCP1 release were profoundly enhanced. These cellular and secretome data suggest that the plasma-inactivated PDA6606 cells modulate the inflammatory profile of murine RAW 264.7 macrophages favorably, which may support plasma cancer therapy.