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    Activation of murine immune cells upon co-culture with plasma-treated B16F10 melanoma cells
    (Basel : MDPI, 2019) Rödder, Katrin; Moritz, Juliane; Miller, Vandana; Weltmann, Klaus-Dieter; Metelmann, Hans-Robert; Gandhirajan, Rajesh; Bekeschus, Sander
    Recent advances in melanoma therapy increased median survival in patients. However, death rates are still high, motivating the need of novel avenues in melanoma treatment. Cold physical plasma expels a cocktail of reactive species that have been suggested for cancer treatment. High species concentrations can be used to exploit apoptotic redox signaling pathways in tumor cells. Moreover, an immune-stimulatory role of plasma treatment, as well as plasma-killed tumor cells, was recently proposed, but studies using primary immune cells are scarce. To this end, we investigated the role of plasma-treated murine B16F10 melanoma cells in modulating murine immune cells' activation and marker profile. Melanoma cells exposed to plasma showed reduced metabolic and migratory activity, and an increased release of danger signals (ATP, CXCL1). This led to an altered cytokine profile with interleukin-1β (IL-1β) and CCL4 being significantly increased in plasma-treated mono- and co-cultures with immune cells. In T cells, plasma-treated melanoma cells induced extracellular signal-regulated Kinase (ERK) phosphorylation and increased CD28 expression, suggesting their activation. In monocytes, CD115 expression was elevated as a marker for activation. In summary, here we provide proof of concept that plasma-killed tumor cells are recognized immunologically, and that plasma exerts stimulating effects on immune cells alone. © 2019 by the authors.
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    Potentiating anti-tumor immunity with physical plasma
    (Amsterdam [u.a.] : Elsevier, 2018) Bekeschus, Sander; Clemen, Ramona; Metelmann, Hans-Robert
    The age of checkpoint blockage emphasizes the importance of adaptive antitumor immune responses. This arm of immune defense is key in recognizing molecules via specific receptors to distinguish between self and foreign or mutated structures. Antigen-specific T-cells identify non-self epitopes, tumor-associated antigens, or neoepitopes on tumors to carry out attacks on malignant cells. Although tumor cells are immunogenic by nature, they have developed strategies to evade an immune response that would otherwise facilitate their clearance. Several steps in antitumor immunity utilize the toxic and signaling properties of reactive oxygen and nitrogen species (ROS/RNS). Cold physical plasmas are potent generators of such ROS/RNS and are demonstrated to have profound antitumor activity in vitro and in vivo. Here we discuss recent evidence and concepts on how plasmas may boost immunity against pathological cells. Specifically, plasma treatment may enhance the immunogenicity of tumor cells by induction of the immunogenic cancer cell death (ICD) and redox regulation of the antigen-presenting machinery. These aspects provide a rationale for localized plasma-based onco-therapies enhancing systemic antitumor immunity, which eventually may target distant tumor metastasis in cancer patients in a T-cell dependent fashion.