Ceria Nanoparticles Promoted The Cytotoxic Activity Of CD8~+ T Cells

Background Cytotoxic CD8~+T cells(CTLs)are crucial for controlling cancer and intracellular pathogens including viruses and intracellular bacteria.Upon encountering their cognate antigen,the antigen-specific na?ve CD8~+T cells are activated by antigen presenting cells in secondary lymphoid organs.The activated CD8~+T cells are subjected to clonal expansion and generating massive cytolytic effector cells.The effector cells then migrate to all corners of the body to clear the infected cells and pathogens.During the infected cells and pathogens clearance,CTL cells produce multiple cytokines and release cytolytic effector molecules.Nowadays,Cancer and chronic infection threaten peoples’health.Although anti-cancer therapies such as ACT therapies have made remarkable progress,especially CAR T cell therapy,which has gained commercial approval by the U.S.FDA,severe cytokine release syndrome(CRS)and neurotoxicity have been observed.It is an urgent requirement to find out an efficient method to promote the cytotoxicity activity of CTL cells,especially in vitro.Ceria nanoparticles(CNPs),which have analogous activity of two key antioxidant enzymes,superoxide dismutase and catalase,possess fascinating pharmacological potential owing to scavenging intracellular reactive oxygen species(ROS)and preventing the ROS accumulation.In fact,based on these excellent antioxidant activities,CNPs have been used as a therapeutic for various chronic diseases associated with oxidative stress,such as cancer,inflammation,azhi diabetes,obesity,cardiovascular diseases,retinal damage,and neurodegeneration.But the role of CNPs in CTL cells is still unclear.It is recently reported that through the regulation of NF-κB signaling,low/moderate levels of ROS are positive contributors to immune responses.In consideration of the importance of NF-κB signaling in the function of CTL cells and the correlation between ROS and NF-κB signaling,in this study,we used the homemade CNPs explored the function and mechanisms that CNPs made to CTL cells.Methods 1.The enriched na?ve CD8~+T cells from P14 transgenic mice and C57BL/6J mice were activated in vitro and simultaneously treated with different concentrations of CNPs(0,10μM,100μM,500μM,and 1000μM).The survival of CTL cells were detected by Annexin V and 7-AAD detection.The proliferation of CTL cells were detected by carboxyfluorescein diacetate succinimidyl ester(CFSE)labeling and Ki-67 detection.2.The enriched na?ve CD8~+T cells from P14 transgenic mice and C57BL/6J mice were activated in vitro and simultaneously treated with different concentrations of CNPs(0,10μM,100μM).The cytokine production and effector molecule release of CTL cells were detected by intracellular staining for IFN-γ,TNF-α,IL-2,granzyme B,perforin.3.The in vitro and in vivo killing ability of CTL cells after CNPs treatment was tested by in vitro killing assay and virus titers detection.4.DCFDA Cellular ROS Detection Assay Kit and Mitochondria Staining Kit were used to detect ROS production and mitochondrial membrane potential.Immunoblot Analysis was used to detectβ-actin,IκBα,Phospho-IκBα,IKKβexpression.5.IKKβinhibitor IMD-0354 was used to block IκBαphosphorylation in NF-κB signaling to explore the mechanisms.Results 1.After CNPs treatment,there is no differences among all the groups.It means that CNPs have no effect on the survival and proliferation of CTL cells.2.Our results demonstrate that CNPs treatment promotes cytokine production and effector molecule release of CTL cells,suggesting that CNPs treatment may enhance the antigen-specific killing ability of CTL cells.3.Our findings demonstrate that CNPs treatment promotes the antigen-specific killing activity of CTL cells both in vitro and in vivo.4.Our findings demonstrate that CNPs treatment decreases ROS production via downregulation of MMP in CTL cells and then activates NF-κB signaling.5.Our findings demonstrate that inhibition of NF-κB signaling lowers the killing activity of cytotoxic CD8~+T cells via reductions of cytokine production and effector molecule release.Conclusion In conclusion,the CTL cells by CNPs treatment reduced the MMP and then decreased ROS production.The lowered ROS activated NF-κB signaling,and therefore promoted the production of cytokines and release of cytolytic effector molecules,and eventually enhanced the antigen-specific killing activity against cancer cells and infected cells by viruses and intracellular bacteria.Our findings provide new ideas in usage of CNPs for clinical application such as cancer immunotherapy,although its role in ACT therapy needs to be further investigated.