Tumor-Derived Microvesicles Enhance Cross-Processing Ability of Clinical Grade Dendritic Cells.

Marco Dionisi,Christian Albano,Aurelia Rughetti,Federico Battisti,Chiara Napoletano,Marianna Nuti,Francesca Belleudi,Ilaria Grazia Zizzari,Claudia De Archangelis,Alessandra Di Filippo,Hassan Rahimi Koshkaki,Pierluigi Benedetti Panici,Ilary Ruscito,Maria Rosaria Torrisi

doi:10.3389/fimmu.2018.02481

Abstract

Tumor cells release extracellular microvesicles (MVs) in the microenvironment to deliver biological signals to neighboring cells as well as to cells in distant tissues. Tumor-derived MVs appear to play contradictory role promoting both immunosuppression and tumor growth and both evoking tumor specific immune response. Recent evidences indicate that tumor-derived MVs can positively impact Dendritic Cells (DCs) immunogenicity by reprogramming DC antigen processing machinery and intracellular signaling pathways, thus promoting anti-tumor response. DCs are considered pivot cells of the immune system due to their exclusive ability to coordinate the innate and acquired immune responses, cross-present exogenous antigens, and prime naïve T cells. DCs are required for the induction and maintenance of long-lasting anti-tumor immunity and their exploitation has been extensively investigated for the design of anti-tumor vaccines. However, the clinical grade culture conditions that are required to generate DCs for therapeutic use can strongly affect their functions. Here, we investigated the immunomodulatory impact of MVs carrying the MUC1 tumor glycoantigen (MVsMUC1) as immunogen formulation on clinical grade DCs grown in X-VIVO 15 (X-DCs). Results indicated that X-DCs displayed reduced performance of the antigen processing machinery in term of diminished phagocytosis and acidification of the phagosomal compartment suggesting an altered immunogenicity of clinical grade DCs. Pulsing DCs with MVsMUC1 restored phagosomal alkalinization, triggering ROS increase. This was not observed when a soluble MUC1 protein was employed (rMUC1). Concurrently, MVsMUC1 internalization by X-DCs allowed MUC1 cross-processing. Most importantly, MVsMUC1 pulsed DCs activated IFNγ response mediated by MUC1 specific CD8+ T cells. These results strongly support the employment of tumor-derived MVs as immunogen platforms for the implementation of DC-based vaccines.

Highlights

Dendritic Cells (DCs) are antigen presenting cells (APCs) crucial for the promotion and maintenance of the anti-tumor immune response due to their ability to coordinate innate and adaptive immune response and to activate T cells inducing immune memory [1, 2]
Results indicated that only MVs carrying the MUC1 tumor glycoantigen (MVsMUC1) up-take restored the phagosomal alkalinization of X-DCs and this event was dependent by the modulation of the phagosomal radical oxigen species
MUC1 cross-processing to HLA class I compartment was still occurring in X-DCs upon MV pulsing and IFNγ response mediated by MUC1 specific CD8+T cells could be triggered by MVsMUC1 pulsed DCs

Summary

Introduction

Dendritic Cells (DCs) are antigen presenting cells (APCs) crucial for the promotion and maintenance of the anti-tumor immune response due to their ability to coordinate innate and adaptive immune response and to activate T cells inducing immune memory [1, 2]. DCs are equipped with a variety of receptors able to sense tissue and cellular damage; they are endowed with an unique and powerful antigen processing machinery that enable them to crossprocess and present antigens; lastly, they display a complex pattern of costimulatory/inhibitory receptors/ligands that regulate interactions with effector immune cells [3]. These biological features empower DCs to perform T cell cross priming activating both CD4+ and CD8+ T cells [4, 5]. Optimization of immunogen formulation is crucial to compensate those biological changes that characterized DCs grown in clinical grade culture conditions and that could affect the overall immunostimulatory ability of DCs [10, 11]

Methods

Results

Conclusion