Abstract
Background: Mycosis fungoides (MF) is the most common cutaneous T cell lymphoma (CTCL). Tumor-derived exosomes are endosome-derived extra-cellular-vesicles secreted by cancer cells to create tumor favorable niche. We previously demonstrated that MF-exosomes deliver a significant load of miR-155 and miR-1246 into recipient cells and increase their motility. Literature MF-derived exosomes is strikingly lacking.
Objective: We aim to characterize the protein profile of MF-derived exosomes and to explore the effect of MF-exosomes on immune cells and tumor heterogeneity.
Material and methods: MF-exosomes were isolated from CTCL cell lines and plasma samples from patients with early-MF and healthy controls, using ultracentrifugation. Exosome proteomic content was analyzed via mass spectrometry, verified by FACS-beads, and exosome-protein delivery by immunostaining of target cells. Survival by MTT viability assay. Apoptosis via FACS of annexin-V+PI staining. Treg cells were identified through FACS and FOXP3 expression by qRT-PCR. Immune cell characterization and expression of immune regulators were assessed using mass flow cytometry by time of flight (CyTOF).
Results: OX40, GITR, CXCR4, CD44, and CD30 were identified in MF exosomes. MJ-Exosomes (advanced-MF) desensitized MyLa-cells (localized-MF) to doxorubicin in dependency on CXCR4 receptor. MF-exosomes facilitated apoptosis of T-cells and Treg expansion. CyTOF of PBMCs from healthy donors showed that MF-exosomes decrease the frequency of Th1, TEM/CD4+, Th17, Teffectory/CD8+, M1, and DC, whereas the frequency of M2 increased the expression of PD-L1and CTLA-4.
Conclusions: Our study characterized the protein cargo of MF-exosomes and offers a novel exosome-mediated mechanism underlying immune evasion and chemoresistance in MF.
Keywords
Exosomes, Mycosis fungoides (MF), Cutaneous T cell lymphoma (CTCL), PD-L1, Immune evasion