Membrane-bound HSP70-engineered myeloma cell-derived exosomes stimulate more efficient CD8(+) CTL- and NK-mediated antitumour immunity than exosomes released from heat-shocked tumour cells expressing cytoplasmic HSP70.
Bottom Line: We found that EXO(HSP) were able to more efficiently stimulate maturation of DCs with up-regulation of Ia(b) , CD40, CD80 and inflammatory cytokines than EXO(HS) after overnight incubation of immature bone-marrow-derived DCs (5 × 10⁶ cells) with EXO (100 μg), respectively.In addition, we further elucidate that EXO(HSP) -stimulated antitumour immunity is mediated by both P1A-specific CD8(+) CTL and non-P1A-specific natural killer (NK) responses.Therefore, membrane-bound HSP70-expressing tumour cell-released EXO may represent a more effective EXO-based vaccine in induction of antitumour immunity.
Affiliation: Research Unit, Division of Health Research, Saskatchewan Cancer Agency, Department of Oncology, University of Saskatchewan, Saskatoon, Canada.Show MeSH
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Mentions: It has been demonstrated that HSP70 can stimulate DC maturation . To assess whether EXOHSP were also able to stimulate DC maturation, we analysed immature DCs cultured with EXOHSP expressing membrane-bound HSP70 or EXOHS expressing cytoplasmic HSP70 or EXOneo without HSP70 expression. EXOneo-stimulated DCs still showed a similar pattern of the expression of the above molecules on immature DCs (Fig. 3A), indicating that EXOneo does not modulate DC maturation. Interestingly, we found that EXOHS- and EXOHSP-stimulated DCs up-regulated expression of Iad, CD40 and CD80, indicating that both EXOHS and EXOHSP are able to stimulate DC maturation. However, the up-regulation of the above molecules stimulated by the later was more than the former, indicating that EXOHSP is a stronger stimulator for DC maturation than EXOHS. In addition, EXOHSP-stimulated mature DCs also secreted more amount of inflammatory cytokines such as IL-1β (1.8 ng/ml/106 cells/24 hrs), IL-12 (1.1 ng/ml/106 cells/24 hrs), IFN-γ (0.8 ng/ml/106 cells/24 hrs) and tumour necrosis factor (TNF)-α (0.9 ng/ml/106 cells/24 hrs) (Fig. 3B) than EXOHS-stimulated DCs. Since EXOHSP harboured the above immune molecules, they may have potent effect in stimulation of T-cell immune responses . We first assessed whether DCs with uptake of EXO by incubation of immature DCs with EXO for overnight stimulate allogeneic T-cell proliferation in a mixed T lymphocyte reaction assay. As shown in Fig. 3C, DCs with uptake of EXOHSP (DC + EXOHSP) stimulated the strongest allogeneic T-cell proliferation than DCs with uptake of EXOneo (DC + EXOneo) and EXOHS (DC + EXOHS) (P < 0.05). We then assessed whether DCs with uptake of EXO by incubation of immature DCs with EXO for overnight induce P1A-specific antitumour immunity. As shown in Fig. 3(D), DCs with uptake of EXOneo (DC + EXOneo), EXOHS (DC + EXOHS) and EXOHSP (DC + EXOHSP) were able to stimulate P1A-specific antitumour immunity to protect one of eight, three of eight and eight of eight mice from tumour growth after the immunized mice were challenged with J558 tumour cells, respectively, indicating that EXOHSP-treated DCs are the most immunogenic among these three types of DCs.
Affiliation: Research Unit, Division of Health Research, Saskatchewan Cancer Agency, Department of Oncology, University of Saskatchewan, Saskatoon, Canada.