Uptake of synthetic naked RNA by skin-resident dendritic cells via macropinocytosis allows antigen expression and induction of T-cell responses in mice
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Intradermal administration of antigen-encoding RNA has entered clinical testing for cancer vaccination. However, insight into the underlying mechanism of RNA uptake, translation and antigen presentation is still limited. Utilizing pharmacologically optimized naked RNA, the dose–response kinetics revealed a rise in reporter signal with increasing RNA amounts and a prolonged RNA translation of reporter protein up to 30 days after intradermal injection. Dendritic cells (DCs) in the dermis were shown to engulf RNA, and the signal arising from the reporter RNA was significantly diminished after DC depletion. Macropinocytosis was relevant for intradermal RNA uptake and translation in vitro and in vivo. By combining intradermal RNA vaccination and inhibition of macropinocytosis, we show that effective priming of antigen-specific CD8+ T-cells also relies on this uptake mechanism. This report demonstrates that direct antigen translation by dermal DCs after intradermal naked RNA vaccination is relevant for efficient priming of antigen-specific T-cells.
KeywordsNaked RNA Intradermal vaccination Macropinocytosis Dermal dendritic cell RNA vaccine Cancer immunotherapy
Diphtheria toxin receptor
Enhanced green fluorescent protein
Standard error of mean
We thank M. Brkic for immunofluorescence staining; S. Witzel, B. Tillmann, S. Wurzel and Z. Yildiz for cloning of constructs; S. Kind, M. Mechler, F. Wille, B. Otte and S. Petri for RNA production; and T. Beissert and A. Kong for proofreading of the manuscript. The study was supported by the CI3 excellence cluster program of the Federal Ministry of Education and Research (BMBF) to U. Sahin and by German Research Foundation (DFG) Grant within TR 156, project A03 to E. von Stebut.
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Conflict of interest
Ugur Sahin is a stock owner and management board member of BioNTech AG (Mainz, Germany). Mustafa Diken and Sebastian Kreiter are working as advisors for BioNTech RNA Pharmaceuticals GmbH. All other authors have no potential conflict of interest.
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