Type I IFN Counteracts the Induction of Antigen-Specific Immune Responses by Lipid-Based Delivery of mRNA Vaccines

Abstract

The use of DNA and viral vector-based vaccines for the induction of cellular immune responses is increasingly gaining interest. However, concerns have been raised regarding the safety of these immunization strategies. Due to the lack of their genome integration, mRNA-based vaccines have emerged as a promising alternative. In this study, we evaluated the potency of antigen-encoding mRNA complexed with the cationic lipid 1,2-dioleoyl-3trimethylammonium-propane/1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOTAP/DOPE ) as a novel vaccination approach. We demonstrate that subcutaneous immunization of mice with mRNA encoding the HIV-1 antigen Gag complexed with DOTAP/DOPE elicits antigen-specific, functional T cell responses resulting in specific killing of Gag peptide-pulsed cells and the induction of humoral responses. In addition, we show that DOTAP/DOPE complexed antigen-encoding mRNA displays immune-activating properties characterized by secretion of type I interferon (IFN) and the recruitment of proinflammatory monocytes to the draining lymph nodes. Finally, we demonstrate that type I IFN inhibit the expression of DOTAP/DOPE complexed antigen-encoding mRNA and the subsequent induction of antigen-specific immune responses. These results are of high relevance as they will stimulate the design and development of improved mRNA-based vaccination approaches.

Dendrimer-RNA nanoparticles generate protective immunity against lethal Ebola, H1N1 influenza, and Toxoplasma gondii challenges with a single dose

“…Furthermore, cationic lipids can be immunogenic, which can limit transgene expression and raise safety concerns (88). IFN production in response to lipid-complexed mRNA can limit efficacy of mRNAbased vaccines (34). Various nanoparticle formats have demonstrated varying levels of efficacy through intradermal (89), intrasplenic (90), subcutaneous (34), intravenous (89,91), and even intranasal (92) routes of administration.…”

“…However, delivery is required for replicon mRNA function, and, to date, there has been no report of protective immunity capable of allowing for survival against a lethal challenge of any pathogen using nonviral, fully synthetic approaches (32). Naked replicon mRNA can activate the innate immune system upon administration, which can limit translational efficiency, diminish potency, and induce toxicity (33)(34)(35)(36). RNA, particularly single-stranded RNA, is rapidly degraded by nucleases when injected in vivo (37).…”

Induction of an IFN-Mediated Antiviral Response by a Self-Amplifying RNA Vaccine: Implications for Vaccine Design

“…The observed increase in Ag expression in mice with abrogated type I IFN signaling may be the result of increased translational efficiency of SAM-encoded Ag. Indeed, it has been reported that type I IFN impairs exogenous mRNA translation (39,40). In addition, as reported by Cruz et al (41), specific single mutations in nsP1 sequence of alphaviruses increase type I IFN levels in vitro as well as in vivo and determine the virus virulence attenuation.…”

Induction of Broad-Based Immunity and Protective Efficacy by Self-amplifying mRNA Vaccines Encoding Influenza Virus Hemagglutinin

“…Furthermore, in the process of amplification of their genomes, RNA replicons engage pattern recognition receptors in the host cell, adjuvanting the responses to the encoded immunogen (45)(46)(47). Although both mRNA-and replicon RNA-based vaccines were shown to elicit antigen-specific antibody and cellular immune responses against several pathogens (44,(48)(49)(50)(51), the self-amplifying nature of replicon-based vaccines is likely to result in higher levels of antigen expression and in a more effective engagement of innate immune responses than mRNA-based vaccine candidates.…”