Corticosteroids and cellulose purification improve, respectively, the in vivo translation and vaccination efficacy of sa-mRNAs

• Published in: Molecular therapy 2021-04, Vol.29 (4), p.1370-1381
• Main Authors: Zhong, Zifu, McCafferty, Séan, Opsomer, Lisa, Wang, Haixiu, Huysmans, Hanne, De Temmerman, Joyca, Lienenklaus, Stefan, Portela Catani, João Paulo, Combes, Francis, Sanders, Niek N.
• Format: Article
• Language: English
• Subjects: Adrenal Cortex Hormones - chemistry; cellulose; Cellulose - chemistry; clobetasol; Clobetasol - pharmacology; Gene Expression Regulation - genetics; Humans; Immunity, Innate - drug effects; Immunity, Innate - genetics; Immunity, Innate - immunology; innate immunity inhibitors; Interferon Type I - genetics; Interferon Type I - immunology; mRNA purification; Original; Protein Biosynthesis - drug effects; Protein Biosynthesis - immunology; RNA, Messenger - chemical synthesis; RNA, Messenger - chemistry; RNA, Messenger - genetics; RNA, Messenger - pharmacology; self-amplifying mRNA; type I IFN; Vaccination; Zika vaccine; Zika Virus - drug effects; Zika Virus - pathogenicity; Zika Virus Infection - drug therapy; Zika Virus Infection - immunology; Zika Virus Infection - virology
• ISSN: 1525-0016; 1525-0024
• DOI: 10.1016/j.ymthe.2021.01.023

Synthetic mRNAs are an appealing platform with multiple biomedical applications ranging from protein replacement therapy to vaccination. In comparison with conventional mRNA, synthetic self-amplifying mRNAs (sa-mRNAs) are gaining interest because of their higher and longer-lasting expression. However, sa-mRNAs also elicit an innate immune response, which may complicate their clinical application. Approaches to reduce the innate immunity of sa-mRNAs have not been studied in detail. Here we investigated, in vivo, the effect of several innate immune inhibitors and a novel cellulose-based mRNA purification approach on the type I interferon (IFN) response and the translation and vaccination efficacy of our formerly developed sa-mRNA vaccine against Zika virus. Among the investigated inhibitors, we found that corticosteroids and especially topical application of clobetasol at the sa-mRNA injection site was the most efficient in suppressing the type I IFN response and increasing the translation of sa-mRNA. However, clobetasol prevented formation of antibodies against sa-mRNA-encoded antigens and should therefore be avoided in a vaccination context. Residual dsRNA by-products of the in vitro transcription reaction are known inducers of immediate type I IFN responses. We additionally demonstrate a drastic reduction of these dsRNA by-products upon cellulose-based purification, reducing the innate immune response and improving sa-mRNA vaccination efficacy. [Display omitted] The innate immunity of sa-mRNAs may complicate their clinical application. In this study, Zhong et al. investigated, in vivo, the effect of several innate immune inhibitors and a novel cellulose-based mRNA purification approach on the type I interferon response and the translation and vaccination efficacy of an sa-mRNA vaccine against Zika virus.