<p>Proteins encoded by mRNA vaccines can be expressed by a diversity of transfected cell types but how cell-type-specific expression influences immunity is poorly understood. To investigate this, we incorporated synthetic microRNA target sites (miRT) into lipid nanoparticle (LNP)-delivered mRNA vaccines to silence mRNA expression specifically in professional antigen-presenting cells (pAPCs), hepatocytes or myocytes. We found that mRNA expression in pAPCs was dispensable for priming antigen-specific T cells, whereas mRNA expression in myocytes induced similar or stronger immune responses, including for SARS-CoV-2, suggesting that antigen cross-presentation or cross-dressing may be more impactful than direct mRNA expression in pAPCs. In contrast, mRNA expression in hepatocytes suppressed the antigen-specific T cell response, partly through PD1/PDL1. In mice bearing tumor-associated antigen (TAA)-expressing lymphoma cells, miRT-mediated hepatocyte-silenced TAA mRNA vaccine enhanced immune response and reduced tumor burden. Thus, non-pAPC expression shapes immunity to mRNA-encoded protein and inclusion of miRTs can boost or blunt mRNA-LNP immunogenicity.</p>

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mRNA vaccine immunity is enhanced by hepatocyte detargeting and not dependent on dendritic cell expression

  • Adam Marks,
  • Sophia Siu,
  • Filippo Bianchini,
  • Chunxi Wang,
  • Ashwitha Lakshmi,
  • Matthew Phelan,
  • Andrew Zhu,
  • Chang Moon,
  • Judit Morla-Folch,
  • Abraham J. P. Teunissen,
  • Angelo Amabile,
  • Alessia Baccarini,
  • Miriam Merad,
  • Joshua D. Brody,
  • Yizhou Dong,
  • Brian D. Brown

摘要

Proteins encoded by mRNA vaccines can be expressed by a diversity of transfected cell types but how cell-type-specific expression influences immunity is poorly understood. To investigate this, we incorporated synthetic microRNA target sites (miRT) into lipid nanoparticle (LNP)-delivered mRNA vaccines to silence mRNA expression specifically in professional antigen-presenting cells (pAPCs), hepatocytes or myocytes. We found that mRNA expression in pAPCs was dispensable for priming antigen-specific T cells, whereas mRNA expression in myocytes induced similar or stronger immune responses, including for SARS-CoV-2, suggesting that antigen cross-presentation or cross-dressing may be more impactful than direct mRNA expression in pAPCs. In contrast, mRNA expression in hepatocytes suppressed the antigen-specific T cell response, partly through PD1/PDL1. In mice bearing tumor-associated antigen (TAA)-expressing lymphoma cells, miRT-mediated hepatocyte-silenced TAA mRNA vaccine enhanced immune response and reduced tumor burden. Thus, non-pAPC expression shapes immunity to mRNA-encoded protein and inclusion of miRTs can boost or blunt mRNA-LNP immunogenicity.