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Updated: May 14, 2026
An In vitro Model to Study Immune Responses of Human Peripheral Blood Mononuclear Cells to Human Respiratory Syncytial Virus Infection
Published on: December 10, 2013
Innate immune response and programmed cell death following carrier-mediated delivery of unmodified mRNA to
Oliwia Andries1, Marina De Filette, Stefaan C De Smedt
1Laboratory of Gene Therapy, Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Heidestraat 19, B-9820 Merelbeke, Belgium.
Abstract:
In this report we show that carrier-mediated delivery of mRNA may activate TLR3 signaling in respiratory cells. This activation of the innate immune system was accompanied with a massive production of type 1 interferons and other immunostimulating cytokines. The recognition of mRNA by the innate immune system was also associated with cell death, which proceeded in human respiratory cells via pyroptosis, a form of programmed cell death mediated by substantial overexpression of caspase-1. This indicated that the delivered mRNA is most likely also recognized by NOD-like receptors which regulate caspase-1 production. The viability of murine respiratory cells was less affected by mRNA transfection, which is in line with the lower transfection efficiency, lower innate immune response and the absence of a massive caspase-1 upregulation in these cells. Finally, we also demonstrated that the recognition of the delivered mRNA by the innate immune system had a negative effect on mRNA translation.
Insights
Messenger RNA (mRNA) delivery activates innate immunity in respiratory cells via TLR3 and NOD-like receptors, causing cell death and reduced translation. Murine cells showed a milder response due to lower transfection efficiency.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Carrier-mediated delivery of mRNA is a key technology in modern therapeutics.
- The innate immune system's recognition of foreign nucleic acids can trigger inflammatory responses.
- Understanding these interactions is crucial for optimizing mRNA-based therapies.
Purpose of the Study:
- To investigate the activation of innate immune signaling pathways by carrier-mediated mRNA delivery in respiratory cells.
- To characterize the cellular response, including cell death mechanisms and cytokine production.
- To compare the responses in human versus murine respiratory cells.
Main Methods:
- mRNA transfection into human and murine respiratory cell lines.
- Analysis of Toll-like receptor 3 (TLR3) and NOD-like receptor (NLR) signaling.
- Measurement of type 1 interferons and cytokine production.
- Assessment of cell viability and identification of cell death pathways (e.g., pyroptosis via caspase-1).
- Evaluation of mRNA translation efficiency.
Main Results:
- mRNA delivery activated TLR3 signaling and induced massive production of type 1 interferons and immunostimulating cytokines in human respiratory cells.
- Cell death via pyroptosis, mediated by caspase-1 overexpression, was observed in human cells, suggesting recognition by NLRs.
- Murine respiratory cells exhibited a less pronounced response, correlating with lower transfection efficiency and minimal caspase-1 upregulation.
- Innate immune recognition of delivered mRNA negatively impacted mRNA translation.
Conclusions:
- Carrier-mediated mRNA delivery can activate innate immune responses in respiratory cells, particularly via TLR3 and NLR pathways.
- Human respiratory cells are more susceptible to mRNA-induced pyroptosis and immune activation compared to murine cells.
- The innate immune response to delivered mRNA can hinder its translational efficiency, posing a challenge for mRNA-based therapies.
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