The mRNA-LNP platform’s lipid nanoparticle component used in preclinical vaccine studies is highly inflammatory

Abstract

Vaccines based on mRNA-containing lipid nanoparticles (LNPs) are a promising new platform used by two leading vaccines against coronavirus disease in 2019 (COVID-19). Clinical trials and ongoing vaccinations present with very high protection levels with varying degrees of side effects. However, the nature of the reported side effects remains poorly defined. Here we present evidence that LNPs used in many preclinical studies are highly inflammatory in mice. Intradermal injection of these LNPs led to rapid and robust inflammatory responses, characterized by massive neutrophil infiltration, activation of diverse inflammatory pathways, and production of various inflammatory cytokines and chemokines. The same dose of LNP delivered intranasally led to similar inflammatory responses in the lung and resulted in a high mortality rate. In summary, here we show that the LNPs used for many preclinical studies are highly inflammatory. Thus, their potent adjuvant activity and reported superiority comparing to other adjuvants in supporting the induction of adaptive immune responses could stem from their inflammatory nature. Furthermore, the preclinical LNPs are similar to the ones used for human vaccines, which could also explain the observed side effects in humans using this platform.

Langerhans cells and cDC1s play redundant roles in mRNA-LNP induced protective anti-influenza and anti-SARS-CoV-2 responses

“…Therefore, here we tested the contribution of LCs and cDC1s in regulating adaptive immune responses triggered by this mRNA-LNP platform. Mice deficient in LCs (huLang-DTA, LC -/- ; (Kaplan et al, 2005)), cDC1s (Batf3 -/- , cDC1 -/- ; (Edelson et al, 2010)), or both (huLang-DTA by Batf3 -/- , DKO; (Welty et al, 2013)), and littermate WT controls were intradermally immunized with 10 μg of mRNA-LNP coding for PR8 HA (Pardi et al, 2018a) as we previously described (Ndeupen et al, 2021). Seven and fourteen days later the Tfh and B cell responses were analyzed using flow cytometry in the skin draining lymph nodes.…”

“…The mRNA-LNP platform through its ionizable lipid component triggers robust, rapid, but transient neutrophil infiltration at the delivery site (Ndeupen et al, 2021). Through induction of inflammatory milieu and activation of local APCs, and other cellular and molecular interactions, neutrophils can contribute to the generation of downstream adaptive immune responses (Van Gisbergen et al, 2005; Leliefeld et al, 2015; Li et al, 2019; Ludwig et al, 2006; Schuster et al, 2012).…”

“…We recently described that the mRNA-LNP platform built on the nucleoside modified mRNA pioneered at the University of Pennsylvania by Karikó and Weissman (Karikó et al, 2005, 2011) combined with the proprietary LNPs of Acuitas Therapeutics is highly inflammatory (Ndeupen et al, 2021). The inflammatory property of this platform was likely due to its ionizable lipid component that led to activation of multiple inflammatory pathways and the production of a variety of different inflammatory cytokines and chemokines (Ndeupen et al, 2021). The inflammatory nature of the LNPs is crucial for the induction of adaptive immune responses because the mRNA alone did not induce detectable levels of adaptive immune responses ( Suppl.…”

“…The nucleoside-modified and purified mRNAs do not induce strong inflammatory responses (Karikó et al, 2005, 2008, 2011). Still, the ionizable lipid component of these LNPs is highly inflammatory, causes rapid and robust neutrophil infiltration to the injection site, and was responsible for the development of the inflammatory responses characterized by the presence of high levels of inflammatory cytokines and chemokines (Ndeupen et al, 2021).…”

PEGylation of mRNA by Hybridization of Complementary PEG-RNA Oligonucleotides Stabilizes mRNA without Using Cationic Materials

“…The complexation strategy exhibits potent outcomes in Pharmaceutics 2021, 13, 800 2 of 10 efficient mRNA delivery. However, as cationic materials interact with anionic biomacromolecules, such as glycosaminoglycans on the cell surface [14], cationic carrier components frequently damage cells and tissues [15][16][17]. Furthermore, complexed mRNA can be kicked out by the exchange reaction with anionic biomacromolecules, leading to enzymatic degradation of mRNA.…”