TLR4 recognizes the BNT162b2 vaccine's empty lipid nanoparticle to induce NF-𝞳B and IRF responses

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Presentation Time: 02:15 PM - 03:30 PM
Poster Board Number: B178
Abstract ID: 4205

Presenting Author:
Amanda E Zelkoski , Graduate Student at Uniformed Services Univ. of the Hlth. Sci., Henry M. Jackson Fndn. for the Advancement of Mil. Med.

Abstract:

Lipid nanoparticles (LNPs) are an integral part of messenger RNA (mRNA) vaccines, aiding in uptake and shielding mRNA from degradation. Studies indicate LNPs are capable of engaging Toll-like Receptors (TLRs), augmenting immune responses to vaccination. Our research sought to investigate TLR4 activation by the LNP component of the BNT162b2 mRNA vaccine and compared this response with that of the vaccine.

Using monocyte cell lines, we evaluated the innate signaling pathways activated by the LNP and mRNA vaccine in comparison to immune stimuli. The THP-1 reporter cell line displayed activation of Interferon Regulatory Factor (IRF) and Nuclear Factor-kappa Beta (NF-ⲕB) upon stimulation with LNP. NF-ⲕB activation was further assessed with the U937 cell line by western blot. Signaling is evident at 24 hours, peaking at 48 hours. Comparison of LNP and mRNA vaccine revealed similar responses. Moreover, we identified an important role for TLR4 by utilizing a TLR4-deficient THP-1 reporter cell, showing reduced response to LNP.

Our findings show that the LNP activates NF-ⲕB and IRF pathways in monocyte cell lines, with no additional stimulation from the mRNA component of the BNT162b2 vaccine.  Furthermore, our findings indicate that TLR4 engagement is a crucial mechanism in the innate response induced by the BNT162b2 LNP. Overall, these findings highlight the LNP’s role in triggering the innate immune response. Defining the mechanisms of immune activation could improve vaccine design.