TRPA1 contributes to calcium signaling induced by synthetic lipid nanoparticles

TRPA1 is a polymodal ion channel receptor known for its role in nociception. TRPA1 can be activated by local mechanical perturbations in the surrounding plasma membrane (PM) by molecules that insert in the lipid bilayer. While lipid nanoparticles (LNPs) are widely utilized for therapeutic delivery, their acute effects on the plasma membrane (PM) and associated signaling pathways remain poorly characterized. Here, we tested whether TRPA1 function can be modulated by LNPs while interacting with the target cell plasma membrane. We found that LNPs induce irregular Ca 2+ transients in heterologous and native TRPA1-expressing cells, which may reflect stochastic LNP-PM interactions. By applying selective and non-selective TRPA1 inhibitors, we revealed that the cytosolic [Ca 2+ ] transients arise through several mechanisms: TRPA1-dependent Ca 2+ influx, TRPA1-independent Ca 2+ influx, and Ca 2+ mobilization from the endoplasmic reticulum. The responses to LNPs were enhanced by low extracellular pH, which we found to increase their effects on membrane fluidity, and is relevant for the therapeutic applications of LNPs in acidic tissue environments. Our results unveil a non-canonical TRPA1 activation mechanism, and reveal previously unrecognized effects of synthetic LNPs on intracellular Ca 2+ signaling that may be relevant for the development of LNP-based vaccines.