Insulin preservatives trigger neutrophil extracellular trap formation through SYNE1-mediated nuclear disassembly

Abstract

Neutrophil extracellular traps (NETs) are critical effector molecules in sterile inflammation, yet the molecular mechanisms by which xenobiotic chemical exposures trigger NETosis remain poorly defined. Here, using phenolic preservatives present in all FDA-approved insulin formulations as a discovery platform, we show that these compounds induce NETosis in primary human neutrophils (34.3 {+/-} 5.0% vs. 2.8 {+/-} 0.9% for preservative-free insulin; p < 0.001) via a mechanism distinct from canonical PKC- and calcium-dependent pathways. Data-independent acquisition mass spectrometry (n = 6 donors) reveals that preservatives prompt coordinated dephosphorylation of SYNE1 (nesprin-1) at Ser8724 and Ser8727 (log2FC = -4.41 and -4.01, respectively; both q-value < 0.0001), disrupting LINC complex-mediated nuclear-cytoskeletal anchoring, through a phosphatase-dependent pathway distinct from canonical PKC- and calcium-dependent NETosis. In a porcine subcutaneous catheter model, preservative-containing formulations drive progressive NET accumulation, neutrophil infiltration, and early fibrotic changes over 7 days, whereas removing preservatives reduces the histological inflammation score by 40% (P < 0.001). These findings establish phenolic preservatives as non-pathogen triggers of NETosis, identify disruption of the SYNE1-LINC complex as the underlying mechanism, and demonstrate that preservative-free formulations lessen device-related inflammation, offering a translatable strategy for safer implantable drug delivery systems.