Antiphospholipid antibody-associated NETosis is palmitoylation-dependent 2047

Abstract Description Antibodies targeting the phospholipid-binding protein beta-2 glycoprotein I (anti-β2GPI) are associated with thrombosis and inflammation in antiphospholipid syndrome (APS). Anticoagulation inconsistently prevents thrombosis and fails to mitigate long-term organ damage. There are limited treatment options for anticoagulant-resistant APS manifestations. We have previously shown that anti-β2GPI activate neutrophils through Toll-like receptor 4 (TLR4) to promote the release of pathogenic neutrophil extracellular traps (NETs), contributing to inflammation and thrombosis. Here, we sought to elucidate the mechanisms by which anti-β2GPI fully leverage TLR4 signaling to activate neutrophils. RNA-seq of APS neutrophils revealed upregulation of several members of the zDHHC family of enzymes, which facilitate protein palmitoylation, prompting us to further investigate the role of palmitoylation in the neutrophil response to anti-β2GPI. Palmitoylation inhibition with cyano-myracrylamide (CMA) mitigated neutrophil activation and NET formation downstream of anti-β2GPI and other TLR4-stimuli. Conversely, palmitoylation inhibition did not affect PMA-induced NETosis, highlighting a role of palmitoylation in TLR4-mediated NETosis, rather than NETosis more broadly. These findings indicate the potential of palmitoylation-associated proteins as novel therapeutic targets in APS. Ongoing work aims to identify the particular zDHHC-family and palmitoylated-target proteins implicated in these pathways. Funding Sources Supported by T32AI007413 Topic Categories Basic Autoimmunity (BA)