SARS-CoV-2 SUD2core promotes neutrophil-mediated inflammation by disabling HEBP2-mediated restraint on granule exocytosis.

The molecular basis of neutrophil-driven immunopathology in severe coronavirus disease 2019 (COVID-19) remains poorly defined. Here, we identify the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) SARS-unique domain (SUD)2core domain as a direct binding partner of the neutrophil-associated protein heme binding protein 2 (HEBP2). We show that HEBP2 normally suppresses azurophilic granule exocytosis, whereas SUD2core recruits the E3 ligase LTN1 to ubiquitinate and degrade HEBP2, thereby activating the Rab27a-Synaptotagmin Like 1 (SYTL1) axis to promote granule release, NETosis, and pro-inflammatory cytokine secretion. In a human immuno-epithelial organoid co-culture model, SUD2core amplifies epithelial damage in an HEBP2-dependent manner. Importantly, two small-molecule compounds that disrupt the SUD2core-HEBP2 interaction effectively attenuate neutrophil-mediated inflammation. These findings reveal a viral strategy that dismantles host restraint on neutrophil effector functions and highlight the SUD2core-HEBP2 interface as a promising therapeutic target for COVID-19.