Gasdermin D-dependent neutrophil pyroptosis exacerbates Coxsackievirus A6-induced neuroinflammation through NET formation.

BACKGROUND

Coxsackievirus A6 (CVA6) is a nonenveloped, single-stranded RNA virus linked to neurological complications. Emerging evidence suggests neutrophil pyroptosis drives inflammation. However, the role of neutrophil pyroptosis in CVA6 pathogenesis remains unexplored.

METHODS

Ten-day-old wild-type (WT), Caspase-1 KO, and GSDMD KO mice were infected with a lethal dose of CVA6. For in vivo and in vitro studies, we used the caspase-1 inhibitor belnacasan, disulfiram, and anti-Ly6G antibody. We also generated neutrophil-specific PAD4-knockout mice (PAD4 Ne-KO) by deleting Padi4 under the S100A8 promoter. Post-infection, clinical scores, survival, and body weight were monitored. Brain tissues and bone marrow-derived neutrophils (BMDNs) were collected for analysis. Key methods included qPCR, Western blotting, histology/immunofluorescence, flow cytometry, and TEM to assess pyroptosis, inflammation, and immune cell infiltration. Findings were further validated using blood samples from HFMD patients.

RESULTS

In this study, we investigated how the Caspase-1/GSDMD pathway mediates neutrophil extracellular trap (NET) release and drives CVA6-induced neuroinflammation. CVA6 infection increased neutrophil numbers in mouse brain and peripheral blood, along with elevated MPO-DNA-a NET marker. In BMDNs, degranulation and NET formation occurred by 24 hpi, accompanied by Caspase-1/GSDMD activation. Caspase-1 knockout prolonged survival and reduced GSDMD-N expression in brain neutrophils; pharmacological Caspase-1 inhibition decreased mature IL-1β and IL-18 in brain tissue and suppressed CVA6 replication in BMDNs. Together, in vitro and in vivo data indicate that Caspase-1/GSDMD activation and NETosis critically contribute to CVA6-induced brain injury. This was confirmed by GSDMD knockout or disulfiram-mediated GSDMD inhibition, both of which markedly reduced NET release and neuropathology. Notably, global neutrophil depletion worsened infection-suggesting a protective role-whereas neutrophil-specific PAD4 knockout improved survival. Clinically, GSDMD expression showed a significant positive correlation with NETosis markers in patient samples from CVA6-infected individuals.

CONCLUSION

These findings enhance understanding of enteroviral pathogenesis, identify GSDMD as a promising therapeutic target, and provide a novel framework for developing precision interventions that reduce excessive inflammation without impairing essential host defenses.