Caspase-8 activation regulates enterovirus D68 infection-induced inflammatory response and cell death

Enterovirus D68 (EV-D68) infection causes severe acute respiratory infection and serious neurological complications, such as acute flaccid myelitis (AFM), in children. However, although EV-D68 has pandemic potential, no effective drugs or vaccines are currently clinically available. Furthermore, EV-D68 infection-induced inflammatory response and cell death are not fully understood. In this study, we demonstrated that several inflammatory cytokines were upregulated in a multiplicity of infection (MOI) dependent manner in EV-D68-infected human rhabdomyosarcoma (RD) cells. Quantitative reverse transcriptase PCR (qRT–PCR) confirmed TNF-α, IL-6, CCL-5, and CXCL-5 mRNA levels were highly upregulated after EV-D68 infection. IL-1β processing and maturation mediated by caspase-8 was inhibited by the caspase-8 inhibitor Z-IETD-FMK. EV-D68 infection activates caspase-8 to mediate IL-1β maturation and secretion. Additionally, EV-D68 activated cell death-related proteins such as caspase-3, PARP-1, pMLKL, and GSDME. Thus, EV-D68 infection activates caspase-8, which triggers the necroptosis and apoptosis pathways. Overall, our data suggest that caspase-8 activation is associated with the inflammatory response and cell death in EV-D68-infected RD cells. This mechanism represents a novel target for treating EV-D68 infection by inhibiting caspase-8 activation.