Cepharanthine mitigates NIBV-induced pyroptosis via the MDA5/NF-κB/NLRP3 signaling pathway

This study elucidates the mechanism through which cepharanthine (CEP) mitigates NIBV-induced pyrodeath in renal tubular epithelial cells by modulating the MDA5/NF-κB/NLRP3 signaling pathway. Primary renal tubular epithelial cells (RTECs) were isolated from one-day-old Hy-Line Brown chicks and subsequently assigned to four groups. The C+CEP and N + CEP groups received 0.5 μM CEP, while the NIBV and N + CEP groups were exposed to 1 MOI of the SX9 strain of NIBV. The study shows that CEP significantly reduces NIBV load (P < 0.05) and decreases the mRNA and protein levels of MDA5/NF-κB/NLRP3 signaling components, such as MDA5, ISP-1, TRAF6, TAK1, NF-κB, IKKα, IKKβ, NLRP3, caspase-1, IL-1β, and IL-18, upon NIBV infection (P < 0.05 or P < 0.01). Moreover, CEP markedly reduced cellular pyroptosis (P < 0.001) and lactate dehydrogenase (LDH) activity (P < 0.01). Flow cytometry and fluorescence-based assays corroborated these findings, revealing a substantial diminution in pyroptosis post-NIBV infection in CEP-treated cells (P < 0.01). Laser confocal microscopy revealed a clear decrease in NLRP3-associated red fluorescence foci after CEP treatment. These results highlight that CEP could mitigate NIBV-induced pyroptosis in RTECs by modulating the MDA5/NF-κB/NLRP3 signaling pathway.