Nephropathogenic Infectious Bronchitis Virus-induced pyroptosis of chicken renal tubular epithelial cells via MDA5/NF-κB/NLRP3 signaling pathway

MDA5 is an innate pattern recognition receptor that is implicated in the recognition of various viruses. It can recognize RNA viruses, activate downstream signaling pathways, facilitate the transcription of inflammatory factors, and induce cell pyroptosis. Pyroptosis is a programmed cell death mode, accompanied by the release of inflammatory factors and inflammatory response. In this study, we hypothesize that pyroptosis is elicited by the signal cascade subsequent to MDA5 recognition of Nephropathogenic Infectious Bronchitis Virus (NIBV). Thus, we infected chicken renal tubular epithelial cells with NIBV and discovered that NIBV infection induced pyroptosis and upregulated the mRNA levels of MDA5. Consequently, we infected primary chicken renal tubular epithelial cells with NIBV and inhibited TRAF6 using the exogenous inhibitor C25-140. We found that NIBV could enhance lactate dehydrogenase (LDH) levels, increase the proportion of pyroptosis cells, and upregulate the mRNA and protein levels of the MDA5/NF-κB signaling pathway and the classical pyroptosis pathway. Here, we selected the ubiquitin ligase TRAF6, a key node in the MDA5/NF-κB signaling pathway, from molecular biological and genetic perspectives to explore the molecular mechanism of NIBV-induced pyroptosis. After using inhibitor C25-140, NIBV-induced apoptosis and MDA5/NF-κB/NLRP3 pathway were reversed. In addition, the amount of NIBV replication in the cells was reduced. In conclusion, the MDA5/NF-κB/NLRP3 signaling pathway is involved in the regulation of pyroptosis in a NIBV-infected chicken renal tubular epithelial cell model. Inhibition of this signaling pathway can alleviate NIBV-induced pyroptosis and reduce the replication of NIBV in cells, which may be one of the strategies for the treatment of NIBV.