FoxO4 reduces the damage and mechanism of PEDV-infected IPEC-J2 cells through the NF-κB/MLCK pathway.

Porcine epidemic diarrhea (PED) incurs substantial economic losses to the pig industry. During viral infection of cells, the activity of NF-κB is upregulated. As an endogenous inhibitor, FoxO4 plays a crucial role in antagonizing NF-κB activity, inhibiting the NF-κB-mediated MLCK signaling pathway, altering the expression of cellular tight junctions (TJs) and pro-inflammatory cytokines, and protecting intestinal epithelial cells from damage. However, there are limited reports on this inhibitory and protective effect in PEDV-infected IPEC-J2 cells. Therefore, this experiment employed methods such as homologous recombination, qRT-PCR, Western blotting, co-immunoprecipitation, laser confocal microscopy, and cell transmembrane resistance assays to investigate the effect of FoxO4 on indicators related to cell damage through the NF-κB/MLCK pathway in infected cells. The results demonstrated the successful construction of FoxO4 and NF-κB factor p65 expression vectors, confirming the interaction between the two in IPEC-J2 cells. FoxO4 effectively antagonizes the expression of NF-κB/MLCK pathway factors in infected cells, and through this action, it reduces the permeability of infected cells, maintains the integrity of the cell membrane, upregulates the expression of TJ proteins, antagonizes the expression of pro-inflamma-tory factors, and exerts effects in promoting cell apoptosis and antagonizing viral replication.This study further elucidates the molecular mechanisms underlying cell damage caused by PEDV and offers new potential targets for protecting intestinal epithelial barrier function.