Plesiomonas shigelloides infection induced ferroptosis and apoptosis in hepatopancreas of zig-zag eel (Mastacembelus armatus)

The zig-zag eel (Mastacembelus armatus) is a commercially important fish species in southern China, yet its susceptibility to Plesiomonas shigelloides (P. shigelloides) infection remains poorly understood. In this study, 100 μL of YY001 (1 × 10⁹ CFU/mL) was used to intraperitoneally infect the zig-zag eel, and its effect on the hepatopancreas of the M. armatus was observed. The histopathology analysis of hepatopancreas revealed hemorrhage, tissue loosening, enlarged intercellular spaces, and increased cellular vacuolation. Transcriptomic profiling identified 5508 differentially expressed genes (DEGs), with significant enrichment in immune and metabolic pathways, especially in ferroptosis and apoptosis pathways, and these genes were upregulated in the infection group. Subsequently, we confirmed these findings through biochemical assays, TUNEL staining and qPCR. The results showed that GPX activity in hepatopancreas of M. armatus was significantly decreased, and iron ion (Fe) concentration and malondialdehyde (MDA) were significantly increased after infection. Furthermore, the results of gpx4 and scl7a11 genes expression in hepatopancreas of the M. armatus was significantly downregulated after infection, while the expression of ferroptosis marker genes lpcat3 and ncoa4 was significantly up-regulated. These results indicate that ferroptosis occurred in the hepatopancreas cells of the M. armatus after infection with P. shigelloides. The results of TUNEL staining showed that after infection with P. shigelloides, apoptosis occurred in the hepatopancreatic cells of the zig-zag eel, and the expressions of the apoptosis genes casp3, casp8, and bax genes were significantly upregulated, while the expression of the apoptosis inhibitor gene bcl2 was significantly downregulated. These results all indicate that P. shigelloides infection can cause ferroptosis and apoptosis in the hepatopancreas of the zig-zag eel, leading to hepatopancreatic lesions. Our study provides new insights into the pathogenesis of fish diseases caused by P. shigelloides.