Comparative proteomic analysis indicates differential responses to fumonisin B1 (FB1) and hydrolysed fumonisin B1 (HFB1) in IPEC-J2 porcine epithelial cells in vitro

The intestinal epithelium is frequently exposed to environmental contaminants such as fumonisins, mycotoxins implicated in the development of mycotoxicosis across various mammalian species, with fumonisin B₁ (FB₁) being the most prevalent and toxic congener. Fumonisin B₁ (FB₁) can be enzymatically hydrolysed to produce hydrolysed fumonisin B₁ (HFB₁) that displays reduced inhibitory activity toward ceramide synthase. Given the central role of ceramide synthase in sphingolipid metabolism and cellular homeostasis, the reduced inhibitory activity of HFB₁ is considered toxicologically favourable, as it is less likely to disrupt membrane integrity and critical signalling pathways. However, the toxicity of HFB₁ remains variable across different in vitro and in vivo models. In this study, we evaluated the impact of FB₁ and HFB₁ on cell viability, apoptosis, and proliferation in the porcine intestinal cell line (IPEC-J2), including inflammatory responses through interleukin 8 (IL-8). Molecular mechanisms and pathways influenced by FB₁ and HFB₁ exposure were investigated through proteomic and bioinformatic analyses. Differentially abundant proteins (DAPs) were identified and functionally characterised using Gene Ontology analysis based on the Sus scrofa (domestic pig) database, revealing 52 significant DAPs between FB₁ and HFB₁ treatments compared to the control. Fibronectin 1 (FN1), an adhesive glycoprotein of the intestine, was consistently detected as a DAP in cells exposed to FB₁ and HFB₁. FB₁ upregulates FN1, while HFB₁ downregulates it, leading to different oncogenic pathways revealed by STRING enrichment analysis. Proteomic analysis further revealed distinct DAPs following FB₁ and HFB₁ exposure, implicating alterations in immune modulation (e.g. differential regulation of CD276), iron homeostasis (upregulation of FTL and FTH1), epithelial integrity (downregulation of NTN4, ST14), extracellular matrix remodelling (reduced SPARC), and angiogenesis-related pathways (decreased TINAGL1, FBLN2, SDC4) suggesting early changes in cellular signalling, stress response, and structural regulation that may be relevant to cancer biology and warrant further investigation. These findings also demonstrate that HFB₁ activates distinct cancer-related pathways in vitro compared to FB₁, with in vivo studies suggesting divergent mechanisms. HFB₁ also induces more extensive protein expression changes in IPEC-J2 cells, as reflected by the greater number of DAPs and the complexity of enriched pathways. However, further investigation is needed to determine whether these changes directly contribute to cytotoxicity or represent compensatory cellular responses.