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

Abstract

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.