Fiallos, E.; Cociancic, P.; Esteban, J.-G.; Munoz-Antoli, C.; Toledo, R.

Background: Intestinal helminth infections trigger complex host responses, determining parasite survival and tissue homeostasis. Primary Echinostoma caproni infection disrupts epithelial metabolism, differentiation, and repair in an IL25 deficient environment, as shown in a previous study by our research group; however, the adaptive mechanisms during homologous superimposed infections remain unclear. Methodology and Principal findings: Male ICR mice were assigned to control, primary infection, and homologous superimposed infection groups, and ileal epithelial cells were isolated for proteomic profiling using liquid chromatography tandem mass spectrometry (LC-MS/MS) with data dependent acquisition (DDA) and sequential window acquisition of all theoretical mass spectra (SWATH). Differential protein expression was analyzed with Elastic Net regression, partial least squares discriminant analysis, and fold change ranking, while functional enrichment and protein-protein interaction networks were explored using gene set enrichment analysis (GSEA) and STRING. Notably, homologous superimposed infection revealed proteomic signatures associated with lysosomal and peroxisomal lipid metabolism, PPAR pathway activation, cytoskeletal reorganization, epithelial barrier reinforcement, a specialized antimicrobial peptide repertoire, and interactions between IgE receptor associated proteins, consistent with a restoration of intestinal homeostasis influenced by IL25. Conclusions: Host adaptation to repeated E. caproni exposure involves coordinated metabolic, signaling, and tissue repair responses that partially restore intestinal homeostasis, with IL25 emerging as a central regulator linking metabolic reprogramming, epithelial integrity, and antihelminth immunity, thereby providing a proteomic framework for understanding how repeated helminth exposure drives partial resistance through integrated epithelial and immunometabolic adaptations.