Dietary DINCH exposure is associated with altered intestinal homeostasis under high-fat diet-induced metabolic stress in a sex-dependent manner.

Metabolic disorders such as obesity are driven by complex interactions between diet and environmental exposures, yet the impact of emerging plasticizers on intestinal homeostasis remains unclear. Di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH), introduced as a safer alternative to phthalates, may contribute to metabolic reprogramming, particularly under high-fat diet (HFD) conditions. Building on findings of systemic metabolic and immune alterations, this study investigates whether DINCH exposure affects intestinal macroscopic morphology, mucosal immune homeostasis, and epithelial barrier-associated gene expression under HFD-induced metabolic dysregulation in a sex-dependent manner. Using male and female mice exposed to HFD with or without DINCH, we performed analysis of intestinal morphology, mucosal and systemic immune cell populations, and barrier-associated gene expression. DINCH exposure modified HFD-induced intestinal remodelling, as evidenced by increased colon length compared to HFD only controls, suggesting altered intestinal adaptation under metabolic stress. Immunological profiling revealed sex-specific effects, with females showing restricted systemic immune modulation characterized by reduced splenic Th2 cells. In contrast, males exhibited broader changes, including increased Th1 and Th17 cell populations in Peyer's patches, indicating enhanced mucosal pro-inflammatory immune activation. DINCH exposure was associated with altered expression of genes involved in epithelial homeostasis in ileum of male mice. Specifically, the tight junction genes Cldn8 and Ocln were downregulated, while Tff3, involved in epithelial repair, and the barrier-associated gene Muc2 were upregulated, indicating transcriptional alterations related to epithelial homeostasis and stress. Importantly, these changes were transcriptional only and provide no structural or functional evidence of intestinal barrier impairment. In contrast, females showed fewer epithelial transcriptional alterations, supporting a sex-dependent response to DINCH exposure. Collectively, DINCH exposure was linked to intestinal macroscopic morphology, immune balance, and barrier-related gene expression in a sex-dependent manner within an HFD background. These results extend prior evidence of systemic metabolic effects and identify the intestine as potential target of DINCH under obesogenic conditions.