Inflammatory bowel diseases 2026: form, function and therapeutic considerations for the epithelial barrier.

Inflammatory bowel disease (IBD) has long been conceptualized as a disorder of dysregulated immunity, yet growing evidence highlights the intestinal epithelium as an active determinant of disease behavior and therapeutic response. This editorial synthesizes contributions in the current issue that collectively redefine IBD through a tissue-centric lens, emphasizing barrier integrity, epithelial lineage specialization, antigen sampling, innate immune amplification, and environmental modulation. While epithelial-targeted and gut-directed therapies are biologically compelling, their successful translation into clinical practice presents significant challenges related to disease selection, trial design, endpoint sensitivity, and expected effect size. Emerging approaches—including combination strategies, maintenance therapy, and enriched populations—offer pragmatic paths forward. Importantly, advances in non-invasive, localized monitoring and functional biomarkers may be as critical as the therapies themselves, enabling detection of incremental tissue-level responses that traditional endpoints often miss. Together, these themes underscore the need for context-aware therapeutic strategies and dynamic disease assessment to advance epithelial-focused innovation in IBD.