Tissue-embedded CD4⁺ plasticity defines mucosal immunity in Inflammatory Bowel Disease

CD4⁺ T helper (Th) cell responses to commensal microbiota are linked to Inflammatory Bowel Disease (IBD), yet how Th programs coexist and evolve in human tissues remains poorly defined. Here, we profiled CD4⁺ memory T cells in intestinal biopsies using immunological and histological approaches to map their phenotypes, functional states, and spatial relationships across disease states. A marked expansion of CD4⁺ T cells concomitant with a RORγt⁺ Th population with elevated T-bet expression was linked to progression of inflammation. Moreover, Foxp3⁺ cells co-expressing RORγt emerged within the inflamed niche, indicating regulatory–Th17 plasticity. Trajectory visualization revealed a potential branched differentiation path towards either regulatory or tissue-resident Th17-like fates, with both termini expressing activation and proliferation markers. Correlation network analysis connected pro-inflammatory CD4⁺ states to T-bet⁺Granzyme-B⁺ CD8⁺ subsets, indicative of crosstalk between helper and cytotoxic lineages. Histology corroborated this organization, showing frequent interactions between CD4⁺ and CD8⁺ cells in the lamina propria and epithelial border. In functional assays, TCR stimulation during active disease revealed broad suppression of CD4⁺ pro-inflammatory cytokines concomitant with expansion of Foxp3⁺ cells. Conversely, HLA-DR ⁺ CD38 ⁺ memory subset retained multifunctionality, producing elevated levels of pro-inflammatory cytokines. Together, these results provide insight into a dynamic, tissue-embedded CD4 landscape in IBD.