Crohn’s disease–like intestinal fibrosis is IL-17A dependent. (A) Schematic representation of the generation of Rora^ΔRorc mice. (B) Absolute number and frequency of IL-17A⁺RORγt⁺ cells isolated from Peyer’s patches (n = 3–4 mice). (C) Experimental schematic outlining the study design. (D) Representative flow cytometry plots showing live CD45⁺Lineage⁻CD3⁻RORγt⁺ ILC3s in the mLNs (n = 3–4 mice). (E) Absolute number of live CD45⁺Lineage⁻RORγt⁺ ILC3s (n = 4–5 mice). (F) Frequency of Th17 cells within the CD4⁺ T cell population (n = 4–5 mice). (G)Il17a transcript levels in the cecum (n = 7–8 mice). (H)Il5 transcript levels in the cecum (n = 7–8 mice). (I)Il13 transcript levels in the cecum (n = 7–8 mice). (J) CFU counts from cecal samples (n = 7–8 mice). (K) Representative Masson’s trichrome–stained cecal tissue sections showing collagen deposition. Scale bar = 1,000 μm. (L) Quantification of collagen deposition in the cecum. (M) Measurement of mucosal thickness (n = 7–8 mice). WT mice refer to Rora^fl/fl littermate controls. Lineage markers: CD3ε, CD3, CD5, CD8α, TCRβ, Cd11b, CD11c, CD19, B220, Ly6C, Ly6G, Ter119. Data are representative of two independent experiments and are presented as the mean ± SEM. Statistical significance was determined using an unpaired two-tailed t test (*P < 0.05, **P < 0.01, ***P < 0.001; ns, not significant).