Luminally polarized mural and vascular remodeling in ileal strictures of Crohn's disease.

Intestinal stricture, a major complication of Crohn's disease (CD), results from fibromuscular remodeling and expansion of the intestinal wall. The corresponding microanatomical alterations have not been fully described, hindering progress toward understanding their pathogenesis and devising appropriate treatments. We used tissue-specific staining and quantitative digital histomorphometry for this purpose. Serial histologic sections from 37 surgically resected ileal strictures and adjacent nonstrictured controls from patients with CD were evaluated after staining for smooth muscle actin, collagen (Sirius red), and collagen types I, III, and V. Overall mural thickening in strictures was increased 2.2 ±â€¯0.2-fold compared with nonstrictured regions of the same specimens. The muscular layer most altered was the muscularis mucosae (MM). Compared with the internal and external layers of the muscularis propria, (MP) which were expanded 1.9 ±â€¯0.2- and 1.3 ±â€¯0.1-fold, respectively, the MM was expanded 17.7 ±â€¯2.6-fold, reflecting the combined effects of architectural disarray, an 11.6 ±â€¯1.4-fold increase smooth muscle content, and elaboration of pericellular type V collagen. In contrast, the architecture of the MP was preserved and pericellular collagen was virtually absent; rather, fibrosis in this layer was limited to expansion of the intramuscular septa by collagen types I and III. The muscular arteries and veins within the strictured submucosa frequently exhibited eccentric, luminally oriented adventitial mantles comprising hyperplastic myocytes and extracellular type V collagen. We conclude that the fibromuscular remodeling which results in CD-associated ileal strictures predominantly involves the MM and submucosal vasculature in a luminally polarized fashion and suggests that mucosal-based factors may contribute to stricture pathogenesis.

Accelerated Infliximab Dosing Increases 30-Day Colectomy in Hospitalized Ulcerative Colitis Patients: A Propensity Score Analysis.

Background: Standard outpatient induction dosing of infliximab (IFX) may not be effective in hospitalized ulcerative colitis (UC) patients with higher inflammatory burden and colectomy risk. Our aim was to determine whether initial IFX induction dose affects 30-day colectomy rate and other disease-related outcomes. Methods: IFX-naive hospitalized UC patients receiving at least 1 inpatient 5 mg/kg (SD) or 10 mg/kg (HD) IFX induction dose were included. Baseline demographics and admission-related characteristics were documented. Propensity score based matching was used to control for provider bias introduced due to nonprotocolized choice of IFX dose. The primary outcome was 30-day colectomy; secondary outcomes included the need for an accelerated induction IFX (AD), length of stay (LOS), 90-day and 1-year colectomy, and complications. Results: Of 146 (120 SD/26 HD) patients included, 25 (17.1%) underwent colectomy by 30 days, 33 (22.6%) by 90 days, and 41 (28.1%) by 1 year. In 21 propensity score matched dyads (n = 42) treated with SD or HD, colectomy rates and LOS were similar. SD patients more often needed AD (23.8% vs. 0%, P = 0.048) and AD patients progressed to colectomy more rapidly within 30 days compared to non-AD (P = 0.001). Female sex and hypoalbuminemia were associated with significantly increased odds of needing AD on both univariate and multivariate analyses. Conclusions: In our propensity score based analysis, receiving accelerated IFX dosing after an initial SD infusion was associated with significantly higher 30-day colectomy rates in hospitalized acute UC patients. The most effective dosing strategy in this population remains unclear and prospective randomized studies are needed.