Objective: To investigate the effects of adalimumab on the induction of complete endoscopic healing and normalization of mucosal cytokine gene expression in patients with active Crohn's disease.
Material and methods: A prospective, single-center study including 77 patients. All were examined by endoscopy before initiation of adalimumab induction therapy with a minimum of six adalimumab injections. Patients were treated until documentation of complete endoscopic healing. Biopsies for measurements of mRNA expression levels of interleukin(IL)-17A (IL17A), IL23, interferon-gamma (IFNG), tumor necrosis factor-alpha (TNF), IL10 and Forkhead Box P3 (FOXP3), as well as for immunohistochemistry (IHC) were sampled at pre- and post-treatment endoscopy, and from 17 control patients.
Results: Complete endoscopic healing was achieved in 27.3% after 10 weeks of treatment, documented by endoscopy at week 12. Cumulative endoscopic healing after 52 weeks was 44.2%. Complete endoscopic healing led to a significant reduction in mRNA expression levels for all cytokines except IL10. Elevated expression of TNF and IL-17A persisted in 52% and 76%, respectively, of patients with complete endoscopic remission. Pre-treatment cytokine gene expression levels did not predict response to adalimumab therapy.
Conclusions: Adalimumab induces accumulated complete endoscopic healing in 44% of patients after 52 weeks of therapy. Normalization of mucosal gene expression of cytokines does not occur in all patients with endoscopy-verified healed mucosa. Inclusion of normalized mucosal cytokine expression into the concept of mucosal healing could have an impact on long-term clinical outcome.