Background and aims: The efficacy and underlying mechanisms of exclusive enteral nutrition (EEN) in adult patients with Crohn’s disease (CD) remain controversial. This study aimed to evaluate the role of EEN in adult patients with CD and to explore the mechanisms from the perspective of immunoregulation. Methods: This is a prospective, open-label pilot study. Active patients with CD were enrolled and prescribed an amino-acid-rich elemental diet for 12 weeks. Dynamic changes in immune cells, including neutrophils, monocytes, T cells and B cells, were detected by flow cytometry. Plasma cytokines were evaluated by ELISA. Results: Twenty adult patients with CD were enrolled. Among them, 1 discontinued treatment due to poor compliance, and 19 patients were included for final analysis. Clinical remission was achieved in 47.37% (9/19), 63.16% (12/19), and 73.68% (14/19) patients at weeks 4, 8, and 12, respectively. Endoscopic remission and transmural healing were achieved in 52.63% (10/19) and 15.79% (3/19) patients at week 12. Notably, there was no significant difference in clinical remission between week 4 and week 8 (p = 0.33) or week 12 (p = 0.09). Furthermore, we observed a rapid reconstitution of immunologic homeostasis as early as week 4. At week 4, both the frequency and activation of neutrophils and monocytes were decreased after EEN therapy. Significant decreases in Th17 cells and naïve B cells, increases in memory B cells, and regulatory B cells were also detected. These changes remained stable at weeks 8 and 12. Conclusions: EEN with an amino-acid-rich elemental diet orchestrated immunological balances and induces clinical remission in adult CD patients as early as week 4, suggesting a 4-week EEN therapy may be feasible and practicable in clinical practice.

Background/Aims: Data on the natural course of Chinese patients with ulcerative colitis (UC) was lacking. This study aimed to evaluate the natural history and prognosis of patients with UC in the past 15 years in China.Methods: This cohort study included patients with UC in a tertiary hospital in southern China from 2007 to 2021 (cohort I: 2007–2011, cohort II: 2012–2016, cohort III: 2017–2021). Patients’ clinical characteristics and natural history were analyzed retrospectively.Results: Of 1,139 included patients, 683 patients presented with proctitis or left-sided colitis at diagnosis and 38.5% of them (263/683) developed proximal disease extension. Fifty-eight percent of patients experienced relapse, chronic continuous and intermittent active course. Five patients (0.4%) developed colorectal tumors/dysplasia. The overall surgery rate was 8.6%, and the rates were 14.2%, 7.8%, and 8.0% in the 3 cohorts, respectively (P=0.059). Average time from diagnosis to surgery decreased from cohorts I to III (144 months vs. 36 months, P<0.001), so did the use of glucocorticoids (58.2% vs. 43.5%, P<0.001) and immunosuppressants (14.1% vs. 13.4%, P=0.016), and days of hospitalization (13 days vs. 9 days, P<0.001). Biologics were used more frequently during the first year (0.8%, 2.1%, and 13.7% for cohorts I to III, respectively; P<0.001). The rate of mucosal healing increased over time.Conclusions: In Chinese UC patients, one-third of patients experienced proximal disease extension. The rates of malignancy and mortality were low. More biologics were used, while use of immunosuppressants and glucocorticoids were reduced over time. Early biologics use seemed to promote mucosal healing, but the rate of colectomy has not dramatically decreased.