Clinical and endoscopic data
The demographic and clinical characteristics of the patients are shown in Table. Median age of the patients was 37 years (range, 21–64 years). Only one patient was smoker at the time of endoscopy. Eleven patients underwent ileocolonoscopy 6 months after ileo-colonic resection. Of these patients, 7 (63.6%) had endoscopic recurrence while in the remaining 4 (36.4%) there was no endoscopic lesion. Four out of these 11 (36.6%) CD patients had a clinically active disease (Crohn disease clinical index, CDAI > 150) and all of them had endoscopic recurrence (i2-i4). The remaining 6 patients who participated in the study underwent endoscopy 12 months after the intestinal resection. At this time point, endoscopy was also performed in 2 out of the 4 patients who had no endoscopic recurrence at month 6 because they became symptomatic.
Table. Demographic and clinical characteristics of patients
Patients Characteristics | N = 17 |
Age Years, Median (range) | 37 (21–64) |
Sex, Male, N (%) | 14 (82%) |
Smoking habits, N (%) Yes No | 1 (6%) 16 (94%) |
CD duration Months, Median (range) | 180 (12–320) |
Age at diagnosis, N (%) A1: ≤ 16 years A2: 17–40 years A3: over 40 years | 1 (6%) 13 (76%) 3 (18%) |
CD behaviour, N (%) B1: inflammatory B2: Stricture B3: Penetrating | 0 11 (65%) 6 (35%) |
CD location, N (%) L1: Ileal L2: Colonic L3: Ileocolonic | 17 (100%) 0 0 |
Harvey Bradshaw index at time of endoscopy Median (range) Remission Active | 4 (2–9) 13 (76%) 4 (24%) |
CD medication at time of endoscopy No medication 5-aminosalicylic acid Corticosteroids Thiopurine alone TNFs alone | 1 (6%) 14 (82%) 0 2 (12%) 0 |
Smad7 + cells infiltrate the neo-terminal ileum of CD patients independently of the presence of endoscopic recurrence
Following ileocolonic resection, CD lesions almost invariably develop in the previously uninflamed mucosa of the neo-terminal ileum proximally to the ileocolonic anastomosis. (5–6) This post-operative state is an useful setting to investigate molecules, which could be relevant for triggering and/or amplifying the tissue-damaging immune response. Therefore, we collected biopsies from CD patients with or without endoscopic recurrence and examined the expression of Smad7 by immunohistochemistry. Smad7-positive cells were more evident in CD samples than in CTR. Such cells were abundantly present in CD mucosal samples independently of the presence of endoscopic recurrence in both the epithelial and lamina propria compartments (Fig. 1). Notably, in CD sections, Smad7 accumulated in the cytoplasm and nucleus of both epithelial cells and LPMC (Fig. 1C). Analysis of the Smad7-positive cells in each CD and CTR section revealed that the number of Smad7 + cells was significantly higher in samples taken from the neo-terminal ileum of CD patients without endoscopic recurrence, CD patients with endoscopic recurrence and patients with established disease than in normal CTR (Fig. 2A). Interestingly, the total number of Smad7 + positive cells per sample was higher in the groups of CD patients without endoscopic recurrence and patients with endoscopic recurrence than in the group of patients with established disease (Fig. 2A). This finding was also evident when analysis of the Smad7 + cells was restricted to the epithelial compartment (Fig. 2B). In the lamina propria compartment, Smad7 + cells were more abundant in CD samples than in CTR with no significant difference among the 3 groups of CD patients (Fig. 2C). Further analysis at the 2 time-points (i.e. 6 and 12 months after ileocolonic resection) selected to investigate the occurrence of the endoscopic recurrence showed no significant difference in the number of Smad7-expressing cells (Fig. 3).
Overall, these data indicate that, even in the absence of endoscopic lesions, the mucosa of the neo-terminal ileum of CD patients is marked by accumulation of Smad7-positive cells.
In the early stage of CD inflammation, expression of Smad7 correlates with the number of interferon-γ-secreting cells
We previously showed that the different, early phases of CD are marked by distinct mucosal profiles of cytokines. (8) In particular, before the appearance of endoscopic lesions, the mucosa of the neo-terminal ileum contains elevated levels of Th1-related cytokines and slightly increased IL-17A expression, while transition from this stage to endoscopic recurrence is characterised marked by abundance of Th1 cytokines and marked increase in IL-17A. Therefore, we assessed whether expression of Smad7 correlated with the number of cytokine-secreting cells. A significant correlation was found between the Smad7 expression and the number of IFN-γ-secreting cells but not with the number of IL-17A-producing cells (Fig. 4).