Study population: clinical and endoscopic data
Seventeen CD patients (male, 82%) who underwent ileocolonic resection for a chronically active disease poorly responsive to medical treatment were included in this study. The demographic and clinical characteristics of the patients are shown in Table 1. Median age of the patients was 37 years (range, 21-64 years). Only one patient was smoker at the time of endoscopy. In all these patients, lesions (herein termed late/established CD) were confined to the terminal ileum. At the time of surgery, 9 patients were on steroids, and 2 of them were taking simultaneously azathioprine, while 2 patients had previously received anti TNF-α. Mucosal samples were collected from the resected ileum of 11/17 patients [8 male; median age 53 (21–69) years, median disease duration 149 (36-312) months]. In the remaining 6 patients, mucosal samples were not available as surgeries were performed in urgency.
At the time of ileocolonoscopy, 14 out of 17 patients (82%) were receiving mesalamine and 2/17 (12%) patients were received thiopurines. Eleven patients underwent ileocolonoscopy 6 months after ileo-colonic resection. Of these patients, 7 (63.6%) had endoscopic recurrence (4 pts with Rutgeerts score i2 and 3 pts with Rutgeerts score i4) while in the remaining 4 (36.4%) there was no endoscopic lesion (Rutgeerts score i0-i1). Four out of these 11 (36.6%) CD patients had a clinically active disease (Harvey-Bradshow index, HBI>5) 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. One of these patients had no endoscopic recurrence i0 and the remaining 5 had endoscopic recurrence: Rutgeerts score i2 in 4 patients and i4 in 1 patient. Additionally, endoscopy was performed at 12 months in 3 out of the 4 patients who had no endoscopic recurrence at month 6 because they became symptomatic: 2 out of these 3 patients developed endoscopic recurrence (Rutgeerts score i3 in 1 patients and i2 in the other one). Endoscopy was also performed at month 12 for a worsening of symptoms in 4 patients, who had endoscopic lesions (grade i2 according to Rutgeerts) at month 6; in all these patients, the second endoscopy evidenced severe endoscopic recurrence (Rutgeerts score i3-i4).
Table. Demographic and clinical characteristics of patients
Patients Characteristics
|
CD pts
|
Control pts
|
n=17
|
n=5
|
Age years, median (range)
|
37 (21-64)
|
38 (28-55)
|
Sex male, N (%)
|
14 (82%)
|
2 (40%)
|
Smoking habits, N (%)
Yes
No
|
1 (6%)
16 (94%)
|
1 (20%)
4 (80%)
|
CD duration months, median (range)
|
180 (12-320)
|
na
|
Age at diagnosis, N (%)
A1: £ 16 years
A2: 17-40 years
A3: over 40 years
|
1 (6%)
13 (76%)
3 (18%)
|
na
|
CD behaviour, N (%)
B1: inflammatory
B2: Stricture
B3: Penetrating
|
0
11 (65%)
6 (35%)
|
na
|
CD location, N (%)
L1: Ileal
|
17 (100%)
|
na
|
Harvey Bradshaw index at time of endoscopy a
Median (range)
Remission
Active
|
4 (2-9)
13 (76%)
4 (24%)
|
na
|
Rutgeerts score at 6 month after surgery b
No CD recurrence (i0-i1)
CD recurrence (i2-i4)
No endoscopy
|
4 (24%)
7 (41%)
6 (35%)
|
na
|
Rutgeerts score at 12 month after surgery b
No CD recurrence (i0-i1)
CD recurrence (i2-i4)
No endoscopy
|
2 (12%)
13 (76%)
2 (12%)
|
na
|
CD medication at time of endoscopy
No medication
5-aminosalicylic acid
Corticosteroids
Thiopurine alone
TNFs alone
|
1 (6%)
14 (82%)
0
2 (12%)
0
|
5 (100%)
0
0
0
0
|
- Adapted from Harvey-Bradshaw index
- Adapted from Rutgeerts score
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-g-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).