Y. Liu1, F. Kuehn1, R. Vasan1, E. Liu1, F. Adiliaghdam1, E. Samarbafzadeh1, R. Hodin1 1Massachusetts General Hospital,General And GI Surgery,Boston, MA, USA
Introduction:
Luminal contents play a crucial role in the induction and maintenance of intestinal inflammation. Patients with Crohn´s disease benefit from diversion of the fecal stream, with immediate recurrence of inflammation after restoration of intestinal continuity. Furthermore, pouchitis after ileo-anal anastomosis for ulcerative colitis does not occur prior to ostomy closure. These observations support the premise that exposure to factors within the fecal stream is a critical component in inciting phenotypic expression of inflammatory bowel disease (IBD). And, yet, the components within the fecal milieu that play a role in activating the inflammatory pathways still remain unknown. Recent data has demonstrated that levels of the anti-inflammatory mucosal defense factor Intestinal alkaline phosphatase (IAP) are reduced in colon biopsies of patients with IBD. The objectives are to examine the inflammatory properties of ileal fluid from patients with and without IBD. Our central hypothesis is that pro-inflammatory factors in intestinal contents activate inflammatory cascades in the intestinal epithelial lining and that targeting these factors/pathways can present novel therapeutic approaches to treat IBD.
Methods:
Ileal fluid samples from 46 ileostomy patients with and without IBD were collected in the surgical clinic at Massachusetts General Hospital, Boston. IAP Activity was measured using the para-Nitrophenylphosphate (pNPP) assay. The effluent was centrifuged and the supernatant assayed by ELISA for key pro-inflammatory cytokines. Human THP1 macrophages were exposed to the fluid from 23 consecutive patients and assayed for cytokine expression.
Results:
Ileal fluid from 46 patients (28 IBD, 18 non-inflammatory controls) with a median age of 58 years (range; 23-94) was collected and assayed. TNF-a levels were significantly higher in ileal fluid of IBD patients than in controls (33.4 ± 62.9pg/ml vs. 9.7 ± 7.6pg/ml; p < 0.05). IAP activity was significantly lower in patients with IBD compared to patients without underlying inflammatory disease (16.9 ± 6.1 U/mg protein vs. 21.0 ± 6.7 U/mg protein; p<0.05). The inflammatory response of THP1 cells exposed to ileal fluid supernatant showed an individual cytokine profile for each patient and did not correlate with the cytokine levels in the original sample or the underlying disease.
Conclusion:
Analysis of Ileal luminal contents showed significantly higher TNFa levels and lower IAP activity in patients with IBD. The individual inflammatory response profile of each patient could serve as a basis for determining the risk for recurring disease or pouchitis in stoma patients with IBD.