Background. Strictures are a common complication in Crohn’s disease (CD), found in more than 50% of patients. They are characterized by the excessive deposition of extracellular proteins in the tissue as a result of the chronic inflammatory process. The effect of anti-tumor necrosis factor alpha (TNF-α) therapy on the development of fibrosis is not yet fully understood. Aim. To investigate whether the degree of intestinal inflammation and fibrosis is correlated with preoperative anti-TNF-α therapy in patients with CD who are undergoing bowel resection. Methods. This unblinded, prospective, single tertiary center, pilot cohort study included all adult patients with CD who underwent elective, laparoscopic, or open intestinal resection. Preoperative investigations included measurement of blood TNF-α concentration, specific antidrug antibodies, and the concentration of selected inflammatory cytokines. Three pathologists independently examined the specimens and assessed the degree of inflammation and fibrosis. Results. Histopathological specimens from 10 patients with CD who underwent ileocecal or ileocolic resections were retrieved. Four of those patients were on anti-TNF-α treatment prior to surgery. The last dose of the anti-TNF-α agent was administered 1–9 weeks prior to bowel resection. Patients on anti-TNF-α treatment had a higher fibrosis score than controls (p=0.01). Anti-TNF-α treatment was not associated with an increase in CD68- or CD163-positive macrophages. There was no significant relationship between the time from the final preoperative anti-TNF-α dose to surgery and the fibrosis score. No significant association was found between the concentration of major inflammatory cytokines, including TNF-α, and the fibrosis score or degree of inflammation. Conclusions. Patients who underwent preoperative anti-TNF-α treatment had a higher fibrosis score than controls.

Background Strictures are a common complication in Crohn’s disease (CD), which are found in more than 50% of the patients. They are characterised by excessive deposition of extracellular proteins in the tissue as a result of the chronic inflammatory process. The effect of anti- TNF-α therapy on the development of fibrosis is not yet fully understood. The aim of the study was to investigate whether the degree of intestinal inflammation and fibrosis correlates with pre-operative anti-TNF-α therapy in patients with Crohn’s disease undergoing bowel resection. Methods This is an unblinded, prospective, multicentre cohort pilot study. All adult patients with Crohn’s disease, who underwent elective, laparoscopic or open intestinal resection were included. Pre-operative blood investigations included measurement of TNF- α concentration and specific drug antibodies in addition to the concentration of selected inflammatory cytokines. Three pathologists examined the specimens independently and assessed the degree of inflammation and fibrosis. Results Histopathological specimens from 10 patients with CD who underwent ileocecal or ileocolic resections were retrieved. Four of those patients were on anti-TNF-α treatment pre-operatively. The last dose of anti-TNF-α agents was administered within 1–9 weeks prior to bowel resection. Patients on anti-TNF-α treatment had higher fibrosis score than the controls (p = 0.01). Anti-TNF-α treatment was not associated with an increase in either CD68 or CD163-positive macrophages. There was no significant relationship between time from last anti-TNF-α dose to surgery, and fibrosis score. No significant association between the concentration of major inflammatory cytokines including TNF-α and fibrosis score or degree of inflammation was found. Conclusion Patients on anti-TNF-α treatment had higher fibrosis score than the controls.