Subclinical intestinal inflammation in patients with Crohn's disease following bowel resection: a smoldering fire

Fecal lactoferrin is the direct expression of intestinal inflammation in Crohn's disease (CD). The aim of this study was to analyze the in vivo intimate correlation between intestinal and systemic inflammation in CD patients in clinical remission following bowel resection. The secondary end point was to evaluate the prognostic value of lactoferrin levels and serum cytokines in terms of need of surgery for recurrence in these patients.

Fecal lactoferrin and serum cytokine (interleukin (IL)-1beta, IL-6, IL-12, tumor necrosis factor (TNF)-alpha, and transforming growth factor (TGF)-beta1) levels were assessed; hematological and biochemical investigations were carried out, and Crohn's Disease Activity Index was evaluated in the 36 patients who had undergone bowel resection. The prognostic value of lactoferrin and cytokine levels in terms of surgical recurrence was assessed by re-calling patients after 24 months from the enrolment in the study.

All patients, evaluated after a follow-up of 36 +/- 5 months, were in clinical remission. Fecal lactoferrin levels were found to be significantly correlated with IL-6 (R = 0.431, p = 0.025) and C-reactive protein (CRP; R = 0.507, p = 0.007), while no correlation was observed between lactoferrin and IL-1beta, IL-12, TNF-alpha, or TGF-beta1. Reoperation for anastomotic recurrence tended to occur significantly more frequently in patients with higher IL-6 (p = 0.10).

Subclinical intestinal inflammation, expressed by fecal lactoferrin, seems to keep the systemic inflammation alive in CD patients through the IL-6-CRP cascade. IL-6 seems to be predictive of the outcome of CD patients undergoing surgery.