Dear Editor,

We are pleased to read that Camus et al. find our paper on the altered secretory capacity of the right colon of UC patients in remission interesting in the context of colonic function and UC. In their comment to our paper, the authors suggest that the altered secretory capacity of the right colon could be due to the 5-ASA that the majority of UC patients use to keep the disease in remission. The background to this suggestion is that 5-ASA has been shown to cause diarrhea in a small group of UC patients, and that balsalazide, sulfasalazine, and olsalazine, but not mesalamine have been shown to induce a secretory response when added to ileal tissue in vitro.[1, 2] In our study, 19 of the 24 UC patients received 5-ASA, and the remaining 5 patients did not use any medication for their UC. The 5-ASA used was either Pentasa® or Asacol®, both with mesalamine as the active component, i.e. the substance that did not cause a secretory response in vitro. Due to the low number of patients that did not receive medical treatment for their UC, we did not divide the patients into treated and untreated. However, the altered secretory capacity in the right colon was also observed in the untreated patients. Although we cannot exclude that the 5-ASA treatment has an effect on the secretory capacity of the tissue, the fact that an altered response was observed also in the untreated patients, and that the 5-ASA used in this study was the type that did not induce secretion in vitro, suggest that the altered secretion in the right colon during UC is due to disease rather than 5-ASA. In their comment, Camus et al. also suggested that it would be interesting to compare patients with pancolitis to those with left-sided colitis. We agree that this would be a very interesting follow-up study that could answer the question ‘is the altered secretion in the right colon due to previous periods of inflammation in that particular segment?’


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