It is well accepted that fecal S100A12 (FS) is a non-invasive biomarker, which reflects mucosal inflammation in ulcerative colitis (UC). However, it has not been well studied whether FS can predict treatment response during the early phase of remission induction therapy. Therefore, we monitored FS levels during remission induction treatment and assessed the within-day variability to evaluate the usefulness of FS as a reliable predictor of early response to remission induction treatment in patients with active UC.Methods:
(1) Twelve consecutive patients diagnosed with active UC undergoing induction treatment (prednisolone 8, tacrolimus 3, adalimumab 1) were included in the study. FS and clinical activity scores (Lichtiger index: LI) were prospectively followed up for 4 weeks. Clinical response was defined based on LI. FS was measured using ELISA Kit provided by Cysbio Bioassays. (2) Within-day variability was assessed by collecting fecal samples 4 times a day from patients with active UC (n = 6). A coefficient of variation was calculated for each sampling day. Data are shown as median with interquartile ranges in parentheses.Results:
(1) FS showed a significant reduction at 4 weeks after treatment in clinical responders (n = 10, FS before versus 4 weeks after treatment, 9.7 (5.3–15.4) versus 0.5 (0.0–2.7) μg/g). In these clinical responders, LI was rapidly decreased from 1 week after treatment, however, FS was not decreased significantly at 1 and 2 weeks after treatment (before versus 1 week after treatment, LI, 12 (11–13) versus 6 (2–9), P < 0.05; FS, 9.7 (5.3–15.4) versus 5.5 (1.3–20.2) μg/g, P = 0.70). (2) FS levels fluctuated within a single day in patients with active UC. The median coefficient of variation of FS within a day was 98.6 (73.9–200.0).Conclusions:
FS is a useful biomarker to predict treatment response in patients with active UC. However, it is not sensitive enough to detect the early change within 2 weeks after remission induction treatment possibly because of the large within-day variability.