Evaluation of colitis
The severity of colitis was evaluated by continuously weight change, colon length, disease activity score, macroscopic damage score, histological score and colonic cytokines levels following an established protocol 27.
For assessing disease activity score, two investigators scored the results by body weight loss, stool consistency and rectal bleeding in a double-blinded manner. The scores were quantified as follows: body weight loss on a scale of 0–5 for <5%, 5–10%, 10–15%, 15–20%, 20–25%, >25%, respectively; stool consistency on a scale of 0–2 for normal, soft, liquid, respectively; and rectal bleeding on a scale of 0–1 for absent, present, respectively.
For assessing macroscopic damage score, two investigators scored the results by presence of strictures and hypertrophic zones, adhesion areas and intraluminal hemorrhage in a double-blinded manner. The scores were quantified as follows: presence of strictures and hypertrophic zones on a scale of 0–3 for absent, one stricture, two strictures, more than two strictures, respectively; mucus on a scale of 0–1 for absent, present, respectively; adhesion areas between the colon and other intra-abdominal organs on a scale of 0–3 for absent, one adhesion area, two adhesion areas, more than two adhesion areas, respectively; intraluminal hemorrhage on a scale of 0–1 for absent, present, respectively; erythema on a scale of 0–2 for absent, presence of a crimsoned area < 1 cm2, presence of a crimsoned area > 1 cm2 , respectively; and ulcerations and necrotic areas on a scale of 0–2 for absent presence of a necrotic area < 1 cm2, presence of a necrotic area > 1 cm2, respectively.
For assessing colonic histology score, two investigators scored the results by epithelial surface damage, the loss of crypts and inflammatory infiltration in a double-blinded manner. The scores were quantified as follows: crypt damage on a scale of 0–4 for no damage, basal one-third damaged, basal two-thirds damaged, only surface epithelium intact, and entire crypt epithelium lost, respectively; depth of injury on a scale of 0–3 for no, mucosal, mucosal and submucosal, and transmural injury, respectively; and inflammatory infiltration on a scale of 0–3 for no, slight, moderate, and severe inflammation, respectively.