TNBS-induced colitis and histological analysis

The mice were presensitized with 1% (wt/vol) TNBS that was diluted in acetone and olive oil and applied to the abdomen of mice. Seven days later, the mice were rectally injected with TNBS (200 mg/kg) in 50% ethanol through a catheter inserted into the colon, as previously described.²⁴ Mice were sacrificed 4 days after the TNBS injection.

Mouse colon tissue was fixed in 10% formalin and embedded in paraffin. Cut tissues were stained with hematoxylin and eosin (H&E). Histological scores were assessed blindly using criteria that have been previously described.^25,26 Briefly, 0=no inflammation, 1=moderate mucosal inflammation without erosion or ulceration, 2=increased mucosal inflammation with erosion, 3=increased mucosal inflammation with ulceration (<1 mm), and 4=increased mucosal inflammation with ulceration (>1 mm).