Tumour necrosis factor-related apoptosis-inducing ligand receptor deficiency (TRAIL-R−/−) enhances susceptibility to dextran sulphate sodium (DSS) -induced colitis. (a) Clinical scoring of wild-type (WT) (n = 9) and TRAIL-R−/− (n = 10) mice administered 2·5% DSS for 5 days. The clinical score is addition of stool and bleeding score. The maximum clinical score was 8 (P = 0·032). WT (n = 8) and TRAIL-R−/− (n = 10) mice were continuously administered 3% DSS in (b), (c) and (d). (b) Kaplan–Meier survival curve. The P-value was calculated according to the log-rank test. P < 0·001. (c) Median survival time. (d) Body weights on the day they were killed, shown as a percentage of the initial body weight. P < 0·001. (e) Representative haematoxylin & eosin staining of WT and TRAIL-R−/− mouse colons, from animals fed with or without 2·5% DSS for 5 days (left panels, magnification 100 ×; right panels, magnification 200 ×). Bar, 100 μm. (f) Histological injury score of DSS-induced colitis in WT (n = 4) and TRAIL-R−/− mice (n = 4). All mice were fed 2·5% DSS in water for 5 days. Histological analysis included the severity of inflammation, crypt damage and sub-mucosal oedema. The sum of the scores from these three parameters was defined as the total histological injury score. P-values of total histological score, inflammation, and crypt damage were < 0·001; oedema, P = 0·001.