Rats with trinitrobenzensulphonic acid-induced colitis were treated daily with rectal administration of apple polyphenols 10鈭? M for 14 days. COX-2, TNF-伪, tissue transglutaminase and calpain in colon mucosa samples were assessed by reverse transcription-polymerase chain reaction and western blot analyses. To ascertain the role of tissue transglutaminase in mucosal healing, wounded rat fibroblasts were incubated with cystamine (a tissue transglutaminase activity inhibitor).
Colitis was associated with increased COX-2, TNF-伪, calpain, and tissue transglutaminase mRNA. The protein expression of COX-2, TNF-伪 and calpain was increased whilst tissue transglutaminase was decreased. Apple extract treatment reduced the severity of colitis (
The efficacy of apple extract is mediated by its effects on COX-2 and TNF-伪. The unbalance between calpain and tissue transglutaminase may play a role in colonic damage and future therapeutic interventions in ulcerative colitis can target this mechanisms.