CARBONIC-ANHYDRASE-I REDUCTION IN COLONIC MUCOSA OF PATIENTS WITH ACTIVE ULCERATIVE-COLITIS

Ulcerative colitis (UC) is associated with low intracolonic pH and unb alanced transmucosal tonic exchanges. Along the gastrointestinal tract carbonic anhydrase isoenzyme I (CA-I) is specifically expressed in co lon epithelium and is involved in mucosal control of ion, fluid, and a cid-base balance. Since altered CA-I expression may play some role in UC, CA-I was measured at the mRNA and protein level and carbonic anhyd rase (CA) enzyme activity was determined in colon biopsies of 14 UC pa tients (6 remission, 4 mild, 4 moderate UC) and of 12 healthy subjects . Patients with mild or moderate UC showed a significant reduction of CA-I mRNA and protein and of total CA activity in the inflamed mucosa compared to controls. Patients with UC in remission showed a pattern o f CA-I expression and CA activity similar to controls. This is the fir st report showing a reduction in the expression of CA-I in active UC.