Impairment of mitochondrial acetoacetyl CoA thiolase activity in the colonic mucosa of patients with ulcerative colitis

• Published in: Gut Vol. 56; no. 11; pp. 1543 - 1549
• Main Authors: Santhanam, Srikanth, Venkatraman, Aparna, Ramakrishna, Balakrishnan S
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and British Society of Gastroenterology 01.11.2007; BMJ; BMJ Publishing Group LTD; BMJ Group
• Subjects: Acetyl-CoA C-Acetyltransferase - metabolism; Adolescent; Adult; Biological and medical sciences; Biopsy; Butyryl-CoA Dehydrogenase - metabolism; Colitis, Ulcerative - enzymology; Colitis, Ulcerative - etiology; Colon; Crohn's disease; Digestive system. Abdomen; Endoscopy; Enoyl-CoA Hydratase - metabolism; Enzyme kinetics; Female; Gastroenterology. Liver. Pancreas. Abdomen; Humans; Inflammation; Inflammatory Bowel Disease; Intestinal Mucosa - enzymology; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Mercaptoethanol - pharmacology; Metabolism; Middle Aged; Mitochondria; Mitochondria - enzymology; Mitochondrial Diseases - enzymology; Other diseases. Semiology; Oxidation-Reduction; Potassium; Rodents; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Studies; Tumors; Human; Rectal hemorrhage; Left; Mucosa; Right; Malignant tumor; Inflammatory disease; Colonic disease; Colon cancer; Biopsy; Colonoscopy; Digestive diseases; Intestinal disease; Colitis; Colon; Endoscopy; Ulcerative colitis
• ISSN: 0017-5749; 1468-3288; 1468-3288
• DOI: 10.1136/gut.2006.108449

Background and aims:Butyrate oxidation by colonocytes is impaired in ulcerative colitis. This study examined the activity of enzymes involved in butyrate oxidation in ulcerative colitis.Methods:Activities of mitochondrial acetoacetyl coenzyme A (CoA) thiolase, crotonase and β-hydroxy butyryl CoA dehydrogenase were estimated spectrophotometrically in rectosigmoid mucosal biopsies from patients with ulcerative colitis and Crohn’s colitis, and control subjects undergoing colonoscopy for colon cancer or rectal bleeding.Results:The activity of mitochondrial acetoacetyl CoA thiolase was decreased by 80% in ulcerative colitis (3.4 (0.58) μmol/min/g wet weight, n = 30) compared with control (16.9 (3.5), n = 18) and with Crohn’s colitis (17.6 (3.1), n = 12) (p<0.0001). The activity of two other mitochondrial butyrate oxidation enzymes—crotonase and β-hydroxy butyryl CoA dehydrogenase—as well as of cytoplasmic thiolase was normal in ulcerative colitis. Mitochondrial thiolase activity in ulcerative colitis did not correlate with clinical, endoscopic or histological indices of disease severity. Mitochondrial thiolase activity was reduced in the normal right colon mucosa of patients with left-sided ulcerative colitis. Enzyme kinetic studies revealed a lowered Vmax, suggesting inhibition at a site distinct from the catalytic site. Reduced thiolase activity in ulcerative colitis was returned to normal by exposure to 0.3 mM β-mercaptoethanol, a reductant. Using normal colon mucosal biopsies, redox modulation of thiolase activity by hydrogen peroxide, a mitochondrial oxidant, could be shown. A significant increase in hydrogen peroxide formation was observed in ulcerative colitis biopsies.Conclusion:A defect of mitochondrial acetoacetyl CoA thiolase occurs in ulcerative colitis. Increased reactive oxygen species generation in mitochondria of epithelial cells in ulcerative colitis may underlie this defect.