The expression of glutathione transferase mu in patients with inflammatory bowel disease

Glutathione transferases (GST) are a group of multifunctional enzymes important in the detoxification of many electrophiles and, in addition, fatty acid hydroperoxides, thus limiting tissue damage from oxidative free radical attack. Of the four classes of GST (alpha, mu, pi, and theta), a class mu isoenzyme, GST mu, is dominantly inherited and is expressed in approximately half of the population. GST mu expression was examined in patients with inflammatory bowel disease and correlated to clinical course, extension, and age of onset of the diseases.

GST mu can be measured as GST activity against trans-stilbene oxide. This GST activity was measured in whole blood in 179 patients with ulcerative colitis, 109 patients with Crohn's disease, and 449 age-matched controls.

Frequencies of GST mu expression were as follows: controls (n = 449, 51.2%), mild ulcerative colitis (n = 76, 47.3%), moderate ulcerative colitis (n = 43, 46.5%), and severe ulcerative colitis (characterized by colectomy) (n = 60, 36.7%). This trend was, however, not significant (p = 0.094). Patients with onset of the colitis before the age of 30 years (n = 91) had a lower frequency of GST mu expression (35.2%) than patients with a later onset (n = 88, 52.3%) (p < 0.05). This difference was more pronounced among the colectomized patients (19.4% versus 55.2%) (p < 0.01). In Crohn's disease, patients with colitis had a lower frequency of GST mu expression (n = 29, 31.0%) than controls; however, this was not statistically significant (p = 0.055). No difference was found with regard to age of onset.

We conclude that in patients with ulcerative colitis, lack of GST mu is related to early age of onset and a more severe clinical course leading to colectomy.