Increased expression of glutathione S-transferase-pi in the islets of patients with primary chronic pancreatitis but not secondary chronic pancreatitis

The mechanism of tissue alteration in chronic pancreatitis (CP) is still un clear. Different hypotheses have been discussed, including increasing oxida nt stress in the acinar cells, often as a result of exposure to xenobiotics . To evaluate the role of oxidative stress in CP, the authors investigated the expression of the drug-metabolizing phase II enzyme, glutathione S-tran sferase-pi (GST-pi), in the pancreatic tissue of patients with CP and compa red it with the healthy pancreatic tissue from age-matched donors. Pancreat ic tissue from patients with secondary CP resulting from ductal obstruction by pancreatic cancer (PC) was also examined. The percentage of cells immun oreacting with anti-GST-pi was counted within 15 randomly selected islets i n each slide of the three groups. In all specimens, ductal and ductular cel ls, and in PC, cancer cells, expressed GST-pi in a moderate intensity. Acin ar cells did not stain. Various numbers of islet cells in each of the three groups were stained strongly. More islet cells expressed GST-pi in CP (42% ) than in healthy pancreatic tissue (16%, p < 0.001) or PC (17%, p < 0.001) . Our results imply an important role of islet cells in the metabolism of s ubstances, which are the substrate for GST-pi, and lend support to the hypo thesis of oxidative stress as the cause of CP.