Increased Expression of Glutathione S-Transferase-π in the Islets of Patients with Primary Chronic Pancreatitis But Not Secondary Chronic Pancreatitis

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Abstract
The mechanism of tissue alteration in chronic pancreatitis (CP) is still unclear. Different hypotheses have been discussed, including increasing oxidant 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-transferase-pi (GST-pi), in the pancreatic tissue of patients with CP and compared it with the healthy pancreatic tissue from age-matched donors. Pancreatic tissue from patients with secondary CP resulting from ductal obstruction by pancreatic cancer (PC) was also examined. The percentage of cells immunoreacting with anti-GST-pi was counted within 15 randomly selected islets in each slide of the three groups. In all specimens, ductal and ductular cells, and in PC, cancer cells, expressed GST-pi in a moderate intensity. Acinar 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 substances, which are the substrate for GST-pi, and lend support to the hypothesis of oxidative stress as the cause of CP.