INTRODUCTION: Chronic pancreatitis (CP) is frequently associated with stone formation within the pancreatic duct system. The mechanism of pancreatic stone formation, however, is still unclear. AIMS: Osteopontin expression is related to urinary stone formation and several diseases associated with calcification such as atherosclerosis, breast cancer, and meningioma. We therefore hypothesized and studied whether that osteopontin may contribute to the formation of calculi in CP. METHODOLOGY: Twenty patients with CP who underwent elective surgery were included in the study. As controls, normal pancreas specimens were collected from five additional patients. We used reverse transcription polymerase chain reaction and reverse transcription in situ polymerase chain reaction to evaluate osteopontin mRNA expression and immunohistochemical staining to evaluate osteopontin-producing cells. RESULTS: No expression of osteopontin was seen in normal pancreas cells. Osteopontin expression was detected in acinar or ductal cells in all 11 cases of chronic calcifying pancreatitis, whereas in 5 of 9 CP cases without pancreatic stones there was no expression of osteopontin in acinar or ductal cells. The data revealed a high incidence of osteopontin expression in chronic calcifying pancreatitis in comparison with its expression in CP without stones (p = 0.0081). Osteopontin mRNA expression was observed in chronic calcifying pancreatitis samples but not in normal pancreas tissues. Signals corresponding to osteopontin mRNA were observed in the cytoplasm of ductal cells and macrophages. CONCLUSION: These results provide the first evidence that osteopontin may play an important role in stone formation in CP. Better understanding of the pancreatic stone formation process may lead to an effective therapeutic approach to the inhibition of pancreatic calcification associated with CP.
INTRODUCTION:Chronic pancreatitis (CP) is frequently associated with stone formation within the pancreatic duct system. The mechanism of pancreatic stone formation, however, is still unclear. AIMS: Osteopontin expression is related to urinary stone formation and several diseases associated with calcification such as atherosclerosis, breast cancer, and meningioma. We therefore hypothesized and studied whether that osteopontin may contribute to the formation of calculi in CP. METHODOLOGY: Twenty patients with CP who underwent elective surgery were included in the study. As controls, normal pancreas specimens were collected from five additional patients. We used reverse transcription polymerase chain reaction and reverse transcription in situ polymerase chain reaction to evaluate osteopontin mRNA expression and immunohistochemical staining to evaluate osteopontin-producing cells. RESULTS: No expression of osteopontin was seen in normal pancreas cells. Osteopontin expression was detected in acinar or ductal cells in all 11 cases of chronic calcifying pancreatitis, whereas in 5 of 9 CP cases without pancreatic stones there was no expression of osteopontin in acinar or ductal cells. The data revealed a high incidence of osteopontin expression in chronic calcifying pancreatitis in comparison with its expression in CP without stones (p = 0.0081). Osteopontin mRNA expression was observed in chronic calcifying pancreatitis samples but not in normal pancreas tissues. Signals corresponding to osteopontin mRNA were observed in the cytoplasm of ductal cells and macrophages. CONCLUSION: These results provide the first evidence that osteopontin may play an important role in stone formation in CP. Better understanding of the pancreatic stone formation process may lead to an effective therapeutic approach to the inhibition of pancreatic calcification associated with CP.