Overexpression of caspase-1 (interleukin-1 beta converting enzyme) in chronic pancreatitis and its participation in apoptosis and proliferation

Caspase-1, formerly designated interleukin-1 beta converting enzyme, was th e first described member of a group of cysteine proteases called caspases. It is suggested that caspases play an important role in apoptosis, but rece nt observations could show that caspase-1 might also be involved in cellula r proliferation. We investigated the expression of caspase-1 in 38 chronic pancreatitis tissues, six pancreatitis tissues from patients with pancreati c carcinoma and nine normal pancreatic tissues by immunohistochemistry. Wes tern blot analysis was used to confirm the immunohistochemical findings. We found a clear expression of caspase-1 in chronic pancreatitis, but not in normal pancreatic tissues. Interestingly, we found expression of caspase-1 in three distinct morphologic compartments: (i) in atrophic acinar cells (3 1 of 35; 89%), (ii) proliferating cells of ductal origin (33 of 38; 87%), a nd (iii) in acinar cells redifferentiating to form tubular structures (26 o f 31; 83%). These immunohistochemical findings were confirmed by Western bl ot analysis, which showed an expression of caspase-1 in 85% of the tissues. No correlation was found between any of the examined clinicopathologic fea tures and the caspase-1 expression in chronic pancreatitis. In conclusion, the expression of caspase-1 is a frequent event in chronic pancreatitis and its distribution pattern may reflect two functions of this protease: on on e hand its participation in the apoptotic pathway in atrophic acinar cells and, on the other hand, its role in proliferation and differentiation in pr oliferating duct cells.