Effect Of Celecoxib On The Inflammatory Injury Of Pancreatic Acinar Cells In Rat

Background: Acute pancreatitis (AP) is a commonly-occurred severe disease with high morbidity and mortality. The disease involves a complicated cascade of events, which start in the pancreatic acinar cells and result in injury of acinar cells and local and systemic inflammation. Cyclooxygenase-2(COX-2) and nuclear factor-kappaB(NF-κB) play very important roles in the pathogenesis of acute pancreatitis. The expression of COX-2 is up-regulated by proinflammatory factors, such as IL-1, TNF-αand NF-κB, and inhibited by anti-inflammatory factors, such as IL-10, TGF-βet al, which reduce the of severity of pancreatic injury. It shows that NF-κB plays essential roles in the initiation and progression of AP and the activation of NF-κB leads to over-expression of COX-2. Some studies have revealed that selective inhibitor of COX-2, such as celecoxib, is a potential agent in the treatment of experimental acute pancreatitis, but the molecular mechanisms of selective inhibitors of COX-2 still remain unclear. In this study, we use the isolated pancreatic acinar cells, excluding influences of neuro-humor factors in vivo, to investigate the benefical effect of celecoxib on the cerulein-stimulated inflammation in pancreatic acinar cells and also to study the relationship between COX-2 and NF-κB.Objective: In this study, the expressions of COX-2 and NF-κB were observed in pancreatic acinar cells of rat, which were stimulated by cerulein. The effect of celecoxib, an selective inhibitor of COX-2, on the expression of NF-κB was examined, so as to investigate the relationship between COX-2 and NF-κB in pancreatic acinar cells,as well as the favorable effect of celecoxib on inflammatory injury of pancreatic acinar cells.Methods: pancreatic acinar cells were isolated by collagenase digestion from male SD rats, and were divided into control, cerulean-stimulated and celecoxib-pretreated groups. Cerulein groups were given with CCK analog cerulean. The final cerulean concentration was 10-7 M. Celecoxib-pretreated groups were treated with celecoxib of final concentration 100μM, 15 minutes before incubating with crerulein. Cells were incubated for 1, 3, 6 and 12 hours respectively. Cell viability was determined by typan blue dyeing, amylase and LDH activity were measured using amylase and LDH assay kit. The expressions of COX-2 mRNA and NF-κB mRNA were evaluated by RT-PCR. And the protein expressions of COX-2 and NF-κB p65 in pancreatic acinar cells were detected by immunocytochemistry.Results: 1) Compared with control group, cell viability of cerulein group was significant decreased at different time point (P<0.05). Secretion rates of amylase and LDH, as well as expressions of COX-2 and NF-κB mRNA, were significant elevated at different time point (P<0.05). The expressions of COX-2 and NF-κB protein increased in cell. 2) Compared with cerulein group, cell viability of celecoxib group was improved (P<0.05) and secretion rates of amylase and LDH were significant decreased at different time point (P<0.05). The expressions of COX-2 and NF-κB have no significant difference. 3) There was a positive correlation between COX-2 and NF-κB (P<0.01).Conclusion: COX-2 and NF-κB were activated at early time and play important roles in the inflammation of pancreatic acinar cells and these two factors had a positive correlation. Celecoxib could inhibit the activity of COX-2 and down-regulate the expression of COX-2, but could not inhibit NF-κB. Celecoxib could be beneficial to the relief of inflammatory injury of pancreatic acinar cells stimulated by cerulein.