Suppression of cerulein-induced cytokine expression by antioxidants in pancreatic acinar cells

Reactive oxygen species (ROS) has been considered to be an important regulator in the development and pathogenesis of pancreatitis and an activator of the transcription factor, nuclear factor-κB (NF-κB), regulating inflammatory cytokine gene expression. NF-κB activation was demonstrated in cerulein pancreatitis, which rapidly induces an acute, edematous form of pancreatitis. This study aimed to investigate whether cerulein induced ROS generation, lipid peroxide and hydrogen peroxide production, NF-κB activation, and expression of cytokines (IL-1β, IL-6) in pancreatic acinar cells. An additional aim was to establish whether these alterations were inhibited by antioxidants such as glutathione, superoxide dismutase, and catalase and an inhibitor of NF-κB activation, pyrrolidine dithiocarbamate (PDTC). To determine the possible interactions of the antioxidants and PDTC with cerulein-induced signaling, Ca²⁺ signal and amylase release were monitored in the pancreatic acinar cells treated with cerulein in the presence or absence of either the antioxidants or PDTC. The results showed that cerulein generated ROS and increased lipid peroxide and hydrogen peroxide production in the acinar cells, as determined by dichlorofluorescein diacetate dye. This resulted in NF-κB activation and the induction of cytokine gene expression in the cells. The cerulein-induced NF-κB activation was in parallel to IκBα degradation. Cerulein also induced Ca²⁺ signals and amylase release in acinar cells. Both antioxidants (glutathione, superoxide dismutase, catalase) and PDTC inhibited the cerulein-induced, oxidant-mediated alterations but did not affect the cerulein-evoked Ca²⁺ signals and amylase release in acinar cells. In conclusion, ROS, generated by cerulein, activates NF-κB, resulting in the up-regulation of inflammatory cytokine gene expression in acinar cells. NF-κB inhibition by scavenging ROS might alleviate the inflammatory response in pancreatic acinar cells by suppressing cytokine gene expression.