NADPH OXIDASE PLAYS A KEY ROLE IN THE ACTIVATION OF PANCREATIC STELLATE CELLS

Abstract

Background: Upon activation, pancreatic stellate cells (PSCs) actively proliferate, and produce chemokines and extracellualr matrix components. Previous studies have shown that reactive oxygen species (ROS) might work as a second messenger in signal transduction, mediating PSC functions, and that antioxidants such as polyphenol curcumin inhibited the key parameters of PSC activation. A possible source of ROS in the injured pancreas is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, but the expression and possible regulation of cell functions by NADPH oxidase in PSCs remain unknown. This study aimed to clarify the roles of NADPH oxidase in the activation and cell functions of PSCs. Methods: PSC were isolated from rat pancreas tissue and used in their culture-activated, myofibroblast-like phenotype unless otherwise stated. Expression of NADPH oxidase was examined by reverse transcription-polymerase chain reaction and Western blotting. ROS formation was examined using redox-sensitive dye 2′,7′-dichlorofluorescin diacetate. We evaluated the effects of diphenylene iodonium (DPI), an inhibitor of NADPH oxidase, on the proliferation, monocyte chemoattractant protein-1 production, and expression of α-SMA and collagen genes. In addition, the effect of DPI on the spontaneous transformation of freshly-isolated cells to myofibroblast-like cells was assessed. Results: PSCs expressed key components of NADPH oxidase including p22phox and gp91phox. Growth factors and cytokines such as platelet-derived growth factor, interleukin-1β, and angiotensin II induced ROS formation, which was prevented in the presence of DPI. DPI inhibited platelet-derived growth factor-induced proliferation, interleukin-1β-induced monocyte chemoattractant protein-1 production, and expression of α-SMA and collagen genes. DPI also inhibited the spontaneous transformation to myofibroblast-like cells. Conclusion: NADPH oxidase plays a key role in the activation and cell functions of PSCs, implying a novel target for the treatment of pancreatic fibrosis.