Lutein inhibits IL­6 expression by inducing PPAR­Î³ activation and SOCS3 expression in cerulein­stimulated pancreatic acinar cells.

Acute pancreatitis is a severe inflammatory disease of the pancreas. In experimental acute pancreatitis, cerulein induces the expression of interleukin­6 (IL­6) by activating Janus kinase (JAK) 2/signal transducer and activator of transcription (STAT) 3 in pancreatic acinar cells. Ligands of peroxisome proliferator activated receptor­Î³ (PPAR­Î³) and suppressor of cytokine signaling (SOCS) 3 inhibit IL­6 expression by suppressing JAK2/STAT3 in cerulein­stimulated pancreatic acinar AR42J cells. Lutein, an oxygenated carotenoid, upregulates and activates PPAR­Î³ to regulate inflammation in a renal injury model. The present study aimed to determine whether lutein activated PPAR­Î³ and induced SOCS3 expression in unstimulated AR42J cells, and whether lutein inhibited activation of JAK2/STAT3 and IL­6 expression via activation of PPAR­Î³ and SOCS3 expression in cerulein­stimulated AR42J cells. The anti­inflammatory mechanism of lutein was determined using reverse transcription­quantitative PCR, western blot analysis and enzyme­linked immunosorbent assay in AR42J cells stimulated with or without cerulein. In another experiment, cells were treated with lutein and the PPAR­Î³ antagonist GW9662 or the PPAR­Î³ agonist troglitazone prior to cerulein stimulation to determine the involvement of PPAR­Î³ activation. The results indicated that lutein increased PPAR­Î³ and SOCS3 levels in unstimulated cells. Cerulein increased phospho­specific forms of JAK2 and STAT3, and mRNA and protein expression of IL­6, but decreased SOCS3 levels in AR42J cells. Cerulein­induced alterations were suppressed by lutein or troglitazone. GW9662 alleviated the inhibitory effect of lutein on JAK2/STAT3 activation and IL­6 expression in cerulein­stimulated cells. In conclusion, lutein inhibited the activation of JAK2/STAT3 and reduced IL­6 levels via PPAR­Î³­mediated SOCS3 expression in pancreatic acinar cells stimulated with cerulein.

Docosahexaenoic Acid Inhibits Cytokine Expression by Reducing Reactive Oxygen Species in Pancreatic Stellate Cells.

Pancreatic stellate cells (PSCs) are activated by inflammatory stimuli, such as TNF-α or viral infection. Activated PSCs play a crucial role in the development of chronic pancreatitis. Polyinosinic-polycytidylic acid (poly (I:C)) is structurally similar to double-stranded RNA and mimics viral infection. Docosahexaenoic acid (DHA) exhibits anti-inflammatory activity. It inhibited fibrotic mediators and reduced NF-κB activity in the pancreas of mice with chronic pancreatitis. The present study aimed to investigate whether DHA could suppress cytokine expression in PSCs isolated from rats. Cells were pre-treated with DHA or the antioxidant N-acetylcysteine (NAC) and stimulated with TNF-α or poly (I:C). Treatment with TNF-α or poly (I:C) increased the expression of monocyte chemoattractant protein 1 (MCP-1) and chemokine C-X3-C motif ligand 1 (CX3CL1), which are known chemoattractants, and enhanced intracellular and mitochondrial reactive oxygen species (ROS) production and NF-κB activity, but reduced mitochondrial membrane potential (MMP). Increased intracellular and mitochondrial ROS accumulation, cytokine expression, MMP disruption, and NF-κB activation were all prevented by DHA in TNF-α- or poly (I:C)-treated PSCs. NAC suppressed TNF-α- or poly (I:C)-induced expression of MCP-1 and CX3CL1. In conclusion, DHA inhibits poly (I:C)- or TNF-α-induced cytokine expression and NF-κB activation by reducing intracellular and mitochondrial ROS in PSCs. Consumption of DHA-rich foods may be beneficial in preventing chronic pancreatitis by inhibiting cytokine expression in PSCs.

HSP90beta interacts with Rac1 to activate NADPH oxidase in Helicobacter pylori-infected gastric epithelial cells.

Reactive oxygen species (ROS) are involved in the pathogenesis of Helicobacter pylori (H. pylori)-induced gastric disorders including inflammation. NADPH oxidase has been considered as a major source of ROS in phagocytic and non-phagocytic cells. Small G protein Rac1 is one components of NADPH oxidase complex. Heat shock protein 90 kDa (HSP90) modulates cytokine production in H. pylori-infected gastric epithelial cells. The present study aims to investigate the relation of HSP90beta and Rac1 on the activation of NADPH oxidase in H. pylori-infected gastric epithelial cells. As a result, H. pylori-induced translocation of HSP90beta from the cytosol to the membrane and activated Rac1 in gastric epithelial AGS cells. HSP90beta physically interacted with Rac1, which resulted in the activation of NADPH oxidase in H. pylori-infected AGS cells. Down-regulation of HSP90beta by transfection of HSP90beta siRNA suppressed the activation of Rac1, activity of NADPH oxidase and the production of H(2)O(2) in H. pylori-infected AGS cells. In conclusion, H. pylori induces the translocation of HSP90beta from the cytosol to the membrane and interaction of HSP90beta and Rac1, which leads to the activation of NADPH oxidase and production of ROS in gastric epithelial cells. HSP90beta may be the target molecule for treatment of H. pylori-induced gastric injury.