ag-490 and Pancreatitis

Studies have implied the positive association of JAK2/STAT3 signaling with the onset and severity of acute pancreatitis (AP). However, definitive functional study of JAK2/STAT3 signaling in the pathogenesis of acute pancreatitis in vivo is missing and its potential as a therapeutic target and the underlying mechanisms remain to be determined.. The aim of this study was to explore the role of JAK2/STAT3 signaling in the pathogenesis of hyperlipidemia-intensified caerulin-induced AP and its potential as a therapeutic target.. Using the caerulin-induced acute pancreatitis rat model, we showed that JAK2/STAT3 signaling was activated in pancreas and systemic inflammation was increased during AP. Pharmacological suppression of JAK2 by its inhibitor AG490 robustly protected against tissue damage, attenuated JAK2/STAT3 signaling and inflammatory responses. Local pancreatic tissue damage and phosphor- JAK2 in the pancreatic tissue were enhanced in animals fed with high fat diet compared to chow-diet fed animals. Interestingly, JAK2 inhibitor AG490 significantly inhibited pancreas necrosis and systemic inflammation in animals fed with high fat or chow-diet, but did not affect STAT3 signaling.. These results establish that JAK2 activation plays a significant role in the pathogenesis of caerulin-induced AP in animals on both chow and high-fat diets by regulating necrosis and systemic inflammation. Thus, our results not only clarify novel signaling mechanisms in AP but also suggest that JAK2 might constitute a target in the management of hyperlipidemia-intensified caerulin-induced AP.

Topics: Acute Disease; Animals; Ceruletide; Dietary Fats; Hyperlipidemias; Janus Kinase 2; Male; Pancreatitis; Rats; Rats, Sprague-Dawley; Signal Transduction; STAT3 Transcription Factor; Tyrphostins

NADPH oxidase is potentially associated with acute pancreatitis by producing reactive oxygen species (ROS). We investigated whether NADPH oxidase mediates the activation of Janus kinase (Jak)2/signal transducers and activators of transcription (Stat)3 and mitogen-activated protein kinases (MAPKs) to induce the expression of transforming growth factor-β1 (TGF-β1) in cerulein-stimulated pancreatic acinar cells.. AR42J cells were treated with an NADPH oxidase inhibitor diphenyleneiodonium (DPI) or a Jak2 inhibitor AG490. Other cells were transfected with antisense or sense oligonucleotides (AS or S ODNs) for NADPH oxidase subunit p22(phox) or p47(phox).. TGF-β1 was determined by enzyme-linked immonosorbent assay. STAT3-DNA binding activity was measured by electrophoretic mobility shift assay. Levels of MAPKs as well as total and phospho-specific forms of Jak1/Stat3 were assessed by Western blot analysis.. Cerulein induced increases in TGF-β1, Stat3-DNA binding activity and the activation of MAPKs in AR42J cells. AG490 suppressed these cerulein-induced changes, similar to inhibition by DPI. Cerulein-induced activation of Jak2/Stat3 and increases in MAPKs and TGF-β1 levels were inhibited in the cells transfected with AS ODN for p22(phox) and p47(phox) compared to S ODN controls.. Inhibition of NADPH oxidase may be beneficial for prevention and treatment of pancreatitis by suppressing Jak2/Stat3 and MAPKs and expression of TGF-β1 in pancreatic acinar cells.

Topics: Animals; Cell Line; Ceruletide; Enzyme Activation; Enzyme Inhibitors; Humans; Janus Kinase 2; Mitogen-Activated Protein Kinases; NADPH Oxidases; Pancreas, Exocrine; Pancreatitis; Rats; Reactive Oxygen Species; STAT3 Transcription Factor; Transforming Growth Factor beta1; Tyrphostins

Cerulein pancreatitis is similar to human edematous pancreatitis with dysregulation of the digestive enzyme production and cytoplasmic vacuolization, the death of acinar cells, edema formation, and an infiltration of inflammatory cells into the pancreas. Cytokines are up-regulated in pancreatic acinar cells stimulated with cerulein. In various cells and tissues, Janus kinase (Jak)/signal transducer and activator of transcription (Stat) pathway mediates inflammatory process. In the present study, we investigated whether the activation of Jak/Stat signaling mediates IL-1beta expression in pancreatic acinar AR42J cells stimulated with cerulein in vitro as well as the rats with cerulein pancreatitis in vivo using AG490, the Jak2 inhibitor. Activation of Jak2 and Stat3 were monitored by Western blot analysis for phosphorylated Jak2 and phosphorylated Stat3. mRNA expression and protein level of IL-1beta were determined by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbant assay (ELISA). Histological examination of pancreatic tissues were performed and serum IL-1beta levels of the rats were determined by ELISA. As a result, cerulein induced the activation of Jak2 and Stat3 as well as IL-1beta expression, which was inhibited by the treatment of AG490 in AR42J cells. In cerulein pancreatitis of the rats, edematous and inflammatory changes of the pancreas and increased serum levels of IL-1beta were suppressed by AG490 treatment. In conclusion, Jak2/Stat3 pathway may be the underlying mechanism in the pathogenesis of pancreatitis by inducing cytokines such as IL-1beta.

Topics: Animals; Cells, Cultured; Ceruletide; Disease Models, Animal; Drug Therapy, Combination; Enzyme Inhibitors; Gene Expression; Interleukin-1beta; Janus Kinase 2; Male; Pancreas; Pancreatitis; Phosphorylation; Rats; Rats, Sprague-Dawley; RNA, Messenger; STAT3 Transcription Factor; Tyrphostins