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Heme oxygenase-1 (HO-1) has an anti-inflammatory action in acute pancreatitis (AP). However, its mechanism of action and natural compounds/drugs to induce HO-1 in pancreas are not well understood. In this study, we investigated the regulatory mechanisms of HO-1 during AP using desoxo-narchinol-A (DN), the natural compound inducing HO-1 in the pancreas. Female C57/BL6 Mice were intraperitoneally injected with supramaximal concentrations of cerulein (50 μg/kg) hourly for 6 h to induce AP. DMSO or DN was administered intraperitoneally, then mice were sacrificed 6 h after the final cerulein injection. Administration of DN increased pancreatic HO-1 expression through activation of activating protein-1, mediated by mitogen-activated protein kinases. Furthermore, DN treatment reduced the pancreatic weight-to-body weight ratio as well as production of digestive enzymes and pro-inflammatory cytokines. Inhibition of HO-1 by tin protoporphyrin IX abolished the protective effects of DN on pancreatic damage. Additionally, DN treatment inhibited neutrophil infiltration into the pancreas via regulation of chemokine (C-X-C motif) ligand 2 (CXCL2) by HO-1. Our results suggest that DN is an effective inducer of HO-1 in the pancreas, and that HO-1 regulates neutrophil infiltration in AP via CXCL2 inhibition., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Inflammasomes promote the production of pro-inflammatory cytokines, such as interleukin (IL)-1β and IL-18, which are the representative mediators of inflammation. Abnormal activation of inflammasomes leads to the development of inflammatory diseases such as acute pancreatitis (AP). In this study, we demonstrate the inhibitory effects of a new natural compound fraxinellone on inflammasome formation and examine the role of inflammasomes in a mouse model of AP. AP was induced with hourly intraperitoneal injections of supramaximal concentrations of the stable cholecystokinin analogue cerulein (50 μg/kg) for 6 h. Mice were sacrificed 6 h after the final cerulein injection. Blood and pancreas samples were obtained for further experiments. Intraperitoneal injection of fraxinellone significantly inhibited the pancreatic activation of multiple inflammasome molecules such as NACHT, LRR and PYD domains-containing protein 3 (NLRP3), PY-CARD, caspase-1, IL-18, and IL-1β during AP. In addition, fraxinellone treatment inhibited pancreatic injury, elevation in serum amylase and lipase activities, and infiltration of inflammatory cells such as neutrophils and macrophages but had no effect on pancreatic edema. To investigate whether inflammasome activation leads to the infiltration of inflammatory cells, we used parthenolide, a well-known natural inhibitor, and IL-1 receptor antagonist mice. The inhibition of inflammasome activation by pharmacological/or genetic modification restricted the infiltration of inflammatory cells, but not edema, consistent with the results observed with fraxinellone. Taken together, our study highlights fraxinellone as a natural inhibitor of inflammasomes and that inflammasome inhibition may lead to the suppression of inflammatory cells during AP., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Guggulsterone (GS), a plant steroid and a compound found at high levels in Commiphora myrrha, exhibits anti-inflammatory, anti-cancer, and cholesterol-lowering effects. However, the potential of GS to ameliorate acute pancreatitis (AP) is unknown. The aim of this study was to evaluate the effects of GS on cerulein-induced AP. AP was induced by intraperitoneally injecting supramaximal concentrations of the stable cholecystokinin analog cerulein (50 μg/kg) hourly for 6 h. In the GS-treated group, GS was administered intraperitoneally (10, 25, or 50mg/kg) 1 h before the first cerulein injection. Mice were sacrificed 6 h after the final cerulein injection. Blood samples were collected to measure serum lipase levels and evaluate cytokine production. The pancreas and lung were rapidly removed for morphologic and histological examinations, flow cytometry analysis, myeloperoxidase (MPO) assay, and real-time reverse transcription-polymerase chain reaction analysis. Pre-treatment with GS attenuated cerulein-induced histological damage, reduced pancreas weight/body weight ratio, decreased serum lipase levels, inhibited infiltrations of macrophages and neutrophils, and suppressed cytokine production. Additionally, GS treatment suppressed the activation of extracellular signal-regulated protein kinase (ERK) and c-Jun N-terminal kinase (JNK) in the pancreas in cerulein-induced pancreatitis. In conclusion, our results suggest that GS attenuates AP via deactivation of ERK and JNK., (Copyright © 2015 Elsevier B.V. All rights reserved.)