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Activation of nuclear factor-?B in acinar cells increases the severity of pancreatitis in mice.

ABSTRACT: Nuclear factor-?B (NF-?B) is activated during early stages of pancreatitis. This transcription factor regulates genes that control many cell activities, including inflammation and survival. There is evidence that activation of NF-?B protects against pancreatitis, and, in other cases, that it promotes this disease. We compared the effects of NF-?B in different mouse models of pancreatitis to understand these complications.To model constitutive activation of NF-?B, we expressed a transgene that encodes its p65 subunit or the inhibitor of ?B kinase (IKK)2 in pancreatic acinar cells of mice. We analyzed effects on pancreatic tissues and levels of NF-?B target genes in these mice and compared them with mice that did not express transgenic p65 or IKK2 (controls).Transgenic expression of p65 led to compensatory expression of the inhibitory subunit IKB-? and, therefore, no clear phenotype. However, p65 transgenic mice given injections of cerulein, to induce acute pancreatitis, had higher levels of NF-?B activity in acinar cells, greater levels of inflammation, and more severe outcomes than control mice. In contrast, constitutive expression of IKK2 directly increased the activity of NF-?B in acinar cells and induced pancreatitis. Prolonged activity of IKK2 (3 months) resulted in activation of stellate cells, loss of acinar cells, and fibrosis, which are characteristics of chronic pancreatitis. Co-expression of IKK2 and p65 greatly increased the expression of inflammatory mediators and the severity of pancreatitis, compared with control mice.The level of NF-?B activation correlates with the severity of acute pancreatitis in mice. Longer periods of activation (3 months) lead to chronic pancreatitis. These findings indicate that strategies to inactivate NF-?B might be used to treat patients with acute or chronic pancreatitis.

SUBMITTER: Huang H

PROVIDER: S-EPMC3769090 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Activation of nuclear factor-κB in acinar cells increases the severity of pancreatitis in mice.

Huang Haojie H Liu Yan Y Daniluk Jaroslaw J Gaiser Sebastian S Chu Jun J Wang Huamin H Li Zhao-Shen ZS Logsdon Craig D CD Ji Baoan B

Gastroenterology 20121003 1

<h4>Background & aims</h4>Nuclear factor-κB (NF-κB) is activated during early stages of pancreatitis. This transcription factor regulates genes that control many cell activities, including inflammation and survival. There is evidence that activation of NF-κB protects against pancreatitis, and, in other cases, that it promotes this disease. We compared the effects of NF-κB in different mouse models of pancreatitis to understand these complications.<h4>Methods</h4>To model constitutive activation ...[more]

PMID: 23041324

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Project description:Background & aimsAcute pancreatitis is characterized by premature intracellular activation of digestive proteases within pancreatic acini and a consecutive systemic inflammatory response. We investigated how these processes interact during severe pancreatitis in mice.MethodsPancreatitis was induced in C57Bl/6 wild-type (control), cathepsin B (CTSB)-knockout, and cathepsin L-knockout mice by partial pancreatic duct ligation with supramaximal caerulein injection, or by repetitive supramaximal caerulein injections alone. Immune cells that infiltrated the pancreas were characterized by immunofluorescence detection of Ly6g, CD206, and CD68. Macrophages were isolated from bone marrow and incubated with bovine trypsinogen or isolated acinar cells; the macrophages were then transferred into pancreatitis control or cathepsin-knockout mice. Activities of proteases and nuclear factor (NF)-κB were determined using fluorogenic substrates and trypsin activity was blocked by nafamostat. Cytokine levels were measured using a cytometric bead array. We performed immunohistochemical analyses to detect trypsinogen, CD206, and CD68 in human chronic pancreatitis (n = 13) and acute necrotizing pancreatitis (n = 15) specimens.ResultsMacrophages were the predominant immune cell population that migrated into the pancreas during induction of pancreatitis in control mice. CD68-positive macrophages were found to phagocytose acinar cell components, including zymogen-containing vesicles, in pancreata from mice with pancreatitis, as well as human necrotic pancreatic tissues. Trypsinogen became activated in macrophages cultured with purified trypsinogen or co-cultured with pancreatic acini and in pancreata of mice with pancreatitis; trypsinogen activation required macrophage endocytosis and expression and activity of CTSB, and was sensitive to pH. Activation of trypsinogen in macrophages resulted in translocation of NF-kB and production of inflammatory cytokines; mice without trypsinogen activation (CTSB-knockout mice) in macrophages developed less severe pancreatitis compared with control mice. Transfer of macrophage from control mice to CTSB-knockout mice increased the severity of pancreatitis. Inhibition of trypsin activity in macrophages prevented translocation of NF-κB and production of inflammatory cytokines.ConclusionsStudying pancreatitis in mice, we found activation of digestive proteases to occur not only in acinar cells but also in macrophages that infiltrate pancreatic tissue. Activation of the proteases in macrophage occurs during endocytosis of zymogen-containing vesicles, and depends on pH and CTSB. This process involves macrophage activation via NF-κB-translocation, and contributes to systemic inflammation and severity of pancreatitis.

Project description:Disruption of iron homeostasis is associated with multiple diseases. It has been found that patients with genetic iron overload develop massive iron deposition in the pancreas. However, few studies have focused on the effect of secondary iron overload on the pancreas. The objective of the present study was to investigate the pathogenic consequences of secondary iron overload in mice. An iron overload mouse model was constructed by intraperitoneal injection of 120 mg/kg body weight of iron dextran every other week for 12 weeks. Iron deposition, immunocyte infiltration, fibrosis, oxidative stress and ferroptosis were assessed using Prussian blue staining, immunohistochemical analysis, Masson staining, Sirius red staining, RT‑qPCR analysis and western blot analysis. It was found that iron‑overloaded mice showed pancreatic iron overload, together with elevated gene expression of the iron storage factor ferritin H, and decreased expression of the iron transportation mediator divalent metal transporter 1, ferroportin 1 and transferrin receptor. Iron‑overloaded mice developed mild pancreatitis with increased serum amylase and lipase activities, as well as elevated gene expression levels of pro‑inflammatory cytokines, including interleukin (IL)‑1β, IL‑6 and inducible nitric oxide synthase. Acinar atrophy, massive immunocyte infiltration and pancreatic fibrosis were noted in the iron‑overloaded mice. As an underlying mechanism, iron‑overloaded mice showed increased pancreatic oxidative stress, with an elevated malondialdehyde level, and decreased SOD and glutathione peroxidase activity. Furthermore, iron overload led to ferroptosis with promoted expression of cytochrome c oxidase subunit II, and decreased transcripts of glutathione peroxidase 4 and solute carrier family 7 member 11. These results provided evidence that multiple intraperitoneal injections of iron dextran in mice lead to iron overload‑induced chronic pancreatitis, which suggested that secondary iron overload is a risk factor for pancreatitis and highlights the importance of iron in maintaining the normal functions of the pancreas.

Project description:The pathogenesis of pancreatitis has been linked to disruption of organelle homeostasis including macroautophagy/autophagy dysfunction and endoplasmic reticulum (ER) stress. However, the direct impact of aberrant organelle function on pancreatitis initiation and progression is largely unknown. Recently an ER membrane protein, VMP1 (vacuole membrane protein 1), has been reported to play a crucial role in autophagosome formation. Notably, we found that VMP1 is downregulated in both human chronic pancreatitis (CP) and experimental mouse acute pancreatitis (AP). Pancreatic acinar cell-specific vmp1 deletion promotes inflammation, acinar-to-ductal metaplasia, and fibrosis in mice, sharing histological similarities with human CP. Mechanistically, loss of pancreatic VMP1 leads to defective autophagic degradation and ER stress as well as activation of the NFE2L2/Nrf2 pathway. Genetic ablation of NFE2L2 attenuated pancreatitis in VMP1-deficient mice. Our data highlight the importance of VMP1 in modulating an integrated organelle stress response and its functional role in maintaining pancreas homeostasis in the context of CP.Abbreviations: AMY: amylase; ADM: acinar-to-ductal metaplasia; AP: acute pancreatitis; CASP3: caspase 3; CP: chronic pancreatitis; DDIT3/CHOP: DNA damage inducible transcript 3; DKO, double knockout; ER: endoplasmic reticulum; GCLC: glutamate-cysteine ligase catalytic subunit; GCLM: glutamate-cysteine ligase modifier subunit; HSPA5/BIP: heat shock protein family A (Hsp70) member 5; KO: knockout; KRT19/CK19: keratin 19; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MPO: myeloperoxidase; NFE2L2/NRF2: nuclear factor, erythroid 2 like 2; ND: normal donor; NQO1: NAD(P)H quinone dehydrogenase 1; PCNA: proliferating cell nuclear antigen; RIPA: radio-immunoprecipitation; SQSTM1/p62: sequestosome 1; SOX9: SRY-box transcription factor 9; TAP: trypsinogen activation peptide; TFEB: transcription factor EB; TUNEL: terminal deoxynucleotidyl transferase dUTP nick end labeling; UB: ubiquitin; VMP1: vacuole membrane protein 1; XBP1: X-box binding protein 1; YAP1, Yes1 associated transcriptional regulator; ZG: zymogen granule.

Dataset Information

Activation of nuclear factor-?B in acinar cells increases the severity of pancreatitis in mice.

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Activation of nuclear factor-κB in acinar cells increases the severity of pancreatitis in mice.

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