Loss of Ifnar1 in Pancreatic Acinar Cells Ameliorates the Disease Course of Acute Pancreatitis

Type I interferon constitutes an essential component of the combinational therapy against viral disease. Acute pancreatitis is one side effect of type I interferon-based therapy, implying that activation of type I interferon signaling affects the homeostasis and integrity of pancreatic acinar cells. Here, we investigated the role of type I interferon signaling in pancreatic acinar cells using a caerulein-induced murine model of acute pancreatitis. Pancreas-specific ablation of interferon (alpha and beta) receptor 1 (Ifnar1) partially protected animals from caerulein-induced pancreatitis, as demonstrated by reduced tissue damage. Profiling of infiltrating immune cells revealed that this dampened tissue damage response correlated with the number of macrophages in the pancreas. Pharmacologic depletion of macrophages reversed the protective effect of Ifnar1 deficiency. Furthermore, expression of chemokine (C-C motif) ligand 2 (Ccl2), a potent factor for macrophage recruitment, was significantly increased in the Ifnar1-deficient pancreas. Thus, type I interferon signaling in pancreatic acinar cells controls pancreatic homeostasis by affecting the macrophage-mediated inflammatory response in the pancreas.     

Effects of gabexate mesilate on serum inflammatory cytokines in rats with acute necrotizing pancreatitis

Gabexate mesilate is a synthetic protease inhibitor. The effectiveness of gabexate mesilate in patients with acute pancreatitis is controversial. Proinflammatory cytokines are associated with systemic inflammatory response syndrome (SIRS) in acute pancreatitis. A compensatory anti-inflammatory response occurs in parallel with SIRS. We investigated the effects of gabexate mesilate on acute necrotizing pancreatitis in rats, emphasizing the changes in serum levels of proinflammatory and anti-inflammatory cytokines. Acute necrotizing pancreatitis was induced by retrograde infusion of sodium taurodeoxycholate into the pancreatobiliary duct in rats. The rats were divided into three groups. Group I was given gabexate mesilate 2 mg/kg/h i.v. continuously 1 h before the induction of acute pancreatitis. Group II was given gabexate mesilate the same dose immediately after the induction of acute pancreatitis. Group III was given normal saline as the controls. Serum levels of amylase, lipase, tumor necrosis factor alpha, interleukin-6, and interleukin-10, pancreatic histopathology and hemodynamics were examined at 5h after the induction of acute pancreatitis. Gabexate mesilate significantly reduced serum levels of amylase, lipase, tumor necrosis factor alpha and interleukin-6 at 5 h. Serum levels of interleukin-10 significantly increased in Group I, as compared with Groups II and III. The severity of pancreatic histopathology, the reduction of mean arterial pressure, the volume of ascites and pancreatic wet weight/body weight ratios were also significantly improved by the administration of gabexate mesilate. The beneficial effects of gabexate mesilate on acute pancreatitis may be, in part, due to the modulation of inflammatory cytokine responses.     

Pancreatitis-associated protein I suppresses NF-kappa B activation through a JAK/STAT-mediated mechanism in epithelial cells

Pancreatitis-associated protein I (PAP I), also known as HIP, p23, or Reg2 protein, has recently been implicated in the endogenous regulation of inflammation. Although it was initially characterized as a protein that is overexpressed in acute pancreatitis, PAP I has also been associated with a number of inflammatory diseases, such as Crohn's disease. Knowing that PAP I and IL-10 responses share several features, we have used a pancreatic acinar cell line (AR42J) to assess the extent to which their expression is reciprocally regulated, and whether the JAK/STAT and NF-kappaB signaling pathways are involved in the suppression of inflammation mediated by PAP I. We observed that PAP I is induced in epithelial cells by IL-10 and by PAP I itself. In contrast, we found phosphorylation and nuclear translocation of STAT3 and induction of suppressor of cytokine signaling 3 in response to PAP I exposure. Finally, a JAK-specific inhibitor, tyrphostin AG490, markedly prevented PAP I-induced NF-kappaB inhibition, pointing to a cross-talk between JAK/STAT3 and NF-kappaB signaling pathways. Together, these findings indicate that PAP I inhibits the inflammatory response by blocking NF-kappaB activation through a STAT3-dependent mechanism. Important functional similarities to the anti-inflammatory cytokine IL-10 suggest that PAP I could play a role similar to that of IL-10 in epithelial cells.     

The role of mitogen-activated protein kinase phosphatase-1 in the response of alveolar macrophages to lipopolysaccharide: attenuation of proinflammatory cytokine biosynthesis via feedback control of p38

Mitogen-activated protein (MAP) kinases are critical mediators of innate immune responses. In response to lipopolysaccharide (LPS), MAP kinases are rapidly activated and play an important role in the production of proinflammatory cytokines. Although a number of MAP kinase phosphatases (MKPs) have been identified, their roles in the control of cytokine production have not been well defined. In the present report, we investigated the role of MKP-1 in alveolar macrophages stimulated with LPS. We found that LPS triggered transient activation of three MAP kinase subfamilies, ERK, JNK, and p38, in both immortalized and primary murine alveolar macrophages. MKP-1 was rapidly induced by LPS, and its induction correlated with the dephosphorylation of these MAP kinases. Blocking MKP-1 with triptolide prolonged the activities of both JNK and p38 in immortalized alveolar macrophages. Stimulation of primary alveolar macrophages isolated from MKP-1-deficient mice with LPS resulted in a prolonged p38 phosphorylation compared with wild type alveolar macrophages. Accordingly, these MKP-1-deficient alveolar macrophages also mounted a more robust and rapid tumor necrosis factor alpha production than their wild type counterparts. Adenovirus-mediated MKP-1 overexpression significantly attenuated tumor necrosis factor alpha production in immortalized alveolar macrophages. Finally, MKP-1 was induced by a group of corticosteroids frequently prescribed for the treatment of inflammatory lung diseases, and the anti-inflammatory potencies of these drugs closely correlated with their abilities to induce MKP-1. Our studies indicated that MKP-1 plays an important role in dampening the inflammatory responses of alveolar macrophages. We speculate that MKP-1 may represent a novel target for therapeutic intervention of inflammatory lung diseases.     

p8 gene is necessary for tumor establishment

We identified a new gene, called p8, which showed a strong induction during the acute phase of pancreatitis. Further experiments have shown that p8 mRNA is activated in response to several stresses and that its activation is not restricted to pancreatic cells. p8 is a nuclear protein and biochemical and biophysical studies showed that p8 was in many structural aspects very similar to the HMG (high mobility group) proteins, although sharing with them low amino acid sequence homology. Also, p8 was found overexpressed in many human cancers. Therefore, we wondered whether the p8-mediated response to cellular stress was necessary for tumor establishment. Subcutaneous or intraperitoneal injections of transformed p8-expressing fibroblasts led to tumor formation in nude mice, but no tumor was observed with transformed p8-deficient cells. Restoring p8 expression in transformed p8-deficient fibroblasts led to tumor formation demonstrating that p8 expression is necessary for tumor development and suggesting that the stress-response mechanisms governed by p8 are required for tumor establishment.     

电针联合ICE抑制剂在急性胰腺炎的治疗中的作用及机制

观察和探讨电针联合白细胞介素(IL-1β)转化酶(ICE)抑制剂对炎症介质抑制和诱导急性胰腺炎腺泡细胞凋亡的作用。选取90只SD大鼠随机分为对照组、模型组和干预组,每组30只。各组造模后在第6小时、第12小时和第24小时各时间点分别检测10只大鼠。抑制剂组于造模前48 h采用电针并开始腹腔注射ICE抑制剂2.5 mg/100 mg体质量,间隔12 h注射1次。胰腺炎组仅在相同时间注射同等量的生理盐水。应用细胞凋亡原位标记(TUNEL)染色、ELISA方法等,检测血清中淀粉酶、肿瘤坏死因子-α(TNF-α)、IL-1β和胰腺细胞凋亡。HE染色见胰腺组织中典型的细胞核固缩及凋亡小体形成。干预组各个时间点病理学评分和血淀粉酶、TNF-α、IL-1β浓度均低于胰腺炎组,胰腺细胞凋亡指数高于胰腺炎组(p<0.05)。电针联合ICE抑制剂能减轻急性胰腺炎严重程度,其机制可能与其对炎症介质的抑制和诱导胰腺细胞的凋亡有关。     

Necro-inflammatory response of pancreatic acinar cells in the pathogenesis of acute alcoholic pancreatitis

The role of pancreatic acinar cells in initiating necro-inflammatory responses during the early onset of alcoholic acute pancreatitis (AP) has not been fully evaluated. We investigated the ability of acinar cells to generate pro- and anti-inflammatory mediators, including inflammasome-associated IL-18/caspase-1, and evaluated acinar cell necrosis in an animal model of AP and human samples. Rats were fed either an ethanol-containing or control diet for 14 weeks and killed 3 or 24 h after a single lipopolysaccharide (LPS) injection. Inflammasome components and necro-inflammation were evaluated in acinar cells by immunofluorescence (IF), histology, and biochemical approaches. Alcohol exposure enhanced acinar cell-specific production of TNFα, IL-6, MCP-1 and IL-10, as early as 3 h after LPS, whereas IL-18 and caspase-1 were evident 24 h later. Alcohol enhanced LPS-induced TNFα expression, whereas blockade of LPS signaling diminished TNFα production in vitro, indicating that the response of pancreatic acinar cells to LPS is similar to that of immune cells. Similar results were observed from acinar cells in samples from patients with acute/recurrent pancreatitis. Although morphologic examination of sub-clinical AP showed no visible signs of necrosis, early loss of pancreatic HMGB1 and increased systemic levels of HMGB1 and LDH were observed, indicating that this strong systemic inflammatory response is associated with little pancreatic necrosis. These results suggest that TLR-4-positive acinar cells respond to LPS by activating the inflammasome and producing pro- and anti-inflammatory mediators during the development of mild, sub-clinical AP, and that these effects are exacerbated by alcohol injury.     

Messenger RNA sequence and expression of rat pancreatitis-associated protein, a lectin-related protein overexpressed during acute experimental pancreatitis.

Rat pancreatitis-associated protein (PAP) is an additional protein appearing in pancreatic juice after induction of prancreatic inflammation. Its messenger RNA was cloned and sequenced from pancreas. The deduced amino acid sequence revealed that PAP was synthetized as a preprotein with, in its mature form, a predicted molecular weight of 16,630. A search in protein data bases revealed a marked homology with the carbohydrate binding region of animal lectins; no hemagglutination activity could be shown for PAP, but the protein induced extensive bacterial aggregation. In healthy rats, the very low level of PAP expression in pancreas could be increased up to 4-fold by physiological stimuli such as chronic hormonal or cholinergic stimulation of pancreatic secretion and adaptation of rats to a carbohydrate-rich diet. By contrast, induction of acute experimental pancreatitis by retrograde injection of sodium taurocholate resulted in dramatic overexpression. Pancreatic concentration of PAP mRNA increased more than 300 x within 12 h whereas concentrations of mRNAs encoding major secretory proteins such as amylase decreased. PAP overexpression persisted during the 2 days of the acute phase and then returned to the control level during pancreatic recovery. PAP mRNA could not be evidenced in liver, stomach, salivary glands, brain, kidney, or testis. Its pattern of expression during severe pancreatic aggression suggests that it might be a stress protein involved in the control of bacterial proliferation.     

The naïve effector cells of collagen type I during acute experimental pancreatitis are acinar cells and not pancreatic stellate cells

Objective

The purpose of this study was to investigate the expression of collagen type I and the mRNA level of its regulatory factor, TGF-β1, in tissue samples of acute pancreatitis and to determine the significance of collagen type I in predisposition to pancreatic fibrosis during acute pancreatitis.

Methods

Sprague–Dawley rats were divided into an experimental group (30 rats) and a control group (12 rats). The rats in the experimental group were intraperitoneally injected with cerulein to induce acute pancreatitis. The distribution and expression of collagen type I in the pancreatic tissues were examined by immunohistochemical staining. The mRNA level of TGF-β1 was determined by real-time polymerase chain reaction (PCR).

Results

(1) Collagen type I was localized in the cytoplasm of pancreatic acinar cells. With pancreatitis progressed, strong positive staining for collagen type I covered whole pancreatic lobules, whereas, the islet tissue, interlobular area, and pancreatic necrotic area were negative for collagen type I. (2) The level of TGF-β1 mRNA in rats from the experimental group increased gradually the establishment of acute pancreatitis, and was significantly higher than that in the control group at every time point.

Conclusions

(1) During acute pancreatitis, pancreatic acinar cells, not pancreatic stellate cells as traditionally believed, were the naïve effector cells of collagen type I. (2) TGF-β1 played a key role in regulating collagen I expression during acute pancreatitis.     

Pancreatic acinar cells-derived cyclophilin A promotes pancreatic damage by activating NF-κB pathway in experimental pancreatitis

Inflammation triggered by necrotic acinar cells contributes to the pathophysiology of acute pancreatitis (AP), but its precise mechanism remains unclear. Recent studies have shown that Cyclophilin A (CypA) released from necrotic cells is involved in the pathogenesis of several inflammatory diseases. We therefore investigated the role of CypA in experimental AP induced by administration of sodium taurocholate (STC). CypA was markedly upregulated and widely expressed in disrupted acinar cells, infiltrated inflammatory cells, and tubular complexes. In vitro, it was released from damaged acinar cells by cholecystokinin (CCK) induction. rCypA (recombinant CypA) aggravated CCK-induced acinar cell necrosis, promoted nuclear factor (NF)-κB p65 activation, and increased cytokine production. In conclusion, CypA promotes pancreatic damage by upregulating expression of inflammatory cytokines of acinar cells via the NF-κB pathway.     

Progression or resolution of coxsackievirus B4-induced pancreatitis: a genomic analysis

Group B coxsackieviruses are associated with chronic inflammatory diseases of the pancreas, heart, and central nervous system. Chronic pancreatitis, which can develop from acute pancreatitis, is considered a premalignant disorder because it is a major risk factor for pancreatic cancer. To explore the genetic events underlying the progression of acute to chronic disease, a comparative analysis of global gene expression during coxsackievirus B4-induced acute and chronic pancreatitis was undertaken. A key feature of acute pancreatitis that resolved was tissue regeneration, which was accompanied by increased expression of genes involved in cell growth, inhibition of apoptosis, and embryogenesis and by increased division of acinar cells. Acute pancreatitis that progressed to chronic pancreatitis was characterized by lack of tissue repair, and the expression map highlighted genes involved in apoptosis, acinoductular metaplasia, remodeling of the extracellular matrix, and fibrosis. Furthermore, immune responses appeared skewed toward development of alternatively activated (M2) macrophages and T helper 2 (Th2) cells during disease that resolved and toward classically activated (M1) macrophages and Th1 cells during disease that progressed. Our hypothesis is that growth and differentiation signals coupled with the M2/Th2 milieu favor acinar cell proliferation, while diminished growth signals and the M1/Th1 milieu favor apoptosis of acinar cells and remodeling/proliferation of the extracellular matrix, resulting in fibrosis.     

Expression of human cationic trypsinogen (PRSS1) in murine acinar cells promotes pancreatitis and apoptotic cell death

Hereditary pancreatitis (HP) is an autosomal dominant disease that displays the features of both acute and chronic pancreatitis. Mutations in human cationic trypsinogen (PRSS1) are associated with HP and have provided some insight into the pathogenesis of pancreatitis, but mechanisms responsible for the initiation of pancreatitis have not been elucidated and the role of apoptosis and necrosis has been much debated. However, it has been generally accepted that trypsinogen, prematurely activated within the pancreatic acinar cell, has a major role in the initiation process. Functional studies of HP have been limited by the absence of an experimental system that authentically mimics disease development. We therefore developed a novel transgenic murine model system using wild-type (WT) human PRSS1 or two HP-associated mutants (R122H and N29I) to determine whether expression of human cationic trypsinogen in murine acinar cells promotes pancreatitis. The rat elastase promoter was used to target transgene expression to pancreatic acinar cells in three transgenic strains that were generated: Tg(Ela-PRSS1)NV, Tg(Ela-PRSS1*R122H)NV and Tg(Ela-PRSS1*N29I)NV. Mice were analysed histologically, immunohistochemically and biochemically. We found that transgene expression is restricted to pancreatic acinar cells and transgenic PRSS1 proteins are targeted to the pancreatic secretory pathway. Animals from all transgenic strains developed pancreatitis characterised by acinar cell vacuolisation, inflammatory infiltrates and fibrosis. Transgenic animals also developed more severe pancreatitis upon treatment with low-dose cerulein than controls, displaying significantly higher scores for oedema, inflammation and overall histopathology. Expression of PRSS1, WT or mutant, in acinar cells increased apoptosis in pancreatic tissues and isolated acinar cells. Moreover, studies of isolated acinar cells demonstrated that transgene expression promotes apoptosis rather than necrosis. We therefore conclude that expression of WT or mutant human PRSS1 in murine acinar cells induces apoptosis and is sufficient to promote spontaneous pancreatitis, which is enhanced in response to cellular insult.     

Substance P treatment stimulates chemokine synthesis in pancreatic acinar cells via the activation of NF-kappaB

Acinar cell injury early in acute pancreatitis leads to a local inflammatory reaction and to the subsequent systemic inflammatory response, which may result in multiple organ dysfunction and death. Inflammatory mediators, including chemokines and substance P (SP), are known to play a crucial role in the pathogenesis of acute pancreatitis. It has been shown that pancreatic acinar cells produce the chemokine monocyte chemoattractant protein-1 (MCP-1) in response to caerulein hyperstimulation, demonstrating that acinar-derived MCP-1 is an early mediator of inflammation in acute pancreatitis. Similarly, SP levels in the pancreas and pancreatic acinar cell expression of neurokinin-1 receptor, the primary receptor for SP, are both increased during secretagogue-induced experimental pancreatitis. This study aims to examine the functional consequences of exposing mouse pancreatic acinar cells to SP and to determine whether it leads to proinflammatory signaling, such as production of chemokines. Exposure of mouse pancreatic acini to SP significantly increased synthesis of MCP-1, macrophage inflammatory protein-1alpha (MIP-1alpha), as well as MIP-2. Furthermore, SP also increased NF-kappaB activation. The stimulatory effect of SP was specific to chemokine synthesis through the NF-kappaB pathway, since the increase in chemokine production was completely attenuated when pancreatic acini were pretreated with the selective NF-kappaB inhibitor NF-kappaB essential modulator-binding domain peptide. This study shows that SP-induced chemokine synthesis in mouse pancreatic acinar cells is NF-kappaB dependent.     

Pancreatitis-associated protein 2 modulates inflammatory responses in macrophages

Pancreatitis-associated proteins (PAP) are stress-induced secretory proteins that are implicated in immunoregulation. Previous studies have demonstrated that PAP is up-regulated in acute pancreatitis and that gene knockdown of PAP correlated with worsening severity of pancreatitis, suggesting a protective effect for PAP. In the present study, we investigated the effect of PAP2 in the regulation of macrophage physiology. rPAP2 administration to clonal (NR8383) and primary macrophages were followed by an assessment of cell morphology, inflammatory cytokine expression, and studies of cell-signaling pathways. NR8383 macrophages which were cultured in the presence of PAP2 aggregated and exhibited increased expression of IL-1, IL-6, TNF-alpha, and IL-10; no significant change was observed in IL-12, IL-15, and IL-18 when compared with controls. Chemical inhibition of the NFkappaB pathway abolished cytokine production and PAP facilitated nuclear translocation of NF-kappaB and phosphorylation of IkappaB alpha inhibitory protein suggesting that PAP2 signaling involves this pathway. Cytokine responses were dose dependent. Interestingly, similar findings were observed with primary macrophages derived from lung, peritoneum, and blood but not spleen. Furthermore, PAP2 activity was inhibited by the presence of serum, inhibition which was overcome with increased PAP2. Our results demonstrate a new function for PAP2: it stimulates macrophage activity and likely modulates the inflammatory environment of pancreatitis.