Acinar Cell Necrosis Research Articles

Infectious pancreatic necrosis virus in Atlantic salmon, Salmo salar L., post‐smolts in the Shetland Isles, Scotland: virus identification, histopathology, immunohistochemistry and genetic comparison with Scottish mainland isolates

During mid-June 1999 peak mortalities of 11% of the total stock per week were seen at a sea cage site of Atlantic salmon, Salmo salar L., post-smolts in the Shetland Isles, Scotland. Virus was isolated on chinook salmon embryo (CHSE) cells in a standard diagnostic test and infectious pancreatic necrosis virus (IPNV) identified by enzyme-linked immunosorbent assay. IPNV was confirmed as serogroup A by a cell immunofluorescent antibody test using the cross-reactive monoclonal antibody AS-1. Four weeks after the main outbreak, virus titres in surviving moribund fish were assayed at >10(10) TCID50 g(-1) kidney. Histopathology of moribund fish was characterized by pancreatic acinar cell necrosis and a marked catarrhal enteritis of the intestinal mucosa. In the liver, necrosis, leucocytic infiltration and a generalized cell vacuolation were noted. IPNV-specific immunostaining was demonstrated in pancreas, liver, heart, gill and kidney tissue. The nucleotide sequence of the coding region of segment A was determined from the Shetland isolate. A 1180 bp fragment of the VP2 gene of this isolate was compared with a 1979 reference isolate from mainland Scottish Atlantic salmon, La/79 and another more recent mainland isolate, 432/00. Both A2 isolates were derived from carrier fish without signs of IPN and serotyped by a plaque neutralization test. The Shetland isolate shows a different nucleotide and amino acid sequence compared with the two isolates from carrier fish. These latter isolates showed identical amino acid sequences in the fragment examined, despite the 21 years separating the isolations. Sequence comparisons with other A2 (Sp) isolates on the database confirm all three Scottish isolates are A2 (Sp).

Morphological studies of graft pancreatitis following pancreas transplantation.

Morphological findings in the initial stages of graft pancreatitis were studied systematically in sequential biopsies of 16 human pancreatic allografts. In 14 patients clinical and morphological signs of graft pancreatitis developed in the early postoperative period. In all cases disturbances in the integrity of structures within acinar cells occurred during ischaemia. In ten cases activation of autophagocytosis occurred following reperfusion, with acceleration of cellular metabolism. After reperfusion a marked leucocyte reaction occurred with a later single acinar cell necrosis in six cases. At the same time, high serum pancreatic enzyme concentrations were observed in all patients following transplantation. Exocrine secretion from the allografts via the pancreatic duct was reduced, correlating with the severity of graft pancreatitis. Studies in this clinical situation might complement analyses of the cascade of morphological and pathophysiological reactions during the early stages of other types of acute pancreatitis.

Pathogenesis of Experimental Encephalomyocarditis: a Histopathological, Immunohistochemical and Virological Study in Rats

Rats (n=40) aged 8 weeks were infected, either by oronasal inoculation or by contact, with one of two different myocardial strains of encephalomyocarditis virus (EMCV), namely, the Greek strain 424/90 and the Belgian strain B279/95. The animals were killed at 11-62 days post-infection (dpi) and samples of brain, heart, pancreas, kidney, Peyer's patches, spleen, lung and thymus were processed for virological, histopathological and immunohistochemical evaluation. This experimental infection was inapparent, but virus was isolated from faeces and several organs of all animals. The main histopathological changes were focal interstitial pancreatitis, degeneration and necrosis of pancreatic acinar cells, depletion of thymus and Peyer's patches, and interstitial pneumonia. EMCV antigen was detected in the cytoplasm of cardiac muscle cells, pancreatic acinar cells and hepatic epithelial cells, and in macrophages of the spleen, lung and thymus. In the heart (the target organ of EMCV in pigs), the presence of EMCV in cardiac muscle cells without lesions lends support to the hypothesis that the rat is a natural reservoir host species of EMCV. The persistence of virus in the macrophages of the thymus may represent a mechanism of perpetuation and reactivation, under immunosuppressive conditions, of the infection.

Characterization of the acute pancreatitis induced by secretory phospholipases A 2 in rats

Acute pancreatitis (AP) is an inflammatory disease of the pancreas characterized by local inflammation and extrapancreatic effects such as lung injury. Secretory phospholipases A 2 (PLA 2s) have been implicated in triggering AP, but their exact role to evoke AP is largely unknown. Therefore, we have tested the ability of sPLA 2s to induce AP in rats, using venom sPLA 2s with residual or high enzymatic activity (bothropstoxin-II and Naja mocambique mocambique venom PLA 2, respectively), as well as sPLA 2 devoid of catalytic activity (piratoxin-I). The injection of Naja m. mocambique venom PLA 2, bothropstoxin-II or piratoxin-I (300 μg/kg each) into the common bile duct increased significantly the pancreatic plasma extravasation and myeloperoxidase activity. The lung myeloperoxidase and serum amylase were also increased for all groups, although the Naja mocambique mocambique venom PLA 2 induced higher lung myeloperoxidase and serum amylase values, compared with piratoxin-I and/or bothropstoxin-II. Histopathology of pancreas and lungs in piratoxin-I-injected rats showed interstitial oedema in both tissues, and neutrophil infiltration with acinar cell necrosis in pancreas. In conclusion, sPLA 2s induce AP in rats and the catalytic activity is not essential to induce the local effects in pancreas, although it appears to contribute partly to the remote lung injury.

EFFECTS OF BONE MARROW AND NON-BONE MARROW PAR2 ON CAERULEIN-INDUCED PANCREATITIS

Background: Global deletion of PAR2 receptors worsens the severity of pancreatitis, thus indicating that PAR2 exerts a protective effect. Aim: To determine whether that protective effect of PAR2 is afforded by PAR2 receptors expressed by bone marrow or non-bone marrow derived cells. Methods: Cell type-specific deletion of PAR2 was achieved using total body irradiation followed by selective bone marrow transplantation. PAR2+/+ and PAR2−/− mice were subjected to lethal irradiation and then rescued by administration of bone marrow obtained from either PAR2+/+ or PAR2−/− mice. Thus, the following 4 groups of animals were generated: (1) global PAR2+/+ mice; (2) global PAR2−/− mice; (3) mice with PAR2+/+ bone marrow but PAR2−/− non-bone marrow cells; and (4) mice with PAR2−/− bone marrow but PAR2+/+ non-bone marrow cells. After achieving complete bone marrow reconstitution, pancreatitis was induced by administration of 12 hourly injections of caerulein (50 μg/kg/injection). Pancreatic edema was evaluated by quantitating pancreatic water content, pancreatic inflammation by quantitating pancreatic myeloperoxidase activity, and pancreatic acinar cell injury by histologically quantitating acinar cell necrosis. Results: Pancreatic edema was increased in all animals receiving caerulein but it was further increased in animals with either global PAR2 deletion or PAR2 deletion confined to non-bone marrow derived cells. Pancreatic inflammation was also increased in all animals receiving caerulein, further increased in animals with either global PAR2 deletion or PAR2 deletion confined to bone marrow cells and even further increased by PAR2 deletion in non-bone marrow cells. Finally, acinar cell necrosis was increased in all animals receiving caerulein but it was further increased only in animals with either global PAR2 deletion or PAR2 deletion confined to non-bone marrow cells. Conclusions: Bone marrow cells contribute modestly to the protection against intrapancreatic inflammation during pancreatitis but, for the most part, protection against the edema, inflammation, and acinar cell necrosis of pancreatitis is afforded by non-bone marrow (? acinar) cells.

Calpain activation contributes to oxidative stress-induced pancreatic acinar cell injury

Oxygen radicals have been implicated as mediators in the pathogenesis of pancreatic acinar cell necrosis. However, the sequence of events between the oxidative insult and cell damage remains unclear. In the current study, we investigated whether the Ca 2+-regulated cytosolic cysteine protease calpain is activated by oxidative stress and contributes to oxidant-induced acinar cell damage. Isolated rat pancreatic acinar cells were exposed to hydrogen peroxide (H 2O 2)-generated oxidative stress in the presence or absence of the Ca 2+ chelator 1,2-bis-( o-aminophenoxy)-ethane- N, N, N′, N′-tetraacetic acid tetraacetoxymethyl ester (BAPTA-AM) and different calpain inhibitors including benzyloxycarbonyl-valyl-phenylalanine methyl ester. Calpain activation was studied by fluorescence spectrophotometry and immunoblotting. Cell injury was assessed by lactate dehydrogenase (LDH) release and characterization of the cellular ultrastructure including fluorescence-labeled actin filaments. Exposure of acinar cells to H 2O 2 provoked a time- and dose-dependent increase in calpain proteolytic activity involving the ubiquitous isoforms μ- and m-calpain. The activation of calpain reflected the time course of developing cytotoxicity as demonstrated by increased LDH release. Inhibition of oxidant-induced calpain activity by BAPTA-AM and various calpain inhibitors provoked a decline in oxidant-induced cell injury. In particular, changes in the actin filament organization characterized by an increase in the basolateral actin and by a detachment of actin from the cell membrane in the region of membrane blebs were clearly reduced. In summary, our findings suggest that acinar cell damage through oxidative stress requires activation of calpain and that the actin cytoskeleton belongs to the cellular targets of the protease. The results support the hypothesis that calpain activation may play a role in the development of acute pancreatitis.

Epidemiology, Pathology, and Immunohistochemistry of Layer Hens Naturally Affected with H5N1 Highly Pathogenic Avian Influenza in Japan

Epidemiology, pathology, and immunohistochemistry were investigated in layer hens affected with H5N1 highly pathogenic avian influenza, which occurred for the first time in 79 years in Japan. The farm, which had a total of 34,640 chickens, experienced up to 43.3% mortality before the chickens were depopulated. Clinically, the affected chickens exhibited mortality without apparent clinical signs. Histologically, hepatocytic necrosis; necrosis of ellipsoids and follicles with fibrin in the spleen; necrosis with glial nodules in the brain stem, cerebrum, and cerebellum; necrosis of acinar cells in the pancreas; and necrosis of lymphoid tissues in intestinal lamina propria were seen. Occasionally, mild bronchiolitis, degeneration of smooth muscle fibers in the cecum, and mild tubulonephrosis were noted. Immunohistochemically, influenza virus antigens were detected often in the liver and spleen, heart, intestine, gizzard, proventriculus, and oviduct. In addition, antigens were seen also in the brain, kidney, pancreas, and ovary, but seldom in the lung and trachea. Virus antigen was mainly detected in the capillary endothelium and parenchymal cells. This suggests that virus excretion from the respiratory tract was not as prevalent as that from the digestive tract in the present cases.

Effect of endothelin-1 receptor antagonists on histological and ultrastructural changes in the pancreas and trypsinogen activation in the early course of caerulein-induced acute pancreatitis in rats

To assess the effect of non-selective ET(A/B) (LU 302872) and selective ET(A) (LU 302146) antagonist on pancreatic histology and ultrastructure of acinar cells in connection with trypsinogen activation in early caerulein-induced AP. Male Wistar rats with caerulein-induced AP, lasting 4 h, were treated i.p. with 10 and 20 mg/kg b.w. of each antagonist. Edema, inflammatory infiltration, necrosis and vacuolization of acinar cells in the pancreas were scored at 0-3 scale. Free active trypsin (FAT), total potential trypsin (TPT) after activation with enterokinase, and index of trypsinogen activation (%FAT/TPT) were assayed in pancreatic homogenates. In untreated AP, the edema, inflammatory infiltration, necrosis and vacuolization increased as compared to control healthy rats (P<0.01). None of the treatment exerted any meaningful effect on the edema and inflammatory infiltration. The selective antagonist increased slightly the necrosis score to 0.82+/-0.06 at higher dose (P<0.05) vs 0.58+/-0.06 in untreated AP. The non-selective antagonist increased slightly the vacuolization score to 2.41+/-0.07 at higher dose (P<0.01) vs 1.88+/-0.08 in untreated AP. The decrease in the number of zymogen granules, disorganization of endoplasmic reticulum, autophagosomes and cytoplasmic vacuoles were more prominent in treated AP than in untreated AP groups. %FAT/TPT in untreated AP increased about four times (18.4+/-3.8 vs 4.8+/-1.3 in control group without AP, P<0.001). Treatment of AP with both antagonists did not affect significantly augmented trypsinogen activation. The treatment with endothelin-1 receptors (non-selective ET(A/B) and selective ET(A)) antagonists has essential effect neither on the edema and inflammatory infiltration nor on trypsinogen activation observed in the early course of caerulein-induced AP. Nevertheless a slight increase of the necrosis and vacuolization score and some of the ultrastructural data could suggest the possibility of their undesired effects in caerulein-induced AP at investigated doses.

DECREASED NEUTROPHIL INFILTRATION IN THE PANCREAS AND LUNGS OF HSP70 TRANSGENIC MICE DURING CAERULEIN-INDUCED PANCREATITIS.

Exposure of organisms to initial sub-lethal stress leads to synthesis of heat shock proteins (HSPs). These stress proteins confer protection against subsequent severe stress. HSP70 is a well-studied member of stress proteins. We have shown earlier that overexpression of this protein by thermal and nonthermal stress is protective in pancreatitis and associated lung injury. Induction of thermal and non-thermal stress can modulate a number of other events in the tissue; therefore, studies using transgenic animals are necessary to delineate the role of this important stress protein in reduction of pancreatitis. After the initial injury in the tissue, neutrophil infiltration contributes significantly to the development of pancreatitis and associated lung injury. In the present study, we have evaluated neutrophil sequestration and tissue injury in HSP70 transgenic mice during careulein induced pancreatitis. Methods: Transgenic mice with human HSP70 were generated using a construct containing HSP70 under the control of CMV promoter. Pancreatitis was induced in wild type and transgenic mice by administration of caerulein (50 μg/kg/hourly for 12 hours). Pancreas and lungs were collected from wild type and transgenic animals and neutrophil sequestration was studied by measuring myeloperoxidase activity and histological alterations and tissue injury were quantitated by morphometry. Results: There was significantly less neutrophil infiltration both in the pancreas (control 3.5±2.1; wild type 540.5±94.5; HSP-transgenic 105.4±26.1) and lungs (control 338.14±133.4; wild type 1530.1±284.9; HSP-transgenic 808.9±226.7) of the HSP70-transgenic mice as compared to wild type animals following caerulein administration. Further, intra-acinar vacuolization, acinar cell necrosis and interstitial edema were reduced in the transgenic animals in comparison to wild type mice. Conclusion: These results suggest that HSP70 overexpression has a protective role in pancreatitis and can play a critical role in reducing the associated lung injury.

ROLE OF TOLL-LIKE RECEPTORS (TLR4) IN CAERULEIN INDUCED PANCREATITIS.

TLR’s (toll-like receptors) play an important role in activating innate immune response to pathogen-related molecules hence also known as pattern recognition receptors (PRR’s). It is expressed on monocytes, neutrophils and macrophages. It binds to LPS and is identified as a type I transmembrane protein with extracellular domains containing leucine-rich repeats that may participate in ligand recognition. Acute pancreatitis is characterized by rapid production and release of inflammatory cytokines, which play a major role in the local pancreatic and systemic complications of the disease. The purpose of this study was to determine whether pathologic progression of acute pancreatitis is altered in the absence of TLR4 receptors. Method: Acute pancreatitis was induced by administering 12 hourly i.p. injections of caerulein (50 μg/kg) in Wild type and TLR4 knockout mice. Control mice received normal saline injections. Mice were sacrificed one hour after the last injection. The severity of pancreatitis was determined by measuring serum amylase activity, pancreatic water content, and sequestration of neutrophils (quantitated by myeloperoxidase activity) in the pancreatic tissue and by histological assessment of acinar cell injury. Results: Administration of caerulein for 12 hours resulted in pancreatic edema, hyperamylasemia, increased pancreatic MPO activity and pancreatic acinar cell necrosis in wild type mice. In contrast, caerulein administration to TLR4 knockout mice resulted in significantly less severe pancreatitis. Serum amylase was reduced more than 1.6 fold in TLR4 −/ − as compared to wild type mice. Pancreatic water content was reduced from 83.3±0.4 in wild type to 79.5±0.4 in TLR4 −/ − mice (p ≤ 0.05) after 12 caerulein i.p. injections. MPO activity in the pancreas after caerulein administration was significantly reduced from 363.3±58.5 in wild type to 88.0±9.7 in TLR4 −/ − mice (p ≤ 0.05). Similarly acinar cell necrosis was reduced to 6.8±0.9 as compared to 17.3±1.5 in wild type mice (p ≤ 0.05). Conclusions: These results demonstrate that the severity of acute pancreatitis is ameliorated in the mice in which TLR4 receptor has been genetically deleted. Furthermore, these results suggest that TLR4 play a significant pro-inflammatory role in the progression of acute pancreatitis.

EPIDURAL ANESTHESIA RESTORES PANCREATIC MICROCIRCULATION AND DECREASES THE SEVERITY OF ACUTE PANCREATITIS.

Background and Aims: A decrease in pancreatic microcirculatory blood flow has been involved in the severity of acute pancreatitis. Because epidural anesthesia increases intestinal blood flow, we postulated that epidural anesthesia with bupivacaine might improve the pancreatic hypoperfusion induced by acute pancreatitis and concomitantly decrease the severity of the disease. Methods: In rats injected with taurocholic acid in the biliopancreatic duct, we measured the pancreatic microcirculatory blood flow (laser Doppler flowmetry) and the severity of the disease (amylasemia, metabolic acidosis, and acinar cell necrosis on histologic studies), in the presence or in the absence of epidural anesthesia. Results: Epidural anesthesia with bupivacaine, which had no effect in healthy rats, improved the pancreatic hypoperfusion induced by acute pancreatitis with a concomitant decrease in the severity of metabolic acidosis and a diminished tissue injury. Conclusions: Epidural anesthesia should therefore be considered as a new treatment to prevent the conversion of edematous to necrotizing acute pancreatitis.

Apoptosis of pancreatic acinar cells in acute pancreatitis: is it good or bad?

Acute pancreatitis is a disease of variable severity in which some patients experience mild, self-limited attacks while others manifest a severe, highly morbid, and frequently lethal attack. The events that regulate the severity of acute pancreatitis are, for the most part, unknown. Several recent studies have suggested that the acinar cell response to injury may be an important determinant of disease severity. In these studies, mild acute pancreatitis was found to be associated with extensive apoptotic acinar cell death while severe acute pancreatitis was found to involve extensive acinar cell necrosis but very little acinar cell apoptosis. These observations have led to the hypothesis that apoptosis might be a favorable response to acinar cell and that interventions which favor induction of apoptotic, as opposed to necrotic, acinar cell death might reduce the severity of an attack of acute pancreatitis. This review aims to discuss our current understanding of the contribution of acinar cell apoptosis to the severity of acute pancreatitis.

Apoptosis versus necrosis in acute pancreatitis.

Acute pancreatitis is a disease of variable severity in which some patients experience mild, self-limited attacks, whereas others manifest a severe, highly morbid, and frequently lethal attack. The events that regulate the severity of acute pancreatitis are, for the most part, unknown. It is generally believed that the earliest events in acute pancreatitis occur within acinar cells and result in acinar cell injury. Other processes, such as recruitment of inflammatory cells and generation of inflammatory mediators, are believed to occur subsequent to acinar cell injury, and these "downstream" events are believed to influence the severity of the disease. Several recently reported studies, however, have suggested that the acinar cell response to injury may, itself, be an important determinant of disease severity. In these studies, mild acute pancreatitis was found to be associated with extensive apoptotic acinar cell death, whereas severe acute pancreatitis was found to involve extensive acinar cell necrosis but very little acinar cell apoptosis. These observations led to the hypothesis that apoptosis could be a favorable response to acinar cells and that interventions that favor induction of apoptotic, as opposed to necrotic, acinar cell death might reduce the severity of an attack of acute pancreatitis. Indeed, in an experimental setting, the induction of pancreatic acinar cell apoptosis protects mice against acute pancreatitis. Little is known about the mechanism of apoptosis in the pancreatic acinar cell, although some early attempts have been made in that direction. Also, clinical relevance of these experimental studies remains to be investigated.

L-arginine-induced experimental pancreatitis.

Despite medical treatment, the lethality of severe acute pancreatitis is still high (20-30%). Therefore, it is very important to find good animal models to characterise the events of this severe disease. In 1984, Mizunuma et al. developed a new type of experimental necrotizing pancreatitis by intraperitoneal administration of a high dose of L-arginine in rats. This non-invasive model is highly reproducible and produces selective, dose-dependent acinar cell necrosis. Not only is this a good model to study the pathomechanisms of acute necrotizing pancreatitis, but it is also excellent to observe and influence the time course changes of the disease. By writing this review we illuminate some new aspects of cell physiology and pathology of acute necrotizing pancreatitis. Unfortunately, the reviews about acute experimental pancreatitis usually did not discuss this model. Therefore, the aim of this manuscript was to summarise the observations and address some challenges for the future in L-arginine-induced pancreatitis.

Estrogen prevention of lacrimal gland cell death and lymphocytic infiltration

Previous studies have shown that ovariectomy causes necrosis of lacrimal acinar cells, apoptosis of plasma cells and gland lymphocytic infiltration. Both, lacrimal gland cell death and lymphocytic infiltration were prevented by androgen treatment. Since estrogens are removed by ovariectomy, and the synthetic estrogen diethylstilbestrol has been shown to affect some biochemical correlates of lacrimal secretion, the purpose of this study was to determine the effect of 17-β-estradiol treatment on ovariectomy-induced cell death and lymphocytic infiltration. Sexually mature female New Zealand white rabbits (4–4·5 kg) were ovariectomized and divided into two groups. One group was treated with 0·5 mg kg −1 per day 17-β-estradiol, and the other group with vehicle alone. A third group of sham operated rabbits was used as controls and they also were treated with vehicle alone. Six days after surgery, the animals were euthanized, the lacrimal glands removed and processed for analysis of apoptosis as assessed by DNA fragmentation, and for morphological examination. DNA fragmentation was determined using the TUNEL assay and agarose gel electrophoresis. Sections were also stained for rabbit thymic lymphocyte antigen (RTLA), and rabbit CD18. Labelled nuclei and stained areas were quantified by automated densitometry. Ovariectomized rabbits showed a significant increase in the values for degraded DNA as a percent of total nuclear area (2·90±0·40%) compared to sham operated rabbits (0·73±0·22%). 17-β-estradiol treatment in ovariectomized rabbits prevented the increase in DNA degradation. Examination of TUNEL assay at higher magnification (40×) confirmed previous studies showing that ovariectomy caused apoptosis of interstitial cells. Significant numbers of bulging cells of very pale appearance under light microscopy, also confirm previously identified necrotic cells in acinar regions. Treatment with 17-β-estradiol prevented this necrosis. Increased numbers of RTLA + and CD18 + interstitial cells were also evident after ovariectomy. 17-β-estradiol treatment prevented the increase in the number of lymphoid cells. We confirmed previous observations that suggest that glandular atrophy observed after ovariectomy is likely to proceed by necrosis of acinar cells rather than apoptosis, and that ovariectomy triggers an inflammatory response in the gland. These results suggest that in addition to androgens, estrogens also seem to play a role to maintain lacrimal gland structure and function. A decrease in available estrogen levels could trigger both lacrimal gland apoptosis and necrosis, as well as lymphocytic infiltration. Although, the effect of estrogens in these experiments seems to be direct and not through androgens, the possibility of the role of an autocrine and/or paracrine factors, promoted by estrogen on lacrimal gland cells still needs to be investigated.

Pathogenesis of Encephalomyocarditis Virus (EMCV) Infection in Piglets during the Viraemia Phase: a Histopathological, Immunohistochemical and Virological Study

Six piglets aged 20 days were inoculated oranasally with 5 ml of a suspension (10 6 TCID 50/ml) of a Greek myocardial strain of encephalomyocarditis virus (EMCV). The animals either died ( n=2) or were killed for examination on days 1,2 or 3 post-inoculation (pi). EMCV was isolated from virtually all organs examined (heart, tonsils, palatine glands, pancreas, spleen, small intestine and mesenteric lymph nodes). Histopathologically, interstitial myocarditis, necrosis of cardiac muscle cells and Purkinje fibres, and necrotizing tonsillitis were detected in all inoculated piglets. Focal interstitial pancreatitis, necrosis of pancreatic acinar cells and Langerhans islet cells, and necrosis of germinal centre lymphocytes of the lymph nodes and Peyer's patches were detected in two piglets that died or were killed on day 3 pi. Immunohistochemically, viral antigen was detected in epithelial cells of all organs examined, including the tonsils, palatine glands, pancreatic interlobular ducts and small intestine. This suggests that EMCV is epitheliotropic, in addition to its known myocardial tropism. The frequent presence of intracytoplasmic EMCV in macrophages of the tonsils and spleen supports the hypothesis that macrophages play a role in viral replication and dissemination in the body.

Role of Macrophage Inflammatory Peptide-2 in Cerulein-Induced Acute Pancreatitis and Pancreatitis-Associated Lung Injury

Acute pancreatitis is an inflammatory process of variable severity, and leukocytes are thought to play a key role in the development of pancreatitis and pancreatitis-associated lung injury. The effects of mediators released by these inflammatory cells may induce tissue damage. The aim of our study was to evaluate the role of the chemokine, macrophage inflammatory protein-2 (MIP-2), in the pathogenesis of cerulein-induced pancreatitis and pancreatitis-associated lung injury. The severity of pancreatitis was measured by serum amylase, pancreatic edema, acinar cell necrosis, and myeloperoxidase activity. Lung injury was quantitated by evaluating lung microvascular permeability and lung myeloperoxidase activity. To determine the role of MIP-2 in the pathophysiology of the disease, anti-MIP-2 antibody was administered either 1 hour before or 2 hours after the start of cerulein administration. MIP-2 concentrations increased in serum, pancreas, and lung tissues in mice treated with cerulein. Anti-MIP-2 antibody administrated either before or after cerulein partially protected against pancreas and lung injury. These results show that MIP-2 plays a key role in the pathophysiology of acute pancreatitis and that MIP-2 blockade may improve the outcome of the disease.

Effect of IS-741 on ethionine-induced acute pancreatitis in rats: relation to pancreatic acinar cell regeneration.

Tissue destruction arising from neutrophil infiltration of the pancreas and other organs in acute pancreatitis is supposed to be suppressed by IS-741. We studied the effect of IS-741 on acute pancreatitis induced by DL-ethionine in rats. Rats fed with a low protein diet for 11 days received daily intraperitoneal administration of DL-ethionine (20 mg/100 g) for the last 4 days of the diet. To evaluate the therapeutic effect on ethionine-induced pancreatitis, IS-741 (10 mg/kg s.c.) was administered every 8 h beginning after the second ethionine injection (IS group). An equal volume of saline was used for control rats as alternative to IS-741 (control group). The rats were killed 1, 3, 5, and 7 days after the last injection of ethionine. Blood was collected to measure concentrations of the inflammatory cytokine, interleukin-8. Histologic and biochemical examinations of the pancreas were performed. The pancreatic weight, DNA content, and protein levels were determined. The pancreas was histologically examined. Pancreatic tissue in the control group showed marked infiltration of inflammatory cells, and acinar cell necrosis was widespread 1 day after the last injection of ethionine (day 1). The severity of acute pancreatitis was alleviated in rats treated with IS-741 (IS group). Pancreatic wet weight and DNA content in the IS group were higher than those in the control group on day 1. Pancreatic protein level per DNA in the IS group was higher than that in the control group on day 7. The plasma interleukin-8 level in the control group was higher than that in the IS group on day 5. Therapeutic administration of IS-741 ameliorated ethionine-induced acute pancreatitis in rats, and IS-741 could be a useful drug to treat patients with severe acute pancreatitis.

Severe acute pancreatitis and reduced acinar cell apoptosis in the exocrine pancreas of mice deficient for the Cx32 gene

Background & Aims: The early events leading to acinar cell injury during acute pancreatitis are poorly characterized. Signaling through gap junction channels contributes to the homeostasis of the exocrine pancreas by coordinating acinar cell activity within an acinus. To explore the role of gap junctional communication in acinar cell response to injury, we analyzed the course of acute pancreatitis induced by injection of cerulein in mice deficient for Cx32, the major gap junction protein expressed in the exocrine pancreas. Methods: The severity of pancreatitis was evidenced by measuring serum amylase activity, pancreatic edema, acinar cell necrosis, pancreatic tumor necrosis factor α concentration, and myeloperoxidase activity. Acinar cell apoptosis was detected by terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling (TUNEL), caspase-3 activity, and Bax/Bcl-2 expression. Expression and function of connexin were evaluated by immunofluorescence and dye coupling. Results: Cx32-deficient mice exhibited a deleterious course of acute pancreatitis with increased necrosis, edema, and inflammation of the exocrine pancreas. In addition, the exocrine pancreas of Cx32-deficient mice showed a decreased number of TUNEL-positive acinar cells and decreased caspase-3 activity but no change in Bax or Bcl-2 pancreatic expression. Interestingly, chemicals known to induce apoptosis in vivo had no effect on Cx32-deficient pancreatic acinar cells. Conclusions: Deficiency of a pancreatic connexin converts a mild reversible form of acute pancreatitis into a severe disease and decreases the sensitivity of acinar cells to apoptotic stimuli. The results show that acinar cell-to-cell communication plays a key role in the modulation of severity of acute pancreatitis.

Subacute necrotizing sialadenitis in the buccal mucosa

J Oral Maxillofac Surg 60:1494-1496, 2002