Peritoneal inflammatory cells in acute pancreatitis: Relationship of infiltration dynamics and cytokine production with severity of illness

Deletion of myeloid-specific Orai1 calcium channel does not affect pancreatic tissue damage in experimental acute pancreatitis

BACKGROUND

Store-operated Ca2+ entry (SOCE) mediated by ORAI1 channel plays a crucial role in acute pancreatitis (AP). Macrophage is an important regulator in amplifying pancreatic tissue damage, but little is known about the role of ORAI1 in macrophages. In this study, we examined the effects of macrophage-specific ORAI1 on pancreatic tissue damage in AP.

METHOD

Myeloid-specific Orai1 deficient mice was generated by crossing a LysM-Cre mouse line with Orai1f/f mice. Bone marrow-derived macrophages (BMDMs) were isolated, cultured, and stimulated to induce M1 or M2 macrophage polarization. Intracellular Ca2+ signals were measured by time-lapse confocal microscope imaging, with a Ca2+ indicator (Fluo 4). Experimental AP was induced by hourly intraperitoneal injections of caerulein or retrograde biliopancreatic infusion of sodium taurocholate. Pancreatic tissue damage was assessed by histopathological scoring and immunostaining. Sepsis was induced by intraperitoneal injection of lipopolysaccharide; organ damage and serum pro-inflammatory cytokines were measured.

RESULT

Myeloid-specific Orai1 deletion exhibited minimal effect on SOCE in M0 macrophages and promoted M2 macrophage polarization ex vivo. Myeloid-specific Orai1 deletion did not affect pancreatic tissue damage, nor neutrophil or macrophage infiltration in two models of AP. Similarly, myeloid-specific Orai1 deletion did not influence overall survival rate in a model of sepsis, nor lung, kidney, and liver damage; while serum pro-inflammatory cytokines, including IL-6, TNF-α, and IL-1β were higher in Orai1ΔLysM mice, but were largely reduced in mice with Orai1 inhibitor.

CONCLUSION

Our data suggest that ORAI1 may not be a predominant SOCE channel in macrophages and play a limited role in mediating pancreatic tissue damage in AP.

Neutrophil-specific ORAI1 Calcium Channel Inhibition Reduces Pancreatitis-associated Acute Lung Injury

Acute pancreatitis is initiated within pancreatic exocrine cells and sustained by dysregulated systemic inflammatory responses mediated by neutrophils. Store-operated Ca2+ entry (SOCE) through ORAI1 channels in pancreatic acinar cells triggers acute pancreatitis, and ORAI1 inhibitors ameliorate experimental acute pancreatitis, but the role of ORAI1 in pancreatitis-associated acute lung injury has not been determined. Here, we showed mice with pancreas-specific deletion of Orai1 (Orai1ΔPdx1, ∼70% reduction in the expression of Orai1) are protected against pancreatic tissue damage and immune cell infiltration, but not pancreatitis-associated acute lung injury, suggesting the involvement of unknown cells that may cause such injury through SOCE via ORAI1. Genetic (Orai1ΔMRP8) or pharmacological inhibition of ORAI1 in murine and human neutrophils decreased Ca2+ influx and impaired chemotaxis, reactive oxygen species production, and neutrophil extracellular trap formation. Unlike pancreas-specific Orai1 deletion, mice with neutrophil-specific deletion of Orai1 (Orai1ΔMRP8) were protected against pancreatitis- and sepsis-associated lung cytokine release and injury, but not pancreatic injury in experimental acute pancreatitis. These results define critical differences between contributions from different cell types to either pancreatic or systemic organ injury in acute pancreatitis. Our findings suggest that any therapy for acute pancreatitis that targets multiple rather than single cell types is more likely to be effective.

Ascites in Acute Pancreatitis: Clinical Implications and Management

Clinically significant ascites in acute pancreatitis (AP) is rarely encountered and is a result of multifactorial pathogenesis. Early reactionary ascites in AP usually does not require any treatment and resolves spontaneously in majority of patients. A diagnostic analysis should be performed in case of ascites developing in the latter stages with increasing pain or worsening organ failure. Low serum albumin-ascites gradient ascites with amylase > 1000 U/l is highly suggestive of pancreatic ascites that is usually associated with duct disruption. A combination of nasojejunal feeding, subcutaneous octreotide, endoscopic drainage and rarely, surgery are employed in managing this difficult to treat condition. There is a need of further studies to better understand the clinical role of ascites as well as contribution of other factors like hypoalbuminemia and portal hypertension to its development in AP.

ANGPTL4 exacerbates pancreatitis by augmenting acinar cell injury through upregulation of C5a

Pancreatitis is the inflammation of the pancreas. However, little is known about the genes associated with pancreatitis severity. Our microarray analysis of pancreatic tissues from mild and severe acute pancreatitis mice models identified angiopoietin-like 4 (ANGPTL4) as one of the most significantly upregulated genes. Clinically, ANGPTL4 expression was also increased in the serum and pancreatic tissues of pancreatitis patients. The deficiency in ANGPTL4 in mice, either by gene deletion or neutralizing antibody, mitigated pancreatitis-associated pathological outcomes. Conversely, exogenous ANGPTL4 exacerbated pancreatic injury with elevated cytokine levels and apoptotic cell death. High ANGPTL4 enhanced macrophage activation and infiltration into the pancreas, which increased complement component 5a (C5a) level through PI3K/AKT signaling. The activation of the C5a receptor led to hypercytokinemia that accelerated acinar cell damage and furthered pancreatitis. Indeed, C5a neutralizing antibody decreased inflammatory response in LPS-activated macrophages and alleviated pancreatitis severity. In agreement, there was a significant positive correlation between C5a and ANGPTL4 levels in pancreatitis patients. Taken together, our study suggests that targeting ANGPTL4 is a potential strategy for the treatment of pancreatitis.

Exosomes and pancreatic diseases: status, challenges, and hopes

Pancreatic disease, including pathologies such as acute pancreatitis (AP), chronic pancreatitis (CP), and pancreatic cancer (PC), is a complicated and dangerous clinical condition involving the disruption of exocrine or endocrine function. PC has one of the highest mortality rates among cancers due to insufficient diagnosis in early stages. Furthermore, efficient treatment options for the disease etiologies of AP and CP are lacking. Thus, the identification of new therapeutic targets and reliable biomarkers is required. As essential couriers in intercellular communication, exosomes have recently been confirmed to play an important role in pancreatic disease, but the specific underlying mechanisms are unknown. Herein, we summarize the current knowledge of exosomes in pancreatic disease with respect to diagnosis, molecular mechanisms, and treatment, proposing new ideas for the study of pancreatic disease.

Involvement of exosomes in lung inflammation associated with experimental acute pancreatitis

A frequent complication of acute pancreatitis is the lung damage associated with the systemic inflammatory response. Although various pro-inflammatory mediators generated at both local and systemic levels have been identified, the pathogenic mechanisms of the disease are still poorly understood. In recent years, exosomes have emerged as a new intercellular communication system able to transfer encapsulated proteins and small RNAs and protect them from degradation. Using an experimental model of taurocholate-induced acute pancreatitis in rats, we aimed to evaluate the role of exosomes in the extent of the systemic inflammatory response. Induction of pancreatitis increased the concentration of circulating exosomes, which showed a different proteomic profile to those obtained from control animals. A series of tracking experiments using PKH26-stained exosomes revealed that circulating exosomes effectively reached the alveolar compartment and were internalized by macrophages. In vitro experiments revealed that exosomes obtained under inflammatory conditions activate and polarize these alveolar macrophages towards a pro-inflammatory phenotype. Interestingly, the proteomic analysis of circulating exosomes during acute pancreatitis suggested a multi-organ origin with a relevant role for the liver as a source of these vesicles. Tracking experiments also revealed that the liver retains the majority of exosomes from the peritoneal cavity. We conclude that exosomes are involved in the lung damage associated with experimental acute pancreatitis and could be relevant mediators in the systemic effects of pancreatitis. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Mechanisms of interleukin-22’s beneficial effects in acute pancreatitis

Acute pancreatitis (AP) is a disorder characterized by parenchymal injury of the pancreas controlled by immune cell-mediated inflammation. AP remains a significant challenge in the clinic due to a lack of specific and effective treatment. Knowledge of the complex mechanisms that regulate the inflammatory response in AP is needed for the development of new approaches to treatment, since immune cell-derived inflammatory cytokines have been recognized to play critical roles in the pathogenesis of the disease. Recent studies have shown that interleukin (IL)-22, a cytokine secreted by leukocytes, when applied in the severe animal models of AP, protects against the inflammation-mediated acinar injury. In contrast, in a mild AP model, endogenous IL-22 has been found to be a predominantly anti-inflammatory mediator that inhibits inflammatory cell infiltration via the induction of Reg3 proteins in acinar cells, but does not protect against acinar injury in the early stage of AP. However, constitutively over-expressed IL-22 can prevent the initial acinar injury caused by excessive autophagy through the induction of the anti-autophagic proteins Bcl-2 and Bcl-X_L. Thus IL-22 plays different roles in AP depending on the severity of the AP model. This review focuses on these recently reported findings for the purpose of better understanding IL-22’s regulatory roles in AP which could help to develop a novel therapeutic strategy.

Role of macrophages in the progression of acute pancreatitis

In addition to pancreatic cells, other inflammatory cell populations contribute to the generation of inflammatory mediators during acute pancreatitis. In particular, macrophages could be activated by mediators released during pancreatitis by a damaged pancreas. It has been reported that peritoneal macrophages, alveolar macrophages and Kupffer cells become activated in different stages of severe acute pancreatitis. However, macrophages display remarkable plasticity and can change their physiology in response to environmental cues. Depending on their microenvironmental stimulation, macrophages could follow different activation pathways resulting in marked phenotypic heterogeneity. This ability has made these cells interesting therapeutical targets and several approaches have been assayed to modulate the progression of inflammatory response secondary to acute pancreatitis. However, despite the recent advances in the modulation of macrophage function in vivo, the therapeutical applications of these strategies require a better understanding of the regulation of gene expression in these cells.

Essential role of monocytes and macrophages in the progression of acute pancreatitis

Acute pancreatitis (AP) is an inflammatory condition of the pancreas caused by an imbalance in factors involved in maintaining cellular homeostasis. Earliest events in AP occur within acinar cells accompanied by other principal contributors to the inflammatory response i.e. the endothelial cells, immunocytes (granulocytes, monocytes/macrophages, lymphocytes) and neutrophils. Monocytes/macrophages are important inflammatory mediators, involved in the pathophysiology of AP, known to reside in the peritoneal cavity (in the vicinity of the pancreas) and in peripancreatic tissue. Recent studies suggested that impaired clearance of injured acini by macrophages is associated with an altered cytokine reaction which may constitute a basis for progression of AP. This review focuses on the role of monocytes/macrophages in progression of AP and discusses findings on the inflammatory process involved.

CO2 abdominal insufflation decreases local and systemic inflammatory response in experimental acute pancreatitis

OBJECTIVES

Acute pancreatitis (AP) is a serious disease that is amplified by an associated systemic inflammatory response. We investigated the effect of CO2 pneumoperitoneum on the local and systemic inflammatory response in AP.

METHODS

Acute pancreatitis was induced in Wistar rats by 5% taurocholate intraductal injection. Carbon dioxide pneumoperitoneum was applied for 30 minutes before the induction of AP. Inflammatory parameters were evaluated in the peritoneum (ascites, cell number, and tumor necrosis factor alpha [TNF-alpha]), serum (amylase, TNF-alpha, interleukin-6 [IL-6], and IL-10), pancreas (myeloperoxidase [MPO] activity, cyclo-oxygenase 2 and inducible nitric oxide synthase expression, and histological diagnosis), liver, and lung (mitochondria dysfunction and MPO activity).

RESULTS

Abdominal insufflation with CO2 before induction of AP caused a significant decrease in ascites volume, cells, and TNF-alpha in the peritoneal cavity and in serum TNF-alpha and IL-6 but not IL-10 levels. In the pancreas, this treatment reduced MPO activity, acinar and fat necrosis, and the expression of inducible nitric oxide synthase and cyclo-oxygenase 2. There were no significant differences on serum amylase levels, liver mitochondrial function, and pulmonary MPO between groups.

CONCLUSIONS

Our data demonstrated that CO2 pneumoperitoneum reduced pancreatic inflammation and attenuated systemic inflammatory response in AP. This article suggests that CO2 pneumoperitoneum plays a critical role on the better outcome in patients undergoing laparoscopic pancreatic surgery.

Clinical effects of laparotomy with perioperative continuous peritoneal lavage and postoperative hemofiltration in patients with severe acute pancreatitis

Background

The elevated serum and peritoneal cytokine concentrations responsible for the systemic response syndrome (SIRS) and multiorgan failure in patients with severe acute pancreatitis lead to high morbidity and mortality rates. Prompted by reports underlining the importance of reducing circulating inflammatory mediators in severe acute pancreatitis, we designed this study to evaluate the efficiency of laparotomy followed by continuous perioperative peritoneal lavage combined with postoperative continuous venovenous diahemofiltration (CVVDH) in managing critically ill patients refractory to intensive care therapy. As the major clinical outcome variables we measured morbidity, mortality and changes in the Acute Physiology and Chronic Health Evaluation (APACHE II) score and cytokine concentrations in serum and peritoneal lavage fluid over time.

Methods

From a consecutive group of 23 patients hospitalized for acute pancreatitis, we studied 6 patients all with Apache II scores ≥19, who underwent emergency surgery for acute complications (5 for an abdominal compartment syndrome and 1 for septic shock) followed by continuous perioperative peritoneal lavage and postoperative CVVDH. CVVDH was started within 12 hours after surgery and maintained for at least 72 hours, until the multiorgan dysfunction syndrome improved. Samples were collected from serum, peritoneal lavage fluid and CVVDH dialysate for cytokine assay. Apache II scores were measured daily and their association with cytokine levels was assessed.

Results

All six patients tolerated CVVDH well, and the procedure lasted a mean 6 days (range, 3-12). Five patients survived and one died of Acinetobacter infection after surgery (mortality rate 16.6%). The mean APACHE II score was ≥ 19 (range 19-22) before laparotomy and decreased significantly during peritoneal lavage and postoperative CVVDH (P = 0.013 by matched-pairs Students t-test). The decrease in cytokine concentrations in serum and lavage fluid was associated with the decrease in APACHE II scores and high interleukin 6 (IL-6) and tumor necrosis factor (TNF) concentrations in the hemofiltrate.

Conclusion

In critically ill patients with abdominal compartment syndrome, septic shock or high APACHE II scores related to severe acute pancreatitis, combining emergency laparotomy with continuous perioperative peritoneal lavage followed by postoperative CVVHD effectively reduces the local and systemic cytokines responsible for multiorgan dysfunction syndrome thus improving patients' outcome.

Intervention of pyrrolidine dithiocarbamate and tetrandrine on cellular calcium overload of pancreatic acinar cells induced by serum and ascitic fluid from rats with acute pancreatitis

BACKGROUND AND AIM

To investigate the effects of serum and ascitic fluid from rats with acute pancreatitis (AP) on cellular free calcium concentration ([Ca(2+)]i) of isolated rat pancreatic acinar cells, and the intervention of pyrrolidine dithiocarbamate (PDTC) and tetrandrine (Tet) to cellular calcium overload in AP.

METHODS

AP was induced in Sprague-Dawley rats with a retrograde pancreatic duct injection of 3% sodium deoxycholate, and confirmed by histopathological examination and amylase activity assay. The rat serum and ascitic fluid were collected at 1, 5 and 10 h after AP induction, and used as irritants on isolated rat pancreatic acinar cells. The effects on intracellular [Ca(2+)]i, and cell viability were examined. Then, the antagonistic effects of different concentrations of PDTC and Tet were assessed.

RESULTS

The irritation with AP serum and ascitic fluid reduced the survival rate of the isolated rat pancreatic acinar cells and increased the cellular [Ca(2+)]i significantly (P < 0.05). As AP induction course prolonged, the stimulation effect of the AP serum and ascitic fluid intensified. In the pretreated acinar cells with PDTC or Tet, the decreased cell vitality reverted. The elevation of [Ca(2+)]i in the acinar cells significantly ameliorated (significant, P < 0.05; very significant, P < 0.01).

CONCLUSION

The serum and ascitic fluid from AP rats drastically elevate the [Ca(2+)]i in isolated pancreatic acinar cells and decrease cell vitality, while the pretreatment of cells with PDTC and Tet offsets the calcium overload irritated by the AP serum and ascitic fluid and protects these isolated acinar cells.

Pharmacokinetic and pharmacodynamic properties of biapenem, a carbapenem antibiotic, in rat experimental model of severe acute pancreatitis

OBJECTIVES

It is known that prophylaxis with imipenem reduces the risk of infection accompanying severe acute pancreatitis. In this study,we modified a rat experimental model of severe acute pancreatitis for antibiotic evaluation, and the effect of biapenem was compared with that of imipenem to determine the usefulness of biapenem.

METHODS

Severe acute pancreatitis was induced by 5% sodium taurocholate. Antibiotics were subcutaneously administered at 3 and 6 hours and evaluated at 12 hours after the pancreatitis induction. For pharmacokinetic evaluation, antibiotics were subcutaneously administered at 3 hours after the pancreatitis induction.

RESULTS

From 3 hours after the induction, bacteria were detected from the pancreas. The total bacterial count increased in a time-dependent manner for 12 hours. Biapenem administration reduced the total bacterial count in the pancreas, as observed in imipenem administration. The plasma concentration of biapenem was almost equivalent to that of imipenem; however, the pancreatic penetration of biapenem was approximately twice that of imipenem in this model.

CONCLUSIONS

Biapenem was suggested to be effective in prophylactic treatment of infectious complications as much as imipenem because of its superior penetration to the pancreas in severe acute pancreatitis.

The pathogenic mechanism of severe acute pancreatitis complicated with renal injury: a review of current knowledge

The onset of severe acute pancreatitis (SAP) is clinically harmful as it may rapidly progress from a local pancreatic inflammation into proemial systemic inflammatory reactions. Patients with SAP have a high mortality, with most cases of death resulting from complications involving the failure of organs other than the pancreas. The distinctive feature of SAP is that once it starts, it may aggrevate the clinical condition of the patient continuously, so that the levels of injury to the other organs surpass the severity of the pancreatic lesion, even causing multiple organ failure and, ultimately, death. In clinical practice, the main complications in terms of organ dysfunctions are shock, acute respiratory failure, acute renal failure, among others. The acute renal injury caused by SAP is not only able to aggravate the state of pancreatitis, but it also develops into renal failure and elevates patients' mortality. Studies have found that the injury due to massive inflammatory mediators, microcirculation changes and apoptosis, among others, may play important roles in the pathogenic mechanism of acute renal injury.

Study progress on mechanism of severe acute pancreatitis complicated with hepatic injury

Study on the action mechanism of inflammatory mediators generated by the severe acute pancreatitis (SAP) in multiple organ injury is a hotspot in the surgical field. In clinical practice, the main complicated organ dysfunctions are shock, respiratory failure, renal failure, encephalopathy, with the rate of hepatic diseases being closely next to them. The hepatic injury caused by SAP cannot only aggravate the state of pancreatitis, but also develop into hepatic failure and cause patient death. Its complicated pathogenic mechanism is an obstacle in clinical treatment. Among many pathogenic factors, the changes of vasoactive substances, participation of inflammatory mediators as well as OFR (oxygen free radical), endotoxin, etc. may play important roles in its progression.

Efeito da hipertermia na pancreatite aguda grave experimental

OBJETIVO: O objetivo deste estudo é avaliar os efeitos da hipertermia na pancreatite aguda (PA) grave experimental induzida por ácido taurocólico. MÉTODO: A PA grave foi induzida pela injeção retrógrada de ácido taurocólico a 2,5% ou 5% no ducto pancreático principal. Após a indução, os animais foram colocados numa gaiola contendo duas lâmpadas de 100 W. A temperatura corporal foi aumentada para 39,5ºC e mantida neste nível por 45 minutos. Foram estudados taxa de mortalidade em 72 horas, permeabilidade vascular no pâncreas, porcentagem de água no tecido pancreático, amilase sérica, histologia (edema, necrose acinar e infiltrado inflamatório) e níveis séricos de IL-6 e IL-10. RESULTADOS: Não houve alteração em nenhum dos parâmetros avaliados. CONCLUSÃO: Não há benefício da hipertermia na PA grave experimental induzida por ácido taurocólico.

Captopril, an Angiotensin-converting enzyme inhibitor, attenuates the severity of acute pancreatitis in rats by reducing expression of matrix metalloproteinase 9

It has been reported that matrix metalloproteinase 9 (MMP-9) disrupts basement membrane and increases vascular permeability. MMP-9 therefore might participate in the pathogenesis of severe acute pancreatitis (SAP). Captopril, an angiotensin-converting enzyme inhibitor, could reduce MMP-9 expression. However, the effect of captopril on the outcome of SAP is not ascertained. The aim of this study was to determine whether captopril attenuates the severity of SAP by reducing MMP-9 expression. Thirty Sprague-Dawley rats were randomly divided into 3 groups (n = 10 for each). Rats were given intraperitoneal injection of saline (SAP group) or captopril (4 mg/kg) (treated group), and then given retrograde infusion of 5% sodium taurocholate (1.5 ml/kg) into the pancreatic duct under laparotomy to induce SAP. One group of rats, injected with saline, underwent only sham operation (Control). Experimental samples were collected at 24 hrs after the induction of SAP or sham operation. Various markers of severity of SAP, such as serum levels of amylase and trypsinogen activation peptide and the vascular permeability, were increased in rats with SAP, but were significantly decreased in captopril-treated rats (p < 0.01). Likewise, the serum MMP-9 levels and expression levels of pancreatic tissue MMP-9 were significantly higher in rats with SAP than those in captopril-treated rats and control rats (p < 0.01 for both parameters), but showed no difference between captopril-treated and control rats. These results suggest that captopril may attenuate vascular permeability by reducing MMP-9 expression in SAP, thereby ameliorating severity of the disease. The use of captopril might become a new therapeutic agent for SAP.

Protein kinase C modulates the pulmonary inflammatory response in acute pancreatitis

The present study aims at evaluating the role of protein kinase C (PKC) in the development of acute lung injury, production of inflammatory mediators and expression of adhesion molecules on leukocytes after induction of acute pancreatitis (AP). AP was induced by the intraductal infusion of 5% sodium taurodeoxycholate in the rat. The animals had the PKC inhibitor polymyxin B administered intraperitoneally 30min prior to induction of AP. Levels of protein content, protease activity, cytokines and chemokines in bronchoalveolar lavage fluid (BALF) were assessed 1 and 6h after AP induction. Adhesion molecule expression on leukocytes were measured by flowcytometry. Pretreatment with polymyxin B prevented against acute pancreatitis-induced lung injury and the otherwise occurring increases in TNF-alpha, IL-1beta, MCP-1 and IL-10, as well as against the decreases in IL-2, IFNgamma and TIMP-1, decreased protease activity and down-regulation of CD31, CD54 and CD62L on recruited neutrophils and macrophages in BALF. The results indicate that the leukocyte response in acute pancreatitis vary depending on leukocyte subpopulation. It seems that activation of the PKC signalling pathway may play an important role in pancreatitis-associated lung injury.

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TNF-alpha promotes progression of peritoneal metastasis as demonstrated using a green fluorescence protein (GFP)-tagged human gastric cancer cell line

The mechanisms underlying progression of peritoneal metastasis by gastric cancer after micrometastasis formation remain unclear. In the present study, we investigated metastasis to the abdominal wall peritoneum, one of the major features of peritoneal spread, using a human gastric cancer cell line (GCIY-EGFP) tagged with the green fluorescence protein gene (GFP). This model allows sensitive, specific and sequential observation of metastasis development from the initial deposits to peritoneal carcinomatosis at the end stage. In the initial phase, GCIY-EGFP cells could form micrometastasis selectively on the omentum and mesenterium in a milky spot-dependent manner, but not on abdominal wall peritoneum lacking milky spots until the late stages. In vitro analysis using primary mesothelial cells revealed addition of TNF-alpha to decrease their stress fibers, leading to morphological change followed by exposure of the submesothelial extracellular matrix (ECM) in intercellular gaps. Such TNF-alpha pretreatment was found to enhance attachment of tumor cells to the mesothelial monolayer. When tumor cells were injected into the peritoneal cavity of TNF-alpha pretreated mice, they could metastasize to the abdominal wall peritoneum from the very early stages, resulting in accelerated accumulation of ascites than in TNF-alpha non-pretreatment controls. RT-PCR analysis revealed that tumor cells express cytokines and chemokines, including TNF-alpha. Furthermore, TNF-alpha treatment results in up-regulation of expression of monocyte chemoattractant protein-1 (MCP-1) and IL-8 by mesothelial cells and of TNF-alpha itself by inflammatory leukocytes in the peritoneal cavity. These results suggest that metastasis to the abdominal wall peritoneum occurs as a second step from the first omental metastasis in a milky spot-independent manner and that TNF-alpha derived from tumor cells, mesothelial cells and inflammatory leukocytes in the peritoneal cavity may be involved in the progression of peritoneal metastasis.

Do peritoneal macrophages play an essential role in the progression of acute pancreatitis in rats?

INTRODUCTION

Macrophages are considered to play an essential role in the events leading to systemic inflammatory response. Some are known to reside in the peritoneal cavity but there are no reports defining the participation of peritoneal macrophages (PMs) in the progression of acute pancreatitis.

AIM

To clarify the role of PMs in the progression of acute pancreatitis.

METHODOLOGY

Acute pancreatitis was induced in rats from which macrophages other than PMs were greatly depleted, and in rats greatly depleted of macrophages including PMs. Macrophages were depleted by the injection of liposome encapsulated dichloromethylene bisphosphonate. After the induction of acute pancreatitis, local pancreatic inflammation, intraperitoneal inflammation and lung injury were compared between the 2 groups.

RESULTS

Local pancreatic inflammation did not differ between the 2 groups. However, intraperitoneal inflammation was clearly improved by the depletion of PMs. Serum cytokine level and lung injury were also improved by the depletion of PMs.

CONCLUSION

Peritoneal macrophages extend inflammation from the pancreas to the peritoneal cavity and subsequently induce lung injury in acute pancreatitis. Peritoneal macrophages play an essential role in the systemic inflammatory response and the progression of acute pancreatitis in the rat.

Expression of IL-6 and integrin family cell adhesion molecules in acute necrotizing pancreatitis complicated with multiple organ injury in rats

AIM

To detect the expression of integrin family cellular adhesion molecules LFA-1, Mac-1 and IL-6 in acute necrotizing pancreatitis complicated with multiple organ injury.

METHODS

The flow cytometer was used to detect the expression of LFA-1 and Mac-1 on leukocyte and the radio-immunity to detect the IL-6 in acute necrotizing pancreatitis of rats at different time points.

RESULTS

The expression of LFA-1 and Mac-1 increased significantly in acute pancreatitis group compared with that in control group at all time points (P<0.01), i.e.: LFA-1: 1 h, 7.6±0.4 vs 22.7±1.6; 3 h, 7.9±0.5 vs 26.7±5.5; 6 h, 13.5±1.8 vs 30.3±1.6; 12 h, 9.7±0.7 vs 20.3±4.2; 24 h, 10.1±1.1 vs 15.9±0.7. Mac-1: 1 h, 6.2±1.1 vs 7.0±2.5; 3 h, 6.3±0.8 vs 36.0±1.5; 6 h, 7.9±1.2 vs 27.1±1.4; 12 h, 6.4±0.4 vs 22.5±2.1; 24 h, 7.1±0.4 vs 20.6±1.6. Expression of IL-6 increased significantly in acute pancreatitis group compared with that in control group, i.e.: 1 h, 65.6±3.2 vs 72.4±4.0 (P<0.05); 3 h, 68.2±5.5 vs 155.3±16.3 (P<0.01); 6 h, 69.3±2.6 vs 229.2±16.4 (P<0.01); 12 h, 73.4±2.6 vs 287.7±13.9 (P<0.01); 24 h, 76.9±3.3 vs 289.5±16.1 (P<0.01). Morphological examination demonstrated that inflammatory cells, insterstitial edema, interstitial hemorrhage, desquamation and disintegration occurred in the lungs and kidneys.

CONCLUSION

IL-6, LFA-1 and Mac-1 may play the very active role in acute pancreatitis.