Role of P-selectin and ICAM-1 in pancreatitis-induced lung inflammation in rats: significance of oxidative stress

The role of oxidative stress in chronic obstructive pulmonary disease

Tobacco smoke is the number one risk factor for chronic obstructive pulmonary disease (COPD) and contains a high concentration of oxidants. The lung has a high concentration of antioxidants and antioxidant enzymes; however, COPD patients show evidence of increased oxidative stress suggesting that endogenous antioxidants may be insufficient to prevent oxidative damage from cigarette smoke. The consequences of increased oxidative stress in the lung include increased transcription of inflammatory genes, increased protease activity, and increased mucus secretion. Oxidative stress is often associated with impaired skeletal muscle function and may be one of the causes of glucocorticoid resistance. While current pharmacologic approaches to the treatment of chronic obstructive pulmonary disease do not commonly include antioxidants, preclinical studies involving animal models suggest that antioxidant superoxide dismutase mimetics offer a potential new therapeutic approach to the prevention and treatment of chronic obstructive pulmonary disease.

Oxygen radicals promote ICAM-1 expression and microcirculatory disturbances in experimental acute pancreatitis

BACKGROUND/AIMS

The course of pancreatitis is paralleled by a drastic reduction in organ perfusion and increased ICAM-1-mediated leukocyte-endothelial interaction. We aimed to evaluate the effect of oxygen radicals on ICAM-1 expression and the microcirculation in severe acute pancreatitis using the oxygen radical scavenger dimethylsulfoxide (DMSO).

MATERIALS AND METHODS

Severe pancreatitis was induced in rats (n = 32) who were randomly assigned to one of two groups: either 4 ml/kg 50% DMSO/saline (v/v) started 3 h after induction of pancreatitis or 4 ml/kg saline (control). Microcirculation was evaluated by intermittent intravital microscopy. Serum amylase and lipase, histomorphometric changes, immunohistochemistry for ICAM-1 expression and 24-hour survival were investigated.

RESULTS

Leukocyte adherence was significantly reduced (4.4 +/- 0.47 vs. 5.58 +/- 0.69 sticker/100 micro m, p < 0.05), and mean capillary (0.96 +/- 0.06 vs. 0.45 +/- 0.13 mm/s; p < 0.01) and venous erythrocyte velocity (1.16 +/- 0.12 vs. 0.58 +/- 0.16 mm/s, p < 0.01) were significantly increased by DMSO treatment. Microcirculatory disturbances were paralleled by an increase in endothelial ICAM-1 expression, whereas DMSO reduced ICAM-1 expression.

CONCLUSION

DMSO improves pancreatic microcirculation and reduces ICAM-1 expression and subsequent leukocyte adhesion, suggesting an important role of oxygen free radicals in the pathway of endothelial ICAM-1 expression and microcirculatory disturbances in acute pancreatitis.

Ischaemia–reperfusion is an event triggered by immune complexes and complement

Background

Reperfusion injury is a common clinical problem that lacks effective therapy. Two decades of research implicating oxygen free radicals and neutrophils has not led to a single successful clinical trial.

Methods

The aim was to review new clinical and preclinical data pertaining to the alleviation of reperfusion injury. A review of the literature was undertaken by searching the MEDLINE database for the period 1966–2003 without language restrictions.

Results and conclusion

Evidence now points to complement and immune complexes as critical players in mediating reperfusion injury. Ischaemia is postulated to induce a phenotypical cellular change through the surface expression of a neoantigen. Preformed circulating natural IgM antibodies are then trapped and complement is activated. Final events leading to reperfusion injury include formation of the membrane attack complex and mast cell degranulation.

Role of fibronectin in pancreatitis-associated lung injury

Acute pancreatitis (AP) in humans can lead to increased vascular permeability in the lungs and respiratory failure. Fibronectin plays an important role in maintaining the structural integrity of the pulmonary epithelium and endothelium. However, its importance in pancreatitis-associated lung injury has not been defined. AP was produced by infusing caerulein (5 ug/kg/hr) in rats for 8 or 24 hr. Lung injury was assessed histologically and by determining lung microvascular permeability by bronchoalveolar lavage (BAL) analysis. Organ distribution of a target particle given intravenously was determined by the vascular clearance of magnetic iron oxide particles. Plasma fibronectin was measured by the enzyme-linked immunosorbent assay technique. After 8 hr of cerulein infusion, serum amylase increased 8-fold. Pancreatitis correlated with lung injury. BAL at 8 hr showed a 90% increase (P < 0.05) in albumin levels. Histological analysis at 8 hr revealed an increased number of leukocytes within the lungs. By 8 hr, plasma fibronectin significantly decreased 25% (P < 0.05) and the pulmonary uptake of iron oxide increased 111% (P < 0.05). By 24 hr, these effects had nearly resolved. These results indicate that decreases in serum fibronectin and increases in pulmonary leukocyte margination during acute pancreatitis may compromise the integrity of the air-blood barrier and also increase the pulmonary uptake of circulating pathogenic materials, thus making lung injury more likely.

The pancreatitis-associated protein induces lung inflammation in the rat through activation of TNFalpha expression in hepatocytes

The pancreatitis-associated protein (PAP) is a pancreatic stress protein overexpressed during acute pancreatitis, a disease often accompanied by lung inflammation. We investigated whether PAP was involved in the occurrence of this remote complication of pancreatitis and whether the liver might be implicated in the process. PAP was injected into the vena cava of rats (40 or 400 micro g/kg body weight). For comparison, pancreatitis was induced in rats by intraductal administration of sodium taurocholate. Three hours later, parameters of inflammation and mRNA concentrations of TNFalpha, P-selectin, heat shock protein (HSP)-70, and extracellular superoxide dismutase (EC-SOD) were monitored in lung and liver. Significant increases in P-selectin expression, neutrophil infiltration, and oxidative stress revealed that PAP treatment induced lung inflammation in rats and exacerbated inflammation in animals with pancreatitis. Plasma TNFalpha level was increased and TNFalpha mRNA was strongly overexpressed in liver, with concomitant activation of NF-kappaB; in situ hybridization revealed that TNFalpha overexpression was mainly located to hepatocytes. Lung inflammation induced by PAP could be prevented by injection of anti-TNFalpha antibodies. It was concluded that, during pancreatitis, PAP released by the pancreas could mediate lung inflammation through induction of hepatic TNFalpha expression and subsequent increase in circulating TNFalpha.

Heparin mobilizes xanthine oxidase and induces lung inflammation in acute pancreatitis

OBJECTIVE

To evaluate the effect of low molecular weight heparin on plasma xanthine oxidase concentrations and lung inflammatory response during acute pancreatitis.

DESIGN

Randomized, controlled trial.

SETTING

Experimental laboratory.

SUBJECTS

Male Wistar rats.

INTERVENTIONS

Acute pancreatitis was induced by intraductal administration of 5% sodium taurocholate. Low molecular weight heparin (0, 30, 90, or 300 units/kg) was administered immediately after induction of pancreatitis.

MEASUREMENTS AND MAIN RESULTS

Lipase and xanthine oxidase plasma concentrations were measured 3 hrs after pancreatitis induction. Expression of P-selectin messenger RNA and myeloperoxidase activity as a marker of neutrophil infiltration were determined in the lung. An increase in xanthine oxidase plasma concentrations was observed during pancreatitis. Administration of heparin also increased plasma xanthine oxidase activity in both control and pancreatitis animals. Measures of xanthine oxidase present in the endothelial surface indicate that during pancreatitis, the enzyme is released from the gastrointestinal endothelium. By contrast, heparin mobilizes xanthine oxidase from almost all organs evaluated. Neutrophil infiltration was increased in the lung during pancreatitis. Heparin administration further increased, in a dose-dependent manner, myeloperoxidase activity and P-selectin expression in the lung in animals with pancreatitis. By contrast, in control animals, heparin had no effect on myeloperoxidase activity and did not induce P-selectin up-regulation.

CONCLUSION

During acute pancreatitis, heparin administration might mobilize xanthine oxidase attached to endothelial cells, originating a free radical-generating system in the circulation that would trigger an inflammatory response in the lung.

P-selectin upregulation in bleomycin induced lung injury in rats: effect of N-acetyl-L-cysteine

BACKGROUND

A number of adhesion molecules are involved in the process of neutrophil infiltration into the lung. P-selectin is one of these neutrophil-endothelial cell adhesion molecules. A study was undertaken to examine the involvement of P-selectin in the development of bleomycin induced inflammation and the ability of N-acetyl-L-cysteine to reduce the potential expression of this selectin in rats.

METHODS

N-acetyl-L-cysteine (3 mmol/kg po) was administered daily for seven days prior to bleomycin administration (2.5 U/kg). The kinetics of P-selectin expression and the effect of N-acetyl-L-cysteine after bleomycin treatment were measured using radiolabelled antibodies. P-selectin localisation was evaluated by immunohistochemistry and neutrophil infiltration was assessed by myeloperoxidase activity.

RESULTS

Bleomycin administration resulted in an upregulation of P-selectin at 1 hour, returning to baseline at 3 hours. Myeloperoxidase activity showed a significant increase at 6 hours after bleomycin administration that lasted for 3 days. N-acetyl-L-cysteine treatment completely prevented these increases.

CONCLUSION

Upregulation of P-selectin in the lung is associated with neutrophil recruitment in response to bleomycin. The beneficial effect of N-acetyl-L-cysteine on bleomycin induced lung injury may be explained in part by the prevention of neutrophil recruitment in the inflammatory stage of the disease.

Ischemic preconditioning: a defense mechanism against the reactive oxygen species generated after hepatic ischemia reperfusion

BACKGROUND

Preconditioning protects against both liver and lung damage after hepatic ischemia-reperfusion (I/R). Xanthine and xanthine oxidase (XOD) may contribute to the development of hepatic I/R.

OBJECTIVE

To evaluate whether preconditioning could modulate the injurious effects of xanthine/XOD on the liver and lung after hepatic I/R.

METHODS

Hepatic I/R or preconditioning previous to I/R was induced in rats. Xanthine and xanthine dehydrogenase/xanthine oxidase (XDH/XOD) in liver and plasma were measured. Hepatic injury and inflammatory response in the lung was evaluated.

RESULTS

Preconditioning reduced xanthine accumulation and conversion of XDH to XOD in liver during sustained ischemia. This could reduce the generation of reactive oxygen species (ROS) from XOD, and therefore, attenuate hepatic I/R injury. Inhibition of XOD prevented postischemic ROS generation and hepatic injury. Administration of xanthine and XOD to preconditioned rats led to hepatic MDA and transaminase levels similar to those found after hepatic I/R. Preconditioning, resulting in low circulating levels of xanthine and XOD activity, reduced neutrophil accumulation, oxidative stress, and microvascular disorders seen in lung after hepatic I/R. Inhibition of XOD attenuated the inflammatory damage in lung after hepatic I/R. Administration of xanthine and XOD abolished the benefits of preconditioning on lung damage.

CONCLUSIONS

Preconditioning, by blocking the xanthine/XOD pathway for ROS generation, would confer protection against the liver and lung injuries induced by hepatic I/R.

Lung injury in acute pancreatitis: mechanisms, prevention, and therapy

Lung injury is the most pertinent manifestation of extra-abdominal organ dysfunction in pancreatitis. The propensity of this retroperitoneal inflammatory condition to engender a diffuse and life-threatening lung injury is significant. Approximately one third of patients will develop acute lung injury and acute respiratory distress syndrome, which account for 60% of all deaths within the first week. The variability in the clinical course of pancreatitis renders it a vexing entity and makes demonstration of the efficacy of any specific intervention difficult. The distinct pathologic entity of pancreatitis-associated lung injury is reviewed with a focus on etiology and potential therapeutic maneuvers.

FR167653 improves survival and pulmonary injury after partial hepatectomy under ischemia/reperfusion in rats

BACKGROUND

FR167653 is a potent suppressant of production of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta, which play an important role in hepatic and pulmonary injury due to ischemia/reperfusion of the liver and in liver regeneration after hepatectomy. We examined the effects of FR167653 on hepatectomy under ischemia/reperfusion in rats.

METHODS

After initial 15-min ischemia and 5-min reperfusion, 70% hepatectomy was performed during the second 15-min ischemia period in FR167653-treated (FR group) and saline-treated (saline group) rats. The survival rate, relative liver weight, TNF-alpha, IL-1 beta, DNA synthesis rate of the remnant liver, and histological change and adhesion molecule (ICAM-1) of the lung were examined. Serum glutamic pyruvic transaminase and hepatic malondialdehyde were also measured.

RESULTS

Expressions of TNF-alpha and IL-1 beta in the remnant liver were significantly inhibited in the FR group compared to the saline group. The survival was significantly better and pulmonary damage was less in the FR group after hepatectomy under ischemia/reperfusion. ICAM-1 expression of the lung was not altered after hepatectomy and was not significantly different between the two groups. Liver regeneration and injury were not significantly different between the two groups.

CONCLUSION

FR167653 does not affect liver injury and regeneration after hepatectomy under ischemia/reperfusion, while it ameliorates pulmonary injury and improves the survival.

Endothelial-derived selectins in the development of organ dysfunction in acute pancreatitis

OBJECTIVE

The development of organ dysfunction is the principal determinant of outcome in acute pancreatitis and is mediated through a systemic inflammatory response characterized by leukocyte and endothelial cell activation. Up-regulation of the endothelial cell adhesion molecules, E-selectin and P-selectin, is important for endothelial/leukocyte interactions. Levels of serum-soluble E-selectin and P-selectin have been suggested as markers of endothelial activation. This study examines the kinetics of serum-soluble selectins in patients with acute pancreatitis complicated by organ dysfunction.

DESIGN

Prospective observational study.

SETTING

University teaching hospital with a specialist hepato-pancreatico-biliary service.

PATIENTS

Eighteen patients with acute pancreatitis were studied, nine of whom had organ dysfunction.

MEASUREMENTS AND MAIN RESULTS

Serial venous blood samples were collected on the first 3 days after admission for measurement of soluble E-selectin and P-selectin by enzyme-linked immunosorbent assay. In all patients, soluble P-selectin concentrations decreased significantly during the study period. Nonsurvivors had significantly higher levels of soluble P-selectin than survivors. In contrast, soluble E-selectin increased significantly during the study period in patients with organ dysfunction, whereas it remained constant in patients without evidence of organ dysfunction.

CONCLUSIONS

These results suggest a role for endothelial-derived selectins in the development of organ dysfunction in patients with acute pancreatitis. The observed temporal differences in serum selectin concentrations is in keeping with in vitro observations of endothelial selectin expression.

Differential upregulation of cellular adhesion molecules at the sites of oxidative stress in experimental acute pancreatitis

BACKGROUND

Severe acute pancreatitis (AP)(2) is associated with exaggerated leukocyte adherence and activation. Endothelial cellular adhesion molecules (CAMs) can be induced by cytokines, but also directly by oxygen free radicals (OFRs), mediated by nuclear factor kappa-B (NF-kappa B). We investigated the behavior of inducible CAMs in relation to pancreatic oxidative stress. Our novel modification of cerium capture histochemistry (reaction of OFRs with cerium produces laser reflective Ce perhydroxide precipitates) combined with reflectance confocal laser scanning microscopy (CLSM) allows the histological codemonstration of in vivo OFR production and immunolabeled CAMs, or NF-kappa B.

METHODS

Taurocholate AP was induced in rats; sham operated and normal animals served as controls. To achieve in situ, in vivo reaction of cerium with OFRs, animals were perfused with CeCl(3) solution at different time points (1, 2, 8, 24 h) and then sacrificed. E-selectin, P-selectin, ICAM-1, VCAM, and NF-kappa B p65 were labeled by immunofluorescence (IF) on frozen sections of cerium perfused pancreata. IF and Ce perhydroxide reflectance were simultaneously detected by CLSM. Pancreatic gene expression of the same CAMs was quantified by competitive RT-PCR (MIMIC internal control).

RESULTS

Control pancreata showed negligible reflectance and minimal CAM expression. Early (1, 2 h) AP samples were characterized by intense, heterogeneous acinar OFR production, strong P-selectin, and increasing ICAM expression, with nuclear translocation of p65, histologically all colocalizing with the areas of acinar oxidative stress. Adherent polymorphonuclear leukocytes (PMNs) displayed weak OFR formation. Later (8, 24 h), a slowly declining P-selectin, but persisting ICAM-1 expression, was paralleled by widespread adherence of PMNs producing surprisingly large amounts of OFRs. VCAM and E-selectin showed a mild increase at 24 h. CAM gene activation was in good correlation with the protein expression.

CONCLUSIONS

The early acinar oxidative stress is colocalized with NF-kappa B activation, preferential P-selectin, and ICAM upregulation in this AP model. Subsequently, adherent, activated PMNs become the major source of OFRs, thereby contributing to tissue damage.

Endothelial sulfated sialyl Lewis x glycans, putative L-selectin ligands, are preferentially expressed in bronchial asthma but not in other chronic inflammatory lung diseases

Lymphocyte infiltrate is a hallmark of inflammatory responses. We have previously shown that de novo-induced endothelial sialyl Lewis x (sLex) expression guides lymphocytes in an L-selectin-dependent manner to sites of acute organ transplant rejections. In this research, we have analyzed five groups of chronic lung inflammations to determine the presence of properly glycosylated, i.e., sulfated, sLex-decorated, L-selectin ligands. Two anti-sLex (2F3 and HECA-452) and one anti-6- and/or 6'-sulfated and/or 6,6'-bisulfated (MECA-79) monoclonal antibodies (mAbs) were used. The control lung specimens did not express L-selectin ligands on endothelium. In contrast, the endothelial staining intensity and the number of positive peribronchial venules and capillaries with mAbs 2F3, HECA-452, and MECA-79 were significantly greater in bronchial biopsies from patients with asthma compared with normal specimens (P<0.003). However, no significant increase of peribronchial endothelial reactivity with these antibodies was observed in adult respiratory distress syndrome, chronic bronchitis, fibrosing alveolitis, and granulomatous inflammation compared with controls. These data suggest that sulfated sLex glycans, acting putatively as ligands for L-selectin, could be instrumental in lymphocyte extravasation into human peribronchial lung tissue during asthma, but not so important in several other inflammatory lung diseases.

Pancreatitis induces HSP72 in the lung: role of neutrophils and xanthine oxidase

The aim of this work was to evaluate the systemic Hsp72 expression in rat lung and liver in vivo in a model of acute pancreatitis and investigate the possible involvement of xanthine oxidase and neutrophils in this process. Pancreatitis was induced by intraductal administration of 5% sodium taurocholate and samples of lung and liver were obtained 1 and 3 h later. In some groups of rats circulating xanthine oxidase was inhibited with oxypurinol, and neutrophil recruitment was blocked with a monoclonal antibody against P-selectin. Hsp72 expression was assessed by means of Western blot and immunohistochemistry. Results showed Hsp72 induction in lung, but not in liver, shortly after pancreatitis. Hsp72-induced expression was located in bronchial epithelium, alveolar macrophages, infiltrating neutrophils, and blood vessels. Oxypurinol and the antibody against P-selectin prevented pancreatitis-induced lung Hsp72 overexpression suggesting that Hsp72 induction is mediated by neutrophil infiltration into the lungs.

H(2)O(2) and PARS mediate lung P-selectin upregulation in acute pancreatitis

P-selectin and circulating xanthine oxidase are involved in the process of neutrophil infiltration into the lung associated with acute pancreatitis. This study investigated the mediators that trigger the upregulation of P-selectin in this process. Pancreatitis was induced in rats by intraductal administration of 5% sodium taurocholate. P-selectin expression was measured using radiolabeled antibodies. Neutrophil infiltration and PAF levels were also evaluated. The role of superoxide radical, H(2)O(2), or the enzyme poly (ADP-ribose) synthetase (PARS) on these processes was determined in groups of animals treated with the corresponding inhibitors. Pancreatitis was associated with an increase in P-selectin expression in the lung. Inhibition of PARS or H(2)O(2) abrogated P-selectin upregulation, PAF generation, and neutrophil recruitment. Superoxide dismutation prevented neutrophil recruitment and PAF generation, but had no effect on P-selectin expression. We conclude that during acute pancreatitis, upregulation of P-selectin in the pulmonary endothelium is triggered by H(2)O(2) and PARS activity.