Effect of endothelin and endothelin receptor blockade on capillary permeability in experimental pancreatitis

[Clinical Manifestations of Early-Onset Capillary Leak Syndrome in Patients With Multiple Organ Failure Due to Severe Acute Pancreatitis]

Objective

To investigate the early dynamic changes of biomarkers associated with capillary leak syndrome (CLS) in patients with severe acute pancreatitis (SAP) and their correlation with multiple organ failure (MOF).

Methods

A total of 171 SAP patients admitted to the West China Centre of Excellence for Pancreatitis, West China Hospital, Sichuan University between September 1, 2019 and December 31, 2020 were enrolled for this study. The patients were divided into MOF and non-MOF groups based on the occurrence of MOF in the first 5 days of hospitalization, and were further divided into subgroups based on the presence of moderate-to-severe intra-abdominal hypertension (IAH). We performed dynamic monitoring of the blood biomarkers (hematocrit [HCT], blood urea nitrogen [BUN], and creatinine [Cr]), plasma proteins (albumin [Alb], total protein [TP], and non-albumin plasma proteins [NAPP]), and intra-abdominal pressure. Trends in these indicators across groups were analyzed comprehensively.

Results

No significant differences in baseline data between the two groups were observed. The baseline data of the 2 groups were comparable. The MOF group had significantly higher rates of persistent systemic inflammatory response syndrome (SIRS) lasting 48 hours (91.3% vs. 71.8%), ICU admission (70.4% vs. 17.6%), and length-of-stay ([32 ± 17.7] days vs. [19.0 ± 12.2] days) compared to those of the non-MOF group (P < 0.05). The incidences of respiratory, circulatory, and renal failures were higher in the MOF group than those in the non-MOF group, showing significant differences in circulatory failure (69% vs. 3.5%) and renal failure (65.5% vs. 3.5%) (P < 0.05). In the first 5 days of hospitalization, the MOF group showed significantly elevated BUN and Cr levels, while Alb and TP levels dropped rapidly upon admission and then gradually recovered. The NAPP level of the MOF group continued to decrease after admission, and on the third day after admission, the NAPP level was lower than that of the Non-MOF group, showing statistically significant difference (P < 0.001). The Alb/NAPP ratio of the MOF group decreased significantly on day 1 and then rapidly increased, showing significant differences between the groups on days 3 and 4 (P = 0.001). Subgroup analysis of MOF patients with moderate-to-severe IAH revealed similar trends in the dynamic changes and the overall changes in the indicators, and the difference was even more pronounced. The mixed linear model showed that the average levels of HCT, BUN, Alb/NAPP, and Alb/TP were higher and increased over time in the MOF combined with IAP subgroup (P < 0.001).

Conclusion

The CLS model of SAP patients is validated, confirming that CLS is a key factor in the progression from SIRS to MOF. The loss of NAPP is an early and important indicator of CLS persistence and progression to MOF. Additionally, moderate-to-severe IAH accelerates the deterioration of MOF. These findings provide valuable insights into the potential mechanisms of MOF and warrant further validation through large-scale prospective studies.

Value of Dual-Energy CT Perfusion Analysis in Patients with Acute Pancreatitis: Correlation and Discriminative Diagnostic Accuracy with Varying Disease Severity

Background: This study investigates the correlation and discriminative diagnostic accuracy of dual-energy CT (DECT)-derived imaging biomarkers in patients with acute pancreatitis of varying severity. Methods: In this retrospective study, we included 51 patients with acute pancreatitis who had undergone portal-venous phase DECT of the abdomen. Three blinded readers independently performed region-of-interest measurements on DECT images in the inflammatory pancreatic parenchyma. The correlation between modified CT severity index (CTSI) and quantitative imaging parameters was investigated using Pearson correlation coefficient. We performed receiver operator curve (ROC) analysis to assess diagnostic accuracy of the quantitative image parameters for the differentiation between mild/moderate versus severe acute pancreatitis. The optimal discriminative cut-off value to diagnose severe acute pancreatitis was determined using the Youden index. Results: Moderate correlations were found between CTSI scores and iodine density (Pearson’s correlation coefficient r = −0.65; p < 0.001), as well as attenuation (r = −0.55; p < 0.001) and normalized iodine uptake (r = −0.50; p < 0.001). ROC curve analysis revealed highest ability to differentiate mild/moderate from severe acute pancreatitis for iodine density (AUC = 0.86, 95% confidence interval 0.75 to 0.97). An optimal iodine density threshold of ≤1.63 mg/mL was found to indicate severe acute pancreatitis with a sensitivity of 81.3% and specificity of 77.1%. Conclusion: DECT-derived iodine density correlates with acute pancreatitis severity and may facilitate prediction of severe acute pancreatitis.

Treatment of Microcirculatory Disturbances in Acute Pancreatitis: Where Are We Now?

Acute pancreatitis is a serious inflammatory condition. Research has shown an increase in the number of pancreatitis-associated hospitalizations, with a marked decline in the mortality rates down to 0.79% in patients with acute pancreatitis and 0.26% in patients with exacerbation of chronic pancreatitis. Up to one-third of patients develop pancreatic tissue necrosis, with a mortality rate of 30%. One of the mechanisms is the disturbances in pancreatic microcirculation due to the release of endothelin, a long-acting vasoconstrictor. The development of pancreatitis causes the release of other inflammatory mediators, which reduce blood flow in the microcirculation. The activation of intracellular trypsinogen initiates a cascade of mechanisms in pancreatitis. There is no specific treatment for acute pancreatitis. Protease inhibitors are not effective in treating severe acute pancreatitis. There is an important role of low-molecular-weight heparin in attenuating necrosis and restoring perfusion of the pancreas. Other drugs used are endothelin receptor antagonists, antagonist of interleukin-1 and interleukin-6 receptors, α-tocopherol, tumor necrosis factor-α and platelet-activating factor inhibitors, acetylsalicylic acid, and local intra-arterial injection of lidocaine. The prophylactic use of antibiotics is not recommended. The treatment outcome of acute pancreatitis is still unsatisfactory.

Molecular Dambusters: What Is Behind Hyperpermeability in Bradykinin-Mediated Angioedema?

In the last few decades, a substantial body of evidence underlined the pivotal role of bradykinin in certain types of angioedema. The formation and breakdown of bradykinin has been studied thoroughly; however, numerous questions remained open regarding the triggering, course, and termination of angioedema attacks. Recently, it became clear that vascular endothelial cells have an integrative role in the regulation of vessel permeability. Apart from bradykinin, a great number of factors of different origin, structure, and mechanism of action are capable of modifying the integrity of vascular endothelium, and thus, may participate in the regulation of angioedema formation. Our aim in this review is to describe the most important permeability factors and the molecular mechanisms how they act on endothelial cells. Based on endothelial cell function, we also attempt to explain some of the challenging findings regarding bradykinin-mediated angioedema, where the function of bradykinin itself cannot account for the pathophysiology. By deciphering the complex scenario of vascular permeability regulation and edema formation, we may gain better scientific tools to be able to predict and treat not only bradykinin-mediated but other types of angioedema as well.

Comparison of pancreatic microcirculation profiles in spontaneously hypertensive rats and Wistar-kyoto rats by laser doppler and wavelet transform analysis

Pancreatic microcirculatory dysfunction emerged as a novel mechanism in the development of hypertension. However, the changes of pancreatic microcirculation profiles in hypertension remain unknown. Pancreatic microcirculatory blood distribution pattern and microvascular vasomotion of spontaneously hypertensive rats (SHRs) and Wistar Kyoto rats (WKYs) were determined by laser Doppler. Wavelet transform analysis was performed to convert micro-hemodynamic signals into time-frequency domains, based on which amplitude spectral scalograms were constructed. The amplitudes of characteristic oscillators were compared between SHRs and WKYs. The expression of eNOS was determined by immunohistochemistry, and plasma nitrite/nitrate levels were measured by Griess reaction. Additionally, endothelin-1, malondialdehyde, superoxide dismutase and interleukin-6 were determined by enzyme-linked immunosorbent assay. SHRs exhibited a lower scale blood distribution pattern with decreased average blood perfusion, frequency and amplitude. Wavelet transform spectral analysis revealed significantly reduced amplitudes of endothelial oscillators. Besides reduced expression of eNOS, the blood microcirculatory chemistry complements micro-hemodynamic profiles as demonstrated by an increase in plasma nitrite/nitrate, endothelin-1, malondialdehyde, interleukin-6 and a decrease of superoxide dismutase in SHRs. Here, we described abnormal pancreatic microcirculation profiles in SHRs, including disarranged blood distribution pattern, impaired microvascular vasomotion and reduced amplitudes of endothelial oscillators.

Effects of Yue-Bi-Tang on water metabolism in severe acute pancreatitis rats with acute lung-kidney injury

BACKGROUND

The complications acute lung injury and acute kidney injury caused by severe inflammation are the main reasons of high mortality of severe acute pancreatitis (SAP). These two complications can both lead to water metabolism and acid-base balance disorders, which could act as additional critical factors affecting the disease trend. Aquaporins (AQPs), which can regulate the transmembrane water transport, have been proved to participate in the pathophysiological process of SAP and the associated complications, such as acute lung injury and acute kidney injury. Thus, exploring herbs that can effectively regulate the expression of AQP in SAP could benefit the prognosis of this disease.

AIM

To determine whether Yue-Bi-Tang (YBT) can regulate the water metabolism in rats with severe acute pancreatitis via regulating the expression of aquaporins.

METHODS

Sprague-Dawley rats were randomly divided into three groups, sham operation group (SOG), model group (MG), and treatment group (TG). SAP was induced with 3.5% sodium taurocholate in the MG and TG. Rats in the TG were administered with YBT while SOG and MG rats were given the same volume of saline. Blood and tissue samples were harvested to detect serum inflammatory cytokines, histopathological changes, malondialdehyde and superoxide dismutase in the lung, and protein and mRNA expression of kidney injury molecule-1, α-smooth muscle actin, and vimentin in the kidney, and AQP1 and 4 in the lung, pancreas, and kidney.

RESULTS

The serum interleukin-10, tumor necrosis factor α, and creatinine levels were higher in the MG than in the SOG. Tumor necrosis factor α level in the TG was lower than that in the MG. Malondialdehyde level in lung tissues was higher than in the SOG. The pathological scores and edema scores of the pancreas, lung, and kidney tissues in the MG were all higher than those in the SOG and TG. The protein expression of AQP4 in lung tissues and AQP1 in kidney tissues in the MG were higher than those in the SOG and TG. The expression of vimentin was significantly higher in the MG than in the SOG. The expression of AQP1 mRNA in the lung and kidney, and AQP4 mRNA in the kidney was up-regulated in the MG compared to the SOG.

CONCLUSION

YBT might regulate water metabolism to reduce lung and kidney edema of SAP rats via decreasing AQP expression, and alleviate the tissue inflammatory injury.

Impacts of albumin synergized with hydroxyethyl starch on early microvascular albumin leakage after major abdominal surgery in rabbits

PURPOSE

To investigate the impacts of albumin synergized with hydroxyethyl starch (HES) on early microvascular albumin leakage after major abdominal surgery in rabbits.

METHODS

Forty male Japanese rabbits were randomly divided into four groups: the control group, the saline group, the albumin group, and the Syn group (hydroxyethyl starch+albumin). The latter three groups were performed gastrectomy plus resection of pancreatic body and tail and splenectomy. The serum albumin concentration was detected before and 48h after surgery, and the conditions of mesenteric microvascular leakage in these 4 groups were observed under microscope 48 h after surgery to calculate the leakage rate.

RESULTS

Compared with the saline group, the albumin group and the Syn group exhibited significantly increased serum albumin concentrations 48h after surgery (P<0.05). The albumin leakage rate was the most obvious in the albumin group, followed by the saline group, while that in the Syn group was the minimal, and there existed significant differences among these groups (P<0.05) .

CONCLUSION

Simple administration of albumin in the early stage after major abdominal surgery could increase the albumin leakage, while the synergization of albumin and hydroxyethyl starch could reduce the albumin leakage.

Effect of mesenchymal stem cells on small intestinal injury in a rat model of acute necrotizing pancreatitis

BACKGROUND

Acute necrotizing pancreatitis (ANP) is often complicated by multiple organ failure. The small intestine is frequently damaged during ANP. Capillary leakage in multiple organs during ANP is one of the most important causes of multiple organ dysfunction. Damage to the capillary endothelial barrier and impaired water transportation could lead to capillary leakage in ANP.

METHODS

Sprague-Dawley (SD) rats were randomized into a control group, the ANP group, the culture media-treated group, or the bone marrow-derived mesenchymal stem cell (BMSC)-treated group (30 rats in each group). Ten rats in each group were sacrificed at 6, 12, and 24 h after induction of experimental models. Serum, ascites, pancreatic, and small intestinal samples were collected. The levels of serum and ascites albumin and amylases were measured, pancreatic histology was assessed, and the connection changes between vessel endothelial cells were evaluated using scanning electron microscopy (SEM). Capillary leakage in small intestinal tissue was observed visually by tracking fluorescein isothiocyanate (FITC)-albumin, and was measured by the Evans blue extravasation method. The location and expression of aquaporin 1 (AQP1) in the small intestine was analyzed using immunohistochemistry, real-time polymerase chain reaction (PCR), and Western blot.

RESULTS

The outcomes showed that the level of serum and ascites amylase is elevated. Conversely, the level of serum albumin is decreased while ascites albumin is elevated. There is damage to pancreatic tissue, and the small intestinal capillary endothelial barrier was aggravated. Furthermore, the expression of AQP1 was reduced significantly after induced ANP. Following treatment with MSCs, the elevation of amylase and the decrease of serum albumin were inhibited, the damage to pancreatic tissue and the level of small intestinal capillary leakage was alleviated, and the downregulation of AQP1 was reversed.

CONCLUSIONS

In conclusion, MSC therapy could alleviate small intestinal injury in rats with ANP, the mechanism of which might be related to reduction of damage to the small intestinal capillary endothelial barrier, and increased expression of AQP1 in the small intestine.

How does cigarette smoking cause acute pancreatitis?

INTRODUCTION

Acute Pancreatitis (AP) is an emerging health problem world-wide and it is a major cause of admissions for gastrointestinal disease in many countries. Amongst the more common causes (alcohol and gallstones), recent evidence has emerged indicating that smoking is an independent risk factor for AP. However, the mechanisms involved in smoking-induced AP have not been completely elucidated. This review puts together all the published evidence in literature to present the clinical and laboratory evidence relating smoking to the causation of AP.

DISCUSSION

The two main metabolites from cigarette smoke, namely nicotine and NNK are able to induce functional and histological changes within the pancreas consistent with AP. The major mechanisms involved include their action on acinar cells and zymogen secretion through pathways involving CCK and the nicotinic preganglionic receptors. Effects on the pancreatic microvasculature may be mediated through the nitric oxide pathway. There is indirect evidence to suggest that nicotine and acrolein may lead to CFTR dysfunction thereby influencing ductal secretion. However, direct evidence for this effect is needed. The effect of cigarette smoke metabolites on stellate cells and the islets warrants further investigation in the context of pathogenesis of AP.

CONCLUSION

Using a step-wise approach, the review revisits the effects of the various metabolites of cigarette smoke on the constituents of the pancreas (exocrine, endocrine, neurohormonal, stellate cells, ductal system) and highlights their proven, and potential, mechanisms in triggering off an attack of AP.

Early Predictors of Fluid Sequestration in Acute Pancreatitis: A Validation Study

OBJECTIVES

The primary aim of this retrospective study was to externally validate predictors of increased fluid sequestration at 48 hours (FS⁴⁸) in acute pancreatitis (AP).

METHODS

Patients admitted between January 10 and February 13 with a diagnosis of AP were evaluated. The FS⁴⁸ was calculated as difference between total fluid input and output in the first 48 hours. Predictors of FS⁴⁸, such as young age, alcoholic etiology, hemoconcentration, hyperglycemia, and systemic inflammatory response syndrome (SIRS), and outcomes in AP, such as increased length of stay, acute fluid collection(s), necrosis, and persistent organ failure (POF), were defined in accordance with the previous study. Linear regression analysis was performed to evaluate the association between predictors and outcome.

RESULTS

Two hundred twenty-seven AP patients (mean age, 48 years; 54% men) with a median FS⁴⁸ of 4.2 L were evaluated. Age younger than 40 years, alcoholic etiology, hemoconcentration, and SIRS independently predicted increased FS⁴⁸ (P < 0.05). Increased FS⁴⁸ was associated with persistent SIRS and POF (P < 0.01). There was a significant trend between number of predictors and FS (P < 0.001). The presence of 4 predictors or more was associated with higher rates of persistent SIRS and POF (P < 0.01).

CONCLUSIONS

Our study validated 4 of 5 predictors of increased FS⁴⁸ from the previous study. Presence of 4 predictors or more and increased FS⁴⁸ are both associated with persistent SIRS and POF.

Inverted U-Shaped Relationship between Central Venous Pressure and Intra-Abdominal Pressure in the Early Phase of Severe Acute Pancreatitis: A Retrospective Study

OBJECTIVE

Many studies have indicated that intra-abdominal pressure (IAP) is positively correlated with central venous pressure (CVP) in severe cases. However, although elevated IAP is common in patients with severe acute pancreatitis (SAP), its relationship with CVP remains unclear. Our study aimed to investigate the association of IAP with CVP in early-phase SAP patients.

METHODS

In total, 116 SAP patients were included in this retrospective study. On the first day of hospitalization, blood samples were collected for biochemical examination and cytokine concentration monitoring. Additionally, a urinary catheter and right subclavian vein catheter were inserted for IAP and CVP measurement, respectively. Other routine clinical data were also recorded.

RESULTS

Within 24 hours after hospitalization, CVP fluctuated and increased with increasing IAP up to 15.7 mmHg (P = 0.054) but decreased with increasing IAP when the IAP was > 15.7 mmHg (P < 0.001). After adjusting for abdominal perfusion pressure (APP) and mean arterial pressure (MAP), a similar distribution was observed. An inverted U-shaped trend between IAP and CVP was also present in the groups classified according to the patient's sex, local complications, ascites, and serum amylase levels.

CONCLUSIONS

CVP and IAP have an inverted U-shaped relationship, with a peak at an IAP of 15.7 mmHg in the early phase of SAP. After this peak, CVP decreases as IAP increases. These results have crucial implications for clinical fluid resuscitation in SAP patients. In particular, because one CVP value might be correlated with different IAP values in patients with the same CVP, the volume of fluid needed might be different.

Immunomodulatory therapies for acute pancreatitis

It is currently difficult for conventional treatments of acute pancreatitis (AP), which primarily consist of anti-inflammatory therapies, to prevent the progression of AP or to improve its outcome. This may be because the occurrence and progression of AP, which involves various inflammatory cells and cytokines, includes a series of complex immune events. Considering the complex immune system alterations during the course of AP, it is necessary to monitor the indicators related to immune cells and inflammatory mediators and to develop more individualized interventions for AP patients using immunomodulatory therapy. This review discusses the recent advances in immunomodulatory therapies. It has been suggested that overactive inflammatory responses should be inhibited and excessive immunosuppression should be avoided in the early stages of AP. The optimal duration of anti-inflammatory therapy may be shorter than previously expected (< 24 h), and appropriate immunostimulatory therapies should be administered during the period from the 3^rd d to the 14^th d in the course of AP. A combination therapy of anti-inflammatory and immune-stimulating drugs would hopefully constitute an alternative to anti-inflammatory drug monotherapy. Additionally, the detection of the genotypes of critical inflammatory mediators may be useful for screening populations of AP patients at high risk of severe infections to enable the administration of early interventions to improve their prognosis.

Heparin-binding protein (HBP/CAP37) - a link to endothelin-1 in endotoxemia-induced pulmonary oedema?

BACKGROUND

Vascular leakage and oedema formation are key components in sepsis. In septic patients, plasma levels of the vasoconstrictive and pro-inflammatory peptide endothelin-1 (ET-1) correlate with mortality. During sepsis, neutrophils release heparin-binding protein (HBP) known to increase vascular permeability and to be a promising biomarker of human sepsis. As disruption of ET-signalling in endotoxemia attenuates formation of oedema, we hypothesized that this effect could be related to decreased levels of HBP. To investigate this, we studied the effects of ET-receptor antagonism on plasma HBP and oedema formation in a porcine model of sepsis. In addition, to further characterize a potential endothelin/HBP interaction, we investigated the effects of graded ET-receptor agonist infusions.

METHODS

Sixteen anesthetized pigs were subjected to 5 h of endotoxemia and were randomized to receive either the ET-receptor antagonist tezosentan or vehicle after 2 h. Haemodynamics, gas-exchange and lung water were monitored. In separate experiments, plasma HBP was measured in eight non-endotoxemic animals exposed to graded infusion of ET-1 or sarafotoxin 6c.

RESULTS

Endotoxemia increased plasma ET-1, plasma HBP, and extravascular lung water. Tezosentan-treatment markedly attenuated plasma HBP and extravascular lung water, and these parameters correlated significantly. Tezosentan decreased pulmonary vascular resistance and increased respiratory compliance. In non-endotoxemic pigs graded ET-1 and sarafotoxin 6c infusions caused a dose-dependent increase in plasma HBP.

CONCLUSIONS

ET-receptor antagonism reduces porcine endotoxin-induced pulmonary oedema and plasma levels of the oedema-promoting protein HBP. Moreover, direct ET-receptor stimulation distinctively increases plasma HBP. Together, these results suggest a novel mechanism by which ET-1 contributes to formation of oedema during experimental sepsis.

Effect of mesenchymal stem cells on renal injury in rats with severe acute pancreatitis

The aim of this study was to preliminarily investigate the effect of bone marrow mesenchymal stem cells (MSCs) on structural change of capillary endothelial barrier and expression variation of aquaporin 1 (AQP1) in kidney at the onset of renal injury caused by severe acute pancreatitis (SAP). Ninety male Sprague-Dawley (SD) rats were divided into the control group, the SAP group in which animals received induction of SAP and the MSCs-treated group in which SAP-induced animals were injected with MSCs. They were further subdivided according to the time point that the animals were killed; 6 h, 12 h and 24 h after the closure of the incision, serum, pancreatic and renal samples were collected, respectively. The level of serum amylase (AMY), creatinine (Cr) and blood urea nitrogen (BUN) were analysed, the change of pancreatic histology was assessed, the structural change of the renal interstitial capillaries was evaluated using the transmission electron microscope (TEM) and the location and expression of AQP1 in kidney were analysed using immunohistochemistry, quantitative polymerase chain reaction and Western blot. The outcomes showed that the level of serum AMY, Cr, BUN elevated, the damage of pancreatic tissue and renal capillary endothelial barrier was aggravated and the expression of AQP1 was reduced significantly after induced pancreatitis. But after treatments with MSCs, the elevation of AMY, Cr and BUN was inhibited, the damage of pancreatic tissue and renal interstitial capillary barrier was alleviated and the down-regulation of AQP1 was reversed. In summary, the MSCs therapy could alleviate renal injury in rats with SAP, the mechanism of which might be related to reduction of the damage to renal interstitial capillary endothelial barrier, and up-expression of AQP1 in kidney.

Effects of different resuscitation fluid on severe acute pancreatitis

AIM: To compare effects of different resuscitation fluid on microcirculation, inflammation, intestinal barrier and clinical results in severe acute pancreatitis (SAP).

METHODS: One hundred and twenty patients with SAP were enrolled at the Pancreatic Disease Institute between January 2007 and March 2010. The patients were randomly treated with normal saline (NS group), combination of normal saline and hydroxyethyl starch (HES) (SH group), combination of normal saline, hydroxyethyl starch and glutamine (SHG group) in resuscitation. The ratio of normal saline to HES in the SH and SHG groups was 3:1. The glutamine (20% glutamine dipeptide, 100 mL/d) was supplemented into the resuscitation liquid in the SHG group. Complications and outcomes including respiratory and abdominal infection, sepsis, abdominal hemorrhage, intra-abdominal hypertension, abdominal compartment syndrome (ACS), renal failure, acute respiratory distress syndrome (ARDS), multiple organ dysfunction syndrome (MODS), operation intervention, length of intensive care unit stay, length of hospital stay, and mortality at 60 d were compared. Moreover, blood oxygen saturation (SpO₂), gastric intramucosal pH value (pHi), intra-abdominal pressure (IAP), inflammation cytokines, urine lactulose/mannitol (L/M) ratio, and serum endotoxin were investigated to evaluate the inflammatory reaction and gut barrier.

RESULTS: Compared to the NS group, patients in the SH and SHG groups accessed the endpoint more quickly (3.9 ± 0.23 d and 4.1 ± 0.21 d vs 5.8 ± 0.25 d, P < 0.05) with less fluid volume (67.26 ± 28.53 mL/kg/d, 61.79 ± 27.61 mL/kg per day vs 85.23 ± 21.27 mL/kg per day, P < 0.05). Compared to the NS group, incidence of renal dysfunction, ARDS, MODS and ACS in the SH and SHG groups was obviously lower. Furthermore, incidence of respiratory and abdominal infection was significantly decreased in the SH and SHG groups, while no significant difference in sepsis was seen. Moreover, less operation time was needed in the SH and SHG group than the NS group, but the difference was not significant. The mortality did not differ significantly among these groups. Blood SpO₂ and gastric mucosal pHi in the SH and SHG groups increased more quickly than in the NS group, while IAP was significantly decreased in the SH and SHG group. Moreover, the serum tumor necrosis factor-α, interleukin-8 and C-reactive protein levels in the SH and SHG groups were obviously lower than in the NS group at each time point. Furthermore, urine L/M ratio and serum endotoxin were significantly lower in the SH group and further decreased in the SHG group.

CONCLUSION: Results indicated that combination of normal saline, HES and glutamine are more efficient in resuscitation of SAP by relieving inflammation and sustaining the intestinal barrier.

Down-regulation of aquaporin 1 in rats with experimental acute necrotizing pancreatitis

OBJECTIVES

The objectives of this study were to investigate the expression of aquaporin 1 in capillary endothelial cells of rats with experimental acute necrotizing pancreatitis (ANP) and to explore its pathogenic role in capillary leak.

METHODS

Sixty-four male Sprague-Dawley rats were randomly divided into control (n = 32) and ANP groups (n = 32). Eight rats in each group were killed at 3, 6, 12, and 18 hours after induction of experimental models. Quantity of ascites and levels of serum amylases were measured. Capillary permeability in pancreas, lung, and intestinal tissue was detected by Evans blue extravasation method. Aquaporin 1 expression in pancreas, lung, and intestinal tissue was detected by real-time polymerase chain reaction, immunohistochemical staining, and Western blot.

RESULTS

Serum amylase level was significantly higher in ANP group than in controls (P < 0.05). Evans blue concentration in tissues in the ANP group was significantly higher than that in controls (P < 0.05). Aquaporin 1 mRNA and protein expressions in tissues were significantly less in the ANP group than in the controls (P < 0.05).

CONCLUSIONS

The expression of aquaporin 1 was down-regulated in the pancreas, lung, and intestinal tissue of ANP rats, which could play an important role in the pathogenesis of capillary leak syndrome.

Protective effects of edaravone against acute necrotizing pancreatitis in rats

AIM: To investigate whether edaravone has protective effects against acute necrotizing pancreatitis (ANP) in rats and to explore the possible mechanisms involved.

METHODS: Ninety male Spraque-Dawley rats were randomly and equally divided into sham operation group, ANP group and edaravone treatment group (EDA group). ANP was induced in rats of the ANP and EDA groups by retrograde injection of 1.5% deoxycholate. The EDA group was injected with edaravone (6 mg/kg) via the tail vein immediately after ANP induction. The rats were sacrificed 6, 12, and 24 h after the operation. Pathological changes in the pancreas were observed and graded. Serum levels of amylase, tumor necrosis factor-alpha (TNF-α), endothelin-1 (ET-1) and soluble intercellular adhesion molecule-1 (sICAM-1), as well as malonic dialdehyde (MDA) content and superoxide dismutase (T-SOD) activity in pancreatic tissue were measured.

RESULTS: Compared to the sham operation group, pancreatic pathological scores, serum levels of amylase, TNF-α, ET-1 and sICAM-1, and the contents of MDA in pancreatic tissue were significantly increased, and T-SOD activity in pancreatic tissue was significantly decreased in the ANP group. Compared to the ANP group, pancreatic pathological scores, serum levels of TNF-α (6 h: 109.6 ng/L ± 49.0 ng/L vs 190.2 ng/L ± 46.6 ng/L, 12 h: 405.4 ng/L ± 116.3 ng/L vs 559.7 ng/L ± 203.9 ng/L, 24 h: 415.4 ng/L ± 164.6 ng/L vs 648.7 ng/L ± 222.1 ng/L, all P < 0.05), ET-1 (6 h: 45.6 ng/L ± 13.5 ng/L vs 66.0 ng/L ± 16.0 ng/L, 12 h: 83.5 ng/L ± 15.4 ng/L vs 96.8 ng/L ± 23.0 ng/L, 24 h: 85.1 ng/L ± 25.8 ng/L vs 103.9 ng/L ± 28.9 ng/L, all P < 0.05), and sICAM-1 (6 h: 0.58 ng/L ± 0.13 ng/L vs 0.78 ng/L ± 0.14 ng/L, 12 h: 0.78 ng/L ± 0.10 ng/L vs 0.94 ng/L ± 0.12 ng/L, 24 h: 0.96 ng/L ± 0.16 ng/L vs 1.24 ng/L ± 0.30 ng/L, all P < 0.05), and the contents of MDA in pancreatic tissue (6 h: 4.22 nmol/mgprot ± 0.40 nmol/mgprot vs 8.79 nmol/mgprot ± 0.80 nmol/mgprot, 12 h: 5.90 nmol/mgprot ± 0.51 nmol/mgprot vs 12.30 nmol/mgprot ± 1.02 nmol/mgprot, 24 h: 9.10 nmol/mgprot ± 0.84 nmol/mgprot vs 17.88 nmol/mgprot ± 1.43 nmol/mgprot, all P < 0.05) were reduced, and T-SOD activity was increased (6 h: 88.6 U/mgprot ± 7.1 U/mgprot vs 68.8 U/mgprot ± 10.5 U/mgprot, 12 h: 77.6 U/mgprot ± 6.8 U/mgprot vs 46.0 U/mgprot ± 8.9 U/mgprot, 24 h: 45.5 U/mgprot± 5.3 U/mgprot vs 27.8 U/mgprot ± 4.3 U/mgprot, all P < 0.05) in the EDA group. No significant differences were observed in serum levels of amylase between the ANP and EDA groups.

CONCLUSION: Edaravone can eliminate the excessive generation of oxygen free radicals, down-regulate the expression of inflammatory cytokines, and reduce tissue injury in rats with ANP.

Regulation of blood pressure and salt homeostasis by endothelin

Endothelin (ET) peptides and their receptors are intimately involved in the physiological control of systemic blood pressure and body Na homeostasis, exerting these effects through alterations in a host of circulating and local factors. Hormonal systems affected by ET include natriuretic peptides, aldosterone, catecholamines, and angiotensin. ET also directly regulates cardiac output, central and peripheral nervous system activity, renal Na and water excretion, systemic vascular resistance, and venous capacitance. ET regulation of these systems is often complex, sometimes involving opposing actions depending on which receptor isoform is activated, which cells are affected, and what other prevailing factors exist. A detailed understanding of this system is important; disordered regulation of the ET system is strongly associated with hypertension and dysregulated extracellular fluid volume homeostasis. In addition, ET receptor antagonists are being increasingly used for the treatment of a variety of diseases; while demonstrating benefit, these agents also have adverse effects on fluid retention that may substantially limit their clinical utility. This review provides a detailed analysis of how the ET system is involved in the control of blood pressure and Na homeostasis, focusing primarily on physiological regulation with some discussion of the role of the ET system in hypertension.

Differential effects of endothelins on histological and ultrastructural changes and trypsinogen activation in the secretagogue-induced acute pancreatitis in rats

The role of endothelins in acute pancreatitis remains obscure. To assess the effects of endothelins (ETs) in early (4 h) caerulein-induced acute pancreatitis (AP) in rats, ET-1, ET-2 and ET-3 (0.5 or 1.0 nmol/kg) were applied twice with i.p. caerulein (2×40 μg/kg) at 1h interval. Histological and ultrastructural examinations of pancreases and the assay of trypsinogen activation in whole homogenate were performed. All ETs, especially ET-1 at the higher dose, decreased inflammatory cell infiltration despite an increase in the edema score. The vacuolization and necrosis of acinar cells were slightly increased after the lower dose of ET-1 and ET-2. Ultrastructural changes were generally improved after the higher dose of ETs. Trypsinogen activation increased from 4.8±1.3% in control to 18.4±3.8% in AP (p<0.01). It was attenuated to 6.4±1.3% (p<0.01) by the higher dose of ET-1 and to 8.8±1.5% (p<0.05) by the lower dose of ET-3. In summary, ETs, especially ET-1 at the higher dose, were found to have some beneficial effects on morphological changes and trypsinogen activation in the pancreas in early caerulein-induced AP.

Effect of platelet-activating factor antagonist WEB 2086 on microcirculatory disorders in acute experimental pancreatitis of graded severity

OBJECTIVES

Platelet-activating factor (PAF) is an important mediator of inflammation and postulated to be involved in the pathogenesis of acute pancreatitis. In this study, we evaluated the therapeutic effect of PAF antagonist WEB 2086 in acute experimental pancreatitis of graded severity in rats.

METHODS

According to a block design, 64 animals were randomly allocated to 8 groups. Severe necrotizing pancreatitis was induced by intraductal infusion of taurocholic acid (4%, 0.4 mL), and the combination of glycodeoxycholic acid (10 mmol/L, 1.0 mL/kg, intraductal infusion) and cerulein (5 microg/kg per hour, intravenous) was applied to induce intermediate pancreatitis, or cerulein alone (5 microg/kg per hour, intravenous) to establish edematous pancreatitis. WEB 2086 was given 15 minutes after beginning the induction of pancreatitis. Pancreatic microcirculation was analyzed in vivo with an epiluminescent microscope. Histopathology was evaluated by a validated score. Trypsinogen-activating peptide and serum amylase were analyzed sequentially.

RESULTS

WEB 2086 had no significant influence on the breakdown of microcirculation, leukocyte adherence, histopathological damage, and amylase levels in severe necrotizing pancreatitis, intermediate pancreatitis, and edematous pancreatitis. Only in intermediate pancreatitis was there a significant reduction of trypsinogen-activating peptide levels.

CONCLUSIONS

In our study, PAF antagonist WEB 2086 had no beneficial effect on microcirculation in acute experimental pancreatitis.

Fluid resuscitation in acute pancreatitis

Acute pancreatitis is a common inflammatory disorder of the pancreas resulting in considerable morbidity and a mortality rate of approximately 5%. Although there are no pharmacologic treatments known to improve important outcomes, aggressive intravenous fluid resuscitation generally is recommended in all patients. However, few human investigations have been performed and several important questions have not been answered. For example, what is the optimal resuscitative fluid? Is there a role for colloid solutions? To what clinical marker should resuscitation be targeted? When is the best time to start such fluids and in which group of patients? This review describes the microcirculation of the pancreas and the pathophysiologic alterations caused by acute pancreatitis. Previous animal experiments are described, as are the limited human studies specifically addressing fluid resuscitation. Finally, current recommendations and goals for further investigation are highlighted. It is our hope that this review will stimulate interest in this often overlooked subject and lead to carefully designed human clinical trials using varying fluid solutions and rates, with an emphasis on patient monitoring and safety, in the near future.

Pathophysiological role of platelets and platelet system in acute pancreatitis

The most successful approach for restoring normal long-term glucose homeostasis in type I diabetes mellitus is whole-organ pancreas transplantation. Graft pancreatitis is observed in up to 20% of patients and may lead to loss of the transplanted organ. Several pathophysiological events have been implicated in this form of pancreatitis. The most important cause of early graft pancreatitis is ischemia/reperfusion (I/R)-related disturbance of microvascular perfusion with subsequent hypoxic tissue damage. Recently, considerable evidence accumulated that, among a variety of other pathophysiological events, the activation of platelets can contribute to I/R injury in the course of acute pancreatitis experimentally and clinically. This review summarizes the events affecting platelet function and, therefore, pancreatic microcirculation leading to acute pancreatitis. Therapeutic approaches and own results are presented.

The protecting effects and mechanisms of Baicalin and Octreotide on heart injury in rats with SAP

Purpose. To observe the protecting effects and mechanisms of Baicalin and Octreotide on heart injury in rats with severe acute pancreatitis (SAP). Methods. The SAP rat models were randomly divided into the model group, Baicalin-treated group, Octreotide treated group, and sham operation group. The contents of some inflammatory indexes in blood were determined. The rat mortality, pathological changes of heart, the changes of NF-κB, P-Selectin, Bax, Bcl-2, and Caspase-3 protein expression levels as well as apoptotic index were observed in all groups, respectively, at 3 hours, 6 hours, and 12 hours after operation. Results. The survival rate of model group was less than treated groups at 12 hours, difference was significant. The contents of some inflammatory indexes of the treated groups were lower than those of the model group to various degrees at different time points. The pathological myocardial changes under light microscope were milder in treated groups than in model group. The changes of NF-κB, P-Selectin, Bax, Bcl-2, and Caspase-3 protein expression levels in all groups were different. There was only a case of myocardial cell apoptosis in an Octreotide-treated group at 6 hours. Conclusion. Baicalin and Octreotide have protecting effects on heart injury of rats with SAP.

Endothelin-1 reduces mesenteric microvascular hydraulic permeability via cyclic AMP and protein kinase A signal transduction

We have previously shown that endothelin-1 (ET-1) decreases microvascular hydraulic permeability. In this study, we tested the hypothesis that ET-1 exerts its permeability-decreasing effect through cAMP, cGMP, and protein kinase A (PKA) by determining the effect of ET-1 on venular fluid leak during inhibition of cAMP synthesis, inhibition of cGMP degredation, and inhibition of PKA. Rat mesenteric venules were cannulated to measure hydraulic permeability, L(p) (units x 10(-7)cm/(s cmH(2)O)). L(p) was measured during continuous perfusion of 80 pM ET-1 and either (1) an inhibitor of cAMP synthesis (10 microM 2',5'ddA), (2) an inhibitor of cGMP degradation (100 microM Zaprinast), or (3) an inhibitor of PKA (10 microM H-89). Inhibition of cAMP synthesis blocked the permeability decreasing effects of ET-1. The peak L(p) of the cAMP inhibitor alone and with ET-1 was 4.11+/-0.53 and 3.86+/-0.19, respectively (p=0.36, n=6). Inhibition of cGMP degradation did not block the permeability decreasing effects of ET-1. The peak L(p) during inhibition of cGMP degradation alone and with ET-1 was 2.26+/-0.15 and 1.44+/-0.09, respectively (p<0.001, n=6). Inhibition of PKA activation blocked the permeability decreasing effects of ET-1. The peak L(p) of the PKA inhibitor alone and with ET-1 was 2.70+/-0.15 and 2.59+/-0.15, respectively (p=0.38, n=6). The data support the notion that the signal transduction mechanism of ET-1 with regard to decreasing microvascular fluid leak involves cAMP production and PKA activation, but not cGMP degradation. Further understanding of intracellular mechanisms that control microvascular fluid leak could lead to the development of a pharmacologic therapy to control third space fluid loss in severely injured or septic patients.

Pathophysiological role of platelets in acute experimental pancreatitis: influence of endothelin A receptor blockade

The potential pathophysiological role of platelet-endothelium interactions was investigated during ischemia/reperfusion (I/R), and the effect of a selective endothelin(A) receptor antagonist (ET(A)-RA) was evaluated in an acute pancreatitis model. Acute pancreatitis was induced by warm ischemia (60 min) in Wistar rats, and its effects with and without antagonist treatment were investigated. Equivalent sham-operated animals were also studied. Microcirculatory changes were assessed by in vivo microscopy, and serum levels for lipase/amylase and histological specimens were investigated. Capillary constriction to 83.7 +/- 6.7% of sham-operated diameters was observed after 60 min of ischemia. A capillary density of 56.8 +/- 9.3% of the sham-operated group (396.3 +/- 15.8 mm(-1)) was measured after reperfusion. Stagnant leukocytes (329.5 +/- 30.4%) and platelets (337.5 +/- 32.3%) increased in postcapillary venules (P < 0.05). Administration of the ET(A)-RA significantly reduced I/R injury. Capillary diameters were maintained (101.4 +/- 4.5%), and capillary density was improved to 73.3 +/- 7.6% of sham-operated animals (P < 0.05). Stagnant leukocytes (152.3 +/- 10.6%) and platelets (207.1 +/- 19.8%) in sinusoids and postcapillary venules were reduced (P < 0.05). The extent of acute pancreatitis was reduced in the therapy group as indicated by serum lipase/amylase values and histological tissue damage (P < 0.05). Thus, ET(A)-RA therapy was effective in reducing I/R-induced pancreatitis in this experimental model.

Substance P mediates cerulein-induced pancreatic microcirculatory dysfunction in mice

OBJECTIVES

The present study was conducted to examine the contribution of substance P to the pancreatic microcirculatory dysfunction during acute pancreatitis.

METHODS

Pancreatitis was elicited by up to 6 hourly injections of cerulein (50 microg/kg IP) in male C57Bl/6 mice. At 0, 1, 3, and 6 hours after cerulein treatment, the pancreatic microvasculature in anesthetized mice was studied using established high-resolution in vivo microscopic methods.

RESULTS

Treatment of mice with cerulein for 6 hours caused a 30% decrease in capillary perfusion and the diameter of the capillaries and an increase in microvascular permeability (20%) and interstitial space (30-fold). The administration of the substance P receptor antagonist (D-Arg1, D-Pro2, D-Trp7,9, Leu11) (2 mg/kg IP) minimized the pancreatic microcirculatory dysfunction 3 hours after cerulein treatment. The superfusion of substance P for 0.5 hours decreased the diameter (by 22%) and increased microvascular permeability (by 23%) along with interstitial space (22-fold increase). Blockade of substance P receptor attenuated substance P-induced pancreatic microcirculatory dysfunction.

CONCLUSIONS

These results suggest that substance P mediates pancreatic microcirculatory dysfunction during the development of acute pancreatitis.

Endothelin-1 receptor antagonist (LU-135252) improves the microcirculation and course of TNBS colitis in rats

The role of microcirculation in the pathogenesis and course of chronic inflammatory bowel disease is still unclear. The aim of this study was the evaluation of the role of microcirculation in colitis activity in the rat TNBS (trinitrobenzenesulfonic acid) colitis model using endothelin-1 and a selective endothelin-1 receptor antagonist (LU-135252). Target parameters were capillary blood flow, functional capillary density, vascular permeability, and leukocyte sticking as well as recording of hematocrit, weight course, diuresis, stool quality, and degree of inflammation using a histological colitis score. The acute phase of TNBS colitis is characterized by an extensive disturbance of microcirculation (a significant decrease in capillary blood flow and capillary density and a significant increase in capillary permeability and leukocyte sticking in the mucosa). There is also a significant increase in hematocrit and a significant decrease in diuresis and weight. An exogenous supply of endothelin-1 does not lead to an aggravation of these disorders because of a possible blockage of the endothelin-1 receptors by endogenous endothelin-1 in this florid inflammatory phase. Applying the selective endothelin-1 receptor A antagonist LU-135252 leads to a significant improvement of all microcirculatory parameters and clinical findings compared to the untreated colitis group. Direct improvement of capillary blood flow in the early phase of colitis leads to reduced colitis activity, which underscores the pathogenetic role of the microcirculation in the progression of colitis.

Disturbances of the microcirculation in acute pancreatitis

BACKGROUND

Severe acute pancreatitis is characterized by pancreatic necrosis, resulting in local and systemic inflammation. Pancreatitis affects both the systemic and pancreatic vasculature. This review focuses on the underlying processes involved in the changes of microvascular anatomy following acute pancreatitis.

METHODS

A Medline/PubMed search (January 1966 to December 2005) with manual cross-referencing was conducted. All relevant articles investigating the pancreatic microcirculatory anatomy and the effect of pancreatitis on the microcirculation were included.

RESULTS

The pancreas is susceptible to ischaemic insult, which can exacerbate acute pancreatitis. There is also increasing evidence of pancreatic and systemic microvascular disturbances in the pathogenesis of pancreatitis, including vasoconstriction, shunting, inadequate perfusion, and increased blood viscosity and coagulation. These processes may be caused or exacerbated by ischaemia-reperfusion injury and the development of oxygen-derived free radicals.

CONCLUSION

Acute pancreatitis impairs the pancreatic and systemic microcirculation, which is a key pathological process in the development of severe necrotizing disease.

Hemoconcentration is a poor predictor of severity in acute pancreatitis

AIM

To determine whether the hematocrit (Hct) at admission or at 24 h after admission was associated with severe acute pancreatitis (AP), organ failure (OF), and pancreatic necrosis.

METHODS

A total of 336 consecutive patients with a first AP episode were studied. Etiology, Hct values at admission and at 24 h, development of severe AP according to Atlanta's criteria, pancreatic necrosis, OF and mortality were recorded. Hemoconcentration was defined as Hct level >44% for males and >40% for females. The t-test and chi2 test were used to assess the association of hemoconcentration to the severity, necrosis and OF. Diagnostic accuracy was also determined.

RESULTS

Biliary disease was the most frequent etiology (n = 148). Mean Hct levels at admission were 41+/-6% for females and 46+/-7% for males (P<0.01). Seventy-eight (23%) patients had severe AP, and OF developed in 45 (13%) patients. According to contrast-enhanced computed tomography scan, 36% (54/150) patients showed pancreatic necrosis. Hct levels were elevated in 58% (55/96) and 61% (33/54) patients with interstitial and necrotizing pancreatitis, respectively. Neither Hct levels at admission nor hemoconcentration at 24 h were associated with the severity, necrosis or OF. Sensitivity, specificity and positive predictive values for both determinations were very low; and negative predictive values were between 61% and 86%, being the highest value for OF.

CONCLUSION

Hct is not a useful marker to predict a worse outcome in acute pancreatitis. In spite of the high negative predictive value of hemoconcentration, the prognosis gain is limited due to an already high incidence of mild disease.

Selective COX-2 inhibition reduces leukocyte sticking and improves the microcirculation in TNBS colitis

The role of cyclooxygenase-2 inhibitors in the course of experimental colitis is controversially discussed. The aim of this study was to evaluate leukocyte-endothelium interaction and colitis activity after applying the selective cyclooxygenase-2 inhibitor NS-398 in a rat trinitrobenzene sulfonic acid (TNBS) colitis model. The acute phase of TNBS colitis is characterized by a significant reduction of capillary blood flow, capillary density, diuresis, and weight and a significant increase in capillary permeability, leukocyte sticking, and hematocrit. Applying the selective cyclooxygenase-2 inhibitor NS-398 leads to a significant improvement of all microcirculatory parameters and clinical findings compared to the (untreated) colitis group. There are no histopathological differences between the individual colitis groups. Acute colitis is characterized by an extensive disturbance of microcirculation together with signs of systemic inflammatory response syndrome. These alterations are significantly improved by inhibiting cyclooxygenase-2. The results support the described correlation between cyclooxygenase activation and leukocyte-endothelium interaction. Moreover, they underscore the postulated relation between leukocyte-endothelium interaction and capillary blood flow.

Changes of endothelin levels and therapeutic effects of Danshen in lung injury induced by severe acute pancreatitis in rats

AIM: To explore the changes of endothelin (ET) levels, in serum and lung, and the therapeutic effects of labiatae on severe acute pancreatitis (SAP) with lung injury in rats.

METHODS: A total of 60 Wistar rats were randomized into sham operation group (J), model group (F), and Danshen treatment group (D). The model of SAP was established by retrograde injection of 50 g/L sodium taurocholate into the pancreatic and biliary duct. The rats in group D were intraperitoneally injected with Danshen (5 mL/kg) 1 d before and 10 min after modeling. The levels of serum and pulmonary endothelin-1 were evaluated 24 and 48 h after modeling. Meanwhile, the changes of pulmonary histopathology and lung index were observed.

RESULTS: In comparison with those in group J, the pulmonary histopathological changes in group F were significantly aggravated, and the level of serum endothelin-1 and lung index were increased markedly 24 and 48 h after modeling (endothelin-1: 75.8 ± 4.8, 70.4 ± 4.8 ng/L vs 32.0 ± 6.9, 30.3 ± 4.8 ng/L, P < 0.01; lung index: 0.62 ± 0.06, 0.73 ± 0.07 vs0.41 ± 0.08, 0.41 ± 0.07, P < 0.01). Meanwhile, the expression of pulmonary endothelin-1 (using optical density) was elevated (F group: 0.48 ± 0.09, 0.61 ± 0.10; J group: 0.05 ± 0.01, 0.05 ± 0.01, P < 0.01; for 24 and 48 h respectively). Compared with those in group F, the pulmonary pathological changes in group D were notably alleviated, and the levels of serum endothelin-1 and lung index were notably dropped 24 and 48 h after modeling (60.2 ± 7.3 ng/L, 0.52 ± 0.06, P < 0.05; 57.9 ± 5.4 ng/L, 0.58 ± 0.06, P < 0.01), and the expression of pulmonary endothelin-1 was also decreased significantly (0.23 ± 0.10, 0.36 ± 0.09, for 24 and 48 h, respectively, P < 0.01 vs group F). The expression of pulmonary endothelin-1 was correlated with the lung index both at 24 and 48 h (r = 0.736, P < 0.01; r = 0.828, P < 0.01).

CONCLUSION: Endothelin-1 plays an important role in lung injury induced by SAP. Danshen can protect lung tissues from such injury.

LHRH-PE40-Induced Vascular Leak Syndrome

AIM

This study was designed to study the toxicity of LHRH-PE40, a recombinant DNA-derived protein composed of the decapeptide known as luteinizing hormone-releasing hormone and the translocation and catalytic domains of pseudomonas exotoxin A.

METHOD

Single-dose and repeat-dose toxicity of intravenous injection of LHRH-PE40 was studied by clinical signs, hematology, blood chemistry and histopathology, and lung permeability to Evans blue dye. Additional study was performed to find the relationship between dexamethasone pretreatment and vascular leak syndromes.

RESULTS

Dyspnea, increased hemocrit, low serum total protein, lung edema, and high lung permeability were found on rats treated with single or repeated doses of LHRH-PE40. Dexamethasone pretreatment before LHRH-PE40 administration partly lowered morbidity of rats.

CONCLUSION

LHRH-PE40-induced vascular leak syndrome was the chief cause of rats' death. Dexamethasone pretreatment partly reduced the frequency of vascular leak syndrome. Hypotheses about vascular leak syndromes were also formed by reviewing recent literature.

N/A

N/A

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

AIM: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.

Improvement of postischemic hepatic microcirculation after endothelinA receptor blockade--endothelin antagonism influences platelet-endothelium interactions

Endothelin (ET) contributes to disturbances of hepatic microcirculation after ischemia/reperfusion (I/R) by causing vasoconstriction and enhancing leukocyte- and platelet-endothelium interactions. The aim of this study was to investigate a possible protective role of a selective endothelin(A) receptor antagonist (ET(A)-RA) in this setting. In a rat model, warm ischemia of the left lateral liver lobe was induced for 90 minutes under intraperitoneal anesthesia with xylazine and ketamine. Groups of rats consisted of sham-operated (SO, n=14), untreated ischemia (n=14), and treatment with BSF208075 (5 mg/kg body weight IV, n=14). The effect of the ET(A)-RA on I/R was assessed by in vivo microscopy 20 to 90 minutes after reperfusion; by measurement of local tissue Po(2), serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and glutathione S-transferase alpha levels, and by histologic investigation. In the untreated group, sinusoidal constriction to 69.4+/-6.7% of diameters of SO rats was observed, leading to a significant decrease in perfusion rate (74.3+/-2.1% of SO) and liver tissue Po(2) (43.5+/-3.2% of SO) (P < 0.05). In addition, we found an increased percentage of stagnant leukocytes (142.9+/-11.9%) and platelets (450.1+/-62.3%) in sinusoids and in postsinusoidal venules (P < 0.05). Hepatocellular damage (AST and ALT increase to 1330+/-157 U/L and 750+/-125 U/L respectively; previously, 27.1+/-3.5 U/L and 28.5+/-3.6 U/L) was detected 6 hours after reperfusion (P < 0.05). Administration of the ET(A)-RA before reperfusion significantly reduced I/R injury. Sinusoidal diameters were maintained (108.5+/-6.6%), and perfusion rate (93.1+/-1.8%) and tissue Po(2) (95.3+/-5.7%) were significantly increased (P < 0.05). According to reduced leukocyte-endothelium interactions after therapy, both platelet rolling and adhesion were significantly reduced (P < 0.05). The number of stagnant platelets in sinusoids was 199.5+/-12.3% of 50 (P < 0.05). After treatment, hepatocellular damage was decreased (AST and ALT levels after 6 hours of reperfusion: 513+/-106 U/L and 309+/-84 U/L, respectively; P < 0.05), and histologic changes were reduced in the long term. Our results provide evidence that the new therapeutic approach with an ET(A)-RA is effective in reducing hepatic I/R injury. In addition to reduced leukocyte-endothelium interactions, the number of stagnant and rolling platelets in sinusoids and venules was significantly reduced. The reduction in microcirculatory damages is responsible for better organ outcome.

N/A

N/A

Dynamic intravital fluorescence microscopy--a novel method for the assessment of microvascular permeability in acute pancreatitis

Edema formation is the first manifestation of acute pancreatitis. Microcirculatory derangements like leukocyte-endothelial cell interaction and perfusion failure result in enhancement of microvascular permeability to large molecules playing a pivotal role in the progression of the acutely altered pancreatic tissue. Due to the lack of suitable methods the crucial mechanisms of enhanced permeability in vivo are not very well investigated. Sprague-Dawley rats were randomly assigned to three groups: (a) sham operated animals with normal pancreas, (b) the pancreatitis group induced by 60 min temporary occlusion of the arterial supply followed by reperfusion and (c) the histamine group in which the pancreas was superfused with 10(-5)M histamine. The pharmacokinetics of tetramethylrhodamine-labelled BSA in the intravital microscopic images of a capillary network of the pancreas were densitometrically quantified over 20 min. From these data the effective microvascular permeability was calculated taking also into account morphology of microvessels, elimination rate of the tracer from the intravascular space and capillary microhematocrit. In addition macromolecular leakage of gold-labelled BSA was investigated by electron microscopy. Microvascular permeability was 0.10 +/- 0.02 x 10(-7) cm/s, 0.49 +/- 0.04 x 10(-7) cm/s and 1.21 +/- 0.29 x 10(-7) cm/s for control, ischemia and histamine group, respectively (P < 0.05 ischemia, histamine vs. control and ischemia vs. histamine). Electron microscopy revealed albumin extravasation in the last two groups. We established a technique allowing to quantify microvascular permeability in pancreatic tissue by dynamic intravital microscopy being independent of the investigator. This technique enabling accurate pathophysiologic characterisation in terms of edema formation can form the basis for evaluating in the future novel treatment strategies directed against acute pancreatitis.

Endothelin-1 decreases microvessel permeability after endothelial activation

BACKGROUND

Endothelin-1 (ET-1) is a potent vasoconstrictor that is released during shock and sepsis. We hypothesized that ET-1 plays a role in the modulation of the elevated microvascular permeability state of the activated endothelium.

METHODS

Hydraulic permeability (Lp) was measured using the modified Landis micro-occlusion technique. The effect of different ET-1 doses on Lp was determined by obtaining paired measures of Lp at baseline and after the vessels were perfused with ET-1 at doses of 2.0 pg/mL (n = 6), 20 pg/mL (n = 6), 200 pg/mL (n = 6), or 2,000 pg/mL (n = 6). To evaluate the effects of ET-1 in the activated endothelium, additional vessels were perfused with either 10 micromol/L adenosine triphosphate (ATP) (n = 6) or 1 nmol/L bradykinin (n = 6). The vessels were then perfused with 200 pg/mL ET-1 followed by the final L determination.

RESULTS

ET-1 significantly decreased Lp at doses of 20 pg/mL (p = 0.03), 200 pg/mL (p = 0.03), and 2,000 pg/mL (p = 0.01). Endothelial activation with ATP and bradykinin increased Lp to 4.21 +/- 0.39 (p < 0.0001) and 2.72 +/- 0.24 (p = 0.001), respectively. ET-1 significantly decreased the Lp to 1.99 +/- 0.48 after activation with ATP (p = 0.004). ET-1 also decreased the Lp to 1.10 +/- 0.19 after activation with bradykinin (p = 0.001). Units for Lp are x10(-7) cm x s(-1) x cm H2O(-1).

CONCLUSION

In this model, ET-1 attenuated the increase in microvascular permeability that can be seen in inflamed vessels. In addition to its vasopressor function, ET-1 may be of benefit in pathophysiologic states by decreasing third-space fluid loss. This receptor-mediated function of ET-1 may be amenable to pharmacologic manipulation.

Endothelin receptor antagonists are not beneficial in the therapy of acute experimental pancreatitis

BACKGROUND AND AIM

Due to increased capillary permeability and the early appearance of vasoactive and toxic agents, patients suffering from necrotizing pancreatitis frequently develop a systemic inflammatory response syndrome (SIRS). Endothelin, a potent vasoconstrictor, is thought to play a major role in these changes via the regulation of microcirculation. An improved outcome of acute experimental necrotizing pancreatitis by blocking the endothelin receptors ETA and ETB, either selectively (only ETA) or unselectively (ETA and ETB), has been suggested. The aim of this study was to investigate further the beneficial effects of new, highly potent endothelin-receptor (ET-R) antagonists in acute experimental pancreatitis.

METHODS

The influence of the selective ET-RA antagonist BSF208075 (1 mg/kg) on mortality was studied in three severity groups of acute necrotizing pancreatitis (retrograde injection of 4%, 5% and 6% of sodium taurocholate into the main pancreatic duct). The effects of the selective ET-RA antagonists LU135252 (LU13) and BSF208075 (BSF20) and of the unselective endothelin receptor (ET-R(A/B)) antagonist BSF420627 (BSF42) were additionally analyzed in 4% taurocholate-induced necrotizing pancreatitis. Furthermore, the significance of variable doses of the endothelin receptor antagonist LU13 (1 mg/kg, 3 mg/kg and 100 mg/kg) was determined in a 4% sodium taurocholate model and in a cerulein pancreatitis model.

RESULTS

Prophylactic ET-R antagonism increased the mortality rate in the 4% sodium taurocholate-induced pancreatitis. No reduction in pancreatic damage after induction of taurocholate pancreatitis was found by ET-R blockage. Application of ET-R antagonists had no beneficial influence in ascites development. However, administration of LU13 (100 mg/kg) resulted in a non-significant increase in pancreatic oedema, whereas peritoneal necrosis was not affected.

CONCLUSION

The selective and unselective ET-R antagonists BSF20, BSF42 and LU13 failed to improve survival and pancreatic damage during acute experimental pancreatitis. Therefore, previously reported beneficial effects of ET-R antagonists in experimental acute pancreatitis have to be critically evaluated before conclusions for further clinical development are made.

The endothelin-1 receptor antagonists ameliorate histology and ultrastructural alterations in the pancreas and decrease trypsinogen activation in severe taurocholate pancreatitis in rats

The role of potent vasoconstrictor endothelin-1 (ET-1) in acute pancreatitis (AP) remains controversial. The aim was to compare the effect of nonselective ET RA/B (LU-302872) and selective ET RA (LU-302146) antagonists on pancreatic histology, ultrastructure and trypsinogen activation in severe taurocholate AP in rats. Male Wistar rats with AP were treated with an intraperitoneous injection of 1, 5 and 10 mg/kg of body weight of each antagonist at 0, 6, 12 and 18 h after taurocholate administration. After 24 h, the samples of pancreases were taken for histological and ultrastructural examinations and for assessment of trypsinogen activation. Both antagonists, at all investigated doses, decreased the damage to the acinar cells detected in the light microscope and ultrastructurally. Trypsinogen activation increased to 29.7 +/- 3.9% in the AP untreated in comparison to the control group [12.7 +/- 1.4% (P<0.001)]. This increase was attenuated to 13.8 +/- 2.2% in AP treated with a high dose of the nonselective antagonist and to 8.4 +/- 1.7% with low dose of selective antagonist. The obtained results indicate that ET-1 could participate in the damage to the pancreas during AP. Both antagonists of ET-1 receptors exerted a similar beneficial effect on the morphological changes of the pancreas in AP. One of the probable mechanism could be the attenuation of trypsinogen activation.

Endothelin(A) receptor blockade reduces ischemia/reperfusion injury in pig pancreas transplantation

OBJECTIVE

The effect of prophylactic administration of a selective endothelin(A) receptor antagonist (ET(A)-RA) on ischemia/reperfusion injury in an experimental model of graft pancreatitis after pancreas transplantation was evaluated.

SUMMARY BACKGROUND DATA

It is well established that endothelin-1 (ET-1), a powerful vasoconstrictor, plays an important role in the development of pancreatitis. Recent studies have shown a beneficial effect of endothelin receptor antagonists in the therapy for experimental pancreatitis.

METHODS

Relevant ischemia/reperfusion injury was induced in pig pancreas transplants after 6 hours hypothermic preservation in University of Wisconsin solution. The recipients were randomized into 2 groups: control pigs received isotonic saline and the treated group received the selective ET(A)-RA BSF 208075 at the beginning of reperfusion. On postoperative days 2 and 5, animals were relaparotomized to obtain tissue specimens. Blood monitoring included lipase, amylase, C-reactive protein, trypsinogen-activation peptide, thiobarbituric acid-reacting substances, and ET-1. Partial oxygen tension (p(ti)O(2)) was measured by a Clarke-type electrode and blood flow by laser doppler. A semiquantitative score index was used for assessment of histologic injury and for immunohistochemical analysis of ET-1 and ET(A) receptor expression. Tissue mRNA levels of prepro ET-1, ET(A) receptor, pro-interleukin (IL)-6, and pro-IL-1beta were quantified using TaqMan real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Prophylactic treatment with ET(A)-RA significantly reduced the severity of graft pancreatitis evidenced by C-reactive protein. The finding of transient capillary perfusion at the beginning of reperfusion supports the application of the ET(A)-RA during this period. The dramatic increase of plasma ET-1 in the therapy group is a clear evidence of effective receptor blockade. Mean trypsinogen-activation peptide levels from the portal venous effluent, but not mean systemic plasma TAP values were significantly lower in the treated group. Analysis of p(ti)O(2) and blood flow revealed a significant improvement of capillary perfusion and blood flow in the treated group and was associated with relevant reduction of tissue injury. Intrapancreatic ET-1 and IL-6 mRNA expression and ET-1 protein levels were significantly lower in the therapy group as compared with the control group. In contrast, ET(A) mRNA showed a marked up-regulation by ET(A) receptor blockade.

CONCLUSION

Application of a ET(A)-RA reduces ischemia/reperfusion induced graft pancreatitis in a pig transplantation model by improving microcirculation and reducing tissue injury.

Further evidence for endothelin as an important mediator of pancreatic and intestinal ischemia in severe acute pancreatitis

INTRODUCTION

Severe acute pancreatitis is occasionally associated with pancreatic and intestinal necrosis. Mesenteric vasoconstriction is one of the most probable types of pathogenesis of these complications.

AIM

To investigate the involvement of endothelin-1 (ET-1), a potent vasoconstrictor.

METHODOLOGY AND RESULTS

Plasma ET-1 concentrations were extremely high in patients with pancreatic and/or diffuse intestinal necrosis. ET-1 mRNA was demonstrated in the rat pancreas, and the production of ET-1 protein by human umbilical vein endothelial cells was enhanced by tumor necrosis factor-alpha, thrombin, and protease-activated receptor-2-activating peptide. Administration of ET-1 in vivo induced mesenteric arterial spasm and decreased pancreatic and intestinal blood flow.

CONCLUSION

These results suggest the following: ET-1 is produced in and around the pancreas, mainly by endothelial cells, in severe acute pancreatitis; in the inflammatory setting, cytokines, activated thrombin and trypsin, may stimulate ET-1 production in a paracrine fashion; produced ET-1 may exaggerate the splanchnic microcirculation; and progressive ischemia may lead to necrosis of the pancreas and intestine.

Role of the gut in the course of severe acute pancreatitis

INTRODUCTION

The pathogenesis of acute pancreatitis remains elusive. Sepsis and multiple organ failure continue to cause death (overall mortality rate, approximately 10%) despite immense improvements in supportive, radiologic, and surgical therapy. The gut appears to play a key role in the development of these complications.

AIM

To critically review the evidence implicating the gut in the pathogenesis of acute pancreatitis.

METHODS

Relevant English-language literature or abstracts cited in the MEDLINE database were reviewed.

RESULTS AND CONCLUSION

Gram-negative enteric organisms account for most infections of pancreatic necrosis and subsequent sepsis, which suggests the gut as a source. Intestinal permeability is increased early in patients with severe acute pancreatitis and correlates with endotoxemia, which suggests translocation as a possible mechanism. The pathogenesis of the deranged function of the gut mucosal barrier and the possible sites of increase in intestinal permeability are discussed. The gut also plays a role in priming neutrophils and the release of inflammatory cytokines, which initiate and propagate nearly all the detrimental consequences of severe inflammation and sepsis. Future research avenues and potential therapeutic measures that may restore and preserve gut barrier function are explored.

The effect of endothelin-1 receptor antagonists in acute experimental pancreatitis in the rats

The relative role of endothelin-1 receptors, ET(A) and ET(B) blockade in acute pancreatitis (AP) remains controversial. The aim of the study was to compare the effect of nonselective ET(A/B) antagonist (LU 302872) and selective ET(A)antagonist (LU 302146) in severe taurocholate AP in rats. Male Wistar rats with AP were treated with increasing doses: 1, 5 or 10 mg/kg b.w. of antagonists i.p. at 0, 6, 12, 18 h after induction of AP. In 24 h survivors, free active trypsin (FAT) and total potential trypsin (TPT), chymotrypsin and lipase in 12,000 x g supernatants of the pancreases were assayed. The index of trypsinogen activation (% FAT/TPT) was elevated in untreated AP to 29.2 +/- 5.0 vs 5.4 +/- 0.9 in the control (p < 0.001). ET(A/B) antagonist at increasing doses, diminished this index to 9.8 +/- 2.7, 10.3 +/- 1.6 and 10.1 +/- 2.0 respectively (p < 0.005). ET(A) antagonist reduced % FAT/TPT ratio to 10.6 +/- 1.9 (p < 0.005), 13.4 +/- 0.5 (p < 0.001) and 10.2 +/- 2.4 (p < 0.005) at respective doses. Both antagonists to a similar degree reduced the histological scores of inflammation, hemorrhages and necrosis. The increase in chymotrypsin and lipase activities after 24 h was not significant. In conclusion, both nonselective ET(A/B) and selective ET(A) antagonists attenuated to similar degree the augmented trypsinogen activation and pancreatic injury in taurocholate acute experimental pancreatitis in rats. Endothelin-1 receptor antagonists could be beneficial in the course of acute pancreatitis by the attenuation of trypsinogen activation.

Endothelin A but not endothelin B receptor blockade reduces capillary permeability in severe experimental pancreatitis

INTRODUCTION

Microcirculatory disorders, in particular increased capillary permeability (CapPerm), contribute to the multiple organ dysfunction syndrome in severe acute pancreatitis (AP). Endothelin receptor antagonists (ET-RA) have been shown to stabilize capillary leakage and improve organ function in AP.

AIM

To find out which endothelin receptor subtype (ET-A or ET-B) mediates the changes in CapPerm.

METHODOLOGY

Severe AP was induced in rats by intraductal bile salt infusion and i.v. cerulein. Animals were randomized to receive (1) saline; (2) selective ET-A-RA (LU-135252; 30 mg/kg); (3) selective ET-B-RA (A-192621); (4) nonselective ET-RA (LU-135252; 120 mg/kg); or (5) combined ET-A/B-RA (30 mg/kg LU-135252 + A-192621). Capillary blood flow (CBF) and CapPerm in the pancreas and colon and leukocyte rolling in mesenteric venules were determined.

RESULTS

Selective ET-A-RA increased CBF and decreased CapPerm in the pancreas and colon by 90-147% and reduced leukocyte rolling in AP but had no effect in healthy controls. Selective ET-B-RA increased pancreatic CBF (2.3 +/- 0.03 versus 2.1 +/- 0.04 nL/min) and enhanced CapPerm in the pancreas and colon by 24-35% in healthy controls but had no effect in AP. Blockade of both receptors produced effects similar to but less pronounced than those of selective ET-A-RA.

CONCLUSIONS

Blockade of ET-A and ET-B receptors has different effects on CapPerm in healthy animals and those with AP. This may explain the inconclusive results reported with nonselective ET-RA. In severe AP, blockade of ET-A but not ET-B receptors reduces CapPerm.