Compartmentalization of the protease-antiprotease balance in early severe acute pancreatitis

Sampling Thoracic Duct Lymph After Esophagectomy: A Pilot Study Investigating the "Gut-Lymph" Concept

Introduction: Gut-lymph in animal models of acute disease is altered by intestinal ischemia and contributes to the development of systemic inflammation and organ dysfunction. Investigating gut-lymph in humans is hampered difficulty in accessing the thoracic duct (TD) for lymph sampling. The aims of this study were to develop and pilot a technique of intraoperative TD cannulation with delayed embolization to serially measure TD lymph pressure, flow, and composition (including markers of intestinal injury) during the early postoperative period and in response to enteral feeding and vasopressor treatment. Methods: A Seldinger technique was used for percutaneous TD cannulation during an Ivor Lewis esophagogastrectomy. Lymph flow rate and pressure were measured. TD lymph and plasma were sampled at 12 hourly intervals for up to 120 hours after surgery and before TD embolization. Biochemistry, lipids, cytokines, and markers of intestinal injury were measured before and after enteral feeding commenced at 36 hours. Results: Intraoperative TD cannulation was technically feasible in three of four patients. Delayed TD embolization was only successful in one of three patients, with two patients requiring a re-thoracotomy to treat chylothorax. Profound changes in TD composition, but not flow rate, occurred over time and in response to enteral feeding and vasopressors. TD lymph compared with plasma had significantly higher lipase (1.4-17 × ), interleukin-6 (8-108 × ), tumor necrosis factor-α (2.7-17 × ), d-lactate (0.3-23 × ), endotoxin (0.1-41 × ), and intestinal fatty acid binding protein (1.1-853 × ). Conclusions: Although TD cannulation and lymph sampling were successful, TD embolization failed in two of three patients. The composition of sampled TD lymph changed dramatically in response to enteral feeding, indicating intestinal ischemia that could be exacerbated by nonselective vasopressors. The higher concentration of proinflammatory cytokines and gut injury markers in TD lymph, compared with plasma, lends support to the gut-lymph concept.

Indications, techniques, and clinical outcomes of thoracic duct interventions in patients: a forgotten literature?

BACKGROUND

The evolution of the "gut-lymph concept" has promoted thoracic duct (TD) lymph drainage as a possible treatment to reduce systemic inflammation and end-organ dysfunction in acute illness. The aim was to review the published experience of thoracic duct interventions (TDIs) aimed at improving clinical outcomes.

METHODS

A search of three databases (MEDLINE, EMBASE, and EMBASE CLASSIC) over the last 60 y. The indications for intervention, the technique, and clinical outcomes were reviewed.

RESULTS

There were a wide range of indications for TDI. These included reducing rejection after transplantation, treating inflammatory diseases, and reducing chronic failure of the liver, kidney, and heart. The techniques included TD cannulation and lymphovenuous fistula. The outcomes were variable and often equivocal, and this appears to reflect poor design quality. There is clinical equipoise regarding a therapeutic role of (TD lymph drainage in acute pancreatitis, and probably other acute diseases.

CONCLUSIONS

Until well-designed clinical trials are undertaken, the clinical benefits of TDIs will remain promising, but uncertain.

Time-course proteomic analysis of taurocholate-induced necrotizing acute pancreatitis

Acute pancreatitis is an inflammatory disease of the pancreas, which varies greatly in course and severity. Severe forms are associated with serious local and/or systemic complications, and eventually death. The pathobiology of acute pancreatitis is complex. Animal models have been developed to investigate pathobiological processes and identify factors determining disease course. We performed a time-course proteomic analysis using a rat model of severe necrotizing acute pancreatitis induced by taurocholate perfusion in the pancreatic ducts. Results showed that levels of proteins associated to a given biological process changed in a coordinated fashion after disease onset. It was possible to follow the response of a particular pathobiological process to pancreatitis induction and to compare the course of protein pathways. Proteins involved in acinar cell secretion were found to follow a different kinetics than other cellular processes. After an initial decrease, secretory pathway-associated proteins raised again at 18 h post-induction. This phenomenon coincided with a burst in the expression of pancreatitis-associated protein (REG3A), an acute phase protein produced by the exocrine pancreas, and with the decrease of classical markers of pancreatic injury, suggesting that the expression of proteins associated to the secretory pathway may be a modulating factor of pancreas injury.

BIOLOGICAL SIGNIFICANCE

Acute pancreatitis (AP) is a complex inflammatory disease, the pathobiology of which is not yet fully understood. Various animal models, relying on different mechanisms of disease induction, have been developed in order to investigate pathobiological processes of AP. In this study, we performed a time-course proteomic analysis to investigate changes of the pancreas proteome occurring in an experimental model of AP induced by perfusion of taurocholate, a bile acid, into the pancreatic duct. This experimental model is characterized by a severe disease with pancreatic necrosis and systemic inflammation. The objectives of this study were to determine the kinetics of functionally related proteins in the early steps of the experimental disease in order to identify protein pathways playing key roles in AP pathobiology and to correlate these data with parameters classically used to assess disease severity. The present work provides for the first time an overview of protein expression in the pancreas during the course of taurocholate-induced necrotizing AP. We believe that correlation of these results with data obtained using proteomic or biochemical approaches in various experimental models of AP will help in highlighting new features, generating hypotheses and constitute therefore a strong and reliable basis for further targeted investigations.

Effect of octreotide on enteric motor neurons in experimental acute necrotizing pancreatitis

Background/Aims

Amelioration of intestinal dysmotility and stasis during the early period of acute necrotizing pancreatitis (ANP) appears to be important to reduce the risks of secondary pancreatic infection. We aimed to characterize the association between the neuropathy of the enteric nervous system and gut dysfunction and to examine the effect of octreotide on motor innervation in the early stage of ANP.

Methodology/Principal Findings

The rats were randomly divided into eight groups: control+saline; control+octreotide; ANP+saline and ANP+octreotide (24 h, 48 h, 72 h). The spontaneous activity of ileal segments and the response to ACh, l-NNA were recorded. The alterations of myenteric neuronal nitric oxide synthase (nNOS), choline acetyltransferase (CHAT), PGP9.5 and somatostatin receptor 2 (SSTR₂) immunoreactive cells were evaluated by immunofluorescence and the protein expression of nNOS and CHAT were evaluated by western blot. We found the amplitude of spontaneous contractions at 48 h and the response to ACh at 24 h declined in the ANP+saline rats. A higher contractile response to both ACh and to l-NNA was observed in the ANP+octreotide group, compared with the ANP+saline rats at 24 h. A significant reduction in the nNOS and cholinergic neurons was observed in ANP+saline rats at the three time points. However, this reduction was greatly ameliorated in the presence of octreotide at 24 h and 48 h. The protein expression of CHAT neurons at 24 h and the nNOS neurons at 48 h in the ANP+octreotide rats was much higher than the ANP+saline rats.

Conclusion

The pathogenesis of ileus in the early stage of ANP may be related to the neuropathy of the enteric nervous system. Octreotide may reduce the severity of ileus by lessening the damage to enteric motor innervation.

The use of animal models to study bacterial translocation during acute pancreatitis

Infection of pancreatic necrosis with intestinal flora is accepted to be a main predictor of outcome during severe acute pancreatitis. Bacterial translocation is the process whereby luminal bacteria migrate to extraintestinal sites. Animal models were proven indispensable in detecting three major aspects of bacterial translocation: small bowel bacterial overgrowth, mucosal barrier failure, and disturbed immune responses. Despite the progress made in the knowledge of bacterial translocation, the exact mechanism, origin and route of bacteria, and the optimal prophylactic and treatment strategies remain unclear. Methodological restrictions of animal models are likely to be the cause of this uncertainty. A literature review of animal models used to study bacterial translocation during acute pancreatitis demonstrates that many experimental techniques per se interfere with intestinal flora, mucosal barrier function, or immune response. Interference with these major aspects of bacterial translocation complicates interpretation of study results. This paper addresses these and other issues of animal models most frequently used to study bacterial translocation during acute pancreatitis.

Differential kinetics of plasma CD105 and transforming growth factor beta expression early in human acute pancreatitis

OBJECTIVES

The interaction of transforming growth factor beta (TGF-beta) with CD105 (endoglin) is an essential step in the maintenance of endothelial cell quiescence. The importance of this interaction during the critical early phases of acute pancreatitis is unknown. This study explores patterns of expression of CD105 and TGF-beta in plasma during human acute pancreatitis.

METHODS

Forty-one patients with a clinical diagnosis of acute pancreatitis constitute the study population. Venous blood samples were taken at admission and on the fifth day. Enzyme-linked immunosorbent assay was performed for CD105, TGF-beta1, TGF-beta3, CD105/TGF-beta1, and CD105/TGF-beta3 complexes.

RESULTS

TGF-beta1 levels were significantly elevated on admission in the acute pancreatitis group compared with controls and were further elevated in delayed samples. In contrast, admission CD105 levels were similar to those in controls, but in delayed samples, there was a significant reduction in CD105. Levels of TGF-beta3, CD105/TGF-beta1, and CD105/TGF-beta3 did not differ between groups.

CONCLUSIONS

This is the first report to investigate the interplay between plasma expression of CD105, TGF-beta1, TGF-beta3, and ligand complexes in acute pancreatitis. The results of this study confirm previous findings that increased expression of TGF-beta1 is a feature of severe acute pancreatitis. The absence of a parallel elevation in CD105 or CD105/TGF-beta ligand complexes is previously unreported and may suggest that angiogenesis mediated by the interaction between CD105 and TGF-beta is not an early feature of this disease.