Endotoxin translocation in two models of experimental acute pancreatitis

Bacterial translocation in acute pancreatitis

Bacterial translocation is a phenomenon in which live bacteria or their products cross the intestinal barrier to other organs or the circulatory system. Gut translocation of bacteria has been reported in both animal models, and clinical trials often accompany acute pancreatitis and are believed to be linked to patient outcome, especially in severe acute pancreatitis. Therefore, the mechanisms of intestinal bacterial translocation in acute pancreatitis have become a topic of interest in recent years. This review discusses Bacterial translocation in acute pancreatitis, identifies possible mechanisms of action, and provides an overview of the methods used to detect Bacterial translocation in acute pancreatitis. This review also highlights areas that require further research.

Enteral versus parenteral nutrition in critically ill patients with severe pancreatitis: a meta-analysis

Whether enteral nutrition (EN) is superior to parenteral nutrition (PN) in critically ill patients with severe acute pancreatitis remains unknown. The objective of this meta-analysis was to assess the effects of EN versus PN on clinical outcomes in a subgroup of pancreatitis patients. Relevant randomized controlled trials (RCTs) were searched in Scopus, PubMed and Web of Science from inception to August 2016. Ultimately, five RCTs including 348 patients were enrolled in this analysis. Compared with PN, EN was associated with a significant reduction in overall mortality (risk ratio (RR)=0.36, 95% confidence interval (CI) 0.20-0.65, P=0.001) and the rate of multiple organ failure (RR=0.39, 95% CI 0.21-0.73, P=0.003). EN should be recommended as the preferred route of nutrition for critically ill patients with severe acute pancreatitis.

Intestinal barrier dysfunction and increased COX-2 gene expression in the gut of elderly rats with acute pancreatitis

BACKGROUND/OBJECTIVES

The clinical course of acute pancreatitis can vary from mild to severe. In its most severe manifestation, acute pancreatitis is associated with an exacerbated systemic inflammatory response and high mortality rates. The severe form of acute pancreatitis is more frequent in elderly patients than in young patients, but the mechanisms underlying this difference are still under investigation.

METHODS

Rats were divided into two groups as follows: Group 1, young rats; and Group 2, old rats. Acute pancreatitis group was induced by a retrograde injection of a sodium taurocholate solution into the biliopancreatic duct. Using this model of acute pancreatic injury, we designed a study to investigate possible differences in microbial translocation and characteristics of the intestinal barrier between elderly and young rats.

RESULTS

There was a significantly higher number of bacterial colonies in the pancreas of elderly rats compared with young rats following pancreas injury, which was associated with a more severe local intestinal inflammatory response that included elevated gene expression of COX-2 and a decreased gene expression of tight junction proteins.

CONCLUSIONS

We conclude that intestinal damage during acute pancreatitis is exacerbated in elderly rats compared with young rats and that COX-2 inhibition could be a potential therapeutic target to offer tailored treatment for acute pancreatitis in the elderly.

Pancreatic hyperenzymemia is associated with bacterial culture positivity, more severe and right-sided colitis

BACKGROUND/AIM

Several studies reported pancreatic hyperenzymemia (PHE) related to acute colitis. However, there is no consensus on its clinical significance. This study was addressed to find the clinical significance of PHE in acute colitis.

METHODS

Pancreatic hyperenzymemia was defined as abnormal increase in serum concentrations of the pancreatic enzymes by three times of normal upper range without definite pancreatic symptoms and evidence of pancreatitis at abdominal CT imaging of pancreatic disease. And clinical and laboratory and biologic parameters of PHE group and normal pancreatic enzymemia (NPE) group were compared.

RESULTS

A total of 1,069 patients admitted to hospitals due to acute colitis were analyzed. Of these patients, 2.99 % (32/1,069) showed PHE. PHE group showed more severe symptoms and had longer hospital stays than the NPE group (12.15 vs. 4.59 days; P < 0.001). Multivariable analysis showed that right-sided colitis (OR 2.846; 95 % CI 1.122-7.224; P = 0.028) and culture positivity (OR 3.346; 95 % CI 1.119-10.008; P = 0.031) are associated with PHE during acute colitis. Also, PHE group was more common when a microorganism could be identified in the cultures (28.1 vs. 7.0 %; P = 0.003), especially blood culture. Among patients with positive cultures, Salmonella spp. had a positive correlation with the right-sided colitis and PHE (amylase P = 0.002; lipase P = 0.029), Salmonella serovar typhimurium (group B) was especially related to increased serum lipase but not to increased serum amylase (lipase; P = 0.041: amylase; P = 0.485).

CONCLUSION

Pancreatic hyperenzymemia is associated with right-sided colitis, bacterial culture positivity, and severe acute colitis.

The loss of αSNAP downregulates the expression of occludin in the intestinal epithelial cell of acute pancreatitis model

BACKGROUND AND OBJECTIVE

Intestinal barrier damage is an important event during the occurrence and progression of severe acute pancreatitis. The expression of occludin, one of the main components of the intestinal barrier proteins, is regulated by various factors related to intestinal barrier formation and the remodeling process. The αSNAP, as a novel membrane protein, is ubiquitously expressed in intestinal epithelial cells. This study aimed to investigate the role of αSNAP in acute pancreatitis and the relationship between occludin and αSNAP.

METHODS

Mild and severe acute pancreatitis models were established by retrograde injections of 0.5% and 3.8% sodium taurocholate solutions, respectively, into rat pancreaticobiliary ducts. The animals were killed at 1, 2, and 3 days after the injection, and the pathological changes of the pancreas and intestinal mucosa, the changes in intestinal permeability, and the protein expression of occludin and αSNAP were assessed. Cultured epithelial IEC-6 cells were further infected with lentiviral αSNAP shRNA, cell apoptosis was determined with flow cytometry (FCM), and any changes in occludin expression were detected by Western blotting and immunofluorescent staining.

RESULTS

This pathologic study of a rat acute pancreatitis model indicated pancreatic tissue necrosis and inflammatory cell infiltration; the intestinal villi in the severe acute pancreatitis (SAP) group demonstrated edema, lodging, atrophy, and intestinal epithelial cell necrosis, and shedding. The intestinal permeability in rats with pancreatitis increased significantly. The SAP group showed significantly increased levels of serum TNF-α and endotoxins. The results of immunofluorescent staining and Western blotting revealed that compared with the SO (sham operation) and MAP (mild acute pancreatitis) groups, the SAP group displayed significantly downregulated protein expressions of αSNAP and occludin in the intestinal epithelial cells. After the lentiviral transduction of αSNAP shRNA, apoptosis in IEC-6 cells was drastically increased, whereas the expression of occludin was decreased significantly.

CONCLUSION

The downregulated expression of αSNAP in intestinal epithelial cells leads to reduced occludin expression and enhanced apoptosis of intestinal epithelial cells. Hence, the permeability of the intestinal barrier may be increased in a severe acute pancreatitis model.

Fractal-like kinetics of intracellular enzymatic reactions: a chemical framework of endotoxin tolerance and a possible non-specific contribution of macromolecular crowding to cross-tolerance

BACKGROUND

The response to endotoxin (LPS), and subsequent signal transduction lead to the production of cytokines such as tumor necrosis factor-α (TNF-α) by innate immune cells. Cells or organisms pretreated with endotoxin enter into a transient state of hyporesponsiveness, referred to as endotoxin tolerance (ET) which represents a particular case of negative preconditioning. Despite recent progress in understanding the molecular basis of ET, there is no consensus yet on the primary mechanism responsible for ET and for the more complex cases of cross tolerance. In this study, we examined the consequences of the macromolecular crowding (MMC) and of fractal-like kinetics (FLK) of intracellular enzymatic reactions on the LPS signaling machinery. We hypothesized that this particular type of enzyme kinetics may explain the development of ET phenomenon.

METHOD

Our aim in the present study was to characterize the chemical kinetics framework in ET and determine whether fractal-like kinetics explains, at least in part, ET. We developed an ordinary differential equations (ODE) mathematical model that took into account the links between the MMC and the LPS signaling machinery leading to ET. We proposed that the intracellular fractal environment (MMC) contributes to ET and developed two mathematical models of enzyme kinetics: one based on Kopelman's fractal-like kinetics framework and the other based on Savageau's power law model.

RESULTS

Kopelman's model provides a good image of the potential influence of a fractal intracellular environment (MMC) on ET. The Savageau power law model also partially explains ET. The computer simulations supported the hypothesis that MMC and FLK may play a role in ET.

CONCLUSION

The model highlights the links between the organization of the intracellular environment, MMC and the LPS signaling machinery leading to ET. Our FLK-based model does not minimize the role of the numerous negative regulatory factors. It simply draws attention to the fact that macromolecular crowding can contribute significantly to the induction of ET by imposing geometric constrains and a particular chemical kinetic for the intracellular reactions.

Effect of enteral nutrition and ecoimmunonutrition on bacterial translocation and cytokine production in patients with severe acute pancreatitis

BACKGROUND

Severe acute pancreatitis (SAP) with severe complications such as multiple organ failure, necrosis, abscess, and formation of pancreatic pseudocysts often gives rise to a high mortality despite intensive treatment. Parenteral nutrition (PN), elemental enteral nutrition, and ecoimmunonutrition (EIN) hastened the recovery of SAP patients, stimulated gastrointestinal motility, and alleviated the degree of systemic inflammatory response syndrome. This study aimed to examine the effects of enteral nutrition (EN) and EIN on bacterial translocation and cytokine production in patients with SAP.

METHODS

One hundred eighty-three SAP patients were randomly divided into three groups receiving PN, EN, or EN + EIN. Acute Physiology and Chronic Health Evaluation II scores, complications (systemic inflammatory response syndrome, multiorgan failure, and infections), intestinal bacterial strains of stool, and plasma concentrations of endotoxin, tumor necrosis factor α (TNF-α), and interleukin (IL) 6 and IL-10 were evaluated.

RESULTS

The percentage of pancreatic sepsis, multiple organ dysfunction syndrome, and mortality was significantly lower in the EN group and was further lower in the EN + EIN group than that in the PN group. The plasma concentrations of TNF-α and IL-6 and APACHE II scores were significantly decreased in the EN group and were further lowered in the EN + EIN group than those in the PN group. The plasma concentration of IL-10 was higher in the EN group and was further increased in the EN + EIN group than that in the PN group.

CONCLUSIONS

EN plays effective roles in the treatment of SAP by decreasing the expression of endotoxin, TNF-α, and IL-6 and the bacterial translocation, enhancing the expression of IL-10, and the combination of EIN with EN results in more therapeutic benefits than EN alone.

Microbial translocation across the GI tract

The lumen of the gastrointestinal (GI) tract is home to an enormous quantity of different bacterial species, our microbiota, that thrive in an often symbiotic relationship with the host. Given that the healthy host must regulate contact between the microbiota and its immune system to avoid overwhelming systemic immune activation, humans have evolved several mechanisms to attenuate systemic microbial translocation (MT) and its consequences. However, several diseases are associated with the failure of one or more of these mechanisms, with consequent immune activation and deleterious effects on health. Here, we discuss the mechanisms underlying MT, diseases associated with MT, and therapeutic interventions that aim to decrease it.

Protective effects of Ligustrazine, Kakonein and Panax Notoginsenoside on the small intestine and immune organs of rats with severe acute pancreatitis

BACKGROUND

Severe acute pancreatitis (SAP) is characterized by fatal pathogenic conditions and a high mortality. It is important to study SAP complicated with multiple organ injury. In this study we compared the protective effects of three traditional Chinese medicines (Ligustrazine, Kakonein and Panax Notoginsenoside) on the small intestine and immune organs (thymus, spleen and lymph nodes) of rats with SAP and explored their mechanism of action.

METHODS

One hundred forty-four rats with SAP were randomly divided into model control, Ligustrazine-treated, Kakonein-treated, and Panax Notoginsenoside-treated groups (n=36 per group). Another 36 normal rats comprised the sham-operated group. According to the different time points after operation, the experimental rats in each group were subdivided into 3-, 6- and 12-hour subgroups (n=12). At various time points after operation, the mortality rate of rats and pathological changes in the small intestine and immune organs were recorded and the serum amylase levels were measured.

RESULTS

Compared to the model control groups, the mortality rates in all treated groups declined and the pathological changes in the small intestine and immune tissues were relieved to different degrees. The serum amylase levels in the three treated groups were significantly lower than those in the model control group at 12 hours. The pathological severity scores for the small intestinal mucosa, thymus and spleen (at 3 and 12 hours) in the Ligustrazine-treated group, for the thymus (at 3 and 12 hours) and spleen (at 3 and 6 hours) in the Kakonein-treated group, and for the thymus (at 3 hours) and spleen (at 3 hours) in the Panax Notoginsenoside-treated group were significantly lower than those in the model control group. The pathological severity scores of the small intestinal mucosa (at 6 and 12 hours) and thymus (at 6 hours) in the Ligustrazine-treated group were significantly lower than those in the Kakonein- and Panax Notoginsenoside-treated groups.

CONCLUSIONS

All the three traditional Chinese drugs significantly alleviated the pathological changes in the small intestine and immune organs of SAP rats. Ligustrazine was the most effective one among them.

Effect of major abdominal surgery on endotoxin release and expression of Toll-like receptors 2/4

BACKGROUND

Surgery can cause endotoxemia, and endotoxin aggregates to Toll-like receptors and acts proinflammatory; repetitive endotoxin application can cause tolerance. The objective of the study is to characterize early inflammatory response and expression of TLR2/4 during major abdominal surgery.

MATERIALS AND METHODS

A prospective controlled study of 20 patients with elective major abdominal surgery was performed. Blood samples were collected before and at a defined time after surgery. Endotoxemia, capability of plasma to inactivate endotoxin, cytokine release of LPS-stimulated mononuclear cells, quantitative TLR mRNA expression, and plasma concentrations of TNFalpha, IL-6, C-reactive protein (CRP), alpha(1)-acid glycoprotein, transferrin, and albumin were measured.

RESULTS

Surgery caused endotoxemia (p = 0.053), and the capability of plasma to inactivate endotoxin was reduced (p = 0.0002). Two hours postoperatively, the plasma concentrations of TNFalpha and IL-6 peaked significantly, but the liberation capacity of mononuclear cells for cytokines (TNFalpha, IL-1beta, IL-6) was significantly reduced. The concentration of CRP and alpha(1)-acid glycoprotein peaked 48 h postoperatively, but those of transferrin and albumin were significantly decreased (p < 0.001, respectively). Median mRNA expression of TLR2 and TLR4 of mononuclear cells was not altered, and there was no obvious trend over time.

CONCLUSION

Major abdominal surgery is associated with endotoxemia, reduced capability of plasma to inactivate endotoxin, cytokine kinetics resembling those of healthy man after experimentally given LPS, and substantial acute-phase reaction. The cytokine liberation of mononuclear cells suggests a state of postoperative endotoxin tolerance. Despite these substantial changes, trends in TLR2/4 expression are not obvious.

Protecting effects of dexamethasone on thymus of rats with severe acute pancreatitis

Purpose. To study the protecting effects of dexamethasone on thymus of rats with severe acute pancreatitis (SAP). Methods. The SAP rats were randomly assigned to the model group and dexamethasone-treated group, the other normal healthy rats were assigned to the sham operation group. The rat survival, thymus pathological changes, apoptotic index, as well as expression levels of NF-κB, P-selectin, Bax, Bcl-2, and Caspase-3 protein of all groups were observed, respectively, at 3 hours, 6 hours, and 12 hours. The contents of amylase and endotoxin in plasma as well as the contents of TNF-α, PLA2, and NO in serum were determined. Results. There was no marked difference between the model group and treated group in survival. The contents of different indexes in blood of treated group were lower than those of the model group to various degrees at different time points. The thymus pathological score was lower in treated group than in model group at 12 hours.The treated group in Caspase-3 protein expression of thymus significantly exceeded the model group at 12 hours. The apoptotic index was significantly higher in treated group than in model group. Conclusion. Dexamethasone has protecting effects on thymus of SAP rats.

Experimental study of therapeutic efficacy of Baicalin in rats with severe acute pancreatitis

AIM: To observe the therapeutic efficacy of Baicalin in rats with severe acute pancreatitis (SAP) and explore its therapeutic mechanisms.

METHODS: The SAP rat models were randomly divided into the model control group, Baicalin treatment group, octreotide treatment group and sham operation group. All groups were randomly subdivided into 3 h, 6 h and 12 h groups with 15 rats in each group. The survival, ascites volume and pathological changes of pancreas in all rats were observed at different time points after operation. The plasma amylase content and serum TNF-α, IL-6, malonaldehyde (MDA) and PLA₂ contents were also determined.

RESULTS: The survival was not obviously different between the treated groups, and was significantly higher in treated groups at 12 h compared to the model control group (P < 0.05, 15 vs 10). The ascites/body weight ratio at 3 h and 6 h was significantly lower in Baicalin treatment group compared to the model control group and octreotide treatment group (P < 0.05, 1.00 vs 2.02 and 1.43 and P < 0.001, 2.29 (1.21) vs 2.70 (0.80) and 2.08 (2.21), respectively). The contents of amylase, TNF-α, IL-6, MDA and PLA₂ were significantly lower in the treated groups than in the model control group (P < 0.05, 4342 vs 5303, 5058 vs 6272 in amylase, P < 0.01, 21.90 vs 36.30, 23.80 vs 39.70, 36 vs 54.35 in MDA and 56.25 vs 76.10 in PlA₂, or P < 0.001, 65.10 and 47.60 vs 92.15 in TNF-α, 3.03 vs 5.44, 2.88 vs 6.82, 2.83 vs 5.36 in IL-6, respectively). The pathological scores of pancreas in the treated groups were significantly lower than that in the model control group (P < 0.05, 9.00 vs 10.05, 6.00 vs 9.00, 8.00 vs 10.05), but no marked difference was found between the treated groups.

CONCLUSION: The Baicalin injection has significant therapeutic effects on SAP rats, its effects are similar to those of octreotide. The Baicalin injection is also cheap and has a big application range, quite hopefully to be used in clinical treatment of SAP.

Changes of endotoximia, cytokines and nitric oxide and therapeutic effects of sandostatin in rats with severe acute pancreatitis

AIM: To study the roles of endotoximia, cytokines and nitric oxide in the development of severe acute pancreatitis (SAP) and the therapeutic effects of sandostatin (SS) in rats.

METHODS: SAP models were induced by retrograde injection of 15 g/L sodium deoxycholate and then treated by SS. The plasma levels of endotoxin (ET), lipid peroxide (LPO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and nitric oxide (NO), as well as the expression LPO, TNF-α, IL-6 and NO in pancreatic tissues, were measured. The changes of pancreatic histology were examined under light microscope.

RESULTS: As Compared with those in sham operation group, the plasma levels of ET, LPO, TNF-α, IL-6 and NO were markedly higher in SAP group (P < 0.01), and the changes of ET, LPO, TNF-α and NO at 6 h were higher (898 ± 114 EU/L, 24.58 ± 1.23 μmol/L, 246.3 ± 16.5 ng/L, 162.8 ± 10.9 mmol/L, P < 0.05) than those at 12 and 24 h. The changes of LPO, TNF-α, IL-6 and NO in pancreatic tissues of SAP group were obviously higher in comparison with those of sham group (3.31 ± 0.85 μmol/g vs0.33 ± 0.04 μmol/g, P < 0.01; 2.57 ± 0.14 ng/g vs 0.16 ± 0.04 ng/g, P < 0.01; 85.6 ± 24.6 ng/g vs 32.5 ± 5.7 ng/g, P < 0.01; 15.3 ± 1.2 mmol/g vs 6.6 ± 1.4 mmol/g, P < 0.01); and severe damages of pancreatic tissues were observed under light microscope. In SAP group, the plasma levels of LPO, TNF-α, IL-6 and NO were significantly correlated with ET level (r = 0.858,P < 0.01; r = 0.958, P < 0.01; r = 0.918, P < 0.01; r = 0.875, P < 0.01). The indexes mentioned above in SS group were obviously ameliorated in comparison with those in SAP group (P < 0.01).

CONCLUSION: Endotoximia, cytokines and NO play important roles in the development of severe acute pancreatitis. Sandostatin can block the chain reaction caused by these factors.

The isolated perfused liver response to a 'second hit' of portal endotoxin during severe acute pancreatitis

BACKGROUND/AIM

During severe acute pancreatitis (AP), the liver may show an exaggerated response to the inflammatory products of gut injury transported in the portal vein. Our aim was to explore liver proinflammatory mediator production after a 'second hit' of portal lipopolysaccharide (LPS) during AP.

METHODS

Twenty-four rats underwent one of three 'first-hit' scenarios: (1) severe AP induced by intraductal glycodeoxycholic acid injection and intravenous caerulein infusion, (2) sham laparotomy, or (3) no first intervention. Eighteen hours later, all animals received a 'second hit' of portal LPS in an isolated liver perfusion system. Tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6 concentrations were measured in portal and systemic serum, and in the perfusate 30 and 90 min after the 'second hit'. Neutrophil activation by the perfusate was assayed using dihydrorhodamine-123 fluorescence.

RESULTS

We observed a six-fold increase in IL-6 concentration across the liver during AP. All livers produced TNF-alpha after the portal LPS challenge, but this was not exaggerated by AP. No differential neutrophil activation by the perfusate was seen.

CONCLUSION

TNF-alpha, IL-1beta, IL-6 and neutrophil activator production by the isolated perfused liver, in response to a 'second hit' of portal LPS, does not appear to be enhanced during AP.