Patterns of bacterial translocation in experimental biliary obstruction

Risk factors for post-endoscopic retrograde cholangiopancreatography cholangitis in patients with hepatic alveolar echinococcosis-an observational study

BACKGROUND

Hepatic alveolar echinococcosis (HAE) is considered to be one of the most deadly chronic parasitic diseases in the world. We have shown that the incidence of cholangitis in patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) was increased significantly. On this finding, we carried out, a preliminary study on the risk factors for cholangitis after ERCP.

AIMS

To retrospectively detect the risk factors for post-ERCP cholangitis in patients with biliary tract affected by HAE.

METHODS

The study included data from 51 cases of AE who had undergone therapeutic ERCP between January 2015 and December 2019. Demographic and treatment data were extracted from the medical records, and the association between potential risk factors and the development of post-ERCP cholangitis was evaluated using a collected database.

RESULTS

There were five cases of mild cholangitis after ERCP (Tokyo criteria), and no moderate or severe cholangitis occurred. The incidence rate of cholangitis after ERCP was 9.8%. Univariate analysis showed hilar bile duct stenosis (p = .016), endoscopic retrograde biliary drainage (p = .007), a stent diameter ≥8.5 Fr (p = .000) and single stent implantation (p = .010) were risk factors for post -ERCP cholangitis. All cases of cholangitis improved under conservative treatment.

CONCLUSION

Patients with hilar bile duct compression or endoscopic retrograde biliary drainage appeared to be more likely to develop post-ERCP cholangitis. The number and diameter of biliary stents may influence post-ERCP cholangitis. Sample size and clinical heterogeneity are two insurmountable difficulties, and a larger sample size needs to be collected to verify the risk factors for screening. KEY MESSAGESMany studies reported the post-ERCP complications in patients with hepatic alveolar echinococcosis and found that the incidence of post-ERCP cholangitis was significantly high. Therefore, we conducted a preliminary study on the risk factors of postoperative cholangitis in patients who underwent ERCP.The incidence rate of cholangitis after ERCP was 9.8%. We found that hilar bile duct stenosis, and endoscopic retrograde biliary drainage, were risk factors for cholangitis, and stent diameter and the number of stent implantation may influence the incidence rate of cholangitis after ERCP.Sample size and clinical heterogeneity are two insurmountable difficulties, and a larger sample size needs to be collected to verify the risk factors of screening.

Oral-Gut Microbiome Axis in Gastrointestinal Disease and Cancer

It is well-known that microbiota dysbiosis is closely associated with numerous diseases in the human body. The oral cavity and gut are the two largest microbial habitats, playing a major role in microbiome-associated diseases. Even though the oral cavity and gut are continuous regions connected through the gastrointestinal tract, the oral and gut microbiome profiles are well-segregated due to the oral-gut barrier. However, the oral microbiota can translocate to the intestinal mucosa in conditions of the oral-gut barrier dysfunction. Inversely, the gut-to-oral microbial transmission occurs as well in inter- and intrapersonal manners. Recently, it has been reported that oral and gut microbiomes interdependently regulate physiological functions and pathological processes. Oral-to-gut and gut-to-oral microbial transmissions can shape and/or reshape the microbial ecosystem in both habitats, eventually modulating pathogenesis of disease. However, the oral-gut microbial interaction in pathogenesis has been underappreciated to date. Here, we will highlight the oral-gut microbiome crosstalk and its implications in the pathogenesis of the gastrointestinal disease and cancer. Better understanding the role of the oral-gut microbiome axis in pathogenesis will be advantageous for precise diagnosis/prognosis and effective treatment.

Oral–Gut Microbiome Axis in Gastrointestinal Disease and Cancer

It is well-known that microbiota dysbiosis is closely associated with numerous diseases in the human body. The oral cavity and gut are the two largest microbial habitats, playing a major role in microbiome-associated diseases. Even though the oral cavity and gut are continuous regions connected through the gastrointestinal tract, the oral and gut microbiome profiles are well-segregated due to the oral–gut barrier. However, the oral microbiota can translocate to the intestinal mucosa in conditions of the oral–gut barrier dysfunction. Inversely, the gut-to-oral microbial transmission occurs as well in inter- and intrapersonal manners. Recently, it has been reported that oral and gut microbiomes interdependently regulate physiological functions and pathological processes. Oral-to-gut and gut-to-oral microbial transmissions can shape and/or reshape the microbial ecosystem in both habitats, eventually modulating pathogenesis of disease. However, the oral–gut microbial interaction in pathogenesis has been underappreciated to date. Here, we will highlight the oral–gut microbiome crosstalk and its implications in the pathogenesis of the gastrointestinal disease and cancer. Better understanding the role of the oral–gut microbiome axis in pathogenesis will be advantageous for precise diagnosis/prognosis and effective treatment.

Metaplastic Paneth Cells in Extra-Intestinal Mucosal Niche Indicate a Link to Microbiome and Inflammation

Paneth cells are residents of the intestinal epithelium. Abnormal appearance of Paneth cells has been widely documented in non-intestinal tissues within the digestive tract and even observed in non-gastrointestinal organs. Although metaplastic Paneth cells are part of the overarching pathology of intestinal metaplasia (IM), only a fraction of intestinal metaplastic lesions contain Paneth cells. We survey literature documenting metaplastic Paneth cells to gain insights into mechanism underlying their etiologic development as well as their potential relevance to human health. A synthesized view from this study suggests that the emergence of metaplastic Paneth cells at extra-intestinal mucosal sites likely represents a protective, anti-bacterial, and inflammatory response evoked by an altered microbial activity.

L-carnitine reduces acute lung injury in experimental biliary obstruction

OBJECTIVES

To investigate the protective effects of L-carnitine (LC) on lungs in an experimental obstructive jaundice (OJ) model.

METHODS

This was conducted for 2 months between May 2011 and July 2011 at Suleyman Demirel University School of Medicine Experimental and Clinical Research Center, Isparta, Turkey. Thirty-eight Wistar-Albino rats with an average weight of 250-300 g were divided into 3 groups of control, OJ, and OJ + L-carnitine treatment (LCT). L-carnitine was injected intravenously into the tail vein at a dose of 50 mg/kg/day for 10 days to the LCT group. Animals were sacrificed 10 days later. Enzyme levels were measured in the lung tissue; malondialdehyde, myeloperoxidase (MPO), glutathione peroxidase (GSH-Px), catalase, and superoxide dismutase. Tumor necrosis factor-alfa, interleukin 6 (IL-6), IL-8, and C-reactive protein levels were studied in plasma samples. Histopathological changes in the lungs were examined. 

RESULTS

There was a decreased in GSH-Px, MPO, and IL-8 levels (p less than 0.05) in the LCT group. The histopathological examination showed that neutrophil leukocyte infiltration and edema formation decreased and destruction of lung parenchyma disappeared following the treatment with LC (p less than 0.05). 

CONCLUSION

L-carnitine has a protective effect against lung damage due to experimental obstructive jaundice, possibly by altering anticytokine and antioxidant activity, and by decreasing the neutrophil migration.

Bile deficiency induces changes in intestinal glucose absorption in mice

BACKGROUND

Biliary tract obstruction is a common clinical problem. In this study, we attempted to understand the change in intestinal glucose absorption after biliary tract obstruction.

METHODS

Experimental models of murine biliary duct ligation and external biliary drainage were established. Murine intestinal mucosal glucose absorption was examined with Ussing chambers according to the increase in the short-circuit current in vitro and blood glucose measurement after oral glucose in vivo. The protein expression of the sodium-glucose cotransporter (SGLT1) and the facilitated glucose transporter, member 2 (GLUT2) was analyzed by Western blot and immunohistochemistry.

RESULTS

The results from Ussing chamber experiments showed that duodenal mucosal glucose absorption levels were significantly higher in biliary duct ligation and biliary drainage mice than those in normal control mice at 1 and 2 weeks after the operation. Gastrointestinal bile acid administration almost reversed the elevated duodenal mucosal glucose absorption to the normal level in biliary drainage mice. The results from the experiments in vivo further confirmed that the glucose absorption increased in biliary duct ligation and biliary drainage mice. The protein expression levels of SGLT1 in the duodenal mucosae of both biliary duct ligation and biliary drainage mice were markedly higher than those in control mice, and the protein expression of GLUT2 was not significantly altered, compared with control mice.

CONCLUSION

Bile deficiency in the intestine upregulates the expression of intestinal mucosal SGLT1 and enhances intestinal mucosal glucose absorption capacity, which contributes to the understanding of intestinal physiologic function for patients with biliary duct obstruction and external biliary drainage.

Immune dysfunction in patients with obstructive jaundice before and after endoscopic retrograde cholangiopancreatography

This prospective observational study investigated monocyte cytokine responses to lipopolysaccharide (LPS) in patients with obstructive jaundice (OJ) before and after endoscopic biliary drainage. Dendritic cell (DC) subsets and their expression of co-stimulatory molecules were also studied. Forty patients with OJ and ten non-jaundiced patients with normal gastroscopy findings were recruited. Ten healthy volunteers provided control blood samples for immunological assays. Patients with OJ had blood and duodenal mucosa sampled at the time of endoscopic retrograde cholangiopancreatography (ERCP) and further blood sampled during the recovery phase. Monocyte cytokine responses to LPS, DC subsets and co-stimulatory molecule expression were compared with controls. Duodenal morphology and occludin expression were also assessed. Monocytes obtained before ERCP from jaundiced patients demonstrated reduced cytokine responses to endotoxin compared with controls (IL-1β: 2678 compared with 4631 pg/ml, P=0.04 and IL-6: 3442 compared with 6157 pg/ml, P=0.002). Monocytes from patients with malignancy had poorer responses to endotoxin than from those with benign OJ (IL-1β: 2025 compared with 3332 pg/ml, P=0.001). After ERCP, the secretion of inflammatory cytokines by monocytes obtained from jaundiced patients increased (IL-1β: 2150 compared with 2520 pg/ml, P=0.03 and IL-6: 2488 compared with 3250 pg/ml, P=0.01). Occludin expression (85 compared with 95%, P=0.004) and mean duodenal villus height (334 compared with 404 μm, P=0.03) were lower in jaundiced patients. Before biliary drainage, patients with OJ had a higher percentage of myeloid dendritic cells (mDCs) and greater mDC expression of CD40 (P=0.04) and CD86 (P=0.04). Monocytes from patients with OJ had lower proinflammatory cytokine secretion in response to LPS, an effect reversed following biliary drainage.

Spontaneous bacterial peritonitis: The clinical challenge of a leaky gut and a cirrhotic liver

Spontaneous bacterial peritonitis (SBP) is a frequent, life-threatening bacterial infection in patients with liver cirrhosis and ascites. Portal hypertension leads to increased bacterial translocation from the intestine. Failure to eliminate invading pathogens due to immune defects associated with advanced liver disease on the background of genetic predisposition may result in SBP. The efficacy of antibiotic treatment and prophylaxis has declined due to the spread of multi-resistant bacteria. Patients with nosocomial SBP and with prior antibiotic treatment are at a particularly high risk for infection with resistant bacteria. Therefore, it is important to adapt empirical treatment to these risk factors and to the local resistance profile. Rifaximin, an oral, non-absorbable antibiotic, has been proposed to prevent SBP, but may be useful only in a subset of patients. Since novel antibiotic classes are lacking, we have to develop prophylactic strategies which do not induce bacterial resistance. Farnesoid X receptor agonists may be a candidate, but so far, clinical studies are not available. New diagnostic tests which can be carried out quickly at the patient’s site and provide additional prognostic information would be helpful. Furthermore, we need tools to predict antibiotic resistance in order to tailor first-line antibiotic treatment of spontaneous bacterial peritonitis to the individual patient and to reduce mortality.

Bile deficiency induces changes in intestinal Cl(-) and HCO3 (-) secretions in mice

AIMS

Biliary tract obstruction is a common clinical lesion. However, the effect of biliary tract obstruction on intestinal secretion is poorly understood. In this study, we made an investigation on intestinal HCO3 (-) and Cl(-) secretions in an experimental model of murine biliary duct ligation.

METHODS

Murine intestinal mucosal HCO3 (-) and Cl(-) secretions were examined in vitro in Ussing chambers by pH-stat and short-circuit current (Isc ) techniques. The mRNA and protein expressions of the cystic fibrosis transmembrane conductance regulator (CFTR) and the Na(+) -K(+) -2Cl(-) cotransporter (NKCC1) were analysed by real-time PCR, western blot and immunohistochemistry.

RESULTS

Basal Cl(-) secretion and forskolin-stimulated duodenal and jejunal mucosal HCO3 (-) and Cl(-) secretions in mice with common biliary duct ligation were markedly elevated, compared with controls (P < 0.05 and P < 0.01). Further experiments showed that basal Cl(-) secretion and forskolin-stimulated duodenal and jejunal mucosal HCO3 (-) and Cl(-) secretions in mice with external bile drainage were also markedly elevated. CFTRinh -172 inhibited forskolin-stimulated HCO3 (-) and Cl(-) secretions. The mRNA and protein expression levels of CFTR and NKCC1 in the intestinal mucosa with both biliary duct ligation and external bile drainage were markedly higher than those in controls (P < 0.001). Bile acid administration restored the changes in function and expression of CFTR and NKCC1 in the intestinal mucosa.

CONCLUSION

Bile deficiency in the intestine up-regulates the expressions of intestinal mucosal CFTR and NKCC1 and enhances intestinal mucosal HCO3 (-) and Cl(-) secretion capacity, which contributes to the understanding of intestinal physiological function for patients with biliary duct obstruction.

Inhibition of Toll-like receptor 4 suppresses liver injury induced by biliary obstruction and subsequent intraportal lipopolysaccharide injection

The objective of this study was to elucidate the role of Toll-like receptor 4 (TLR4) in liver injury induced by biliary obstruction and subsequent intraportal lipopolysaccharide (LPS) infusion in rats. Biliary obstruction often leads to the development of bacterial translocation. Rats were subjected to either a sham operation (Sham group) or bile duct ligation for 7 days (BDL group). Seven days after each operation, LPS (0.5 μg) was injected through the ileocecal vein. In other experiments, rats that had undergone BDL were pretreated, before LPS challenge, with internal biliary drainage (Drainage group); intravenous TAK-242, a TLR4 inhibitor (TAK group); or intravenous GdCl3, a Kupffer cell deactivator (GdCl3 group). The expression of the TLR4 protein and the number of Kupffer cells in the liver were significantly increased in the BDL group compared with the Sham group. These changes were normalized after biliary drainage. The expression of TLR4 colocalized with Kupffer cells, which was confirmed by double immunostaining. Serum levels of liver enzymes and proinflammatory cytokines after intraportal LPS injection were significantly higher in the BDL group than in the Sham group. However, pretreatment with TAK-242 or GdCl3 strongly attenuated these changes to levels similar to those seen with biliary drainage. These results imply that blocking TLR4 signaling effectively attenuates liver damage to the same level as that observed with biliary drainage in rats with BDL and subsequent intraportal LPS infusion. TAK-242 treatment may be used for patients who are susceptible to liver damage by biliary obstruction and endotoxemia.

Gut microbiota dysbiosis and bacterial community assembly associated with cholesterol gallstones in large-scale study

Background

Elucidating gut microbiota among gallstone patients as well as the complex bacterial colonization of cholesterol gallstones may help in both the prediction and subsequent lowered risk of cholelithiasis. To this end, we studied the composition of bacterial communities of gut, bile, and gallstones from 29 gallstone patients as well as the gut of 38 normal individuals, examining and analyzing some 299, 217 bacterial 16S rRNA gene sequences from 120 samples.

Results

First, as compared with normal individuals, in gallstone patients there were significant (P < 0.001) increases of gut bacterial phylum Proteobacteria and decreases of three gut bacterial genera, Faecalibacterium, Lachnospira, and Roseburia. Second, about 70% of gut bacterial operational taxonomic units (OTUs) from gallstone patients were detectable in the biliary tract and bacteria diversity of biliary tract was significantly (P < 0.001) higher than that of gut. Third, analysis of the biliary tract core microbiome (represented by 106 bacteria OTUs) among gallstone patients showed that 33.96% (36/106) of constituents can be matched to known bacterial species (15 of which have publicly available genomes). A genome-wide search of MDR, BSH, bG, and phL genes purpotedly associated with the formation of cholesterol gallstones showed that all 15 species with known genomes (e.g., Propionibacterium acnes, Bacteroides vulgates, and Pseudomonas putida) contained at least contained one of the four genes. This finding could potentially provide underlying information needed to explain the association between biliary tract microbiota and the formation of cholesterol gallstones.

Conclusions

To the best of our knowledge, this is the first study to discover gut microbiota dysbiosis among gallstone patients, the presence of which may be a key contributor to the complex bacteria community assembly linked with the presence of cholesterol gallstones. Likewise, this study also provides the first large-scale glimpse of biliary tract microbiota potentially associated with cholesterol gallstones. Such a characterization of the biliary tract core microbiome has potentially important biological and medical implications regarding the role of bacteria in the formation cholesterol gallstones.

Evaluation of postmortem bacterial migration using culturing and real-time quantitative PCR

Postmortem bacteriology can be a valuable tool for evaluating deaths due to bacterial infection or for researching the involvement of bacteria in various diseases. In this study, time-dependent postmortem bacterial migration into liver, mesenteric lymph node, pericardial fluid, portal, and peripheral vein was analyzed in 33 autopsy cases by bacterial culturing and real-time quantitative polymerase chain reaction (RT-qPCR). None suffered or died from bacterial infection. According to culturing, pericardial fluid and liver were the most sterile samples up to 5 days postmortem. In these samples, multigrowth and staphylococci were not or rarely detected. RT-qPCR was more sensitive and showed higher bacterial positivity in all samples. Relative amounts of intestinal bacterial DNA (bifidobacteria, bacteroides, enterobacter, clostridia) increased with time. Sterility of blood samples was low during the studied time periods (1-7 days). The best postmortem microbiological sampling sites were pericardial fluid and liver up to 5 days after death.

Influence of prophylactic probiotics and selective decontamination on bacterial translocation in patients undergoing pancreatic surgery: a randomized controlled trial

Bacterial translocation (BT) is suspected to play a major role in the development of infections in surgical patients. However, the clinical association between intestinal barrier dysfunction, BT, and septic morbidity has remained unconfirmed. The objective of this study was to study BT in patients undergoing major abdominal surgery and the effects of probiotics, selective decontamination of the digestive tract (SDD), and standard treatment on intestinal barrier function. In a randomized controlled setting, 30 consecutive patients planned for elective pylorus-preserving pancreaticoduodenectomy (PPPD) were allocated to receive perioperatively probiotics, SDD, or standard treatment. To assess intestinal barrier function, intestinal fatty acid-binding protein (mucosal damage) and polyethylene glycol recovery (intestinal permeability) in urine were measured perioperatively. BT was assessed by real-time polymerase chain reaction and multiplex ligation-dependent probe amplification (MLPA) in mesenteric lymph nodes (MLNs) harvested early (baseline control) and at the end of surgery ("end-of-surgery" MLNs, after 3h in PPPD patients). Polymerase chain reaction detected bacterial DNA in 18 of 27 end-of-surgery MLNs and in 13 of 23 control MLNs (P = 0.378). Probiotics and SDD had no significant effect on the number of positive MLNs or the change in bacterial DNA during operation. Multiplex ligation-dependent probe amplification analysis showed significantly increased expression of only 4 of 30 inflammatory mediator-related genes in end-of-surgery compared with early sampled MLN (P < 0.05). Polyethylene glycol recovery was unaffected by operation, probiotics and SDD as compared with standard treatment. Intestinal fatty acid-binding protein levels were increased shortly postoperatively only in patients treated with SDD (P = 0.02). Probiotics and SDD did not influence BT, intestinal permeability, or inflammatory mediator expression. Bacterial translocation after abdominal surgery may be part of normal antigen-sampling processes of the gut.

Protection against increased intestinal permeability and bacterial translocation induced by intestinal obstruction in mice treated with viable and heat-killed Saccharomyces boulardii

BACKGROUND

There are substantial evidences suggesting that probiotics can protect the gastrointestinal tract against inflammatory or infectious episodes. The effects of oral treatment with viable or heat-killed cells of Saccharomyces boulardii (Sb) on bacterial translocation, intestinal permeability, histological aspect of the ileum, and some immunological parameters were evaluated in a murine intestinal obstruction (IO) model.

RESULTS

Bacterial translocation and intestinal permeability in the IO group were significantly higher when compared to a Sham group (p < 0.05). Pretreatment with both viable and heat-killed S. boulardii prevented these increases, and the data obtained for IO + Sb and IO + heat-killed Sb groups were similar to those observed in the Sham group (p > 0.05). Histological analysis showed preservation of the ileum mucosa in mice that received both forms of the yeast when compared to the lesions observed in the IO group. The levels of serum interleukin (IL)-10 and intestinal secretory immunoglobulin A (sIgA) were higher in the animals that received both yeast treatments when compared to those from IO and Sham groups.

CONCLUSION

Oral treatment with viable or heat-killed cells of S. boulardii maintained intestinal integrity and modulated the immune system in a murine IO model, preventing bacterial translocation and intestinal lesions.

Effects of glutamine and curcumin on bacterial translocation in jaundiced rats

AIM: To investigate the effect of curcumin on bacterial translocation and oxidative damage in an obstructive jaundice model and compare the results to glutamine, an agent known to be effective and clinically used.

METHODS: Twenty-four female Wistar-Albino rats, weighing 200-250 g, were randomly divided into three groups (8 in each group). After ligation of the common bile duct in all animals, Group I received oral normal saline, Group II received oral glutamine and Group III received oral curcumin for seven days. Blood samples via cardiac puncture, tissue samples (terminal ileum, liver and mesenteric lymph node) and peritoneal fluid were obtained from the animals at the time of death to investigate bacterial translocation and oxidative damage.

RESULTS: We observed that both glutamine and curcumin reduced bacterial translocation in blood, hepatocellular damage, plasma cytokine levels, oxidative tissue damage and apoptosis significantly compared to the control group. Additionally, glutamine showed protective effects on ileal epithelium and reduced villus atrophy.

CONCLUSION: On the basis of these findings, both curcumin and glutamine are thought to be effective in preventing or reducing bacterial translocation and oxidative damage in obstructive jaundice.

Gut Microbiota in Health and Disease

Gut microbiota is an assortment of microorganisms inhabiting the length and width of the mammalian gastrointestinal tract. The composition of this microbial community is host specific, evolving throughout an individual's lifetime and susceptible to both exogenous and endogenous modifications. Recent renewed interest in the structure and function of this “organ” has illuminated its central position in health and disease. The microbiota is intimately involved in numerous aspects of normal host physiology, from nutritional status to behavior and stress response. Additionally, they can be a central or a contributing cause of many diseases, affecting both near and far organ systems. The overall balance in the composition of the gut microbial community, as well as the presence or absence of key species capable of effecting specific responses, is important in ensuring homeostasis or lack thereof at the intestinal mucosa and beyond. The mechanisms through which microbiota exerts its beneficial or detrimental influences remain largely undefined, but include elaboration of signaling molecules and recognition of bacterial epitopes by both intestinal epithelial and mucosal immune cells. The advances in modeling and analysis of gut microbiota will further our knowledge of their role in health and disease, allowing customization of existing and future therapeutic and prophylactic modalities.

Diagnosis and management of acute cholangitis

Bacterial infection that occurs in the setting of biliary obstruction can lead to acute cholangitis, a condition characterized by fever, abdominal pain and jaundice. Choledocholithiasis is the most common cause of acute cholangitis and is often associated with bacterial infection and colonization in addition to biliary obstruction. Iatrogenic introduction of bacteria into the biliary system most commonly occurs during endoscopic retrograde cholangiopancreatography in patients with biliary obstruction. The majority of patients with acute cholangitis respond to antibiotic therapy, but endoscopic biliary drainage is ultimately required to treat the underlying obstruction. Acute cholangitis is often diagnosed using the clinical Charcot triad criteria; however, recommendations from an international consensus meeting in Tokyo produced the most comprehensive recommendations for the diagnosis and management of acute cholangitis. These guidelines enable a more accurate diagnosis of acute cholangitis than do earlier methods, and they facilitate the classification of disease as mild, moderate or severe. Although these guidelines represent a notable advance toward defining a universally accepted consensus for the definition of acute cholangitis, they have several limitations. This Review discusses current recommendations for the diagnosis of acute cholangitis and addresses the advantages and disadvantages of different modalities for the treatment of this disease.

Pretreatment with arginine preserves intestinal barrier integrity and reduces bacterial translocation in mice

OBJECTIVE

To evaluate the effects of arginine on intestinal barrier integrity and bacterial translocation (BT) in mice undergoing intestinal obstruction.

METHODS

Mice were divided into 3 groups, treated for 7 d before surgical intervention with isocaloric and isoprotein diets. The ARG group received a diet containing 2% arginine, the IO (intestinal obstruction) and Sham groups, standard chow diet. On the eighth day of treatment, all animals received diethylenetriamine pentaacetic acid (DTPA) solution labeled with 99mTechnetium (99mTc-DTPA) by gavage for intestinal permeability analysis. After 90 min, the animals were anesthetized and the terminal ileum ligated. The Sham group only underwent laparotomy. After 4, 8, and 18 h, blood was collected for radioactivity determination. Samples of ileum were collected 18 h after surgery for histological analysis. In another set of animals, BT was evaluated. After 7 d of treatment, all animals received 10(8) CFU/mL of 99mTc-E.coli by gavage; 90 min later they were submitted to the surgical procedure described above. BT was determined by the uptake of 99mTc-E.coli in blood, mesenteric lymph nodes, liver, spleen, and lungs, assessed 18 h after the surgery.

RESULTS

The intestinal permeability and BT were higher in the IO group when compared with the Sham group (P < 0.05). Arginine supplementation reduced intestinal permeability and BT to physiologic levels. Histological analysis showed mucosal ileum preservation in animals treated with arginine.

CONCLUSION

Arginine was able to preserve barrier integrity, thus reducing BT.

Magnetic resonance imaging detects intestinal barrier dysfunction in a rat model of acute mesenteric ischemia/reperfusion injury

OBJECTIVES

To develop an in vivo intestinal permeability assay applying magnetic resonance imaging (MRI) to monitor real-time gut barrier defects in animal models of acute mesenteric ischemia/reperfusion (I/R) insult.

MATERIALS AND METHODS

Twenty Wistar rats were divided to 2 groups for I/R challenge or sham controls. I/R rats received occlusion of superior mesenteric artery for 20 minutes and reperfusion for 1 hour. Sham-operation controls received laparotomy without manipulation of artery. To assess gut permeability, a 10-cm jejunal sac was created distal to the ligament of Treitz in both groups of rats after laparotomy, and a contrast agent (gadodiamide) was injected into the lumen of the ligated intestinal sac. The signals produced by gadodamide in the liver, kidney, and plasma before and after the start of reperfusion were examined by 1.5 Tesla MRI (GE Signa Excite), and the increment of signal-to-noise ratio (SNR) in these organs that parallels the luminal-to-serosal flux rate of the probe was used as an indicator of gut permeability. At the end of procedures, jejunal tissues and mucosal scrapings were collected for histologic examination and Western blotting for epithelial tight junctional proteins. Moreover, liver and spleen homogenates were cultured on fresh blood agar plates to measure the bacterial colony-forming units per gram of tissue.

RESULTS

In I/R rats, disrupted villous structure and decreased epithelial tight junctional expression were seen in the jejunum associated with massive enteric bacterial translocation to the liver and spleen. The SNR in the liver of I/R rats was higher than sham controls (2.65 +/- 0.56 vs. 0.65 +/- 0.26, P < 0.01) at 15 minutes postreperfusion. Elevation of SNR in the kidney was also found in I/R rats compared with sham controls (11.61 +/- 2.07 vs. 3.06 +/- 1.15, P < 0.05). The plasma gadodiamide concentration in I/R rats was significantly increased compared with sham controls (0.220 +/- 0.044 vs. 0.006 +/- 0.004 mM, P < 0.01) at 15 minutes postreperfusion.

CONCLUSIONS

This novel MRI-based intestinal permeability assay has shown a significant increase in the signal intensity in liver, kidney, and plasma samples that correlated with mucosal barrier defects in experimental models of acute mesenteric I/R.

LPS-binding protein mediates LPS-induced liver injury and mortality in the setting of biliary obstruction

It is generally accepted that low levels of lipopolysaccharide (LPS)-binding protein (LBP) augment the cell's response to LPS, whereas high levels of LBP have been shown to inhibit cell responses to LPS. Clinical studies and in vitro work by our group have demonstrated that, in the setting of liver disease, increased or acute-phase levels of LBP may actually potentiate rather than inhibit an overwhelming proinflammatory response. Therefore, in the present studies we sought to determine the role of acute-phase LBP in mediating morbidity and mortality in animals challenged with LPS in the setting of biliary obstruction. Using LBP-deficient mice and LBP blockade in wild-type mice, we demonstrate that high levels of LBP are deleterious in the setting of cholestasis. Following biliary obstruction and intraperitoneal LPS challenge, hepatic injury, hepatic neutrophil infiltration, and mortality were significantly increased in animals with an intact LBP acute-phase response. Kupffer cell responses from these animals demonstrated a significant increase in several inflammatory mediators, and Kupffer cell-associated LBP appears to be responsible for these differences, at least in part. Our results indicate that the role of LBP signaling in inflammatory conditions is complex and heterogeneous, and elevated levels of LBP are not always protective. Increased LBP production in the setting of cholestatic liver disease appears to be deleterious and may represent a potential therapeutic target for preventing overwhelming inflammatory responses to LPS in this setting.

Approach to the patient who has suspected acute bacterial cholangitis

Table 4 gives summary recommendations concerning the major decisions that are related to the diagnosis and management of suspected acute bacterial cholangitis. All of these decisions have to be made within the context of disease severity, degree of diagnostic uncertainty, and associated comorbidity. Although these recommendations are based on evidence, there are few randomized controlled trials. Antibiotics that cover gram negatives and anaerobes, along with fluid and electrolyte correction, frequently stabilize the patient. Imaging studies frequently confirm the diagnosis and identify the location and etiology of the obstruction. With or without a definitive diagnosis, ERCP or PTC can be done emergently to establish drainage to control sepsis. Although endoscopic and percutaneous drainage techniques have lower morbidity and mortality than does emergent surgical decompression, optimal management of this potentially life-threatening condition requires close cooperation between the gastroenterologist, radiologist, and surgeon.