Reticulo-endothelial function in obstructive jaundice

Loss of bile salt export pump aggravates lipopolysaccharide-induced liver injury in mice due to impaired hepatic endotoxin clearance

BACKGROUND AND AIMS

Lipopolysaccharide (LPS) clearance is delayed in cholestatic liver diseases. While compromised clearance by Kupffer cells (KCs) is involved, the role of LPS uptake into hepatocytes and canalicular excretion remains unclear.

APPROACH AND RESULTS

Wild-type (WT) and bile salt export pump (Bsep) knockout (KO) mice were challenged i.p. with LPS. Liver injury was assessed by serum biochemistry, histology, molecular inflammation markers, and immune cell infiltration. LPS concentrations were determined in liver tissue and bile. Subcellular kinetics of fluorescently labeled LPS was visualized by intravital two-photon microscopy, and the findings in Bsep KO mice were compared to common bile duct-ligated (BDL) and multidrug resistance protein 2 (Mdr2) KO mice. Changes in gut microbiota composition were evaluated by 16S ribosomal RNA gene amplicon sequencing analysis. Bsep KO mice developed more pronounced LPS-induced liver injury and inflammatory signaling, with subsequently enhanced production of proinflammatory cytokines and aggravated hepatic immune cell infiltration. After LPS administration, its concentrations were higher in liver but lower in bile of Bsep KO compared to WT mice. Intravital imaging of LPS showed a delayed clearance from sinusoidal blood with a basolateral uptake block into hepatocytes and reduced canalicular secretion. Moreover, LPS uptake into KCs was reduced. Similar findings with respect to hepatic LPS clearance were obtained in BDL and Mdr2 KO mice. Pretreatment with the microtubule inhibitor colchicine inhibited biliary excretion of LPS in WT mice, indicating that LPS clearance is microtubule-dependent. Microbiota analysis showed no change of the gut microbiome between WT and Bsep KO mice at baseline but major changes upon LPS challenge in WT mice.

CONCLUSIONS

Absence of Bsep and cholestasis in general impair LPS clearance by a basolateral uptake block into hepatocytes and consequently less secretion into canaliculi. Impaired LPS removal aggravates hepatic inflammation in cholestasis.

Quantitative evaluation of the reticuloendothelial system function with dynamic MRI

PURPOSE

To evaluate the reticuloendothelial system (RES) function by real-time imaging blood clearance as well as hepatic uptake of superparamagnetic iron oxide nanoparticle (SPIO) using dynamic magnetic resonance imaging (MRI) with two-compartment pharmacokinetic modeling.

MATERIALS AND METHODS

Kinetics of blood clearance and hepatic accumulation were recorded in young adult male 01b74 athymic nude mice by dynamic T2* weighted MRI after the injection of different doses of SPIO nanoparticles (0.5, 3 or 10 mg Fe/kg). Association parameter, Kin, dissociation parameter, Kout, and elimination constant, Ke, derived from dynamic data with two-compartment model, were used to describe active binding to Kupffer cells and extrahepatic clearance. The clodrosome and liposome were utilized to deplete macrophages and block the RES function to evaluate the capability of the kinetic parameters for investigation of macrophage function and density.

RESULTS

The two-compartment model provided a good description for all data and showed a low sum squared residual for all mice (0.27±0.03). A lower Kin, a lower Kout and a lower Ke were found after clodrosome treatment, whereas a lower Kin, a higher Kout and a lower Ke were observed after liposome treatment in comparison to saline treatment (P<0.005).

CONCLUSION

Dynamic SPIO-enhanced MR imaging with two-compartment modeling can provide information on RES function on both a cell number and receptor function level.

Cytokine response to portal endotoxaemia and neutrophil stimulation in obstructive jaundice

INTRODUCTION

An exaggerated proinflammatory response to endotoxaemia can occur in obstructive jaundice. The aims of this study were to determine the hepatic proinflammatory and anti-inflammatory cytokine response to endotoxaemia in experimental biliary obstruction and to determine the source of interleukin-6 (IL-6) using immunohistochemistry.

METHODOLOGY

Male Wistar rats were randomized into three groups: bile duct ligation (BDL), sham operation, and control groups. They were weighed before surgery and after 1 week. On day 8, hepatic perfusion was performed with endotoxin (Escherichia coli 0111:B4). Serial samples of blood, effluent, and influent perfusate were analyzed for proinflammatory and anti-inflammatory cytokines. Ultrastructural assessment of sections of the liver was performed.

RESULTS

BDL animals lost weight in the first week compared with the sham and the control animals that gained weight. Liver function tests were elevated in the BDL group. Effluent biochemistry did not reveal liver injury as a result of perfusion. Ultrastructurally, there was no evidence of liver injury, with only active Kupffer cells, preservation of liver architecture, and minimal liver injury being detected. Serum tumor necrosis factor-α was not detected in any group before perfusion; however, serum IL-6 was higher in the BDL group. Portal endotoxaemia resulted in an increase in tumor necrosis factor-α, IL-6, and IL-10 in the BDL group. Fluorescence immunohistochemistry demonstrated IL-6 in the sinusoidal spaces and the cytoplasm of Kupffer cells.

CONCLUSION

There is an exaggerated proinflammatory and anti-inflammatory cytokine response to portal endotoxaemia in animals with jaundice compared with the sham group.

Decreased hepatic peroxisome proliferator-activated receptor-γ contributes to increased sensitivity to endotoxin in obstructive jaundice

AIM: To investigate the role of hepatic peroxisome proliferator-activated receptor-γ (PPAR-γ) in increased susceptibility to endotoxin-induced toxicity in rats with bile duct ligation during endotoxemia.

METHODS: Male Sprague-Dawley rats were subjected to bile duct ligation (BDL). Sham-operated animals served as controls. DNA binding were determined by polymerase chain reaction, Western blotting analysis, and electrophoretic mobility shift assay, respectively. BDL and sham-operated rats received a non-lethal dose of intraperitoneal lipopolysaccharide (LPS) injection (3 mg/kg, i.p.). Additionally, the potential beneficial effects of the PPAR-γ agonist rosiglitazone were determined in BDL and sham-operated rats treated with a non-lethal dose of LPS. Survival was assessed in BDL rats treated with a non-lethal dose of LPS and in sham-operated rats treated at a lethal dose of LPS (6 mg/kg, i.p.).

RESULTS: PPAR-γ activity in rats undergoing BDL was significantly lower than in the sham-controls. Hepatic PPAR-γ gene expression was downregulated at both the mRNA and protein levels. In a parallel group, serum levels of pro-inflammatory cytokines were nearly undetectable in the sham-operated rats. When challenged with a non-lethal dose of LPS (3 mg/kg), the BDL rats had approximately a 2.4-fold increase in serum IL-6, a 2.7 fold increase in serum TNF-α, 2.2-fold increase in serum IL-1 and 4.2-fold increase in serum ALT. The survival rate was significantly lower as compared with that in sham-operated group. Additionally, rosiglitazone significantly reduced the concentration of TNF-α, IL-1β, IL-6 and ALT in sham-operated rats, but not in BDL rats, in response to LPS (3 mg/kg). Also, the survival was improved by rosiglitazone in sham-operated rats challenged with a lethal dose of LPS, but not in BDL rats, even with a non-lethal dose of LPS (3 mg/kg).

CONCLUSION: Obstructive jaundice downregulates hepatic PPAR-γ expression, which in turn may contribute to hypersensitivity towards endotoxin.

Complications of the extrahepatic biliary surgery in companion animals

Surgery of the biliary tract is demanding and is associated with several potentially life-threatening complications. Veterinarians face challenges in obtaining accurate diagnosis of biliary disease, surgical decision-making, surgical hemostasis and bile peritonitis. Intensive perioperative monitoring is required to achieve early recognition of common postoperative complications. Proper treatment and ideally, avoidance of surgical complications can be achieved by gaining a clear understanding physiology, anatomy, and the indications for hepatobiliary surgery.

Pulmonary phagocyte depression induced by an acid or alkaline solution in a rat model of peritonitis

BACKGROUND

Peritonitis is a surgical problem with a high mortality rate attributable to various complications, including respiratory infection. This complication is more common under certain conditions reflective of the origin of peritonitis, suggesting that the composition of the peritoneal fluid exerts an influence on the intensity of the macrophage and peritoneal response. To establish a correlation among macrophage function, absorption of bacteria from the peritoneal cavity, and the pH of the peritoneal fluid, we carried out this study.

METHODS

Thirty female Wistar rats were divided into three equal groups, all of which received infusions of 0.9% saline by parietal puncture. In group A (control), the saline pH was 7.0; in group B, it was 2.5; and in group C, it was 8.5. After 40 min, 0.25 mL of a suspension containing 10(11) colony-forming units of (99m)Tc-labeled Escherichia coli was infused by the same route. After another 40 min, samples of vena caval blood, spleen, liver, and lung were removed; the radioactivity was counted; bacterial absorption was determined; and the proportional radioactivity/g of tissue was calculated. The values were compared among the groups by the Student t-test, with the level of significance set at p < 0.05.

RESULTS

There was significantly greater bacterial absorption in group B than in group C (p = 0.004) but no differences in the numbers of bacteria in the liver and spleen. Bacteria were significantly more numerous in the peripheral blood in group B than in groups A and C (p = 0.04 for both). Pulmonary phagocytosis was significantly reduced in group B compared with group A (p = 0.008) and group C (p = 0.005).

CONCLUSION

Peritonitis associated with acidic conditions in the peritoneal cavity is correlated with a reduction in pulmonary phagocytosis and an increase in the numbers of nonphagocytized bacteria in the peripheral blood, possibly representing a direct or indirect cause of the higher incidence of pneumonia and sepsis in these individuals.

Biliary obstruction selectively expands and activates liver myeloid dendritic cells

Obstructive jaundice is associated with immunologic derangements and hepatic inflammation and fibrosis. Because dendritic cells (DCs) play a major role in immune regulation, we hypothesized that the immunosuppression associated with jaundice may result from the functional impairment of liver DCs. We found that bile duct ligation (BDL) in mice expanded the myeloid subtype of liver DCs from 20 to 80% of total DCs and increased their absolute number by >15-fold. Liver myeloid DCs following BDL, but not sham laparotomy, had increased Ag uptake in vivo, high IL-6 secretion in response to LPS, and enhanced ability to activate T cells. The effects of BDL were specific to liver DCs, as spleen DCs were not affected. Expansion of liver myeloid DCs depended on Gr-1(+) cells, and we implicated monocyte chemotactic protein-1 as a potential mediator. Thus, obstructive jaundice selectively expands liver myeloid DCs that are highly functional and unlikely to be involved with impaired host immune responses.

Effect of vitamin A on the CD44 expression in the small intestine of rats with obstructive jaundice

HYPOTHESIS

In this study, the influence of obstructive jaundice on the CD44 expression in the rat small intestine and the alterations of this CD44 expression by vitamin A given intraperitoneally (200 IU/g/day) are evaluated.

MATERIALS AND METHODS

In a prospective animal model study, 32 Sprague-Dawley rats were randomized into four groups: group A rats (n = 8) underwent sham operation and were given daily saline intraperitoneally for 2 weeks (sham + saline); group B animals (n = 8) underwent sham operation and were given daily vitamin A intraperitoneally for 2 weeks (sham + vitamin A); group C rats (n = 8) underwent common bile duct ligation and were given daily saline intraperitoneally for 2 weeks (obstructive jaundice + saline), and group D animals (n = 8) underwent common bile duct ligation and were given daily vitamin A intraperitoneally for 2 weeks (obstructive jaundice + vitamin A). After 2 weeks, standardized jejunum and ileum segments were harvested from all animals. The expression of CD44 on the cell surface was evaluated immunohistochemically. Comparisons among the four groups were done.

RESULTS

The plasma bilirubin, aspartate transaminase, alanine transaminase, alkaline phospatase, and gamma-glutamyltransferase levels in groups C and D (obstructive jaundice groups) were higher than those in groups A and B (sham groups; p < 0.05). There was no difference between groups A and B (sham groups) with regard to the number of cells expressing surface CD44 in jejunum and ileum. When groups A and B were compared with group C (obstructive jaundice + saline) animals, the number of cells expressing surface CD44 was significantly decreased in both jejunum and ileum in group C. The difference between sham groups (A and B) and group C was found to be significant (p < 0.05). When group D (obstructive jaundice + vitamin A) was compared with group C (obstructive jaundice + saline), the number of cells expressing surface CD44 was significantly increased in jejunum and ileum in group D animals (p < 0.05), higher than in the sham groups (A and B). The difference between group D and sham groups (A and B) was found to be significant (p < 0.05).

CONCLUSION

Obstructive jaundice for 2 weeks significantly decreased the CD44 expression in the rat small intestine. We found that daily intraperitoneal administration of vitamin A in rats with obstructive jaundice for 2 weeks significantly restored the impaired CD44 expression.

Alterations of tumor necrosis factor-alpha and interleukin 6 production and activity of the reticuloendothelial system in experimental obstructive jaundice in rats

BACKGROUND

Immunological changes are well recognised in obstructive jaundice. The aim of this study was to monitor plasma tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) levels in rats with obstructive jaundice.

METHODS

The ability of splenocytes and peritoneal exudate cells (PEC) to produce these cytokines both spontaneously and on induction with lipopolysaccharide (LPS), was compared in rats with and without obstructive jaundice (OJ). The activity of the reticuloendothelial system (RES) was also measured.

RESULTS

Serum cytokine levels in OJ rats were higher than in control rats. PEC cultures produced significantly more IL-6, compared with control rats, declining thereafter. TNF-alpha activity in the splenocyte cultures of OJ rats was also higher than in the control group. Pronounced differences were found in the ability to produce TNF-alpha by PEC, i.e., TNF-alpha production was much stronger on day 7 in OJ rats than in controls. On day 14 TNF-alpha production was much lower and the spontaneous response was equal to the LPS-induced one. On day 21 the cells of OJ rats partially regained the ability to produce TNF-alpha RES activity of OJ rats was significantly suppressed in the liver and spleen, whereas the phagocytic activity in the lungs was elevated.

CONCLUSION

We have demonstrated that the immune reactivity of OJ rats, initially elevated, underwent subsequent depression. The study also revealed a major effect of the operation alone on the studied parameters.

Interleukin-1 receptor type I gene-deficient bile duct-ligated mice are partially protected against endotoxin

Cholestatic liver injury is associated with an increased susceptibility toward endotoxin-induced toxicity. To determine the role of interleukin 1 (IL-1) herein, extrahepatic cholestasis was induced by bile duct ligation (bdl) in IL-1 receptor type I gene-deficient (IL-1R(-/-)) mice, which are unresponsive to IL-1alpha and IL-1beta, and normal IL-1R(+/+) mice. Bdl elicited increases in hepatic IL-1alpha and IL-1beta messenger RNA (mRNA) and protein. Hepatocellular injury at 2 weeks after bdl was similar in IL-1R(-/-) and IL-1R(+/+) mice as shown by clinical chemistry and histopathology. Administration of endotoxin to cholestatic mice at 2 weeks after bdl was associated with enhanced cytokine release, more severe liver damage, and occurrence of death when compared with sham-operated mice. Endotoxin effects in sham-operated IL-1R(-/-) and IL-1R(+/+) mice were largely similar, but cholestatic IL-1R(-/-) mice were better protected against toxic effects of endotoxin, as reflected by lowered cytokine release, less profound liver injury, and reduced mortality. These data indicate that IL-1alpha and IL-1beta are produced in the liver after bdl, but that these cytokines do not play a significant role in cholestatic liver damage; however, endogenous IL-1 activity is an important denominator of enhanced endotoxin sensitivity that is observed during cholestasis induced by bdl.

Effect of 5-lipoxygenase inhibition on Kupffer cell clearance capacity in obstructive jaundiced rats

BACKGROUND

Obstructive jaundice is a common surgical problem. It may cause hepatic and Kupffer cell dysfunction. Previous studies demonstrated that 5-lipoxygenase inhibition prevents hepatic injury. However, its effect on Kupffer cell clearance capacity has not been determined yet.

MATERIALS AND METHODS

Rats were divided into four groups. In group 1 (sham control group), only bile duct dissection was performed. In other groups bile ducts were ligated and divided. In groups 1 and 2 saline, in group 3 ethanol, and in group 4 a 5-lipoxygenase inhibitor AA-861 was given intraperitoneally to the animals. Rats were sacrificed 14 days after the operations. Serum alkaline phosphatase, total bilirubin, and alanine aminotransferase levels were determined. Kupffer cell clearance capacity was measured using an in situ isolated hepatic perfusion technique. Hematoxylin-eosin-stained liver samples were evaluated under light microscope for histopathologic scoring.

RESULTS

Rats in the sham control group had significantly lower serum ALP and bilirubin values than those in the experimental groups with biliary obstruction. AA-861 administration significantly decreased serum ALT levels and histopathologic scores. There was no significant difference in ALT levels and histopathologic scores between the sham control and AA-861 groups. Kupffer cell clearance capacity was found to be significantly increased in the AA-861 group compared to other experimental groups with obstructive jaundice.

CONCLUSIONS

This study shows that leukotriene synthesis inhibition using AA-861 prevents hepatic damage and improves Kupffer cell clearance capacity in obstructive jaundiced rats. This may have significant implications for the management of patients with obstructive jaundice.

Endotoxin-induced mortality in bile duct-ligated rats after administration of reconstituted high-density lipoprotein

Cholestatic patients have substantial morbidity because of increased susceptibility to endotoxin (lipopolysaccharide [LPS]). Although reconstituted high-density lipoprotein (rHDL) can bind and neutralize LPS, cholestasis is associated with a near complete absence of HDL. Effects of rHDL infusion on the outcome of LPS-induced inflammatory responses in cholestatic rats were determined. Bile duct-ligated (BDL) and sham rats were treated with rHDL or saline and challenged with LPS. Distribution of cholesterol over the lipoprotein subclasses changed by ligation: levels in low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) were increased 2-fold and 5-fold, respectively, and were decreased in HDL 2-fold. rHDL treatment did not affect cholesterol distribution. LPS was mainly found in the HDL fraction, and ligation affected only levels of HDL-bound LPS (50% decrease; P<.05). Although rHDL infusion effectively normalized the lipoprotein-bound LPS distribution, it resulted in increased sensitivity (mortality: 88% in the ligation + rHDL group versus 44% in the ligation + saline group, 25% in the sham + saline group, and 0% in the sham + rHDL group, P <.05). In accordance with these results, plasma tumor necrosis factor (TNF) was significantly highest in the BDL + rHDL group at several hours after LPS challenge as well as the accumulation of LPS in the liver (P<.05). rHDL infusion leads to increased LPS-induced mortality in cholestatic rats. These results sharply contrast with the protective effects of rHDL suppletion in experimental endotoxemia in animals and human volunteers without biliary obstruction and suggest that there may be danger in administration of rHDL to cholestatic patients.

Factors predicting perioperative cytokine response in patients undergoing liver transplantation

OBJECTIVES

An exaggerated production of proinflammatory cytokines during liver transplantation stimulates the inflammatory process within the graft, and eventually promotes liver failure. This study was conducted to evaluate factors predicting perioperative response of proinflammatory cytokines during liver transplantation.

DESIGN

Prospective, consecutive entry study of liver transplant candidates.

SETTING

University hospital.

PATIENTS

Thirty liver transplant recipients.

INTERVENTIONS

Arterial blood samples were obtained perioperatively.

MEASUREMENTS

Interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha were measured by ELISA. Endotoxin was determined by a chromogenic endotoxin-specific method.

MAIN RESULTS

The peak concentrations of IL-1beta and IL-6 in the patients with complications were significantly higher than those in the patients without complications. The peak concentration of IL-1beta was significantly correlated with the level of bilirubin at admission and the intraoperative blood product requirement. The peak concentration of IL-6 was significantly correlated with the admission bilirubin and the intraoperative blood product requirement. A multivariate regression model revealed that the serum bilirubin and the intraoperative blood product requirement were the independent factors that influenced the peak concentration of IL-1beta or IL-6. The severely jaundiced patients had a significantly higher plasma concentration of endotoxin at the end of the anhepatic phase. In addition, there was a tendency for these patients to have a higher postoperative peak concentration of endotoxin.

CONCLUSIONS

Serum level of bilirubin may be a potent preoperative factor influencing perioperative cytokine response in patients undergoing liver transplantation. An enhanced perioperative response of endotoxin seen in severely jaundiced patients suggests the clinical implication of endotoxin removal during the anhepatic phase in liver transplant surgery.

Treatment with recombinant bactericidal/permeability-increasing protein to prevent endotoxin-induced mortality in bile duct-ligated rats

BACKGROUND

Operation in patients with obstructive jaundice is associated with substantial morbidity because of increased susceptibility to endotoxin (lipopolysaccharide) and the inflammatory cascade. Different interventions to reduce endotoxemia and cytokine induction, and resulting complications, have been studied. Bactericidal/permeability-increasing protein (BPI) is a naturally occurring endotoxin-binding protein produced in neutrophils. It binds endotoxin, neutralizing the activity and inhibiting cytokine production by mononuclear cells. In experimental endotoxemia in animals and in healthy human volunteers, BPI has shown a protective effect. The aim of this study was to determine whether BPI could protect against increased endotoxin sensitivity in rats with obstructive jaundice and reduce endotoxin-induced mortality.

STUDY DESIGN

Male Wistar rats were used. Intraperitoneal Escherichia coli 2mg/kg was given 1 week after sham operation or bile duct ligation (BDL). Three groups were studied: sham, BDL with placebo, and BDL with 5 mg/kg recombinant BPI21.

RESULTS

BDL rats were jaundiced (mean bilirubin 186 micromol/L; no difference between BDL rats without or with BPI). Bilirubin remained less than 1 micromol/L in sham-operated rats (p = 0.002). Endotoxin levels were 3.4pg/mL in sham controls and 3.1 pg/mL in BDL rats before administration of lipopolysaccharide (p = NS). Two hours after administration, levels were 615.4ng/mL in placebo BDL rats and 10 times less in BPI-treated BDL rats, at 60.2ng/mL (p=0.03). The same trend was found at 6 hours. At 24 hours, mortality was 1 of 6 in sham-operated rats (15%) versus 8 of 11 in untreated BDL rats (75%). BPI intervention reduced the death rate to 1 of 12 BDL rats (8%) (p = 0.003).

CONCLUSIONS

Intraperitoneal recombinant BPI21 in rats having BDL reduced endotoxin-induced mortality from 75% to 8%, a death rate comparable to that in nonjaundiced rats. BPI could be an interesting perioperative treatment in clinical obstructive jaundice.

Characterization of the Kupffer cell response to exogenous endotoxin in a rodent model of obstructive jaundice

BACKGROUND

Sepsis and endotoxaemia occur frequently in biliary obstruction. Impaired Kupffer cell endocytosis is implicated in these events. Tumour necrosis factor and interleukin 6, secreted by Kupffer cells, are important mediators of sepsis. Kupffer cell clearance of endotoxin and secretion of cytokines in experimental obstructive jaundice were investigated.

METHODS

Wistar rats were randomized to bile duct ligation, sham operation or control. Groups (n = 8) were studied 1 and 3 weeks after operation. Kupffer cell function was assessed using in situ hepatic perfusion.

RESULTS

Clearance of endotoxin was significantly depressed 1 week (median (interquartile range) 20.3 (10.5-27.1) per cent) and 3 weeks (22.1 (20.2-23.2) per cent) after bile duct ligation compared with that in respective sham animals (35.5 (29.9-41.6) and 40.9 (37.7-47.0) per cent) and controls (39.5 (37.3-46.8) per cent). Secretion of tumour necrosis factor was significantly greater 1 week (1113.7 (706.5-1436. 8) pg/ml) and 3 weeks (1118.2 (775.7-1484.1) pg/ml) following bile duct ligation compared with that in respective sham animals (114.3 (0-178.5) and 107.6 (63.7-166.4) pg/ml) and controls (0 (0-20.7) pg/ml). Interleukin 6 was not secreted by sham or control animals but was present in the perfusate from jaundiced animals at 1 and 3 weeks (52.5 (9.9-89.5) and 66.2 (60.2-193.1) pg/ml).

CONCLUSION

These data demonstrate simultaneous impairment of Kupffer cell clearance of endotoxin and increased secretion of proinflammatory cytokines in experimental obstructive jaundice. These diverse responses may contribute to the development of sepsis-related complications in biliary obstruction.

Review article: antibiotic prophylaxis for endoscopic retrograde cholangiopancreatography (ERCP)

This review examines the evidence for antibiotic prophylaxis in endoscopic retrograde cholangiopan-creatography (ERCP), and provides detailed advice about suitable antibiotic regimens in appropriate high-risk patients. Ascending cholangitis and infective endocarditis are potential complications of endoscopic ERCP. The pathophysiology of these two complications is quite separate and different sub-groups of patients require prophylaxis with appropriate antibiotic regimens. Ascending cholangitis results from bacterial infection of an obstructed biliary system, usually from enteric Gram-negative microorganisms, resulting in bacteraemia. There is incomplete drainage of the biliary system after ERCP in up to 10% of patients who require stenting. Antibiotics started in these patients will probably reduce the frequency of cholangitis by 80%. If antibiotics are restricted to this group, approximately 90% of all patients having an ERCP will avoid antibiotics, but 80% of cholangitic episodes will be prevented. Infective endocarditis may result from the bacteraemia caused at the time of the ERCP in patients with an abnormal heart valve. Antibiotic prophylaxis, in particular covering alpha-haemolytic streptococci, should be started before the procedure in this defined high-risk group.

Biliary decompression promotes Kupffer cell recovery in obstructive jaundice

BACKGROUND

Jaundiced patients undergoing surgical procedures have an increased risk of Gram negative sepsis with potential morbidity and mortality. Depressed Kupffer cell clearance capacity (KCCC) predisposes jaundiced patients to endotoxaemia and its sequelae. Biliary decompression remains the main therapeutic strategy in obstructive jaundice.

AIMS

This study investigates the efficacy of internal (ID) and external biliary drainage (ED) on KCCC in an experimental model of extrahepatic biliary obstruction.

METHODS

Adult male Wistar rats (250-300 g) were assigned to one of six groups: sham operated, where the bile duct was mobilised but not divided; bile duct ligation (BDL) for three weeks, and sham operated or BDL for three weeks followed by a second laparotomy and further 21 days of ID or ED, by way of choledochoduodenostomy or choledochovesical fistula respectively. KCCC was measured using an isolated hepatic perfusion technique with FITC labelled latex particles (0.75 mu) as the test probe. Plasma was assayed for bilirubin, endotoxin, and anticore glycolipid antibody (ACGA) concentrations.

RESULTS

Jaundiced rats had reduced KCCC (p < 0.001), increased concentrations of ACGA (p < 0.001), and endotoxin (p < 0.001) compared with controls. Biliary drainage for three weeks produced a recovery in KCCC and normalisation of endotoxin and ACGA concentrations, however, external drainage was less effective than ID (p < 0.01).

CONCLUSIONS

These data support the hypothesis that endotoxaemia and its mediated effects are integral in the pathophysiology of jaundice. Furthermore, a short period of internal biliary drainage is a useful therapeutic strategy in restoring Kupffer cell function and negating systemic endotoxaemia and consequent complications in biliary obstruction.

Mononuclear phagocyte activation and acute pancreatitis

Severe, acute pancreatitis is commonly associated with a systemic illness which may result in multiple organ failure. There is evidence that an aberrant immune response, involving increased secretion of proinflammatory cytokines from activated monocytes and mononuclear phagocytes, is responsible for another systemic illness--septic shock. Previous studies have investigated whether there is a correlation between plasma cytokine levels and severity of pancreatitis. However, these results may not reflect mononuclear phagocyte activation. In this paper, monocytes (collected from patients with severe pancreatitis) were cultured in vitro and secreted cytokine levels measured after 24 hours by ELISA. Secretion of tumour necrosis factor alpha, interleukin-6 and interleukin-8 was higher in cells taken from patients who later developed systemic complications. There was no difference in the secretion of interleukin-1 beta. The mechanism by which mononuclear phagocytes are activated in acute pancreatitis, and the role of genetic predisposition, are discussed.

Technetium 99m sulfur colloid scintigraphy to evaluate reticuloendothelial system function in dogs with portasystemic shunts

In a retrospective study, technetium 99m sulfur colloid scintigraphy was used to evaluate reticuloendothelial system function in 61 dogs with single congenital and 40 dogs with multiple acquired portasystemic shunts. Whole body reticuloendothelial function was measured by calculating the plasma clearance rate constant from a dynamic study of liver uptake of 99mTc sulfur colloid. Relative liver, spleen, and lung uptake, and a ratio of hepatic:extrahepatic uptake were measured on static equilibrium images. Results were compared with those of a group of 26 normal dogs. Compared with values for the group of normal dogs, the plasma clearance rate constant, relative liver uptake, and hepatic:extrahepatic uptake ratio were significantly decreased, and relative spleen and lung uptake were significantly increased in dogs with portasystemic shunts (P < .0001). The only significant difference between dogs with single congenital versus multiple acquired shunts was that the relative splenic uptake was higher in the former group (P < .0002). Based on these results, we concluded that dogs with portasystemic shunts have significantly impaired reticuloendothelial function. The primary cause of this dysfunction is likely a reduction in effective liver blood flow. Increases in spleen and lung reticuloendothelial activity did occur, but only partially compensated for the reduction of liver reticuloendothelial activity. Possible mechanisms for the increased spleen and lung uptake are discussed.

Experimental foreign-body infection in the biliary tract in rats

BACKGROUND

Biomaterials used for biliary drainage may potentially result in biomaterial-associated infections.

METHODS

Foreign-body infection in the biliary tract was investigated in rats. Rubber drain pieces were implanted in the biliary tract in rats for 1-4 weeks, followed by challenges with 10(2) to 10(4) colony-forming units (cfu) Escherichia coli injected into the common bile duct. The rate of infection was calculated, the bacterial growth in the biliary tract was observed over 72 h after challenges, and the opsonic activity in bile and in sera was assessed.

RESULTS

In the group with drain material, inocula as small as 10(2) cfu produced persisting infection in the common bile duct in 90% of animals, whereas the same number of E. coli infected only 30% of rats in the control and sham implantation groups (p < 0.01, chi-square test). Complement-mediated opsonic activity in bile of animals with implanted drain pieces gradually decreased with time, whereas opsonic activity in sera from the same animals remained unchanged.

CONCLUSIONS

Implants in the biliary tract impair local host defense, resulting in an increased susceptibility to microbial infection.

Modulation of immune function and weight loss by L-arginine in obstructive jaundice in the rat

Jaundiced surgical patients have a high incidence of postoperative complications. Many causative factors have been identified including cachexia and immune suppression. The amino acid L-arginine has anabolic and immunostimulatory properties. It was hypothesized that dietary supplementation with L-arginine would diminish the weight loss and immune suppression of obstructive jaundice. Sixteen male Wistar rats rendered jaundiced by bile duct ligation were allocated to two groups. The test group (n = 8) received drinking water supplemented with 1.8 percent L-arginine ad libitum and the control group (n = 8) received a solution of isonitrogenous glycine. Both groups had free access to standard chow. Body-weight, and fluid and food intake were recorded. After 21 days, delayed-type hypersensitivity to 2,4-dinitrofluorobenzene was assessed. Animals receiving L-arginine consumed more food than controls (mean(s.e.m.) 414(16) versus 360(13) g, P < 0.05) and lost less weight (mean(s.e.m.) proportion of initial body-weight lost 7.8(1.2) versus 14.8(1.4) percent, P < 0.05). The delayed-type hypersensitivity response was significantly greater in rats receiving L-arginine (mean(s.e.m.) increase in ear thickness 23.9(2.7) versus 9.4(2.1) percent, P < 0.05). In this animal model of obstructive jaundice dietary supplementation with L-arginine diminished both weight loss and immune suppression.

Study of plasma and red cell phospholipid fatty acids in extrahepatic cholestatic jaundice

The poor outcome in patients with extrahepatic cholestatic jaundice seems in some way related to reticuloendothelial dysfunction. Similar dysfunction can be caused by abnormal tissue phospholipid fatty acid patterns. Little is, however, known about such patterns in extrahepatic cholestatic jaundice. The phospholipid fatty acid patterns in 42 controls were compared with 42 patients with extrahepatic cholestatic jaundice. Many abnormalities were found. The general pattern was of a fall in polyunsaturated fatty acids and a rise in monounsaturated fatty acids, with a consequent fall in the double bond index (mean number of double bonds per fatty acid) showing an overall rise in saturation. All three major substrates for eicosanoid production were reduced in the jaundiced group. The changes seemed to be associated with jaundice itself, rather than the cause of the jaundice. The central roles of fatty acids in the determination of membrane function and in the provision of substrates of eicosanoid production, mean that these changes may explain some of the reticuloendothelial dysfunction found in extrahepatic cholestatic jaundice.

Inhibition of bacterial translocation in obstructive jaundice by muramyl tripeptide phosphatidylethanolamine in the rat

Obstructive jaundice is frequently associated with septic complications and enteric bacteria have been isolated from both the infectious focus and bile in jaundiced patients. The present study aimed to evaluate bacterial translocation and the influence of a macrophage-stimulant (muramyl tripeptide phosphatidylethanolamine) on bacterial translocation in obstructive jaundice. Male Sprague-Dawley rats were subjected to sham operation (n = 10) or common bile-duct ligation and transection (n = 35). Two weeks later, jaundiced animals received either physiological saline (n = 15), muramyl tripeptide phosphatidylethanolamine liposomes (n = 10) or placebo (empty) liposomes (n = 10) orally, while sham-operated rats received physiological saline, 48 h prior to evaluation of enteric bacterial translocation. Blood, bile and caecal contents were collected and cultured aerobically and anaerobically, as were tissue samples from the liver, spleen and mesenteric lymph nodes. Positive mesenteric lymph node cultures in animals with jaundice + saline (7/15; 47%) and jaundice + placebo liposomes (4/10; 40%) significantly differed (p < 0.05) from sham-operated animals (1/10; 10%) and muramyl tripeptide phosphatidylethanolamine treated animals (0/10). Caecal counts (CFU/g) of Escherichia coli, Lactobacilli and aerobic and microaerobic bacteria did not differ statistically among the groups, although the number of E. coli tended to be higher in jaundiced animals. Thus, liposomal muramyl tripeptide phosphatidylethanolamine inhibits bacterial translocation, probably by activating mucosal macrophages and enhancing reticuloendothelial system function in rats with biliary obstruction.

Evaluation of the maximal excretion rate of indocyanin green as a prognostic indicator in patients undergoing biliary decompression for obstructive jaundice

To assess the postoperative outcome of jaundiced patients and to select the optimal timing for surgical intervention, indocyanin green (ICG) concentrations in the bile were measured after biliary decompression in patients with obstructive jaundice. The maximal excretion rate of ICG in the bile was calculated as a function of time (ICG Bmax). Among 59 patients with positive ICG Bmax values, morbidity was 15.2% and postoperative hospital mortality was 3.3%. However, the morbidity and mortality in nine patients with values between -0.5 and 0 were 88.8 and 44.4%, respectively. The 13 patients with in ICG Bmax below -0.5 had a 76.9% morbidity and a 61.5% mortality. The patients with ICG Bmax values below 0 showed a significantly higher morbidity and mortality than positive ICG Bmax patients. In patients showing ICG Bmax values below -0.5, surgery is contraindicated despite intensive postoperative care. The ICG Bmax value improved according to the increasing effect of biliary decompression. The index is useful not only as a prognostic index in the early phase of biliary decompression but also as an index of bile secretory capacity at a given time. By means of time course measurement of this index, the suitable time for operation can be determined. The ICG Bmax is a useful and reliable indicator in the assessment of hepatobiliary functional reserve in jaundiced patients after biliary decompression and prior to further surgical intervention.

Effect of antitumour necrosis factor treatment on circulating tumour necrosis factor levels and mortality after surgery in jaundiced mice

Tumour necrosis factor (TNF) may play an important role in the increased incidence of complications after surgery in patients with obstructive jaundice. This study evaluated the effect of three different anti-TNF treatments, a monoclonal anti-TNF antibody (TN3), pentoxifylline and lactulose, on outcome after severe surgical trauma in mice with experimental biliary obstruction. Circulating serum TNF levels and mortality rate were monitored. Severe surgical trauma, such as renal ischaemia, in jaundiced mice resulted in increased levels of circulating TNF (3.5 ng/ml) and a high mortality rate (54 per cent). The three different anti-TNF treatments caused a significant reduction in postoperative levels of circulating TNF (TN3, P < 0.001; pentoxifylline, P < 0.01; lactulose, P < 0.05). Treatment with TN3 and pentoxifylline did not lead to a significantly reduced mortality rate (36 and 44 per cent respectively). Only lactulose treatment produced a significantly reduced mortality rate (7 per cent, P < 0.01). TNF is therefore not the only mediator responsible for death after surgery in jaundiced mice. Other mechanisms affected by lactulose are also involved.

Biliary drainage in obstructive jaundice: experimental and clinical aspects

Jaundiced patients undergoing invasive diagnostic and therapeutic procedures are at increased risk of complications and death. Despite the large number of clinical and experimental investigations carried out to identify relevant risk factors, no single parameter has been found to be consistently useful in predicting morbidity or mortality. Biliary decompression was initially employed by surgeons and subsequently by interventional radiologists. More recently, endoscopic retrograde cholangiopancreatography has provided an alternative route for decompression of the biliary tree and preliminary data using this method are encouraging. Although there are enthusiastic proponents of various therapeutic techniques, controlled trials have not been convincing in highlighting the benefits of biliary drainage or in determining the best approach. This article reviews the literature pertaining to this complex surgical problem; an attempt has been made to balance the advantages and disadvantages of biliary decompression as palliation and/or preliminary treatment for extrahepatic biliary obstruction.

Modification of reticuloendothelial function by muramyl dipeptide-encapsulated liposomes in jaundiced rats treated with biliary decompression

Rats with 2 weeks of biliary obstruction, with and without 1 week of concomitant biliary decompression relieving the jaundice, were treated with physiologic saline, free muramyl dipeptide (MDP), placebo liposomes, or liposome-encapsulated MDP. Reticuloendothelial system (RES) function was evaluated by blood clearance of intravenously injected 125I-labelled Escherichia coli. The corrected phagocytic index (alpha) after 1 week of biliary decompression returned to normal levels in animals treated with MDP liposomes, whereas RES function was impaired (P < 0.05) in all other jaundiced and biliary-decompressed groups. In the biliary-decompressed, MDP-liposome-treated group, hepatic uptake of radiolabelled bacteria was significantly higher (P < 0.05) and renal entrapment of bacteria was significantly lower (P < 0.05) than in all other jaundiced and biliary-decompressed groups. We conclude that treatment with MDP liposomes improves the otherwise impaired RES function in rats with biliary obstruction and biliary decompression.

Hepatic macrophage malfunction in rats with obstructive jaundice and its biological significance

The present study was designed to investigate the pathophysiology of obstructive jaundice by analyzing the function of hepatic macrophages and their role in immune responses and homeostasis in rats. The phagocytic index, determined by the rate of disappearance of 51Cr-endotoxin from the peripheral blood after intravenous injection, was increased in obstructive jaundice 2 weeks after bile duct ligation. The superoxide production of isolated hepatic macrophages and peripheral blood monocytes, measured by the superoxide dismutase inhibitable ferricytochrome c reduction method, was increased. Prostaglandin E2 release, measured by RIA, was markedly increased in rats with obstructive jaundice, but there was no significant difference in interleukin-1 release between jaundiced and control rats. The flow-cytometric analysis of surface molecules of hepatic macrophages showed decreased expression of interleukin-2 receptor in rats with obstructive jaundice. Thus, the functions of hepatic macrophages in rats with obstructive jaundice were impaired. This malfunction may disturb the immunoregulatory network and metabolism, although the exact implications of the altered function of hepatic macrophages have not yet been clarified.

Effect of biliary decompression on reticuloendothelial function in jaundiced rats

The recovery of reticuloendothelial system (RES) function following decompression of obstructive jaundice was studied using a rat model with bile duct ligation and side-to-side choledochoduodenostomy. Histopathological changes in the liver were still present 5 weeks after relief of jaundice, while results of liver function tests had returned to normal. RES function evaluated by the blood clearance and organ uptake of radiolabelled Escherichia coli using a corrected phagocytic index gradually returned to normal following biliary decompression. The severely impaired RES activity noted 1 week after operation may explain the increased incidence of sepsis and renal insufficiency in the early period after biliary surgery in jaundiced patients.

Impaired clearance and organ localization of Candida albicans in obstructive jaundice

Sepsis is a major cause of morbidity and mortality in infants with cholestatic jaundice. This may be attributed to altered host defense mechanisms. Fungal infection frequently occurs in immunocompromised patients. This study evaluates the effect of biliary obstruction on blood clearance and organ localization of radiolabeled viable Candida albicans. Male Sprague-Dawley rats (140 to 150 g) were placed in 2 groups. Group I (n = 30) were sham-operated controls. Group II (n = 90) underwent ligation and division of the distal common bile duct (CDL). At 1, 2, and 3 weeks following CDL, 10(7) cells/mL radiolabeled viable C albicans were injected via the tail vein. The final distribution of the organisms was calculated and expressed as the mean percent of radiolabeled organisms per gram and per total organ. Blood clearance of C albicans was similarly rapid in both groups. However, there was a significant decrease in the trapping of fungi by the rat liver Kupffer cells (20.3% +/- 7.9% v control 42.5% +/- 15%; P greater than .001), and increased pulmonary localization of bacteria 3 weeks following CDL (53.6% +/- 13.2% v control 41.4% +/- 6.4%). The significant decrease in liver trapping and increased lung localization of C albicans in CDL rats, may result in systemic reemergence of fungi and play a role in the susceptibility to fungal infection in jaundiced subjects.

Effects of relief of biliary obstruction on mononuclear phagocyte system function and cell mediated immunity

Obstructive jaundice causes depression of immune system function but it is unclear at present how rapidly immune function recovers after relief of biliary obstruction. To address this issue, we studied 218 Sprague-Dawley rats with common bile duct obstruction. Mononuclear phagocyte function, cell mediated immune function, portal-systemic shunt fraction, liver function tests, and liver histology were evaluated in normal (sham) rats, obstructed rats, and at weekly intervals after relief of biliary obstruction. Hepatic uptake of radiolabelled bacteria was 82 per cent in sham rats and 66 per cent in rats 21 days after CBD obstruction (P less than 0.05). Phagocytic activity returned to normal within 7 days after choledochoduodenostomy. Cell mediated immunity, measured by skin graft rejection, was significantly prolonged in the obstructed group (P less than 0.05) but had returned to normal 7 days after biliary diversion. Return of hepatocellular function, as measured by liver function tests, paralleled recovery of immune function. This study demonstrates prompt recovery of the immune system after internal biliary drainage for obstructive jaundice. This finding is in contrast to previous studies that demonstrated persistent immune suppression months after biliary diversion. These data may have implications concerning the usefulness of internal biliary drainage before surgery in patients with obstructive jaundice.

Prevention of postoperative renal dysfunction in patients with obstructive jaundice: a multicentre study of bile salts and lactulose

The role of preoperative lactulose and bile salts in the prevention of postoperative renal failure in patients with obstructive jaundice has been evaluated in a prospective randomized trial. One hundred and two patients undergoing surgery for obstructive jaundice (bilirubin greater than 100 mumols/l) were randomized into three groups: those receiving preoperative oral lactulose (n = 35), those receiving oral sodium deoxycholate (n = 32) and a control group of patients receiving no specific treatment (n = 35). All patients received intravenous fluids commencing the night before surgery. One patient in the control group and none in the treatment groups developed postoperative renal failure. Postoperative deterioration of renal function in patients with normal preoperative function was significantly more common in the control group than in the treatment groups (chi 2 = 8.1, d.f. = 2, P less than 0.02). The incidence of renal failure and impairment was lower in this control group than that reported in previous studies. This may be due to the introduction of adequate preoperative hydration. Additional protection occurs by the preoperative administration of either lactulose or sodium deoxycholate.

Impaired hepatic bacterial clearance is reversed by surgical relief of obstructive jaundice

Sepsis is a major cause of morbidity and mortality in infants with cholestatic jaundice. Previous studies have shown that biliary obstruction in rats causes a significant decrease in hepatic phagocytosis of viable Escherichia coli. This study tests this hypothesis and further evaluates whether the impaired function of the reticuloendothelial system of the liver (Kupffer cells) can be reversed by the relief of the biliary obstruction. Male Sprague-Dawley rats (weighing 140 to 150 g) were placed in three groups. Group I (n = 10) consisted of sham-operated controls. In Group II (n = 30), ligation and division of distal common bile duct (CDL) was performed. Group III (n = 30) underwent choledochoduodenostomy 2 weeks following ligation and division of common bile duct. At 1, 2, and 3 weeks following the operation, 10(9) 35S-radiolabeled viable E coli were injected intravenously via the tail vein. At 10 minutes, bacterial distribution in the liver, spleen, kidneys, and lungs was determined. Tissue samples (50 to 100 mg) from each organ were processed for liquid scintillation counting. The final distribution of bacteria was calculated from the input specific activity (dpm/bacteria) and expressed as the mean percentage of injected viable E coli per gram of tissue and per total organ weight. There was a significant decrease in the trapping of bacteria by the liver's Kupffer cells in rats in group II, at 2 and 3 weeks following CDL (45.0% +/- 14.0% and 15.1% +/- 4.9%, respectively, v controls 75.9% +/- 13.7%; P less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)

Contribution of portal systemic shunt to Kupffer cell dysfunction in obstructive jaundice

Previous animal models of biliary tract obstruction have shown that hepatic phagocytic activity is impaired secondary to Kupffer cell dysfunction. Biliary tract obstruction leads to portal hypertension and an associated portal systemic shunt. Forty-eight Sprague-Dawley rats were studied to determine the contribution of portal systemic shunt to Kupffer cell dysfunction after 21 days of obstructive jaundice or sham operation. Liver uptake of radiolabeled Escherichia coli decreased from 76.1 +/- 1.4% (sham) to 63.1 +/- 6.1% in the common duct ligation (CDL) rats (P less than 0.05); lung uptake increased from 4.0 +/- 0.6% (sham) to 20.2 +/- 4.5 (CDL) (P less than 0.05). Portal systemic shunt, determined using radioactive microspheres, increased from 2.0 +/- 1.0% (sham) to 46.6 +/- 13.1% (CDL), P less than 0.05. Although a significant portal systemic shunt does exist in this 21-day model of obstructive jaundice, it does not appear to be the only mechanism underlying Kupffer cell dysfunction.

Muramyl dipeptide improves mononuclear phagocyte system function in obstructive jaundice

Previous studies have demonstrated depression of the mononuclear phagocyte system (MPS) of which the liver comprises 80-85% in animals subjected to 21 days of obstructive jaundice. This study examined the ability of a macrophage stimulant, muramyl dipeptide (MDP), to reverse MPS dysfunction in an obstructive jaundice rat model. Sixty-two male Sprague-Dawley rats underwent sham (n = 29) laparotomy or common duct ligation (CDL) (n = 33) and were studied after 21 days. Animals were injected with 1-3.5 X 10(6) Escherichia coli via a lateral tail vein, and colony-forming units (CFU) of the liver, lung, and spleen were determined at two time intervals: 30 min postinjection to determine the phagocytic activity of MPS (sham, n = 16; CDL, n = 20) and 24 hr postinjection to determine cytotoxic activity of MPS (sham, n = 13; CDL, n = 13). MDP (3 micrograms/g) was administered subcutaneously 24 hr prior to E. coli injection in 6 sham and 10 CDL rats studied at the 30-min time interval and 7 sham and 7 CDL rats studied at the 24-hr time interval. Pretreatment with MDP appeared to reverse the impairment of phagocytic activity in the liver of CDL rats returning it to the level of sham animals (P less than 0.05). However, pretreatment with MDP did not enhance the cytotoxic activity of the MPS as evidenced by higher CFU of E. coli in the liver, lung, and spleen of CDL animals pretreated with MDP as compared to CDL animals that did not receive MDP pretreatment. This increase was only significant in the spleen.(ABSTRACT TRUNCATED AT 250 WORDS)