Endotoxaemia and renal failure in cirrhosis and obstructive jaundice

Pathophysiology of Hepatorenal Syndrome

Hepatorenal syndrome type 1 (HRS-1) is a unique form of acute kidney injury that affects individuals with decompensated cirrhosis with ascites. The primary mechanism leading to reduction of kidney function in HRS-1 is hemodynamic in nature. Cumulative evidence points to a cascade of events that led to a profound reduction in kidney perfusion. A state of increased intrahepatic vascular resistance characteristic of advanced cirrhosis and portal hypertension is accompanied by maladaptive peripheral arterial vasodilation and reduction in systemic vascular resistance and mean arterial pressure. As a result of a fall in effective arterial blood volume, there is a compensatory activation of the sympathetic nervous system and the renin-angiotensin system, local renal vasoconstriction, loss of renal autoregulation, decrease in renal blood flow, and ultimately a fall in glomerular filtration rate. Systemic release of nitric oxide stimulated by the fibrotic liver, bacterial translocation, and inflammation constitute key components of the pathogenesis. While angiotensin II and noradrenaline remain the critical mediators of renal arterial and arteriolar vasoconstriction, other novel molecules have been recently implicated. Although the above-described mechanistic pathway remains the backbone of the pathogenesis of HRS-1, other noxious elements may be present in advanced cirrhosis and likely contribute to the renal impairment. Direct liver-kidney crosstalk via the hepatorenal sympathetic reflex can further reduce renal blood flow independently of the systemic derangements. Tense ascites may lead to intraabdominal hypertension and abdominal compartment syndrome. Cardio-hemodynamic processes have also been increasingly recognized. Porto-pulmonary hypertension, cirrhotic cardiomyopathy, and abdominal compartment syndrome may lead to renal congestion and complicate the course of HRS-1. In addition, a degree of ischemic or toxic (cholemic) tubular injury may overlap with the underlying circulatory dysfunction and further exacerbate the course of acute kidney injury. Improving our understanding of the pathogenesis of HRS-1 may lead to improvements in therapeutic options for this seriously ill population.

Reappraising the spectrum of AKI and hepatorenal syndrome in patients with cirrhosis

The occurrence of acute kidney injury (AKI) in patients with end-stage liver disease constitutes one of the most challenging clinical scenarios in in-hospital and critical care medicine. Hepatorenal syndrome type 1 (HRS-1), which is a specific type of AKI that occurs in the context of advanced cirrhosis and portal hypertension, is associated with particularly high mortality. The pathogenesis of HRS-1 is largely viewed as a functional derangement that ultimately affects renal vasculature tone. However, new insights suggest that non-haemodynamic tubulo-toxic factors, such as endotoxins and bile acids, might mediate parenchymal renal injury in patients with cirrhosis, suggesting that concurrent mechanisms, including those traditionally associated with HRS-1 and non-traditional factors, might contribute to the development of AKI in patients with cirrhosis. Moreover, histological evidence of morphological abnormalities in the kidneys of patients with cirrhosis and renal dysfunction has prompted the functional nature of HRS-1 to be re-examined. From a clinical perspective, a diagnosis of HRS-1 guides utilization of vasoconstrictive therapy and decisions regarding renal replacement therapy. Patients with cirrhosis are at risk of AKI owing to a wide range of factors. However, the tools currently available to ascertain the diagnosis of HRS-1 and guide therapy are suboptimal. Short of liver transplantation, goal-directed haemodynamically targeted pharmacotherapy remains the cornerstone of treatment for this condition; improved understanding of the underlying pathogenic mechanisms might lead to better clinical outcomes. Here, we examine our current understanding of the pathophysiology of HRS-1 and existing challenges in its diagnosis and treatment.

Acute Renal Failure in Hepatitis A

A 21-year-old man developed acute renal failure early in the course of hepatitis A infection and recovered after 17 days. There was no evidence of pre-renal azotemia, the hepato-renal syndrome, ischemic acute tubular necrosis, rhabdomyolysis, or thrombotic microangiopathy. There was, however, transient proteinuria and hypocomplementemia. It would appear that the renal failure resulted from viral-induced injury, either direct or mediated by immune complexes.

Gut Microbiome-based Therapeutics in Liver Cirrhosis: Basic Consideration for the Next Step

Infections account for significant morbidity and mortality in liver cirrhosis and most are related to the gut microbiome. Fecal dysbiosis, characterized by an overgrowth of potentially pathogenic bacteria and a decrease in autochthonous non-pathogenic bacteria, becomes prominent with the progression of liver cirrhosis. In cirrhotic patients, disruption of the intestinal barrier causes intestinal hyperpermeability (i.e. leaky gut), which is closely related to gut dysmotility, dysbiosis and small intestinal bacterial overgrowth and may induce pathological bacterial translocation. Although the involved microbial taxa are somewhat different between the cirrhotic patients from the East and the West, the common manifestation of a shortage of bacteria that contribute to the production of short-chain fatty acids and secondary bile acids may facilitate intestinal inflammation, leaky gut and gut dysbiosis. Translocated endotoxin and bacterial DNA are capable of provoking potent inflammation and affecting the metabolic and hemodynamic systems, which may ultimately enhance the progression of liver cirrhosis and its various complications, such as hepatic encephalopathy (HE), variceal bleeding, infection and renal disturbances. Among studies on the microbiome-based therapeutics, findings of probiotic effects on HE have been contradictory in spite of several supportive results. However, the effects of synbiotics and prebiotics are substantially documented. The background of their effectiveness should be evaluated again in relation to the cirrhosis-related changes in gut microbiome and their metabolic effects. Strict indications for the antibiotic rifaximin remain unestablished, although its effect is promising, improving HE and other complications with little influence on microbial populations. The final goal of microbiome-based therapeutics is to adjust the gut-liver axis to the maximal benefit of cirrhotic patients, with the aid of evolving metagenomic and metabolomic analyses.

Altered circadian hemodynamic and renal function in cirrhosis

Background

Given that alterations in systemic hemodynamics have a profound influence on renal function in patients with cirrhosis, it is surprising that circadian variations in blood pressure (BP) and renal electrolyte excretion have scarcely been studied. Our aims were to define the relationship of 24-h ambulatory BP changes with renal tubular function and to determine the influence of endotoxemia on BP and urinary parameters.

Methods

Forty healthy controls served as a comparator to 20 cirrhotic patients. They underwent 24-h ambulatory BP monitoring and 24-h urine collection.

Results

Subjects with cirrhosis demonstrated significant diurnal variations in urinary excretion of sodium (57.7 µmol/min day versus 87 µmol/min night) and creatinine (826 µg/min day versus 1202 µg/min night). Increasing severity of cirrhosis was associated with a progressive reduction in ambulatory awake systolic (P-trend = 0.015), diastolic (P-trend < 0.001) and mean BP (P-trend < 0.001). In patients with cirrhosis, the magnitude of change in BP from awake to sleep state was blunted for systolic BP (5% reduction, P = 0.039) and pulse rate (2% reduction, P < 0.001). The amplitude of variation in pulse rate was blunted with increasing severity of cirrhosis (controls 6.5, Child-Pugh Class A 5.3, Child B 3.4, Child C 1.2, P = 0.03) and the acrophase was right-shifted with increasing severity of cirrhosis. Compared with sleep state, during the awake state, endotoxin was associated with less sodium excretion and a lower systolic BP. Compared with the awake state, endotoxin was associated with a higher sleeping pulse rate (P < 0.001).

Conclusions

Patients with cirrhosis have altered diurnal profiles in renal tubular function and blood pressure that appear to be related to endotoxemia. Determining whether endotoxemia is causally related to these perturbations will require interventional studies.

Systematic review: bile acids and intestinal inflammation-luminal aggressors or regulators of mucosal defence?

BACKGROUND

Inflammatory bowel diseases (IBD), comprising Crohn's disease and ulcerative colitis (UC), are chronic conditions attributed to an aberrant immune response to luminal triggers. Recently, published work suggests a pathogenic role for bile acids in this context.

AIM

To perform a systematic review of studies investigating the role of bile acids in intestinal inflammation and present potentially relevant clinical implications.

METHODS

Pubmed search for English language articles published up to May 2015. Terms used were: 'bile', 'bile acid', 'barrier', 'small bowel injury', 'Crohn's' and 'colitis'.

RESULTS

Experimental studies support a variable role for bile acids in intestinal barrier homoeostasis. This may be attributed to different physicochemical properties, variable effects on epithelia and immune cells via bile acids-specific receptors, or through a cross-talk with the gut microbiome. A reduction in the bile acids pool, with lower concentrations of secondary forms, has been recognised for some time in Crohn's disease and associated to ileal dysfunction and bile acids malabsorption. Recent work suggests that these changes, including an increase in sulphated forms, are related to inflammatory activity in both Crohn's disease and UC. The detrimental effects of 'western diet' elements such as emulsifiers and fat, which have been implicated in the development of the current IBD and obesity epidemics, may also be bile acid-mediated.

CONCLUSIONS

Although there are only a few observational clinical studies to support an interaction, in vivo human and animal studies support an association between bile acids metabolism, the gut microbiome and intestinal inflammation. This may well prove to have significant diagnostic and therapeutic implications.

Quantitative lipopolysaccharide analysis using HPLC/MS/MS and its combination with the limulus amebocyte lysate assay

Quantitation of plasma lipopolysaccharides (LPSs) might be used to document Gram-negative bacterial infection. In the present work, LPS-derived 3-hydroxymyristate was extracted from plasma samples with an organic solvent, separated by reversed phase HPLC, and quantitated by MS/MS. This mass assay was combined with the limulus amebocyte lysate (LAL) bioassay to monitor neutralization of LPS activity in biological samples. The described HPLC/MS/MS method is a reliable, practical, accurate, and sensitive tool to quantitate LPS. The combination of the LAL and HPLC/MS/MS analyses provided new evidence for the intrinsic capacity of plasma lipoproteins and phospholipid transfer protein to neutralize the activity of LPS. In a subset of patients with systemic inflammatory response syndrome, with documented infection but with a negative plasma LAL test, significant amounts of LPS were measured by the HPLC/MS/MS method. Patients with the highest plasma LPS concentration were more severely ill. HPLC/MS/MS is a relevant method to quantitate endotoxin in a sample, to assess the efficacy of LPS neutralization, and to evaluate the proinflammatory potential of LPS in vivo.

Gut-liver axis in liver cirrhosis: How to manage leaky gut and endotoxemia

A “leaky gut” may be the cutting edge for the passage of toxins, antigens or bacteria into the body, and may play a pathogenic role in advanced liver cirrhosis and its complications. Plasma endotoxin levels have been admitted as a surrogate marker of bacterial translocation and close relations of endotoxemia to hyperdynamic circulation, portal hypertension, renal, cardiac, pulmonary and coagulation disturbances have been reported. Bacterial overgrowth, increased intestinal permeability, failure to inactivate endotoxin, activated innate immunity are all likely to play a role in the pathological states of bacterial translocation. Therapeutic approach by management of the gut-liver axis by antibiotics, probiotics, synbiotics, prebiotics and their combinations may improve the clinical course of cirrhotic patients. Special concern should be paid on anti-endotoxin treatment. Adequate management of the gut-liver axis may be effective for prevention of liver cirrhosis itself by inhibiting the progression of fibrosis.

Bile acids trigger cholemic nephropathy in common bile-duct-ligated mice

Tubular epithelial injury represents an underestimated but important cause of renal dysfunction in patients with cholestasis and advanced liver disease, but the underlying mechanisms are unclear. To address the hypothesis that accumulation and excessive alternative urinary elimination of potentially toxic bile acids (BAs) may contribute to kidney injury in cholestasis, we established a mouse model for detailed in vivo time course as well as treatment studies. Three-day common bile duct ligation (CBDL) induced renal tubular epithelial injury predominantly at the level of aquaporin 2-positive collecting ducts with tubular epithelial and basement membrane defects. This was followed by progressive interstitial nephritis and tubulointerstitial renal fibrosis in 3-, 6-, and 8-week CBDL mice. Farnesoid X receptor knockout mice (with a hydrophilic BA pool) were completely protected from CBDL-induced renal fibrosis. Prefeeding of hydrophilic norursodeoxycholic acid inhibited renal tubular epithelial injury in CBDL mice. In addition, we provide evidence for renal tubular injury in cholestatic patients with cholemic nephropathy.

CONCLUSION

We characterized a novel in vivo model for cholemic nephropathy, which offers new perspectives to study the complex pathophysiology of this condition. Our findings suggest that urinary-excreted toxic BAs represent a pivotal trigger for renal tubular epithelial injury leading to cholemic nephropathy in CBDL mice.

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.

Diseases of the gallbladder and biliary tree

Most disorders of the biliary system are associated with increased activity of parenchymal transaminases (alanine aminotransferase, aspartate aminotransferase) and cholestatic enzymes (alkaline phosphatase and gamma glutamyl transferase) with or without hyperbilirubinemia or jaundice. While parenchymal liver disease is most common in the dog, inflammatory disorders involving the small- and medium-sized bile ducts and zone 1 (periportal) hepatocytes predominate in the cat. Historically, the incidence of disorders restricted to the gallbladder is low in both species; however, with routine diagnostic use of abdominal ultrasonography, the incidence of gallbladder mucoceles and cholelithiasis has increased. Extrahepatic bile duct obstruction is a well-recognized syndrome because of its association with pancreatitis and obvious jaundice. Less common disorders of the biliary system include a cadre of diverse conditions, including necroinflammatory processes, cholelithiasis, malformations, neoplasia, and an emerging syndrome of gallblader dysmotility.

Renal effects of gentamicin in chronic bile duct ligated rats

Patients with advanced cirrhosis and rats with short-term bile duct ligation (BDL) are prone to develop nephrotoxicity from aminoglycosides. In this study, we characterized the renal response to gentamicin in rats with chronic BDL. BDL and sham-operated (SO) rats were given gentamicin (20 and 40 mg/kg/d) for 7 consecutive days, starting on the 18th postoperative day. Administration of gentamicin to SO group caused a decrease in cortical and medullary prostaglandin E(2)(PGE(2)) generation. However, mild reduction in creatinine clearance and an increase in fractional excretion of sodium occurred only in the BDL rats given the high gentamicin dose. This was accompanied by a reduction in cortical and medullary PGE(2) generation and a reduction in plasma nitric oxide production. In conclusion, gentamicin administration to rats with chronic BDL causes impairment of renal function. This happens only after the occurrence of simultaneous multiple insults to the renal protective mechanisms.

Variables Associated with Outcome in Dogs Undergoing Extrahepatic Biliary Surgery: 60 Cases (1988-2002)

OBJECTIVE

To report clinical findings and define clinical variables associated with outcome in dogs undergoing extrahepatic biliary surgery.

STUDY DESIGN

Retrospective study.

ANIMALS

Sixty dogs that had extrahepatic biliary tract surgery.

RESULTS

Primary diagnoses included necrotizing cholecystitis (36 dogs, 60%), pancreatitis (12 dogs, 20%), neoplasia (5 dogs, 8%), trauma (4 dogs, 7%), and gallbladder rupture from cholelithiasis without necrotizing cholecystitis (3 dogs, 5%). Bile peritonitis occurred in 19 (53%) dogs with necrotizing cholecystitis, 4 dogs with trauma, and 3 dogs with cholelithiasis without evidence of necrotizing cholecystitis. Cholecystectomy (37 dogs, 62%) and cholecystoduodenostomy (14 dogs, 23%) were the 2 most commonly performed procedures. Median hospitalization for survivors was 5 days (range, 1-15 days). There were 43 surviving dogs (72%) and 17 nonsurvivors (28%, 4 died, 13 euthanatized). Presence of septic bile peritonitis (P=.038), elevation in serum creatinine concentration (P=.003), prolonged partial thromboplastin times (PTTs; P=.003), and lower postoperative mean arterial pressures (P=.0001) were significantly associated with mortality.

CONCLUSIONS

Extrahepatic biliary surgery is associated with high mortality and a relatively long hospitalization time for survivors. Cholecystectomy and cholecystoduodenostomy were the most common surgical procedures to treat the 4 major biliary problems (necrotizing cholecystitis, pancreatitis, neoplasia, and trauma) observed in this cohort of dogs. The relatively high mortality rate likely reflects the underlying diseases and their effects on the animal (septic bile peritonitis, higher serum creatinine, prolonged PTT, and lower postoperative mean arterial pressure) rather than complications of surgery.

CLINICAL RELEVANCE

Septic bile peritonitis, preoperative elevated creatinine concentration, and immediate postoperative hypotension in dogs undergoing extrahepatic biliary tract surgery are associated with a poor clinical outcome. Adequate supportive care and monitoring in the perioperative period is critical to improve survival of dogs with extrahepatic biliary disease.

The effect of pentoxifylline on the healing of intestinal anastomosis in rats with experimental obstructive jaundice

The aims of this study were (1) to investigate the effect of experimental obstructive jaundice on the healing of intestinal anastomosis, and (2) to investigate the effect of pentoxifylline on the healing of intestinal anastomosis in rats with obstructive jaundice. Obstructive jaundice was induced in rats by the ligation and division of the common bile duct. Four days after this operation, either pentoxifylline or isotonic saline solution was administered intraperitoneally to these jaundiced rats and controls, and then intestinal anastomosis was performed. The concentrations of serum tumor necrosis factor alpha (TNF-alpha) and serum triglyceride of jaundiced and nonjaundiced rats were measured, and the quality of healing was evaluated by measuring the bursting pressure and hydroxyproline content of the anastomoses on the fifth and tenth days of anastomotic healing. Obstructive jaundice resulted in an impaired wound healing of the intestinal anastomosis in the rats. The administration of pentoxifylline to the jaundiced rats resulted in better anastomotic wound healing. The beneficial effects of pentoxifylline on anastomotic healing in rats with obstructive jaundice was attributed to its inhibitor effect on the endotoxin-induced TNF-alpha release from macrophages and monocytes, and the stabilizing effect on the neutrophils.

Role of endotoxin and nitric oxide in the pathogenesis of renal failure in obstructive jaundice

BACKGROUND

There is an increased incidence of postoperative renal failure in patients with obstructive jaundice. The purpose of this study was to investigate the role of endotoxaemia and nitric oxide in this association.

METHODS

In bile duct-ligated, sham-operated and control rats, plasma total bilirubin levels, creatinine clearance and plasma endotoxin were determined. Endothelium-dependent vasodilatation to acetylcholine, and endothelium-independent vasodilatation to nitroglycerine and forskolin were evaluated in isolated perfused rat kidney.

RESULTS

Twenty-one of 27 bile-duct ligated rats had endotoxaemia. Plasma bilirubin levels were higher and creatinine clearance was significantly reduced in the bile duct-ligated endotoxin-positive group compared with values in the other groups. Furthermore, in the isolated perfused rat kidney from rats with endotoxaemia, basal perfusion pressure and renal vascular relaxation to acetylcholine and nitroglycerine which is mediated by guanosine cyclic 3',5'-cyclic monophosphate (cGMP) were significantly reduced, but relaxation to forskolin mediated by adenosine cyclic 3',5'-cyclic monophosphate did not change.

CONCLUSION

Endotoxaemia in obstructive jaundice may induce overproduction of nitric oxide that may lead to impairment of cGMP-associated vasodilatation and disrupt autoregulation of the renal vascular bed. This may contribute to renal failure in obstructive jaundice.

Translocação bacteriana para o rim na icterícia obstrutiva experimental

Estudo com o objetivo de verificar a possibilidade de ocorrência de translocação bacteriana para os rins de ratos, após ligadura de colédoco. Foram utilizados 29 ratos Wistar com peso médio de 171 ± 12,6g. Os animais foram divididos aleatoriamente em grupo I (n=14) e grupo II (n=15). Com técnica asséptica, nos ratos no grupo I foi feita ligadura de colédoco com fio de seda nº 3 zeros e no grupo II foi simulada a ligadura com a simples manipulação do colédoco com pinça de Adson ("sham operation"). No 7º dia pós-operatório os animais foram sacrificados e ressecados os rins para exame histopatológico (coloração H.E.) e microbiológico (meios agar sangue e agar MacConkey). Houve crescimento bacteriano de Klebsiela sp em 28,5% dos casos no grupo I e foram observadas alterações histopatológicas significativas no mesmo grupo. As diferenças foram estatisticamente significantes quando foram comparados os 2 grupos (p<0,05). Concluímos que a icterícia obstrutiva em ratos provoca translocação bacteriana para os rins e alterações histopatológicas associadas.

Gut endotoxin restriction prevents catabolic changes in glutamine metabolism after surgery in the bile duct-ligated rat

OBJECTIVE

The objective of this study was to investigate the role of gut-derived endotoxemia in postoperative glutamine (GLN) metabolism of bile duct-ligated rats.

SUMMARY BACKGROUND DATA

Postoperative complications in patients with obstructive jaundice are associated with gut-derived endotoxemia. In experimental endotoxemia, catabolic changes in GLN metabolism have been reported. Glutamine balance is considered important in preventing postsurgical complications.

METHODS

Male Wistar rats were treated orally with the endotoxin binder cholestyramine (n = 24, 150 mg/day) or saline (n = 24). On day 7, groups received a SHAM operation or a bile duct ligation (BDL). On day 21, all rats were subjected to a laparotomy followed 24 hours later by blood flow measurements and blood sampling. Glutamine organ handling was determined for the gut, liver, and one hindlimb. Intracellular GLN muscle concentrations were determined.

RESULTS

Compared to the SHAM groups, BDL rats showed lower gut uptake of GLN (28%, p < 0.05); a reversal of liver GLN release to an uptake (p < 0.05); higher GLN release from the hindlimb (p < 0.05); and lower intracellular muscle GLN concentration (32%, p < 0.05). Cholestyramine treatment in BDL rats maintained GLN organ handling and muscle GLN concentrations at SHAM levels.

CONCLUSIONS

Disturbances in postoperative GLN metabolism in BDL rats can be prevented by gut endotoxin restriction. Gut-derived endotoxemia after surgery in obstructive jaundice dictates GLN metabolism.

Perioperative anti-endotoxin strategies

Lipopolysaccharides from the outer membrane of Gram-negative bacteria are potent stimuli for the production of numerous cytokines by the immune cells. The systemic inflammatory response to these gut-derived endotoxins is therefore dependent on the responsiveness of the immune system. This paper presents results on anti-endotoxin strategies and the responsiveness to endotoxin in animal models of liver failure. Following partial hepatectomy in the normal rat, anti-endotoxin treatment using the enteral endotoxin binder cholestyramine and the bactericidal permeability-increasing protein showed beneficial effects in terms of reducing the exaggerated metabolic and inflammatory responses. Similar beneficial effects of gut endotoxin restriction were found in bile duct ligated rats subjected to a laparotomy. The beneficial effects of anti-endotoxin strategies in these models were explained by completely different mechanisms. In partial hepatectomized rats the effects were explained by the direct inhibition of the stimulatory action of endotoxin on immune cells preventing an exaggerated inflammatory response. In contrast, in postoperative BDL rats the effects of anti-endotoxin therapy were explained by the restoration of endotoxin sensitivity of the immune cells resulting in an inflammatory response necessary for an adequate reaction to surgery. These different mechanism will be discussed in the light of the phenomenon of endotoxin tolerance.

Lactulose and renal failure

The introduction of lactulose as a new therapeutic agent for treatment of hepatic encephalopathy was a major breakthrough in this field. It was hypothesized that lactulose might prevent postoperative renal impairment after biliary surgery in patients with obstructive jaundice. The presumable mechanism purported was the diminished endotoxinemia by lactulose. Unfortunately, such a reno-protective effect has not been shown conclusively until now in clinical studies. In chronic renal failure lactulose is known to promote fecal excretion of water, sodium, potassium, amonium, urea, creatinine and protons. Thus, lactulose could be useful for the treatment of chronic renal failure. However, compliance to the therapy represents a major problem.

Bacterial translocation and gut microflora in obstructive jaundice

Bacterial translocation from the gut is implicated in the pathophysiology of complications associated with obstructive jaundice. Absence of intraluminal bile salts and their antiendotoxic effects may result in overgrowth of bacteria, promoting bacterial translocation. The large bowel is the largest source of gram negative bacteria but the small bowel is more permeable. This study investigated the effect of obstructive jaundice on bacterial translocation and on the indigenous luminal microflora at 3 sites in the gastrointestinal tract. Significant bacterial translocation was demonstrated following 7 d of bile duct ligation compared with control or sham operated groups. A qualitative disturbance of the caecal indigenous microflora was demonstrated in jaundiced rats. There was no 'site-to-site' variation in the indigenous microflora at the 3 intestinal sites studied. We conclude that experimental obstructive jaundice for 1 wk promotes bacterial translocation without significant quantitative disturbance of the intestinal microflora in the small intestinal or caecum.

Acute renal failure complicating nonfulminant hepatitis A

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Role of the gut in the pathophysiology of extrahepatic biliary obstruction

BACKGROUND

Gram negative septic events are the commonest source of morbidity and mortality as a result of surgery in jaundiced patients. The large intestine provides the major source of Gram negative bacteria in mammals and is implicated in the pathogenesis of systemic endotoxaemia in obstructive jaundice. Bile salts have an important part in maintaining indigenous microecological homeostasis through their emulsifying properties.

AIMS

The aim was to investigate the effects of biliary obstruction and isolated external biliary diversion on gastro-intestinal structure and caecal bacterial flora in relation to bacterial translocation.

METHOD

Six groups of adult male Wistar rats were studied (no operation, sham operated, and bile duct ligated (BDL) for one and three weeks and a choledocho-vesical fistula (CDVF) for one week). At the end of the study period plasma was assayed for evidence of endotoxaemia and the animals were tested for bacterial translocation to the mesenteric lymph node complex (MLNC), liver, lungs, and spleen. Quantitative and qualitative bacteriological studies were performed on the caecal contents and segments of colon and terminal ileum were washed and prepared for histological assessment.

RESULTS

Bacterial translocation was significantly increased in the BDL1 (68.8%) and BDL3 (60%) groups compared with the sham1 (6.3%), sham3 (9.1%), No operation (0%), and CDVF1 (16.7%) groups. Although translocation was more pronounced in the BDL1 group, this was almost exclusively to the MLNC compared with the more widespread translocation to other organs in the BDL3 group. The BDL3 group was the only group with significantly raised concentrations of endotoxin and anticore glycolipid. The caecal Gram negative aerobic counts were significantly increased in the BDL1 and CDVF1 groups compared with all other groups. There was evidence of structural abnormalities in the terminal ileum of rats jaundiced for three weeks, but not in the other groups.

CONCLUSIONS

Biliary obstruction for one and three weeks promotes bacterial translocation although the mechanisms may be different. Absence of intralumenal bile results in a significant but self limiting increase in the Gram negative aerobic population, which may account for translocation in the early stages of biliary obstruction. As the duration of biliary obstruction increases systemic endotoxaemia is a consistent feature which, combined with factors such as immunological depression and physical disruption of gut barrier function, may promote bacterial translocation perpetuating systemic sepsis.

Obstructive jaundice causes reduced expression of polymorphonuclear leucocyte adhesion molecules and a depressed response to bacterial wall products in vitro

BACKGROUND

Obstructive jaundice is associated with an increased incidence of infection and endotoxaemia, which may result from impaired host immunity. Neutrophil adhesion to vascular endothelium is a key part of the inflammatory response.

AIMS

To investigate neutrophil adhesion molecule expression and activation in obstructive jaundice.

PATIENTS

Nine adult patients with obstructive jaundice and 11 control subjects.

METHODS

The expression of the neutrophil adhesion receptors L-selectin, CD11a, CD11b, CD11c, and CD15 was determined using flow cytometry. CD11b expression in response to stimulation with fMLP and endotoxin was measured.

RESULTS

The basal expression of L-selectin, CD11a, and CD15 was significantly decreased in jaundiced patients (p < 0.05) and the expression of CD11b in response to stimulation with fMLP and endotoxin was significantly impaired in the jaundiced group. Endotoxin stimulation without plasma did not reverse the impaired response showing that it is not caused by endotoxin inactivation by plasma proteins.

CONCLUSIONS

Neutrophils from patients with obstructive jaundice show decreased adhesion receptor expression and an impaired response to stimulation with bacterial products. This cellular dysfunction may be responsible for the high incidence of septic complications in these patients.

The hepatorenal syndrome

Hepatorenal syndrome may occur in any form of severe liver disease. It appears less common in children than adults, but still carries a poor prognosis. There are several factors involved in its aetiology, including a decreased renal perfusion pressure, activation of the renal sympathetic nervous system and increased synthesis of several vasoactive mediators, which may modulate glomerular filtration by acting as both renal vasoconstrictors and dynamic regulators of the glomerular capillary ultrafiltration coefficient, through their action on mesangial cells. This review will discuss the pathophysiology of the hepatorenal syndrome and some of the principles of management of patients with renal failure and severe liver disease. The role of renal support and liver transplantation will also be covered.

Renal dysfunction in obstructive jaundice

The association between renal dysfunction and obstructive jaundice is well established. Despite a substantial number of clinical reviews and prospective studies, the exact incidence and extent of the problem has not been determined accurately. Various pathogenic mechanisms and therapeutic strategies have been proposed but renal dysfunction remains a persistent problem in hepatobiliary practice. The intention of this review is to determine the current extent of the problem, outline the proposed pathophysiological mechanisms and assess the current therapeutic options.

Aminoglycoside-associated nephrotoxicity in extrahepatic obstructive jaundice

Experimental data demonstrate that biliary obstruction increases renal sensitivity to gentamicin. In the present study the incidence of and risk factors for aminoglycoside nephrotoxicity were prospectively studied in patients with extrahepatic obstructive jaundice. Two hundred and thirty-seven hospitalized adult patients were classified into three groups. Group I consisted of 84 patients with extrahepatic obstructive jaundice, who received aminoglycoside (gentamicin or tobramycin). Group II consisted of 81 patients with extrahepatic obstructive jaundice, who received either antibiotics other than aminoglycoside or no antimicrobial therapy. Group III consisted of 72 noncholestatic patients receiving aminoglycosides for different disorders. Nephrotoxicity developed in 27 patients (32%) in group I vs 9 patients (11%) in group II and 4 patients (5.6%) in group III (p < 0.00001). In group I, a comparison of patients with and without nephrotoxicity revealed significantly higher values in the former for mean serum bilirubin concentration, initial steady-state trough aminoglycoside concentration and estimated half-life. Stepwise multivariate analysis with nephrotoxicity status as the dependent variable determined that the most significant variable for predicting nephrotoxicity was serum total bilirubin level. In extrahepatic cholestasis a high serum bilirubin level is a distinct factor predisposing to aminoglycoside nephrotoxicity.

Effects of ursodeoxycholic acid on hemodynamic and renal function abnormalities induced by obstructive jaundice in rats

The mechanism of renal function abnormalities in experimental biliary cirrhosis can be partially explained by the absence of gastrointestinal bile flow, which predisposes to translocation of intestinal endotoxin, a potent renal vasoconstrictor. Since bile acids prevent the absorption of intestinal endotoxins, we aimed to evaluate the effects of ursodeoxycholic acid (UDCA) administration on renal function and hemodynamic abnormalities induced by 1 week of obstructive jaundice in rats.

METHODS

Fifty-two rats were used; 30 had ligation of the common bile duct, 22 were sham operated. Bile duct ligated rats were randomly and blindly assigned to receive UDCA (25 mg/kg/day, n = 14) or placebo (n = 16) during 1 week. Sham rats received no treatment. Portal pressure (PP) as well as creatinine clearance (CrCl), urinary sodium (US), and plasma renin activity (PRA) were evaluated. Results are mean +/- SEM, with a significant value of p < 0.05.

RESULTS

Portal pressure (10.4 +/- 1.1 vs. 12.1 +/- 0.8 mm Hg) was significantly lower in UDCA than in placebo-treated rats. ALT serum levels were also significantly lower in bile duct ligated rats receiving UDCA (77.3 +/- 28 IU/L) than in placebo-treated rats (162 +/- 65 IU/L). US (1.1 +/- 0.5 vs. 2.1 +/- 0.3 mEq/24 h) was significantly lower and PRA (6.0 +/- 2.6 vs. 1.9 +/- 1.0 ng Ang 1/mL/h) higher in bile duct ligated than in sham-operated rats. No differences were found between UDCA or placebo-treated bile duct ligated rats. CrCl was similar between sham (0.39 +/- 0.12 mL/min/100 g BW) and UDCA (0.32 +/- 0.16) but significantly lower in placebo-treated (0.28 +/- 0.07) than sham-operated rats (p < 0.05).

CONCLUSION

UDCA administration had very mild effects on renal function abnormalities induced by experimental obstructive jaundice in rats. However, portal hypertension and biochemical abnormalities were partially improved.

Isoprostanes. Novel markers of endogenous lipid peroxidation and potential mediators of oxidant injury

It was recently discovered that a series of structurally unique prostaglandin F2-like compounds (F2-isoprostanes) capable of exerting potent biological activity are produced in vivo in humans by a noncyclooxygenase mechanism involving free radical catalyzed peroxidation of arachidonic acid. Considerable evidence has been obtained suggesting that quantification of F2-isoprostanes represents an important advance in our ability to assess oxidant status in vivo in humans. This has allowed us to implicate oxidant stress in the pathogenesis of human disease-for example, the hepatorenal syndrome. In addition to the F2-isoprostanes, we recently discovered that E-ring and D-ring isoprostanes are also produced in abundance in vivo by rearrangement of the isoprostane endoperoxide intermediates. We have also been able to demonstrate that one of the E2-isoprostanes, 8-epi-PGE2, is a potent renal vasoconstrictor in the rat. Insights into factors that may influence the formation of E2/D2-isoprostanes relative to F2-isoprostanes should be important in advancing our understanding of the biological consequences of the formation of isoprostanes in vivo.

Dynamic aspects of glutathione metabolism in obstructive jaundice

The dynamic aspects of glutathione metabolism during obstructive jaundice were analyzed in rats. Plasma bilirubin levels increased after ligation of the bile duct, with a concomitant increase in hepatorenal glutathione levels. When the bile duct was recanalized, plasma bilirubin levels rapidly decreased, with a concomitant decrease in hepatorenal glutathione levels. The half-life of hepatic glutathione turnover increased markedly after bile duct obstruction, returning to normal after recanalization of the bile duct. Intravenous administration of a loading dose of bilirubin inhibited the biliary secretion of glutathione in a dose-dependent manner. On the other hand, renal glutathione efflux increased markedly after bile duct obstruction. These observations suggest that glutathione status is significantly affected in obstructive jaundice, predominantly due to the inhibition of hepatic secretion by increased bilirubin.

Clinical significance of translocation

The gastrointestinal tract, besides being the organ responsible for nutrient absorption, is also a metabolic and immunological system, functioning as an effective barrier against endotoxin and bacteria in the intestinal lumen. The passage of viable bacteria from the gastrointestinal tract through the epithelial mucosa is called bacterial translocation. Equally important may be the passage of bacterial endotoxin through the mucosal barrier. This article reviews the evidence that translocation of both endotoxin and bacteria is of clinical significance. It summarises recent published works indicating that translocation of endotoxin in minute amounts is a physiological important phenomenon to boost the reticuloendothelial system (RES), especially the Kupffer cells, in the liver. Breakdown of both the mucosal barrier and the RES capacity results in systemic endotoxaemia. Systemic endotoxaemia results in organ dysfunction, impairs the mucosal barrier, the clotting system, the immune system, and depresses Kupffer cell function. If natural defence mechanisms such as lipopolysaccharide binding protein, high density lipoprotein, in combination with the RES, do not respond properly, dysfunction of the gut barrier results in bacterial translocation. Extensive work on bacterial translocation has been performed in animal models and occurs notably in haemorrhagic shock, thermal injury, protein malnutrition, endotoxaemia, trauma, and intestinal obstruction. It is difficult to extrapolate these results to humans and its clinical significance is not clear. The available data show that the resultant infection remains important in the development of sepsis, especially in the critically ill patient. Uncontrolled infection is, however, neither necessary nor sufficient to account for the development of multiple organ failure. A more plausible sequelae is that bacterial translocation is a later phenomenon of multiple organ failure, and not its initiator. It is hypothesized that multiple organ failure is more probably triggered by the combination of tissue damage and systemic endotoxaemia. Endotoxaemia, as seen in trauma patients especially during the first 24 hours, in combination with tissue elicits a systemic inflammation, called Schwartzmann reaction. Interferon gamma, a T cell produced cytokine, is thought to play a pivotal part in the pathogenesis of this reaction. This reaction might occur only if the endotoxin induced cytokines like tumour necrosis factor and interleukin 1, act on target cells prepared by interferon gamma. After exposure to interferon gamma target cells become more sensitive to stimuli like endotoxin, thus boosting the inflammatory cycle. Clearly, following this line of reasoning, minor tissue damage or retroperitoneal haematoma combined with systemic endotoxaemia could elicit this reaction. The clinically observed failure of multiple organ systems might thus be explained by the interaction of tissue necrosis and high concentrations of endotoxin because of translocation. Future therapeutic strategies could therefore focus more on binding endotoxin in the gut before the triggering event, for example before major surgery. Such a strategy could be combined with the start of early enteral feeding, which has been shown in animal studies to have a beneficial effect on intestinal mucosal barrier function and in traumatized patients to reduce the incidence of septic complications.

Coley's toxins, tumor necrosis factor and cancer research: a historical perspective

As far back as the 1700s, it was recorded that certain infectious disease processes could exert a beneficial therapeutic effect upon malignancy. Most prominent among the numerous deliberate efforts made to take advantage of these observations was that of a pioneering New York surgeon, William B. Coley, active career 1891-1936. Using a bacterial vaccine to treat primarily inoperable sarcoma. Coley accomplished a cure rate of better than 10%. This review examines the history of these efforts and presents a discussion of their corresponding relevance to present day immunotherapy.

Increased serum nitrite and nitrate levels in patients with cirrhosis: relationship to endotoxemia

Nitric oxide derived from vascular endothelium is a potent vasodilator that plays a key role in the homeostasis of blood pressure. Because cirrhotic patients tend to have low arterial pressure, we measured in 51 patients and 10 control subjects serum nitrite and nitrate levels as an index of in vivo nitric oxide generation. We also measured plasma endotoxin, a substance frequently increased in cirrhotic patients and known to induce nitric oxide synthesis. Cirrhotic patients showed significant increases in serum nitrite/nitrate and plasma endotoxin compared with controls. Values were particularly increased in patients with decompensated cirrhosis, as manifested by ascites with or without functional kidney failure. High serum nitrite/nitrate levels were associated with high plasma renin activity, high aldosterone and antidiuretic hormone levels and low urinary excretion of sodium. In addition, serum nitrite/nitrate levels significantly correlated with endotoxemia. Oral administration of colistin to 15 cirrhotic patients reduced significantly plasma endotoxin levels (p < 0.01) and serum nitrite/nitrate levels (p < 0.05). Because endotoxin enhances the expression of inducible nitric oxide synthase, our results suggest that circulating endotoxin in cirrhosis is responsible for excessive synthesis and release of nitric oxide by the vasculature. These findings might explain the hemodynamic dysfunction seen in cirrhotic patients.

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.

Haemodynamic alterations and their morphological basis in biliary obstruction

The relationship between the haemodynamic alterations and morphological changes in the liver caused by biliary obstruction was investigated in rats after ligation of the common bile duct. In these rats, the portal vein pressure was markedly elevated, and the differences in blood pressure between the portal vein and the terminal portal venule and between the terminal portal venule and the terminal hepatic venule were greater than in the sham-operated rat. The livers showed narrowing of the most peripheral branches of the portal vein due to compression by proliferated bile ductules and sinusoidal stenosis due to enlarged liver cells, but there was no perceptible change in the hepatic vein branches. These data suggest that hepatic circulatory disturbance in biliary obstruction is caused by deformation of the peripheral portal vein branches and sinusoidal stenosis.

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.

The endocrinology and pathophysiology of alcoholic cirrhosis and functional renal failure--a review

The pathophysiology and characteristics of decompensated alcoholic cirrhosis and functional renal failure are reviewed. The review will be restricted to alcoholic cirrhosis, because most cases of functional renal failure in the United States occur in the setting of alcoholic cirrhosis, which is also the most common cause of ascites in North America and Europe. Moreover, hepatorenal syndrome may complicate other forms of liver disease besides alcoholic cirrhosis, but the pathogenesis in such circumstances may not be the same as in the cirrhotic state.

Complications in obstructive jaundice: role of endotoxins

Surgical treatment of patients with obstructive jaundice is associated with a high postoperative morbidity and mortality. A correlation was suggested between endotoxins and the observed complications. The mechanism by which endotoxins affect the negative outcome in operated jaundiced patients was, however, not clear, nor was the mechanism of clinically used preventive treatments. Several experiments were therefore performed in rats with biliary obstruction, to investigate whether and how endotoxins are active. The role of endotoxins was studied in a model in which endotoxins were absent. In germfree rats (free of bacteria and thus of endotoxin) the effect of biliary obstruction was studied and compared with biliary obstruction in conventional rats. To substantiate further the role of endotoxin, anti-endotoxin treatments (oral lactulose or internal drainage) were tested in rats with obstructive jaundice undergoing a severe surgical trauma. It is shown that endotoxins are responsible for complications (suppression of cellular immunity, kidney function, mortality) and that these complications can be prevented with an anti-endotoxin treatment. These results may have implications for preoperative treatment of jaundiced patients.

Liver dysfunction in critical illness

Abnormal liver function commonly accompanies critical illness. Ischaemic hepatitis occurs with shock and is characterised by elevated plasma aminotransferase concentrations. 'ICU jaundice' occurs later in critical illness, especially after trauma and sepsis. The major biochemical abnormality is conjugated hyperbilirubinaemia. The clinical setting suggests that hepatic ischaemia and hepatotoxic actions of inflammatory mediators are the major aetiological factors. Massive blood transfusion, effects of nutritional support and drug toxicity may contribute. Both the presence and degree of jaundice are associated with increased mortality in several nonhepatic diseases. It is proposed that Kupffer cell phagocytic depression associated with liver dysfunction permits systemic spread of endotoxin and inflammatory mediators and thus predisposes to multiple organ failure. Immunosuppression, metabolic abnormalities, impaired drug oxidation and myocardial depression may contribute to the poor prognosis. There is no specific treatment, but prompt resuscitation, definitive treatment of sepsis and meticulous supportive care will likely reduce the incidence and severity.

Endotoxin concentrations measured by a chromogenic assay in portal and peripheral venous blood in ten dogs with portosystemic shunts

A chromogenic Limulus amebocyte lysate assay was used to measure portal and peripheral venous endotoxin concentrations in ten medically managed dogs undergoing surgery for correction of a single extrahepatic portosystemic shunt. In all dogs, both peripheral and portal venous blood samples were obtained at the time of surgical manipulation of the anomalous vessel. In six dogs, peripheral venous samples were obtained an average of 8.0 months after surgery. Five physically normal dogs without biochemical or histologic evidence of liver disease served as controls. Data analysis failed to demonstrate significant differences in peripheral and portal venous endotoxin concentrations between the control and study groups. Postoperatively five of six dogs showed a measurable reduction in peripheral venous endotoxin concentration over intraoperatively obtained values, but the differences were not statistically significant (P = 0.06). Based on results of this study it was concluded that systemic endotoxemia was not present in dogs with a single extrahepatic portosystemic shunt that were medically stable prior to surgery.

Acute renal failure in non-fulminant hepatitis A infection

A 7-year-old boy developed acute renal failure during the icteric phase of non-fulminant hepatitis A infection. He needed peritoneal dialysis for 3 days, which was followed by a rapid recovery in renal function which was normal when he was discharged 4 weeks later.

Endotoxin and the hyperdynamic circulation of portal vein-ligated rats

Humoral factors may be responsible for the hyperdynamic circulation seen in portal hypertension. Endotoxin, a peripheral arteriolar vasodilator, has been proposed to mediate this hemodynamic picture. We examined the pathogenic role of endotoxin in portal vein-ligated rats, a prehepatic portal hypertensive model with a well-developed hyperdynamic circulation. To this end, we (a) administered oral neomycin, a poorly absorbable antibiotic, at doses of 50 and 100 mg/day for 7 days and found no evident splanchnic hemodynamic effects of a 2-log-fold reduction of cecal aerobic bacterial flora as assessed by the radioactive microsphere technique in portal vein-ligated rats studied in the postanesthesia awake state; (b) assayed endotoxin in arterial samples using a quantitative limulus assay and found no evidence of endotoxinemia in PVL rats; (c) induced a state of endotoxin tolerance by repeated daily intraperitoneal injections of low-dose endotoxin and found no amelioration of the hyperdynamic state in portal vein-ligated rats. Our results do not support the hypothesis that endotoxin plays a major pathogenic role in the hyperdynamic circulation of this experimental model.

Prevention of postoperative complications in jaundiced rats. Internal biliary drainage versus oral lactulose

In an experiment mimicking a severe surgical trauma by deliberate renal ischemia, the postoperative outcome in jaundiced rats was studied. Intervention studies were performed with preoperative oral lactulose (to reduce endotoxin toxicity) or preoperative internal biliary drainage. Compared to control, obstructive jaundice in rats significantly reduced survival time (p less than 0.001) and enhanced renal impairment (p less than 0.001) after renal ischemia. Preoperative supportive therapy of jaundiced rats with oral lactulose increased survival time (p less than 0.01) but did not reduce deterioration of renal function. Preoperative internal biliary drainage proved to be superior, with a significant reduction of renal impairment (p less than 0.001) and an improved survival time (p less than 0.001). Our experiments provide further evidence that obstructive jaundice increases the complication rate following major surgical procedures. Based on our results in rats, we suggest that in obstructive jaundice preoperative internal biliary drainage is the supportive therapy of choice. However, if adequate drainage is not possible, oral treatment with lactulose may help reduce postoperative complications.

Necrotizing buccal and cervical fasciitis

A bite wound led to necrotizing fasciitis in the temporal space, the lateral pharyngeal space and the carotid sheath, indicative of a Streptococcus and Bacteroides infection, and was successfully treated with repeated incisions, radical debridement and antibiotic therapy.