Endotoxaemia and renal failure in cirrhosis and obstructive jaundice

Endotoxin, reticuloendothelial function, and liver injury

The concept that relates intestinal bacteria and their toxins as a common pathway of liver injury by toxic agents has interested investigators for a long period. Recently, a number of studies in experimental animals and in patients with liver disease support this contention, and are reviewed. Evidence is presented to suggest that: (a) function of the sinusoidal cells is critical to integrity of the hepatocyte; (b) damage to these lining cells by several agents may be the initial injury leading to decreased ability of the liver to detoxify endotoxin (LPS); (c) following this primary injury to Kupffer and endothelial cells, LPS causes damage at amounts which are ordinarily innocuous and may represent a final pathway of liver necrosis; (d) "spillover" of LPS may lead to systemic manifestations of liver disease, and (e) modification of endotoxin toxicity or absorption may protect against several acute and chronic liver injuries.

Renal failure in fulminant hepatic failure and terminal cirrhosis: a comparison between incidence, types, and prognosis

Forty patients with terminal cirrhosis and 40 patients with fulminant hepatic failure-all consecutively admitted-were studied with regard to incidence, types, and prognosis of complicating renal insufficiency. Renal failure was considered present when the serum creatinine was greater than 0.20 mmol/l. Of the patients with cirrhosis 26 (65%) developed renal failure. In 15 the type was functional, in three due to acute tubular necrosis, and in eight indeterminable. Of the patients with fulminant hepatic failure 22 (55%) had renal insufficiency; of these 13 had functional renal failure, five acute tubular necrosis, and in four the type was indeterminable. In both categories of patients, renal failure was equally frequent among patients with or without gastrointestinal bleeding and with or without ascites or diuretic therapy. The biochemical tests of liver function were similar in patients with or without renal failure in both categories. The mean renal blood flow in seven unselected patients with fulminant hepatic failure was reduced in the same order as previously observed in patients with cirrhosis. In terminal cirrhosis the mortality rate was 88% in the presence of renal failure, 71% in its absence (p greater than 0.05), while the same figures in fulminant hepatic failure were 100% and 67% (p less than 0.05). The incidence, relative frequency, and prognosis of renal failure were not different in the two conditions, indicating identical pathophysiological circumstances.

[Hepato-renal syndrome (author's transl)]

The hepato-renal syndrome is defined as potentially reversible functional renal failure associated with acute fulminant hepatitis or, more often, with advanced chronic liver failure. It is characterized by oliguria, azotemia, retention of sodium and water with formation of ascites, and hyponatremia. While urinary sodium concentration of less than 10 mEq/l reflects intact tubular sodium absorption, the kidney lacks the ability for adequate free-water generation. This condition must be separated from specific renal diseases which may arise during the course of intra-or extrahepatic diseases and which must be classified accordingly. Pathophysiological aspects of the hepa-to-renal syndrome include hemodynamic factors, such as changes in intrarenal blood flow distribution in the presence of elevated intrarenal and reduced peripheral vascular resistance. The functional relationship of vasoconstrictor, sodium retaining, and anti-diuretic hormones (e.g., renin-angiotensin, aldosterone, and vasopressin) to vasodilator, diuretic, and natriuretic hormonal factors (e.g., prostaglandins, kinins, and natriuretic hormone) may be altered as well. Finally, a pre- and intrahepatic spillover resulting in decreased endotoxin clearance must be considered. Due to the lack of understanding of their complex interactions, so far pharmacological and therapeutic approaches remained ineffective to correct at least some of these factors. Today, recovery from hepato-renal syndrome will, therefore, mainly depend on the course of the underlying liver disease.

The value of polymixin B in endotoxaemia due to experimental obstructive jaundice and mesenteric ischaemia

The role of polymixin B in endotoxaemia due to obstructive jaundice and mesenteric ischaemia has been examined. Rats made jaundiced by common bile duct ligation were challenged with intragastric endotoxin. Rats given polymixin B infusions had improved survival (11/15) compared with controls (4/14). Mesenteric ischaemia was induced in rats by clipping the mesenteric artery. Limulus assay revealed marked endotoxaemia in controls. Polymixin B infusions reduced the degree of endotoxaemia. Pre-treatment with non-absorbable intestinal antibiotics markedly reduced endotoxaemia. Polymixin B infusions gave no advantage of survival (3/10) compared with controls (2/10), but all animals pre-treated with intestinal antibiotics survived (12/12). The difference in results found between obstructive jaundice and mesenteric ischaemia may be due to different degrees of endotoxaemia. Polymixin B may have a place in the prophylaxis of endotoxaemia in clinical obstructive jaundice.

Kupffer cell phagocytosis in relation to BSP clearance in liver and inflammatory bowel diseases

Experience using microaggregated human serum albumin for a Kupffer cell phagocytic capacity "stress test" in patients with liver and inflammatory bowel diseases is described. Each result has been related to a 1-hr BSP clearance in order to account for variations in liver blood flow. Kupffer cell clearances are reduced in proportion to BSP clearance in obstructive jaundice and in secondary biliary cirrhosis but are increased in patients with chronic hepatocellular inflmmation. Conversely Kupffer cell phagocytosis is often depressed in patients with alcoholic hepatitis. In Crohn's disease or ulcerative colitis RES function is normal unless patients are receiving corticosteroid suppression.

Renin-angiotensin-aldosterone system in cirrhosis

According to traditional concepts, ascites formation and portal hypertension in cirrhosis lead to a deficit in the 'effective' extracellular fluid (ECF) and blood volumes respectively. The renin-angiotensin-aldosterone (RAA) system is thus stimulated and the kidneys retain fluid as a homeostatic mechanism to restore the ECF and blood volumes. Recent studies, however, show that approximately two-thirds of patients with ascites do not have a stimulated RAA system and in those without clinical evidence of fluid retention the RAA system is actually suppressed. These findings are incompatible with the concepts of reduced effective ECF and blood volumes. Despite the fact that most patients retaining sodim and accumulating ascites have a normal plasma aldosterone concentration, other evidence strongly suggests a dominant role for aldosterone in the regulation of renal sodium excretion. There might therefore be an increased renal tubular sensitivity to aldosterone in cirrhosis. For the one-third of patients with ascites who do have a stimulated RAA system this may well be a response to reduced effective ECF and/or blood volumes in accord with traditional concepts.

Diuretic-induced renal impairment without volume depletion in cirrhosis: changes in the renin-angiotensin system and the effect of beta-adrenergic blockade

In 4 patients with cirrhosis and ascites, diuretic therapy resulted in an impairment of renal function that was associated with a rise in plasma renin activity (PRA). In 3, this occurred in the absence of volume depletion. When diuretics were discontinued, renal function returned to normal. beta-adrenergic blocking drugs were then given to suppress renin secretion and diuretics restarted. On this occasion, impairment of renal function did not occur. In 2 further patients, administration of beta-adrenergic blockers during a period of diuretic-induced renal impairment resulted in an improvement in renal function. Although these findings may indicate that diuretic-induced renal impairment in cirrhosis is at least partly due to activation of the renin-angiotensin system, in another group of patients a diuretic-induced rise in PRA was not associated with a deterioration in renal function.

The contribution of gut-derived endotoxins to liver injury

The liver serves as the key organ for the removal and detoxification of bacterial endotoxins that are continously absorbed in small amounts from the gastrointestinal tract. This paper postulates that liver injury impairs this detoxification process leading to further liver damage and systemic effects as well. Evidence is reviewed to support the contention that endotoxin may be a major common pathway for liver injury by a variety of agents, and methods of reducing endotoxicity of gut origin are proposed. Finally, a new solid phase radioimmunometric assay for E. coli 026 is described and its usefulness as a gut marker suggested.

Renal and cerebral blood flow in experimental liver failure in the pig

The renal and cerebral blood flow was measured in six pigs after total devascularization of the liver. The animals died 21 to 26 h after the operation, with biochemical and electroencephalographic changes compatible with liver failure. The renal blood flow increased slightly, from 2.12 to 2.61 ml.g-1.min-1, throughout the period of observation but did not differ significantly from that of the controls. Conversely, the cerebral blood flow decreased 38%, from 1.30 to 0.80 ml.g-1.min-1, p less than 0.05. The results failed to confirm a simultaneous decrease in cerebral and renal blood flow due to false neurotransmitters in liver failure, as previously suggested. The results do not support the suggested hypothesis that a substance produced by the liver is essential for renal function and perfusion, nor can they confirm that vasoactive material from the gut is responsible for the renal hypoperfusion in liver failure. The absence of renal hypoperfusion in the present preparation might be due to the exclusion of the failing liver from the circulation, giving indirect evidence to the theory that the vasoactive agent(s) responsible for the renal hypoperfusion in liver failure originates in the failing liver itself.

Spectrum of renal tubular damage in renal failure secondary to cirrhosis and fulminant hepatic failure

Measurements of urinary lysozyme were used to evaluate renal tubular integrity in 34 patients with cirrhosis or fulminant hepatic failure who had developed renal impairment. In 18 of the patients the lysozyme values were normal but in the remaining 16 were increased, supporting previous concepts that renal failure complicating hepatocellular disease may occur both without and with tubular necrosis. The lysozyme values were inversely related to the creatinine clearance, suggesting that the development of tubular necrosis may be determined by the level of renal perfusion. The validity of simpler laboratory tests often used to assess renal tubular integrity--namely, the urine sodium concentration, the urine:plasma osmolality ratio, and casts in the urine sediment--was evaluated by comparison with the lysozyme measurements. The urine sodium concentration was of most value and the findings in the sediment were of no value at all.

Renal blood flow in cirrhosis: relation to systemic and portal haemodynamics and liver function

The RBF was measured by means of the 133Xe washout method in seventy patients with cirrhosis. The average RBF in controls was 3.72 ml/g-min compared with 2.34 in the patients without ascites, 1.82 in the decompensated patients, 1.47 in the patients with azotaemia and 1.13 in the patients with additional oliguria. The RBF was not significantly correlated to changes in the systemic or portal haemodynamics. Likewise it was not correlated to any biochemical test of liver function except the serum albumin concentration (P less than 0.01). From the present results it can be concluded that a reduction in RBF in cirrhosis frequently is present before sodium and water retention is clinically evident and before laboratory proof of impairment of renal function, and that a subnormal serum albumin concentration may be a factor among several leading to renal hypoperfusion in cirrhosis.