Fibrinolysis in cholestatic jaundice

Fibrin deposition following bile duct injury limits fibrosis through an αMβ2-dependent mechanism

Coagulation cascade activation and fibrin deposits have been implicated or observed in diverse forms of liver damage. Given that fibrin amplifies pathological inflammation in several diseases through the integrin receptor αMβ2, we tested the hypothesis that disruption of the fibrin(ogen)-αMβ2 interaction in Fibγ(390-396A) mice would reduce hepatic inflammation and fibrosis in an experimental setting of chemical liver injury. Contrary to our hypothesis, α-naphthylisothiocyanate (ANIT)-induced liver fibrosis increased in Fibγ(390-396A) mice, whereas inflammatory cytokine expression and hepatic necrosis were similar to ANIT-challenged wild-type (WT) mice. Increased fibrosis in Fibγ(390-396A) mice appeared to be independent of coagulation factor 13 (FXIII) transglutaminase, as ANIT challenge in FXIII-deficient mice resulted in a distinct pathological phenotype characterized by increased hepatic necrosis. Rather, bile duct proliferation underpinned the increased fibrosis in ANIT-exposed Fibγ(390-396A) mice. The mechanism of fibrin-mediated fibrosis was linked to interferon (IFN)γ induction of inducible nitric oxide synthase (iNOS), a gene linked to bile duct hyperplasia and liver fibrosis. Expression of iNOS messenger RNA was significantly increased in livers of ANIT-exposed Fibγ(390-396A) mice. Fibrin(ogen)-αMβ2 interaction inhibited iNOS induction in macrophages stimulated with IFNγ in vitro and ANIT-challenged IFNγ-deficient mice had reduced iNOS induction, bile duct hyperplasia, and liver fibrosis. Further, ANIT-induced iNOS expression, liver fibrosis, and bile duct hyperplasia were significantly reduced in WT mice administered leukadherin-1, a small molecule that allosterically enhances αMβ2-dependent cell adhesion to fibrin. These studies characterize a novel mechanism whereby the fibrin(ogen)-integrin-αMβ2 interaction reduces biliary fibrosis and suggests a novel putative therapeutic target for this difficult-to-treat fibrotic disease.

Effect of preoperative biliary drainage on coagulation and fibrinolysis in severe obstructive cholestasis

GOALS

To evaluate the function of coagulation and fibrinolysis in cholestatic patients before and after preoperative biliary drainage (PBD).

BACKGROUND

Cholestasis owing to an obstructive biliary malignancy is associated with postoperative complications related to a proinflammatory state, an impaired hepatic synthesis function, and a potential derangement of hemostasis. Hence, PBD is advocated for cholestatic patients undergoing major surgery.

STUDY

Plasma coagulation and fibrinolytic parameters were assessed in 24 cholestatic patients and 10 controls. In 9 cholestatic patients, the parameters were reassessed at least 4 weeks after PBD.

RESULTS

Compared with controls, cholestatic patients showed lower concentrations (P<0.001) of plasma vitamin K-dependent factors II and VII, whereas prothrombin time, activated partial thromboplastin time, and factor V were unaltered. Thrombin generation was increased in cholestatic patients, as reflected by higher plasma concentrations of thrombin-antithrombin complexes and D-dimers. Fibrinolysis was significantly impaired as evidenced by low plasminogen activator activity (PAA) owing to an increase in plasminogen activator inhibitor -1). Elevated markers for thrombin generation thrombin-antithrombin decreased after PBD from 10.7±1.2 to 5.7±0.7 ng/mL (P<0.05). Additionally, impairment of fibrinolysis in cholestatic patients resolved after PBD (plasminogen activator inhibitor-1 levels decreased from 19±1 to 10±1 IU/mL and plasminogen activator activity increased from 82±3 to 110±4%, respectively). D-dimers remained unaltered after PBD, likely because of normalization of coagulation and fibrinolytic activity.

CONCLUSIONS

Obstructive cholestasis is associated with a procoagulant state, despite an impaired vitamin K-dependent coagulation factor synthesis. Virtually all alterations in coagulation and fibrinolysis were reversed by biliary drainage.

Endotoxaemia and hepatic injury in obstructive jaundice

To examine whether endotoxaemia contributes to the development of bile infarction and whether obstructive jaundice enhances endotoxin hepatotoxicity, the present study was undertaken in rats. The development of bile infarction and the elevation of serum transaminase activities in rats following ligation of the common bile duct were not prevented by administration of polymyxin B, neomycin, or lactulose, which have anti-endotoxin properties. Moreover, the morphological and functional changes in obstructive jaundice were not enhanced by administration of endotoxin. These data indicate that endotoxaemia does not contribute to the development of bile infarction. On the other hand, the administration of a small dose of endotoxin to rats with biliary obstruction--a dose which does not induce abnormalities of liver function tests or any morphological changes in the liver in non-jaundiced rats--led to focal hepatocellular coagulative necrosis and elevation of serum transaminase levels. These data indicate that endotoxin-induced hepatic injury is potentiated in obstructive jaundice.

Endotoxemia in obstructive jaundice. Observations on cause and clinical significance

Perioperative endotoxemia was detected in 24 of 40 patients who underwent operation for obstructive jaundice (bilirubin level greater than 5.8 mg/dl). Endotoxemia was associated with an increased admission serum bilirubin level (p less than 0.05) and white blood cell count (p less than 0.05) and a decreased hematocrit value (p less than 0.05), but there was no significant association with other established preoperative risk factors. Patients with preoperative endotoxemia had a decreased immunoglobulin M anti-J5 endotoxin titer (p less than 0.05) and a decreased serum bile acid concentration (p less than 0.05). Preoperative endotoxemia was associated with reduced creatinine clearance before and after operation (p less than 0.05). There was no association between endotoxemia and clinical sepsis, gram-negative infection, or small-bowel colonization. Patients who died had increased preoperative serum fibrin degradation products (p less than 0.05).

Reticulo-endothelial function in obstructive jaundice

A study of reticulo-endothelial function was performed in 30 patients with obstructive jaundice. Reticulo-endothelial phagocytic function, measured by the clearance of intravenous human micro-aggregated albumin, was significantly depressed in jaundiced patients compared with non-jaundiced controls (P less than 0.001). There was a significant correlation (P less than 0.001) between phagocytic function and plasma bilirubin level but not with transaminase or bile salt level. Phagocytic function was not related to the presence of malignancy, but was markedly reduced in patients with cholangitis. There was no reduction in hepatic sinusoidal blood flow, opsonin levels (fibronectin, IgG, complement) or serum opsonic activity to account for the reticulo-endothelial dysfunction.

Antithrombin III, plasminogen and alpha 2 antiplasmin in jaundice. Clinical usefulness and prognostic significance

In this prospective study, antithrombin III, plasminogen and alpha 2 antiplasmin which are synthetised by the liver were measured and compared with the Normotest, Thrombotest and fibrinogen concentrations in 92 consecutive jaundiced patients. Antithrombin III appeared to be the most discriminant coagulation test in differentiating hepatocellular from cholestatic jaundice. A high correlation was observed between antithrombin III, plasminogen and alpha 2 antiplasmin values suggesting that the liver synthesis of these parameters was closely linked. The prognostic significance of the blood coagulation tests in patients with jaundice has been studied. In parenchymatous liver disease, antithrombin III, plasminogen and alpha 2 antiplasmin were superior to the Normotest, Thrombotest and fibrinogen concentrations in predicting the prognosis of the patients at the time of admission. In cholestatic jaundice, however, none of the blood coagulation tests studied had a prognostic significance.

The fibrinolytic system in man

The existence of a system in the human body capable of inducing the dissolution of endogenous pathologically formed thrombi was appreciated in ancient times. Considered in detail in this article are the data that have elucidated the physiologic regulation of which plasmin formation is dependent on, the plasma concentration of plasminogen, availability of activators of plasminogen in the plasma and surrounding tissue environment, the concentration of naturally present inhibitors, and the existence of fibrin in the circulation. Important in this rapidly progressive scientific discipline is consideration of the factors which control the synthesis of the components of this proteolytic enzyme system. Recently abundant information has indicated that this plasminogen-plasmin proteolytic enzyme system can be utilized therapeutically. Knowledge of the mechanisms of this system has permitted identification of agents that can be exogenously administered to releave thrombotic obstruction to blood flow in the venous (pulmonary emboli, deep vein thrombosis) and arterial (peripheral and central vessels) circulatory systems. Particularly important is the demonstration that thrombolytic agents can directly attack and alleviate the immediate cause of acute myocardial infarction. As a result of the innovations in the present decade, it is evident that the plasminogen system can be advantageously employed to reverse the pathologic effects of all thrombotic diseases.

Endotoxemia, disturbance of coagulation, and obstructive jaundice

A prospective study of coagulation disturbances and endotoxemia in 42 patients having major pancreatic or biliary surgery was performed. Endotoxin, soluble fibrin, and fibrin degradation products were measured before and after operation in 28 patients with obstructive jaundice and in 14 nonjaundiced controls. In the control group there was one death and no unexplained fever or postoperative hemorrhage. The jaundiced group had more complications: seven deaths, nine episodes of fever, and six episodes of hemorrhage. Soluble fibrin was detected only in patients with obstructive jaundice, in whom it occurred in 38 percent before operation. Positive endotoxin assay was as common in control patients as in the jaundiced group, but in the latter endotoxin was associated (p less than 0.05) with increased FDP and soluble fibrin. Patients with endotoxin or increased FDP levels before operation for jaundice carry a poor prognosis (7 of 11 died). Preoperative bowel preparation in 16 of the jaundiced patients did not affect the outcome.

Some clinical features of liver cell failure: an appraisal of their causes

The mechanisms underlying the cause of the major clinical features of liver cell failure are reviewed. These include jaundice, fluid retention, hepatic encephalopathy, bleeding tendency, etc.

Endotoxaemia and renal failure in cirrhosis and obstructive jaundice

An investigation into the possible role of endotoxins in the pathogenesis of renal failure in cirrhosis and obstructive jaundice showed the two to be closely related. None of the patients with cirrhosis who had endotoxaemia had other evidence of Gram-negative infection at the time of the study, and the endotoxaemia was therefore probably due to impaired hepatic clearance of toxins normally absorbed from the gastrointestinal tract. In contrast, bacteriological evidence of Gram-negative infection was found in most of the patients with obstructive jaundice and endotoxaemia.