Purification and characterization of procoagulant in human urine

Urinary tissue factor: a potential marker of disease

Tissue factor (TF) is the main physiological initiator of blood coagulation and may be important in the biology of a variety of solid malignancies, particularly where angiogenesis is a critical factor. TF is frequently encrypted in the plasma membrane of cells in contact with blood, and is exposed only after stimulation by certain agonists. Cancer cells variably express TF and cancer cell lines which exhibit multidrug resistance contain more TF than parental cells. TF is increased in both tumour-associated macrophages and blood monocytes and has been implicated in abnormal coagulation activation seen in patients with inflammatory conditions and cancer. TF is also found in urine (uTF) in a lipid-associated form, probably of kidney origin. uTF levels can be assayed in a cost-effective manner and may be clinically important, particularly in patients with renal disorders and malignancy. uTF levels are not significantly affected by age, gender or cigarette smoking.

Development and validation of an assay for urinary tissue factor activity

BACKGROUND

Activation of blood coagulation is a common complication of cancer and inflammation in both humans and experimental animals. Increased production of tissue factor--the principal initiator of the coagulation process--by endothelial cells, monocytes, and macrophages has been implicated in these conditions.

AIM

To investigate whether urinary tissue factor (uTF) might reflect the state of monocyte/macrophage activation and be a useful diagnostic test.

METHODS

Urine was centrifuged at 51,000 g to sediment tissue factor containing membrane vesicles. The tissue factor was then solubilised in beta-octyl-glucopyranoside and assayed in a specific chromogenic assay adapted for use in microtitre plates.

RESULTS

The assay proved to be sensitive, specific, and reproducible. The normal range of uTF was relatively narrow and unaffected by age, sex, or cigarette smoking. Levels were not significantly influenced by storage of urine samples before assay or by the presence of fresh blood in the urine sample.

CONCLUSIONS

This method may have diagnostic application in the study of haemostatic activation in patients with cancer and other disease states.

Urinary procoagulant and fibrinolytic activity in human glomerulonephritis. Relationship with renal function

Fibrin deposition in kidney is a common event in some forms of human and experimental glomerulonephritis, and is thought to result from local activation of blood coagulation and/or impaired removal by the fibrinolytic system. We studied the urinary procoagulant and fibrinolytic activities in 46 patients with renal disease (26 with IgA nephritis, 13 with other forms of glomerulonephritis and 7 with non-inflammatory kidney disease) and in 15 matched healthy subjects, as possible indicators of the coagulation-fibrinolysis balance in kidney. Procoagulant activity was slightly but not significantly increased in patients with serum creatinine levels higher than 1.5 mg/dl (group II) as compared with patients with normal creatinine (group I) and controls. It was identified as tissue factor by biological criteria (dependence on factor VII). Fibrinolysis studies showed that both plasminogen activator activity and urokinase antigen were significantly lower in group II than in group I patients and controls (P less than 0.0005). Reduced fibrinolytic activity in patients' urine was due to decreased excretion of urokinase since no inhibitor was detected by both fibrin autography and functional assay. No differences were found between patients and controls in plasma fibrinolytic activity, plasminogen activator inhibitor, and procoagulant activity of blood monocytes. The urinary changes in severe renal disease may reflect an unbalance of the coagulation-fibrinolysis equilibrium in kidney and might be of pathogenetic and clinical relevance.

Urinary tissue factor activity in colorectal disease

Procoagulant activity (PCA) in normal urine has been recognized for over 50 years. Although tissue factor (TF) is produced by certain tumours, and is increased in both tumour-associated macrophages and blood monocytes, the possibility that it might also be increased in urine has not been studied in patients with cancer. We have measured urinary PCA in hospital controls without inflammatory or neoplastic disease (n = 79), in patients with rheumatoid arthritis (n = 8), inflammatory bowel disease (n = 19), colorectal cancer (n = 70) and in patients undergoing colonoscopy (n = 50). Urinary PCA was higher (P less than 0.001) in patients with colorectal cancer and inflammatory bowel disease than controls or patients with rheumatoid arthritis. Fourteen (88 per cent) out of 16 colonoscopy patients subsequently found to have carcinoma or inflammatory bowel disease had levels above the control upper quartile, compared with 8 (24 per cent) out of 34 with normal colonoscopy (P less than 0.001). TF inhibitors confirmed the nature of the PCA and Western blotting studies indicated a urinary TF molecular weight of approximately 38,000. These studies provide further evidence of abnormal haemostasis in malignancy and suggest that determination of urinary TF may provide a useful screening test in patients undergoing colonoscopy.

Procoagulant activity in normal human urine associated with subcellular particles

Procoagulant activity (PCA) in normal human urine was found to be sedimented by centrifugation at X 100,000g. Therefore, studies were done to identify the structures associated with the procoagulant activity. Transmission electron microscopy of the X 100,000g pellet revealed numerous membrane-bound vesicles as well as fibrous material. Filtration of normal urine through a 0.2-micron filter removed more than 90% of the procoagulant activity. Scanning electron microscopy of the filter surface revealed 0.1 to 1.1 micron particles and fibrous material. By centrifugation at pH 3 and 5 the fibrous material and particles were separated. The procoagulant activity remained with the particles in each case. The fibrous material was shown to be Tamm-Horsfall protein by SDS-PAGE and Western blotting using anti-Tamm-Horsfall protein serum. Purified Tamm-Horsfall protein itself was not procoagulant. Therefore, PCA in normal human urine is associated with particles 0.1 to 1.1 micron in diameter which appear to be lipid membranes in various arrangements.

Urinary procoagulant behaves as tissue factor by promoting factor VIIa-catalyzed activation of factor X

We purified the urinary procoagulant from frozen human urine by introducing phenyl-Sepharose hydrophobic chromatography. By this method, the apoprotein of the procoagulant and the lipid-like substance were separately recovered. Upon reassociation with the lipid-like substance or exogenous crude phospholipids, the apoprotein accelerated factor VIIa-catalyzed activation of factor X, probably by forming a stoichiometric complex with the catalytic enzyme. Thus the procoagulant was confirmed to be a tissue factor by its mode of participation in the blood coagulation mechanism.

Localization of urinary procoagulant in the human kidney

By the indirect immunofluorescent and immunoenzymatic techniques with monospecific antiserum against urinary procoagulant (a tissue factor which accelerates blood coagulation), we found the urinary procoagulant in the kidney distributed to the loop of Henle and distal convoluted tubules. In these areas urinary procoagulant was found in association with the luminal and intercellular borders as well as in the cytoplasm of epithelial cells. Both the descending and ascending limbs of Henle were equally stained. The cytoplasmic staining was patchy in distribution among cells of distal tubules and was predominantly localized in the supranuclear areas. Glomeruli, the proximal tubular cells, the vascular wall, and the interstitium were not stained. There was, however, fluorescent staining along the epithelial layers of the Bowman's capsule, which was observed only in the frozen sections. Casts in the distal tubules were also positively stained. These findings suggest that urinary procoagulant is synthesized in the epithelial cells of these particular parts of nephron and is secreted into urine, although its physiologic roles and pathologic significance are not entirely known.