Progress curve analysis of microtitre plate plasma clotting assays. Assessment of tissue factor levels.

MTP plasma clotting assays monitor the time course of fibrin formation in re-calcified plasma by absorbance measurements and are increasingly used as alternatives to traditional one-point clot time assays employed in clinical laboratories to detect thrombotic disorders. The parameters derived from these analyses are analogous to thromboelastography viz. time, rate and maximum extent of clot formation. The derived parameters, based on the whole course of the clotting reaction are more robust, informative and quantitative than single-point clot time assays. However, the parameters themselves are usually obtained arbitrarily by crude graphical analysis of subjectively selected points of progress curves. The current work aimed to investigate the sensitivity and reproducibility of an MTP clotting assay and examine its suitability for measuring tissue factor (TF) levels in cell culture medium and patient urine. The results demonstrate that progress curves can be analysed by fitting a logistic equation, derived from a simplified autocatalytic clot formation model. The parameters, maximum amplitude (Fm), rate constant (k), time to half-maximum amplitude (tm) and maximum rate of clot formation (vm), fit a power curve showing limiting effects with increasing TF concentration. Log/log plots of tm and k against TF concentration provide standard curves for assessment of unknowns.

Urinary pro-thrombotic, anti-thrombotic, and fibrinolytic molecules as biomarkers of lupus nephritis.

OBJECTIVE: This study evaluates the utility of urinary pro-thrombotic molecules such as tissue factor (TF), anti-thrombotic molecules such as tissue factor pathway inhibitor (TFPI), and fibrinolytic molecules such as plasmin and d-dimer as biomarkers of lupus nephritis (LN). METHODS: Urine samples from 113 biopsy-proven LN patients (89 active LN and 24 inactive LN), 45 chronic kidney disease patients, and 41 healthy controls were examined for d-dimer, plasmin, TF, and TFPI levels by ELISA. The area under the receiver operating characteristic curve (AUC) analysis, multivariate regression analysis, and Bayesian network analysis were performed to assess the diagnostic value of the assayed molecules in LN. RESULTS: Although urinary d-dimer, plasmin, TF, and TFPI were all elevated in active LN compared to all control groups, and correlated with rSLEDAI and SLICC RAS disease activity indices, urine plasmin emerged as the strongest independent predictor of eGFR and renal disease status, by multivariate regression analysis and Bayesian network analysis. Whereas urine plasmin discriminated active LN from inactive disease with an AUC of 0.84, the combination of urine plasmin and TFPI discriminated ALN from ILN with an AUC of 0.86, with both surpassing the specificity and positive predictive value of traditional markers such as anti-dsDNA and complement C3. CONCLUSION: Both thrombogenic and thrombolytic cascades appear to be upregulated in lupus nephritis, with proteins from both cascades appearing in the urine. Of the coagulation cascade proteins surveyed, urine plasmin emerges as the strongest predictor of eGFR and clinical renal disease in patients with LN.

Signal Transduction Peptide of Tissue Factor Phosphorylated at Ser258 and the Unphosphorylated STP in Urine Are Potential Biomarkers for Bladder Cancer.

BACKGROUND: Procoagulant activity attributed to tissue factor (TF, CD142) bound to lipid microvesicles has previously been shown to be elevated in urine of patients with various solid cancers. The phosphorylation of the C-terminal signal transduction peptide (STP) at Ser253 and Ser258 has been determined to be important for the formation of TF-microvesicles. The purpose of this work was to investigate the marker potential of the TF-STP domain in urine of patients with cancer using immunologic methods to quantitate unphosphorylated TF and TF phosphorylated at Ser253 and Ser258. MATERIALS AND METHODS: We developed monoclonal and polyclonal antibodies directed against the 3 C-terminal STP species of TF and constructed 3 enzyme-linked immunosorbent assays (ELISAs) that specifically recognize unphosphorylated TF and TF phosphorylated at either Ser253 or Ser258. As proof of principle, a preliminary pilot study with stored Biobank-sourced urinary specimens from 45 healthy individuals and 38 patients with bladder cancer were studied using these ELISAs. RESULTS: We report that all 3 species of TF were found in the urine. Two species, TF-pSer258 and unphosphorylated TF, were significantly elevated in the cohort with bladder cancer. The sensitivity of TF-pSer258 by the receiver operator characteristic technique was 86.8%, with a specificity of 97.8% at a cutoff value of 0.55 ng/mL. Using a simplified sample preparation method for the ELISAs on the same clinical specimens, the sensitivity of TF-pSer258 was 86.8%, with a specificity of 93.3% at a cutoff value of 0.53 ng/mL. The unphosphorylated TF species was significantly elevated in later stage bladder cancer with best results seen for the unfractionated preparation technique (95% confidence interval, 10.55-15.74; N = 20) but not early stage non-muscle-invasive bladder cancer (95% confidence interval, 4.71-10.73; N = 18; P < .02). CONCLUSIONS: The development of these new ELISAs allows the quantitation of the urinary biomarkers TF-pSer258 and unphosphorylated TF, which may lead to a new diagnostic approach to the early detection of bladder cancer and warrant further investigation in a prospective trial.

Urinary tissue factor in glomerulonephritis: a potential marker of glomerular injury?

AIM: To investigate the significance of urinary tissue factor (uTF) concentrations in patients with glomerulonephritis. METHODS: Urine samples were collected from normal subjects (n = 57), patients with uncomplicated renal stones (n = 30), and patients with glomerulonephritis (n = 150). Samples were then centrifuged and the pellets solubilised in n-octyl-beta-glucopyranoside. uTF concentrations were determined using a one stage kinetic chromogenic assay. RESULTS: The uTF concentration was higher in patients with glomerulonephritis than in normal controls (p < 0.01) or in patients with renal stones (p < 0.05). uTF activity correlated with the protein creatinine index (PCI, r = 0.41, p < 0.001) and seven patients with glomerulonephritis and a PCI < or = 0.1 g/mmol had raised uTF. Glomerulonephritis patients were subdivided into two groups depending on the PCI: < 0.2 g/mmol creatinine (mild to moderate proteinuria, group I) and > or = 0.2 g/mmol creatinine (heavy proteinuria, group II). In group I, uTF concentrations were higher in patients with either immune complex (IC) glomerulonephritis (p < 0.01) or non-IC (p < 0.05) glomerulonephritis than in normal controls. In group II, the IC glomerulonephritis group had higher uTF concentrations than normal controls (p < 0.001) or patients with renal stones (p < 0.01); and non-IC glomerulonephritis patients had higher uTF than normal controls (p < 0.01). When the glomerulonephritis groups were divided into broad WHO subtypes, the significance level varied with the type of glomerulonephritis. CONCLUSIONS: uTF is increased in patients with glomerulonephritis, and its concentration may reflect the aetiopathogenesis of glomerulonephritis.

Effect of kidney function and disease status on urinary tissue factor measurements.

AIM: To investigate factors that influence urinary tissue factor (uTF) measurements: glomerular permeability and filtration, tubular function, haematuria, and urine bacterial growth. METHODS: uTF, protein creatinine index, glomerular filtration rate, retinol binding protein, N-acetyl-beta-D-glucosaminidase (NAG) and urinary haemoglobin (uHb) were measured in patients with hypertension, diabetes mellitus and nephrotic syndrome (n = 342), tubulo-interstitial disease (n = 50), and haematuria of uncertain cause (n = 50); measurements were also made in urine samples from healthy subjects for "simulated" haematuria (n = 6) and bacterial growth (n = 4) studies. RESULTS: There was a weak correlation of uTF with glomerular permeability and filtration (protein creatinine index and glomerular filtration rate) and with markers of tubular function (retinol binding protein and NAG). uTF concentrations were not affected by the presence of blood or bacteria in the urine sample. CONCLUSION: uTF concentrations are relatively stable. This is an important finding if the assay is to be used in clinical practice.

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 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.

Urinary tissue factor levels in patients with bladder and prostate cancer.

AIMS: Coagulation activation is a recognized complication of cancer in which increased tissue factor (TF) is implicated. TF can be detected in urine (uTF). This study assesses uTF levels in benign and malignant urological disease and correlates the results with conventional markers of tumour progression. METHODS: Using a simple and reproducible kinetic chromogenic assay, we determined uTF levels in controls (normal volunteers (n = 57) and patients with renal stones (n = 30)), benign and malignant bladder (n = 75) or prostate (n = 106) disease and in patients with or without recurrent bladder cancer (n=30). Each benign disease group was stratified as inflammatory (cystitis or prostatitis) or non-inflammatory (negative cystoscopy following haematuria or benign prostatic hypertrophy). RESULTS: The controls and the benign non-inflammatory results were indistinguishable. The malignant and inflammatory groups showed raised uTF levels over controls (P<0.001 bladder and P<0.01 prostate). The difference between malignant and benign inflammatory disease was only significant for the bladder group. uTF levels were significantly related to histological tumour grading, prostate serum specific antigen, static bone scan images and recurrence status. CONCLUSIONS: uTF levels can distinguish, statistically but not without overlap, patients with malignancy from normal controls and benign non-inflammatory conditions. Discrimination between inflammatory and malignant disease has only been demonstrated in the bladder. uTF levels showed a significant association with markers of tumour progression or metastasis and may be useful in predicting bladder tumour recurrence.

The clinical value of tissue factor assays.

Tissue factor (TF) is now considered to be the primary physiologic activator of the blood coagulation system. Coupled with recent advances in our understanding of the biochemistry of TF this has heightened interest in measuring aspects of TF activity in disease states. Expression of TF by blood monocytes in various diseases is an established trigger for intravascular coagulation and there is now a considerable body of experience with its measurement. This has considerable clinical potential although more widespread application awaits a consensus on the most appropriate methodologic approach to its measurement. TF can be detected in urine and may reflect the activation state of renal macrophages. Urinary TF is increased in cancer and could have diagnostic and prognostic value in a variety of malignant diseases. Finally, it is now possible to measure soluble TF in plasma. One such assay is commercially available and is technically simple to perform. The clinical value of such assays, however, must await better understanding of the source and function of soluble TF in plasma.

[Urinary level of tissue factor and its procoagulant activity in patients with type 2 diabetes].

OBJECTIVE: To examine the urinary level of tissue factor (uTF) and its procoagulant activity (PCA) in patients with diabetes mellitus, and explore the relationship between uTF and renal damage in diabetes mellitus. METHODS: Eighty-six patients with type 2 diabetes mellitus were divided into 3 groups according to urine albumin excretion (UACR), namely normal albuminuria group, microalbuminuria group and macroalbuminuria group. The levels of uTF, PCA, blood urea nitrogen (BUN), serum creatinine (CRE), serum cystatin C (CYSC), glycohemoglobin A1c (HbA1c), and high-sensitivity C-reactive protein (hs-CRP) were measured in all the patients and 21 healthy controls. RESULTS: Compared with normal control, the diabetic patients showed significantly increased levels of uTF and PCA. The urinary TF-PCA was positively correlated to BUN, CYSC, CRE, UACR, fasting glucose and hs-CRP, but not to uTF; only hs-CRP, UACR were positively correlated to uTF. CONCLUSION: uTF is probably implicated in the development and progression of diabetic nephropathy.

Tissue factor and its inhibitor in human non-crescentic glomerulonephritis--immunostaining vs plasma and urinary levels.

BACKGROUND: Tissue factor (TF)-the most potent trigger of coagulation and emerging antiapoptotic, proliferative and angiogenic factor, along with its principal inhibitor (tissue factor pathway inhibitor, TFPI) are known to be involved in crescentic glomerulonephritis (GN). We studied the relationship between plasma and urinary levels as well as renal biopsy immunostaining of TF and TFPI antigens with reference to some clinical parameters in human chronic non-crescentic GN. METHODS: We examined plasma and urinary levels of TF and total TFPI (pre-biopsy, ELISA) and the intensity of TF, TFPI 1 and TFPI 2 staining (immunoperoxidase histochemistry) in kidney biopsy specimens from 30 chronic GN patients. RESULTS: Plasma and urinary TF (uTF) were higher in patients than in 18 healthy individuals. In normal kidneys, TF and TFPI 1/2 antigens were undetectable in glomeruli while a distinct staining of both TFPI variants was observed in tubules and interstitial microvessels. In diseased kidneys, TF was strongly expressed in glomeruli but was undetectable in tubules. In contrast, staining for TFPI 1/2 was observed in glomeruli and tubules. Neither plasma nor urinary levels of the markers correlated with the intensity of TF and TFPI 1/2 staining in biopsy specimens. uTF was significantly associated with creatinine clearance (R = 0.489, P = 0.006) and urinary TFPI (R = 0.554, P = 0.014), and tended to be lower in proliferative vs non-proliferative GN [83 (0-617) vs 281 (10-805) pg/ml; P = 0.06]. CONCLUSION: The intrarenal TF/TFPI system is profoundly disturbed in chronic GN. Plasma and urinary concentrations of TF and TFPI probably do not reflect genuine activity of the disease, likely due to a confounding effect of kidney insufficiency. uTF measurement seems to be helpful in initial identification of proliferative GN, yet further studies are required to validate its use as a marker of glomerular injury in chronic GN.

Urinary procoagulant activity and tissue factor levels in patients with diabetes mellitus.

We characterized a factor important for the normal procoagulant activity in human urine and measured urinary tissue factor (TF) and thrombomodulin (TM) levels in patients with diabetes mellitus (DM). Urine shortened normal plasma-based clotting time, which is inhibited by antibody to the human TF. TF in urine presents in membrane-nonassociated and associated forms. The urine TF antigen levels in DM patients were significantly lower than those in healthy subjects, particularly in DM patients without retinopathy. Levels of TM in patients with DM and normal subjects were similar. Although urinary TF might be necessary to repair tissue injury of damaged sites in the excretory pathway of urine, the clinical relevance of the reduced TF in the urine needs further investigation.

Urinary tissue factor levels in transitional cell carcinoma of the bladder.

Production of procoagulant activity by host and tumour cells may be increased in patients with cancer. Using a simple chromogenic assay, we have determined urinary tissue factor (TF) levels in patients presenting with transitional cell carcinoma of the bladder (TCC, n = 63), normal controls (n = 20) and patients with benign prostatic hypertrophy (BPH, n = 35). In addition, a separate cohort of patients undergoing endoscopic surveillance for superficial bladder cancer were studied to determine whether there was any difference in levels in those with recurrent disease compared to those with normal cystoscopies. Urinary TF activity was higher in TCC compared to controls (p less than 0.001) and patients with BPH (p less than 0.05). In patients undergoing check cystoscopy, those with recurrent disease (n = 32) had higher levels (p less than 0.01) than those with normal examinations (n = 21). It is concluded that urinary TF levels are elevated in bladder cancer and that this reflects disease activity in those at risk of recurrent superficial disease.

Functional and structural properties of urinary tissue factor.

BACKGROUND: We have previously explored the clinical significance of urinary tissue factor (uTF) in patients with glomerulonephritis (GN) and malignancy. However, the functional and structural properties and putative cell of origin of uTF are poorly documented. In these studies we investigate these aspects of uTF. METHODS: Functional and structural properties of uTF were investigated using a one stage kinetic chromogenic assay, an enzyme-linked immunoabsorbent assay (ELISA) and transmission electron microscopy (TEM) on urine samples collected from healthy controls (n=69). The distribution of uTF and anionic phospholipid in the kidney were studied in sections from normal areas of nephrectomy specimens, using an immunoperoxidase technique. These were stained for tissue factor (TF) antigen and recombinant Annexin V. RESULTS: We found uTF to be present on subcellular particles as visualized by TEM. These particles contained anionic phospholipid as evidenced by binding to Annexin V fluorescein isothiocyanate (FITC). Although TF is present in urine in a functional and antigenic form no association was observed between the two. Using immunoperoxidase-based techniques, the cytoplasm of both distal and proximal tubules (but not glomerular cells) was positive for TF antigen and Annexin V. CONCLUSION: uTF is found on subcellular particles which provide lipid for its functional activity. Both uTF and its associated vesicles are found in the renal tubular cells.

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.