Exploring the Role of Antithrombin in Nephrotic Syndrome-Associated Hypercoagulopathy: A Multi-Cohort Study and Meta-Analysis.

BACKGROUND: Nephrotic syndrome is associated with an acquired hypercoagulopathy that is thought to drive its predisposition for venous thromboembolism. Previous studies have suggested that urinary antithrombin (AT) loss leading to acquired AT deficiency is the primary mechanism underlying this hypercoagulopathy, but this hypothesis has not been directly tested. The objectives of this study were to test the influence of AT levels on hypercoagulopathy in nephrotic syndrome patient samples and perform meta-analyses to evaluate the likelihood of AT deficiency in patients with nephrotic syndrome. METHODS: Samples from three independent nephrotic syndrome cohorts were analyzed. AT antigen and activity assays were performed using ELISA and amidolytic assays, respectively. Plasma thrombin generation, albumin, and urine protein-to-creatinine ratios were determined using established methods. Meta-analyses were performed by combining these new data with previously published data. RESULTS: AT levels were not consistently related to either plasma albumin or proteinuria. AT was quantitatively related to hypercoagulopathy in adult nephrotic syndrome, whereas AT activity was inconsistently associated with hypercoagulopathy in childhood nephrotic syndrome. Notably, hypercoagulopathy did not differ between patients with normal AT levels and those with levels below the threshold used to define clinical AT deficiency (<70%). Moreover, ex vivo AT supplementation did not significantly alter hypercoagulopathy in AT-deficient plasma samples. The meta-analyses demonstrated that AT deficiency was not a uniform feature of nephrotic syndrome and was more common in children than adults. CONCLUSIONS: These data suggest that AT deficiency plays only a limited role in the mechanisms underlying the acquired hypercoagulopathy of nephrotic syndrome. Moreover, AT deficiency was not present in all patients with nephrotic syndrome and was more likely in children than adults despite the higher risk for venous thromboembolism in adults than children.

Differential urinary proteomics analysis of myocardial infarction using iTRAQ quantification.

Myocardial infarction (MI) is a disease characterized by high morbidity and mortality rates. MI biomarkers are frequently used in clinical diagnosis; however, their specificity and sensitivity remain unsatisfactory. Urinary proteome is an easy, efficient and noninvasive source to examine biomarkers associated with various diseases. The present study, to the best of the authors' knowledge, is the first to examine the urinary proteome using the isobaric tags for relative and absolute quantitation (iTRAQ) technology to identify potential diagnostic biomarkers of MI. The urinary proteome was analyzed within 12 h following the first symptoms of early­onset MI and at day 7 following percutaneous coronary intervention via iTRAQ labeling and two­dimensional liquid chromatography­tandem mass spectrometry. Candidate biomarkers were validated by multiple reaction monitoring (MRM) analysis. A total of 233 urinary proteins were differentially expressed. Gene enrichment analysis identified that the urinary proteome in patients with MI was associated with atherosclerosis, abnormal coagulation and abnormal cell metabolism. In total, 12 differentially expressed urinary proteins were validated by MRM analysis, five of which were associated with MI for the first time in the present study. Binary logistic regression analysis suggested that the combination of five urinary proteins (antithrombin­III, complement C3, α­1­acid glycoprotein 1, serotransferrin and cathepsin Z) may be used to diagnose MI with 94% sensitivity and 93% specificity. In addition, the protein expression levels of three proteins were significantly restored to normal levels following surgical treatment. The verified candidate biomarkers may be used for the diagnosis of MI, and for monitoring the disease status and the effects of treatments for MI. The present results may facilitate future clinical applications of the urinary proteome to diagnose MI.

Analysis of the differential urinary protein profile in IgA nephropathy patients of Uygur ethnicity.

BACKGROUND: IgA nephropathy (IgAN) is one of the most common forms of idiopathic glomerular diseases and might lead to end-stage kidney disease. Accurate and non-invasive biomarkers for early diagnosis are required for early intervention and consequent therapy for IgAN patients. Because variance in the disease incidence and predisposing genes of IgAN has been detected among different ethnicities, the ethnicity factor should be considered in IgAN biomarker discovery. The differences in the protein profiles and pathological mechanisms of IgAN in patients of Uygur ethnicity need to be clearly illustrated. METHODS: In this study, we used urinary proteomics to discover candidate biomarkers of IgAN in patients of Uygur ethnicity. The urinary proteins from Uygur normal control and Uygur IgAN patients were extracted and analyzed using 2D-LC-MS/MS and isobaric tags for relative and absolute quantitation (iTRAQ) analysis. RESULTS: A total of 277 proteins were found to be differentially represented in Uygur IgAN compared with the respective normal controls. The bioinformatics analysis revealed that the immune response, cell survival, and complement system were activated in Uygur IgAN. Many differentially expressed proteins were found to be related to nephropathy and kidney injuries. Four candidate biomarkers were validated by Western blot, and these results were consistent with the iTRAQ results. ICAM1, TIMP1, SERPINC1 and ADIPOQ were upregulated in Uygur IgAN. Bioinformatic analysis revealed that the increase of ICAM1 and TIMP1 might be caused by IgAN, but the increase of SERPINC1 and ADIPOQ might be caused by proteinuria. SERPINC1 and ICAM1 were identified as the candidate biomarkers with excellent area-under-the-curve (AUC) values (0.84) for distinguishing Uygur IgAN from normal controls. CONCLUSIONS: Using urinary proteomic analysis, we identified several candidate biomarkers for IgAN in patients of Uygur ethnicity. These results will prove helpful for exploring the pathological mechanism of IgAN in patients of Uygur ethnicity and for developing better treatments for these patients.

[Nephrotic syndrome revealed by pulmonary embolism: about four cases]. / Embolie pulmonaire révélant un syndrome néphrotique : à propos de quatre cas.

Nephrotic syndrom is an association of proteinuria>3g/d or 50mg/kg/d, an hypoalbuminemia<30g/L and a hypoproteinemia<60g/L. Primary etiologies are minimal glomerular injury, focal segmental glomerulosclerosis and non membranous glomerulonephritis. Secondary etiologies are diabetes, high blood pressure and amyloidosis. We present four cases about nephrotic syndrome after thromboembolic disease. In every case, patients show a pulmonary embolism symptomatic of a nephrotic syndrom, whose diagnostic could be delayed up to six months after first pulmonary symptoms. This raised the problem of renal biopsy in these patients who need anticoagulation. In minimal change nephrosis, without hematuria, high blood pressure or renal dysfonction, a corticosteroid therapy test could be done assuming that is corticosensitive minimal glomerular injury. In every case, anticoagulation course must be completed and maintained in case of patent nephrotic syndrom with an albuminemia under 20g/L. In case of pulmonary embolism or deep vein thrombosis, idiopathic-looking, a nephrotic syndrome must be sought-after. The two diagnosis ways are the proteinuria on the urine dipstick and the hypoproteinemia on usual biology. The main mechanism is the coagulation factor leak, side effect of the nephrotic syndrom, notably because of the antithrombin III.

[Soluble fibrin is not excreted in urine and its plasma level is elevated in nephrotic syndrome].

Soluble fibrin (SF) is produced by activated blood coagulation reaction and is useful to diagnose thrombotic diseases. We measured plasma and urine SF levels in nephritic patients to assess the hypercoagulability state associated with the disease. Before they received anti-coagulation or anti-platelet therapies, 60 patients underwent measurement of plasma SF and D-dimer levels by Latex agglutination turbidimetric immnoassay (LA). Urinary SF levels were also measured by LA. Plasma and urinary thrombin antithrombin III complex (TAT) levels were measured by enzyme immunoassay (EIA). Plasma SF levels showed a good correlation with plasma TAT levels but only weak positive correlations were observed between plasma D-dimer and SF or TAT levels. Plasma SF and D-dimer levels were significantly higher in the Iatients with nephrotic-range hypoalbuminemia (< or =3 g/dL) than those without it. Contrarily there was no significant difference in plasma TAT levels between these two groups of patients. In almost all patients, urinary SF levels were under the detection limit. However, TAT was excreted into urine more frequently in patients showing the nephrotic range of hypoalbuminemia at 38.2% than in non-nephrotic patients at 8.0%. Thus, plasma SF levels more precisely indicate activated blood coagulation reaction than plasma TAT levels in nephrotic patients, probably because the plasma SF is not excreted into urine, while plasma TAT is.

Characterization of five marker levels of the hemostatic system and endothelial status in normotensive pregnancy and pre-eclampsia.

OBJECTIVES: Pre-eclampsia is associated with changes in the hemostatic system and endothelial status. Urinary 11-dehydrothromboxane B2/creatinine (11-DTXB2/Cr) is a marker for platelet activation and vascular constriction, thrombin-antithrombin complex (TAT) for thrombin formation, serum thrombomodulin (TM) for endothelial damage, and beta-thromboglobulin (beta-TG) and platelet factor 4 (PF-4) for platelet activation and releasing reaction. The present study attempted to evaluate these five markers in normotensive pregnancy and pre-eclampsia. METHODS: These five markers were simultaneously measured in urine and blood samples from 25 women who were not pregnant (group 1, controls), 31 women with normotensive pregnancy (group 2, second controls), 22 women with mild pre-eclampsia (group 3), and 21 women with severe pre-eclampsia (group 4). The average gestational age was 36 wk. RESULTS: The 11-DTXB2/Cr, TAT, and beta-TG levels were significantly higher (P < 0.01) in groups 2, 3, and 4 than in group 1. The TM and beta-TG levels were significantly higher (P < 0.05) in group 3 than in group 2. The TM, beta-TG, and PF-4 levels were increased significantly (P < 0.05-0.01) in group 4 compared to those in groups 1, 2, and 3. CONCLUSION: Platelet aggregation, vascular constriction, and thrombin formation (detected by 11-DTXB2/Cr and TAT) may be markedly enhanced even in group 2, but further enhancement may be relatively slight in groups 3 and 4. In contrast, endothelial damage (determined by TM) and platelet release of PF-4 may not increase significantly in group 2, but they may increase in group 4. Platelet-release of beta-TG may be enhanced in groups 2, 3, and 4. Endothelial damage and platelet-releasing reaction (detected by PF-4 and beta-TG) may be significantly more enhanced in group 4 than in group 3.

[The determination of the concentration of antithrombin III in the urine]. / Opredelenie kontsentratsii antitrombina III v moche.

The authors developed the special enzyme immunoassay technique for the detection of the urinary antitrombin III (AT-III) levels. Sensitivity of the method was 7.8 ng/ml. The study lasted for 2 hrs. The levels of AT-III were studied in the circadian human urine in health, in physiological and nephropathy-complicated pregnancy, as well as in patients with gastroduodenal ulcer-induced bleeding. There was a 34.1-fold increase in the urinary AT-III levels in pregnant females with Stages II-III nephropathy and a 17.3-fold increase in those who sustained the resection of the stomach, which could be explained by proteinuria and abnormal resorption of AT-III in the proximal tubules of the kidney.

Antithrombin III in children with various renal diseases.

Levels of antithrombin III (AT-III) activity and antigen in plasma and urine in children with renal diseases, and their correlation with the light microscopic findings of kidney tissue and the fluorescence of glomeruli, were investigated. AT-III activity in plasma was reduced slightly during the acute stage of acute glomerulonephritis and moderately in the relapse stage of nephrotic syndrome, whereas a small increase of AT-III antigen level in urine was noted in the acute stage of glomerulonephritis and considerably more was observed during the relapse stage of nephrotic syndrome. During the acute stage of glomerulonephritis or in some primary persistent glomerulonephritis (IgA nephritis, non-IgA nephritis), Henoch-Schönlein purpura nephritis and nephrotic syndrome, localization of small amounts of AT-III was noted on the capillary walls of glomeruli. These findings were in parallel with the proliferative changes of glomeruli. However, the AT-III localization did not change in parallel with the light microscopic findings or degree of the fluorescence of the fibrinogen/fibrin-related antigen. It was thought that the existence of AT-III antigen on the capillary walls of the glomeruli might be associated with the inhibition of excessive fibrin formation by AT-III.

Plasma and urinary heparin cofactor II levels in patients with nephrotic syndrome.

Heparin cofactor II (HC II) levels were measured by electroimmunoassay in plasmas and urines from 68 patients with nephrotic syndrome. In addition, antithrombin III (AT III) and protein C (PC) activities and antigens were measured also in the same group of patients. Seven of these patients had histories of thrombosis. Plasma HC II levels (mean +/- SD 105 +/- 43) were not different from levels in healthy subjects (94 +/- 17). Only 5 patients had low plasma levels of HC II. None of the patients with thrombosis had low HC II levels. Even though measurable amounts of HC II were found in 25 urines from 50 patients. There was a relationship in the urinary excretion between HC II and AT III and their urinary clearances were quite similar. However, no correlation was found between plasma HC II and AT III levels, and levels of AT III activity and antigen were significantly lower than in healthy subjects. Three patients with histories of thrombosis had low AT III levels. Most patients (including those with thrombosis histories) had high plasma PC levels and increased urinary loss. It is suggested that HC II does not play an important role in the pathogenesis of thrombosis in nephrotic syndrome.

Antithrombin III loss in patients with nephrotic syndrome or receiving continuous ambulatory peritoneal dialysis. Evidence of inactive antithrombin III in urine of patients with nephrotic syndrome.

Antithrombin III (AT III) was measured as antigen (Ag) and as heparin cofactor (HC) in plasma and urine or dialysate from nine patients with nephrotic syndrome and nine patients receiving continuous ambulatory peritoneal dialysis (CAPD), respectively. Crossed immunoelectrophoresis on heparin-agarose (H-CIE) and crossed immunoelectrofocusing (CIEF) runs were carried out on plasma and urine or dialysate samples. AT III plasma levels of the patients receiving CAPD were in the normal range, whereas levels in the patients with nephrotic syndrome showed a significant reduction. Nevertheless the AT III Ag daily loss was the same in both patient groups, so that an additional AT III loss caused by renal metabolism was suggested in patients with nephrotic syndrome. No alteration in the isoantithrombin plasma distribution was found in any patient. The AT III recovered in urine was almost all inactive, as demonstrated by the quantitative assays and by the H-CIE runs; on the contrary, the findings obtained by functional assays, H-CIE, and CIEF runs on dialysate samples failed to demonstrate any major alteration in the AT III molecule. In urine the AT III CIEF pattern displayed a more acid distribution (pH 4.9 to 4.5) in respect to the plasma AT III (pH 5.2 to 4.6); this pattern was suggested to be related to the renal AT III functional inactivation, whose exact mechanism remains to be clarified.

Antithrombin III metabolism in two patients with a nephrotic syndrome caused by minimal chain nephritis and primary amyloidosis.

The metabolism and urinary excretion of 125I antithrombin III (AT III) was investigated in 2 patients with a nephrotic syndrome caused by minimal chain nephritis and primary amyloidosis, and acquired deficiency of AT III. Increased AT III catabolism was observed in both patients, even after correction for urinary protein loss. Increased AT III catabolism was due to increased influx from the extra- to the intravascular compartment in 1 patient, and to an increased fractional catabolic rate in the other patient who developed later a pulmonary embolism. Analysis of urine samples revealed biologically inactive whole AT III molecules and biologically as well as antigenically inactive fragments, respectively, whereas daily plasma gel filtration showed intact radioactive AT III. These observations reject the hypothesis that AT III deficiency in nephrotic patients is only due to urinary loss of AT III.

Molecular analysis of urinary AT III related antigen in liver cirrhosis.

Urinary antithrombin III (AT III) related antigen was analyzed by SDS-polyacrylamide gel electrophoresis and Western blotting, and the nitrocellulose membrane was scanned with a 2-wavelength TLC scanner. The urinary AT III related antigen was found to be located in three different molecular weight regions: the AT III region, and molecular weight regions higher and lower than that of AT III. The ratio of the higher molecular weight region to the AT III region divided by the urinary creatinine, was taken as an "index" and was analyzed in liver cirrhosis patients as well as in normal controls. The "index" in liver cirrhosis was higher than that in the controls. Further, the "index" revealed a significant proportional correlation with the total bilirubin and direct bilirubin, and also a significant inversely proportional correlation with the plasma AT III, suggesting that the "index" tends to become higher as liver function decreases. The pathophysiological significance of the "index" is briefly discussed.

High plasma levels of protein C activity and antigen in the nephrotic syndrome.

Low plasma levels of antithrombin III due to excessive urinary loss are thought to be the cause of thrombotic complications in patients with the nephrotic syndrome. To see whether protein C (PC), another antithrombotic protein, is also reduced in plasma by the same mechanism, plasma and urinary protein C were determined in 24 patients with nephrotic syndrome and no thrombotic complication, and compared to plasma and urinary antithrombin III. Twenty patients (83%) had high plasma levels of protein C activity (mean +/- SD 157 +/- 41 U/dl) and antigen (158 +/- 41). Even though measurable amounts of PC antigen were found in the urines of all but two patients the urinary loss of protein C relative to its plasma concentration was about 40 times lower than that of antithrombin III. High protein C might help to counteract hypercoagulability in nephrotic syndrome.

Antithrombin III (AT III) and fibrinogen levels in nephrotic syndrome in children.

Plasma antithrombin III (AT III) and fibrinogen were measured in 25 Saudi children with nephrotic syndrome during both relapse and remission. During relapse the mean AT III level was 46.6% (range 7-84%) and mean fibrinogen was 992 mg/dl (range 413-1,433), while during remission, AT III levels increased remarkably to a mean value of 120.6% (range 81-160) and plasma fibrinogen dropped to a mean level of 431 mg/dl (range 230-693). In 10 of these patients AT III was measured simultaneously in urine. During relapse urine AT III levels were of the same magnitude as plasma AT III, while during remission no AT III was detected in urine. These findings confirm the hypercoagulable state during the relapse of nephrotic syndrome and the quick recovery during remission. None of our patients showed any clinical evidence of thromboembolism. Loss of AT III in urine during relapse and/or its consumption is the probable cause of low AT III during relapse while excessive production of AT III by liver probably accounts for the high levels in remission.

Acquired deficiency and urinary excretion of antithrombin III in nephrotic syndrome.

The published data concerning changes of antithrombin III (ATIII) in nephrotic syndrome (NS) are contradictory. While increased ATIII activity has been reported by some investigators, decreased concentration has been shown by others and normal values by yet another group of authors. We determined plasma and urine concentrations of ATIII in a group of 20 patients with NS using an immunologic assay. In addition, plasma ATIII activity was determined. The results were compared with those obtained in a group of normal volunteers. Plasma concentration and activity of ATIII were both greatly reduced in the patients with NS. In addition, substantial quantities of ATIII were recovered in the urine of all tested patients. The present study, therefore, substantiates the low plasma concentrations of ATIII and its urinary losses in NS. In addition, a parallel reduction in plasma ATIII activity is demonstrated providing functional evidence of acquired ATIII deficiency in this condition.

[Plasma and urinary antithrombin III in the nephrotic syndrome in adults]. / Antithrombine III plasmatique et urinaire au cours des syndromes néphrotiques de l'adulte.

The occurrence of thromboembolism in nephrotic syndrome has been recently correlated with acquired antithrombin III (AT III) deficiency (and this raised the question of the prevention and treatment of thromboembolism with heparin). We studied AT III levels in plasma and urine in 39 adults with nephrotic syndrome. Three patients have had thromboembolic manifestations (before treatment with heparin). Their albuminemia was less than 18 g/l, their plasmatic AT III levels were normal and one had an elevated urine AT III level. Plasmatic AT III levels and albuminemia were positively correlated (r = 0.34; p less than 0.05) but AT III levels remained in the normal range being moderately diminished in only 3 patients never less than 70 p. 100. There was no correlation between plasmatic AT III level and proteinuria or urinary AT III levels. We conclude that the risk of thromboembolism in adults with nephrotic syndrome is not correlated with plasmatic AT III levels. This suggests that heparin therapy would be effective in preventing thromboembolism in this disorder. Indeed, no such episodes were seen in our patients under heparin.

Antithrombin III and fibrinogen degradation product (fragment E) in diabetic nephropathy.

Plasma antithrombin III (AtIII), serum fragment E (FgE) and urine AtIII and FgE were measured in 25 diabetic patients with proteinuria above 1 g per day and compared to that in 25 patients with non-diabetic nephropathy, matched for the degree of proteinuria. Plasma AtIII concentrations were normal in both groups but FgE concentrations were increased. The level of plasma AtIII was directly related to HbA1 concentrations in the diabetics. For the same degree of proteinuria, the diabetic patients lost more AtIII and FgE in the urine. Urine AtIII was found to be mostly bound to activated procoagulants. Both urine AtIII and urine FgE correlated inversely with creatinine clearance. It was concluded that intraglomerular thrombosis probably contributes to the deteriorating renal function in diabetic nephropathy and is reflected in the concentrations of urine AtIII and FgE.

Plasminogen and antithrombin III deficiencies in the childhood nephrotic syndrome associated with plasminogenuria and antithrombinuria.

Three of four patients with the childhood nephrotic syndrome were found to have low plasma plasminogen concentrations; all four had low plasma antithrombin III concentrations. In the two patients who were tested, urinary concentrations of these proteins exceeded the plasma concentrations. As the urinary losses of plasminogen and antithrombin III decreased over the course of illness, the plasma concentrations of antithrombin III and plasminogen rose. One patient had multiple thromboembolic episodes. We conclude the deficiencies of antithrombin III and plasminogen, probably secondary to urinary excretion of these proteins, may contribute to the thrombotic diathesis associated with nephrotic syndrome.

Automated two-stage assay for determination of antithrombin III with a centrifugal analyzer.

The thrombin-inactivating alpha 2-globulin, antithrombin III (At-III), was measured in plasma and urine with a chromogenic tripeptide substrate, using a centrifugal analyzer. Plasma At-III was subnormal in liver disease. In acute myocardial infarction a mean At-III of approximately 120% of normal was found. At-III in persons who developed deep-vein thrombosis decreased significantly (p less than 0.05) between the day of admission and the 3rd day after admission to hospital. Urine from normals did not contain detectable At-III. With increasing urinary albumin increasing concentration of At-III was found.