vWF及GPIb在慢性肾脏疾病中变化及作用

目的研究假性血管血友病因子（vWF）及血小板膜糖蛋白Ib（GPIb）在慢性肾脏疾病（CKD）不同阶段的变化及意义。方法87例患者按病因及CKD不同阶段分为5组,A组：CKD1期,肾小球肾炎组,17例;B组：CKD1期,原发性肾病综合征组,14例;C组：CKD1期,继发性肾病组,18例;D组：CKD2～4期,慢性肾衰组,18例;E组：CKD5期,慢性肾衰透析组,20例。酶联免疫吸附检测法测定GPIb、双抗体夹心固相酶免疫测定血浆vWF。结果vWF、GPIb在A、B、C、D、E组均明显增高,以B、C组尤为突出;与凝血状况正相关。结论vWF水平可同时反应内皮细胞受损及凝血状态,在肾小球疾病发展中可能有重要意义。     

The structure of the von Willebrand factor is not altered in patients with colorectal carcinoma

Aim Elevated levels of von Willebrand factor (VWF) are often observed in many diseases including colorectal cancer, but this finding is not definite. The aim of our study was to examine the change in VWF multimer distribution in patients with colorectal cancer. Method We randomly selected nine patients from each of the four Union for International Cancer Control (UICC) stages of colon cancer. VWF antigen (VWF:Ag), VWF‐cleaving protease ADAMTS‐13 level and factor VIII activity (FVIII:C) were determined. The multimer distribution of VWF was visualized using electrophoretic multimer analysis. Results The VWF multimer structure was normal with no difference between the four UICC stages. There was no significant increase in VWF:Ag and FVIII:C levels in the more advanced UICC stages. There was no significant difference in the ADAMTS‐13 level according to the UICC stage. Conclusion There was no change in the VWF multimer distribution to indicate acquired von Willebrand disease.     

Development of a Severe von Willebrand Factor/ADAMTS13 Dysbalance During Orthotopic Liver Transplantation

Patients with liver disease show profound changes in their hemostatic system, which may further change during liver transplantation. We previously demonstrated that highly elevated levels of the platelet adhesive protein von Willebrand factor (VWF) in patients with cirrhosis lead to an increased VWF-dependent platelet deposition under flow as compared to healthy controls. In this study we examined VWF parameters during the course of liver transplantation. We collected serial plasma samples from 20 patients undergoing liver transplantation in which we determined plasma levels of VWF and the VWF-cleaving protease ADAMTS13. Furthermore, we performed functional tests of VWF-dependent platelet adhesion. We found persistently elevated levels of VWF during and after liver transplantation. The capacity of VWF to interact with platelets normalized during the course of transplantation, and flow-mediated VWF-dependent platelet adhesion remained at levels far exceeding those observed in healthy individuals during and after transplantation. Plasma levels of ADAMTS13 dropped during transplantation, and in four patients levels below 10% of normal were observed after reperfusion. We observed the development of a hyperreactive primary hemostatic system, as evidenced by high levels of fully functional VWF and a temporary ADAMTS13 deficiency, during liver transplantation, and speculate that these changes contribute to postoperative thrombotic complications.     

Correlation between von Willebrand factor levels and early graft function in clinical liver transplantation

Cold preservation/reperfusion leads to sinusoidal endothelial cell (SEC) activation and damage in nearly every liver transplantation; the extent of these changes influences early graft function. Upon reperfusion, activated SEC show increased expression of adhesion molecules, including von Willebrand factor (vWF) which is released into the circulation. This study was designed to evaluate the levels of vWF measured in the caval effluent and correlate these findings with known markers of SEC damage and early graft function. Data were obtained from 35 patients undergoing orthotopic liver transplantation (LTx). Two samples were taken from each patient for measurement of vWF: a) from the portal vein immediately prior to reperfusion; and b) from the first 50 ml of the caval effluent. Commercial assays were used to measure vWF, as well as hyaluronic acid (HA), thrombomodulin (TM), IL-1β, IL-6, IL-8 and TNF-α. Patients were divided into two groups based on early graft function. Poor early graft function (PEGF) was defined as a peak aspartate transaminase (AST) or alanine transaminase (ALT) level> 2500 U/L during the first three postoperative days (POD) and a prothrombin time (PT)> 16 s on POD 2 (n=8). The remaining 27 patients had good early graft function (GEGF). In patients with GEGF, vWF levels dropped significantly between the two time points. This change was not observed in those with PEGF. A positive linear correlation was observed in the PEGF group between vWF and HA and IL-6. The different pattern of change in vWF between the two groups, as well as the positive correlation between HA, IL-6 and vWF in PEGF, suggest that vWF may be a useful marker of early graft function.     

Disordered regulation of coagulation and platelet activation in xenotransplantation

Rejection of xenografts is associated with vascular-based inflammation, thrombocytopenia and the consumption of coagulation factors that may evolve into disseminated intravascular coagulation (DIC). Similarly, bone marrow-derived cellular xenotransplantation procedures are associated with endothelial cell activation and thrombotic microangiopathic injury. These complications generally develop despite the best available measures for depletion of xenoreactive natural antibody, inhibition of complement activation and suppression of T- and B-cell mediated immune responses. The mechanisms underlying the DIC and thrombotic microangiopathy associated with xenotransplantation are unclear. A proposed primary biological dysfunction of xenografts with respect to regulation of clotting could amplify vascular injury, promote immunological responses and independently contribute to graft failure. Disordered thromboregulation could have deleterious effects, comparable to unregulated complement activation, in the pathogenesis of xenograft rejection and may therefore represent a substantive barrier to xenotransplantation.     

Severe thrombotic and bleeding complications in a baby with heterozygous factor V Leiden and acquired von Willebrand disease on ECMO

We aim to present the case of a 5-week-old girl with severe respiratory failure placed on veno-venous extracorporeal membrane oxygenation (ECMO) that was then switched to veno-arterial ECMO. She required up to 60 units/kg/hr of heparin to keep her heparin level within the target range at .3-.7 units/mL. During the ECMO course, substantial thrombus formation was observed within the venous site of the ECMO cannula, which led to two circuit changes on ECMO day 9 and day 20. On ECMO day 15, she was noticed to have purpuric lesions on her chest and her right hand with no obvious arterial or venous clot detected by Doppler ultrasound. She was also noted to have remarkable hemolysis as the plasma free hemoglobin levels were substantially elevated up to 700 mg/dL. She was noted to have continuous oozing from the catheter insertion sites despite adequate underlying coagulation status. Her subsequent platelet function analysis, the thromboelastography, and thromboelastography platelet mapping suggested substantial platelet dysfunction. Her von Willebrand panel revealed absence of high molecular weight multimers. Further coagulation workup was prompted which revealed heterozygosity for factor V Leiden. The patient developed severe pulmonary hemorrhages and ECMO was discontinued on day 40.     

血管性血友病因子对结直肠癌细胞生物学特性的影响

目的 探讨血管性血友病因子（vWF）对人结直肠癌细胞生长、黏附和迁移能力的影响.方法 体外培养人结直肠癌细胞株SW480,采用免疫细胞化学方法检测SW480细胞中vWF的表达情况.用vWF抗体对其进行处理,采用倒置显微镜观察细胞形态学变化;MTT法检测细胞增殖活性和对细胞外基质成分--Ⅳ型胶原黏附能力的变化;Transwell法检测细胞迁移能力的改变.结果 SW480细胞能够表达vWF,染色部位主要位于细胞核,细胞质亦有轻微表达.vWF抗体能够显著抑制SW480细胞的生长,该抑制作用呈剂量及时间依赖性（P〈0.05）;20 ms/L vWF抗体处理48 h后,SW480细胞的黏附力明显下降（P〈0.05）;迁移能力明显减弱[穿膜细胞数（54.60±11.01）比（97.27±10.01）,P〈0.01].结论 人结直肠癌细胞能够表达vWF;vWF对人结直肠细胞的生长、黏附、迁移过程中起重要促进作用.     

Recipient levels and function of von Willebrand factor prior to liver transplantation and its consumption in the course of grafting correlate with hepatocellular damage and outcome.

Von Willebrand factor (vWF) is a major platelet adhesion molecule at sites of vascular injury, such as observed in ischemia/reperfusion injury following orthotopic liver transplantation (OLT). Thirty-three OLT patients were divided into groups with elevated or low markers of hepatocellular damage (high and low-HD). Whole-blood aggregometry was performed to evaluate platelet function. Multimeric analysis was utilized to evaluate functional vWF levels in the course of OLT. Donor and recipient demographics were comparable among groups. Low-HD patients demonstrated better preserved coagulation parameters on POD 1-6 if contrasted to high-HD patients. One year graft survival for the high-HD group was lower than low-HD patients (P = 0.037). Preoperative vWF-dependent platelet aggregation and functional vWF plasma levels correlated directly with alanine transaminase levels early after OLT as did the decrease of functional vWF to reperfusion. In summary, these data suggest that vWF may serve as a significant mediator of platelet recruitment and hepatocellular injury in the graft following reperfusion.     

Von Willebrand factor and factor XIII in children with Henoch-Schonlein purpura

Levels of von Willebrand factor antigen (vWf: Ag) and factor XIII activity (F XIII) were studied in relation to the severity of clinical symptoms (scored from 0 to 3) and to immunological parameters [IgA, C3, C4, and circulating immune complexes (CIC) in 16 children (7 males, 9 females, aged 3–11 years) with Henoch-Schonlein purpura (HSP) at presentation. vWf: Ag was increased in 7 patients, F XIII activity was decreased in 6. In all children we found high levels of IgA, while C3 and C4 levels were normal; CIC were elevated in 11. vWf: Ag correlated with clinical score and with IgA and CIC, probably as a result of immune-mediated endothelial cell damage. The haemostatic alterations observed in HSP are important for understanding the pathophysiology of the disease.     

血管性血友病因子对冠心病发生影响的研究进展

von Willebrand因子又称血管性血友病因子,通过特异的血小板膜受体（糖蛋白Ιb-IX复合物）介导血小板与内皮下层的黏附,是一个反应内皮损伤的标志物,其增高有利于血小板的黏附。vWF与冠心病的发生相关,是反映内皮细胞受损的可靠指标之一。本研究通过对vWF生物学特点、生理功能、作用机理及对冠心病发生影响的相关论文的研究整理,为临床探讨冠心病影响因素及治疗提供参考依据。     

Antibodies to human adhesion molecules and von Willebrand factor: In vitro cross-species reactivity in the xenotransplantation setting

Abstract: Endothelial cell activation is thought to play an important role in xenograft rejection through cell retraction and expression of pro-coagulant and pro-inflammatory factors. Identification of antibodies recognizing porcine endothelial molecules would be useful to study and manipulate the inflammatory response to a xenograft. The aim of this study was to investigate the cross-reactivity of antibodies directed against human adhesion molecules and von Willebrand factor (vWF). Binding of monoclonal antibodies (mAbs) directed against human CD31, CD44, CD49, CD54, CD62E, CD102, and CD106 was evaluated on resting and activated endothelial cells from human and pig by flow cytometry. Among 30 antibodies tested, 4 were shown to react with pig cells. Two of them, directed against human CD62E (E-selectin) and rabbit CD 106 (VCAM-1) reacted strongly with activated and/or resting pig cells, whereas two others, directed to human CD31 (PECAM) and CD44 (H-CAM), bound weakly to pig cells. In addition, we analyzed the cross-reactivity of five polyclonal or monoclonal antibodies to human or pig vWF with human, baboon, rhesus, pig, and rat vWF. Binding of antibodies was tested by ELISA by using platelet lysates as source of vWF from the different species. Four anti-human or porcine vWF antibodies exhibited a broad reactivity with vWF from all species, whereas one anti-human vWF antibody was specific for primate vWF. In this study, we identified a small number of cross-reacting antibodies that may prove useful to study in vitro and in vivo xenogeneic responses. However, the weak antibody cross-reactivity observed with most porcine molecules points out the necessity of producing species-specific antibodies to study the immune response to xenografts or for use as specific immunosuppressive therapeutic reagents.     

The effect of vibration on back discomfort and serum levels of von Willebrand factor antigen: A preliminary communication

Summary The von Willebrand factor (vWf) is a complex protein whose release is a marker for endothelial damage; serum levels of its antigen (vWFAg) can be used as a marker for such changes. We measured the levels of back discomfort and vWFAg in 11 subjects following 25-min periods of (1) lying down, (2) sitting upright, (3) vibrating whilst sitting and (4) sitting upright. Back discomfort appeared and vWf levels were significantly increased following sitting upright, compared with lying flat, and increased further following vibration. They fell thereafter with a period of sitting still upright. These results demonstrate that vibration has a significant effect in increasing back discomfort and the serum levels of vWFAg, and it is possible that vibration may induce vascular damage within the spine.     

低温体外循环血中血管性假血友病因子浓度及循环内皮细胞的观察

目的观察先天性心脏病患者体外循环围手术期血管性假血友病因子（ｖｏｎＷｉｌｅｂｒａｎｄｆａｃｔｏｒ,ｖＷＦ）及血循环内皮细胞（ｃｉｒｃｕｌａｔｉｎｇｅｎｄｏｔｈｅｌｉａｌｃｅｌｓ,ＣＥＣ）数的动态变化过程,探讨低温体外循环对血管内皮细胞的影响。方法于肝素化后体外循环前、转流３０分钟、开放主动脉５分钟、停机、停机后４小时和术后第１天晨用酶联免疫法测定２０例先天性心脏病患者血浆中ｖＷＦ浓度,同时用Ｐｅｒｃｏｌ密度梯度离心法对患者血中ＣＥＣ进行计数和形态学观察。结果转流３０分钟、开放主动脉５分钟、停机、停体外循环后４小时、术后第１天晨ｖＷＦ水平和ＣＥＣ数较体外循环前显著升高（Ｐ＜０．０５）。结论体外循环可导致血管内皮细胞激活或损伤     

Establishing a Method for In Vitro Investigation of Mechanical Parameters Causing Acquired von Willebrand Syndrome in Ventricular Assist Devices

Acquired von Willebrand Syndrome (AvWS) is known as a frequent bleeding complication in patients on ventricular assist device (VAD) support. Clinicians demand that the requirements for VADs with regard to hemocompatibility should also include low susceptibility for AvWS. Clinical AvWS diagnosis is known to be a complex, high‐price, and time‐consuming analysis. This article investigates an easy‐to‐handle, time‐efficient, and inexpensive method for comparative AvWS investigations in vitro. Von Willebrand Factor activity level (vWF : Ac) and von Willebrand Factor antigen level (vWF : Ag) were chosen from the complete set of clinically established parameters. Blood plasma (human and porcine) was exposed to an inhomogeneous shear field in a shear‐inducing test set up for up to 4 h. Plasma samples were drawn after different load periods and analyzed for vWF : Ac and vWF : Ag. vWF multimer analysis of selected samples were used as reference for determination of high molecular weight multimer (HMWM) loss. AvWS was detected after 20 min of shear load via vWF : Ac/vWF : Ag ratio and multimer analysis. A good correlation between the vWF : Ac/vWF : Ag ratio and HMWM loss (multimer analysis) was found for human plasma. AvWS characteristics of human and porcine plasma for analyzed samples were comparable. A correlation between vWF : Ac/vWF : Ag ratio and HMWM in porcine plasma could not be found. Results gained in this study indicate that vWF : Ac/vWF : Ag ratio is sensitive enough for comparative AvWS investigations in vitro with human blood. The applicability of the method suggested in this article for AvWS characterization in porcine blood needs to be investigated in further studies. The selection of analysis kits promises a less cost‐ and labor‐intensive, time‐consuming, and complex method for comparative AvWS investigations in vitro compared with AvWS diagnosis in patients.     

Prognostic implications of retinopathy and a high plasma von Willebrand factor concentration in type 2 diabetic subjects with microalbuminuria.

BACKGROUND: Microalbuminuria in subjects with type 2 diabetes may be heterogeneous with respect to clinical features, renal histology, and prognosis. There may be at least two types of microalbuminuria in diabetes, namely with and without generalized endothelial dysfunction. We investigated whether, among microalbuminuric subjects with type 2 diabetes, the presence of generalized endothelial dysfunction, as indicated by the presence of retinopathy or a high plasma von Willebrand factor (vWf) level, has prognostic implications. METHODS: In 173 type 2 diabetic subjects of a population-based cohort, we assessed the urinary albumin-to-creatinine ratio, the plasma vWf level, and the presence of retinopathy. The main outcome was cardiovascular mortality. RESULTS: The absolute difference in 7 years' cardiovascular mortality between microalbuminuric (albumin-to-creatinine ratio 2.0-30.0 mg/mmol) and normoalbuminuric subjects was higher in the presence as compared to the absence of retinopathy (55.6 vs 11.1%). The age- and sex-adjusted relative risk (95% confidence interval) of cardiovascular mortality, as compared to normoalbuminuric subjects without retinopathy, was 1.1 (0.1-9.2) for normoalbuminuric subjects with retinopathy, 1.8 (0.5-6.7) for microalbuminuric subjects without retinopathy, and 9.8 (3.1-30.9) for microalbuminuric subjects with retinopathy. The absolute difference in risk of 7 years' cardiovascular mortality between microalbuminuric and normoalbuminuric subjects was higher in the presence as compared to the absence of a high (>1.89 IU/ml) vWf level (49.8 vs 16.4%). The age- and sex-adjusted relative risk of cardiovascular mortality, as compared to normoalbuminuric subjects without a high vWf level, was 1.5 (0.4-5.5) for normoalbuminuric subjects with a high vWf level, 2.6 (0.7-9.6) for microalbuminuric subjects without a high vWf level, and 12.0 (2.9-49.5) for microalbuminuric subjects with a high vWf level. These differences in risk of cardiovascular mortality did not change materially after further adjustment for known duration of diabetes, hypertension, creatinine clearance, level of glycated haemoglobin and high-density lipoprotein cholesterol, and presence of cardiovascular disease. Analysis of all-cause instead of cardiovascular mortality showed a similar difference in risk of mortality between microalbuminuric subjects with or without retinopathy or a high vWf level. CONCLUSIONS: Among type 2 diabetic subjects with microalbuminuria, the presence of retinopathy or a high plasma vWf level affects the risk of cardiovascular death. Although larger studies are necessary, these findings support the concept that microalbuminuria in type 2 diabetes can occur in the absence or the presence of generalized endothelial dysfunction, and that the latter is a much more 'malignant' condition than the former.     

Elevation of serum von Willebrand factor and anti-endothelial cell antibodies in patients with immunoglobulin A nephropathy are associated with intrarenal arterial lesions

Aim: Recent studies suggest that intrarenal arterial lesions are frequently observed in patients with immunoglobulin A nephropathy (IgAN). However, the mechanisms of the injury have not been elucidated. The level of serum von Willebrand factor (vWF) and the prevalence of anti-endothelial cell antibodies (AECA) were investigated in patients with IgAN with different intrarenal arterial lesions. Methods: Sera from 28 patients with mild intrarenal arterial lesions (group 1) and 36 patients with severe intrarenal arterial lesions (group 2) were collected. Sera from 20 patients with idiopathic membranous nephropathy (group 3) and 50 healthy volunteers were also obtained as disease and normal controls, respectively. Serum vWF and AECA of both IgG and IgA isotype were detected. Results: In comparison with normal controls, serum vWF was significantly higher in group 2 and group 3. Serum vWF was also significantly higher in group 2 than in group 1. Both IgG-AECA and IgA-AECA could be detected in three groups of patients. The prevalence of anti-87 kD IgG-AECA was greatest in patients in group 2. IgAN patients, especially those in group 2 with IgG-AECA or anti-87 kD IgG-AECA, had significantly higher serum creatinine and lower creatinine clearance than those without. No significant difference could be found for IgA-AECA. The level of serum vWF was higher in IgAN patients with IgG-AECA than that in patients without. Conclusion: Intrarenal arterial lesions are associated with endothelial cell damage in IgAN, and vWF is a useful serological biomarker of severe intrarenal arterial lesions. AECA, especially IgG-AECA, may play an important role in the pathogenesis of intrarenal arterial damage in IgAN.