ADAMTS13 and von Willebrand factor assessment before and after kidney transplantation

Emerging Targets for Modulation of Immune Response and Inflammation in Stroke

The inflammatory and immunological responses play a significant role after stroke. The innate immune activation stimulated by microglia during stroke results in the migration of macrophages and lymphocytes into the brain and are responsible for tissue damage. The immune response and inflammation following stroke have no defined targets, and the intricacies of the immunological and inflammatory processes are only partially understood. Innate immune cells enter the brain and meninges during the acute phase, which can cause ischemia damage. Activation of systemic immunity is caused by danger signals sent into the bloodstream by injured brain cells, which is followed by a significant immunodepression that encourages life-threatening infections. Neuropsychiatric sequelae, a major source of post-stroke morbidity, may be induced by an adaptive immune response that is initiated by antigen presentation during the chronic period and is directed against the brain. Thus, the current review discusses the role of immune response and inflammation in stroke pathogenesis, their role in the progression of injury during the stroke, and the emerging targets for the modulation of the mechanism of immune response and inflammation that may have possible therapeutic benefits against stroke.

Endothelial Markers: Thrombomodulin and Von Willebrand Factor and Risk of Kidney Thrombosis After Transplantation

OBJECTIVE

Endothelial disturbance is well known as one of the causes of thrombosis. This study measured von Willebrand factor (vWF) and soluble thrombomodulin (sTM) in renal vein blood to evaluate for the risk of thrombosis after kidney transplantation.

METHODS

A cross-sectional study that included 61 consecutive recipients of kidney transplant. The sTM and activity of vWF were evaluated in blood of the renal vein at the time of reperfusion.

RESULTS

The renal vein blood had higher values of vWF activity and sTM concentration than the peripheral blood. In the first minutes of reperfusion, the concentration of thrombomodulin was the highest but activity of vWF was the lowest. As the reperfusion continued, thrombomodulin gradually decreased, but vWF increased. The strong correlations of TMs and vWF with warm ischemia were observed (r = 0.5577 and r = 0.3429, respectively). Thrombosis was found in about 10% of all recipients. However, other complications, such as delayed graft function or ureter necrosis, were associated with high values of vWF and sTM. They were correlated with increased sTM concentration and activity of vWF (P < .006 and P < .05, respectively). This was confirmed by analysis of the receiver operator characteristic curve. The area under the curve values for TMs and vWF were 0.762 and 0.602, respectively (P < .0001 and P < .015, respectively). The cutoff points for sTM and vWF were 14.89 ng/mL and 129.89%, respectively. Positive prediction value sTM and vWF were 76% and 66% and negative prediction value 69% and 59%, respectively.

CONCLUSIONS

The endothelium of a transplanted kidney could be involved in the pathogenesis of renal thrombosis. Endothelial protection during harvesting can greatly contribute to the improvement of transplantation outcomes. The renal pool of sTM and vWF could be a useful marker of the risk of renal thrombosis.

Hemostatic Parameters according to Renal Function and Time after Transplantation in Brazilian Renal Transplanted Patients

Kidney transplantation is the key for patients with end-stage renal disease, improving quality of life and longer survival. However, kidney transplant triggers an intense inflammatory response and alters the hemostatic system, but the pathophysiological mechanisms of these changes are not completely understood. The aim of this cross-sectional cohort study was to investigate hemostatic biomarkers in Brazilian renal transplanted patients according to renal function and time after transplantation. A total of 159 renal transplanted patients were enrolled and D-Dimer (D-Di), Thrombomodulin (TM), von Willebrand Factor (VWF), and ADAMTS13 plasma levels were assessed by ELISA. An increase of D-Di was observed in patients with higher levels of creatinine. ADAMTS13 levels were associated with creatinine plasma levels and D-Di levels with Glomerular Filtration Rate. These results suggested that D-Di and ADAMTS13 can be promising markers to estimate renal function. ADAMTS13 should be investigated throughout the posttransplant time to clarify the participation of this enzyme in glomerular filtration and acceptance or rejection of the graft in Brazilian transplanted patients.

ADAMTS13 and Von Willebrand factor in patients undergoing hemodialysis

Hemodialysis (HD) is associated with increasing thrombotic trend. Vascular access thrombosis (VAT) increases morbidity in HD patients. The aim of this study was to evaluate ADAMTS13 and VWF plasma levels from patients undergoing HD as putative biomarkers of the hypercoagulability state, as well the association between these markers and VAT occurrence. This study included 195 patients on HD for more than 6 months. HD patients were allocated into two groups according to the occurrence or not of previous episode of VAT; HD with VAT (N = 46) and HD without VAT (N = 149). ADAMTS13 and VWF were performed by ELISA. There was no significant difference between HD patients with and without VAT for ADAMTS13 and VWF levels. However, VWF levels were higher (P < 0.001) and ADAMTS13 were lower (P < 0.001) in HD patients, comparing to the control group composed by healthy subjects without kidney disease, age and sex-matched (N = 80). Taken together our data suggest a potential role of the kidneys function compromised on ADAMTS13 synthesis or metabolism, regardless other known sources of ADAMTS13. The imbalance between ADAMTS13 and VWF levels does not explain the development of VAT in HD patients by itself, although it should contribute for the hypercoagulability state. Therefore, additional studies to identify other risk factors are warranted and essential for better management of HD patients.

Relationship between ABO blood groups and von Willebrand factor, ADAMTS13 and factor VIII in patients undergoing hemodialysis

Several studies have demonstrated that non-O blood groups subjects present an increased VTE risk as compared to those carrying O blood group. The aim of this study was to investigate the ABO blood groups influence on factor VIII (FVIII) activity, von Willebrand factor (VWF), and ADAMTS13 plasma levels in patients undergoing hemodialysis (HD). Patients undergoing HD (N=195) and 80 healthy subjects (control group) were eligible for this cross-sectional study. The ABO blood group phenotyping was performed by the reverse technique. FVIII activity was measured through coagulometric method, and VWF and ADAMTS13 antigens were assessed by ELISA. FVIII activity and VWF levels were significantly higher and ADAMTS13 levels was decreased in HD patients, as compared to healthy subjects (P < 0.001, in three cases). HD patients carrying non-O blood groups showed a significant increase in FVIII activity (P = 0.001) and VWF levels (P < 0.001) when compared to carriers of O blood group. However, no significant difference was observed in ADAMTS13 levels (P = 0.767). In the control group, increased in FVIII activity (P = 0.001) and VWF levels (P = 0.002) and decreased in ADAMTS13 levels (P = 0.005) were observed in subjects carrying non-O blood groups as compared to carriers of O blood group.Our data confirmed that ABO blood group is an important risk factor for increased procoagulant factors in plasma, as FVIII and VWF. Admitting the possible role of kidneys in ADAMTS13 synthesis or on its metabolism, HD patients were not able to increase ADAMTS13 levels in order to compensate the increase of VWF levels mediated by ABO blood groups. Considering that non-O blood groups constitute a risk factor for thrombosis, it is reasonable to admit that A, B and AB HD patients need a careful and continuous follow-up in order to minimize thrombotic events.