Outcome of kidney transplantation in patients with inherited thrombophilia: data of a prospective study

Is there a procoagulant state long-term after lung transplantation? A prospective study

BACKGROUND

Venous thromboembolism (VTE) is a major complication after lung transplantation (LT). However, its pathophysiology remains unknown, and coagulation profiles have yet to be described.

OBJECTIVE

The aim of this study was to longitudinally assess coagulation status after LT.

METHODS

We performed a prospective study and described the coagulation profiles of 48 patients at 5 different time-points: before LT and at 24-72 h, 2 weeks, 4 months, and 1 year after LT.

RESULTS

At baseline, almost all analyzed coagulation factors were within the normal range, except for FVIII, which was above the normal range. Von Willebrand factor (vWF) and FVIII were increased after LT and remained high at 1 year after transplantation. The cumulative incidence of VTE was 22.9%. Patients who developed VTE had higher FVIII activity 2 weeks after LT.

CONCLUSIONS

This is the first study to describe coagulation profiles up to 1 year after LT. We show that most markers of a procoagulant state normalize at 2 weeks after LT, but that values of FVIII and vWF remain abnormal at 1 year. This problem has received little attention in the literature. Larger studies are necessary to confirm the results and to design appropriate prophylactic strategies.

Precision Medicine in Kidney Transplantation: Just Hype or a Realistic Hope?

Desirable outcomes including rejection- and infection-free kidney transplantation are not guaranteed despite current strategies for immunosuppression and using prophylactic antimicrobial medications. Graft survival depends on factors beyond human leukocyte antigen matching such as the level of immunosuppression, infections, and management of other comorbidities. Risk stratification of transplant patients based on predisposing genetic modifiers and applying precision pharmacotherapy may help improving the transplant outcomes. Unlike certain fields such as oncology in which consistent attempts are being carried out to move away from the "error and trial approach," transplant medicine is lagging behind in implementing personalized immunosuppressive therapy. The need for maintaining a precarious balance between underimmunosuppression and overimmunosuppression coupled with adverse effects of medications calls for a gene-based guidance for precision pharmacotherapy in transplantation. Technologic advances in molecular genetics have led to increased accessibility of genetic tests at a reduced cost and have set the stage for widespread use of gene-based therapies in clinical care. Evidence-based guidelines available for precision pharmacotherapy have been proposed, including guidelines from Clinical Pharmacogenetics Implementation Consortium, the Pharmacogenomics Knowledge Base National Institute of General Medical Sciences of the National Institutes of Health, and the US Food and Drug Administration. In this review, we discuss the implications of pharmacogenetics and potential role for genetic variants-based risk stratification in kidney transplantation. A single score that provides overall genetic risk, a polygenic risk score, can be achieved by combining of allograft rejection/loss-associated variants carried by an individual and integrated into practice after clinical validation.

Analysis of 75 Candidate SNPs Associated With Acute Rejection in Kidney Transplant Recipients: Validation of rs2910164 in MicroRNA MIR146A

BACKGROUND

Identifying kidney allograft recipients who are predisposed to acute rejection (AR) could allow for optimization of clinical treatment to avoid rejection and prolong graft survival. It has been hypothesized that a part of this predisposition is caused by the inheritance of specific genetic variants. There are many publications reporting a statistically significant association between a genetic variant, usually in the form of a single-nucleotide polymorphism (SNP), and AR. However, there are additional publications reporting a lack of this association when a different cohort of recipients is analyzed for the same single-nucleotide polymorphism.

METHODS

In this report, we attempted to validate 75 common genetic variants, which have been previously reported to be associated with AR, using a large kidney allograft recipient cohort of 2390 European Americans and 482 African Americans.

RESULTS

Of those variants tested, only 1 variant, rs2910164, which alters the expression of the microRNA MIR146A, was found to exhibit a significant association within the African American cohort. Suggestive variants were found in the genes CTLA and TLR4.

CONCLUSIONS

Our results show that most variants previously reported to be associated with AR were not validated in our cohort. This shows the importance of validation when reporting the associations with complex clinical outcomes such as AR. Additional work will need to be done to understand the role of MIR146A in the risk of AR in kidney allograft recipients.

Utility of thrombophilia screening in pediatric renal transplant recipients

Thrombosis after kidney transplantation may result in catastrophic outcomes, including graft loss. Thrombophilia has been implicated in post-transplant thrombosis; data, however, are inconclusive on the impact of acquired and inherited thrombophilia and resultant thrombosis in renal graft recipients. We aimed to evaluate whether identifying children with thrombophilia during the pretransplant evaluation predicted post-transplant outcomes. We reviewed 100 kidney transplants performed in 100 children, aged 1-18 years, in a single-center retrospective study. Routine pretransplant comprehensive thrombophilia evaluation was completed. Thrombophilia was demonstrated in 36% patients (N = 36). TEs occurred in 11 patients before kidney transplant. Low PS and antithrombin were found in 9/86 (10.5%) and 2/89 (2.2%) children, respectively. Heterozygosity for FLV and PGM were found in 5/81 (6.2%) and 1/93(1.1%) children, respectively. A post-transplant thrombotic event occurred in 10 children (10%); six involved the renal transplant. The association between a history of a pretransplant thrombotic event and post-operative renal graft thrombosis approached, but did not reach significance (P = 0.071). There was no association between preoperative screening abnormalities and post-operative TEs. Graft loss due to a thrombotic event occurred in two patients; none had underlying thrombophilia. Our data suggest that the utility of universal, comprehensive preoperative thrombophilia testing is not beneficial in determining risk of post-operative graft thrombosis. Thrombophilia testing may be considered in a select population with a history of pretransplant thrombotic event.

Genetics of acute rejection after kidney transplantation

Treatment of acute rejection (AR) following kidney transplantation has improved in recent years, but there are still limitations to successful outcomes. This review article covers literature in regard to recipient and donor genetics of AR kidney and secondarily of liver allografts. Many candidate gene and some genome-wide association studies (GWASs) have been conducted for AR in kidney transplantation. Genetic associations with AR in kidney and liver are mostly weak, and in most cases, the associations have not been reproducible. A limitation in the study of AR is the lack of sufficiently large populations that account for population stratification to study the AR phenotype which in this era occurs in <10% of transplants. Furthermore, the AR phenotype has been difficult to define and the definitions of classifications have evolved over time. Literature related to the pharmacogenomics of tacrolimus is robust and has been validated in many studies. Associations between gene expression and AR are emerging as markers of outcomes and AR classification. In the future, combinations of pretransplant genotype for AR risk prediction, genotype-based immune suppressant dosing, and pharmacogenomic markers to select AR maintenance or treatment and expression markers from biopsies may provide valuable clinical tools for guiding treatment.

Renal transplantation experience in a patient with factor V Leiden homozygous, MTHFR C677T heterozygous, and PAI heterozygous mutation

Vascular complications are important causes of allograft loss in renal transplantation. A two and a half-month-old boy was diagnosed with posterior urethral valve and progressed to end-stage renal disease at eight yr of age. During the HD period, a central venous catheter was replaced three times for repeated thrombosis. The boy was found to be homozygous for FVL and heterozygous for both MTHFR (C677T) and PAI. At the age of 12, renal transplantation was performed from a deceased donor. Postoperative anticoagulation therapy was initiated with continuous intravenous administration of heparin at the dose of 10 IU/kg/h. HD was performed for the first three days. By the fourth day of transplantation, his urine output had increased gradually. Heparin infusion was continued for 18 days during hospitalization at the same dosage. Thereafter, he was discharged with LMWH. On the third month after transplantation, his serum creatinine level was 1.1 mg/dL and eGFR was 75.7 mL/min/1.73 m(2). He has still been using LMWH, and his eGFR was 78.7 mL/min/1.73 m(2) eight months after transplantation. Postoperative low-dose heparin treatment is a safe strategy for managing a patient with multiple thrombotic risk factors.

Successful Living-Related Renal Allograft in a Recipient With Factor V Leiden Deficiency: A Case Report

Thrombophilia due to activated protein C resistance (Leiden mutation) is the most common inherited thrombophilic disorder with 5% incidence in whites. Renal transplant of these patients entails a risk of vascular thrombosis soon after the transplant; and acute rejection episodes and graft loss within the first year. We present a case of a successful living-related renal transplant in man with a recent history of repeat episodes of vascular access thrombosis attributed to inherited thrombophilia (heterozygosity for factor V mutation Q506 and homozygosity for mutation T677 for methylene-tetrahydrofolate reductase). Transplant recipient was administered anticoagulation therapy with low molecular weight heparin pre- and postoperatively. No thrombotic or hemorrhagic events occurred posttransplant. A high suspicion of thrombophilic disorders in patients with end-stage renal disease with vascular access thrombotic events should be screened further to prevent failure of a subsequent renal transplant. Inherited thrombophilic disorders may not exclude living-related kidney transplant provided that anticoagulation therapy is admin-istered perioperatively.

End-stage renal disease and thrombophilia

Chronic kidney disease is an established risk factor for arterial and venous thromboembolism (TE). Whereas the overall risk of TE in moderately decreased kidney function is approximately 2.5-fold higher compared to patients with normal renal function, the risk increase is 5.5-fold in patients with severe renal dysfunction. In patients with renal dysfunction and arterial thrombosis (OR: 4.9), malignancy (OR: 5.8) surgery (OR: 14.0) or thrombophilia (OR: 4.3) the risk to suffer from venous TE is higher compared to the risk associated to the baseline renal dysfunction alone. The treatment options for end-stage renal diseases include hemodialysis, peritoneal dialysis and kidney transplantation. During all treatment modalities thrombotic complications have been described, namely catheter malfunction and shunt thrombosis in patients undergoing hemodialysis in up to 25% of patients, and TE, pulmonary embolism or graft vessel thrombosis in approximately 8% of patients. The reported incidence of reno-vascular thrombosis following renal transplantation leading to hemorrhagic infarction with organ rejection or organ loss varied between 2-12%. Keeping in mind the multifactorial etiology of TE in patients with kidney dysfunction a general screening for thrombophilia in this patient group is not indicated. Selected screening on an individual patient basis should be discussed if the family history for TE is positive or the patient itself had suffered one thrombosis before the onset of the renal disease or multiple TEs during hemodialysis or post kidney transplantation in patients waiting for living donor kidney transplantation.

ABO incompatible renal transplantation without antibody removal using conventional immunosuppression alone

ABO incompatible living donor renal transplantation (ABOi) can achieve outcomes comparable to ABO compatible transplantation (ABOc). However, with the exception of blood group A2 kidneys transplanted into recipients with low titer anti-A antibody, regimens generally include antibody removal, intensified immunosuppression and splenectomy or rituximab. We now report a series of 20 successful renal transplants across a range of blood group incompatibilities using conventional immunosuppression alone in recipients with low baseline anti-blood group antibody (ABGAb) titers. Incompatibilities were A1 to O (3), A1 to B (2), A2 to O (2), AB to A (2), AB to B (1), B to A1 (9), B to O (1); titers 1:1 to 1:16 by Ortho. At 36 months, patient and graft survival are 100%. Antibody-mediated rejection (AbMR) occurred in one patient with thrombophilia and low level donor-specific anti-HLA antibody. Four patients experienced cellular rejection (two subclinical), which responded to oral prednisolone. This series demonstrates that selected patients with low titer ABGAb can undergo ABOi with standard immunosuppression alone, suggesting baseline titer as a reliable predictor of AbMR. This reduces morbidity and cost of ABOi for patients with low titer ABGAb and increases the possibility of ABOi from deceased donors.

Mechanical thromboprophylaxis is sufficient to prevent the lower extremity deep vein thrombosis after kidney transplantation

Purpose

Deep vein thrombosis (DVT) is a severe and common complication that occurs after the major operation. Despite the commonality of DVT there is limited data on the incidence of DVT after kidney transplantation (KT). Furthermore, most studies have been retrospective in design and were conducted in western countries. The aim of this study was to evaluate the incidence of lower extremity DVT with mechanical thromboprophylaxis within 1 month of KT in Korea.

Methods

A total of 187 consecutive patients who underwent KT were included in this study. Patients used a graduated elastic stocking (n = 93) or an intermittent pneumatic compression device (n = 94) to prevent DVT. The frequency of DVT during the first month after KT was evaluated using serial color duplex ultrasound on postoperative days 7 ± 2, 14 ± 2, and 28 ± 3. All patients were tested for eight thrombophilic factors before KT.

Results

DVT occurred in four patients (2.1%) during the first month after KT. All DVT developed in the graduated elastic stocking group. Interestingly, none of the patients had the factor V Leiden mutation or the prothrombin gene 20210A mutation.

Conclusion

The incidence of DVT in this study was relatively lower than that of western populations. We did not encounter a factor V Leiden mutation or a prothrombin gene 20210A mutation in our study population. These findings suggest that inherited thrombophilic risk factors may be partially responsible for the difference in DVT incidence rates between different nationalities and/or ethnicities.

Successful living donor kidney transplantation in a patient with prothrombin gene mutation: Case report and literature review

We present a patient with known prothrombin gene mutation and a history of prior vascular events, who underwent living donor kidney transplantation. Given the presumed elevated risk of complication from known prothrombin mutation, clinical management was directed towards optimizing living donor allograft function.

Splanchnic vein thrombosis following renal transplantation: a case report

Background

Recurrent episodes of venous thrombosis have been closely correlated with JAK2 V617F mutation. Upto date, JAK2 gene mutation has not been defined as a prothrombic risk factor in renal transplant recipients. Herein; we present a case of portosplenic vein thrombosis in a primary renal transplant recipient with JAK2 V617F mutation who had no history of prior venous thromboembolism or thrombophilia.

Case presentation

A 59 year old female caucasian patient with primary kidney transplant admitted with vague abdominal pain at left upper quadrant. Abdominal doppler ultrasound and magnetic resonance imaging angiography demonstrated splanchnic vein thrombosis (SVT). The final diagnosis was SVT due to MPD (essential thrombocytosis, ET) with JAK2 V617F mutation. After 3 months of treatment with warfarin (≥5 mg/day, to keep target INR values of 1.9-2.5), control MRI angiography and doppler USG demonstrated partial (>%50) resolution of thrombosis with recanalization of hepatopedal venous flow. The patient is still on the same treatment protocol without any complication.

Conclusion

JAK2 V617F mutation analysis should be a routine procedure in the diagnosis and treatment of kidney transplant patients with thrombosis in uncommon sites.

Associations of pre-transplant anemia management with post-transplant delayed graft function in kidney transplant recipients

BACKGROUND

Delayed graft function (DGF) complicates kidney allograft outcomes in the immediate post-transplantation period. We hypothesized that in hemodialysis patients more severe anemia, iron deficiency, the requirement for higher doses of erythropoietin-stimulating agents (ESA), or blood transfusions prior to transplantation are associated with higher risk of DGF.

METHODS

Linking five-yr hemodialysis patient data of a large dialysis organization to the Scientific Registry of Transplant Recipients, we identified 11 836 hemodialysis patients. Using logistic regression analyses we examined the association between pre-transplant parameters and post-transplant DGF.

RESULTS

Patients were 49 ± 14 (mean ± SD) yr old and included 38% women, 27% blacks, and 26% diabetics. After adjusting for relevant covariates, pre-transplant blood transfusion was associated with 33% higher DGF risk (odds ratio [OR] = 1.33; 95% confidence interval [CI]: 1.19-1.48); and each 5000 U/wk increase of pre-transplant ESA dose with 5% higher DGF (OR = 1.05; 95% CI: 1.02-1.09). Compared to pre-transplant blood hemoglobin of 12-12.99 g/dL, there was 25% higher risk of DGF with blood hemoglobin 10-10.99 g/dL (OR = 1.25; 95% CI: 1.01-1.55), whereas blood hemoglobin ≥13 g/dL exhibited 15% higher risk of DGF (OR = 1.15; 95% CI: 0.98-1.34).

CONCLUSIONS

Pre-transplant blood transfusion, higher ESA dose, and either high or low blood hemoglobin but not iron markers are associated with higher risk of DGF.

Modifiers of complement activation for prevention of antibody-mediated injury to allografts

PURPOSE OF REVIEW

Improvements in prevention and management of cellular rejection of solid organ transplants, coupled with increasing numbers of sensitized patients, have focused attention on antibody-mediated rejection (AbMR). Complement is a critical component of AbMR, in addition to interfacing between innate and adaptive immunity and the coagulation cascade. This article reviews complement biology and strategies to overcome complement in AbMR, cognisant that antibody can act independently of complement.

RECENT FINDINGS

The past decade has witnessed an improvement in the prevention and treatment of AbMR as a result of solid-phase assays to determine antibody specificity, definition of histopathological criteria, and use of plasmapheresis and/or intravenous immunoglobulin (IVIG). Nonetheless, AbMR continues to impact adversely on short- and long-term graft survival. Use of B and/or T-lymphocyte-depleting therapies has not shown measurable benefit, and the need remains for therapies that deplete antibody, or provide better protection from complement-mediated damage. Disordered complement activity in human diseases such as paroxysmal nocturnal haemoglobinuria, has provided additional impetus to pursuing therapeutic complement inhibition. Preliminary data from C5 inhibition with eculizumab in the treatment and prevention of AbMR have shown promise. Trials with recombinant human inhibitors of C1 (effective in angioedema) to prevent or treat AbMR are beginning.

SUMMARY

Despite current limitations, 'protection' of the transplant through plasmapheresis and/or IVIG enables many allografts to survive in sensitized recipients. Elucidating the pathways mediating graft acceptance, by constitutive antibody deletion, or 'accommodation' (wherein donor organ remains uninjured despite antibody binding), or other local protective mechanism(s), is an equally important challenge in the quest to overcome AbMR.

[Incidence of thrombophilia and risk of renal vessel thrombosis in kidney transplant recipients]

INTRODUCTION

Kidney transplantation is the optimal treatment of end stage kidney disease. The most common vascular complication in the early postoperative period is thrombosis of the renal artery and vein. These complications usually lead to the loss of the transplanted kidney.

AIM

of our study was to identify those factors which represent an increased risk for thrombotic complication and determine whether routine screening for thrombophilia is justifiable before transplantation. As an illustration to this problem we report a case of successful renal vein recanalisation after thrombosis.

METHODS

We give an overview of the literature about incidence of renal graft thrombosis, hypercoagulable states, predictive value of factor V. Leiden and prothrombin G20210A mutations in venous thromboembolism. We discuss those publications that suggest a preoperative screening of transplant candidates for hypercoagulable states and thrombophilia and those that do not think that such screening is reasonable. In our case a 28 year old male patient received a cadaveric kidney. Thrombosis of the renal vein was diagnosed 8 hours after transplantation. Reoperation was performed immediately: venous anastomosis was opened, the thrombus removed. After reoperation the circulation of the kidney recovered, intravenous heparin treatment was introduced immediately.

RESULTS

24 months later the kidney is still functioning well. Postoperative thrombophilia screening showed heterozygosity for factor V Leiden.

CONCLUSION

There are only few publications reporting on successful recanalisation after renal vein thrombosis. In our case rapid diagnosis and immediate operative treatment saved the graft. There is no uniform proposal in the literature whether preoperative screening for thrombophilia is justifiable or not. In our view screening for thrombophilia and thromboprophylaxis is mandatory. Extensive prospective studies should be undertaken to refine the risks and establish the associations of thrombophilia and thromboembolism after kidney transplantation.

Thrombophilic mutations: no association with thrombotic events in renal transplant recipients

Factor V Leiden and mutation of prothrombin gene G20210A have been associated with poor results in the early post-kidney transplantation period. Its long-term importance in stable patients has yet to be evaluated. We studied the prevalence of these inherited mutations and their relationship to thrombotic events in 82 Argentine renal transplant recipients with adequate long-term kidney function. In aggregate, 7.2% of patients were carriers of these mutations; however, their presence did not show any association with thrombotic events or renal function alterations. The routine evaluation for these mutations does not seem to be cost-effective in renal transplant patients.

Thrombophilic factors do not predict outcomes in renal transplant recipients under prophylactic acetylsalicylic acid

A cohort of recipients of renal transplant after 2000 (N=310) was prospectively screened on the day of transplantation and 1 month later for a panel of 11 thrombophilic factors to assess their effect on posttransplant outcomes. All patients received prophylactic acetylsalicylic acid, started before transplantation. The rate of thromboembolic events or acute rejection episodes during the first posttransplant year (primary composite endpoint) was 16.7% among patients free of thrombophilic factor (N=60) and 17.2% in those with >or=1 thrombophilic factor (N=250) (p>0.99). The incidence of the primary endpoint was similar among patients free of thrombophilic factors and those with >or=2 (N=135), or >or=3 (N=53) factors (16.3% and 15.1% respectively; p=1) and in patients who remained thrombophilic at 1 month (15.7%; p=0.84). None of the individual thrombophilic factor present at the day of transplantation was associated with the primary endpoint. The incidence of cardiovascular events at 1-year, serum creatinine at 1-year, 4-year actuarial graft and patient survival were not influenced by the presence of >or=1 thrombophilic factor at baseline (p=NS). In conclusion, the presence of thrombophilic factors does not influence thromboembolic events, acute rejection, graft or patient survival in patients transplanted after 2000 and receiving prophylactic acetylsalicylic acid.

Disease recurrence in paediatric renal transplantation

Renal transplantation (Tx) is the treatment of choice for end-stage renal disease. The incidence of acute rejection after renal Tx has decreased because of improving early immunosuppression, but the risk of disease recurrence (DR) is becoming relatively high, with a greater prevalence in children than in adults, thereby increasing patient morbidity, graft loss (GL) and, sometimes, mortality rate. The current overall graft loss to DR is 7-8%, mainly due to primary glomerulonephritis (70-80%) and inherited metabolic diseases. The more typical presentation is a recurrence of the full disease, either with a high risk of GL (focal and segmental glomerulosclerosis 14-50% DR, 40-60% GL; atypical haemolytic uraemic syndrome 20-80% DR, 10-83% GL; membranoproliferative glomerulonephritis 30-100% DR, 17-61% GL; membranous nephropathy approximately 30% DR, approximately 50% GL; lipoprotein glomerulopathy approximately 100% DR and GL; primary hyperoxaluria type 1 80-100% DR and GL) or with a low risk of GL [immunoglobulin (Ig)A nephropathy 36-60% DR, 7-10% GL; systemic lupus erythematosus 0-30% DR, 0-5% GL; anti-neutrophilic cytoplasmic antibody (ANCA)-associated glomerulonephritis]. Recurrence may also occur with a delayed risk of GL, such as insulin-dependent diabetes mellitus, sickle cell disease, endemic nephropathy, and sarcoidosis. In other primary diseases, the post-Tx course may be complicated by specific events that are different from overt recurrence: proteinuria or cancer in some genetic forms of nephrotic syndrome, anti-glomerular basement membrane antibodies-associated glomerulonephritis (Alport syndrome, Goodpasture syndrome), and graft involvement as a consequence of lower urinary tract abnormality or human immunodeficiency virus (HIV) nephropathy. Some other post-Tx conditions may mimic recurrence, such as de novo membranous glomerulonephritis, IgA nephropathy, microangiopathy, or isolated specific deposits (cystinosis, Fabry disease). Adequate strategies should therefore be added to kidney Tx, such as donor selection, associated liver Tx, plasmatherapy, specific immunosuppression protocols. In such conditions, very few patients may be excluded from kidney Tx only because of a major risk of DR and repeated GL. In the near future the issue of DR after kidney Tx may benefit from alternatives to organ Tx, such as recombinant proteins, specific monoclonal antibodies, cell/gene therapy, and chaperone molecules.

Lung transplantation in a patient with a thrombophilic disorder

The prothrombin G20210A mutation has been associated with an increased risk of graft failure in renal transplant recipients. Little is known about the potential effect of this mutation on lung transplant recipients. We report the case of bilateral lung transplantation in a patient with cystic fibrosis who was heterozygous for the G20210A mutation of the prothrombin gene.

Right atrial thrombosis complicating renal transplantation in a child

Nephrotic syndrome represents a form of acquired thrombophilia thereby causing increased risk of thrombosis. In patients with nephrotic syndrome both venous and arterial thrombosis can occur; however, intracardiac thrombus is among the rarest reported in the literature. In this case report, we present a 10.5-yr-old boy with right atrial thrombosis and an acute rejection episode after renal transplantation due to end stage renal disease caused by focal segmental glomerulosclerosis manifested by nephrotic syndrome. The clinical course was successfully managed with surgical removal of thrombus, institution of anticoagulant as well as antirejection therapy. This report draws attention to the risks that could be associated with thrombosis in renal recipients with congenital or acquired thrombophilias and emphasizes the importance of identifying risk factors for thrombosis in these patients.

Venous Graft Thrombosis in Patients on Peritoneal Dialysis Before Transplantation

BACKGROUND

It has been described that patients on peritoneal dialysis (PD) suffer from thrombotic events (vascular access, deep venous thrombosis, and graft thrombosis) more frequently after transplantation than other recipients. We analyzed the incidence of allograft thrombosis among patients transplanted in a 6-year period (January 1, 2000, to December 31, 2005) to identify etiological factors, such as inherited thrombophilia.

MATERIALS AND METHODS

We performed 197 renal transplants in 189 patients, including 115 who had been on hemodialysis (HD), 44 on PD, and 30 preemptive. We recorded immunological and demographic data, studied graft and patient survivals, and evaluated the hypercoagulable state of those who experienced graft thrombosis.

RESULTS

The mean age of the patients at transplantation was 49 years. There were no demographic or immunological differences between the three groups of patients, except for the number of previous blood transfusions and panel reactive antibodies (PRA) levels. Forty-seven grafts were lost in the first year; 14 suffered venous thrombosis, and there were 10 acute rejection epidoses (ARE), 7 death-censored graft failures, 3 chronic allograft nephropathies (CAN), 6 primary nonfunctions, 5 removed due to infection, 1 primary disease relapse, and 1 hemolytic-uremic syndrome. Of the 14 cases of thrombosis in 12 patients, 10 had been on PD and 4 on HD immediately before transplant. One-year graft and patient survivals were similar: 74% HD, 68% PD, 86% preemptive, and 93% HD, 95% PD, and 96% preemptive, respectively. The hypercoagulable state showed inherited thrombophilia patterns in some cases, but most of them were normal.

CONCLUSION

Renal graft thrombosis was responsible for graft lost in PD patients within the first year, while in the HD group it was ARE and in the preemptive cohort, death with a functioning graft. The hypercoagulable state pretransplant should be more accurately studied to identify thrombotic factors other than those which are inherited.

No Association of Factor V Leiden, Prothrombin G20210A, and MTHFR C677T Gene Polymorphisms With Kidney Allograft Survival: A Multicenter Study

BACKGROUND

It has been proposed that inherited risk factors of venous thromboembolism, such as factor V G1691A (FV-Leiden), prothrombin G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T, might be associated with poorer survival rates of transplanted kidneys. On the basis of this hypothesis, we performed a multicenter study, involving recipients of primary and repeat kidney transplants, to investigate the potential effect of these three single nucleotide polymorphisms (SNP) on graft survival.

METHODS

The study consisted of 676 first and 651 retransplant patients. Using the polymerase chain reaction-sequence specific primers method, we typed all patients for the three SNP and analyzed graft survival.

RESULTS

We could not find a statistically significant association between graft survival and factor V Leiden or MTHFR C677T genotypes. A better 3-yr graft survival was found for first transplant recipients with the genotype prothrombin 20210 G/G as compared to those with the G/A genotype (P=0.031). However, Bonferroni correction for the three SNPs investigated in this series rendered the P value insignificant (P(corrected)=0.093).

CONCLUSION

We did not find a statistically significant association of SNP factor V Leiden G1691A and MTHFR C677T with renal graft survival. Prothrombin G20210A resulted in a significant association that was not sustained after Bonferroni correction. This SNP might be an interesting candidate for future studies.

Do inherited hypercoagulable states play a role in thrombotic events affecting kidney/pancreas transplant recipients?

BACKGROUND

Pancreas graft thrombosis remains the leading non-immunologic cause of graft loss after pancreas transplantation. We studied the role of hypercoagulable states (HCS) in pancreas graft thrombosis (pthx).

METHODS

Between January 1, 1994, and January 1, 2003, 131 pancreas transplant recipients experienced a pthx (n = 67) or other thrombotic events. Fifty-six recipients consented to have their blood drawn and tested for the HCS. These results were compared with a control group of pancreas transplant recipients who did not experience a thrombotic event. Fisher's exact test was used to compare the groups.

RESULTS

We found 18% of the recipients with pancreas thrombosis to have a HCS. Factor V Leiden (FVL) was found in 15% vs. 4% in the control group (p = ns) vs. 3-5% in the general white population. We found 3% of the pancreas thrombosis patients to have a prothrombin gene mutation (PGM) vs. 0% in the control group (p = ns) vs. 1-2% in the general white population.

CONCLUSIONS

Of pancreas transplant recipients with thrombosis, 18% had one or more of the most common factors associated with a HCS (FVL or PGM). This can be compared with 4% in a control group and 4-7% in the general white population, respectively. Although the differences are not statistically significant due to small numbers, we feel that the findings may be clinically relevant. While this is only a pilot study, it may be reasonable to screen select pancreas transplant candidates for HCS, especially FVL and PGM, until more data become available.

Outcome after kidney transplantation in children with thrombotic risk factors

BACKGROUND

According to the data from the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS), vascular thrombosis accounts for 11.6% of graft losses in pediatric renal transplantation. In adults, inherited and acquired thrombophilic risk factors, e.g. factor V Leiden mutation, have been associated with early graft loss and increased rejection episodes. Data on the impact of these factors on the outcome of children after renal transplantation are rare.

METHODS/PATIENTS

Sixty-six pediatric patients awaiting renal transplantation (mean age 10.1 yr) were screened for inherited and acquired risk factors for hypercoagulable disorders (protein C, S, and antithrombin III deficiency, antiphospholipid antibodies, factor V Leiden, prothrombin, and MTHFR mutation) in order to intensify anticoagulation in those with an increased risk for thrombophilia: intravenous heparin was administered with a partial prothrombin time (PTT) prolongation of 50 s for 14 days and switched to low-molecular-weight heparin for another 8 wk before aspirin was introduced for the first year. Patients without hypercoagulable risk factors were treated with heparin without PTT prolongation for 14 days and switched to aspirin immediately afterwards. The results on graft survival, incidence of acute rejection episodes, and long-term renal graft function were analyzed between recipients with and without hypercoagulable risk factors.

RESULTS

Thrombophilic risk factors were identified in 27.3% of our patients. No thrombosis occurred. One serious bleeding complication led to a second surgical intervention. The rate of acute rejection episodes was not increased in patients with and without thrombotic risk factors after 90 days (16.7 vs. 25%), 1 yr (22.2 vs. 33.3%), and 3 yr (38.9 vs. 41.7%) of follow-up, respectively (p = n.s.). After a mean follow-up of 3 yr the kidney function was comparable in both groups, with 63.1 in recipients with and 69.8 mL/min/1.73 m(2) in recipients without hypercoagulable risk (p = n.s.). At latest follow-up, three graft losses were found not to be attributed to thrombotic risk factors.

INTERPRETATION

Children with thrombophilic risk factors were identified and treated with an intensified anticoagulation regimen after renal transplantation. An increased risk for graft failure, acute rejection episodes, or impaired renal function for pediatric renal transplant recipients with hypercoagulable status was not found.

Successful renal transplantation in a patient with heterozygous prothrombin gene, factor V Leiden mutation and heparin-induced thrombocytopenia using r-hirudin as anticoagulant

Vascular complications remain the most common cause of early renal allograft loss in patients with end-stage renal failure. Underlying thrombophilic disorders increase the risk of early graft thrombosis. A male adolescent with high-risk thrombophilia because of combined heterozygous factor V Leiden (G1691A) and prothrombin gene (G20210A) mutation developed HIT II. Hemodialysis and subsequent renal transplantation were undertaken using recombinant hirudin, a direct and selective thrombin inhibitor, as an anticoagulant. Primary function in the transplanted kidney was excellent. No thrombotic or hemorrhagic events have occurred and follow-up showed excellent long-term graft survival. Patients on HD have an increased risk for the development of HIT, and therefore, they need repetitive screening for the development of acquired thrombotic risk factors (e.g. HIT II or lupus anticoagulant). R-hirudin is efficacious and safe on both HD and following renal transplantation.

Management of Hereditary Hypercoagulable Disorders

The clinical management of individuals with hereditary hypercoaguable disorders has evolved from initial broad recommendations of lifelong anticoagulation after first event of venous thromboembolism to a more intricate individualized risk-benefit analysis as studies have begun to delineate the complexity of interactions of acquired and hereditary factors which determine the predilection to thrombosis. The contribution of thrombophilic disorders to risk of thrombotic complications of pregnancy, organ transplantation, central venous catheter and dialysis access placement have been increasingly recognized. The risk of thrombosis must be weighed against risk of long-term anticoagulation in patients with venous thromboembolism. Thrombophilia screening in select populations may enhance outcome.

[Modern immunosuppression following renal transplantation. Standard or tailor made?]

Renal transplantation is by far the best therapeutic option for end-stage kidney disease with respect to quality of life, psychosocial rehabilitation, and even patient survival. Optimal immunosuppressive therapy should provide effective prophylaxis of both acute rejection and chronic allograft dysfunction. Thus immunosuppressive therapy should help to maintain good renal function and could help to prevent premature death of the recipient. With the introduction of new immunosuppressants over the last decade a dramatic reduction of acute rejection rates from approximately 50% to 15-30% could be achieved. However, the search for novel immunosuppressive drugs continues, drugs which not only lead to effective prevention of acute rejection, but also have an impact on chronic allograft dysfunction and prevent further deterioration of this multifactorial process. Based on a short presentation of the "three signal model" of immunoactivation, the most important mechanisms and characteristics of the presently available immunosuppressants are described. Because the immunosuppressive objectives change over time, a phase-dependent adaptation is necessary. At present, most centers in Germany use an immunosuppressive combination therapy, consisting of a calcineurin inhibitor (CNI; cyclosporine or tacrolimus), a glucocorticoid (prednisolone or methylprednisolone), and mycophenolic acid (MPA), which is eventually combined with an antibody (e.g., IL-2R antibody) for induction. In contrast to the clear situation 10 years ago, highly specialized knowledge is required today with respect to mechanism of action, side effects, and potential interactions. This may enable the physician to adopt patient-oriented optimal immunosuppression. In the near future more individualized treatment options will be employed, which are adapted to the characteristics and side effects of the immunosuppressant, as well as to the characteristics of the donor, the recipient, and the transplanted organ such as immunology and ischemia. Another aspect is the reduction or elimination of some immunosuppressants at the earliest possible time. With new diagnostic and genetic markers the relationship between recipient and transplanted organ will be characterized better in the future and therapy will become more individualized. Altogether, these measures as well as optimized supportive therapy will help to further improve the longevity of the transplanted organ.

Effects of single-nucleotide polymorphisms in MTHFR and MTRR on mortality and allograft loss in kidney transplant recipients

BACKGROUND

Plasma total homocysteine (tHcy) is associated with cardiovascular outcomes in kidney transplant recipients (KTR). The methylenetetrahydrofolate-reductase (MTHFR) 677C>T polymorphism, an important determinant of plasma tHcy concentrations, could therefore constitute an important prognostic marker.

METHODS

We prospectively followed 710 KTR over >6 years. The MTHFR677C>T, MTHFR1298A>C, MTHFR1793G>A, and MTRR66A>G polymorphisms were analyzed. Demographic, clinical, and transplant-related information was obtained, and patients were followed-up using the Austrian Dialysis and Transplant Registry. Using Cox regression, we established the independent relations of each genotype to the risk of death from any cause, and/or kidney allograft loss.

RESULTS

During a median follow-up of 6.1 years, 154 participants died and 260 kidney allografts were lost. Compared to patients with the MTHFR677CC genotype, patients with MTHFR677CT had an adjusted relative mortality risk of 1.02 (95%CI 0.70-1.47), and those with MTHFR677TT of 0.98 (95%CI 0.52-1.85). Compared to MTHFR677CC, the relative risks of kidney allograft loss were 0.93 (95%CI 0.70-1.23; MTHFR677CT) and 0.78 (95%CI 0.47-1.30; MTHFR677TT), respectively. None of the other genotypes were associated with the risks studied, either. These findings did not depend on whether we controlled for tHcy levels.

CONCLUSION

This study does not support the routine use of MTHFR or MTRR genotyping for prognostic evaluation or risk-stratification in kidney transplant recipients.

Thromboembolism in Heart Transplantation: Role of Prothrombin G20210A and Factor V Leiden

BACKGROUND

Thromboembolism has been reported as a frequent complication after cardiac transplantation. Many risk factors for thrombosis may explain this, such as metabolic alterations and the use of cyclosporine. In the general population, two single nucleotide polymorphisms (SNPs), factor V Leiden and prothrombin G20210A (PT G20210A), have been associated with a significant increase in the risk of thrombosis. However, these mutations have not been analyzed in cardiac transplant patients. We describe the protracted history of recurrent thromboembolism in a rare case of homozygosity for the PT G20210A variant. This prompted us to analyze the entire cardiac transplant cohort for the incidence of thromboembolic events and their association with these genetic polymorphisms.

METHODS

We report the study of 84 cardiac transplant recipients. We retrospectively analyzed the frequency of thromboembolic episodes. The genotypes for FVL and PT G20210A were determined and correlated with those episodes.

RESULTS

Our results confirm a very high incidence of thromboembolism in this population. We also found a significant increase in the likelihood of thromboembolism in subjects with the PTB G20210A variant (odds ratio 3.08; 95% confidence interval: 1.7-5.5).

CONCLUSIONS

The incidence of thromboembolic complications after heart transplantation is increased and may be related in part to genetic predisposition.

Association of plasma homocysteine with serum interleukin-6 and C-peptide levels in patients with type 2 diabetes

Hyperhomocysteinemia is an independent risk factor for atherosclerotic disease. Because serum markers of inflammation and the metabolic syndrome are also associated with atherosclerotic disease and insulin resistance, we investigated whether plasma homocysteine (Hcy) levels were associated with serum markers of inflammation and factors of metabolic syndrome in 223 elderly patients with type 2 diabetes mellitus. The levels of plasma Hcy and serum interleukin-6 (IL-6), high-sensitivity C-reactive protein, and C-peptide were measured. The C677T mutation of methylenetetrahydrofolate reductase (MTHFR) gene was detected using the polymerase chain reaction-restriction fragment length polymorphism method. The number of abnormal metabolic factors (presence of diabetes, blood pressure > or =130/85 mm Hg, triglycerides > or =150 mg/dL, high-density lipoprotein cholesterol <35 mg/dL (men) or <39 mg/dL (women), or body mass index >25 kg/m 2 ) was assessed. Elevated plasma Hcy levels correlated significantly with serum IL-6 ( r = 0.25, P < .001), C-peptide ( r = 0.22, P < .01), and the number of abnormal metabolic factors ( r = 0.20, P < .01), but not with C-reactive protein. Multiple linear regression analysis revealed that log-transformed IL-6, serum C-peptide, vitamin B12 , and creatinine were significant determinants of plasma Hcy levels. The correlation between Hcy and IL-6 levels was strongest in those with TT genotype of C677T MTHFR among 3 genotypes. The association between plasma Hcy and serum IL-6 levels supports the hypothesis that the activation of innate immunity is involved in the pathogenesis of arteriosclerosis in patients with diabetes mellitus who are homozygous for the TT genotype of C677T MTHFR.

No Increase in Rejection or Graft Loss in Kidney Transplant Recipients With Thrombophilia Treated With Anticoagulation and Triple Immunosuppression

INTRODUCTION

Recent studies from Europe have demonstrated that patients with end-stage renal disease who receive a kidney transplant are at an increased risk for rejection and graft loss when compared with patients who have no known thrombophilia. The role of anticoagulation has not been investigated in these patients.

MATERIALS AND METHODS

We prospectively tested patients who were evaluated for a kidney transplant for 8 thrombophilias, protein S and C deficiencies, factor V Leiden mutation, antithrombin III deficiency, anticardiolipin antibody, lupus anticoagulant, prothrombin gene mutation, and heparin-induced platelet antibody (HIPA). Patients with any identified thrombophilia received heparin or argatroban (for HIPA (+) patients) followed by coumadin for 1 year after transplantation. Triple therapy included cyclosporine, prednisone, and CellCept (Roche Pharmaceuticals, Nutley, NJ, USA). Sensitized, black, or repeat transplantation patients received induction with an interleukin (IL)-2 inhibitor. Data were collected in a retrospective manner. Rejection was biopsy-proven.

RESULTS

Of the 112 transplant recipients who were tested for thrombophilia, 37 had 1 or more thrombophilia and 75 had no thrombophilia identified. Twenty-six patients received heparin and 11 received argatroban. There were no differences in recipient age, cold storage time, graft loss, HLA match, rejection episodes, 1-year graft survival, or serum creatinine level at 1 year. Significant differences were noted in posttransplantation bleeding, 35% versus 5%, and delayed graft function, 32% versus 15%, in patients with thrombophilia versus no thrombophilia, respectively.

CONCLUSION

This is the first study to demonstrate that there is no increase in rejection or graft loss in kidney transplant recipients with thrombophilia when treated with anticoagulation and triple immunosuppression.

Delayed graft function in kidney transplantation

Delayed graft function is a form of acute renal failure resulting in post-transplantation oliguria, increased allograft immunogenicity and risk of acute rejection episodes, and decreased long-term survival. Factors related to the donor and prerenal, renal, or postrenal transplant factors related to the recipient can contribute to this condition. From experimental studies, we have learnt that both ischaemia and reinstitution of blood flow in ischaemically damaged kidneys after hypothermic preservation activate a complex sequence of events that sustain renal injury and play a pivotal part in the development of delayed graft function. Elucidation of the pathophysiology of renal ischaemia and reperfusion injury has contributed to the development of strategies to decrease the rate of delayed graft function, focusing on donor management, organ procurement and preservation techniques, recipient fluid management, and pharmacological agents (vasodilators, antioxidants, anti-inflammatory agents). Several new drugs show promise in animal studies in preventing or ameliorating ischaemia-reperfusion injury and possibly delayed graft function, but definitive clinical trials are lacking. The goal of monotherapy for the prevention or treatment of is perhaps unattainable, and multidrug approaches or single drug targeting multiple signals will be the next step to reduce post-transplantation injury and delayed graft function.

Significance of anticardiolipin antibodies on short and long term allograft survival and function following kidney transplantation

The significance of anticardiolipin antibodies (ACAs) prior to renal transplantation is unclear. We studied a cohort of 337 patients who underwent renal transplantation from 1996 to 2001. Follow-up continued until allograft loss, patient death or 31 December 2002. The primary outcome was a composite endpoint of death-censored allograft loss or a 25% reduction in estimated glomerular filtration rate (GFR) from 1-month post-transplant. Secondary outcomes were allograft loss, a 25% reduction in GFR, acute rejection and creatinine at 1 year. IgG and IgM ACA titers were positive (> or =15) in 18.1% of recipients. There were no significant differences at baseline between recipients, except coumadin therapy in those with positive ACA titers (20% vs. 7.4%). Post-transplant, there was no increase in the primary outcome in ACA-positive patients, even after adjustment for anticoagulation with coumadin (HR = 1.42 [0.68, 2.96]). There was no difference in secondary outcomes between those with or without positive titers. Two of five patients with very high titers (>50) who were not anticoagulated had early graft loss. A positive ACA titer prior to kidney transplantation was not associated with inferior renal outcomes after transplantation, although more research is required to address the prognostic significance of very high ACA titers.

Hypercoagulability in renal transplant recipients. Identifying patients at risk of renal allograft thrombosis and evaluating strategies for prevention

Renal transplantation improves survival and quality of life for patients with end-stage renal disease (ESRD). Improvements in immunosuppressive therapy have reduced early allograft loss due to acute rejection to very low levels. Early allograft loss, due to acute thrombotic complications, remains a constant and proportionally increasing complication of renal transplantation. Identifying risk factor(s) for thrombosis amenable to preventive strategies has been elusive. Epidemiological studies have attempted to define risk in terms of modifiable (drugs, dialysis modality, surgical procedure) and non-modifiable (age, diabetes mellitus, vascular anomalies) factors, or identify changes in coagulation or fibrinolysis promoting a more thrombotic state. Most recently the evolution of thrombophilia research has established the potential for inherited hypercoagulability to predispose to acute allograft thrombosis. Inheritance of the factor V Leiden (FVL), prothrombin G20210A mutation, or the presence of antiphospholipid antibodies (APA) may increase the risk of renal allograft thrombosis approximately 3-fold in selected patients. Patients with ESRD due to systemic lupus erythematosus (SLE) appear at particularly high risk of thrombosis, especially if they have either APA or detectable beta(2)-glycoprotein-1. Data for other hypercoagulable states such as hyperhomocystinemia or the C677T polymorphism of the methylenetetrahydrofolate reductase gene are deficient. Patients with APA, FVL, or prothrombin G20210A mutation also appear to have greater graft loss due to vascular rejection, possibly reflecting immunological injury upon the vascular wall exacerbated or induced by the prothrombotic state. While substantial in vitro data suggest cyclosporine is prothrombotic, an independent clinical association with allograft thrombosis is unproven. Interventions to reduce thrombotic risk including heparin, warfarin, and aspirin have been evaluated in both selected high-risk groups (heparin and warfarin) and unselected populations (heparin and aspirin). In unselected patients at low clinical risk, aspirin (75-150 mg/day) with or without a short period of unfractionated heparin (5000U twice a day for 5 days) appears to reduce the risk of renal allograft thrombosis significantly with a low risk of bleeding, especially when compared with low molecular weight heparins which risk accumulation in renal failure. In high-risk groups (identified thrombophilic risk factor, previous thrombosis, or SLE) longer period of heparin, with or without aspirin and maintenance with warfarin, should be considered. Re-transplantation following graft loss due to vascular thrombosis can be undertaken with a low risk of recurrence. Further prospective studies evaluating both putative risk factors and intervention strategies are required to determine whether routine clinical screening for thrombophilic factors is justified.

Is there additional effect of MTHFR C677T mutation on lipid abnormalities in renal allograft recipients?

BACKGROUND

The MTHFR C677T mutation and elevated atherogenic lipoprotein levels are known as cardiovascular risk factors in patients with renal transplantation treated with cyclosporine (CsA). The aim of the present study was to eveluate the contribution of MTHFR C677T mutation to the risk of dyslipidemia in renal transplant recipients. We also studied the effect of the MTHFR-C677 T genotype on transplant survival.

METHODS

The study included 29 nondiabetic renal transplant recipients and 27 healthy controls. MTHFR C677T genotypes were determined by PCR and RFLP techniques. Biochemical parameters were measured in a computerized autoanalyzer.

RESULTS

In the patient group, the distribution of the CC, CT, and TT genotypes was 44.8% (n = 13), 37.9% (n = 11), and 17.2% (n = 5), respectively. The frequencies of the C and T alleles were 0.64 and 0.36, respectively. Subjects with the T allele had the highest levels of TC (P <.05) and LDL-C (P <.05); subjects with the CC genotype had the lowest.

CONCLUSIONS

We observed that the MTHFR T allele has an unfavorable effect on serum lipid profile, leading to a rise in the total and LDL cholesterol concentrations. Thus, we believe that MTHFR C allele has a protective effect and MTHFR T allele has a detrimental effect on the serum lipid profile.