Recurrence of hemolytic uremic syndrome after renal transplantation

TMA in Kidney Transplantation

Thrombotic microangiopathy (TMA) is a rare and devastating complication of kidney transplantation, which often leads to graft failure. Posttransplant TMA (PT-TMA) may occur either de novo or as a recurrence of the disease. De novo TMA can be triggered by immunosuppressant drugs, antibody-mediated rejection, viral infections, and ischemia/reperfusion injury in patients with no evidence of the disease before transplantation. Recurrent TMA may occur in the kidney grafts of patients with a history of atypical hemolytic uremic syndrome (aHUS) in the native kidneys. Studies have shown that some patients with aHUS carry genetic abnormalities that affect genes that code for complement regulators (CFH, MCP, CFI) and components (C3 and CFB), whereas in 10% of patients (mostly children), anti-FH autoantibodies have been reported. The incidence of aHUS recurrence is determined by the underlying genetic or acquired complement abnormality. Although treatment of the causative agents is usually the first line of treatment for de novo PT-TMA, this approach might be insufficient. Plasma exchange typically resolves hematologic abnormalities but does not improve kidney function. Targeted complement inhibition is an effective treatment for recurrent TMA and may be effective in de novo PT-TMA as well, but it is necessary to establish which patients can benefit from different therapeutic options and when and how these can be applied.

De Novo and Recurrent Thrombotic Microangiopathy After Renal Transplantation: Current Concepts in Management

Thrombotic microangiopathy is a well-recognized complication of kidney transplantation that leads frequently to allograft failure. This serious outcome can greatly depend on the underlying etiology and on the timing of therapeutic interventions. Thrombotic microangiopathy syndrome may occur with no previous history of thrombotic microangiopathy (that is, de novo thrombotic microangiopathy), mostly due to medica tions or infections. More frequently, it may recur after kidney transplant in patients with endstage renal failure due to atypical hemolytic uremic syndrome. However, for patients with Shiga-toxininduced hemolytic uremic syndrome, particularly pediatric patients, there is a favorable prognosis. A fundamental tool for management of this disease is genetic screening for abnormal mutations; this can recognize the suggested approach of therapy and may determine the outcome of the disease to a large extent. Although patients with complement factor H and I mutations have worse prognosis, other patients with membrane cofactor protein mutations, for example, have a more favorable prognosis. Accordingly, the plan of therapy can be tailored with a better chance of cure. Unfortunately, the successful use of the biological agent eculizumab, an anti-C5 agent, in some of these syndromes is largely impeded by its high cost, which is linked to its use as a life-long therapy. However, newly suggested therapeutic options may ameliorate this drawback.

Thrombotic microangiopathy in a renal allograft: Single-center five-year experience

Thrombotic microangiopathy (TMA) is devastating for renal transplantation (RT) causing graft/ patient loss. We present 5-year experience of TMA in RT in retrospective study of indicated renal allograft biopsies with TMA. Patient-donor demographics and associated histological findings with respect to transplants under tolerance induction protocol (Group 1) were compared with patients transplanted under triple immunosuppression (Group 2). Statistical analysis was performed using IBM SPSS Statistics version 20. Sixty-one (4.1%) of 1520 biopsies [Group 1:17 (1.9%)/882, Group 2:44 (6.9%)/638] revealed TMA. Tacrolimus trough levels were normal. There was no evidence of systemic involvement in any patient. Mean age was 36.8 years with 70.6% males, HLA-match, 2.6/6, and the most common original disease unknown (41.2%) in Group 1, and 35.9 years with 86.4% males, HLA-match, 2.1/6, and the most common original disease unknown (50%) in Group 2. Biopsies were performed at mean 5.1-year posttransplant in Group 1 and 2.3 years in Group 2. Acute TMA constituted 47% Group 1 and 43.2% Group 2 biopsies; of these, antibody-mediated rejections were observed in 58.8%, T-cell mediated rejections in 11.8%, tacrolimus toxicity in 76.5%, and other findings in 35.3% Group 1; and 61.4%, 25%, 50%, and 18.2%, respectively, in Group 2 biopsies. Higher rejection activity scores were more in Group 2. Postbiopsy 1- and 5- year patient survival was 94.1%, 86.9% in Group 1 and 92.1%, 88.3% in Group 2; 1- and 4-year graft survival was 52.9%, 15.9% in Group 1 and 20.3%, 5.4% in Group 2. TMA was poor prognosticator for RT, especially under triple immunosuppression. Antibody- mediated rejection and tacrolimus toxicity were more prone to TMA.

Effect of Immunosuppressive Therapy on the Occurrence of Atypical Hemolytic Uremic Syndrome in Renal Transplant Recipients

Background

Atypical hemolytic uremic syndrome (aHUS), a rare thrombotic microangiopathy, is characterized by hemolytic anemia, thrombocytopenia, and acute renal failure. Caused by genetic mutations in the alternative complement cascade, aHUS often will culminate in end-stage renal disease and occasionally death. Renal transplantation in aHUS patients has been contraindicated in the past due to the recurrence risk, with certain immunosuppressive regimens being commonly attributed. In this study, we analyzed the association between aHUS and immunosuppressive agents so as to offer evidence for the use of certain immunosuppressive regimens in renal transplant recipients.

Material/Methods

Our study is a retrospective analysis using data from the United States Renal Data System from 2004 to 2012. A cohort of renal transplantation patients diagnosed with aHUS were identified to include in the study. The primary endpoint was the determination of aHUS incidence in renal transplant recipients due to various immunosuppressive agents. The secondary endpoints were to check the relationship between the drug type as well as the demographic variables that increase the risk for aHUS.

Results

It was found that there was a higher usage of sirolimus (P=0.015) and corticosteroids (P=0.030) in the aHUS patients compared to patients in other diagnoses group.

Conclusions

There was a higher usage of sirolimus and corticosteroids in renal transplantation patients diagnosed with aHUS. Unfortunately, due to the rarity of this disease, the sample size was small (n=14). Despite the small sample size, this data analysis throws light on the relationship between aHUS and immunosuppressive agents in renal transplant recipients, although we still have much to learn.

Renal Transplant Immunosuppression in Patients With Hemolytic Uremic Syndrome: Four Case Reports

A high rate of recurrence has been described in atypical hemolytic uremic syndrome renal transplant recipients, favored by certain immunosuppressant drugs that can induce complement activation. We present four case series in which three patients were diagnosed pretransplantation and a fourth who had onset in the very early post-transplantation period. The patients received different immunosuppression schedules, and all had improvement after more than 2-years. We suggest the need to stratify the risk of atypical hemolytic uremic syndrome recurrence using genetic studies and the available drugs as the main factors that allow graft survival improvement today.

Managing and preventing atypical hemolytic uremic syndrome recurrence after kidney transplantation

PURPOSE OF REVIEW

Several genetic and acquired abnormalities leading to abnormal activation of the alternative pathway of complement have been identified in patients with atypical hemolytic uremic syndrome (aHUS). The purpose of this review is to shed light on how advances in the understanding of aHUS pathogenesis have impacted on prevention and cure of aHUS recurrence after kidney transplantation.

RECENT FINDINGS

Studies over the past decade have shown that the risk of posttransplant recurrence of aHUS depends on the underlying genetic abnormality. The risk is high in patients with mutations in genes encoding circulating complement proteins and regulators, whereas patients with mutations in membrane cofactor protein generally show good transplant outcome. Given the poor outcome associated with recurrence, isolated renal transplantation had been contraindicated in aHUS patients. Combined kidney-liver transplantation and prophylactic plasma exchange have been used to prevent posttransplant recurrences. More recent data have provided evidence about the efficacy of the anti-C5 monoclonal antibody eculizumab in the prevention and treatment of posttransplant aHUS recurrences.

SUMMARY

This review summarizes recent advances on preventing and managing aHUS recurrence after kidney transplantation and discusses the issues that still need clarification.

Thrombotic microangiopathy in renal allografts: the diagnostic challenge

PURPOSE OF REVIEW

The diagnosis of thrombotic microangiopathy (TMA) is complex and often difficult. This review provides an approach to the diagnosis with emphasis on recent relevant developments.

RECENT FINDINGS

There is increasing evidence that most cases of recurrent TMA in renal allografts are secondary to mutations in genes encoding complement regulatory factors and complement components, such as factor H, factor I, membrane cofactor protein, C3, and others. Genetic work-up for these potential complement abnormalities is now available and recommended. Another important cause for recurrent TMA is the presence of autoantibodies, such as antibodies to factor H and antiphospholipid antibodies. De-novo TMA is much more common than recurrent TMA in renal allografts. De-novo TMA can be secondary to calcineurin inhibitor treatment, mammalian target of rapamycin inhibitor treatment, but frequently also to antibody-mediated rejection and less commonly to infections. Systemic signs of TMA are often absent, and the gold standard for diagnosis is the renal allograft biopsy. Unfortunately, diagnostic criteria for TMA are somewhat subjective, and the biopsy provides limited information regarding the exact underlying cause.

SUMMARY

TMA is a serious complication of renal transplantation, usually with poor outcome. However, with improving understanding of underlying pathogeneses, more effective disease-specific therapeutic interventions can be designed. Appropriate treatment depends on the correct diagnosis, which relies primarily on renal allograft biopsy. Standardization of pathologic criteria and introduction of new molecular testing methods in renal biopsy specimens hopefully will improve diagnostic accuracy.

Update on hemolytic uremic syndrome: Diagnostic and therapeutic recommendations

Hemolytic uremic syndrome (HUS) is a rare disease. In this work the authors review the recent findings on HUS, considering the different etiologic and pathogenetic classifications. New findings in genetics and, in particular, mutations of genes that encode the complement-regulatory proteins have improved our understanding of atypical HUS. Similarly, the complement proteins are clearly involved in all types of thrombotic microangiopathy: typical HUS, atypical HUS and thrombotic thrombocytopenic purpura (TTP). Furthermore, several secondary HUS appear to be related to abnormalities in complement genes in predisposed patients. The authors highlight the therapeutic aspects of this rare disease, examining both "traditional therapy" (including plasma therapy, kidney and kidney-liver transplantation) and "new therapies". The latter include anti-Shiga-toxin antibodies and anti-C5 monoclonal antibody "eculizumab". Eculizumab has been recently launched for the treatment of the atypical HUS, but it appears to be effective in the treatment of typical HUS and in TTP. Future therapies are in phases I and II. They include anti-C5 antibodies, which are more purified, less immunogenic and absorbed orally and, anti-C3 antibodies, which are more powerful, but potentially less safe. Additionally, infusions of recombinant complement-regulatory proteins are a potential future therapy.

Successful long-term outcome after renal transplantation in a patient with atypical haemolytic uremic syndrome with combined membrane cofactor protein CD46 and complement factor I mutations

BACKGROUND

Atypical haemolytic uremic syndrome (aHUS) is often associated with a high risk of disease recurrence and subsequent graft loss after isolated renal transplantation. Evidence-based recommendations for a mutation-based management after renal transplantation in aHUS caused by a combined mutation with complement factor I (CFI) and membrane cofactor protein CD46 (MCP) are limited.

CASE-DIAGNOSIS/TREATMENT

We describe a 9-year-old boy with a first manifestation of aHUS at the age of 9 months carrying combined heterozygous mutations in the CFI and MCP genes. At the age of 5 years, he underwent isolated cadaveric renal transplantation. Fresh frozen plasma was administered during and after transplantation, tapered and finally stopped after 3 years.

CONCLUSIONS

During the 5-year follow-up after transplantation there have been no signs of aHUS recurrence and graft function has remained good. The combination of heterozygous MCP and CFI mutations with aHUS might have a positive impact on the post-transplant course, possibly predicting a lower risk of aHUS recurrence after an isolated cadaveric renal transplantation.

Changing strategies for organ transplantation in atypical haemolytic uraemic syndrome: a tertiary case series

We present three cases of organ transplantation for atypical haemolytic uraemic syndrome secondary to complement factor H mutation: one isolated renal transplant; one previously reported isolated liver transplant; and one combined liver and kidney transplant. All three patients were treated prior to the licensing of eculizumab for this condition, and all have had favourable outcomes with maintenance of graft function for years following transplantation. We discuss the evolution of transplantation therapy for aHUS over the last two decades. Transplantation decision-making in aHUS has evolved over this time with expanding knowledge of pathophysiology and genetics, alongside refined plasma exchange and anticoagulation protocols and improved centre experience. Our cases demonstrate how individual patient factors within this heterogeneous condition also underlie transplantation decisions and outcomes. Whilst our cases demonstrate that transplantation in aHUS can be a successful long-term treatment providing good quality of life, worldwide experience has proven that most curative treatment for aHUS strategies represents significant risks. Whether new pharmacotherapies such as eculizumab will alter this risk is yet to be determined.

Combined complement gene mutations in atypical hemolytic uremic syndrome influence clinical phenotype

Several abnormalities in complement genes reportedly contribute to atypical hemolytic uremic syndrome (aHUS), but incomplete penetrance suggests that additional factors are necessary for the disease to manifest. Here, we sought to describe genotype-phenotype correlations among patients with combined mutations, defined as mutations in more than one complement gene. We screened 795 patients with aHUS and identified single mutations in 41% and combined mutations in 3%. Only 8%-10% of patients with mutations in CFH, C3, or CFB had combined mutations, whereas approximately 25% of patients with mutations in MCP or CFI had combined mutations. The concomitant presence of CFH and MCP risk haplotypes significantly increased disease penetrance in combined mutated carriers, with 73% penetrance among carriers with two risk haplotypes compared with 36% penetrance among carriers with zero or one risk haplotype. Among patients with CFH or CFI mutations, the presence of mutations in other genes did not modify prognosis; in contrast, 50% of patients with combined MCP mutation developed end stage renal failure within 3 years from onset compared with 19% of patients with an isolated MCP mutation. Patients with combined mutations achieved remission with plasma treatment similar to patients with single mutations. Kidney transplant outcomes were worse, however, for patients with combined MCP mutation compared with an isolated MCP mutation. In summary, these data suggest that genotyping for the risk haplotypes in CFH and MCP may help predict the risk of developing aHUS in unaffected carriers of mutations. Furthermore, screening patients with aHUS for all known disease-associated genes may inform decisions about kidney transplantation.

Thrombotic microangiopathy and associated renal disorders

Thrombotic microangiopathy (TMA) is a pathological process involving thrombocytopenia, microangiopathic haemolytic anaemia and microvascular occlusion. TMA is common to haemolytic uraemic syndrome (HUS) associated with shiga toxin or invasive pneumococcal infection, atypical HUS (aHUS), thrombotic thrombocytopenic purpura (TTP) and other disorders including malignant hypertension. HUS complicating infection with shiga toxin-producing Escherichia coli (STEC) is a significant cause of acute renal failure in children worldwide, occurring sporadically or in epidemics. Studies in aHUS have revealed genetic and acquired factors leading to dysregulation of the alternative complement pathway. TTP has been linked to reduced activity of the ADAMTS13 cleaving protease (typically with an autoantibody to ADAMTS13) with consequent disruption of von Willebrand factor multimer processing. However, the convergence of pathogenic pathways and clinical overlap create diagnostic uncertainty, especially at initial presentation. Furthermore, recent developments are challenging established management protocols. This review addresses the current understanding of molecular mechanisms underlying TMA, relating these to clinical presentation with an emphasis on renal manifestations. A diagnostic and therapeutic approach is presented, based on international guidelines, disease registries and published trials. Early treatment remains largely empirical, consisting of plasma replacement/exchange with the exception of childhood STEC-HUS or pneumococcal sepsis. Emerging therapies such as the complement C5 inhibitor eculizumab for aHUS and rituximab for TTP are discussed, as is renal transplantation for those patients who become dialysis-dependent as a result of aHUS.

Thrombotic microangiopathy after kidney transplantation

Thrombotic microangiopathy (TMA) is a severe complication of kidney transplantation that often causes graft failure. TMA may occur de novo, often triggered by immunosuppressive drugs and acute antibody-mediated rejection, or recur in patients with previous history of hemolytic uremic syndrome (HUS). Recurrent TMA is very rare in patients who had developed end-stage renal failure following HUS caused by Shiga-toxin producing E. scherichia coli, whereas disease recurrence is common in patients with atypical HUS (aHUS). The underlying genetic defect greatly impacts the risk of posttransplant recurrence in aHUS. Indeed recurrence is almost the rule in patients with mutations in genes encoding factor H or factor I, whereas patients with a mutation in membrane-cofactor-protein gene have a good transplant outcome. Prophylactic and therapeutic options for posttransplant TMA, including plasma therapy, combined kidney and liver transplantation and targeted complement inhibitors are discussed in this review.

Successful renal transplantation in a patient with atypical hemolytic uremic syndrome carrying mutations in both factor I and MCP

Kidney transplantation in patients with atypical hemolytic uremic syndrome (aHUS) carrying mutations in the soluble complement regulators factor H (CFH) or factor I (CFI) is associated with elevated risk of disease recurrence and almost certain graft loss. In contrast, recurrence is unusual in patients with mutations in the membrane-associated complement regulator membrane cofactor protein (MCP) (CD46). Therefore, a panel of experts recently recommended the combined liver-kidney transplantation to minimize aHUS recurrence in patients with mutations in CFH or CFI. There was, however, very limited information regarding transplantation in patients carrying mutations in both soluble and membrane-associated complement regulators to support a recommendation. Here, we report the case of an aHUS patient with a heterozygous mutation in both CFI and MCP who received an isolated kidney transplant expressing normal MCP levels. Critically, the patient suffered from a severe antibody-mediated rejection that was successfully treated with plasmapheresis and IvIgG. Most important, despite the complement activation in the allograft, there was no evidence of thrombotic microangiopathy, suggesting that the normal MCP levels in the grafted kidney were sufficient to prevent the aHUS recurrence. Our results suggest that isolated kidney transplantation may be a good first option for care in aHUS patients carrying CFI/MCP combined heterozygous mutations.

Liver-kidney transplantation to cure atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome is often associated with mutations in genes encoding complement regulatory proteins and secondary disorders of complement regulation. Progression to kidney failure and recurrence with graft loss after kidney transplantation are frequent. The most common mutation is in the gene encoding complement factor H. Combined liver-kidney transplantation may correct this complement abnormality and prevent recurrence when the defect involves genes encoding circulating proteins that are synthesized in the liver, such as factor H or I. Good outcomes have been reported when surgery is associated with intensified plasma therapy. A consensus conference to establish treatment guidelines for atypical hemolytic uremic syndrome was held in Bergamo in December 2007. The recommendations in this article are the result of combined clinical experience, shared research expertise, and a review of the literature and registry information. This statement defines groups in which isolated kidney transplantation is extremely unlikely to be successful and a combined liver-kidney transplant is recommended and also defines those for whom kidney transplant remains a viable option. Although combined liver-kidney or isolated liver transplantation is the preferred therapeutic option in many cases, the gravity of risk associated with the procedure has not been eliminated completely, and assessment of risk and benefit requires careful and individual attention.