Fulminant recurrence of atypical hemolytic uremic syndrome during a calcineurin inhibitor-free immunosuppression regimen

Favorable four-yr outcome after renal transplantation in a patient with complement factor H antibody and CFHR1/CFHR3 gene mutation-associated HUS

aHUS is a clinical challenge for successful renal transplantation.

CASE REPORT

A 14-yr-old girl lost her kidneys at the age of 7, due to CFH antibodies and CFH-related protein (CFHR1/CFHR3) homozygous deletion-associated aHUS. CFH, CFI, and MCP gene mutations were excluded. The patient was a candidate for renal transplantation despite persistent presence of CFH antibodies (up to 539 AU/mL). Treatment with MMF, IVIG, and repeated PF (n = 8) was introduced while being placed on urgent waiting list. Three years after aHUS onset, the patient underwent the deceased donor renal transplantation "under cover" of PF, as PF was performed directly prior to surgery and, then, PFs were repeated up to overall 14 sessions. Quadruple immunosuppression (basiliximab + tacrolimus + MMF + prednisolone) was used. Moderate symptoms of aHUS (hemolysis, low platelets, and low C3) were present within first seven days post-transplant and then normalized with PF therapy. The patient remained stable during four yr of further follow-up after transplantation.

CONCLUSION

Specific pre- and post-transplant management allowed successful renal transplantation in a CFH antibody-positive patient.

Eculizumab induces long-term remission in recurrent post-transplant HUS associated with C3 gene mutation

A 15-year-old male patient developed atypical hemolytic uremic syndrome (aHUS) at 16 months of age leading to end-stage renal disease. The family history was suggestive of autosomal dominant aHUS, and he was more recently found to have a C3 heterozygous gene mutation (1835C>T mutation in exon 14, which determines the amino-acidic substitution R570W) with no other complement abnormalities. He had two renal transplants, the first at 2.5 years, and the second at 8 years of age, but allograft dysfunction developed in both transplants leading to graft failure due to recurrent HUS at 5 years and 18 months post-transplantation respectively. At 15 years of age he received a third transplant from a deceased donor with pre-emptive plasmapheresis. He had immediate graft function and nadir serum creatinine was 1.3-1.4 mg/dl. Severe allograft dysfunction and hypertension developed 2 months after transplantation following influenza infection. Renal allograft biopsy showed thrombotic microangiopathy. He received plasmapheresis followed by eculizumab therapy. Allograft function returned to baseline 3 weeks after starting therapy, and post-treatment allograft biopsies showed improvement in thrombotic microangiopathy. He continues to receive eculizumab every 2 weeks with stable graft function 13 months after transplantation.

Recurrence of HUS due to CD46/MCP mutation after renal transplantation: a role for endothelial microchimerism

Mutations in the gene of the membrane cofactor protein (MCP/CD46), a complement regulatory protein, were recently described as a cause of hemolytic uremic syndrome (HUS). MCP is a transmembrane glycoprotein expressed in kidneys; therefore, the transplantation of a normal kidney should not be complicated by HUS recurrence. However, we report the case of a 32-year-old woman with an MCP mutation who developed a recurrence of HUS after renal transplantation. We found that she had vascular microchimerism of endothelial cells. We suggest that recurrence may be favored by vascular microchimerism, in which the mutated protein is produced in the in the kidney graft by endothelial cells originating from recipient.

Diagnosis of de novo localized thrombotic microangiopathy by surveillance biopsy

Thrombotic microangiopathy has been reported in association with calcineurin inhibitors and less frequently with sirolimus in renal transplant patients. The diagnosis of thrombotic microangiopathy is typically made by diagnostic biopsy in the setting of allograft dysfunction. The finding of thrombotic microangiopathy on surveillance biopsy without a significant elevation of baseline serum creatinine is unusual. The optimal treatment of this disorder remains controversial. Treatment strategies have included dose adjustment, drug substitution, plasmapheresis, and intravenous immunoglobulin G. We report a case of de novo thrombotic microangiopathy diagnosed by surveillance biopsy in a patient without hematologic abnormalities or elevated serum creatinine. This patient had resolution of the renal lesion following conversion from tacrolimus to sirolimus-based immunosuppression.

Renal transplantation in HUS patients with disorders of complement regulation

Haemolytic uraemic syndrome (HUS) is the primary diagnosis of 4.5% of children on chronic renal replacement therapy. Approximately 5% of all HUS cases have an "atypical" or recurrent course. Atypical HUS is an inadequate term that applies to a heterogeneous group of conditions. We describe this group as non-diarrhoeal (D-) ), non-EHEC (EHEC - ) HUS. Patients in the non-diarrhoeal, non-EHEC, relapsing group are much more likely to exhibit severe hypertension, histological findings of arterial as well as arteriolar disease, chronic and end-stage renal failure. In general, these patients have an alarmingly high risk of graft loss from disease recurrence or thrombosis ranging from 60-100%. Family history is crucial, and where family members have relapsing disease, transplantation is a very high risk procedure (recurrence 100%). Patients with (D-)HUS need very careful consideration before transplantation, including molecular investigation of complement regulators (and von Willebrandt protease (ADAMTS13) activity, although this goes beyond the scope of this review). Guidelines are accessible under http://www.espn.ucwm.ac.uk . On no account should live related donation take place unless the risks of graft loss are understood. International collaboration to identify safer ways of transplanting these challenging patients is urgently needed.

Favorable long-term outcome after liver-kidney transplant for recurrent hemolytic uremic syndrome associated with a factor H mutation

A male child initially presented with atypical hemolytic uremic syndrome (HUS) at the age of 4 months and progressed within weeks to end stage renal disease (ESRD). At the age of 2 years he received a live-related kidney transplant from his mother, which, despite initial good function, was lost to recurrent disease after 2 weeks. Complement factor H analysis showed low serum levels and the presence of two mutations on different alleles (c.2918G > A, Cys973Tyr and c.3590T > C, Val1197Ala). His survival on dialysis was at risk because of access failure and recurrent bacteremic episodes. Therefore, at the age of 5 years he received a combined liver-kidney transplant with pre-operative plasma exchange. Initial function of both grafts was excellent and this has been maintained for over 2 years. This report suggests that despite setbacks in previous experience, combined liver-kidney transplantation offers the prospect of a favorable long-term outcome for patients with HUS associated with complement factor H mutations.

A classification of hemolytic uremic syndrome and thrombotic thrombocytopenic purpura and related disorders

The diagnostic terms hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) are based on historical and overlapping clinical descriptions. Advances in understanding some of the causes of the syndrome now permit many patients to be classified according to etiology. The increased precision of a diagnosis based on causation is important for considering logical approaches to treatment and prognosis. It is also essential for research. We propose a classification that accommodates both a current understanding of causation (level 1) and clinical association in cases for whom cause of disease is unclear (level 2). We tested the classification in a pediatric disease registry of HUS. The revised classification is a stimulus to comprehensive investigation of all cases of HUS and TTP and is expected to increase the proportion of cases in whom a level 1 etiological diagnosis is confirmed.

Sirolimus for solid organ transplantation in children

Sirolimus represents a major advancement in the field of solid organ transplantation and is being used as a rescue agent for acute and chronic rejection as well as for primary immunosuppression with good graft outcome. Although initial studies with sirolimus were in adults, now significant data have accumulated on the role of sirolimus in pediatric solid organ transplantation. This article reviews the current status of sirolimus in pediatric transplantation.

Current status of kidney transplant: update 2003

Pediatric transplantation has seen remarkable advances over the past two decades with reduced morbidity and mortality, reduced rejection rates, and improved long-term patient and allograft survival. Infants currently have short-term patient and allograft survival rates better than any other age group; short-term allograft survival rates in CD recipients are equal to those in LD recipients. With decreased rejection, long-term allograft survival is improving dramatically. Transplantation allows for much reduced risks and improved metabolic status, growth and development, and more normal social interactions. The future of transplantation continues to be exciting, with opportunities for reduced immunosuppressive medications and their side effects, and the elusive goal of transplantation tolerance seems within reach.

The risk of recurrence of hemolytic uremic syndrome after renal transplantation in children

We reviewed the literature to analyze the risk of recurrence of hemolytic uremic syndrome (HUS) after renal transplantation in children. Among 118 children transplanted after post-diarrheal (D+) HUS, 1 (0.8%) had recurrence with graft loss. Among 63 children transplanted after HUS not associated with a prodrome of diarrhea (D-) of unknown mechanism, 13 (21%) had recurrence with graft loss. Of 11 patients with HUS associated with factor H deficiency who were transplanted, 5 lost the graft because of recurrence. Of 7 patients with HUS associated with normal factor H concentration but mutations in factor H gene who were transplanted, probably 2 had recurrence. Three patients with HUS associated with low serum C3, but no factor H deficiency or mutation lost their graft because of recurrence. The risk of recurrence in the autosomal recessive forms of HUS of unknown mechanism is not documented in children, but is around 60% in adults. A similar risk has been reported in the autosomal dominant forms. The only transplant patient with a constitutional deficiency of von Willebrand factor-cleaving protease had recurrence. Further efforts to document the post-transplant course of patients with D- HUS and progress in the understanding of the mechanisms and genetics of the disease are needed to allow more accurate prediction of the recurrence risk and to define therapeutic approaches.

Sirolimus-induced thrombotic microangiopathy in a renal transplant recipient

A rare but well-documented serious adverse reaction to the administration of the calcineurin inhibitors tacrolimus and cyclosporine in renal transplant recipients is the development of medication-induced thrombotic microangiopathy. The recently introduced immunosuppressive medication sirolimus has a very similar molecular structure to tacrolimus and also binds to the same intracellular proteins. Despite these similarities with tacrolimus, sirolimus has a different side-effect profile and reportedly lacks documented specific renal toxicity. This is a case report of the isolated administration of sirolimus without a concomitant calcineurin inhibitor being associated with the development of renal transplant biopsy-proven thrombotic microangiopathy. The patient is a 47-year-old African-American woman whose primary cause of renal failure was not thrombotic micrangiopathy, and she received a 5-antigen mismatched cadaveric renal transplant. Because of preexisting nephrosclerosis in the renal transplant, this patient was never administered a calcineurin inhibitor but was always maintained on sirolimus. With recent animal data showing that sirolmus can be nephrotoxic in a renal ischemic-reperfusion model (similar to what happens with a renal transplant), the authors speculate on a mechanism for this adverse reaction.