Successful living-related renal transplantation in a patient with factor H antibody-associated atypical hemolytic uremic syndrome

Early relapse rate determines further relapse risk: results of a 5-year follow-up study on pediatric CFH-Ab HUS

BACKGROUND

The complement factor H antibody (CFH-Ab)-associated hemolytic uremic syndrome (HUS) forms a distinct subgroup within the complement-mediated HUS disease spectrum. The autoimmune nature of this HUS subgroup implies the potential benefit of a targeted immunosuppressive therapy. Data on long-term outcome are scarce.

METHODS

This observational study evaluates the clinical outcome of 19 pediatric CFH-Ab HUS patients from disease onset until their 5-year follow-up.

RESULTS

All but one relapse occurred during the first 2 years, and patients who had no relapse within the first 6 months were relapse-free until the end of the observation period. Kidney function at disease onset determines long-term kidney function: all individuals with normal kidney function at disease onset had normal kidney function after 5 years, and all patients with reduced kidney function at onset had impaired kidney function at the last follow-up. Level of CFH-Ab titer at disease onset was not correlated with a higher risk of recurrences or worse long-term outcome after 5 years. Resolution of CFH-Ab titers after 5 years was common.

CONCLUSIONS

CFH-Ab HUS patients have a varied overall long-term course. Early relapses are common, making close surveillance during the first years essential, regardless of the initial CFH-Ab titer.

The choice between deceased- vs living-donor renal transplantation in children: Analysis of data from a Belgian tertiary center

Pediatric renal transplantation with a living donor (LD) has superior outcome, but there is a paucity of studies analyzing the reasons for not undertaking living donation in West-European countries. The aim of this study was to retrospectively review the choice of donor source in our center. We also aimed to identify factors which prevented transplantation with a LD. This retrospective study was performed including children aged 2-19 years who underwent kidney transplantation (KT) at the Ghent University Hospital between 1996 and 2016. Relevant data were collected from medical files to identify the main medical, psychological, and socio-economic factors influencing the choice of the donor source. There were 48 patients (boys n = 33) who underwent KT. Thirty-nine patients received a deceased donor (DD) kidney and nine patients received a LD kidney. Sixteen of 48 transplantations were preemptive. The reasons for DD KT included socio-economic factors such as single caregiver families, one or both parents with a criminal record or convictions and religious or cultural constraints (n = 15), medical considerations (n = 13), refusal of the close relatives/parents to donate (n = 7), and acceptance of an organ from a DD while prospective donor was undergoing medical screening (n = 4). The low incidence of living kidney donation can be explained by socio-economic and medical factors. Refusal to donate is a potentially modifiable factor and strategies aimed at education and guidance of the families might contribute to a higher incidence of living donation in our setting.

Factor H autoantibody is associated with atypical hemolytic uremic syndrome in children in the United Kingdom and Ireland

Factor H autoantibodies can impair complement regulation, resulting in atypical hemolytic uremic syndrome, predominantly in childhood. There are no trials investigating treatment, and clinical practice is only informed by retrospective cohort analysis. Here we examined 175 children presenting with atypical hemolytic uremic syndrome in the United Kingdom and Ireland for factor H autoantibodies that included 17 children with titers above the international standard. Of the 17, seven had a concomitant rare genetic variant in a gene encoding a complement pathway component or regulator. Two children received supportive treatment; both developed established renal failure. Plasma exchange was associated with a poor rate of renal recovery in seven of 11 treated. Six patients treated with eculizumab recovered renal function. Contrary to global practice, immunosuppressive therapy to prevent relapse in plasma exchange-treated patients was not adopted due to concerns over treatment-associated complications. Without immunosuppression, the relapse rate was high (five of seven). However, reintroduction of treatment resulted in recovery of renal function. All patients treated with eculizumab achieved sustained remission. Five patients received renal transplants without specific factor H autoantibody-targeted treatment with recurrence in one who also had a functionally significant CFI mutation. Thus, our current practice is to initiate eculizumab therapy for treatment of factor H autoantibody-mediated atypical hemolytic uremic syndrome rather than plasma exchange with or without immunosuppression. Based on this retrospective analysis we see no suggestion of inferior treatment, albeit the strength of our conclusions is limited by the small sample size.

Anti-complement-factor H-associated glomerulopathies

Atypical haemolytic uraemic syndrome (aHUS), an important cause of acute kidney injury, is characterized by dysregulation of the complement pathway, frequent need for dialysis, and progression to end-stage renal disease. Autoantibodies against complement factor H (FH), the main plasma regulatory protein of the alternative pathway of the complement system, account for a considerable proportion of children with aHUS. The autoantibodies are usually associated with the occurrence of a homozygous deletion in the genes encoding the FH-related proteins FHR1 and FHR3. High levels of autoantibodies, noted at the onset of disease and during relapses, induce functional deficiency of FH, whereas their decline, in response to plasma exchanges and/or immunosuppressive therapy, is associated with disease remission. Management with plasma exchange and immunosuppression is remarkably effective in inducing and maintaining remission in aHUS associated with FH autoantibodies, whereas terminal complement blockade with eculizumab is considered the most effective therapy in other forms of aHUS. Anti-FH autoantibodies are also detected in a small proportion of patients with C3 glomerulopathies, which are characterized by chronic glomerular injury mediated by activation of the alternative complement pathway and predominant C3 deposits on renal histology.