Monitoring of complement activation biomarkers and eculizumab in complement-mediated renal disorders

Various complement-mediated renal disorders are treated currently with the complement inhibitor eculizumab. By blocking the cleavage of C5, this monoclonal antibody prevents cell damage caused by complement-mediated inflammation. We included 23 patients with atypical haemolytic uraemic syndrome (aHUS, n = 12), C3 glomerulopathies (C3G, n = 9) and acute antibody-mediated renal graft rejection (AMR, n = 2), treated with eculizumab in 12 hospitals in Germany. We explored the course of complement activation biomarkers and the benefit of therapeutic drug monitoring of eculizumab. Complement activation was assessed by analysing the haemolytic complement function of the classical (CH50) and the alternative pathway (APH50), C3 and the activation products C3d, C5a and sC5b-9 prior to, 3 and 6 months after eculizumab treatment. Eculizumab concentrations were determined by a newly established specific enzyme-linked immunosorbent assay (ELISA). Serum eculizumab concentrations up to 1082 μg/ml point to drug accumulation, especially in paediatric patients. Loss of the therapeutic antibody via urine with concentrations up to 56 μg/ml correlated with proteinuria. In aHUS patients, effective complement inhibition was demonstrated by significant reductions of CH50, APH50, C3d and sC5b-9 levels, whereas C5a levels were only reduced significantly after 6 months' treatment. C3G patients presented increased C3d and consistently low C3 levels, reflecting ongoing complement activation and consumption at the C3 level, despite eculizumab treatment. A comprehensive complement analysis together with drug monitoring is required to distinguish mode of complement activation and efficacy of eculizumab treatment in distinct renal disorders. Accumulation of the anti-C5 antibody points to the need for a patient-orientated tailored therapy.

Cell-free plasma hemoglobin removal by dialyzers with various permeability profiles

The release of hemoglobin from mechanically stressed erythrocytes into plasma is a general side effect of extracorporeal therapies, such as extracorporeal membrane oxygenation or hemodialysis. In many reported cases dialysis patients showed elevated cell-free plasma hemoglobin (CPH) levels which are associated with pathophysiological effects. In this in vitro study, the CPH clearance capacity of various filters with different permeability profiles was measured. Simulated dialysis treatments were conducted and clearance was calculated from variations in CPH concentrations over time by measuring plasma absorbance at 405 nm. Conventional high-flux filters exhibited no detectable clearance of CPH. High-flux filters with extended permeability exhibited clearances between 5.8 ± 1.2 and 12.7 ± 1.7 ml/min when tested with plasma and between 5.8 ± 1.2 and 11.3 ± 1.6 ml/min when tested with whole blood. septeX high-cutoff filters had clearances between 13.8 ± 1.8 and 15.5 ± 1.7 ml/min when tested with plasma and of 22.6 ± 2.9 ml/min when tested with whole blood. This study demonstrated that filters with extended permeability and the septeX filter enable CPH removal when used as in chronic and acute settings.

Single-stage surgical approach in complicated paediatric ureteral duplication: surgical and functional outcome

PURPOSE

Surgical approach to children with complicated ureteral duplication is discussed controversially. Our aim was to determine the outcome of children with complicated renal duplication undergoing a single-stage surgical approach with laparoscopic partial nephrectomy and open bladder reconstruction.

METHODS

Data of patients from 2004 to 2008 were investigated retrospectively. Outcome was analyzed in terms of postoperative course, renal function, urinary tract infection and functional voiding.

RESULTS

Thirteen patients were treated with laparoscopic partial nephrectomy and reconstruction of the lower urinary tract in a single-stage approach. Median age at operation was 15 months (2-63 m). One girl had a renal triplication. 7/13 patients presented with an ectopic ureterocele, two with an ectopic ureter, severe vesicoureteral reflux occurred in 6 patients. All patients had non-functioning renal moieties. Mean operative time was 239 min (129-309; SD 50). One re-operation was necessary 4 years after primary surgery due to a pole remnant. All patients had uneventful recoveries without evidence of recurrent UTI. Postoperative 99mTc-MAG3 scans showed no significant reduction of partial renal function (p = 0.4), and no signs of obstruction (p = 0.188). During a median follow-up of 60 months (49-86), dysfunctional voiding occurred in one patient.

CONCLUSIONS

In children with complicated ureteral duplication a definitive single-stage procedure is feasible and shows excellent functional results.

Single kidney and ureteral atresia in a newborn girl: a treatment concept

OBJECTIVE

To demonstrate a rare case of urological pathology, we report a combination of a single kidney and ureteral atresia. The treatment concept and outcome are outlined.

PATIENT AND METHOD

Antenatal ultrasound had revealed urinary ascites which lead to caesarean section in the 34th gestational week. Persisting anuria was confirmed postnatally and peritoneal dialysis started on the second day of life. Subsequent laparotomy revealed ureteral atresia after 3 cm of patent ureter. We created an ileum conduit after discussing various other therapeutic options.

RESULT AND CONCLUSION

A follow up of 12 months has shown steady function of the stoma with stable renal parameters. An ileal conduit represents a good option if high drainage is necessary in early childhood.

Prophylactic eculizumab prior to kidney transplantation for atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome (aHUS) in childhood is a rare disease associated with high morbidity and mortality. Most cases progress to end-stage renal failure. In approximately 50% of affected patients, mutations in genes encoding complement proteins are causative of the impairment in the regulation of the complement alternative pathway. This leads to deficient host cell protection and inappropriate complement activation on platelets and endothelial cells, particularly in the kidneys. Complement factor H (FH) heterozygosity induces unregulated activation of the membrane attack complex (MAC) C5b-9. Present therapeutic strategies for aHUS include lifelong plasmapheresis and renal dialysis. Unfortunately, kidney transplantation is frequently an unsatisfactory intervention due to the high rate of post-transplantation HUS recurrence, particularly in patients with FH mutation. Combined liver-kidney transplantation is also associated with poor outcome, mostly as a result of premature liver failure secondary to uncontrolled complement activation. Eculizumab is a complement C5 antibody that inhibits complement factor 5a (C5a) and the formation of the MAC. Thus, this antibody may be a promising new agent for patients with an aHUS undergoing kidney transplantation. We present the first case of a young patient with aHUS who received eculizumab as prophylactic treatment prior to a successful kidney transplantation.

Suicidal death of erythrocytes in recurrent hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is characterized by hemolytic anemia with fragmented erythrocytes, thrombocytopenia, and acute renal failure. Lack of complement inactivating factor H predisposes to the development of atypical HUS. Little is known about mechanisms linking complement activation with loss of erythrocyte integrity during HUS. Recent studies disclosed that increased cytosolic Ca2+ activity and cellular ceramide trigger programmed erythrocyte death or eryptosis, characterized by cell shrinkage and phosphatidylserine exposure at the erythrocyte surface. In the present study, we investigated whether eryptosis occurs during the course of HUS. To this end, erythrocytes from healthy volunteers were exposed to plasma from a patient with severe idiopathic recurrent HUS secondary to factor H depletion. Phosphatidylserine exposure (Annexin binding), cell volume (forward scatter), cytosolic Ca2+ activity (Fluo3 fluorescence), and ceramide formation [anti-ceramide antibody and enzymatic (diacylgycerol kinase) analysis] were determined. Exposure of erythrocytes to plasma from the patient, but not to plasma from healthy individuals, triggered Annexin binding. The effect of plasma on erythrocyte Annexin binding was abolished by plasmapheresis or filtration at 30 kDa. It was paralleled by formation of ceramide and increase of cytosolic Ca2+ activity. Enhanced Annexin binding of erythrocytes from healthy individuals was observed after exposure to plasma from three other patients with HUS. The proeryptotic effect of patient plasma was mimicked by exposure to the Ca2+ ionophore ionomycin, and eryptosis was potentiated in the presence of cell membrane-permeable C6-ceramide. Furthermore, in vitro complement activation similarly triggered erythrocyte phosphatidylserine exposure, an effect which was blunted by the addition of factor H. In conclusion, our present observations disclose a novel, pathophysiological, factor-H dependent mechanism leading to injury of erythrocytes during the course of hemolytic uremic syndrome.

[The treatment with levamisole of frequently recurring steroid-sensitive idiopathic nephrotic syndrome in children]

BACKGROUND AND OBJECTIVE

The treatment of frequently relapsing steroid-sensitive nephrotic syndrome in children with established immunosuppressive drugs (steroids, cyclophosphamide, cyclosporin A) sometimes presents problems because of the expected incidence of side effects. Stimulation of the immune system with the anthelminthic drug levamisole in this disease has been documented. Aim of this study was to assess in a prospective but uncontrolled series of observations its value and side effects.

PATIENTS AND METHODS

25 patients (15 boys, ten girls; median age 10 [3.5-22] years) were given levamisole, 2 mg/kg/48 h. Before this treatment was started eight of the children/adolescents (32%) had frequent relapses and 17 (68%) had become steroid-dependent. Treatment was started during steroid-induced remission and continued for 3-24 (median 6) month, while steroids were discontinued after four weeks.

RESULTS

Relapse frequency per patient month was reduced from a mean of 0.5 (0.33-0.83) before to 0.31 (0-0.67) during levamisole administration (P < 0.001). In 12 patients (48%) no or considerably fewer relapses were observed. Patients with exclusively frequent relapses responded to levamisole better than those with steroid dependence (7/8 [87.5%] vs. 5/18 [27.7%], P = 0.01). Side effects were reversible leukopenia in two patients and nonspecific skin rash as well as epigastric pain in one patient.

CONCLUSION

Levamisole is an efficacious addition or alternative, with a low incidence of side effects, in the treatment of frequently relapsing nephrotic syndrome, particularly so in yet steroid-dependent patients.

[Bilharziasis as the etiology in hematuria and proteinuria in childhood]

Haematuria and proteinuria are important symptoms of primary and secondary nephropathies. We report three african children presenting to our center in whom infection with S. haematobium resulted in haematuria and proteinuria. The third patient concomitantly suffered from steroid-sensitive relapsing nephrotic syndrome with the histological features of focal and segmental glomerulo-sclerosis. The diagnosis was in all cases established by light microscopy and urinary symptoms improved after treatment with praziquantel. In the third patients long term remission of the nephrotic syndrome could be maintained after 4 doses of praziquantel for recurrent bladder symptoms. We conclude that bilharziosis must be considered in the differential diagnosis of children with haeamturia and proteinuria even in Europe. The diagnosis can be established easily by light microscopy and an effective and low-risk treatment (with Praziquantel) can be offered.

[Value of lymphography, computer tomography and ultrasound in the diagnosis of infradiaphragmatic malignant lymphomas in children]

25 children with Hodgkin's disease and 6 children with Non-Hodgkin-lymphoma were reviewed in order to compare the diagnostic value of lymphography, CT and sonography. As compared with staging-laparotomy, sensitivity for the detection of lymph node involvement was 78% for lymphography, 33% for CT and 57% for the ultrasound examination. Specifity was 55%, 88%, and 83% respectively. Undetected involvement of splenic and liver hilar lymph nodes, unspecific lymphadenitis and fluid-filled bowl loops caused most of the false negative and false positive findings. In 10 children histological examination showed splenic involvement. No splenic lesion was seen by CT in 7 of these children. Splenic disease could be clearly identified by ultrasound in only one child. Although children with lymph node involvement had always splenic manifestations of malignant lymphomatous disease it is concluded that staging laparotomy is an indispensable tool in diagnosing malignant lymphoma. Lymphography should not be abandoned with children. It should be used in combination with either CT or ultrasound examination.

[Torsion of a wandering spleen]

The torsion of an ectopic (= wandering) spleen is a rare entity especially in children. Clinically it presents either with signs of an "acute abdomen" or as a fairly painful abdominal "tumor" of the chronic recurrent type. Ultrasonography, arteriography, and additional scintigraphy in special cases are of greatest value in the preoperative diagnostic management. Splenopexy, sometimes after resecting parts of a very enlarged organ, is the therapy of choice. The complete exstirpation of the ectopic spleen should be reserved only for exceptional cases. By presenting a case report, the etiologic factors, the clinical signs, the diagnostic steps, the differential diagnostic considerations as well as the mode of therapy for this rare disease are described and discussed.

[Results and specific problems in unrestricted indications for kidney transplantation in children]

In Hamburg 22 children had 33 renal transplantations in the time from 1976 till 1982. 58% of all children in this area with end-stage renal disease have now a functioning graft compared to only 11% of the adult patients. This is the result of preferred transplantation in children whenever possible. Retransplantation was more frequent in children (32%) than in adults (19%). 5 years function rate of renal allografts is significantly worse in children than in adults. Growth and degree of rehabilitation are described in 12 pediatric renal allograft recipients who survived with a functioning graft for at least 3 years. Good rehabilitation as indicated by attendance of school and employment was reached in 83% of these patients. Different growth patterns occurred. Clinical factors associated with growth performance include graft function and age at the time of transplantation.