[Immunity and immunosuppression in childhood idiopathic nephrotic syndrome]

[Cyclophosphamide in idiopathic nephrotic syndrome: Outcome and outlook]

INTRODUCTION

Cyclophosphamide (CYP) has been used for over 40 years in patients with steroid-sensitive nephrotic syndrome (NSSS) presenting frequent relapses (NSRF) or steroid dependence (NSSD). However, the long-term success of treatment with cyclophosphamide is difficult to predict. The objectives of this study are to determine long-term outcomes of cyclophosphamide and identify the factors associated with sustained remission.

METHODS

We retrospectively studied the data from 50 patients with idiopathic nephrotic syndrome, treated by oral cyclophosphamide and followed at service of pediatric for more than 8 years for idiopathic nephrotic syndrome and related factors for survival without relapse were evaluated by univariate analysis.

RESULTS

The median age at the time of diagnosis was 4.3 years, and median follow-up time was 1.7 years with the median of 8 years at the first use of CYC. Patients had received a median cumulative dose of 168mg/kg. At the end of follow-up, 38% of patients entered into remission after using CYC while 62% failed to respond and further relapses then occur. The median time of stopping corticosteroid therapy was three month. The survival without relapse was respectively 56% (28 patients), 52% (26 patients), 48% (24 patients), and 38% (19 patients), at 6 months, one year, two years and more than two years. In univariate analysis, the survival without relapse was related to the age at the moment of starting the therapy par CYC (the median was 5 months for an age < 8 years and 41 months for an age≥8 years; P=0.049), the type of nephrotic syndrome [36 months for SNRF, 4 months for NSSD and nephrothic syndrome steroid resistant (NSSR); P=0.068], and the histological lesion (6 months for diffuse mesangial proliferation, 2 months for segmental glomerulosclerosis; P=0.009). The age at the moment of diagnosis, the sex and the cumulative dose of CYC did not have significant influence.

CONCLUSION

The results presented in this study suggest the use of oral cyclophosphamide for short period remain second line effective therapy. Further well-designed trials are required to evaluate the efficacy of other steroid-sparing agents.

Mycophenolate mofetil in steroid-dependent idiopathic nephrotic syndrome

BACKGROUND

Prospective studies have established the mycophenolate mofetil (MMF) efficiency in childhood idiopathic nephrotic syndrome (INS) but reports on the long-term outcome are lacking. Moreover, the search for factors influencing its efficiency would be useful to define its place among the other treatments.

METHODS

We performed a monocentric retrospective study including 96 children with steroid-dependent INS followed for 4.7 years (median) (IQ 3-6) after the onset of MMF treatment. The characteristics of responder patients (n = 74), as defined by a 50 % decrease of relapse rate and/or a 60 % decrease of steroid dose, and of non-responder patients (n = 22) were compared by univariate analysis and multivariate logistic regression.

RESULTS

Withdrawal of prednisone was achieved in 48/96 patients after a median duration of 18.1 months (IQ 7.8-30.0) of MMF. Only 26/48 patients did not relapse under MMF alone. After MMF was stopped in these patients, only six remained in remission without any treatment at last follow-up. Responders had a shorter time to remission at the first flare (9.5 vs. 15 days, p = 0.02), a shorter disease duration prior to the onset of MMF (22.2 vs. 94.5 months, p = 0.001), and were younger at the MMF initiation (6.7 vs. 10.1 years, p = 0.02) than non-responder patients. The age of MMF initiation was an independent factor associated with efficiency (OR = 0.80, 95 % CI [0.69, 0.93], p < 0.01).

CONCLUSIONS

MMF is more efficient in young patients treated early in the disease course. Nevertheless, MMF has no remnant effect while nearly all patients relapsed after withdrawal of the drug.

Extending prednisolone treatment does not reduce relapses in childhood nephrotic syndrome

Prolonged prednisolone treatment for the initial episode of childhood nephrotic syndrome may reduce relapse rate, but whether this results from the increased duration of treatment or a higher cumulative dose remains unclear. We conducted a randomized, double-blind, placebo-controlled trial in 69 hospitals in The Netherlands. We randomly assigned 150 children (9 months to 17 years) presenting with nephrotic syndrome to either 3 months of prednisolone followed by 3 months of placebo (n=74) or 6 months of prednisolone (n=76), and median follow-up was 47 months. Both groups received equal cumulative doses of prednisolone (approximately 3360 mg/m(2)). Among the 126 children who started trial medication, relapses occurred in 48 (77%) of 62 patients who received 3 months of prednisolone and 51 (80%) of 64 patients who received 6 months of prednisolone. Frequent relapses, according to international criteria, occurred with similar frequency between groups as well (45% versus 50%). In addition, there were no statistically significant differences between groups with respect to the eventual initiation of prednisolone maintenance and/or other immunosuppressive therapy (50% versus 59%), steroid dependence, or adverse effects. In conclusion, in this trial, extending initial prednisolone treatment from 3 to 6 months without increasing cumulative dose did not benefit clinical outcome in children with nephrotic syndrome. Previous findings indicating that prolonged treatment regimens reduce relapses most likely resulted from increased cumulative dose rather than the treatment duration.

[Mycophenolate mofetil restores renal function and spares steroids during idiopathic nephrotic syndrome in children. A cohort study]

Renal function evolution during idiopathic nephrotic syndrome depends on treatment toxicity. Cyclosporin is effective as a steroid-sparing agent but patients are dependant on this drug, which can lead to renal toxicity. Mycophenolate mofetil, a widely used drug in organ transplantation, has short-term beneficial effects in glomerular diseases, including idiopathic nephrotic syndrome. Little is known about mycophenolate mofetil in children and long-term evolution. We analysed a cohort of 12 children with steroid-dependant nephrotic syndrome due to minimal change disease in remission with cyclosporine therapy. They were switched to mycophenolate mofetil, when renal toxicity was diagnosed. We evaluated the number of relapses, tolerance of this new treatment, renal function and body mass index under mycophenolate. After a follow-up of 31.25 months, mycophenolate mofetil alone was effective in preventing relapses in eight patients, without side effects. Renal function significantly improved and the final body mass index decreased. Three patients relapsed on discontinuation of mycophenolate mofetil. The results suggest that mycophenolate mofetil is effective and safe in preventing relapses in steroid-dependant nephrotic syndrome. Furthermore, switching from cyclosporine to mycophenolate mofetil restores renal function. Therefore, mycophenolate mofetil might be considered as an alternative to cyclosporine, to preserve renal function and spare steroids during idiopathic nephrotic syndrome in children.

Bacterial superantigen TSST-1 attenuates suppressive efficacy of glucocorticoids and calcineurin inhibitors against blastogenesis of peripheral blood mononuclear cells from patients with antineutrophil cytoplasmic antibody-associated vasculitis and nephrosis

Successful immunosuppressive therapy is critical for the treatment of patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis and nephrosis. However, a considerable number of patients have shown clinical resistance to therapy. Bacterial infection might influence the clinical response of patients to immunosuppressive drugs, but few studies have been carried out to investigate the effect of bacterial superantigens on the efficacy of the drugs in these patients. We evaluated the suppressive efficacy of prednisolone, methylprednisolone, cyclosporine, and tacrolimus on the blastogenesis of PBMCs obtained from 12 ANCA-associated vasculitis patients (ANCA patients), eight patients with nephrotic syndrome, and eight healthy subjects. PBMC-stimulation index was calculated from the formula: [3H]thymidine incorporated in the presence of stimulant (dpm)/[3H]thymidine incorporated in the absence of stimulant (dpm). In vitro drug concentrations giving 50% inhibition (IC50s) of PBMC blastogenesis stimulated with concanavalin A (con A) or toxic shock syndrome toxin 1 (TSST-1) derived from Staphylococcus aureus (S. aureus) were calculated. The IC50 values for the four drugs evaluated in TSST-1-stimulated PBMCs were significantly higher than those evaluated in con A-stimulated PBMCs in both ANCA patients and nephrosis patients (p<0.012-0.044). Whereas, the IC50 values for these immunosuppressive drugs, except methylprednisolone, were not significantly different between con A- and TSST-1-stimulated PBMCs in healthy subjects. The stimulation index was not significantly different between the con A- and TSST-1-stimulated PBMCs in either of the subject groups. These observations raise the possibility that TSST-1 induced by S. aureus infection attenuates the clinical efficacy of glucocorticoids and calcineurin inhibitors in ANCA patients and nephrosis patients.