Management of the difficult nephrotic patient

Increased steroid responsiveness of young children with nephrotic syndrome in Nigeria

A previous study on the nephrotic syndrome (NS) in our unit showed that the histological patterns associated with steroid resistance were more common in children over 5 years of age.

AIM

The aim of the study was to determine the incidence of steroid-responsiveness amongst nephrotic children <or=5 years.

SUBJECTS AND METHODS

All children with NS aged <or=5 years at the onset of disease presenting to University College Hospital, Ibadan were enrolled. Prednisolone was given daily, 60 mg/m2, for 4 weeks and then 40 mg/m2 on alternate days for at least 12 weeks.

RESULTS

Twenty children (9 boys and 11 girls) were enrolled between 1999 and 2002. The median age (range) at onset of disease was 4 (2-5) years. Remission was achieved in 12 (60%) children.

CONCLUSION

There is a satisfactory response to prednisolone in two-thirds of Nigerian children aged <or=5 years with NS.

Permeability factors in nephrotic syndrome and focal segmental glomerulosclerosis

Circulating permeability factors have been identified in the plasma of patients with focal segmental glomerulosclerosis (FSGS). Post-transplant recurrence of proteinuria, improvement of proteinuria after treatment with plasmapheresis, and induction of proteinuria in experimental animals by plasma fractions each provide evidence for such plasma factors. Advanced proteomic methods have identified candidate molecules in recurrent FSGS. We have proposed cardiotrophin-like cytokine-1 as an active factor in FSGS. Another potential permeability factor in FSGS is soluble urokinase receptor. In our studies, in vitro plasma permeability activity is blocked by substances that may decrease active molecules or block their effects. We have shown that the simple sugar galactose blocks the effect of FSGS serum in vitro and decreases permeability activity when administered to patients. Since the identities of permeability factors and their mechanisms of action are not well defined, treatment of FSGS is empiric. Corticosteroids are the most common agents for initial treatment. Calcineurin inhibitors, such as cyclosporine A, and tacrolimus and immunosuppressive medications, including mycophenylate, induce remission is some patients with steroid-resistant or -dependent nephrotic syndrome. Therapies that diminish proteinuria and slow progression in FSGS as well as other conditions include renin-angiotensin blockade, blood pressure lowering and plasma lipid control. Use of findings from in vitro studies, coupled with definitive identification of pathogenic molecules, may lead to new treatments to arrest FSGS progression and prevent recurrence after transplantation.

Dose- and time-dependent glucocorticoid receptor signaling in podocytes

Glucocorticoids (GC) are the primary therapy for idiopathic nephrotic syndrome (NS). Recent evidence has identified glomerular podocytes as a potential site of GC action in this disease. The objectives of this study were to determine the presence of key components of the glucocorticoid receptor (GR) complex and the functionality of this signaling pathway in podocytes and to explore potential opportunities for manipulation of GC responsiveness. Here, we show that cultured murine podocytes express key components of the GR complex, including the GR, heat shock protein 90, and the immunophilins FKBP51 and FKBP52. The functionality of GR-mediated signaling was verified by measuring several GC (dexamethasone)-induced responses, including 1) increases in mRNA and protein levels of selected GC-regulated genes (FKBP51, phenol sulfotransferase 1, αB-crystallin); 2) downregulation of the GR protein; 3) increased phosphorylation of the GR; and 4) translocation of the GR into the nuclear fraction. Dexamethasone-induced phosphorylation and downregulation of GR protein were also demonstrated in isolated rat glomeruli. Podocyte gene expression in response to dexamethasone was regulated at both the transcriptional and posttranscriptional levels, the latter also including protein degradation. Short-term, high-dose GC treatment resulted in similar changes in gene expression and GR phosphorylation to that of long-term, low-dose GC treatment, thus providing a molecular rationale for the known efficacy of pulse GC therapy in NS. Induction of FKBP51 and downregulation of the GR represent negative feedback mechanisms that can potentially be exploited to improve clinical GC efficacy. Collectively, these findings demonstrate the presence of key molecular components of the GR signaling pathway and its functionality in podocytes and identify novel opportunities for improving clinical GC efficacy in the treatment of NS.

Pulse steroid therapy

Intravenous supra-pharmacological doses of corticosteroids are used in various inflammatory and autoimmune conditions because they are cumulatively less toxic than sustained steroid treatment at lower quantitative dosage. Their action is supposed to be mediated through non-genomic actions within the cell. Common indications for use in children include steroid resistant and steroid dependent nephrotic syndrome, rapidly progressive glomerulonephritis, systemic vasculitis, systemic lupus erythematosus, acute renal allograft rejection, juvenile rheumatoid arthritis, juvenile dermatomyositis, pemphigus, optic neuritis, multiple sclerosis and acute disseminated encephalomyelitis. Methylprednisolone and dexamethasone show similar efficacy in most conditions. Therapy is associated with significant side effects including worsening of hypertension, infections, dyselectrolytemia and behavioral effects. Adequate monitoring is essential during usage.

Corticosteroid-resistant nephrotic syndrome with focal and segmental glomerulosclerosis : an update of treatment options for children

Corticosteroid-resistant nephrotic syndrome (CRNS) with focal and segmental glomerulosclerosis (FSGS) is a heterogeneous disorder and the most severe and frequent type of all glomerulopathies in children leading to end-stage renal failure. The podocyte is at the center of development and progress of FSGS; this unique cell type plays a major role in the integrity of glomerular structure and permeability. The rate of complete remission of CRNS after induction therapy using different immunosuppressant agents is reported to range between 30% and 84%, depending on the treatment schedule and on the underlying defects of FSGS. Children with genetic types of FSGS barely respond to immunosuppressant therapies and over-treatment prior to transplantation should be avoided. The response of children with an idiopathic type of FSGS to immunosuppressants is superior to those with genetic FSGS. However, many children with idiopathic FSGS do not enter complete remission if they are under-treated, for example, with short-term immunosuppressant monotherapies. If immunosuppressant treatment fails, these patients will have to undergo renal transplantation. However, as unknown pathogenetic mechanisms may persist, more than one-third of these patients with idiopathic FSGS develop a rapid recurrence of CRNS that responds poorly to further long-term therapeutic attempts. In contrast with previously published data, this review takes into account recently identified genetic etiologies of CRNS, and superior results with long-term combination therapy in idiopathic forms to avoid over- and under-treatment.

The treatment of relapsing primary nephrotic syndrome in children

OBJECTIVE

To explore better therapy and reduce the rate of re-relapse of primary nephritic syndrome in children who had been treated with corticosteroids but relapsed.

METHODS

Eighty relapsers were enrolled from Jan. 1994 to Apr. 2000, who were randomly divided into two groups. The treatment group (n=39) had been treated with tripterysium glucosides for three months, with the control group (n=41) members were treated with cyclophosphmide (CTX) by intermission intravenous pulse, with total dose of CTX not being more than 150 mg/kg. Prednisone, meanwhile, was given to both groups. The total treatment period of prednisone was prolonged by 12-18 months.

RESULTS

After following up for 3-7 years, the re-relapse rates of both groups were observed. The re-relapse rate of the treatment group was 28.2% to 29.3% in the CTX-controlled group. The re-relapse rates between two groups were almost similar, and with no observed significant difference (P>0.05). The side effect of tripterysium glucosides was less than that of CTX.

CONCLUSION

For the treatment of relapsing nephritic syndrome in children, the combination of tripterysium glucosides and prolonged corticosteroid therapy is as effective as the regimen of CTX plus prolonged use of prednisone.

Oral mizoribine pulse therapy for patients with steroid-resistant and frequently relapsing steroid-dependent nephrotic syndrome

BACKGROUND

We investigated the efficacy of oral mizoribine pulse therapy (mizoribine-pulse) for cyclosporin (CyA)-dependent, steroid-resistant nephrotic syndrome (SRNS) and frequently relapsing, steroid-dependent nephrotic syndrome (FR-SDNS).

METHODS

One child with CyA-dependent SRNS and eight children with CyA-dependent FR-SDNS were treated with mizoribine-pulse (daily dose: 10 mg/kg; maximum total dose 500 mg). We compared clinical manifestations before and after mizoribine-pulse, and studied the changes in serum mizoribine concentration in each patient on days when mizoribine was administered.

RESULTS

Four patients had no subsequent relapses (responders). Two of the four responders discontinued prednisolone and CyA, the other two discontinued CyA. Although each of the five other patients (non-responders) experienced single subsequent relapses, the dosages of prednisolone and CyA after mizoribine-pulse were decreased significantly compared with before mizoribine-pulse. The peak blood concentration of mizoribine in the responders was higher than in the non-responders (3.6+/-0.9 vs 1.8+/-0.4 microg/ml).

CONCLUSIONS

Mizoribine-pulse may be effective for some patients with CyA-dependent SRNS and FR-SDNS.

Use of mycophenolate mofetil in steroid-dependent and -resistant nephrotic syndrome

Cyclosporin (Cs-A) is an effective treatment for difficult cases of nephrotic syndrome (NS), but its use can be complicated by renal toxicity and a high incidence of relapses after withdrawal. We reviewed the charts of 10 Cs-A-dependent patients and 4 patients with steroid-dependent nephrotic syndrome (SDNS) not previously treated with Cs-A therapy. All patients had persistent NS, even after prior treatment with oral cyclophosphamide. Of 10 patients treated with Cs-A, 4 had surveillance renal biopsies consistent with Cs-A toxicity, and 8 of 10 had interstitial fibrosis prior to mycophenolate mofetil (MMF). Patients were treated with MMF, at 1,200 mg/m(2) per day, in an attempt to allow weaning of Cs-A and/or steroid therapy, and reduce the frequency of relapses. Overall, a significant decrease in frequency of relapses was noted after initiation of MMF therapy. In addition, 5 patients were weaned off Cs-A by 1-2 years of follow-up. One patient was weaned off Cs-A and MMF, and remained in complete remission. However, the subgroup of patients with frequently relapsing SDNS not treated with Cs-A appeared to have a reduction in the number of relapses while on MMF that did not reach statistical significance. Two patients with intractable steroid-resistant NS continued to relapse repeatedly on MMF and Cs-A therapy. We conclude that in this small, single-center, uncontrolled experience, MMF therapy in patients with Cs-A-dependent NS appears to be effective in reducing Cs-A exposure. In addition, MMF appears to significantly decrease the frequency of relapses in this patient population. Further controlled studies are warranted to better define the potential efficacy and side effects of long-term MMF therapy in this setting.

Characterization of proteinuria in asymptomatic family members and household contacts of children with hepatitis B virus-associated membranous nephropathy

The biosocial background in which the hepatitis B virus (HBV) carrier state with membranous nephropathy (MN) develops was studied by evaluating HBV carriage and proteinuria among 195 family members and household contacts of 31 index HBV carrier children with MN. Unrelated individuals from the communities of these index cases who were negative for HBV served as controls (n = 123). HBV was determined by using third-generation enzyme-linked immunosorbent assay, slot-blot hybridization, and nested polymerase chain reaction. Patterns of proteinuria were determined by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis; immunoglobulin G and haptoglobulin were suggestive of MN. Seventy-two members (36.9%) of the study group (n = 195) were HBV carriers; 21 of these carriers (29.2%) had proteinuria. Twenty-eight members (41.2%) of the study group who were HBV negative (n = 68) and 26.8% of the controls showed proteinuria. This lack of association between HBV carriage and proteinuria remained when controlled for sex and family relationship. HBV was not protective against the development of proteinuria. Proteinuria suggestive of MN was strongly associated with an abnormal protein-creatinine ratio (P: = 0.001), but was not significantly different between subjects and controls (8.7% versus 6.5%; P: = 0.5). Genetic influences or environmental exposures in these subjects may be responsible for the proteinuria, suggesting underlying glomerular basement membrane damage. Discordance between the HBV carrier state and patterns of proteinuria in the study group suggest that HBV and MN may not be causally related or may reflect exceptional interaction between specifically vulnerable individuals and HBV.

Treatment of children with steroid refractory idiopathic nephrotic syndrome: the Kuwaiti experience

Data on the treatment and outcome of Kuwaiti children with steroid refractory idiopathic glomerulonephritis (SRIGN), i.e. nephrotic syndrome who failed an eight-week course of prednisone, were collected retrospectively from the records of children attending the two renal centers of Kuwait between January 1, 1990 to December 31, 1996. During those seven years, a total of 34 Kuwaiti children were diagnosed to have SRIGN. Histologically, 22 (65%) of those patients had minimal change, 5 (15%) focal segmental GN, 2 (6%) non-IgA mesangioproliferative GN and one membranous GN. Twenty-two patients had manifested frequent relapses, six were steroid-dependent and six were steroid-resistant. Treatment options were in the following order: (a) small maintenance-dose of corticosteroids (< 0.5 mg/kg/alternate days); (b) cyclophosphamide and or chlorambucil for a single eight week-course or eight then 12 week courses (c) cyclosporin A for three months. The response to therapy was as follows: nine children were cured with low-dose corticosteroids; 17 with chlorambucil and/or cyclophosphamide; and five with cyclosporin A. At the end of study, only three children failed such drug therapy, two of who had focal segmental glomerulosclerosis.

HBV and proteinuria in relatives and contacts of children with hepatitis B virus-associated membranous nephropathy

BACKGROUND

Hepatitis B virus (HBV)-associated membranous nephropathy (HBVMN) is an important cause of childhood nephrotic syndrome in regions endemic for the virus, but little is understood of the biosocial context in which the disease develops. We evaluated HBV status and proteinuria in family members and household contacts of index children with HBVMN to test the hypothesis that HBV carriage and asymptomatic proteinuria are closely linked and may be causally associated.

METHODS

Thirty-one black children with biopsy-proven HBVMN were the index cases. One hundred and fifty-two family members and 43 black household contacts were the subjects of the study. We assessed HBV carrier status by testing for HBV antigens and antibodies using enzyme-linked immunosorbent assays (ELISA) and for HBV DNA by using slot-blot hybridization and the polymerase chain reaction. Sequencing of the precore region of HBV was done in a subset of both index cases and subjects. Proteinuria was assessed by measuring the urinary protein/creatinine ratio.

RESULTS

Seventy-two (37%) of the 195 family members and household contacts were HBV carriers, and 53 (27%) had a protein/creatinine ratio greater than the physiological limit. The frequency of abnormal proteinuria was not significantly different in those with [22 out of 72 (30.5%)] or without [33 out of 104 (32%)] HBV carriage. This lack of association remained when carriers were classified into those who were HBsAg positive only and those with active viral replication (HBsAg and/or HBeAg and/or HBV DNA; P = 0.01). Family members were more predisposed to HBV carriage than household contacts, but abnormal proteinuria was present with equal frequency (P = 0.48). Age had a significant impact on proteinuria, with children less than five years being more likely to have abnormal proteinuria (P = 0.008). The prevalence of abnormal proteinuria in family members and household contacts of the index cases was more than that in community-based controls. The 10 index HBVMN cases and the 14 family members and household contacts who were tested all had HBV of genotype A.

CONCLUSION

These results suggest that the family members and household contacts of children with HBVMN are at very high risk of HBV carriage; they also have asymptomatic proteinuria at a significantly higher rate than community-based controls. The HBV carrier status was not associated with proteinuria, a finding supported by peak prevalences of proteinuria in those under five years but no corresponding peak for HBV carriage. Proteinuria may indicate glomerular basement membrane dysfunction. Environmental and social factors may underpin development of these two covert disorders, but are insufficient to account for the index cases of HBVMN. The emergence of children with HBVMN from such households additionally depends on unidentified and possibly genetic factors.