Efficacy and safety of losartan in children with Alport syndrome--results from a subgroup analysis of a prospective, randomized, placebo- or amlodipine-controlled trial.

BACKGROUND: No prospective, randomized, double-blind trials of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers have previously been reported in adults or children with proteinuria secondary to Alport syndrome. METHODS: This 12-week, double-blind multinational study investigated the effects of losartan 0.7-1.4 mg/kg/day compared with placebo (normotensive patients) or amlodipine 0.1-0.2 mg/kg/day up to 5 mg/day (hypertensive patients) on proteinuria [early morning-void urinary protein/creatinine ratio (UPr/Cr), baseline ≥ 34 mg/mmol] in 30 children of up to 17 years of age with Alport syndrome. RESULTS: Twelve weeks of treatment with losartan significantly reduced proteinuria compared with placebo/amlodipine: losartan -14.7 mg/mmol (interquartile range -49.7 to -5.7 mg/mmol) or 31.6% reduction using a mixed model approach versus placebo/amlodipine 2.3 mg/mmol (-26.0 to 18.1 mg/mmol), P = 0.01 or 2.3% increase using a mixed model approach. Adverse event incidence was low and comparable between losartan and placebo/amlodipine groups. CONCLUSIONS: Losartan significantly lowered proteinuria and was well tolerated after 12 weeks of treatment in children aged 1-17 years with proteinuria secondary to Alport syndrome with or without hypertension, a population that has not previously been rigorously studied.

Randomized, double-blind, controlled study of losartan in children with proteinuria.

BACKGROUND AND OBJECTIVES: No large, randomized, double-blind trials in children with proteinuria treated with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers have previously been reported. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This 12-week, double-blind, multinational study investigated the effects of losartan 0.7 to 1.4 mg/kg per day compared with placebo (normotensive stratum) or amlodipine 0.1 to 0.2 mg/kg per day up to 5 mg/d (hypertensive stratum) on proteinuria (morning-void urinary protein-creatinine ratio, baseline > or =0.3 g/g) in 306 children up to 17 years of age. RESULTS: Twelve weeks of treatment with losartan significantly reduced proteinuria compared with amlodipine/placebo: losartan -35.8% (95% confidence interval: -27.6% to -43.1%) versus amlodipine/placebo 1.4% (95% confidence interval: -10.3% to 14.5%), P < or = 0.001. Significance remained after adjustment for differences across treatment groups in change in BP (losartan produced incremental systolic and diastolic BP reductions versus amlodipine of 5.4 and 4.6 mmHg, respectively; and versus placebo of 3.8 and 4.0 mmHg, respectively). Proteinuria reduction was consistently observed in the normotensive (-34.4% losartan; 2.6% placebo) and hypertensive (-41.5% losartan; 2.4% amlodipine) strata, and in all prespecified subgroups, including age, gender, race, Tanner stage, weight, prior therapy with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, as well as among the most common etiologies of proteinuria. Adverse event incidence was low and comparable in all groups. CONCLUSIONS: Losartan significantly lowered proteinuria and was well tolerated after 12 weeks in children aged 1 to 17 years with proteinuria with or without hypertension, a population that has not previously been rigorously studied.

Induction of chronic renal allograft injury by injection of a monoclonal antibody against a donor MHC Ib molecule in a nude rat model.

BACKGROUND: Chronic allograft injury induced by immunological as well as non-immunological mechanisms is still a major cause of long-term graft loss after renal transplantation. Major histocompatibility complex (MHC) incompatibilities as well as donor-specific alloantibodies are known risk factors, but the interaction of cellular and humoral mechanisms leading to allograft damage remains to be defined. The aim of this study was to analyze the impact of donor-specific post-transplant antibodies against a non-classical MHC Ib antigen apart from T-cell-dependent immune response. Therefore, we utilized a transplant rat model injecting a moAb directed against a donor MHC Ib molecule into athymic nude recipients lacking an immunocompetent T-cell system. METHODS: F344 kidneys were transplanted into LEW.RNU rats. Donor and recipient differ in the RT1.C locus (MHC Ib) but are phenotypically identical for the RT1.A (MHC I) and RT1.B/D (MHC II) loci. A moAb directed against the donors RT1.C(lv1) was injected into recipients with stable graft function. A control group remained untreated after transplantation. The rats were monitored for renal function and grafts were analyzed for morphological changes, infiltrating cells and C4d deposition. RESULTS: Antibody-infused rats developed renal impairment with massive urine albumin excretion. Histological changes consistent with antibody-mediated injury were interstitial fibrosis, tubular atrophy and severe glomerulopathy accompanied by an infiltrate of numerous macrophages. At time of death, grafts were negative for C4d at the peritubular capillaries and arterial endothelium. CONCLUSION: Antibodies directed against a MHC Ib antigen are able to induce allograft injury in T-cell-deficient rats. This model underlines the role of non-classical MHC disparities for long-term allograft survival and demonstrates the long-term results of antibody-induced allograft damage.

Renal arterial resistance index and computerized quantification of fibrosis as a combined predictive tool in chronic allograft nephropathy.

The renal arterial resistance index (RI) and the PicroSirius-Red stained cortical fractional interstitial fibrosis volume (VintFib) proved to be two independent methods that are reliable predictive factors of poor renal allograft outcome. No data have been published, which define the correlation between ultrasound assessment and quantitative morphologic changes. Renal biopsies were performed in 56 children according to increases in s-creatinine >10%. VintFib was calculated by computerized image analysis. RI was determined in two segmental arteries, 1 yr after transplantation and at the time-point of biopsy. RIs 1 yr after transplantation correlated significantly with RIs at time of biopsy (r = 0.58, p < 0.001). VintFib was higher in children with a RI = 80 than in children with a RI < 80 (mean VintFib = 9.5 +/- 3.2% vs. 5.2 +/- 5.1%, p = 0.004). In children with VintFib > 10%, the mean RI was 77 +/- 5 compared with 69 +/- 6 in patients with VintFib < 10% (p = 0.0002). The highest positive predictive value to detect the risk of decline of GFR at 2 yr after biopsy was 98% when an RI = 80% was associated with a VintFib > 10%. For VintFib > 10% or RI = 80 alone, it was 87% or 67%, respectively. The combined measurement of RI and VintFib is a reliable predictive tool for the risk of developing long-term graft dysfunction after kidney transplantation.

Mycophenolate mofetil-induced reversal of glomerular filtration loss in children with chronic allograft nephropathy.

BACKGROUND: Mycophenolate mofetil (MMF) has been used for the treatment of chronic allograft nephropathy (CAN) in adults with inconsistent results, but data in children are rare. To evaluate its impact on advanced CAN, we studied changes in glomerular filtration rate (GFR) and the correlation of GFR changes to histology. METHODS: Thirty-six children (13.1+/-3.6 years) with a progressive decline in GFR of 16.9+/-12.4 mL/min per 1.73 m2/year and biopsy confirmed CAN 4.3+/-2.9 years after transplantation were studied. MMF was added to conventional immunosuppression (IS) consisting of cyclosporine (CsA) and prednisolone (n=26) or tacrolimus (n=1) or replaced azathioprine in triple IS (n=9). Alterations of GFR were correlated to histologic guidelines according to the Banff chronic score (BCS). RESULTS: One year after conversion, 22 (61%) children showed a rise in GFR (7.5+/-6 mL/min per 1.73 m2), 8 (22%) remained stable, and 6 (17%) showed a further decline of GFR (7.4+/-2 mL/min per 1.73 m2). Mean CsA trough levels were 114 ng/mL before and 98 ng/mL 1 year after conversion. MMF side effects required dose reduction in 14 children. Children responding to MMF with increasing GFR showed a trend toward less fibrosis, less incidence of vasculopathy, and transplant glomerulopathy in the initial biopsy but had a similar incidence of borderline tubulitis compared with the other groups. CONCLUSIONS: Cotreatment with MMF reversed the progressive loss of GFR in approximately two thirds of children with CAN for at least 1 year. Less chronicity signs in histology seem to indicate a more favorable response to treatment.

Computer-assisted quantification of fibrosis in chronic allograft nephropaty by picosirius red-staining: a new tool for predicting long-term graft function.

BACKGROUND: Chronic allograft nephropathy (CAN) has become the predominant limiting factor for long-term transplant survival. A cardinal histomorphologic correlate for CAN is interstitial fibrosis. Currently, no method has been established in routine use that reliably quantifies the extent of interstitial fibrosis in renal grafts. We have used staining with picrosirius red followed by computerized image analysis to study the correlation between graft fibrosis and future development of glomerular filtration rate (GFR) in a group of children with advanced CAN. METHODS: Renal biopsies were performed in 56 children (mean age, 13.7+/-3.6 years) after a mean period of 4.6+/-3.1 years after transplantation because of significant increases in serum creatinine. All biopsy specimens were stained with picrosirius red. The magnitude of fibrotic tissue was calculated by computerized image analysis. Linear regression analysis was performed correlating the intensity of graft fibrosis and the changes in the GFR at the time points of renal biopsy and 2 years later. RESULTS: There was a significant positive correlation (r=0.62, P<0.001) between the picrosirius red-stained cortical fractional interstitial fibrosis volume (V(intFib)) and the decrease of GFR within 2 years postrenal biopsy. When V(intFib) was below 5%, 82% of the patients had an increase in GFR within 2 years. Ninety-three percent of the patients with greater than 10% of fibrosis experienced a worsening renal function after 2 years. When comparing patients with stable GFR with patients having a decrease in GFR, a highly significant difference in V(intFib) was found (P=0.008). CONCLUSIONS: The quantitative measurement of fibrosis by picrosirius red staining appears to be a useful prognostic indicator for estimating long-term graft function in CAN and may provide an easy, fast, and inexpensive tool helpful for treatment decisions in patients developing CAN.

Drug-induced lupus as a cause of relapsing inflammatory disease after renal transplantation.

We discuss the case of an 18-year-old-boy presenting with relapsing fever, arthralgia, myalgia and renal failure, 7 yr after renal transplantation. A thorough diagnostic work-up for infectious and inflammatory diseases revealed a mastoiditis and atypical mycobacteria, but symptoms persisted after treatment. Persistent antinuclear antibodies in combination with cardiolipin and myeloperoxidase antibodies, despite negative dsDNA antibodies, suggested a drug induced lupus-like syndrome. Six months after withdrawal of dihydralazine, all symptoms had disappeared. Drug-induced lupus should be considered as an important differential diagnosis in transplanted patients with recurrent inflammatory disease in conjunction with lupus-like symptoms and negative dsDNA antibodies. It may prevent a potentially hazardous reduction of immunosuppression in persistent inflammation.

Quantitative gene expression of TGF-beta1, IL-10, TNF-alpha and Fas Ligand in renal cortex and medulla.

BACKGROUND: Inflammatory, fibrogenic or apoptotic processes in the kidney are regulated by intra- and intercellular mediators. Intrarenal upregulation of genes may precede structural changes by days and can be examined in extremely small amounts of tissue. With the advent of new quantitative PCR methods results of gene expression are available within few hours after kidney biopsies. METHODS: In order to establish reference values for intrarenal gene expression of TGF-beta1, IL-10, TNF-alpha and Fas Ligand in renal cortex and medulla, we analysed 28 histologically normal kidney samples available after tumour nephrectomy by quantitative real-time PCR. After reverse transcription of isolated RNA, cDNA aliquots were quantified for target genes using the threshold cycle (C(t)) method normalized for the house keeping gene GAPDH. RESULTS: Expression of target genes was lower in cortex as compared to medulla, but the differences were only significant for IL-10 (P=0.0125). TGF-beta1 was found with the highest gene expression about five PCR-cycles (delta C(t)) after GAPDH with markedly lower results for TNF-alpha (delta C(t) approximately 9), IL-10 (approximately 12) and Fas Ligand (approximately 14). CONCLUSIONS: These results are the first reported reference values for human intrarenal gene expression which should facilitate interpretation of data from native or transplant kidneys in future studies.

Single centre experience with basiliximab in paediatric renal transplantation.

BACKGROUND: Introduction of IL-2-receptor antagonists has led to significantly decreasing numbers of acute rejection episodes in renal transplantation in adults. No data are available in paediatric recipients. METHODS: Between 1997 and 2000, 78 renal transplantations were performed in 77 children aged 0.5-16 years. Basiliximab, cyclosporin A (CsA) and prednisolone were administered in 48 children (age 7.8 +/- 5.3 years) and compared with 29 children (age 7.3 +/- 5.2 years) receiving CsA and prednisolone only. The number of acute rejections, survival, glomerular filtration rate (GFR) and side effects were determined for 3 years after transplantation. RESULTS: All 77 patients survived the observation period. One year graft survival in the basiliximab group was 95%, which is similar to the comparison group (93%). Children receiving basiliximab showed a lower incidence of acute rejection than the comparison group (14% vs 34%). The calculated GFR was lower in the basiliximab group when discharging from hospital, with 51 compared with 66 ml/min/1.73 m(2) in the non-basiliximab group. This was associated with higher CsA trough levels (214 vs 174 ng/ml) in the basiliximab patients. After 1 year the GFR was comparable in both groups (58 vs 52 ml/min/1.73 m(2)). CONCLUSIONS: Basiliximab offers excellent allograft survival, a lower incidence of acute rejections and almost no side effects. Therefore it can be recommended for routine immunosuppressive therapy in paediatric renal transplantation.

Activated intrarenal transcription of CTL-effectors and TGF-beta1 in children with focal segmental glomerulosclerosis.

BACKGROUND: The pathogenesis of childhood nephrotic syndrome (NS), whether the lesion is minimal change disease (MCD) or focal segmental glomerulosclerosis (FSGS), remains elusive. Based on the presence of elevated cytokine levels in peripheral blood, a T cell-induced injury could be postulated. METHODS: To test the hypothesis that infiltrating T cells actively contribute to the glomerular injury in children with NS, we studied the intrarenal transcription of various T cell-related chemokines, cytokines and cytotoxic T-lymphocyte (CTL) effector molecules in the renal biopsy tissue of 52 nephrotic children with a variety of histologic lesions. Intrarenal gene expression was studied using reverse transcription (RT)-assisted-polymerase chain reaction (PCR). RESULTS: Interleukin-2 (IL-2) and IL-4 transcripts were not observed in any of the specimens. IL-2 receptor alpha mRNA was detected in 24 of 40 proteinuric patients, but also in 6 of 10 patients in remission and showed no significant differences with regard to steroid response. Intrarenal gene expression of CTL mediators and transforming growth factor-beta1 (TGF-beta1) was noted particularly in patients with progressive disease leading to chronic renal failure. TGF-beta1 gene expression was noted in 23 of 29 steroid resistant (SR) children with NS not caused by lupus nephritis and in 18 of 20 FSGS patients. In contrast TGF-beta1 gene expression was detected in only 3 of 14 steroid-sensitive patients (P < 0.001). Two of these patients later developed FSGS. In patients with steroid-resistant NS, intrarenal TGF-beta1 gene expression showed a positive predictive value of 90% and a negative predictive value of 88% to identify FSGS (P < 0.0001). CONCLUSION: These results support the notion that immunologically mediated events contribute to the progressive renal damage seen in children with FSGS.