Factors related to recurrence of proteinuria in childhood IgA nephropathy.

BACKGROUND: Proteinuria remission is the most significant predictive factor for kidney outcome in childhood IgA nephropathy (c-IgAN). Even if proteinuria remission can be obtained, some patients have recurrence of proteinuria in the long-term. METHODS: This is a retrospective analysis of 312 cases of proteinuria remission among 538 consecutive children with biopsy-proven IgAN from 1976 to 2013. To elucidate the incidence and factors related to recurrence of proteinuria in c-IgAN, we compare clinical and pathological findings between patients with and without recurrence of proteinuria. RESULTS: Among 312 patients with remission of proteinuria, 91 (29.2%) had recurrence of proteinuria within the observation period (median 8 years). Using a multivariate Cox regression analysis, significant factors associated with recurrence of proteinuria were onset age (HR 1.13 [95%CI: 1.05-1.22], P = 0.002) and presence of hematuria after proteinuria remission (HR 2.11 [95%CI: 1.30-3.45], P = 0.003). The Kaplan-Meier analysis showed significant differences in CKD G3a-G5-free survival between the patients with no-recurrence of proteinuria, recurrence of proteinuria and non-proteinuria remission (P < 0.0001, log-rank test). Kidney survival was 100% in no-recurrence of proteinuria, 92.2% in recurrence of proteinuria, and 65.6% in non-proteinuria remission at 15 years. Cox analyses adjusted by proteinuria remission showed that recurrence of proteinuria (HR 03.10e9 [95%CI: NA], P = 0.003) was a significant factor associated with progression to CKD G3a-G5 in all patients with c-IgAN. CONCLUSIONS: Approximately 30% of patients with proteinuria remission had recurrence of proteinuria regardless of treatment. Both remission and recurrence of proteinuria are significant prognostic factors for kidney outcome. A higher resolution version of the Graphical abstract is available as Supplementary information.

Clinical characteristics and outcomes of immune-complex membranoproliferative glomerulonephritis and C3 glomerulopathy in Japanese children.

BACKGROUND: Membranoproliferative glomerulonephritis (MPGN) can be divided into immune-complex MPGN (IC-MPGN) and C3 glomerulopathy (C3G), which includes dense deposit disease (DDD) and C3 glomerulonephritis (C3GN). These conditions result from abnormalities in different complement pathways and may lead to different prognoses. However, there are limited studies describing the respective clinical courses. METHODS: In this study, Japanese pediatric patients diagnosed with MPGN based on kidney biopsies conducted between February 2002 and December 2022 were reclassified as having IC-MPGN or C3G (DDD or C3GN). We retrospectively analyzed the clinical characteristics and outcomes of these patients. RESULTS: Out of 25 patients with MPGN, three (12.0%) were diagnosed with DDD, 20 (80.0%) with C3GN, and two (8.0%) with IC-MPGN. There were 13 (65.0%) patients and one (33.3%) patient in remission after treatment for C3GN and DDD, respectively, and no patients with IC-MPGN achieved remission. The median follow-up period was 5.3 (2.5-8.9) years, and none of the patients in either group progressed to an estimated glomerular filtration rate < 15 ml/min/1.73 m2. Patients with C3GN presenting mild to moderate proteinuria (n = 8) received a renin-angiotensin system inhibitor (RAS-I) alone, and these patients exhibited a significant decrease in the urinary protein creatinine ratio and a notable increase in serum C3 levels at the last follow-up. CONCLUSIONS: Most patients with MPGN were diagnosed with C3GN. The remission rate for C3GN was high, and no patients developed kidney failure during the approximately 5-year follow-up. Additionally, patients with C3GN with mild to moderate proteinuria had good outcomes with RAS-I alone, but continued vigilance is necessary to determine long-term prognosis.

Clinical and pathological investigation of oligomeganephronia.

BACKGROUND: Oligomeganephronia (OMN) is a rare congenital anomaly involving the kidney and urinary tract, characterized by decreased number and compensatory hypertrophy of the nephron. It is caused by abnormal kidney development during the embryonic period, especially in patients with low birth weight; however, the actual etiology and clinical features remain unknown. We aim to reveal the clinical and pathological characteristics, treatment, and outcome. METHODS: Ten patients diagnosed with OMN between 2013 and 2020 were retrospectively investigated. The data were presented as the median ± interquartile range, and statistical significance was set at p < 0.05. RESULTS: The age at diagnosis was 14.1 years, the male-to-female ratio was 6:4, and only four cases were born with low birth weight. The estimated glomerular filtration rate (eGFR) was 62.2 mL/min/1.73 m2. The glomerulus diameter of OMN patients was significantly larger (217 vs. 154 µm, p < 0.001) in OMN patients, and the number of glomeruli of OMN patients was lower (0.89 vs. 2.05/mm2, p < 0.001) than the control group. Eight of the ten cases were identified by urinary screening. Nine patients were treated with renin-angiotensin system (RAS) inhibitors, following which proteinuria successfully decreased or disappeared. Their median eGFR was also stable, 53.3 mL/min/1.73 m2. CONCLUSIONS: As few symptoms can lead to OMN discovery, most patients were found during urine screening at school. Kidney dysfunction was observed in all patients at the time of kidney biopsy. Proteinuria has been significantly reduced and the decline rate of eGFR might be improved by RAS inhibitors. "A higher resolution version of the Graphical abstract is available as Supplementary information".

Long-term outcome of combination therapy with corticosteroids, mizoribine and RAS inhibitors as initial therapy for severe childhood IgA vasculitis with nephritis.

BACKGROUND: Patients with severe IgA vasculitis with nephritis (IgAVN) typically receive aggressive therapy as an initial approach. We have consistently performed combination therapy including corticosteroids and immunosuppressants as initial therapy for severe IgAVN over a 20-year-plus period, with only minor changes to the treatment protocol. This study seeks to reveal the efficacy of combination therapy for severe IgAVN. METHODS: We retrospectively studied 50 Japanese children diagnosed between 1996 and 2019 with clinicopathologically severe IgAVN who were defined as ISKDC classification grade IIIb-V and/or serum albumin < 2.5 g/dL. RESULTS: The median age at the onset of IgAVN was 8.0 years (IQR: 6.0-10.0). At biopsy, 44% of patients had nephrotic syndrome and 14% had kidney dysfunction. All patients were treated with combination therapy after biopsy. Abnormal proteinuria resolved after initial therapy in all 50 patients. However, eight patients (16%) had recurrence of proteinuria. Abnormal proteinuria was again resolved in three of these patients with additional treatment. At the last follow-up (median 59.5 months; IQR, 26.2-84.2), the median urine protein-to-creatine ratio was 0.08 g/gCr (IQR, 0.05-0.15), and only one patient had kidney dysfunction. CONCLUSIONS: Combination therapy provided good kidney outcomes for Japanese children with severe IgAVN. Even including recurrent cases, the degree of proteinuria was slight, and kidney function was good at the last follow-up. A higher resolution version of the Graphical abstract is available as Supplementary information.

Use of renin-angiotensin system inhibitors as initial therapy in children with Henoch-Schönlein purpura nephritis of moderate severity.

BACKGROUND: Cases of Henoch-Schönlein purpura nephritis (HSPN) with moderate severity were demonstrated to achieve good prognosis after treatment with renin-angiotensin system (RAS) inhibitors. However, some patients required additional treatment for recurrence after remission. This study aimed to clarify the effect of RAS inhibitors in HSPN cases with moderate severity, including the proportion of cases with recurrence and their response to additional treatment. METHODS: Among 126 patients diagnosed with HSPN between 1996 and 2019, 71 patients with clinicopathologically diagnosed HSPN of moderate severity, defined as ISKDC grade II-IIIa and serum albumin ≥ 2.5 g/dL, were investigated. RESULTS: Proteinuria became negative after RAS inhibitor treatment alone in all 71 cases. However, 16 (22.5%) had recurrence. Eleven recurrent cases achieved negative proteinuria again following additional treatment. At the last follow-up (median 46.5 months; IQR, 23.2-98.2), 5 patients had persistent mild proteinuria; no patients had estimated glomerular filtration rate < 90 mL/min/1.73 m2. The pathological findings in all recurrent cases were ISKDC grade IIIa. The 16 recurrent cases had significantly higher proportions of glomeruli with global/segmental sclerosis (25.0 vs. 0%, P < 0.001) and tubular atrophy/interstitial fibrosis (37.5 vs. 12.7%, P =0.0 24) than 55 cases without recurrence. CONCLUSIONS: Japanese childhood HSPN cases with moderate severity had good outcomes without need for corticosteroids or immunosuppressants, when prescribed RAS inhibitor treatment. Even in recurrent cases, abnormal proteinuria was transient, and prognosis was excellent. A higher resolution version of the Graphical abstract is available as Supplementary information.

Efficacy of combination therapy for childhood complicated focal IgA nephropathy.

BACKGROUND: Patients with immunoglobulin A nephropathy who present with focal mesangial proliferation (focal IgAN) can have a relatively good prognosis, and renin-angiotensin system inhibitor (RAS-i) is commonly used as the initial treatment. However, there are some complicated focal IgAN cases with resistance to RAS-i treatment or nephrotic-range proteinuria. Thus, combination therapy including corticosteroids is often used. This study aimed to evaluate the efficacy of combination therapy for complicated focal IgAN cases by comparing to diffuse mesangial proliferation (diffuse IgAN). METHODS: We conducted a multicenter retrospective study on 88 children who received 2-year combination therapy. The participants were classified based on pathological severity: focal IgAN (n = 26) and diffuse IgAN (n = 62). RESULTS: In total, 26 patients with focal IgAN and 52 with diffuse IgAN achieved proteinuria disappearance within 2 years (100 vs. 83.9%, P = 0.03). Moreover, the time to proteinuria disappearance was significantly shorter in the focal IgAN group than in the diffuse IgAN group (2.9 vs. 4.2 months, P < 0.01) and all patients with focal IgAN achieved proteinuria disappearance within 8 months. At the last observation (8.6 vs. 10.4 years, P = 0.13), only patients with diffuse IgAN (n = 12) had greater than stage 2 chronic kidney disease. In terms of irreversible adverse events, one patient exhibited cataracts. CONCLUSION: Combination therapy was significantly effective in patients with complicated focal IgAN. Moreover, the long-term prognosis was good, and the duration of combination therapy for complicated focal IgAN can be decreased to reduce adverse events.

Updating the International IgA Nephropathy Prediction Tool for use in children.

Although IgA nephropathy (IgAN) is a common cause of glomerulonephritis in children, the absence of a method to predict disease progression limits personalized risk-based treatment decisions. The adult International IgAN Prediction Tool comprises two validated Cox survival models that predict a 50% decline in estimated glomerular filtration rate (eGFR) or end stage kidney disease (ESKD) using clinical risk factors and Oxford MEST histology scores. Here, we updated the Prediction Tool for use in children using a multiethnic international cohort of 1,060 children with IgAN followed into adulthood. The updated pediatric Prediction Tool had better model fit than the original adult tool with lower Akaike Information Criterion, higher R2D and similar C-statistics. However, calibration showed very poor agreement between predicted and observed risks likely due to the observed disease trajectory in children. Therefore, the Tool was updated using a secondary outcome of a 30% reduction in eGFR or ESKD, resulting in better R2D (30.3%/22.2%) and similar C-statistics (0.74/0.68) compared to the adult tool but with good calibration. The trajectory of eGFR over time in children differed from adults being highly non-linear with an increase until 18 years old followed by a linear decline similar to that of adults. A higher predicted risk was associated with a smaller increase in eGFR followed by a more rapid decline, suggesting that children at risk of a 30% decrease in eGFR will eventually experience a larger 50% decrease in eGFR when followed into adulthood. As such, these two outcomes are analogous between pediatric and adult Prediction Tools. Thus, our pediatric Prediction Tool can accurately predict the risk of a 30% decline in eGFR or ESKD in children with IgAN.

Prognosis and acute complications at the first onset of idiopathic nephrotic syndrome in children: a nationwide survey in Japan (JP-SHINE study).

BACKGROUND: Information on the epidemiology of idiopathic nephrotic syndrome (INS) in children, complications of INS and the side effects of steroid therapy is scarce. METHODS: The Japanese Pediatric Survey Holding Information of Nephrotic Syndrome, a nationwide cohort study, was conducted by the Japanese Study Group of Renal Disease in Children and enrolled 2099 children with newly diagnosed INS between 1 January 2010 and 31 December 2012. We conducted a follow-up study of the complications during the first onset and the patients' prognosis in this cohort. RESULTS: We obtained follow-up data on 999 children (672 males) with a median age at onset of 4.5 years [interquartile range (IQR) 2.8-9.4] and a median follow-up period of 4.1 years (IQR 2.5-5.1). At the first onset, 24% of patients experienced severe acute kidney injury (AKI), defined as a serum creatinine increase to a level two or more times the baseline. On logistic regression analysis, age, hematuria, severe hypoalbuminemia (serum albumin <1.0 g/dL) and severe bacterial infection were not independent factors, but female sex {hazard ratio [HR] 1.5 [95% confidence interval (CI) 1.1-1.7]} and hypertension [HR 4.0 (95% CI 2.6-6.0)] were significantly related to AKI. During the observation period, ocular hypertension requiring treatment occurred in 17.4% of patients, among which 0.4% received surgical treatment. Progression to frequently relapsing nephrotic syndrome/steroid-dependent nephrotic syndrome in 3 years was seen in 44.2% of the patients and was shown by the Cox regression analysis to be significantly related to younger age and days until remission at the first episode, but not to sex, hematuria, the minimum serum albumin level or AKI. Two patients died during the observation period. One patient showed progression to end-stage kidney disease. CONCLUSION: Based on the results of a multicenter questionnaire survey, the overall survival and renal survival rates were found to be excellent. However, proper management of complications, particularly in AKI and ocular hypertension, is mandatory.

Non-immunosuppressive therapies for childhood IgA nephropathy.

IgA nephropathy (IgAN) is the most common chronic primary glomerulonephritis in both children and adults, and 20-30% of patients with persistent hematuria/proteinuria progress to kidney failure within 20 years. In Japan, most cases of childhood IgAN are detected by school screening programs during the early onset of the disease when hematuria/proteinuria are asymptomatic and kidney function is normal. Therefore, it is possible to follow the detailed clinical course and appropriate therapeutic interventions from early onset of the disease. Data on non-immunosuppressive therapies for children with IgAN are highly limited. The Japanese Pediatric IgA Nephropathy Treatment Study Group was organized in 1989 to conduct clinical trials and accumulate data on treatments for childhood IgAN. In this review, we focus on non-immunosuppressive therapies, notably with renin-angiotensin-aldosterone system (RAAS) inhibitors for childhood IgAN and related clinical trials conducted primarily in Japan. We also describe the anti-inflammatory and antiproteinuric effects of RAAS inhibitors in IgAN, differences in treatment regimens because of the acute and active pathological features of childhood IgAN, adverse events of RAAS inhibitors, other non-immunosuppressive treatment options, and future directions.

Clinicopathological significance of glomerular capillary IgA deposition in childhood IgA nephropathy.

BACKGROUND: IgA nephropathy (IgAN) is characterized by predominant mesangial IgA deposition. Some patients with IgAN demonstrate IgA deposition in glomerular peripheral capillaries (cap-IgA). The clinicopathological significance of cap-IgA remains incompletely investigated in children. METHODS: We retrospectively analyzed 503 consecutive cases of biopsy-proven childhood IgAN between July 1976 and June 2013 to compare clinical and pathological features between IgAN patients with and without cap-IgA. RESULTS: Among the 503 patients, 30 (6.0%) had cap-IgA. We found significant differences in proteinuria (2.0 vs. 0.5 g/day/m2, p < 0.0001), time from onset to kidney biopsy (2.2 vs. 8.3 months, p < 0.0001), and rate of proteinuria remission after treatment (23.3% vs. 48.0%, p = 0.007) between both groups. Pathological analysis revealed significant differences in M1 (83.3% vs. 56.0%, p = 0.002), ratio of subendothelial electron dense deposits (EDDs, 58.6% vs. 16.5%, p < 0.0001) and subepithelial EDDs (48.3% vs. 16.5%, p = 0.0001), and glomerular basement membrane (GBM) lysis (58.6% vs. 27.1%, p = 0.0006) between both groups. More than half of cap-IgA patients (17/30, 56.7%), whereas only 26.2% of non-cap-IgA patients (124/473), were treated with immunosuppressive treatments. Six of 30 cases (20%) with cap-IgA reached glomerular filtration rate (GFR) categories G3a-G5 (estimated GFR < 60 ml/min/1.73 m2) at most recent observation (mean observation period: 7.0 ± 4.0 years). According to Kaplan-Meier analysis, patients with cap-IgA had significantly lower kidney survival curves than non-cap-IgA patients (72.8% vs. 97.2% at 10 years, p < 0.0001). CONCLUSIONS: Cap-IgA is associated with acute inflammation with GBM changes, resulting in refractory heavier proteinuria. Cap-IgA may represent a poor prognostic factor.

Utility of glomerular Gd-IgA1 staining for indistinguishable cases of IgA nephropathy or Alport syndrome.

BACKGROUND: Pathological findings in Alport syndrome frequently show mesangial proliferation and sometimes incidental IgA deposition, in addition to unique glomerular basement membrane (GBM) changes including thin basement membrane and/or lamellation. However, similar GBM abnormalities are also often observed in IgA nephropathy. Both diseases are also known to show hematuria, proteinuria, and sometimes macrohematuria when associated with viral infection. Therefore, it can be difficult to make a differential diagnosis, even based on clinical and pathological findings. Some recent articles demonstrated that galactose-deficient IgA1 (Gd-IgA1)-specific monoclonal antibody (KM55) could potentially enable incidental IgA deposition to be distinguished from IgA nephropathy. METHODS: We performed comprehensive gene screening and glomerular Gd-IgA1 and type IV collagen α5 chain immunostaining for five cases with both IgA deposition and GBM changes to confirm that Gd-IgA1 can help to distinguish these two diseases. RESULTS: Four of the cases were genetically diagnosed with Alport syndrome (Cases 1-4) and one was IgA nephropathy with massive GBM changes, which had a negative gene test result (Case 5). In Cases 1-4, glomerular Gd-IgA1 deposition was not detected, although there was positivity for IgA in the mesangial area. In Case 5, glomerular Gd-IgA1 deposition was observed. CONCLUSION: Gd-IgA1 expression analysis could clearly differentiate these two disorders. This approach can be applied to identify these two diseases showing identical clinical and pathological findings.

Molecular mechanisms determining severity in patients with Pierson syndrome.

Null variants in LAMB2 cause Pierson syndrome (PS), a severe congenital nephrotic syndrome with ocular and neurological defects. Patients' kidney specimens show complete negativity for laminin ß2 expression on glomerular basement membrane (GBM). In contrast, missense variants outside the laminin N-terminal (LN) domain in LAMB2 lead to milder phenotypes. However, we experienced cases not showing these typical genotype-phenotype correlations. In this paper, we report six PS patients: four with mild phenotypes and two with severe phenotypes. We conducted molecular studies including protein expression and transcript analyses. The results revealed that three of the four cases with milder phenotypes had missense variants located outside the LN domain and one of the two severe PS cases had a homozygous missense variant located in the LN domain; these variant positions could explain their phenotypes. However, one mild case possessed a splicing site variant (c.3797 + 5G>A) that should be associated with a severe phenotype. Upon transcript analysis, this variant generated some differently sized transcripts, including completely normal transcript, which could have conferred the milder phenotype. In one severe case, we detected the single-nucleotide substitution of c.4616G>A located outside the LN domain, which should be associated with a milder phenotype. However, we detected aberrant splicing caused by the creation of a novel splice site by this single-base substitution. These are novel mechanisms leading to an atypical genotype-phenotype correlation. In addition, all four cases with milder phenotypes showed laminin ß2 expression on GBM. We identified novel mechanisms leading to atypical genotype-phenotype correlation in PS.

Crescentic IgA nephropathy in children.

OBJECTIVES: Crescentic IgA nephropathy (C-IgAN) is defined as IgAN with more than 50% of glomeruli showing crescents. C-IgAN in children is rare; we investigate in detail for the first time. METHODS: We retrospectively analyzed the 515 consecutive children who were newly diagnosed with biopsy-proven IgAN between June 1976 and May 2010. We compared clinical and pathological findings between C-IgAN and non-C-IgAN. RESULTS: Among 515 cases of childhood IgAN, 25 children (4.9%) had C-IgAN. Of these 25, 16 children (64%) were referred to hospitals by annual school screening. Clinical findings showed significant differences in gross hematuria (76 vs. 50%, p = .03), excretion of proteinuria (1.9 vs. 0.5 g/day/m2, p < .0001), eGFR (102 vs. 108 ml/min/1.73 m2, p = .03), and duration from onset to renal biopsy (4.0 vs. 8.0 months, p = .04) between groups. Pathological findings showed significant differences in M1 (88 vs. 55%, p = .02), E1 (83 vs. 53%, p = .008), and presence of tubular atrophy/interstitial fibrosis (88 vs. 53%, p < .0001) between groups. The 16 children with C-IgAN were treated with prednisolone and immunosuppressant. Four cases (16%) reached chronic renal failure (eGFR < 60) at the latest observation (mean observation period: 6.0 ± 3.6 years). Patients with C-IgAN had significantly lower renal survival curve than non-C-IgAN patients according to Kaplan-Meier analysis (77.1% vs. 92.6% at 13 years, p < .0001). Compared with previous reports, however, they had better renal outcome. CONCLUSIONS: We confirmed the importance of school screening to find C-IgAN. Although most crescents (mean: 98.1%) of C-IgAN were cellular/fibrocellular, and acute lesions were well modified with combination therapy, the presence of tubular atrophy in C-IgAN may be the reason for poorer prognosis.

Lisinopril versus lisinopril and losartan for mild childhood IgA nephropathy: a randomized controlled trial (JSKDC01 study).

BACKGROUND: Persistent proteinuria seems to be a risk factor for progression of renal disease. Its reduction by angiotensin-converting inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) is renoprotective. Our previous pilot study showed that 2-year lisinopril therapy is effective and safe for children with mild IgA nephropathy. When combined with ACEI and ARB, reported results are of greater decrease in proteinuria than monotherapy in chronic glomerulonephritis, including IgA nephropathy. To date, however, there have been no randomized controlled trials in children. METHODS: This is an open-label, multicenter, prospective, and randomized phase II controlled trial of 63 children with biopsy-proven proteinuric mild IgA nephropathy. We compared efficacy and safety between patients undergoing lisinopril monotherapy and patients undergoing combination therapy of lisinopril and losartan to determine better treatment for childhood proteinuric mild IgA nephropathy. RESULTS: There was no difference in proteinuria disappearance rate (primary endpoint) between the two groups (cumulative disappearance rate of proteinuria at 24 months: 89.3% vs 89% [combination vs monotherapy]). Moreover, there were no significant differences in side effects between the two groups. CONCLUSIONS: We propose lisinopril monotherapy as treatment for childhood proteinuric mild IgA nephropathy as there are no advantages of combination therapy. CLINICAL TRIAL REGISTRATION: Clinical trial registry, UMIN ID C000000006, https://www.umin.ac.jp .

Clinicopathological characteristics and renal outcomes of childhood-onset lupus nephritis with acute kidney injury: A multicenter study.

Objectives: Acute kidney injury (AKI) at onset of adult systemic lupus erythematosus (SLE) is a risk factor for end stage kidney disease (ESKD). However, data on childhood-onset lupus nephritis (LN) with AKI are scarce.Methods: We retrospectively reviewed the complete files of pediatric SLE patients from 1995 to 2010. All patients underwent kidney biopsy promptly after diagnosis.Results: Thirty-six patients (10 males and 26 females) were enrolled. Mean age at diagnosis and observation period were 11.6 ± 2.4 and 8.1 ± 4.4 years, respectively. Seven patients had AKI at onset of SLE. Compared with those without AKI, patients with AKI had significantly higher proportions of pathologically proliferative LN. Only one patient with AKI progressed to ESKD without complete recovery of renal function. Overall and renal survival rates were 100and 97.2%, respectively. There was no significant difference in estimated glomerular filtration rate at the final visit (85ml/min/1.73 m2 in the AKI group vs. 103.2 ml/min/1.73 m2 in the non-AKI group; p = .11).Conclusion: Our study demonstrated favorable renal outcomes in childhood-onset LN with AKI in the near to midterm period. Inducing complete remission may be important for preserving renal function.

Biallelic Mutations in Nuclear Pore Complex Subunit NUP107 Cause Early-Childhood-Onset Steroid-Resistant Nephrotic Syndrome.

The nuclear pore complex (NPC) is a huge protein complex embedded in the nuclear envelope. It has central functions in nucleocytoplasmic transport, nuclear framework, and gene regulation. Nucleoporin 107 kDa (NUP107) is a component of the NPC central scaffold and is an essential protein in all eukaryotic cells. Here, we report on biallelic NUP107 mutations in nine affected individuals who are from five unrelated families and show early-onset steroid-resistant nephrotic syndrome (SRNS). These individuals have pathologically focal segmental glomerulosclerosis, a condition that leads to end-stage renal disease with high frequency. NUP107 is ubiquitously expressed, including in glomerular podocytes. Three of four NUP107 mutations detected in the affected individuals hamper NUP107 binding to NUP133 (nucleoporin 133 kDa) and NUP107 incorporation into NPCs in vitro. Zebrafish with nup107 knockdown generated by morpholino oligonucleotides displayed hypoplastic glomerulus structures and abnormal podocyte foot processes, thereby mimicking the pathological changes seen in the kidneys of the SRNS individuals with NUP107 mutations. Considering the unique properties of the podocyte (highly differentiated foot-process architecture and slit membrane and the inability to regenerate), we propose a "podocyte-injury model" as the pathomechanism for SRNS due to biallelic NUP107 mutations.

Combination therapy with or without warfarin and dipyridamole for severe childhood IgA nephropathy: an RCT.

BACKGROUND: Two previous randomized controlled trials showed that treatment of severe childhood immunoglobulin A (IgA) nephropathy using prednisolone with azathioprine, heparin-warfarin, or dipyridamole prevented the increase of sclerosed glomeruli. Prednisolone alone, however, did not prevent further increase. These studies indicated the importance of immunosuppressants in the treatment. An additional pilot study using mizoribine instead of azathioprine enabled us to complete 2 years of combined regimen. It showed non-numerical inferior effectiveness compared with the azathioprine regimen. Further examination of the additional efficacy of warfarin and dipyridamole was required. METHODS: A randomized control trial of prednisolone and mizoribine with (group 1) or without (group 2) warfarin and dipyridamole was administered for treatment of 71 children with severe IgA nephropathy to evaluate the efficacy of additional warfarin and dipyridamole. RESULTS: Thirty of 34 patients (88.2%) in group 1, and 27 of 36 patients (75.0%) showed the disappearance of proteinuria as defined by early morning urinary protein to creatinine ratio of < 0.2 during the 2-year treatment period. The cumulative disappearance rate of proteinuria determined by the Kaplan-Meier method showed that the disappearance rate of proteinuria was significantly higher in group 1 than in group 2 (log-rank P = 0.04). There was no significant difference in pathological findings, but there was a tendency of increase of global sclerosis in group1 which might be related to warfarin. Most of the adverse effects were related to prednisolone, but fortunately transient. CONCLUSIONS: The balance between minimal benefits of warfarin/dipyridamole and potential adverse effects may be in favor of avoiding them in children with IgA nephropathy.

Study protocol: high-dose mizoribine with prednisolone therapy in short-term relapsing steroid-sensitive nephrotic syndrome to prevent frequent relapse (JSKDC05 trial).

BACKGROUND: Eighty percent of children with steroid-sensitive nephrotic syndrome (SSNS) relapse within 2 years and 40-50% patients show frequently-relapsing nephrotic syndrome (FRNS). Patients showing a relapse within 6 months after initial remission are at high risk of FRNS. Since frequent prednisolone treatment for FRNS induces severe prednisolone side effects, development of a treatment to prevent patients from shifting to FRNS is desirable. Mizoribine is an immunosuppressive drug with fewer side effects than prednisolone. Recent studies reported the efficacy of high-dose mizoribine in children with FRNS. METHODS/DESIGN: We conduct a multicenter, open, randomized controlled trial to investigate the efficacy and safety of standard prednisolone plus high-dose mizoribine therapy in children with SSNS showing a relapse within 6 months after an initial remission. Patients are allocated to either standard prednisolone alone treatment group, or standard prednisolone plus high-dose mizoribine group. For the former group, mizoribine is administered at a dose of 10 mg/kg/day once daily and continued for 2 years. The primary endpoint is the duration to frequent relapse. DISCUSSION: The results provide important data on use of high-dose mizoribine to prevent SSNS patients from shifting to FRNS. Since blood concentrations of mizoribine have not been investigated in detail until now, there is a possibility that mizoribine is underestimated in favor of other immunosuppressive drugs. In future, high-dose mizoribine therapy may lead to prevention of relapse in children at high risk of FRNS, and to decreased total dose of prednisolone. TRIAL REGISTRATION: UMIN000005103 , (Prospectively registered 1st March 2011).

Aberrant Smad3 phosphoisoforms in cyst-lining epithelial cells in the cpk mouse, a model of autosomal recessive polycystic kidney disease.

Cystic epithelia acquire mesenchymal-like features in polycystic kidney disease (PKD). In this phenotypic alteration, it is well known that transforming growth factor (TGF)-ß/Smad3 signaling is involved; however, there is emerging new data on Smad3 phosphoisoforms: Smad3 phosphorylated at linker regions (pSmad3L), COOH-terminal regions (pSmad3C), and both (pSmad3L/C). pSmad3L/C has a pathological role in colorectal cancer. Mesenchymal phenotype-specific cell responses in the TGF-ß/Smad3 pathway are implicated in carcinomas. In this study, we confirmed mesenchymal features and examined Smad3 phosphoisoforms in the cpk mouse, a model of autosomal recessive PKD. Kidney sections were stained with antibodies against mesenchymal markers and domain-specific phospho-Smad3. TGF-ß, pSmad3L, pSmad3C, JNK, cyclin-dependent kinase (CDK) 4, and c-Myc were evaluated by Western blotting. Cophosphorylation of pSmad3L/C was assessed by immunoprecipitation. α-Smooth muscle actin, which indicates mesenchymal features, was expressed higher in cpk mice. pSmad3L expression was increased in cpk mice and was predominantly localized in the nuclei of tubular epithelial cells in cysts; however, pSmad3C was equally expressed in both cpk and control mice. Levels of pSmad3L, JNK, CDK4, and c-Myc protein in nuclei were significantly higher in cpk mice than in controls. Immunoprecipitation showed that Smad3 was cophosphorylated (pSmad3L/C) in cpk mice. Smad3 knockout/cpk double-mutant mice revealed amelioration of cpk abnormalities. These findings suggest that upregulating c-Myc through the JNK/CDK4-dependent pSmad3L pathway may be key to the pathophysiology in cpk mice. In conclusion, a qualitative rather than a quantitative abnormality of the TGF-ß/Smad3 pathway is involved in PKD and may be a target for disease-specific intervention.

IgA nephropathy with presentation of nephrotic syndrome at onset in children.

BACKGROUND: Despite a low incidence, nephrotic syndrome (NS) can present with IgA nephropathy (IgAN). The clinical characteristics and long-term outcomes of pediatric patients with IgAN presenting with NS (NS-IgAN) at onset have not been fully elucidated. METHODS: We retrospectively analyzed 426 patients, and compared clinical and pathological (Oxford) findings between those with NS-IgAN and those with non-NS-IgAN. RESULTS: Among 426 patients, 30 (7.0 %) had NS-IgAN. Logistic analyses showed that male sex (OR: 7.6, p = 0.0002), M1 (OR: 10.3, p = 0.002), and E1 (OR: 15.2, p = 0.0001) were significantly related to NS. The mean observation period was 6.2 ± 3.2 years. Although NS-IgAN was associated with significantly lower renal survival than non-NS-IgAN according to Kaplan-Meier analysis (p = 0.02), renal survival of NS-IgAN was good (92.4 % at 10 years). The most significant prognostic factor for renal survival was remission of proteinuria after treatment, and NS at onset is also a significant prognostic factor for renal survival after adjusting for remission of proteinuria. Twenty children with NS-IgAN were treated with prednisolone alone, or prednisolone and immunosuppressant. Remission of proteinuria occurred in 21 patients. Three cases of NS-IgAN progressed to stage III-V chronic kidney disease at the most recent observation. They all demonstrated heavy proteinuria after the 2-year initial treatment. The significant factor for persistent proteinuria at 5 years was S1 in NS-IgAN. CONCLUSIONS: The most significant factor for renal survival was responsiveness to treatment, not NS itself. As modifiable acute lesions are the dominant pathological findings in NS-IgAN, histological improvements achieved by appropriate treatments can result in a favorable prognosis.