Koji Sakuraya

Evaluation of kidney dysfunction and angiotensinogen as an early novel biomarker of intrauterine growth restricted offspring rats

Background:Few studies have addressed the growing concerns of chronic kidney diseases in children with intrauterine growth restriction (IUGR). Therefore, the purpose of this study was to evaluate long-term kidney dysfunction and determine if urinary angiotensinogen (AGT) was suitable as a novel early biomarker for kidney dysfunction in IUGR offspring.Methods:Pregnant rats underwent bilateral uterine artery ligation, and as a control group, sham surgeries were performed.Results:The birth weight was reduced, the urinary AGT to creatinine ratio was significantly higher at week 20, and urinary protein levels were significantly higher at week 32 in IUGR rats than in control rats. On the other hand, the histological findings at week 32 revealed long-term kidney dysfunction, more severe glomerulosclerosis, and greater glomerular diameters in IUGR rats. Moreover, AGT mRNA expression and immunohistological staining were significantly increased in IUGR rats; this suggests that the intrarenal renin–angiotensin system (RAS) contributes to renal dysfunction of IUGR offspring.Conclusion:Urinary AGT elevation prior to urinary protein levels suggests that AGT is an early biomarker. At week 32, kidney dysfunction was severe in IUGR rats and intrarenal RAS appeared to be one of the causes.

The Synergistic Effect of Mizoribine and a Direct Renin Inhibitor, Aliskiren, on Unilateral Ureteral Obstruction Induced Renal Fibrosis in Rats

PURPOSE Renal fibrosis, the major histopathological change in various renal disorders, is closely related to renal dysfunction. Unilateral ureteral obstruction is a well established model of experimental renal disease that results in tubulointerstitial fibrosis. Previous studies showed that aliskiren and mizoribine ameliorated unilateral ureteral obstruction induced renal fibrosis. However, to our knowledge the protective effect of combination therapy with aliskiren and mizoribine against renal fibrosis is unknown. We investigated the synergistic effects of aliskiren and mizoribine combination therapy on unilateral ureteral obstruction induced fibrosis in rats. MATERIALS AND METHODS Male Sprague Dawley® rats underwent unilateral ureteral obstruction followed by aliskiren and/or mizoribine treatment. Kidney samples were fixed for histopathology and immunohistochemistry of myofibroblasts (α-SMA) and macrophages (ED-1). Real-time quantitative reverse transcription-polymerase chain reaction was performed to measure α-SMA, TGF-β1, osteopontin, MCP-1 and renin expression. RESULTS After unilateral ureteral obstruction the tubular dilatation, interstitial volume and α-SMA expression scores were significantly decreased by combination therapy compared with monotherapy with aliskiren or mizoribine. Combination therapy caused a significant decrease in the number of ED-1 positive cells and in TGF-β1 gene expression compared with monotherapy with either drug (each p <0.05). Combination therapy also decreased OPN and MCP-1 gene expression (p <0.05). CONCLUSIONS Aliskiren and mizoribine combination therapy provides increased renal protection against renal fibrosis and unilateral ureteral obstruction induced inflammation.

Synergistic protective effects of mizoribine and angiotensin II receptor blockade on cyclosporine A nephropathy in rats

Background:Chronic cyclosporine A (CsA) nephrotoxicity is manifested by renal dysfunction, progressive histopathological kidney lesions characterized by afferent arteriolopathy, and tubulointerstitial fibrosis. In addition to the direct toxic effect of CsA, many other etiological factors such as angiotensin II, transforming growth factor (TGF)-β, and macrophage infiltration are involved in this pathogenesis. This study investigated the hypothesis that concomitant administration of mizoribine (MZR) and angiotensin II receptor blockade (ARB) may prevent CsA nephrotoxicity in rats.Methods:Sprague-Dawley male rats were divided into the following seven groups: group 1, treated with CsA; group 2, treated with CsA + MZR; group 3, treated with CsA + valsartan (Val); group 4, treated with CsA + MZR + Val; group 5, treated with MZR; group 6, treated with Val; and group 7, controls (n = 5 each). Renal histopathology and the effect of CsA-induced nephrotoxicity on inflammatory mediators were evaluated.Results:Results of this study demonstrated that ARB administration significantly decreased arteriolopathy and that in comparison with monotherapy, concomitant administration of MZR and ARB further decreased arteriolopathy, fibrosis, macrophage infiltration, and TGF-β1 mRNA expression associated with CsA nephrotoxicity.Conclusion:These findings indicate that MZR and ARB combination treatment provides synergistic protective effects against chronic CsA nephrotoxicity.

Effect of insulin‐like growth factor‐I during the early postnatal period in intrauterine growth‐restricted rats

Insulin‐like growth factor‐I (IGF‐I) is essential for perinatal growth and development; low serum IGF‐I has been observed during intrauterine growth restriction (IUGR). We investigated the effects of recombinant human (rh) IGF‐I in IUGR rats during the early postnatal period.

Should mycophenolate mofetil be administered prior to cyclosporine A as a steroid-sparing agent to children with steroid-dependent nephrotic syndrome?

Sir, We read with great interest the review article titled, BMycophenolate mofetil for sustained remission in nephrotic syndrome^ by Querfeld et al. [1]. Based on the recommendations in the recent clinical practice guidelines, the authors conclude that mycophenolate mofetil (MMF) is a valuable steroid-sparing agent that does not exert a nephrotoxic effect on children with frequent-relapsing nephrotic syndrome (FRNS) or steroid-dependent nephrotic syndrome (SDNS). They also recommend the administration of MMF for several years to achieve sustained remission of nephrotic syndrome (NS) because many studies have reported rapid relapse of NS after MMF discontinuation. Although recent randomized controlled trials have demonstrated that MMF is less effective than cyclosporine A (CsA), currently, there is no consensus regarding the firstline steroid-sparing agent for children with FRNS or SDNS. In this regard, we previously reported in Pediatric Nephrology that MMF can be an alternative treatment for patients with chronic nephrotoxicity who have undergone long-term CsA treatment [2]. In contrast, severe infections may develop in some children with FRNS or SDNS who receive such immunosuppressive agents for a long period, resulting in NS relapse and hospitalization. However, there is limited information regarding the adverse events in these patients at the time of febrile infections. Based on our experience at a single center, we would like to comment on the risk factors for NS relapse and hospitalization during the course of infections in children with SDNS who received steroid-sparing agents, such as MMF and CsA. Between 2005 January and 2016 December, we retrospectively reviewed 203 episodes of febrile infections (> 37.5 °C) in 83 patients with childhood-onset SDNS (median age, 6.9 years) who were treated with various immunosuppressive agents (CsA in 106, MMF in 71, mizoribine [MZR] in 27, and cyclophosphamide [CPM] in 9 patients) at Saitama Children’s Medical Center [3]. Of the 203 episodes (47 due to influenza virus, 7 due to streptococcal infections, 3 due to adenovirus, 3 due to mycoplasma pneumoniae, 12 due to others, and 131 due to unknown pathogens) NS relapse and hospitalization because of severe infection was observed in 15 (7.4%) and 15 patients (7.4%), respectively. There were no differences in the clinical characteristics, such as age at febrile infection, and use of CsA or CPM between the patients with and without NS relapse. However, the use of MZR (40 vs. 11%, p < 0.01) and prevalence of influenza virus infection (47 vs. 21%, p < 0.05) were significantly higher in patients with NS relapse than in those without relapse. However, the use of MMF in patients with NS relapse was significantly lower than in those without relapse (7 vs. 32%, p < 0.05). There were no differences in the clinical characteristics, such as use of MZR or CPM, and prevalence of influenza virus infection between hospitalized and non-hospitalized patients. However, the use of CsA (20 vs. 50%, p < 0.05) and mean age at febrile infection (6.8 vs. 8.2 years, p < 0.05) were significantly lower in patients requiring hospitalization than in those without hospitalization. In addition, the use of MMF was significantly higher in hospitalized patients than in nonhospitalized patients (53 vs. 28%, p < 0.05). In this retrospective study of 83 children with SDNS who received various immunosuppressive agents at the time of febrile infections, MMF inhibited NS relapse more effectively than MZR. Moreover, compared to the use of CsA, the use of MMF at the time of febrile infections was * Shuichiro Fujinaga f_shuich@d2.dion.ne.jp

Single infusion of low-dose ofatumumab in a child with complicated nephrotic syndrome with anti-rituximab antibodies

Sir, We read with great interest the article published in Pediatric Nephrology entitled BOfatumumab for the treatment of childhood nephrotic syndrome^ by Wang et al. [1]. In their experience of five children with rituximab (RTX)-resistant complicated nephrotic syndrome (NS), four patients achieved partial or complete remission after completion of five infusions of high-dose ofatumumab (OFA) at an initial dose of 300 mg/1.73 m followed by five weekly doses of 2000 mg/ 1.73 m. In a study published slightly earlier involving two children with complicated NS who were unable to complete RTX treatment due to severe infusion reactions (IR), Vivarelli et al. reported that a single infusion of OFA (750 mg/1.73 m) may be a therapeutic option for managing severe forms of NS in children with allergy to RTX [2]. Unfortunately, antirituximab antibodies (ARA) were not measured in either study, despite the possibility that the development of ARA may be associated with decreased efficacy and severe adverse events. Herein, we report, to the best of our knowledge, the first case of a child with complicated RTX-resistant NS with ARA who was successfully treated with a single infusion of low-dose OFA (300 mg/m), with the patient not experiencing IR to OFA as opposed to RTX. A Japanese boy was admitted to another hospital at 15 months of age for treatment of idiopathic NS. Although initial treatment with high-dose prednisolone resulted in complete remission of proteinuria, the patient developed complicated steroid-dependent NS that required eight infusions of RTX in combination with long-term cyclosporine (CsA) and steroids. After experiencing 13 relapses of NS during CsA treatment, he was referred to our hospital at the age of 5 years. Renal biopsy at that age showed minimal change disease with chronic CsA nephrotoxicity, which prompted us to switch the immunosuppressive agent from CsA to mycophenolate mofetil. However, despite three additional infusions of RTX (375 mg/1.73 m), CD19-positive cells became detectable (>1% of total lymphocytes) within 1 month following each RTX infusion and high-dose steroid dependency persisted, which led to the re-introduction of CsA treatment. Furthermore, although the patient had received premedication with methylprednisolone, acetaminophen, and antihistamine 30 min prior to each RTX treatment, immediate severe IR (grade 3) with tachycardia and wheeze developed just after the initiation of the fourth RTX infusion at our hospital (a total of 12 infusions), leading to its discontinuation. At that time, serum ARA levels measured using an enzyme-linked immunosorbent assay increased to 580 ng/mL. Thus, after obtaining approval from the ethics committee of our center (approval number 2016-99-41) and written parental informed consent for the use of OFA, we administered a single dose of OFA to the patient during a proteinuria-free period. As per the therapeutic protocol, low-dose OFA (300 mg/m) was diluted in 1 L of saline, and the infusion rate was steadily increased for completion within 12 h: 12 mL/h for the first 30 min followed by 25mL/h 31–60min, 50mL/h 61–90min, and 100mL/h up to the end of the 12-h period. Although the premedication schedule was utilized without modifications, IR did not develop during OFA infusion. The patient was first able to withdraw from prednisolone without any NS relapse at 3 months after OFA infusion and remained in complete remission under monotherapy with CsA 5 months later. Similar to our observations on this patient, Ahn et al. described the development of ARA in two Korean children with NS who experienced severe IR and did not achieve B-cell depletion after repeated RTX infusions [3]. Although these authors suggested the use of more humanized anti-CD20 monoclonal antibodies as an alternative, there is no consensus * Shuichiro Fujinaga f_shuich@d2.dion.ne.jp

Repeated administrations of rituximab along with steroids and immunosuppressive agents in refractory steroid-resistant nephrotic syndrome

BackgroundA recent randomized control trial in children with steroid-resistant nephrotic syndrome revealed that two doses of rituximab did not reduce proteinuria.Case characteristicsA 14-month-old boy developed refractory steroid-resistant nephrotic syndrome due to focal segmental glomerulosclerosis.ObservationThe patient achieved complete remission 11 months after disease onset following eight doses of rituximab combined with steroids and cyclosporine.MessageLong-lasting B cell depletion with repeated rituximab administrations may be required to achieve complete remission in patients with steroid-resistant nephrotic syndrome and massive proteinuria.

Initial prednisolone dosing for the first relapse of steroid-sensitive nephrotic syndrome in Japanese children

Sir, We read with great interest the article titled, BInduction prednisone dosing for childhood nephrotic syndrome^ by Sibley et al. [1]. In this retrospective study including 92 Canadian children with nephrotic syndrome (NS) who had received various doses of prednisone during the initial episode, the authors concluded that cumulative doses of ≤ 2000 mg/m should be avoided based on poor outcomes compared with high-dose regimens. In Japanese children with new-onset NS weighing < 30 kg, we previously reported in Pediatric Nephrology that body weight (BW)-based dosing regimens (prednisolone, 2 mg/kg/day for 4 weeks and then 1.3 mg/kg every other day for 4 weeks) led to significantly worsening relapse outcomes over 2 years compared with body surface area-based dosing regimens (cumulative dose, 2240 mg/m; 60 mg/m/day for 4 weeks and then 40 mg/m every other day for 4 weeks) [2]. The poor prognosis of BWbased dosing regimens also probably was due to the underdosing effect, particularly in children weighing < 30 kg. Although induction steroid regimens for new-onset NS may be established after recent well-designed randomized clinical trials (RCTs), the optimal prednisolone dose for NS relapse remains unclear. Based on our retrospective analysis, we wish to comment on the initial prednisolone dosing for the first relapse of steroid-sensitive NS. Total 49 NS patients with first relapse (41 boys, 8 girls; median age, 4.9 years) observed for > 12 months at Saitama Children’s Medical Center (2005–2016) were enrolled in this study; patients with steroid-resistant NS, history of steroid-sparing agent use, or BW > 30 kg were excluded. As per therapeutic protocol, new-onset NS was treated with prednisolone (60 mg/m/day; maximum 60 mg) for 4 weeks followed by 40 mg/m (maximum 40 mg) every other day for 4 weeks. Relapse was treated with the same dose of prednisolone administered at NS onset (even if BW at NS relapse was increased compared with BW at NS onset) until proteinuria disappeared, observed during three consecutive days. Thereafter, prednisolone was administered on alternate days, and the dose was tapered off within 6 months by reducing by 5–10 mg every 2–4 weeks. Based on the initial prednisolone dosing for the first relapse, the 49 patients were classified into three groups: low (≤ 1.8 mg/kg/day, N = 13)-, middle (1.8–2.0 mg/kg/ day, N = 14)-, and high (> 2.0 mg/kg/day, N = 22)-dose groups. There were no significant differences among the three groups regarding patient characteristics, such as sex, median urinary protein-to-creatinine ratio at first relapse (3.0, 5.3, and 4.9 for low-, middle-, and high-dose groups, respectively), median time to first relapse (107, 92.5, and 89 days, respectively), and median age at first relapse (5.1, 3.8, and 4.3 years, respectively). After initiation of steroid treatment for the first relapse, there were no significant differences among the three groups regarding the clinical course, such as median time until complete remission (7.0, 7.5, and 7.0 days, respectively), and the rate of progression to frequently relapsing NS (38.5%, 42.8%, and 54.5%, respectively). During the treatment period for the first relapse, steroid-induced glaucoma requiring eye drops developed in 6 of the 49 patients (12.2%). The rate of glaucoma development in the low-dose group was low compared with that in the middleand high-dose groups (7.7%, 14.3%, and 13.6%, respectively). In a retrospective study including 87 relapses in 50 children with steroid-sensitive NS, Raja et al. reported that a low-dose prednisolone regimen (1 mg/kg/day, maximum 40 mg/day) was successful in achieving complete remission in 77% of the relapse cases without adversely affecting the subsequent relapse rate [3]. Furthermore, the * Shuichiro Fujinaga f_shuich@d2.dion.ne.jp

Impaired nephrogenesis in neonatal rats with oxygen-induced retinopathy

Preterm neonates are born while nephrogenesis is ongoing, and are commonly exposed to factors in a hyperoxic environment that can impair renal development. Oxidative stress has also been implicated in the development of retinopathy of prematurity (ROP). The rat model of oxygen‐induced retinopathy (OIR) is the most clinically relevant model of ROP because its biologic features closely resemble those of ROP in preterm infants. We investigated impaired renal development in a rat model of OIR.