Minor Glomerular Abnormalities Research Articles

Effect of Proprotein Convertase Subtilisin/Kexin Type 9 Inhibition on Podocytes in Mouse Nephrotic Syndrome

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is known to play a crucial role in dyslipidemia, and an increase in serum PCSK9 levels has also been reported in patients with nephrotic syndrome (NS). However, the specific effects of PCSK9 in kidney disease and the therapeutic potential of targeting PCSK9 in NS remain elusive. We thus investigated the effects of evolocumab (EVO) in mice with adriamycin (ADR)-induced NS. Male BALB/c mice were divided into the following 4 groups: Control, N = 11; EVO (monoclonal antibody for PCSK9), N = 11; ADR, N = 11; and ADR+EVO, N = 11. We also performed in vitro experiments using immortalized murine podocyte cells to validate the direct effects of PCSK9 on podocytes. EVO decreased urinary albumin levels and ameliorated podocytopathy in mice with ADR nephropathy. Further, EVO suppressed the Nod-like receptor protein 3 (NLRP3) inflammasome pathway in podocytes. PCSK9 expression upregulated CD36, a scavenger receptor of oxidized low-density lipoprotein (Ox-LDL), which in turn stimulated the absorption of Ox-LDL in vitro. EVO downregulated CD36 expression in podocytes both in vitro and in vivo. Immunofluorescence staining analysis reveals that CD36 and PCSK9 colocalized in the glomerular tufts of mice with ADR nephropathy. In the patients with focal segmental glomerulosclerosis, the CD36+ area in glomerular tufts increased compared with those diagnosed with minor glomerular abnormalities. This study revealed that EVO ameliorated mouse ADR nephropathy through the regulation of CD36 and NLRP3 inflammasome signaling. EVO treatment represents a potential therapeutic strategy for human NS.

#5400 CLINICAL PROFILE, MICROSCOPIC FEATURES AND OUTCOMES OF PATIENTS WITH MINOR GLOMERULAR ABNORMALITIES AT NKTI: A 10-YEAR DESCRIPTIVE CROSS-SECTIONAL STUDY

Abstract Background and Aims Minor Glomerular Abnormality (MGA) is a kidney biopsy diagnosis characterized by the presence of minor structural abnormalities which, are not sufficient to be classified under the other known glomerular diseases. Although usually considered a benign renal problem, few literatures mentioned it may cause deterioration of kidney function in the long term. The objective of this study is to describe the clinical profile, microscopy findings, treatment outcome and renal survival of patients diagnosed with Minor Glomerular Abnormalities in NKTI from 2005 to 2015. Method This is a Retrospective, Descriptive, Cross-sectional study which included 190 patients who were diagnosed with MGA. Demographic, clinical profile, CKD classification and treatment outcomes were presented using descriptive statistics while renal survival was analysed using Fisher's Exact Test. Based on the level of proteinuria and serum creatinine, treatment outcomes of the patients were classified as either with (1) complete response [if with reduction in proteinuria to ≤ 300 mg/day (</ = 0.3 g/day) and a creatinine clearance ≥ 80 ml/min with no reduction from baseline] (2) partial response [proteinuria between 300 mg and 3 g/day OR by at least 50% from baseline level and with no deterioration in creatinine clearance], (3) relapse[patients whom (a) after a complete response to treatment (baseline proteinuria ≤ 300 mg/day), there is an increase in proteinuria to ≥ 1.0 g/day or (b) after a partial response (baseline proteinuria between 300 mg and 3 g/day), there is an increase in proteinuria to ≥ 3 g/day or increase in proteinuria by ≥ 50%, or (c) after a partial response (baseline proteinuria > 3 g/day), there is an increase in proteinuria by ≥ 50%], or (4) unsatisfactory response to treatment if complete or partial response is not met. Renal survival was assessed by classifying the renal status of the patients as either with (1) Normal or Mildly Decreased GFR [CKD 1-2] or (2) with moderately decreased kidney function to renal failure [CKD 3-5]. Results The mean age of the MGA patients at diagnosis was 37 years old. Of the 190 subjects of this study, 53.68% were female and 73.16% has no comorbidities. Proteinuria was the most common reason for consult (66.32%), followed by hematuria (38.42%) and worsening renal function (14.21%). Most of the patients had Nephrotic Syndrome (39%) before biopsy. The top three Electron Microscopy findings were Minimal Change Disease (24.4%) Segmental Podocyte Foot Processes Effacement (True MGA) at 27.4% and Thin Basement Membrane Disease (22.6%). At one year and five years, 13.68% and 4.74% respectively have complete response to treatment while 22.10% and 13.15% respectively have either partial or unsatisfactory response to treatment. Eighty patients (86.02%) at one year and 33 patients (78.57%) at 5 years remain at CKD 1-2. When the renal survival of the True MGA and Non-MGA patients were compared using Fisher Exact Test, there was no significant difference between the two groups (p values of 0.080 at 1 year and 0.99 at 5 years). Conclusion Minimal Change Disease is the most common Electron Microscopy diagnosis. Majority have good renal survival, but few progressed to CKD 3-5. Survival between MGA and Non-MGA patients are similar.

Galactose-deficient IgA1 is Involved in IgA Deposition in Renal Grafts Biopsied One Hour after Kidney Transplantation.

Objective Asymptomatic renal immunoglobulin A (IgA) deposition occurs in healthy subjects, but its etiologic role in disease is unclear. Galactose-deficient IgA1 (Gd-IgA1) is involved in the pathogenesis of IgA nephropathy. We investigated Gd-IgA1 deposition in transplanted kidneys that were considered healthy showing subclinical latent IgA deposition one hour after transplantation. Methods A total of 723 transplanted kidney specimens biopsied 1 h after kidney transplantation from 2009 to 2016 at Nagoya Red Cross Hospital were examined. A total of 81 cases of IgA deposition were extracted, and 41 were ultimately studied. Double immunofluorescence staining for Gd-IgA1 and IgA was conducted to investigate the role of Gd-IgA1 in subclinical IgA deposition. Results Light microscopy findings for the 41 cases indicated only minor glomerular abnormalities. Immunofluorescence analyses revealed that all cases were positive for IgA. C3, IgG, and IgM positivity rates were 78.0%, 7.3%, and 60.9%, respectively. All 41 cases were positive for Gd-IgA1, which merged with IgA deposition in immunofluorescence double staining. IgA disappeared in 26 of 40 cases (65.0%) 1 year after kidney transplantation. In contrast, IgA redeposition was observed in three cases. Conclusion Gd-IgA1 was demonstrated in all transplanted kidneys, with latent IgA deposition noted in otherwise healthy kidneys. Deposition of Gd-IgA1 might indicate the initial stage of IgA nephropathy; however, additional factors, such as IgG deposition, are required for the ultimate development of IgA nephropathy.

Predictive significance of glomerular insulin receptor substrate-1 in patients with diabetic kidney disease

BackgroundIn rodents, glomerular expression of insulin receptor substrate 1 (IRS1) is decreased in diabetic kidney disease (DKD) and reduced associated functioning is involved in the development and progression of DKD. This study aimed to evaluate the significance of glomerular IRS1 expression in DKD patients, and investigated whether glomerular IRS1 expression can reflect renal pathology and predict renal outcomes. MethodsThis study included 10 patients who underwent renal biopsy and were diagnosed with DKD or minor glomerular abnormality (MGA). IRS1-positive cells were determined based on renal biopsy and immunostaining, and the associations of the number of these cells with baseline and prognostic parameters were analyzed. ResultsIRS1-positive cells were significantly decreased in DKD than in MGA. IRS1 positivity tended to be negatively correlated with global glomerulosclerosis and tubulointerstitial fibrosis. The rate of change in estimated glomerular filtration rate before and 12 months after renal biopsy was positively correlated to the number of IRS1-positive cells. Furthermore, a tendency towards negative correlation was observed between the number of glomerular IRS1-positive cells and the proteinuria. ConclusionsThis study shows the glomerular IRS1-positive cell count was significantly decreased in DKD, and that the degree IRS1 positivity was partially correlated with renal pathology and function.

Significance of podocyte DNA damage and glomerular DNA methylation in CKD patients with proteinuria.

The number of chronic kidney disease (CKD) patients is increasing worldwide, and it is necessary to diagnose CKD patients in earlier stages to improve their prognosis. Previously, in a study using human samples, we reported that DNA methylation and DNA damage in podocytes are potential markers for kidney function decline in IgA nephropathy; however, these candidate markers have not been adequately investigated in other glomerular diseases. Here, we report that the association of podocyte DNA damage and DNA methylation with eGFR decline and proteinuria differs depending on the type of glomerular disease. Patients diagnosed with minor glomerular abnormality (MGA, n = 33), membranous nephropathy (MN, n = 9) or diabetic nephropathy (DN, n = 10) following kidney biopsy at Keio University Hospital from 2015 to 2017 were included. In MGA patients, both podocyte DNA damage and glomerular DNA methylation were associated with the severity of proteinuria. In DN patients, podocyte DNA double-strand breaks (DSBs) and glomerular DNA methylation were associated with an eGFR decline. When patients with urinary protein levels of more than 1 g/gCr were examined, fewer podocyte DNA DSBs were detected in MN patients than in MGA patients, and the level of glomerular DNA methylation was lower in MN patients than in MGA or DN patients. These results indicate that investigating podocyte DNA DSBs and DNA methylation changes may be useful for understanding the pathogenesis of CKD with proteinuria in humans. This study suggested the association of podocyte DNA damage and subsequent DNA methylation with proteinuria in minor glomerular abnormalities (MGA) patients and those with eGFR declines in diabetic nephropathy (DN) patients, respectively.

PS-C26-12: SIGNIFICANCE OF PODOCYTE DNA DAMAGE AND GLOMERULAR DNA METHYLATION IN CKD WITH PROTEINURIA

Objective: Previously we have reported that altered DNA methylation is associated with DNA damage repair in podocytes in CKD, including diabetic nephropathy or IgA nephropathy (Cell Rep 2019, Sci Rep 2020). This study is aim to investigate the association of podocyte DNA damage and DNA methylation with clinical manifestations and renal prognosis in various types of kidney diseases, which has not been adequately investigated. Design and Method: Patients diagnosed with minor glomerular abnormalities (MGA, n = 33), membranous nephropathy (MN, n = 9) or diabetic nephropathy (DN, n = 10), following kidney biopsy at Keio University Hospital from 2015 to 2017 were included. We evaluated podocyte DNA double strand breaks (DSBs) using both long-distance PCR of nephrin gene and γH2AX immunostaining, and glomerular DNA methylation levels by immunostaining of 5mC, and examined the relationship between clinical parameters of patients, and DNA damage and methylation. Results: In MGA patients, both podocyte DNA damage and glomerular DNA methylation was associated with the amount of proteinuria. Moreover, glomerular DNA methylation was also associated with 3-year eGFR decline. We also examined in DN patients, in which podocyte DNA damage has been found to be involved in our previous study. It was demonstrated that podocyte DSBs were associated with a decline in eGFR over 6 months, whereas glomerular DNA methylation was associated with 2 year- and 3 year-eGFR decline. In addition, samples from MN patients were evaluated, in which activation of DNA repair pathways in the glomeruli has been suggested. Interestingly, the association of DNA DSBs or DNA methylation with proteinuria or kidney function was not indicated in MN. Conclusions: To our knowledge, this is the first study to demonstrate the possible association of podocyte DNA damage and glomerular DNA methylation with kidney function and its decline in MGA patients, whereas it was not observed in MN patients, despite a limitation of small sample size. Focusing on podocyte DNA damage and following DNA methylation changes may lead us to novel approaches to estimate renal prognosis in addition to traditional evaluation of renal biopsy as well as to develop novel therapeutic targets in specific types of CKD.

March hemoglobinuria progressed to acute kidney injury after kendo practice: a case report

BackgroundMarch hemoglobinuria is caused by a hemolytic mechanism due to transient hematuria after physical exercise which, although rare, may lead to acute kidney injury. We report a case of a patient with march hemoglobinuria induced by kendo, which was diagnosed by the presence of Berlin blue iron staining in the proximal tubules through renal biopsy.Case presentationA 15-year-old male complained of fever (37 °C), general malaise, and nausea after hard kendo sessions. Laboratory findings revealed indirect bilirubin dominant hyperbilirubinemia (total bilirubin 3.8 mg/dL), high lactate dehydrogenase (LDH), and acute kidney injury (serum creatinine: 3.11 mg/dL and estimated glomerular filtration rate: 26 mL/min/1.73m2). Urine test was positive for occult blood but without hematuria. Renal biopsy was performed to clarify the cause of renal injury, which showed minor glomerular abnormalities. Meanwhile, hemosiderin deposition was identified in the proximal tubules by Berlin blue iron staining, and lysosomes were observed to contain granular iron. In addition to clinical background of strenuous kendo exercise, renal biopsy led to a definitive diagnosis of march hemoglobinuria.ConclusionsMarch hemoglobinuria is a hemolytic disease that can occur after intense exercise, especially kendo. Considering its rarity due to the lack of critical symptoms, it is important to note that occult blood-positive findings may be indicative of march hemoglobinuria if the patient underwent strenuous exercise. Therefore, clinicians should be aware of this possibility to provide timely and appropriate treatment.

IgA vasculitis with transient glomerular hematuria, diarrhea, and pericarditis following COVID-19 mRNA vaccination in a young patient with possible pre-existing ulcerative colitis.

Exacerbations or de novo autoimmune/autoinflammatory disease have been reported after COVID-19 vaccination. A young male presented with cutaneous IgA vasculitis with glomerular hematuria, diarrhea and pericarditis following his second COVID-19 mRNA vaccination. He also showed positivity for proteinase 3 anti-neutrophil cytoplasmic antibody (PR3-ANCA) and anti-cardiolipin antibody. Skin biopsy was compatible to IgA vasculitis. His purpura subsided and hematuria spontaneously disappeared. Treatment with anti-inflammatory medications and prednisolone resolved the pericarditis. He had a history of persistent diarrhea, and colonic biopsies showed possible ulcerative colitis without vasculitis. Kidney biopsy after prednisolone therapy revealed minor glomerular abnormalities without any immune reactants and did not show vasculitis. After prednisolone treatment, PR3-ANCA decreased in a medium degree despite of improvement of symptoms and inflammatory data, suggesting that his PR3-ANCA may be associated with ulcerative colitis. The cause of the transient glomerular hematuria was unclear, however, it might be caused by focal glomerular active lesions (glomerular vasculitis) due to vaccine-induced IgA vasculitis with nephritis. This case highlights that COVID-19 mRNA vaccination can activate multiple autoimmune/autoinflammatory systems. The conditions might help us better understand the mutual mechanisms of the relevant disorders.

Clinical, pathological, and genetic characteristics of cases with asymptomatic proteinuria not manifesting nephrotic syndrome at onset: a single-center retrospective study.

Cases with asymptomatic proteinuria (ASP) not manifesting nephrotic syndrome often pathologically show focal segmental glomerulosclerosis (FSGS). However, characteristics of those cases had not been intensively studied so far. We retrospectively reviewed clinical, pathological, and genetic characteristics of 37 children (median age, 9.3years) who underwent renal biopsy for persistent isolated proteinuria (urine protein-to-creatinine ratio: UP/C, > 0.2g/g) between 2003 and 2019. Targeted next-generation sequencing (NGS) was utilized for all patients with FSGS, excluding those with secondary FSGS. At biopsy, all patients with FSGS (N = 14) had UP/C ≥ 0.5g/g and the median UP/C was significantly higher in those with FSGS than those with minor glomerular abnormalities (MGA) (N = 23) (1.49 vs. 0.53g/g, P < 0.001). Causative variants were found in seven patients with FSGS (TRPC6, WT1, ACTN4, and INF2 in 3, 2, 1, and 1 patient, respectively): all gene variants were in genes manifesting autosomal dominant inheritance mode. The proportion of the perihilar variant was significantly higher in the genetic FSGS patients than in the non-genetic FSGS patients (4/7 vs. 0/7, P < 0.05). Kaplan-Meier analysis showed that the renal survival rate after ASP diagnosis was significantly lower in the genetic FSGS patients than in the non-genetic FSGS and the MGA patients (P < 0.001). UP/C was a simple and useful predictive parameter for the diagnosis of FSGS. APS without nephrotic syndrome at onset may be associated with autosomal dominant causes of FSGS, especially in those with the perihilar variant.

Clinicopathologic Features of Mitochondrial Nephropathy

IntroductionThe clinicopathologic characteristics of nephropathy associated with mitochondrial disease (MD) remain unknown. We retrospectively analyzed a cohort of patients with proteinuria, decreased glomerular filtration rate, or Fanconi syndrome who had a genetic mutation confirmed as the cause of MD, defined as mitochondrial nephropathy.MethodsThis nationwide survey included 757 nephrology sections throughout Japan, and consequently, data on 81 cases of mitochondrial nephropathy were collected.ResultsThe most common renal manifestation observed during the disease course was proteinuria. Hearing loss was the most common comorbidity; a renal-limited phenotype was observed only in mitochondrial DNA (mtDNA) point mutation and COQ8B mutation cases. We found a median time delay of 6.0 years from onset of renal manifestations to diagnosis. Focal segmental glomerular sclerosis (FSGS) was the most common pathologic diagnosis. We then focused on 63 cases with the m.3243A>G mutation. The rate of cases with diabetes was significantly higher among adult-onset cases than among childhood-onset cases. Pathologic diagnoses were more variable in adult-onset cases, including diabetic nephropathy, nephrosclerosis, tubulointerstitial nephropathy, and minor glomerular abnormalities. During the median observation period of 11.0 years from the first onset of renal manifestations in patients with m.3243A>G, renal replacement therapy (RRT) was initiated in 50.8% of patients. Death occurred in 25.4% of the patients during the median observation period of 12.0 years. The median estimated glomerular filtration rate (eGFR) decline was 5.4 ml/min per 1.73 m2/yr in the cases, especially 8.3 ml/min per 1.73 m2/yr in FSGS cases, with m.3243A>G.ConclusionHere, we described the clinicopathologic features and prognosis of mitochondrial nephropathy using large-scale data.

Excretion Patterns of Urinary Sediment and Supernatant Podocyte Biomarkers in Patients with CKD.

Podocyte depletion causes glomerulosclerosis, and persistent podocyte loss drives progression to ESKD. Urinary sediment podocin (u-sed Pod) mRNA excretion and urinary supernatant podocalyxin (u-sup PCX) protein have been used to monitor disease activity in glomerular diseases. However, the differences in these markers among pathologies have not been investigated. We examined the roles of these markers in kidney diseases. From January 2013 to March 2016, early morning urine samples were collected from 12 healthy controls and 172 patients with kidney disease (n=15 patients with minor glomerular abnormality with mild proteinuria and/or microscopic hematuria, n=15 with minimal change nephrotic syndrome [MCNS], n=15 with membranous nephropathy [MN], n=60 with IgA nephropathy [IgAN], n=19 with crescentic GN [Cres GN], n=10 with lupus nephritis [LN], and n=38 with other kidney diseases). We examined u-sed Pod mRNA excretion, u-sup PCX protein, and the urinary protein-creatinine ratio (u-PCR). u-sed Pod mRNA excretion was significantly correlated with u-sup PCX protein (r=0.37, P<0.001). Both u-sed Pod mRNA excretion and u-sup PCX protein were significantly correlated with u-PCR (r=0.53, P<0.001 and r=0.35, P<0.001, respectively). Interestingly, u-sed Pod mRNA excretion was significantly increased in proliferative-type GN-including IgAN with extracapillary proliferative lesions, Cres GN, and LN class IV-and significantly correlated with the rate of crescent formation, whereas u-sup PCX protein was significantly increased only in those with MN and subepithelial dense deposit-type LN compared with controls. Higher u-sed Pod mRNA excretion and u-sup PCX protein were associated with proliferative-type GN, indicating podocyte detachment and subepithelial dense deposit-type GN, respectively. The results suggest that u-sed Pod mRNA excretion and u-sup PCX protein have usefulness for the diagnosis and measurement of disease activity with regard to glomerular diseases.

MO244CD47 BLOCKADE AMELIORATES AUTOIMMUNE VASCULITIS VIA THE EFFEROCYTOSIS OF NEUTROPHIL EXTRACELLULAR TRAPS*

Abstract Background and Aims Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is characterized by systemic necrotizing vasculitis in small vessels. The necrotic lesions consist of ANCA-mediated neutrophil extracellular traps (NETs) which represent a form of lytic cell death. The persistent NETs serve as autoantigens against ANCAs and cause organ damage in a vicious cycle. Considering dead cells are essentially cleared by phagocytic cells as a process of efferocytosis, why the NETs persist in tissue remains unclear. During efferocytosis, macrophages engulf apoptotic cells to prevent the leakage of intracellular components including toxic enzyme into the surrounding cells and these processes are regulated by the expression of CD47 as a “don’t eat me” signal. In this study, we hypothesized that ANCA-mediated NETs in AAV escape from efferocytosis via the up-regulation of CD47 and the persistent NETs amplify the disease. Method Human data: Human kidney biopsy specimens from patients with AAV and minor glomerular abnormality (MGA, as a case control) were subjected to immunohistochemistry (IHC) staining for CD47. In vitro: The expression of CD47 on neutrophils was evaluated by flow cytometry (FCM). Human neutrophils from healthy donor were treated with ANCA-IgGs from MPO-AAV patients or control IgGs. For the efferocytosis assay, macrophages were co-incubated with unstimulated, apoptotic, and ANCA-IgGs treated neutrophils in the presence of anti-CD47 monoclonal antibody (mAb) or a control antibody. The neutrophils were labeled with CFMDA cell tracker (fluorescent probe) and the efferocytosis was evaluated as neutrophil engulfed (CFMDA positive) macrophages using fluorescent microscopy. In vivo: Spontaneous crescentic glomerulonephritis-forming/Kinjoh (SCG/Kj) mice (8-week-old age) were treated with intraperitoneal injection of anti-CD47 mAb or a control antibody every 5 days for two weeks. The severity of glomerulonephritis was assessed by the levels of serum creatinine, haematuria, mRNA expression of pro-inflammatory genes, and histopathological findings. To address the immune response against the CD47 blockade, the titre of MPO-ANCA and the number of splenic cell subset was assessed by ELISA and FCM analysis, respectively. Results Human data: The IHC analysis of human renal specimens revealed that the positive area of CD47 of AAV was greater than that of MGA. In particular, the CD47-overexpressed cells were seen in glomeruli with necrotic crescent formation. In vitro: Mean fluorescence intensity (MFI) of CD47 in ANCA-IgGs treated neutrophils (NETs) was significantly higher than that in control IgGs treated neutrophils (ANCA-IgG; 442±21.4 a.u. vs control IgG; 402±10 a.u., p&amp;lt;0.05). In efferocytosis assay, apoptotic neutrophils were engulfed by macrophages (efferocytosis rate/ apoptotic neutrophil; 20.5±3.8%, live neutrophils; 0.9±0.5%). The efferocytosis rate of ANCA-induced NETs significantly decreased compared to apoptotic neutrophil, but anti-CD47 mAb improved the efferocytosis of ANCA-NETs (efferocytosis rate/ anti-CD47 mAb; 19.1±4.2%, control antibody; 7.7±2.2%, p&amp;lt;0.05). In vivo: the renal histopathological severity score, serum creatinine level of AAV mice treated with anti-CD47 mAb decreased compared to that of AAV mice treated with a control antibody (anti-CD47 mAb; 0.96±0.30 vs control antibody; 0.61±0.32 mg/dL). Although there was no significant difference in the number of splenic cells between anti-CD47 and control antibody treated mice, CD47 blockade therapy significantly reduced serum MPO-ANCA titre (28.5±10.4 vs 45.2±14.5 μg/mL) and renal mRNA expression (IFNα, IFNγ, MCP-1 and perforin) of AAV mice. Conclusion ANCA-mediated NETs might escape from efferocytosis through up-regulation of CD47 and provoke necrotizing vasculitis. CD47 blockade could be a potential novel therapeutic strategy for AAV.

Clinical and histological features in pediatric and adolescent/young adult patients with renal disease: a cross-sectional analysis of the Japan Renal Biopsy Registry (J-RBR).

Only a few studies have investigated epidemiological and clinicopathological information regarding pediatric and adolescent and young adult (AYA) patients with renal disease. The purpose of this study was to clarify the differences and relationship of clinicopathological findings between pediatric and AYA patients using the Japan Renal Biopsy Registry (J-RBR). This cross-sectional study analyzed data from patients registered in the J-RBR between 2007 and 2017. Clinicopathological findings at diagnosis were analyzed for 3,463 pediatric (age < 15years) and 6,532 AYA (age 15-30years) patients. Although chronic nephritic syndrome was the most common clinical diagnosis at age > 5years, nephrotic syndrome was the most frequent diagnosis at age < 4years. The most common pathological diagnosis as classified by pathogenesis in pediatric patients was primary glomerular disease (except IgA nephropathy), whereas IgA nephropathy was increased in AYA patients. Mesangial proliferative glomerulonephritis was the most common pathological diagnosis as classified by histopathology in both pediatric and AYA patients. Minor glomerular abnormalities were the most frequent histopathologic diagnoses of nephrotic syndrome in childhood, but their frequency decreased with age. To the best of our knowledge, this is the first report of clinicopathological features of pediatric and AYA patients in a large nationwide registry of renal biopsy. There were differences of clinical, pathological and histopathologic findings between pediatric and AYA patients.

Persistent Isolated Hematuria in a Japanese Woman.

A 43-year-old Japanese woman, with a family history of hematuria, underwent a kidney biopsy because of persistent hematuria without proteinuria, with serum creatinine of 0.55 mg/dl. Light microscopy revealed minor glomerular abnormalities. Electron microscopy predominantly showed thinning of the glomerular basement membrane (GBM); thickening and lamination were observed in small portions of the GBM (Figure 1A). Atypical Alport syndrome (AS) was suspected. Type IV collagen staining revealed weak α5(IV) expression with enhanced expression of α2(IV) in segmental lesions, consistent with AS (Figure 1, B and C). This case was presumed to be autosomal dominant AS (ADAS), because of the family history and preserved α5(IV) expression in the Bowman’s capsule, which indicate the mutation of COL4A3 or COL4A4 (Figure 1C) (1). Diagnosis of typical AS, namely, X-linked AS in males and autosomal recessive AS, is straightforward, and often made in childhood. In contrast, ADAS is usually suspected in adults because …

A case of minimal change disease after the administration of anti receptor activator of nuclear factor kappa B ligand (RANKL) monoclonal antibody: a case report

BackgroundMinimal change disease (MCD) is one of the causes of idiopathic nephrotic syndrome in adults. The pathogenesis of proteinuria in MCD has not been fully understood. Recently, it has been reported that the receptor activator of nuclear factor-kappa B (RANK)/RANK ligand (RANKL) may contribute to the podocyte biology in kidney diseases. Denosumab is a human anti-RANKL monoclonal antibody used to treat osteoporosis. Here we report a case of MCD after denosumab administration.Case presentationA 59-year-old male without any episodes of proteinuria was given denosumab to treat osteoporosis. Two weeks after its administration, he noticed a foamy urine and bilateral pretibial edema. Laboratory tests revealed that he had severe proteinuria (15g/g Cr), hypoproteinemia (4.0g/dL), and hypoalbuminemia (1.5g/dL). Based on the results, he was diagnosed with nephrotic syndrome. The proteinuria selectivity index was 0.05, indicating selective proteinuria. Renal biopsy showed minor glomerular abnormality with less tubulointerstitial damage, and electron microscopy showed extensive foot process effacement, indicating MCD. With all these results, glucocorticoid therapy of 50mg/day prednisolone was started. After 4weeks of treatment, the urinary protein level remains high (3.1g/g Cr). Prednisolone therapy was continued, and the levels of proteinuria decreased gradually to the range of partial remission (1.2g/g Cr) with another 7weeks of prednisolone treatment, but complete remission was not achieved.ConclusionsThis might be a case wherein RANKL inhibition is associated with the pathogenesis of MCD. Further studies will be needed to elucidate the causal relationship of RANK-RANKL signaling to the pathogenesis of MCD.

Concurrent minimal change nephrotic syndrome and type 1 diabetes mellitus in an adult Japanese woman: a case report

BackgroundConcurrent type 1 diabetes mellitus (T1DM) and idiopathic nephrotic syndrome is rare, and most previously reported cases were in children. We report the case of an adult woman who developed T1DM and minimal change nephrotic syndrome (MCNS) nearly simultaneously.Case presentationA 24-year-old woman had first presented to another hospital with nausea, vomiting, and fatigue. She was diagnosed with diabetic ketoacidosis and T1DM on the basis of her hyperglycemia, ketoacidosis, and positive anti-glutamic acid decarboxylase antibody test result. Rapid infusion of normal saline and insulin administration alleviated hyperglycemia and ketoacidosis. Two weeks after admission, however, she developed nephrotic syndrome (NS) with rapidly decreasing urine volume. She was referred to our hospital with a diagnosis of acute kidney injury. Although she temporarily required dialysis and high doses of insulin, within 1 month NS and acute kidney injury had been alleviated by oral prednisolone and low-density lipoprotein apheresis. Renal biopsy showed minor glomerular abnormalities without diabetic nephropathy, so we diagnosed her with MCNS. Seven weeks after the discharge, NS relapsed, and cyclosporine was added to prednisolone. However, NS relapsed twice within the next 4 months, so we started her on rituximab. At 6 months after initiating rituximab therapy, she remained in complete remission.Her mother also had T1DM but not MCNS. The patient had HLA-DRB1*09:01/09:01, DQB1*03:03/03:03, and her mother had HLA-DRB1*04:05/09:01, DQB1*03:03/04:01.ConclusionsConcurrent T1DM and MCNS is rare and their coexistence might be coincidental. Alternatively, they might have been caused by an underlying, unidentified genetic predisposition. Previous reports and our patient’s findings suggest that specific HLA alleles and haplotypes or a Th1/Th2 imbalance might be associated with T1DM and MCNS that occurred nearly simultaneously.

Risk Factors of Acute Kidney Injury Complicating Adult Primary Nephrotic Syndrome

Objective To explore the risk factors of acute kidney injury(AKI)in adult primary nephrotic syndrome(PNS). Methods Totally 185 patients with PNS were divided into AKI group(n=51)and non-AKI group(n=134).The demographic data and clinical and histological features at admission were compared between the two groups.The independent risk factors for AKI were evaluated by Logistics regression analysis. Results In 51 PNS patients with AKI,the common pathological types of AKI included minor glomerular abnormalities(29.4%),IgA nephropathy(25.5%),and membranous nephropathy(17.6%).The incidences of renal tubular casts and epithelial vacuoles in the AKI group were significantly higher than those in the non-AKI group(P=0.004,P=0.030).Males were more likely to suffer from AKI than females(P=0.000).Patients in AKI group had significantly lower albumin level(P=0.015)and higher levels of random urine protein,serum creatinine,uric acid,urea nitrogen,and triglyceride than non-AKI group(P=0.030,P=0.000,P=0.000,P=0.000,and P=0.006),and polyserous and oliguria occurred more often in the AKI group(P=0.000,P=0.002).The AKI group had significantly higher incidences of high blood pressure and infections(P=0.035,P=0.000).Multivariate logistics regression analysis showed albumin(<25 g/L),serum creatinine(>96 μmol/L),urea nitrogen(≥6.8 mmol/L),uric acid(≥400 μmol/L),diabetes,infection,and renal tubular casts were the independent risk factors for AKI. Conclusions AKI complicating PNS is associated with a variety of factors.Its independent risk factors include the levles of albumin,serum creatinine,urea nitrogen,and uric acid,diabetes,infections,and renal tubular casts.

Two cases of idiopathic steroid-resistant nephrotic syndrome complicated with thrombotic microangiopathy

BackgroundThrombotic microangiopathy (TMA) is a histopathological entity associated with microangiopathic hemolytic anemia, thrombocytopenia, and end-organ ischemic damage. Although TMA is caused by various diseases, there have been few reports regarding children with idiopathic nephrotic syndrome (NS) and TMA. Here we report two 1-year-old infants with steroid-resistant NS (SRNS) who presented with severe hypertension, acute kidney injury (AKI), and TMA.Case presentationThe diagnosis of NS was complicated with anemia, AKI, and hypertension. Maximum blood pressure was 150/70 mmHg in Case 1 and 136/86 mmHg in Case 2. There was no thrombocytopenia during their clinical course in both cases. Renal biopsy showed the features of TMA, including endothelial cell swelling, capillarectasia or marked mesangiolysis, along with mesangial proliferation in Case 1 and TMA with minor glomerular abnormalities in Case 2. Hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, and secondary TMA other than that caused by hypertension were excluded. Oral prednisolone therapy, frequent infusion of albumin and diuretics, and multiple anti-hypertensive drugs were initiated. Blood pressure was controlled after 6 and 7 days from initiation of multiple anti-hypertensive drugs and lisinopril was added due to persistent mild proteinuria and mild hypertension after improvement of renal function in both cases. Proteinuria resolved completely 4 months after admission with daily oral prednisolone for 4 weeks followed by alternative daily oral prednisolone for 4 weeks in Case 1. Proteinuria resolved completely 10 months after admission with initial prednisolone treatment for 4 weeks followed by cyclosporine A and intravenous methylprednisolone pulse therapy in Case 2. The follow-up biopsy showed no TMA findings in both patients. Because the patient in Case 1 subsequently developed frequent relapsing NS, cyclosporine A was commenced after the second biopsy and he did not have any flares for 2 years. Renal function was normal in Case 1 and mildly decreased in Case 2 at last follow-up (creatinine-eGFR of 136.2 mL/min/cm2 in Case 1 and 79.5 mL/min/cm2 in Case 2).ConclusionSevere hypertension and AKI can be signs of TMA in patients with SRNS. Strict anti-hypertensive therapy might improve renal outcomes.

SAT-415 SEVERE GLOMERULAR ENDOTHELIAL INJURY AND MILD TO MODERATE PROTEINURIA DUE TO TAFRO SYNDROME WITH RENAL DYSFUNCTION

TAFRO syndrome has been recognized as a severe subtype of idiopathic multicentric Castleman’ s disease(iMCD), and renal dysfunction is a life threatening complication of this disease. We previously reported two case-reports about renal biopsies of TAFRO syndrome, showing endocapillary proliferative glomerulonephritis, but precise mechanism and clinical course have not been elucidated yet. To further evaluate the characteristics of renal dysfunction due to TAFRO syndrome, we conducted a cross-sectional study. The object of patients were either diagnosed as iMCD or TAFRO syndrome who were extracted from 4,248 renal biopsies performed between 2001 and 2018. The renal biopsies were evaluated by light microscopy, immunofluorescence staining, and electron microscopy. Clinical and laboratory data were collected from electrical medical chart. Statistical analysis was conducted by using R version 3.6.1. This observational study was approved by IRB and informed consent was obtained from all living patients. Fifteen cases were eligible for the study, and seven were diagnosed as TAFRO syndrome while eight were as iMCD without TAFRO syndrome (iMCD-NOS). Patients with TAFRO were lower platelet count (36 [28-115]*103/μL in TAFRO syndrome vs 308 [130-424*103/μL] in iMCD-NOS, p-value <0.01), higher serum ALP (641 [534-1438] IU/L vs199 [85-352]IU/L, p<0.01), total protein(5.2 [5.0-6.8] g/dL vs 10.5 [7.7-14.8]g/dL, p<0.01), and lower IgG level(835 [684-1449]mg/dL vs 5249 [2800-8198]mg/dL). Proteinuria in TAFRO syndrome was mild to moderate level and lower than iMCD-NOS, but this was not statistically significant (0.45[0.28-3.71]g/gCre vs 1.07[0.04-5.34]g/gCre, p=0.43). There was no statistical difference in serum creatinine level, serum albumin level and hematuria. In renal biopsy, severe endothelial injury such as endothelial swelling and narrowing of glomerular tuft was commonly observed in TAFRO syndrome (figure), while varieties of histological diagnosis were found in iMCD-NOS; AA amyloidosis (2 cases), membranous nephritis(2 cases), minor glomerular abnormality (2 cases), nephrosclerosis(1 case), IgA deposition(1case), renal sclerosis (1 case). In addition, any deposition was not detected by electron dense deposit or immunofluorescence staining in TAFRO syndrome. Hemodialysis was required for 4 out of 7 patients with TAFRO syndrome and all of them recovered after the initiation of anti IL-6 receptor antibody or anti CD20 monoclonal antibody. On the other hand, 3 out of 8 patients with iMCD-NOS required maintenance hemodialysis despite of anti IL-6 receptor antibody based immunosuppressive therapy.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Mild to moderate proteinuria, severe endothelial injury without any deposit were common characteristic of TAFRO syndrome compared with iMCD-NOS. Cytokine targeted immunosuppressive therapy was effective in severe renal dysfunction due to TAFRO syndrome even if hemodialysis was required. The difference in treatment response between TAFRO syndrome and iMCD-NOS might be related to the pathogenesis of glomerular changes of both diseases.

Minor Glomerular Abnormalities are Associated with Deterioration of Long-Term Kidney Function and Mitochondrial Injury.

Minor glomerular abnormalities (MGAs) are unclassified glomerular lesions indicated by the presence of minor structural abnormalities that are insufficient for a specific pathological diagnosis. The long-term clinical outcomes and pathogenesis have not been examined. We hypothesized that MGAs would be associated with the deterioration of long-term kidney function and increased urinary mitochondrial DNA (mtDNA) copy numbers. We retrospectively enrolled patients with MGAs, age-/sex-/estimated glomerular filtration rate (eGFR)-matched patients with immunoglobulin A nephropathy (IgAN), and similarly matched healthy controls (MHCs; n = 49 each). We analyzed the time × group interaction effects of the eGFR and compared mean annual eGFR decline rates between the groups. We prospectively enrolled patients with MGAs, age- and sex-matched patients with IgAN, and MHCs (n = 15 each) and compared their urinary mtDNA copy numbers. Compared to the MHC group, the MGA and IgAN groups displayed differences in the time × group effects of eGFR, higher mean annual rates of eGFR decline, and higher urinary mtDNA copy numbers; however, these groups did not significantly differ from each other. The results indicate that MGAs are associated with deteriorating long-term kidney function, and mitochondrial injury, despite few additional pathological changes. We suggest that clinicians conduct close long-term follow-up of patients with MGAs.