• Childhood Kidney Diseases
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• v.23 no.2
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• pp.86-92
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• 2019

Steroid-resistant nephrotic syndrome (SRNS) has long been a challenge for clinicians due to its poor responsiveness to immunosuppressants, and rapid progression to end-stage renal disease. Identifying a monogenic cause for SRNS may lead to a better understanding of podocyte structure and function in the glomerular filtration barrier. This review focuses on genes associated with slit diaphragm, actin cytoskeleton, transcription factors, nucleus, glomerular basement membrane, mitochondria, and other proteins that affect podocyte biology.

• Childhood Kidney Diseases
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• v.19 no.2
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• pp.65-70
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• 2015

It is well known that proteins present in the primary urine are reabsorbed in the renal proximal tubules, and that this reabsorption is mediated via the megalin-cubilin complex and the neonatal $Fc{\gamma}$ receptor. However, the reabsorption is also thought to be influenced by an electrostatic interaction between protein molecules and the microvilli of the renal proximal tubules. By analyzing the charge diversity of urinary IgG, we showed that this reabsorption process occurs in a cationic charge-preferential manner. The charge-selective molecular sieving function of the glomerular capillary walls has long been a target of research since Brenner et al. demonstrated the existence of this function by a differential clearance study by using the anionic dextran sulfate polymer. However, conclusive evidence was not obtained when the study was performed using differential clearance of serum proteins. We noted that immunoglobulin (Ig) A and IgG have similar molecular sizes but distinct molecular isoelectric points. Therefore, we studied the differential clearance of these serum proteins (clearance IgA/clearance IgG) in podocyte diseases and glomerulonephritis. In addition, we studied this differential clearance in patients with Dent disease rather than in normal subjects because the glomerular sieving function is considered to be normal in subjects with Dent disease. Our results clearly showed that the charge-selective barrier is operational in Dent disease, impaired in podocyte disease, and lacking in glomerulonephritis.

• Childhood Kidney Diseases
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• v.23 no.1
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• pp.1-6
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• 2019

Nephrotic syndrome (NS) is the most common glomerular disorder in childhood, and a vast majority of cases are idiopathic. The precise cause of this common childhood disease is not fully elucidated despite significant advancements in our understanding of podocyte biology. Idiopathic NS has been considered "a disorder of T-cell function" mediated by a circulating factor that alters podocyte function resulting in massive proteinuria since the last four decades. Several circulatory factors released from T-cells are considered to be involved in pathophysiology of NS; however, a single presumptive factor has not been defined yet. Extended evidence obtained by advances in the pathobiology of podocytes has implicated podocytes as critical regulator of glomerular protein filtration and podocytopathy. The candidate molecules as pathological mediators of steroid-dependent NS are CD80 (also known as B7-1), hemopexin, and angiopoietin-like 4. The "two-hit" hypothesis proposes that the expression of CD80 on podocytes and ineffective inhibition of podocyte CD80 due to regulatory T-cell dysfunction or impaired autoregulation by podocytes results in NS. Recent studies suggest that not only T cells but also other immune cells and podocytes are involved in the pathogenesis of MCNS.

• Childhood Kidney Diseases
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• v.17 no.1
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• pp.13-18
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• 2013

Podocytopathy is glomerular lesions characterized by podocyte injury. It is observed in various glomerular diseases, but minimal change disease and focal segmental glomerulosclerosis (FSGS) are the prototypes. In this review, morphologic features of podocyte injury and subtypes of FSGS will be reviewed briefly. Effacement of podocyte foot processes is the most common feature of podocyte injury. As podocytic injury progresses, intracytoplasmic vacuoles, subpodocytic cyst, detachment of podocytes from the glomerular basement membrane and apoptosis develop. Glomerular capillary loops in epithelium-denuded area undergo capillary collapse. Synechia and hyalinosis may accompany this lesion. To manifest segmental sclerosis, podocyte loss above a threshold level may be required. Injured podocytes can injure neighboring intact podocytes, and thereby spread injury within the same lobule. FSGS can be categorized into five subtypes by morphologic characteristics; not otherwise specified (NOS), perihilar, cellular, tip, and collapsing types. Each subtype has been reported to show different clinical courses and associated conditions, but there are controversies on its significance. With recent progress in the discovery of genetic abnormalities causing FSGS and plasma permeability factors, we expect to unravel pathophysiology of FSGS and to understand histological sequences leading to FSGS in near future.

• Journal of Ginseng Research
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• v.47 no.3
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• pp.400-407
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• 2023

Background: Rb3 is a ginsenoside with anti-inflammatory properties in many cell types and has been reported to attenuate inflammation-related metabolic diseases such as insulin resistance, nonalcoholic fatty liver disease, and cardiovascular disease. However, the effect of Rb3 on podocyte apoptosis under hyperlipidemic conditions, which contributes to the development of obesity-mediated renal disease, remains unclear. In the current study, we aimed to investigate the effect of Rb3 on podocyte apoptosis in the presence of palmitate and explore its underlying molecular mechanisms. Methods: Human podocytes (CIHP-1 cells) were exposed to Rb3 in the presence of palmitate as a model of hyperlipidemia. Cell viability was assessed by MTT assay. The effects of Rb3 on the expression of various proteins were analyzed by Western blotting. Apoptosis levels were determined by MTT assay, caspase 3 activity assay, and cleaved caspase 3 expression. Results: We found that Rb3 treatment alleviated the impairment of cell viability and increased caspase 3 activity as well as inflammatory markers in palmitate-treated podocytes. Treatment with Rb3 dosedependently increased PPARδ and SIRT6 expression. Knockdown of PPARδ or SIRT6 reduced the effects of Rb3 on apoptosis as well as inflammation and oxidative stress in cultured podocytes. Conclusions: The current results suggest that Rb3 alleviates inflammation and oxidative stress via PPARδ-or SIRT6-mediated signaling, thereby attenuating apoptosis in podocytes in the presence of palmitate. The present study provides Rb3 as an effective strategy for treating obesity-mediated renal injury.

• Journal of Trauma and Injury
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• v.32 no.2
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• pp.111-114
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• 2019

Minimal change disease (MCD) in children has a favorable long-term prognosis, and development of end-stage renal disease is very uncommon; less than 5%. In the first case of its kind, we report a 21-year-old female with a history of MCD at the age of 6, who had late relapse subsequent to a motorcycle accident resulting in a de-gloving skin injury and intensive care unit admission. MCD was confirmed by normal light microscopy, podocyte effacement on electron microscopy and absence of any deposits on immunofluorescence 3 weeks after the incident due to critical illness. It is postulated that the skin injury is what caused the relapse of MCD.

• Childhood Kidney Diseases
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• v.16 no.1
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• pp.21-31
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• 2012

Focal segmental glomerulosclerosis (FSGS) is the name of the primary glomerular disease as well as the terminology to describe the secondary phenomena of any other glomerular diseases. It is characterized by sclerosis, hyalinosis, foam cell infiltration, vacuolar change of podocytes, and halo formation in the glomerulus. Throughout the interstitium, lymphocytes infiltration, tubular atrophy and vascular changes are accompanied. Occasionally, IgM and/or C3 depositions are noted in the sclerotic areas. Electron microscopically, diffuse effacement of foot processes are seen in non-sclerotic area like minimal change disease. Podocyte injury patterns including vacuolar changes are frequently examined. Recently, Columbia group has suggested morphologic classification of FSGS and they demonstrated very good prognosis of tip lesion and poor prognosis of both collapsing and cellular types. However, the pathogenetic classification has been suggested by others; hyperfilteration, podocyte injury, genetic lesions etc. Further studies are necessary to understand and treat this disease.

• Childhood Kidney Diseases
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• v.14 no.1
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• pp.51-61
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• 2010

Purpose : Previous studies have suggested that Chemokine (C-C motif) ligand-2 (CCL-2; also known as MCP-1) and CCL-5 (also known as RANTES) are possibly associated with the pathogenesis of various inflammatory and non-inflammatory renal diseases. The present study was conducted to investigate association of polymorphisms of CCL-2 and CCL-5 genes with childhood IgA nephropathy (IgAN). Methods : The authors analyzed six single nucleotide polymorphisms (SNPs) of CCL-2 and CCL-5 in 196 pediatric IgAN patients and in 285 healthy controls. We compared variations in SNPs between two several sets of IgAN subgroups, allocated by presence of proteinuria (>4 mg/$m^2$/hour), podocyte foot process effacement, and pathologically advanced disease markers, such as interstitial fibrosis, tubular atrophy, or global sclerosis. Results : Genotypic data of IgAN patients and controls showed no significant SNP frequency difference in both of of CCL-2 and CCL-5. Even though two linkage disequilibrium blocks were formed, there was no significance in the haplotype analysis. In the patient subgroup analysis, no SNP of CCL-2 and CCL-5 was found to be associated with the presence of proteinuria, podocyte foot process effacement, and pathologically advanced disease markers. Conclusion : Our data indicate that no association exists between CCL-2 and CCL-5 SNPs and childhood IgAN susceptibility, and presence of proteinuria, podocyte foot process effacement, and pathologic progression of IgAN.

• Childhood Kidney Diseases
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• v.15 no.2
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• pp.138-145
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• 2011

Purpose : To test whether the expression of ${\beta}$-catenin, a component of podocyte as a filtration molecule, would be altered by puromycin aminonucleoside (PAN) in the cultured podocyte in vitro. Methods : We cultured rat glomerular epithelial cells (GEpC) with various concentrations of PAN and examined the distribution of ${\beta}$-catenin by confocal microscope and measured the change of ${\beta}$-catenin expression by Western blotting and reverse transcriptase-polymerase chain reaction (RT-PCR). Results :We found that ${\beta}$-catenin relocalized from peripheral cytoplasm to inner cytoplasm, therefore, intercellular separations were seen in confluently cultured cells by high concentrations of PAN in immunofluorescence views. In Western blotting of GEpC, PAN ($50{\mu}g/mL$) decreased ${\beta}$-catenin expression by 34.9% at 24 hrs and 34.3% at 48 hrs, compared to those in without PAN condition (P<0.05). In RT-PCR, high concentrations ($50{\mu}g/mL$) of PAN also decreased ${\beta}$-catenin mRNA expression similar to protein suppression by 25.4% at 24 hrs and 51.8% at 48 hrs (P<0.05). Conclusion : Exposure of podocytes to PAN in vitro relocates ${\beta}$-catenin internally and reduces ${\beta}$-catenin mRNA and protein expression, which could explain the development of proteinuria in experimental PAN-induced nephropathy.

• Childhood Kidney Diseases
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• v.21 no.2
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• pp.152-155
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• 2017

Orthostatic or postural proteinuria is the most common cause of asymptomatic proteinuria in children. As orthostatic proteinuria (OP) is a benign disease with relatively good prognosis, it has no specific management, and patients only need to be observed. However, if OP shows a persistently high level of proteinuria, in theory, glomerular changes can occur. An 11-year-old girl was referred to the hospital due to asymptomatic proteinuria and was diagnosed as having OP based on the results of clinical and laboratory examinations, urinalysis, and protein/creatinine (TP/Cr) ratio at both supine and erect positions. During follow-up observation, the 24-hour TP/Cr ratio was persistently higher than 1.5 mg/mg for 2 years. We performed renal biopsy, which showed mesangial proliferative glomerular lesions with focal effacement of the podocyte foot processes, but without immune depositions. OP can be accompanied by glomerular lesions if moderate to severe proteinuria persists.