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To understand the genetics of steroid-sensitive nephrotic syndrome (SSNS), we conducted a genome-wide association study in 987 childhood SSNS patients and 3,206 healthy controls with Japanese ancestry. Beyond known associations in the HLA-DR/DQ region, common variants in NPHS1-KIRREL2 (rs56117924, P[4.94E-20, odds ratio (OR) [1.90)

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Our protocol was useful and safe for refractory NS. However, RTX administration four times might have been excessive in patients who had no relapse by 1 year after the initial RTX administration. Further investigation of the most appropriate method of RTX administration is required.

Common pathogens of clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) are viruses, such as influenza virus. However, bacteria are rare pathogens for MERS. We report the first patient with MERS associated with febrile urinary tract infection. A 16-year-old lupus patient was admitted to our hospital. She had fever, headache, vomiting, and right back pain. Urinary analysis showed leukocyturia, and urinary culture identified Klebsiella pneumoniae. Cerebrospinal fluid examination and brain single-photon emission computed tomography showed no abnormalities. Therefore, she was diagnosed with febrile urinary tract infection. For further examinations, 99mTc-dimercaptosuccinic acid renal scintigraphy showed right cortical defects, and a voiding cystourethrogram demonstrated right vesicoureteral reflux (grade II). Therefore, she was diagnosed with right pyelonephritis. Although treatment with antibiotics administered intravenously improved the fever, laboratory findings, and right back pain, she had prolonged headaches, nausea, and vomiting. T2-weighted, diffusion-weighted, and fluid attenuated inversion recovery images in brain magnetic resonance imaging showed high intensity lesions in the splenium of the corpus callosum, which completely disappeared 1 week later. These results were compatible with MERS. To the best of our knowledge, our patient is the first patient who showed clinical features of MERS associated with febrile urinary tract infection. Conclusion: In patients with pyelonephritis and an atypical clinical course, such as prolonged headache, nausea, vomiting, and neurological disorders, the possibility of MERS should be considered.

Background Immunoglobulin A nephropathy (IgAN) is a major cause of end‐stage renal disease. Complement activation via the lectin pathway influences outcomes in IgAN. We examined the association of glomerular C4d deposition with clinicopathological severity at diagnosis and the disappearance of proteinuria in Japanese pediatric IgAN patients. Methods We retrospectively analyzed 25 children newly diagnosed with IgAN at Hokkaido University Hospital. We evaluated glomerular C4d immunofluorescent staining at diagnosis. We compared clinical findings, pathological findings (based on Oxford classification), and the disappearance of proteinuria within 24 months after renal biopsy between C4d‐positive and C4d‐negative patients. Results Glomerular C4d staining was observed in 14 patients (56.0%). C4d‐positive patients had significantly higher proteinuria at diagnosis than C4d‐negative patients (2.03 g/gCr vs 0.78 g/gCr; P = 0.005). The number of glomeruli with segmental glomerulosclerosis or adhesion (8.0% vs 0.0%; P = 0.046) and the extent of tubular atrophy/interstitial fibrosis (9.46% vs 2.86%; P = 0.031) were significantly increased in C4d‐positive patients compared with C4d‐negative patients. Further, the proportion of patients with modified T1 (>10%) was significantly higher in the C4d‐positive group than the C4d‐negative group. There was no significant difference, however, in the disappearance rate of proteinuria at 24 months after renal biopsy between groups (64% vs 82%; P = 0.149). Conclusions Glomerular C4d deposition was associated with clinicopathological severity at diagnosis in Japanese pediatric patients with IgAN. Glomerular C4d deposition, however, was not a predictor of the disappearance of proteinuria within 24 months after diagnosis in Japanese pediatric patients with IgAN.

Background/Aims: De novo expression of CD44 is considered as a marker of parietal epithelial cell (PEC) activation. The aim of our study was to explore CD74 expression, which can form a complex with CD44, in PECs during the progression of focal segmental glomerulosclerosis (FSGS). To clarify the role of CD74 expression and of its interaction with CD44, we generated a new mouse model with enhanced PEC activation through lipopolysaccharide (LPS) application to adriamycin (ADR)-induced nephropathy mice (LPS-treated ADR mice). Methods: As a new model, LPS was intraperitoneally injected into the mice 3 weeks after ADR injection. The mice were divided into 3 categories: control mice, ADR mice and LPS-treated ADR mice. Renal function parameters, histologic changes and immunohistochemical expression of CD74 and other PEC activation markers were analyzed after LPS application. Results: After LPS stimulation, the glomeruli were characterized by enlarged epithelial cells with strong CD74 expression, followed by pseudo-crescent formation. By double staining, CD74-positive enlarged cells showed co-expression of classical PEC markers, but not of Lotus tetragonolobus lectin (marker of proximal tubular cells), suggesting amplification of PEC activation. Time-course analysis displayed marked upregulation of CD74 expression during rapid PEC activation compared with CD44. Additionally, the time-dependent change in ERK phosphorylation showed a similar pattern to CD74. Conclusion: Our results indicate that CD74 can be a marker for PEC activation in FSGS. By modifying the ADR mouse model through LPS treatment, we found that CD74 upregulation better reflects a rapid amplification of PEC activation than CD44 expression.

Reduced number of glomeruli associated with prematurity was speculated to have caused compensatory glomerular hyperfiltration, hypertrophy, and hypertension in children born with ELBW when they developed proteinuria. ARB could have been effective for proteinuria by reducing glomerular hypertension. Physicians should be aware of proteinuria in children born with ELBW because there is an increasing number of ELBW survivors as a result of advances in medical technology.