[Clinical features and TTC21B genotype of a child with nephronophthisis type 12].

Nephronophthisis (NPHP) is a group of autosomal recessive tubulointerstitial cystic kidney disorders. This article reports a case of NPHP type 12 caused by TTC21B mutations. The girl had an insidious onset, with moderate proteinuria, renal dysfunction, stage 2 hypertension, situs inversus, and short phalanges when she visited the hospital for the first time at the age of 3 years and 6 months. The renal lesions progressed to end-stage renal disease (ESRD) before she was 4 years old. Urine protein electrophoresis showed glomerular proteinuria. There were significant increases in urinary ß2-microglobulin and α1-microglobulin. Gene detection revealed two compound heterozygous mutations, c.1552T>C (p.C518R) and c.752T>G (p.M251R), in the TTC21B gene, which came from her father and mother respectively. The c.752T>G mutation was a novel mutation. It is concluded that besides typical tubular changes of NPHP, marked glomerular damage is also observed in patients with TTC21B gene mutations.

Overproduction of Mitochondrial Fission Proteins in Membranous Nephropathy in Children.

BACKGROUND/AIMS: The molecules involved in nephrotic syndrome (NS) have not been fully clarified. Mitochondrial fission proteins are found to be involved in podocyte injury in vitro. Increased glomerular expression of mitochondrial fission proteins was found in adriamycin nephropathy in our previous study. Whether or not mitochondrial fission proteins are involved in podocyte injury in NS is not clear. This study explored the glomerular expression and possible pathological significance of mitochondrial fission-associated proteins, including dynamin-related protein 1 (Drp1) and mitochondrial fission protein 1 (Fis1), in children with NS. METHODS: Eighteen children with primary NS, including 6 with minimal change disease, 6 with focal segmental glomerulosclerosis, 6 with membranous nephropathy, 6 children with isolated haematuria and 3 normal controls were included. The glomerular expression of Drp1, phospho-Drp1 (Ser616) and Fis1, urinary protein measurements, and podocyte mitochondrial density under electron microscopy were investigated and compared. RESULTS: Glomerular expression of Drp1, phospho-Drp1 (Ser616) and Fis1 was mainly increased in children with NS with membranous nephropathy. No relationship was found between glomerular expression of Drp1, phospho-Drp1 (Ser616) and Fis1 and podocyte mitochondrial density or urinary protein measurements. CONCLUSION: Glomerular overproduction of Drp1, phospho-Drp1 (Ser 616) and Fis1 occurred mainly in children with membranous nephropathy. The pathological significance deserves further investigation.

IP3R-Grp75-VDAC1-MCU calcium regulation axis antagonists protect podocytes from apoptosis and decrease proteinuria in an Adriamycin nephropathy rat model.

BACKGROUND: The mechanism of podocyte apoptosis is not fully understood. In addition, the role of the inositol 1,4,5-triphosphate receptor (IP3R)/glucose-regulated protein 75 (Grp75)/voltage-dependent anion channel 1 (VDAC1)/mitochondrial calcium uniporter (MCU) calcium regulation axis, which is located at sites of endoplasmic reticulum (ER) mitochondria coupling, in the mechanism of podocyte apoptosis is unclear. This study aimed to understand the roles of this axis in podocyte apoptosis and explore potential targets for podocyte protection. METHODS: The expression of IP3R, Grp75, VDAC1, and MCU and mitochondrial Ca2+ were analyzed during Adriamycin- or angiotensin II-induced apoptosis in cultured mouse podocytes. The interaction between IP3R, Grp75, and VDAC1 was investigated using co-immunoprecipitation experiments. The effects of IP3R, Grp75, and MCU agonists and antagonists on mitochondrial Ca2+ and apoptosis were investigated in cultured podocytes. The podocyte-protective effects of an MCU inhibitor were further investigated in rats with Adriamycin-induced nephropathy. RESULTS: Increased expression of IP3R, Grp75, VDAC1 and MCU, enhanced interaction among the IP3R-Grp75-VDAC1 complex, mitochondrial Ca2+ overload, and increased active caspase-3 levels were confirmed during Adriamycin- or angiotensin II-induced mouse podocyte apoptosis. Agonists of this axis facilitated mitochondrial Ca2+ overload and podocyte apoptosis, whereas specific antagonists against IP3R, Grp75, or MCU prevented mitochondrial Ca2+ overload and podocyte apoptosis. A specific MCU inhibitor prevented Adriamycin-induced proteinuria and podocyte foot process effacement in rats. CONCLUSIONS: This study identified a novel pathway in which the IP3R-Grp75-VDAC1-MCU calcium regulation axis mediated podocyte apoptosis by facilitating mitochondrial Ca2+ overload. Antagonists that inhibit Ca2+ transfer from ER to mitochondria protected mouse podocytes from apoptosis. An MCU inhibitor protected podocytes and decreased proteinuria in rats with Adriamycin-induced nephropathy. Therefore, antagonists to this pathway have promise as novel podocyte-protective drugs.

Characterization of microbiota in systemic-onset juvenile idiopathic arthritis with different disease severities.

BACKGROUND: Systemic-onset juvenile idiopathic arthritis (SoJIA) is one of most serious subtypes of juvenile idiopathic arthritis. Although the pathogenesis of SoJIA remains unclear, several studies have suggested a correlation between gut dysbiosis and JIA. Further understanding of the intestinal microbiome may help to establish alternative ways to treat, or even prevent, the disease. AIM: To explore alterations in fecal microbiota profiles in SoJIA patients and to evaluate the correlations between microbiota and clinical parameters. METHODS: We conducted an observational single-center study at the Pediatric Department of Peking Union Medical College Hospital. Children who were diagnosed with SoJIA at our institution and followed for a minimum period of six months after diagnosis were recruited for the study. Healthy children were recruited as a control group (HS group) during the same period. Clinical data and stool samples were collected from SoJIA patients when they visited the hospital. RESULTS: The SoJIA group included 17 active and 15 inactive consecutively recruited children; the control group consisted of 32 children. Firmicutes and Bacteroidetes were the two most abundant phyla among the total sample of SoJIA children and controls. There was a significant difference among the three groups in observed species, which was the highest in the Active-SoJIA group, followed by the Inactive-SoJIA group and then HS group (Active-SoJIA vs HS: P = 0.000; and Inactive-SoJIA vs HS: P = 0.005). We observed a lower Firmicutes/Bacteroidetes ratio in SoJIA patients (3.28 ± 4.47 in Active-SoJIA, 5.36 ± 8.39 in Inactive-SoJIA, and 5.67 ± 3.92 in HS). We also observed decreased abundances of Ruminococcaceae (14.9% in Active-SoJIA, 17.3% in Inactive-SoJIA, and 22.8% in HS; Active-SoJIA vs HS: P = 0.005) and Faecalibacterium (5.1% in Active-SoJIA, 9.9% in Inactive-SoJIA, and 13.0% in HS; Active-SoJIA vs HS: P = 0.000) in SoJIA compared with HS. By contrast, the abundance of Bacteroidaceae was the highest in the Active-SoJIA group, followed by the Inactive-SoJIA and HS groups (16.5% in Active-SoJIA, 12.8% in Inactive-SoJIA, and 9.7% in HS; Active-SoJIA vs HS: P = 0.03). The Spearman correlation analysis revealed a negative correlation between Proteobacteria or Enterobacteriaceae and juvenile arthritis disease activity score on 27 joints (JADAS-27). CONCLUSION: The composition of the intestinal microbiota is different in SoJIA patients compared with healthy children. The dysbiosis presents partial restoration in inactive status patients.