EXPRESS: Clinical Outcomes and Clinico-Pathological Correlations in Children with MPO-ANCA-Associated Glomerulonephritis Showing Renal Arteritis

OBJECTIVE

The aim of this study was to evaluate the clinical features, pathological characteristics and prognosis in myeloperoxidase (MPO)-antineutrophil cytoplasmic antibodies-associated glomerulonephritis (AAGN) with renal arteritis.

METHODS

The study involved 97 children from five pediatric clinical centers with MPO-AAGN who exhibited distinct clinical features. The patients were divided into AAGN-A+ and AAGN-A-, based on the presence or absence of arteritis, and the disparities in clinical, histopathological characteristics, and prognosis between the two groups were evaluated.

RESULT

In contrast to the AAGN-A- group, the children in the AAGN-A+ group exhibited more pronounced clinical symptoms and renal pathological injury. Arteritis positively moderately correlated with the serum creatinine (Scr), IL-6 (interleukin-6), urinary neutrophil gelatinase-associated lipocalin (NGAL), negatively moderately correlated with serum complement C3. The renal survival rate in the AAGN-A+ group was significantly poorer than AAGN-A- group (χ2=4.278, P=0.039). Arteritis showed a good predictive value for end-stage kidney disease (ESKD), and C3 deposition and arteritis were independent risk factors for the development of ESKD in children with MPO-AAGN.

CONCLUSION

Arteritis is a significant pathological change observed in children with MPO-AAGN, and the formation of arteritis may be related to the inflammatory response and activation of the complement system.

Validation of a renal risk score in a cohort of children with ANCA-associated glomerulonephritis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is extremely rare in children. Renal involvement is a common and severe complication of AAV as it can cause end stage kidney disease (ESKD). ANCA renal risk score (ARRS) is helpful in predicting long-term ESKD in patients with ANCA-associated glomerulonephritis (AAGN). This retrospective study included 61 consecutive patients with kidney biopsy specimen-proven AAGN from Clinical Center for Children's Kidney Disease in China. Each patient was assessed by eGFR, normal glomeruli, and tubular atrophy/interstitial fibrosis, and the renal outcome was evaluated using the ARRS. Based on the ARRS, 27 (44.26%), 21 (34.43%), and 13 (21.31%) patients were divided into the low-risk, medium-risk, and high-risk groups, respectively. The median follow-up period was 46.36 (14.58-95.62) months. The high-risk group had worse renal outcomes than the low-risk group (p< 0.05) and the medium-risk group (p < 0.05). COX multivariate regression analysis showed that eGFR ≤ 15 ml/min/1.73 m2 (p = 0.015, Hazard Ratio (HR) = 9.574, 95% CI 4.205-25.187) and ARRS (p = 0.012, HR = 2.115, 95% CI 1.206-4.174) were independent risk factors for ESKD.The area under the curve for ESKD prediction of ARRS was 0.880, and the best cutoff value was 5.50. Delong test result showed that ARRS exhibited better predictive value for ESKD than the Berden classification (p < 0.001) and rapidly progressive glomerulonephritis (p < 0.001). This is the first study to investigate the value of the ARRS for predicting renal prognosis among Chinese children. The ARRS is a preferred index that can predict ESKD in Chinese children with AAGN.

Bowman capsule rupture in children with myeloperoxidase-antineutrophil cytoplasmic antibody-associated glomerulonephritis predicts poor renal survival

Background

Recent developments indicated that Bowman capsule rupture (BCR) is observed in antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (AAGN). We aimed to explore the relationship between BCR and clinical manifestations, pathological changes, and prognosis in children with myeloperoxidase (MPO)-AAGN.

Methods

A total of 56 children with MPO-AAGN were divided into BCR (+) and BCR (-) groups according to the status of Bowman's capsule. Clinical and histological features and renal outcomes were compared, and the predictive value of BCR for end-stage kidney disease (ESKD) of MPO-AAGN was evaluated.

Results

After retrospective analysis of the data, 24 children (42.9%) were found to have BCR. The results showed that BCR positively correlated with intrarenal immune cell infiltrates, obsolescence and crescents in glomeruli, tubulointerstitial inflammation, tubulitis, and tubular atrophy negatively correlated with normal glomeruli and immunoglobulin G deposition in the kidney. The clinical features and kidney pathological changes were more severe in the BCR (+) group than BCR (-) group, and the renal survival rate was significantly poorer in the BCR (+) group than BCR (-) group (χ2 = 5.45, p = 0.02). Moreover, estimated glomerular filtration rate (≤15 mL/min/1.73 m2), BCR and ANCA renal risk score (ARRS) were independent risk factors for the development of ESKD in children with MPO-AAGN. After combining BCR with the Berden classification and ARRS, our data suggested that the Berden classification + BCR and ARRS + BCR showed better predictive values for ESKD than those of the Berden classification and ARRS, respectively.

Conclusion

BCR is an important pathological lesion that correlates with severe clinical manifestations, pathological changes, and poor prognosis in children with MPO-AAGN.

Risk factors for renal outcomes in children with antineutrophil cytoplasmic antibody-associated vasculitis: a nationwide retrospective study in China

BACKGROUND

Pediatric antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is a life-threatening systemic vasculitis featured by liability to renal involvement. However, there are few studies on the risk factors and predictive models for renal outcomes of AAV in children.

METHODS

Data from 179 AAV children in multiple centers between January 2012 and March 2020 were collected retrospectively. The risk factors and predictive model of end-stage renal disease (ESRD) in AAV were explored.

RESULTS

Renal involvement was the most typical manifestation (95.5%), and the crescent was the predominant pathological lesion (84.9%). The estimated glomerular filtration rate (eGFR) was evaluated in 114 patients, of whom 59.6% developed ESRD, and the median time to ESRD was 3.20 months. The eGFR [P = 0.006, odds ratio (OR) = 0.955, 95% confidence interval (CI) = 0.924-0.987] and the percentages of global glomerulosclerosis (pGGS; P = 0.018, OR = 1.060, 95% CI = 1.010-1.112) were independent risk factors for ESRD of renal biopsy. Based on the pGGS and eGFR at renal biopsy, we developed three risk grades of ESRD and one predictive model. The Kaplan‒Meier curve indicated that renal outcomes were significantly different in different risk grades (P < 0.001). Compared with serum creatinine at baseline, the predictive model had higher accuracy (0.86 versus 0.58, P < 0.001) and a lower coefficient of variation (0.07 versus 0.92) in external validation.

CONCLUSIONS

Renal involvement is the most common manifestation of pediatric AAV in China, of which more than half deteriorates into ESRD. The predictive model based on eGFR at renal biopsy and the pGGS may be stable and accurate in speculating the risk of ESRD in AAV children. Supplementary file 2 (MP4 18937 KB).

Clinical significance of kidney immune complex deposition in children with acute interstitial nephritis disease

BACKGROUND

Acute interstitial nephritis (AIN) is a relatively rare cause of acute kidney injury (AKI) in children. Immune complex (IC) deposition was rare in renal pathology of AIN.

METHODS

Based on the status and position of IC deposition, a total of 78 children with AIN were divided into two groups: the non-IC group and IC group. IC group was further divided into two subgroups: intraglomerular (IG)-IC group and extraglomerular (EG)-IC group. To compare the clinical and histological features, renal outcomes between groups.

RESULTS

The IC deposition, IG-IC and EG-IC deposition were observed in 22 (28.21%), 12 (15.38%) and 10 (12.82%) children, respectively. The IC group demonstrated a higher frequency of AKI, higher level of Scr, urine N-acetyl-β-D-glucosidase (NAG) enzyme, retinol-binding protein (RBP), neutrophil gelatinase-associated lipocalin (NGAL), higher frequency of neutrophils, plasma cells and eosinophils infiltrate, higher scores of interstitial inflammation (i), total inflammation (ti) and interstitial edema, lower level of estimated glomerular filtration rate (eGFR) as compared to non-IC group (p < 0.05, p < 0.01). EG-IC deposition positively moderate correlated with levels of RBP, IG-IC deposition positively moderate correlated with plasma cell infiltrate, interstitial inflammation (i), total inflammation (ti) and interstitial edema. Interstitial inflammation, EG-IC deposition and interstitial edema were risk factors for AKD in AIN, and interstitial fibrosis/tubular atrophy (IF/TA) was a risk factor for CKD in children with AIN.

CONCLUSION

IG-IC and EG-IC deposition positively correlated with severe clinical manifestations, glomerular and tubular injuries, and EG-IC deposition was risk factor for the progression of AIN in children.

[Long-term prognosis of primary focal segmental glomerulosclerosis in children]

Objective: To investigate risk factors for the long-term prognosis of primary focal segmental glomerulosclerosis (FSGS) and associated with renal prognosis in children. Methods: A retrospective study was conducted by collecting clinical data including general information, clinical features and renal pathological findings of 124 children with primary FSGS in Department of Pediatrics of Jinling Hospital from January 2003 to December 2019. The cumulative renal survival rate was calculated by Kaplan-Meier survival analysis. The risk factors related to renal prognosis were identified by Cox regression risk model analysis and receiver operating characteristic (ROC) curve. Results: Among 124 children, 94 were males (75.8%) and 30 were females (24.2%). The children were 16 (14, 17) years of age at the time of kidney biopsies. There were 102 cases (82.3%) aged from 13 to 18 years. The period of follow-up was 64.8 (32.1, 86.0) months. There were 49 cases (39.5%) with nonspecific variant, 33 cases (26.6%) with tip variant, 22 cases (17.7%) with collapsing variant, 14 cases (11.3%) with cellular variant and 6 cases (4.8%) with periportal variant. The data of Kaplan-Meier survival analysis showed that cumulative renal survival rates of end-stage kidney disease (ESKD) or ≥50% decline in estimated glomerular filtration rate (eGFR) from baseline at the year of 5, 10 and 15 after renal biopsies were 66.9%, 51.4% and 21.0% respectively. Multivariate Cox regression analysis showed that hypertension, glomerular segmental sclerosis ratio, moderate to severe chronic tubulointerstitial lesions were independent risk factors for progressing to ESKD or ≥50% reduction in eGFR from baseline in pediatric FSGS (HR=5.28, 1.03, 7.81, 95%CI 2.77-10.05, 1.01-1.04, 4.08-14.98, all P<0.01). ROC curve analysis showed glomerular segmental sclerosis ratio (AUC=0.734, P<0.05, optimal cut-off value=25.4%, sensitivity=50.0%, specificity=88.6%), moderate and severe chronic renal tubulointerstitial lesions (AUC=0.724, P<0.05, sensitivity=46.3%, specificity=98.6%) had good efficacy in evaluating renal outcomes of FSGS. Conclusions: The long-term prognosis of FSGS in children is poor. The risk factors of poor prognosis in children with FSGS are hypertension, moderate to severe chronic renal tubulointerstitial lesions and glomerular segmental sclerosis (≥25.4%).

Relationship between Renal Damage and Serum Complement C3 in Children with Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis

BACKGROUND

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) disease is a well-known antibody-induced autoimmune disease. The pathogenesis of AAV has not yet been completely clarified, but may be related to heredity, infection, environmental factors, cellular immunity, etc. In recent years, complement in AAV pathogenesis has become the latest research hotspot, and the decrease of serum complement C3 is associated with poor prognosis of anti-neutrophil cytoplasmic antibody-associated glomerulonephritis. In the current study, we investigated the associations between serum complement C3 and kidney injury in AAV children.

METHODS

Twenty-four children with AAV admitted to our hospital from June 2014 to June 2019 were divided into the low C3 group and the normal C3 group. All the children have undergone renal biopsy. The clinical manifestations, laboratory tests, renal pathology, treatment, and prognosis of the 2 groups were observed. The primary end point was end-stage renal disease (ESRD).

RESULTS

It was shown that kidney injury was more obvious in patients with low C3 than in patients with normal C3 serum. The values of ESR, Scr, and UA before treatment in the low C3 group were higher than those in the normal C3 group (p < 0.01); the values of RBC, Hb, PLT, ALB, LDH, and eGFR in the normal C3 group were higher than those in the low C3 group (p < 0.01). The values of urinary protein and NAG enzyme in the low C3 group were higher than those in the normal C3 group (p < 0.01). The area of glomerular abandonment, sclerosis, segmental sclerosis, crescent, cellular crescent, cellular fibrous crescent, fibrous crescent, segmental loop necrosis, and the number of cases with acute renal tubulointerstitial lesions in the low C3 group were bigger than those in the normal C3 group (p < 0.05 and < 0.01). The number of cases with C3 deposition in the low C3 group was higher than that in the normal C3 group (p < 0.05). The number of patients receiving CRRT and PE in the low C3 group was higher than that in the normal C3 group (p < 0.05 and < 0.01). In this study, 3 children entered the stage of ESRD and 1 died in the low C3 group.

CONCLUSION

The kidney injury of AAV children with low complement C3 is serious, and the prognosis is poor. We should pay attention to the influence of decreased complement C3 on the condition and prognosis of AAV children.

Comparative Functional Analysis in vitro of 2 COL4A5 Splicing Mutations at the Same Site in 2 Unrelated Alport Syndrome Chinese Families

X-linked Alport syndrome (XLAS) is a common hereditary nephropathy caused by COL4A5 gene mutations. To date, many splice site mutations have been described but few have been functionally analyzed to verify the exact splicing effects that contribute to disease pathogenesis. Here, we accidentally discovered 2 COL4A5 gene splicing mutations affecting the same residue (c.2917+1G>A and c.2917+1G>C) in 2 unrelated Chinese families. In vitro minigene assays showed that the 2 mutations produced 3 transcripts in H293T cells: one with a 96-bp deletion in exon 33, one with exon 33 skipping, and one with exon 33-34 skipping. However, fragment analysis results showed that the main splicing effects of the 2 mutations were different, the c.2917+1G>A mutation mainly activated a cryptic donor splice site in exon 33 and resulted in the deletion of 96 bp in exon 33, while the c.2917+1G>C mutation mainly caused exon 33 skipping. Our findings indicate that different nucleotide substitutions at the same residue can cause different splicing effects, which may contribute to the variable phenotype of Alport syndrome.

Silencing of long non‑coding antisense RNA brain‑derived neurotrophic factor attenuates hypoxia/ischemia‑induced neonatal brain injury

Hypoxic/ischemic (HI) brain damage (HIBD) is a major cause of acute neonatal brain injury, leading to high mortality and serious neurological deficits. The antisense RNA of brain-derived neurotrophic factor (BDNF-AS) is transcribed from the opposite strand of the BDNF gene. The aim of the present study was to investigate the role of BDNF-AS in HI-induced neuronal cell injury in vivo and in vitro. Reverse transcription-quantitative PCR (RT-qPCR) assays indicated that BDNF-AS expression was significantly upregulated in HI-injured neonatal brains and hippocampal neurons. However, BDNF expression was downregulated in HI-injured neonatal brains and hippocampal neurons. Cell Counting Kit-8 assays, Hoechst staining, calcein-AM/PI staining, immunostaining, water maze tests and rotarod tests demonstrated that BDNF-AS silencing protected against hypoxia-induced primary hippocampal neuron injury in vitro and HI-induced brain injury in vivo. Mechanistically, RT-qPCR assays and western blotting indicated that BDNF-AS silencing led to increased expression of BDNF and activated the BDNF-mediated signaling pathway, as demonstrated by increased expression levels of BDNF, phosphorylated-Akt and phosphorylated-tropomyosin receptor kinase B. Collectively, the present study provides important insights into the pathogenesis of HIBD, and it was indicated that BDNF-AS silencing may be a promising approach for the treatment of neonatal HIBD.

Long non-coding RNA Snhg3 protects against hypoxia/ischemia-induced neonatal brain injury

Hypoxic-ischemic brain damage (HIBD) is a major cause of morbidity and mortality in the preterm and term infant. However, the precise mechanism of HIBD remains largely elusive. As a newly discovered long non-coding RNA, small nucleolar RNA host gene 3 (Snhg3) has shown its important roles in cell apoptosis, proliferation, and disease development. In this study, we determined the role of Snhg3 in the pathogenesis of HIBD. Snhg3 expression was significantly down-regulated in the neonatal brain and primary hippocampal cells response to hypoxic/ischemic stress. Snhg3 overexpression protected against hypoxic/ischemic-induced brain injury in vivo and hippocampal cell injury in vitro. Snhg3 acted as the sponge of miR-196 in the hippocampal cells by regulating the expression of miR-196 target genes, XIAP and CAAP1. Moreover, Snhg3 overexpression decreased brain infarct size and ameliorated hypoxic-ischemic neonatal brain damage. This study suggests that Snhg3 is a potential target for the treatment of HIBD.

Usefulness of mizoribine administration in children with frequently relapsing nephrotic syndrome, and the relationship between pharmacokinetic parameters and efficacy: a multicenter prospective cohort study in China

BACKGROUND

Mizoribine (MZR) is an immunosuppressant used to treat adult nephropathy. There is little experience with the drug in treating Chinese children with frequently relapsing nephrotic syndrome (FRNS). We investigated the efficacy and safety for treating MZR with FRNS. Furthermore, the relationship between efficacy and serum concentration was investigated.

METHODS

A prospective multicenter observational 12-month study was performed for evaluating the usefulness of MZR with FRNS. Serum MZR concentration was measured, and the relationships between pharmacokinetic parameters (C_max, AUC), number of relapses, and urinary protein were evaluated.

RESULTS

Eighty-two pediatric patients from four hospitals were treated with MZR and prednisone. MZR treatment significantly reduced the number of relapses and steroid doses. A correlation between pharmacokinetic parameters and relapses was observed, which fits well with the sigmoidal E_max model. Even in the relationship between pharmacokinetic parameters and urinary proteins, it was recognized that there was a threshold in the pharmacokinetic parameters for the therapeutic effect similar to the results obtained with the sigmoidal E_max model. Eleven patients (13.4%) experienced mild adverse events.

CONCLUSIONS

MZR therapy was effective in reducing the number of relapses and steroid doses. No severe adverse reactions were observed. Therapeutically effective serum concentrations were estimated to be C_max ≥ about 2 μg/mL or AUC ≥ about 10 μg h/mL. MZR and steroid treatment were effective and safe for pediatric FRNS.

[A multicenter study of reference intervals for 15 laboratory parameters in Chinese children]

Objective: To establish comprehensive laboratory reference intervals for Chinese children. Methods: This was a cross-sectional multicenter study. From June 2013 to December 2014, eligible healthy children aged from 6-month to 17-year were enrolled from 20 medical centers with informed consent. They were assessed by physical examination, questionnaire survey and abdominal ultrasound for eligibility. Fasting blood samples were collected and delivered to central laboratory. Measurements of 15 clinical laboratory parameters were performed, including estradiol (E2), testosterone(T), luteinizing hormone(LH), follicle-stimulating hormone(FSH), alanine transaminase(ALT), serum creatinine(Scr), cystatin C, immunoglobulin A(IgA), immunoglobulin G(IgG), immunoglobulin M(IgM), complement (C3, C4), alkaline phosphatase(ALP), uric acid(UA) and creatine kinase(CK). Reference intervals were established according to central 95% confidence intervals for reference population, stratified by age and sex. Results: In total, 2 259 children were enrolled. Finally, 1 648 children were eligible for this study, including 830 boys and 818 girls, at a mean age of 7.4 years. Age- and sex- specific reference intervals have been established for the parameters. Reference intervals of sex hormones increased gradually with age. Concentrations of ALT, cystatin C, ALP and CK were higher in children under 2 years old. Serum levels of sex hormones, creatinine, immunoglobin, CK, ALP and urea increased rapidly in adolescence, with significant sex difference. In addition, reference intervals were variable depending on assay methods. Concentrations of ALT detected by reagents with pyridoxal 5'-phosphate(PLP) were higher than those detected by reagents without PLP. Compared with enzymatic method, Jaffe assay always got higher results of serum creatinine, especially in children younger than 9 years old. Conclusion: This study established age- and sex- specific reference intervals, for 15 clinical laboratory parameters based on defined healthy children.

High-throughput sequencing analysis of lncRNAs in hippocampus tissues with hypoxic-ischemic brain damage

LncRNAs abundantly expressed in the brain have vital and wide-ranging functions in different biological processes. However, little is currently known regarding the influence of lncRNAs in developing brains after hypoxic-ischemic brain damage (HIBD). In this study, to investigate the lncRNAs expression signatures and the co-expression network of lncRNAs and mRNAs in the brain after HIBD, we established a neonatal rat HIBD model and detected the expression profiles of lncRNAs in the HIBD brain and a sham control using high-throughput sequencing. Further, highly differentially expressed lncRNAs were selected and validated by qRT-PCR. Finally, the biological functions of the selected lncRNAs were investigated by over-expressing or silencing the target genes through lentivirus transfection in hippocampal neuron cells. Our results revealed that the expression profile of lncRNAs was dramatically different between the HIBD brains and the sham control, showing as the aberrant expression of 617 lncRNA transcripts and 441 mRNA transcripts at 24 hours after HIBD. GO and KEGG analyses indicated that the differentially expressed mRNAs were mostly involved in the apoptosis signaling pathway. After validating the expression of 8 randomly selected lncRNA transcripts by qRT-PCR, we found that the TNFRSF17 gene (ID: ENSRNOG00000021987) was down-regulated in HI brains. After stable over-expression and silencing of TNFRSF17, the apoptosis rate of hippocampal neuron cells exhibited obvious changes under hypoxia or normaxia. The over-expression of TNFRSF17 could significantly up-regulate Bcl-2 but down-regulate Bax, caspase-3, and caspase-9 at the mRNA and protein levels, while the silencing of TNFRSF17 led to just the opposite phenomenon. Notably, the regulation effects of TNFRSF17 on apoptotic related genes and proteins under hypoxia were more obvious than those under normaxia. Moreover, the over-expression of TNFRSF17 reduced the apoptotic rate, but the loss of TNFRSF17 led to a high rate of apoptosis under hypoxia. Taken together, the silencing of TNFRSF17 exacerbated, while over-expression attenuated, neuron apoptosis induced by HI injury, suggesting that TNFRSF17 may be a target for the prognosis, diagnosis, and treatment of HIBD.

The COL4A3 and COL4A4 Digenic Mutations in cis Result in Benign Familial Hematuria in a Large Chinese Family

Mutations in the COL4A5 gene result in X-linked Alport syndrome, homozygous or compound heterozygous mutations in COL4A3 or COL4A4 are responsible for autosomal recessive Alport syndrome, and heterozygous mutations in COL4A3 or COL4A4 cause autosomal dominant Alport syndrome or benign familial hematuria. Recently, the existence of a digenic inheritance in Alport syndrome has been demonstrated. We here report heterozygous COL4A3 and COL4A4 digenic mutations in cis responsible for benign familial hematuria. Using bioinformatics analyses and pedigree verification, we showed that COL4A4 c.1471C>T and COL4A3 c.3418 + 1G>T variants in cis are pathogenic and co-segregate with the benign familial hematuria. This result suggests that COL4A3 and COL4A4 digenic mutations in cis mimicking an autosomal dominant inheritance should be considered as a novel inheritance pattern of benign familial hematuria, although the disease-causing mechanism remains unknown.

Three Novel Heterozygous COL4A4 Mutations Result in Three Different Collagen Type IV Kidney Disease Phenotypes

Thin basement membrane nephropathy (TBMN), autosomal dominant Alport syndrome (ADAS), and focal segmental glomerulosclerosis (FSGS) are kidney diseases that differ in clinical diagnosis, treatment, and prognosis. Nevertheless, they may result from the same causative genes. Here, we report 3 COL4A4 heterozygous mutations (p.Gly208Arg, p.Ser513Glufs*2, and p.Met1617Cysfs*39) that lead to 3 different collagen type IV kidney disease phenotypes, manifesting as TBMN, ADAS, and FSGS. Using bioinformatics analyses and pedigree verification, we show that these novel variants are pathogenetic and cosegregate with TBMN, ADAS, and FSGS. Furthermore, we found that the collagen type IV-associated kidney disease phenotypes are heterogeneous, with overlapping pathology and genetic mutations. We propose that COL4A4-associated TBMN, ADAS, and FSGS should be considered as collagen type IV kidney disease subtypes that represent different phases of disease progression.

MicroRNA‑106b regulates skeletal muscle insulin sensitivity and glucose homeostasis by targeting mitofusion‑2

MicroRNA‑106b (miR‑106b) is reported to be closely associated with skeletal muscle insulin resistance. The present study further investigated the role of miR‑106b in skeletal muscle insulin sensitivity and glucose homeostasis in vivo. Mice were randomly divided into 4 groups and infected with lentivirus expressing miR‑106b (miR‑106b mice), miR‑106b sponge (miR‑106b inhibition mice) or the corresponding empty vectors. Mitofusion‑2 (Mfn2) protein expression levels and glucose transporter (Glut)‑4 protein translocation were significantly reduced in the muscle of miR‑106b mice, whereas they were unaffected in miR‑106b inhibition mice. miR‑106b mice had significantly increased blood glucose levels following 12 h of fasting and impaired glucose tolerance, whereas miR‑106b inhibition mice had no significant alterations in fasting blood glucose levels and glucose tolerance. In vitro, the suppressive effect of miR‑106b on glucose uptake and Glut4 translocation was completely inhibited in C2C12 myotubes infected with Mfn2 plasmids. Following treatment of C2C12 myotubes with Mfn2 small interfering RNA, miR‑106b inhibition consistently increased Mfn2 protein levels and improved glucose uptake and Glut4 translocation. These results indicated that miR‑106b targeted Mfn2 and regulated skeletal muscle insulin sensitivity and glucose tolerance. Therefore, increased miR‑106b expression may be a potential mechanism underlying insulin resistance and type 2 diabetes.

Silencing miR-106b improves palmitic acid-induced mitochondrial dysfunction and insulin resistance in skeletal myocytes

MicroRNA‑106b (miR‑106b) is reported to correlate closely with skeletal muscle insulin resistance. In the current study the effect of miR‑106b on palmitic acid (PA)‑induced mitochondrial dysfunction and insulin resistance was investigated in C2C12 myotubes via the silencing of miR‑106b. MiR‑106b expression was increased under PA treatment, while miR‑106b loss of function improved insulin sensitivity by upregulating its target mitofusin‑2 (Mfn2) in C2C12 myocytes. Furthermore, miR‑106b loss of function partly improved mitochondrial morphological lesions and increased the levels of mitochondial DNA and intracellular adenosine triphosphate that had been impaired by PA exposure in C2C12 myocytes. MiR‑106b loss of function attenuated the levels of intracellular reactive oxygen species (ROS), and upregulated the expression levels of the estrogen‑related receptor (ERR)‑α/peroxisome proliferative activated receptor γ coactivator (PGC)‑1α/Mfn2 axis under PA exposure. In addition, miR‑106b negatively regulated skeletal muscle mitochondrial function and insulin sensitivity under PA‑induced insulin resistance by targeting Mfn2, which may be associated with reduced ROS and upregulation of the ERR‑α/PGC‑1α/Mfn2 axis.

MicroRNA-106b induces mitochondrial dysfunction and insulin resistance in C2C12 myotubes by targeting mitofusin-2

MicroRNA-106b (miR-106b) is reported to correlate closely with skeletal muscle insulin resistance and type 2 diabetes. The aim of this study was to identify an mRNA targeted by miR-106b which regulates skeletal muscle insulin sensitivity. MiR-106b was found to target the 3' untranslated region (3' UTR) of mitofusin-2 (Mfn2) through miR-106b binding sites and to downregulate Mfn2 protein abundance at the post-transcriptional level by luciferase activity assay combined with mutational analysis and immunoblotting. Overexpression of miR-106b resulted in mitochondrial dysfunction and insulin resistance in C2C12 myotubes. MiR-106b was increased in insulin-resistant cultured C2C12 myotubes induced by TNF-α, and accompanied by increasing Mfn2 level, miR-106b loss of function improved mitochondrial function and insulin sensitivity impaired by TNF-α in C2C12 myotubes. In addition, both overexpression and downregulation of miR-106b upregulated peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and estrogen-related receptor (ERR)-α expression. MiR-106b targeted Mfn2 and regulated skeletal muscle mitochondrial function and insulin sensitivity. Therefor, Inhibition of miR-106b may be a potential new strategy for treating insulin resistance and type 2 diabetes.

Validation of the Oxford classification of IgA nephropathy for pediatric patients from China

Background

The Oxford classification of IgA nephropathy (IgAN) provides a useful tool for prediction of renal prognosis. However, the application of this classification in children with IgAN needs validation in different patient populations.

Methods

A total of 218 children with IgAN from 7 renal centers in China were enrolled. The inclusion criteria was similar to the original Oxford study.

Results

There were 98 patients (45%) with mesangial proliferation (M1), 51 patients (23%) with endocapillary proliferation (E1), 136 patients (62%) with segmental sclerosis/adhesion lesion (S1), 13 patients (6%) with moderate tubulointerstitial fibrosis (T1 26-50% of cortex scarred), and only 2 patients (1%) with severe tubulointerstitial fibrosis (T2, >50% of cortex scarred). During a median follow-up duration of 56 months, 24 children (12.4%) developed ESRD or 50% decline in renal function. In univariate COX analysis, we found that tubular atrophy/interstitial fibrosis (HR 4.3, 95%CI 1.8-10.5, P < 0.001) and segmental glomerulosclerosis (HR 9.2 1.2-68.6, P = 0.03) were significant predictors of renal outcome. However, mesangial hypercellularity, endocapillary proliferation, crescents, and necrosis were not associated with renal prognosis. In the multivariate COX regression model, none of these pathologic lesions were shown to be independent risk factors of unfavorable renal outcome except for tubular atrophy/interstitial fibrosis (HR 2.9, 95%CI 1.0-7.9 P = 0.04).

Conclusions

We confirmed tubular atrophy/interstitial fibrosis was the only feature independently associated with renal outcomes in Chinese children with IgAN.

Protective effects of sinomenine against doxorubicin-induced nephrosis in rats

Sinomenine (SN, 1) is a pure compound extracted from the Sinomenium acutum plant. We investigated the protective effects and mechanism of action of SN in a rat model of doxorubicin (DOX)-induced nephrosis. Nephrosis was induced by a single dose of 5 mg/kg DOX, and DOX-treated rats received a daily i.p. injection of 10 or 30 mg/kg SN, or saline (n = 6). Urine and serum biochemical parameters, serum TNF-α and IL-1β levels, nephrin, podocin, α-actinin-4, and peroxisome proliferator-activated receptor-α (PPAR-α) protein expression, and renal ultrastructure were examined at day 28. Compound 1 significantly attenuated the effect of DOX on urine and serum biochemical parameters. Electron microscopy demonstrated that 1 suppressed DOX-induced increases in foot process width. Compared with those in control rats, nephrin, podocin, and PPAR-α protein expressions decreased in the glomeruli of DOX-treated rats, and this effect was significantly attenuated by 1. However, no appreciable alterations were observed in the expression level of α-actinin-4. DOX significantly increased serum TNF-α and IL-1β compared with those in control rats, and 1 significantly reduced the serum levels of TNF-α and IL-1β. SN ameliorates DOX-induced nephrotic syndrome in rats, resulting in a modulation of renal nephrin, podocin expression, and thereby protecting podocytes from injury.

Modified Thoracoscopic versus Minimally Invasive Oesophagectomy in Curative Resection of Oesophageal Cancer

Conventional thoracoscopic oesophagectomy is time-consuming and requires sophisticated endoscopic skills. To reduce these problems we have modified the operating procedure, first by anastomosis of the oesophagus with the tubular stomach pulled up via the retrosternal route, followed by thoracoscopic oesophagectomy (modified thoracoscopic oesophagectomy). Outcomes were compared between the modified procedure and minimally invasive oesophagectomy. There were no significant differences in general preoperative clinical characteristics between the two patient groups. The modified thoracoscopic oesophagectomy group had significantly lower hospitalization expenses, significantly shorter operation times and significantly more lymph nodes removed compared with the minimally invasive oesophagectomy group, but there were no significant group differences in lengths of hospital and intensive care unit stays, morbidity and mortality. These results indicate that modified thoracoscopic oesophagectomy is feasible, simplifies operating procedures and reduces hospitalization expenses with acceptable morbidity.

UCP4 overexpression improves fatty acid oxidation and insulin sensitivity in L6 myocytes

Obesity, which is caused by energy uptake being greater than energy expenditure, is widely prevalent today. Currently, only a limited number of efficient interventional strategies are available for the prevention of obesity. Previous studies have shown that UCP4 transcription occurs at a considerable level in mouse skeletal muscle; however, the exact functions of UCP4 remain unclear. In this study, we investigated the effect of UCP4 on mitochondrial function and insulin sensitivity in mature L6 myocytes. UCP4 overexpression in L6 myocytes induced increased mitochondrial carnitine palmitoyltransferase 1A (CPT1A) and decreased citrate synthase (CS) mRNA in the basal condition (i.e., in the absence of insulin). UCP4 overexpression significantly improved insulin sensitivity, increased tyrosine phosphorylation of IRS-1 in the presence of insulin, and significantly reduced intracellular triglyceride (TG). Additionally, intracellular ATP content and mitochondrial membrane potential were downregulated. We also observed that intracellular ROS, mitochondrial morphology, and mitochondrial mtDNA copy number were maintained upon UCP4 expression, with no change in mitochondrial fusion and fission. In summary, our findings provide evidence to show that UCP4 overexpression reduced the insulin sensitivity and mitochondrial fatty acid oxidation of L6 myocytes. These findings support the notion that UCPs are ideal targets for treatment of insulin resistance.

Mitochondrial dysfunction is induced by high levels of glucose and free fatty acids in 3T3-L1 adipocytes

Hyperglycemia and high free fatty acids (FFAs) are two well-known characteristics of type 2 diabetes, and are also implicated in the etiology of insulin resistance. However, their roles in mitochondrial dysfunction of white adipocytes are not well-studied. In this study, we investigated the effects of high glucose (25 mM), high free fatty acids (FFAs, 1mM), or a combination of both high glucose+high FFAs on mitochondrial function in differentiated 3T3-L1 adipocytes after 48 h of treatment. We found that high glucose, high FFAs, or high glucose+high FFAs reduced insulin-stimulated glucose uptake in differentiated 3T3-L1 adipocytes. In addition, the mitochondria became smaller and more compact. Levels of the mitofusion protein mfn1 decreased and levels of the mitofission protein Drp1 increased as compared to controls. NRF1 was downregulated, and PGC-1 beta levels were diminished in the high glucose and high glucose+high FFAs conditions. Levels of PGC-1 alpha and mtTFA mRNA were greatly downregulated. No difference was found in the mitochondrial DNA (mtDNA) and intracellular ATP levels of treated cells compared to control cells. Cells treated with high glucose or high FFAs accumulated significant amounts of reactive oxygen species (ROS) and displayed a loss of the mitochondrial membrane potential. High glucose and high glucose+high FFAs led to similar decreases in intramitochondrial calcium concentration, although high FFAs had no effect. Therefore, high glucose and high FFAs can regulate insulin sensitivity, and mitochondrial dysfunction may occur in this process.

Mitochondrial dysfunction is induced by the overexpression of UCP4 in 3T3-L1 adipocytes

Uncoupling proteins (UCPs) belong to a superfamily of mitochondrial transporters that uncouple ATP synthesis from electron transport. We have previously shown that uncoupling protein 4 (UCP4) is differentially expressed in omental adipose tissue in diet-induced obese and normal rats. Overexpression of UCP4 promotes proliferation and inhibits apoptosis and differentiation of preadipocytes. In this work, we further characterized the effect of UCP4 on mitochondrial function in mature 3T3-L1 adipocytes. Transmission electron microscopy (TEM) showed that adipocytes overexpressing UCP4 displayed condensed mitochondria with twisted, condensed, and unclear cristae. Moreover, the loss of the mitochondrial membrane potential and intramitochondrial calcium was found. The adipocytes overexpressing UCP4 also showed decreased mitochondrial copy number (mtDNA) and lower mRNA expression of key factors in mitochondrial biogenesis, including PGC-1alpha and mtTFA. NRF-1 and ERRbeta levels were down-regulated, while NRF-2 levels were upregulated. In addition, UCP4 overexpression impaired mitochondrial fusion and fission, as indicated by decreased mitofusin mfn1, mfn2, and mitofission DRP1. When it came to total adipocytes, the UCP4 overexpressing adipocytes showed higher production reactive oxygen species and diminished levels of intracellular ATP. Furthermore, overexpression of UCP4 brought about impaired insulin sensitivity in adipocytes. UCP4 plays an important role in mitochondrial function and adipocyte insulin resistance. Its function deserves further attention.