Inhibition of RAC attenuates Adriamycin-induced podocyte injury

Minimal Change Disease (MCD), which is associated with podocyte injury, is the leading cause of nephrotic syndrome in children. A considerable number of patients experience relapses and require prolonged use of prednisone and immunosuppressants. Multi-drug resistance and frequent relapses can lead to disease progression to focal and segmental glomerulosclerosis (FSGS). To identify potential targets for therapy of podocyte injury, we examined microarray data of mRNAs in glomerular samples from both MCD patients and healthy donors, obtained from the GEO database. Differentially expressed genes (DEGs) were used to construct the protein-protein interactions (PPI) network through the application of the search tool for the retrieval of interacting genes (STRING) tool. The most connected genes in the network were ranked using cytoHubba. 16 hub genes were selected and validated by qRT-PCR. RAC2 was identified as a potential therapeutic target for further investigation. By downregulating RAC2, Adriamycin (ADR)-induced human podocytes (HPCs) injury was attenuated. EHT-1864, a small molecule inhibitor that targets the RAC (RAC1, RAC2, RAC3) family, proved to be more effective than RAC2 silencing in reducing HPCs injury. In conclusion, our research suggests that EHT-1864 may be a promising new molecular drug candidate for patients with MCD and FSGS.

Diagnostic value of adenohypophyseal MRI features in female children with precocious puberty

AIM

To evaluate the diagnostic value of adenohypophyseal magnetic resonance imaging (MRI) features for precocious puberty (PP) in female children and also to establish a non-invasive diagnostic approach in clinics.

MATERIALS AND METHODS

A total of 126 female children (37, 57, and 32 female children clinically diagnosed with central PP [CPP], incomplete PP [IPP], and controls, respectively) were enrolled in this study. Data were collected and analysed using analysis of variance. Pearson correlation and stepwise multivariate linear regression analysis were used to examine the association and build prediction models. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic efficacy.

RESULTS

The values of adenohypophysis volume (aPV), adenohypophysis height (aPH), and signal-intensity ratio (SIR), height, weight, and seven laboratory testing characteristics were correlated closely with the activation status of the hypothalamic-pituitary-gonad axis in the different groups (all p<0.05). Model 1 including aPV, weight, and aPH and Model 2 including SIR, aPV, and height were built to obtain predicted luteinising hormone (LH; R2 = 0.271) and LH/follicle stimulating hormone (FSH; R2 = 0.311). ROC analysis showed the predicted LH, predicted LH/FSH, and aPV were the top 3 best predictors in distinguishing CPP from controls (AUC = 0.969, 0.949, and 0.938) while predicted LH/FSH was the best predictor in distinguishing CPP from IPP and controls (AUC = 0.829 and 0.828).

CONCLUSION

The adenohypophysis volume itself and the prediction models including main adenohypophyseal MRI features increased diagnostic efficiency for PP and offered a non-invasive and credible diagnostic method.

Monogenic Causes Identified in 23.68% of Children with Steroid-Resistant Nephrotic Syndrome: A Single-Centre Study

Introduction

Steroid-resistant nephrotic syndrome (SRNS) is the second most common cause of end-stage kidney disease in children, mostly associated with focal segmental glomerulosclerosis (FSGS). Advances in genomic science have enabled the identification of causative variants in 20-30% of SRNS patients.

Methods

We used whole exome sequencing to explore the genetic causes of SRNS in children. Totally, 101 patients with SRNS and 13 patients with nephrotic proteinuria and FSGS were retrospectively enrolled in our hospital between 2018 and 2022. For the known monogenic causes analysis, we generated a known SRNS gene list of 71 genes through reviewing the OMIM database and literature.

Results

Causative variants were identified in 23.68% of our cohort, and the most frequently mutated genes in our cohort were WT1 (7/27), NPHS1 (3/27), ADCK4 (3/27), and ANLN (2/27). Five patients carried variants in phenocopy genes, including MYH9, MAFB, TTC21B, AGRN, and FAT4. The variant detection rate was the highest in the two subtype groups with congenital nephrotic syndrome and syndromic SRNS. In total, 68.75% of variants we identified were novel and have not been previously reported in the literature.

Conclusion

Comprehensive genetic analysis is key to realizing the clinical benefits of a genetic diagnosis. We suggest that all children with SRNS undergo genetic testing, especially those with early-onset and extrarenal phenotypes.

Correlation between iron metabolism indicators and programmed death ligand 1 expression in advanced non-small cell lung cancer

The dysregulation of iron metabolism is closely linked to the onset and progression of lung cancer. This study aimed to explore the association between iron metabolism indicators (serum iron, transferrin, ferritin) and the expression level of programmed death factor ligand 1 in primary lesions of advanced non-small cell lung cancer. A cohort of 62 patients, including 42 men and 20 women, was recruited from October 2022 to July 2023, all diagnosed with advanced non-small cell lung cancer, confirmed through radiographic imaging and histopathological analysis. Comprehensive clinical data (such as gender, age, familial lung cancer history, smoking history, pathological classification, clinical stage, etc.) and concentrations of fasting serum iron, transferrin, and ferritin were collected. Patients were categorized into PD-L1 negative (<1% expression) and programmed death ligand 1 (PD-L1) positive (≥1% expression) groups based on PD-L1 expression levels in tumor tissues. Subsequently, the correlation between levels of serum iron, transferrin, ferritin, and PD-L1 expression in advanced non-small cell lung cancer were examined. Patients in the PD-L1 positive group exhibited lower levels of peripheral serum iron and transferrin compared to those in the PD-L1 negative group (P<0.05). For patients exhibiting positive PD-L1 expression, a negative correlation was observed between PD-L1 expression and both serum iron and transferrin levels (r = -0.465, P=0.003; r = -0.447, P=0.005), and a positive correlation was noted between PD-L1 expression and ferritin levels (r=0.393, P=0.015). We conclude that in In patients with advanced non-small cell lung cancer, serum iron and transferrin levels can serve as partial predictors of PD-L1 expression; among those positive for PD-L1, a significant association exists between indicators of iron metabolism and PD-L1 expression.

Role of cuproptosis in understanding diseases

Cell death is involved in a wide range of physiological and pathological processes. Recently, the term "cuproptosis" was coined to describe a novel type of cell death. This type of cell death, characterized by copper accumulation and proteotoxic stress, is a copper-dependent manner of death. Despite the progress achieved toward a better understanding of cuproptosis, mechanisms and related signaling pathways in physiology and pathology across various diseases remain to be proved. This mini review summarizes current research on cuproptosis and diseases, providing insights into prospective clinical therapies via targeting cuproptosis.

Compound heterozygous variants in WLS gene causes Zaki syndrome

Biallelic Wnt ligand secretion mediator (WLS gene) variants are associated with Zaki syndrome (OMIM: #619648). Here, we report the first case with Zaki syndrome in the Chinese population. Whole-exome gene sequencing (WES) identified compound heterozygous variants in the WLS gene (c.1427A > G; p.Tyr476Cys and c.415C > T, p.Arg139Cys; NM_001002292) in a 16-year-old boy presenting with facial dysmorphism, astigmatism, renal agenesis, and cryptorchidism. In vitro functional characterization showed that the two variants led to decreased WLS production and secretion of WNT3A, eventually affecting the WNT signal. We also found that the decreased mutant WLS expression can be rescued by 4-Phenylbutyric acid (4-PBA).

Reduction of NADPH oxidase 4 in adipocytes contributes to the anti-obesity effect of dihydroartemisinin

Artemisinin derivatives have been found to have anti-obesity effects recently, but the mechanism is still controversial. Herein, long-term DHA treatment in obese mice significantly reduced the body weight and improved glucose metabolism. However, short-term DHA treatment did not affect glucose metabolism in obese mice, suggesting that the improved glucose metabolism in mice with DHA treatment could be secondary to body weight reduction. Consistent with previous reports, we observed that DHA inhibited the differentiation of adipocytes. Mechanistically, DHA significantly reduced the expression of NADPH oxidase 4 (NOX4) in white adipose tissue (WAT) of mice and differentiated adipocytes, and using NOX4 siRNA or the NOX4 inhibitor GKT137831 significantly attenuated adipocyte differentiation. Over-expression of NOX4 partially reversed the inhibition effect of DHA on adipogenic differentiation of preadipocytes. In addition, targeted proteomics analysis showed that DHA improved the abnormality of metabolic pathways. In conclusion, DHA significantly reduced fat mass and improved glucose metabolism in obese mice, possibly by inhibiting NOX4 expression to suppress adipocyte differentiation and lipid accumulation in adipocytes.

The identification of a novel CCNQ gene tail extension variant contributing to syndactyly, telecanthus and anogenital and renal malformations syndrome

The "toe syndactyly, telecanthus and anogenital and renal malformations" (STAR) syndrome is a rare X-linked dominant inherited kidney ciliopathy caused by CCNQ gene mutations. Here, we investigated the genotype and phenotype in the first two twin sisters with a novel tail extension CCNQ variant in Asia. Genetic variants of the pedigree were screened using whole-exome sequence analysis and validated by direct Sanger sequencing. The genetic function was investigated through cultured cells and zebrafish embryos transfected with mutant. The proband is suffered from end-stage renal disease, telecanthus, scoliosis, anal atresia, bilateral hydronephrosis pyeloureter dilation and hearing loss, while her twin sister had milder phenotypes. A novel heterozygous variant c.502_518delinsA (p.Val168SerfsTer173) in CCNQ gene was identified in the twins and their asymptomatic mosaic mother. The concurrent deletion of 17 bases and insertion of one base variant led to the loss of 5 amino acids, subsequently caused a 96 more amino acids tail extension delaying the appearance of stop codon. The loss-of-function variant of CCNQ not only led to the impaired expression of cyclin M but also increased the binding affinity of CDK10-cyclin M complex, which is different from the previous study. The research expanded the genotypic and phenotypic spectrum of STAR syndrome.

Association of body mass index and intestinal (faecal) Streptococcus in adults in Xining city, China P.R

Body mass index (BMI) and gut microbiota show significant interaction, but most studies on the relationship between BMI and gut microbiota have been done in Western countries. Relationships that are also identified in other cultural backgrounds are likely to have functional importance. Hence here we explore gut microbiota in adults living in Xining city (China P.R.) and relate results to subject BMI. Analysis of bacterial 16s rRNA gene was performed on faecal samples from participants with normal-weight (n=24), overweight (n=24), obesity (n=11) and type 2 diabetes (T2D) (n=8). The results show that unweighted but not weighted Unifrac distance was significantly different when gut microbiota composition was compared between the groups. Importantly, the genus Streptococcus was remarkably decreased in both obese subjects and subjects suffering from T2D, as compared to normal-weight subjects. Accordingly, strong association was identified between the genus Streptococcus and BMI and especially Streptococcus salivarius subsp. thermophiles was a major contributor in this respect. As previous studies have shown that Streptococcus salivarius subsp. thermophiles is also negatively associated with obesity in Western cohorts, our results suggest that this species is a potential probiotic for the prevention of obesity and related disorders.

Hemoperfusion and intravenous immunoglobulins for refractory gastrointestinal involvement in pediatric Henoch-Schönlein purpura: a single-center retrospective cohort study

BACKGROUND

Henoch-Schönlein purpura (HSP) with refractory gastrointestinal (GI) symptoms is always difficult to handle because of its resistance to supportive therapies and glucocorticoid. This study aimed to evaluate the efficacy of hemoperfusion (HP) and intravenous immunoglobulins (IVIG) therapies in this population.

METHODS

Sixty-four HSP patients with refractory GI involvement (R-GI group) and 64 cases with mild GI symptoms (control group) were retrospectively analyzed in our center from March 2016 to October 2019. In R-GI group, 42 cases (subgroup A) were treated with IVIG and steroid, 13 cases (subgroup B) used HP and steroid, 9 cases (subgroup C) executed a combination of IVIG, HP and steroid. Demographic characteristics, clinical features, laboratory indexes and treatment outcomes were recorded. t-test, One-way ANOVA, Mann-Whitney U test, and multivariate logistic regression were used in comparing differences among subgroups and predicting independent risk factors.

RESULTS

Compared with the control group, R-GI cases experienced higher risk of renal involvement (P = 0.000), more steroid exposure (P = 0.000), six times expenses (P = 0.000) and 2.3 times length of hospitalization (P = 0.000). The independent risk factors of R-GI group were elevated neutrophils (OR 1.250 [95% CI 1.130-1.383]) and the percentage of B lymphocytes (OR 1.100 [95% CI 1.026-1.179]) as well as decreased IgG (OR 0.847 [95% CI 0.732-0.98]). In R-GI group, increased age (OR 1.039 [95% CI 1.016-1.062]) and IgM (OR 5.994 [95% CI 1.403-27.611]) were verified to be risk factors of HSP nephritis. All three subgroups could alleviate the symptoms effectively. Compared with those in subgroup A, patients in subgroup B were elder (P = 0.004), had less relapse (P = 0.002), steroid exposure (P = 0.033) and expenses (P = 0.031), more significant decrease of WBC (P = 0.026) after treatment.

CONCLUSION

The HSP with refractory GI involvement had much higher risk of medical burden and renal involvement. Both IVIG and HP therapies could ameliorate refractory GI symptoms efficiently. HP therapy tended to reduce the relapse, costs and steroid exposure in its audiences who were cooperated and with stable hemodynamics, while IVIG had better use in younger children.

[Advances of enhancers in regulating craniomaxillofacial development in mammals]

As a key regulatory element of gene differential expression, enhancer plays a crucial role in craniomaxillofacial development through regulating the spatiotemporal expression of target genes to promote tissue-specific differentiation. With the development of CRISPR and chromosome conformation capture technique, the function of enhancer and its regulatory mechanism has been explored in depth. This paper gave a systematic review on the mechanism of enhancer regulating target gene expression and the role of enhancer in oral craniofacial development and malformation.

Maintaining homeostasis of mitochondria and endoplasmic reticulum with NSC228155 alleviates cisplatin-induced acute kidney injury

Acute kidney injury (AKI) is a common complication of hospitalization with high mortality. Approximately 30% of patients receiving cisplatin, the first-line chemotherapy treatment, develop AKI. NSC228155 is a novel compound with potential anti-cancer and anti-bacterial effects. Its therapeutic efficacy in other diseases is unclear. In the present study, we investigated the effect of NSC228155 on cisplatin-induced AKI. The mice were consecutively treated with 2.5 mg/kg of NSC228155 for five days and injected with cisplatin (22 mg/kg) via intraperitoneal injection on day three. NSC228155 strikingly improved the renal function by decreasing the serum creatinine by 52.6% in the cisplatin-induced AKI mice model. Pathologically, NSC228155 profoundly alleviated the tubular damage in Periodic Acid-Schiff staining, and significantly reduced the expression of tubular injury markers and apoptosis in the cisplatin-injured mice kidneys. NSC228155 effectively restored the mitochondrial homeostasis by decreasing damaged mitochondria, activating signals for mitochondrial dynamics and recycling, and corrected mitochondrial dysfunction in ATP production and oxidative stress in the cisplatin model. Transcriptomics and metabolomics analysis on the mice renal cortex suggested that NSC228155 profoundly corrected energy metabolism, especially citrate cycle-related pathways, oxidative stress, and endoplasmic reticulum (ER) stress in the cisplatin-induced AKI kidneys. NSC228155 effectively inhibited ER stress induced by cisplatin or tunicamycin in mice kidneys and HK-2 cells. Co-treatment of NSC228155 with 4-phenylbutyrate or MnTBAP showed a similar therapeutic effect in AKI as the inhibitors or NSC228155 alone did, and corrected the mitochondrial dysfunction and ER stress, respectively, indicating the crosstalk between ER and mitochondria played essential roles in the therapeutic effect of NSC228155 in AKI. Together, these results consistently demonstrated that NSC228155 alleviated cisplatin-induced AKI by restoring the homeostasis in mitochondria and ER, suggesting a therapeutic potential and perhaps a novel strategy for drug discovery.

Genetic Variations and Clinical Features of NPHS1-Related Nephrotic Syndrome in Chinese Children: A Multicenter, Retrospective Study

Introduction: Few studies have addressed the genetic spectrum of NPHS1 variants in Chinese children with nephrotic syndrome. In this multicenter study, the clinical manifestations and features of NPHS1 variants in Chinese children with nephrotic syndrome were researched. Method: Genotypical and phenotypical data from 30 children affected by NPHS1 variants were collected from a multicenter registration system in China and analyzed retrospectively. Results: The patients were divided into two groups: congenital nephrotic syndrome (CNS [n = 24]) and non-CNS (early onset nephrotic syndrome [n = 6]). Renal biopsy was performed on four patients in the non-CNS group, revealing minimal change disease in three and focal segmental glomerulosclerosis in one. A total of 61 NPHS1 variants were detected, involving 25 novel variants. The "recurrent variants" included c.928G>A(p.Asp310Asn) in eight patients with CNS, followed by c.616C>A(p.Pro206Thr) in four, and c.2207T>C (p.Val736Ala) in three. Steroid treatment was applied in 29.2% (7/24)of the patients in the CNS group and 50% (3/6) of the patients in the non-CNS group. One patient in each group experienced complete remission but relapsed subsequently. Immunosuppressants were administered to three patients in the non-CNS group, eliciting an effective response. In the CNS group, three patients underwent renal transplantation and six died mainly from infection. Conclusion: Variants of NPHS1 cause CNS and early childhood-onset nephrotic syndrome. NPHS1 variants in Chinese individuals with nephrotic syndrome (NS) were mainly compound heterozygous variants, and c.928G>A(p.Asp310Asn) in exon 8 may act as a recurrent variant in the Chinese population, followed by c.616C>A(p.Pro206Thr) in exon 6. Steroids and immunosuppressants may be effective in selected patients.

SIRT1 Alleviates Aldosterone-Induced Podocyte Injury by Suppressing Mitochondrial Dysfunction and NLRP3 Inflammasome Activation

BACKGROUND

Podocyte injury contributes to progressive glomerulosclerosis. Previously, we demonstrated the important role of the NLR family pyrin domain containing 3 (NLRP3) inflammasome in mediating the podocyte injury induced by aldosterone. Silent mating type information regulation 2 homolog 1 (SIRT1) is an NAD+-dependent deacetylase that is associated with the regulation of cellular inflammation. However, whether the activation of the NLRP3 inflammasome in podocytes is regulated by SIRT1, and the mechanism involved, remains unknown.

METHODS

In this study, we detected SIRT1 expression in patients with podocyte disease and performed an aldosterone infusion model in podocyte-specific Sirt1 knockout mice. In cultured podocytes, we used plasmids to overexpress SIRT1 and treated the podocyte with aldosterone.

RESULTS

SIRT1 was significantly decreased in the glomeruli of patients with podocyte disease. Sirt1-deficient mice showed significant urinary albumin excretion after aldosterone infusion, and the severity of the glomerular injury was significantly greater in podocyte-specific Sirt1 knockout mice than in the wild-type mice. Moreover, podocyte conditional Sirt1 knockout aggravated NLRP3 inflammasome activation and mitochondrial dysfunction (MtD). In vitro, overexpression of SIRT1 inhibited NLRP3 activation, protected against MtD and podocyte injury.

CONCLUSION

Taken together, these findings revealed a novel regulatory mechanism of the NLRP3 inflammasome by SIRT1 by promoting mitochondrial function, which provides some potential targets for the treatment of glomerular diseases.

Multi-centre study of the clinical features and gene variant spectrum of Gitelman syndrome in Chinese children

Based on the Chinese Children Genetic Kidney Disease Database (CCGKDD), we established a pediatric Gitelman syndrome (GS) cohort to explore the phenotype and genotype characteristics. Thirty-two patients with SLC12A3 gene variants were collected. Five cases (16%) were homozygous, 16 (50%) were compound heterozygous, 10 (31%) carried only a single variant, and the other one harbored two de novo variants beyond classification. p.(T60M) was found in eight patients. The average diagnosis age was 7.79 ± 3.54 years. A total of 31% of the patients were asymptomatic. Muscle weakness was the most common symptom, accounting for 50%. Earlier age of onset (4.06 ± 1.17 yr vs. 8.10 ± 3.46 yr vs. 8.61 ± 3.56 yr, p< 0.05) and lower urinary calcium-creatinine ratio (p = 0.024) were found in the homozygous group than those in the heterozygous and compound heterozygous group. Patients with p.(T60M) variant had an earlier age of onset (4.01 ± 2.83 yr vs. 6.92 ± 3.07 yr, p = 0.025) and lower urinary calcium-creatinine ratio (p = 0.056). Thus, more than 30% of GS children have no clinical symptoms. Homozygous variant and the p.(T60M) variant may be associated with earlier onset and lower urinary calcium excretion in Chinese pediatric GS.

MicroRNA-214 targets COX-2 to antagonize indoxyl sulfate (IS)-induced endothelial cell apoptosis

Cardiovascular disease (CVD) serves as the major cause of mortality in chronic kidney disease (CKD) patients. The injury of endothelium associated with the long-term challenge of uremic toxins including the toxic indoxyl sulfate (IS) is one of key pathological factors leading to CVD. However, the mechanisms of uremic toxins, especially the IS, resulting in endothelial injury, remain unclear. miR-214 was reported to contribute to the pathogenesis of cardiovascular diseases, while its role in IS-induced endothelial cell apoptosis is unknown. In this study, we investigated the role of microRNA-214 (miR-214) in IS-induced endothelial cell apoptosis and the underlying mechanisms using mouse aortic endothelial cells (MAECs). Following IS treatment, miR-214 was significantly downregulated in MAECs in line with enhanced cell apoptosis. Meanwhile, COX-2 was upregulated at both mRNA and protein levels along with increased secretion of PGE₂ in medium. To define the role of miR-214 in IS-induced endothelial cell apoptosis, we modulated miR-214 level in MAECs and found that overexpression of miR-214 markedly attenuated endothelial cell apoptosis, while antagonism of miR-214 deteriorated cell death after IS challenge. Further analyses confirmed that COX-2 is a target gene of miR-214, and the inhibition of COX-2 by a specific COX-2 inhibitor NS-398 strikingly attenuated IS-induced endothelial cell apoptosis along with a significant blockade of PGE₂ secretion. In conclusion, this study demonstrated an important role of miR-214 in protecting against endothelial cell damage induced by IS possibly by direct downregulation of COX-2/PGE₂ axis.

Functional Characterization of PHEX Gene Variants in Children With X-Linked Hypophosphatemic Rickets Shows No Evidence of Genotype-Phenotype Correlation

X-linked hypophosphatemia (XLHR) is caused by loss-of-function mutations in the phosphate regulating endopeptidase homolog X-linked (PHEX) gene. Considerable controversy exists regarding genotype-phenotype correlations in XLHR. The present study describes the clinical features and molecular genetic bases of 53 pediatric patients with XLHR. Overall, 47 different mutations were identified, of which 27 were not previously described in the literature or entered in the Human Gene Mutation Database (HGMD). A high prevalence (72.34%) of truncating variants was observed in XLHR patients. The clinical presentation and severity of XLHR did not show an evident correlation between the truncating and non-truncating mutation types in our cohort. To further delineate the characteristics of PHEX variants underlying this nonsignificant trend, we assessed the effects of 10 PHEX variants on protein expression, cellular trafficking, and endopeptidase activity. Our results showed that the nonsense mutations p.Arg567*, p.Gln714*, and p.Arg747* caused a reduction of protein molecular weight and a trafficking defect. Among seven non-truncating mutations, the p.Cys77Tyr, p.Cys85Ser, p.Ile281Lys, p.Ile333del, p.Ala514Pro, and p.Gly572Ser mutants were not secreted into the medium and remained trapped inside cells in an immature form, whereas the p.Gly553Glu mutant was terminally glycosylated and secreted into the medium. We further assessed the endopeptidase activity of the p.Gly553Glu mutant using a quenched fluorogenic peptide substrate and revealed that the activity of p.Gly553Glu significantly reduced to 13% compared with the wild type, which indicated disruption of catalytic function. These data not only support the clinical results showing no correlation between disease severity and the type of PHEX mutation but also provide helpful molecular insights into the pathogenesis of XLHR. © 2020 American Society for Bone and Mineral Research.

miR-214 Protects Against Uric Acid-Induced Endothelial Cell Apoptosis

Background: Uric acid (UA) has been reported to be an important risk factor for cardiovascular diseases and can cause endothelial cell apoptosis through unclear mechanisms. Accumulating evidence has demonstrated that miR-214 plays a pivotal role in the pathogenesis of cardiovascular diseases. This study was to investigate the role of miR-214 in UA-induced endothelial cell apoptosis and the underlying mechanism.

Material and methods: We enrolled 30 patients with hyperuricemia and 32 healthy controls and analyzed the levels of miR-214 in the serum of the participants. Then mouse aorta endothelial cells (MAECs) were treated with UA to induce cell apoptosis. An miR-214 mimic and a specific COX-2 inhibitor (NS398) were used to confirm the roles of these molecules in mediating UA-induced MAEC apoptosis or COX-2/PGE₂ cascade activation.

Results: A significant reduction in circulating miR-214 in the hyperuricemia patients compared with the healthy controls, along with a negative correlation with UA levels was observed. In the MAECs, UA treatment strikingly increased apoptosis as shown by the upregulation of BAX and cleaved Caspase-3 and the increased number of apoptotic cells. Interestingly, the expression of COX-2 was also upregulated at both the protein and mRNA levels during UA-induced cell apoptosis. In addition, an miR-214 mimic blocked UA-induced MAEC apoptosis, COX-2 induction and PGE₂ secretion. The inhibition of COX-2 markedly ameliorated UA-induced apoptotic response and PGE₂ production in MAECs. Luciferase activity assays further confirmed that COX-2 is a target gene of miR-214 in endothelial cells.

Conclusion: We concluded that miR-214 could alleviate UA-induced MAEC apoptosis possibly by inhibiting the COX-2/PGE₂ cascade.

Splicing Characterization of CLCNKB Variants in Four Patients With Type III Bartter Syndrome

Objective

Type III Bartter syndrome (BS) is caused by loss-of-function mutations in the gene encoding basolateral chloride channel ClC-Kb (CLCNKB), and is characterized by hypokalemic metabolic alkalosis and hyperreninemic hyperaldosteronism. Here, we investigated the molecular defects in four Chinese children with clinical manifestations of Bartter syndrome.

Methods

The genomic DNA of the four patients was screened for gene variations using whole-exome sequencing (WES). The candidate variants were validated by direct Sanger sequencing. Quantitative PCR (qPCR) was subsequently performed to confirm the whole CLCNK gene deletion mutation. A minigene assay and reverse transcription PCR (RT-PCR) were performed to analyze the effect of splice variants in vitro.

Results

Our patients showed early onset age with hyponatremia, hypokalemia, hypochloremia, repeated vomiting and growth retardation, suggesting Bartter syndrome. Genetic analysis revealed that all patients carried compound heterozygous or homozygous truncating variants in the CLCNKB gene. In particular, we identified a novel nonsense variant c.239G > A (p.(Trp80*)), two splice site variants (c.1053-1 G > A and c.1228-2A > G), a whole gene deletion, and a novel synonymous variant c.228A > C (p.(Arg76Arg)) which located -2 bp from the 5′ splice donor site in exon 3. Furthermore, our in vitro minigene analysis revealed c.228A > C, c.1053-1G > A, and c.1228-2A > G cause the skipping of exon 3, exon 12, and exon 13, respectively.

Conclusion

Our results support that the whole CLCNKB gene deletion is the most common mutation in Chinese patients with type III BS, and truncating and whole gene deletion variants may account for a more severe phenotype of patients. We verified the pathogenic effect of three splicing variants (c.228A > C, c.1053-1G > A, and c.1228-2A > G) which disturbed the normal mRNA splicing, suggesting that splice variants play an important role in the molecular basis of type III BS, and careful molecular profiling of these patients will be essential for future effective personalized treatment options.

Whole-genome sequencing revealed an interstitial deletion encompassing OCRL and SMARCA1 gene in a patient with Lowe syndrome

Background

Lowe syndrome is a rare X‑linked syndrome that is characterized by involvement of the eyes, central nervous system, and kidneys. The aim of the present study was to determine the molecular basis of four patients with congenital cataract, infantile congenital hypotonia, and proximal renal tubular defect.

Methods

Four children who met the clinical manifestations of Lowe syndrome were enrolled in this study. Patients’ clinical information on eyes, central nervous system, kidneys, and family histories, etc., were reviewed and analyzed. After obtaining informed consent, we performed a mutation analysis of OCRL gene using direct sequencing. Because of failure of PCR amplification, low coverage shortread whole genome sequencing (CNVseq) analysis was performed on one proband. Real‐time PCR was subsequently performed to confirm the CNV that was detected from the CNVseq results.

Results

We identified three OCRL allelic variants, including two novel missense mutations (c.1423C>T/p.Pro475Ser, c.1502T>G/p.Ile501Ser) and one recurrent nonsense mutation (c.2464C>T/p.Arg822Ter). Various bioinformatic tools revealed scores associated with potential pathogenic effects for the two missense variants, and protein alignments revealed that both variants affected an amino acid highly conserved among species. Since deletion of the entire gene was suspected in a patient, CNVseq was used, identifying an interstitial deletion to approximately 190 kb, encompassing OCRL, and SMARCA1 gene. Moreover, the hemizygous CNV was confirmed by qPCR. Reviewing another case reported in the literature, we found that the deletion of OCRL and nearby genes may contribute to a more severe phenotype and premature death.

Conclusions

This is the first report of an interstitial deletion encompassing OCRL and SMARCA1 gene in Lowe syndrome. Our results expand the spectrum of mutations of the OCRL gene in Chinese population. Moreover, whole‐genome sequencing presents a comprehensive and reliable approach for detecting genomic copy number variation in patients or carriers in the family with rare inherited disorders.

Ultrafast extreme rejuvenation of metallic glasses by shock compression

Structural rejuvenation of glasses not only provides fundamental insights into their complicated dynamics but also extends their practical applications. However, it is formidably challenging to rejuvenate a glass on very short time scales. Here, we present the first experimental evidence that a specially designed shock compression technique can rapidly rejuvenate metallic glasses to extremely high-enthalpy states within a very short time scale of about 365 ± 8 ns. By controlling the shock stress amplitude, the shock-induced rejuvenation is successfully frozen at different degrees. The underlying structural disordering is quantitatively characterized by the anomalous boson heat capacity peak of glasses. A Deborah number, defined as a competition of time scales between the net structural disordering and the applied loading, is introduced to explain the observed ultrafast rejuvenation phenomena of metallic glasses.

Probiotics maintain intestinal secretory immunoglobulin A levels in healthy formula-fed infants: a randomised, double-blind, placebo-controlled study

Formula-fed infants are more susceptible to infectious diseases because they lack the maternal immune factors transferred from breast milk, while their own immune system is still immature. As timely probiotic administration was suggested to promote immune system development in formula-fed infants, this study aimed at assessing the safety and the effects of a probiotic supplement (Bifidobacterium infantis R0033, Bifidobacterium bifidum R0071, and Lactobacillus helveticus R0052) on mucosal immune competence and digestive function in formula-fed infants. Healthy infants (3.5-6 months old) were randomised to receive either probiotic- (n=66) or placebo-supplemented (n=66) formula once a day for four weeks. In the probiotics group, faecal secretory immunoglobulin A (SIgA) levels remained similar between visit 2 (baseline; V2) and visit 3 (end-of-treatment; V3), but decreased in the placebo group. Changes in SIgA levels following treatment (log₁₀ΔV3-V2 [95%CI]) between the probiotic and placebo groups were statistically significant (23 ng/dl [-57;102] and -137 ng/dl [-212;-62], respectively (P=0.0044; ANCOVA)). While log₁₀ΔV3-V2 [95%CI] for salivary SIgA levels increased in both groups, this trend was more pronounced in the probiotics than in the placebo group with an increase of 123 ng/dl [9;236] and 37 ng/dL [-72;147], respectively (P=0.2829; ANCOVA). The weekly average number of stools/day was significantly higher in the probiotics group compared to placebo during the last week of treatment for the per protocol population. There was no difference in microbiota composition or anthropometric parameters between groups. No serious adverse event was reported, and all adverse events were mild and unrelated to the product or study. Our results show that formula-fed infants receiving probiotics maintained higher faecal SIgA levels at the end of the four-week treatment period, suggesting a positive effect of probiotics on SIgA production. This study demonstrates the safety of this probiotic formulation in infants. Formula-fed infants may benefit from probiotics supplementation to sustain the development of mucosal immunity.

Inhibition of the mitochondrial complex-1 protects against carbon tetrachloride-induced acute liver injury

Mitochondrial dysfunction has been documented to play a crucial role in the pathogenesis of liver injury. In the present study, we investigated the role of rotenone, a mitochondrial complex-1 inhibitor, in carbon tetrachloride (CCl₄) -induced acute liver injury, as well as the underlying mechanisms. Before CCl₄ administration, the mice were pretreated with rotenone at a dose of 250 ppm in food for three days. Then CCl₄ was administered to the mice for 16 h by intraperitoneal injection. The liver injury, mitochondrial status, oxidative stress, and inflammation were examined. Strikingly, CCl₄ treatment markedly induced liver injury as shown by enhanced serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and morphological lesions (HE stating), which was significantly attenuated by rotenone treatment in line with the reduced activity of mitochondrial complex-1. Meanwhile, oxidative stress markers of malondialdehyde (MDA), 4-hydroxynonenal (HNE), and dihydroethidium (DHE) and the inflammatory markers of IL-1β, MCP-1, TNF-α, TLR-4, and IL-6 were also significantly suppressed by rotenone. More importantly, the mitochondrial abnormalities shown by the reduction of SOD2, mitochondrial transcription factor A (TFAM), mitochondrial NADH dehydrogenase subunit 1 (mtND1), and Cytb were significantly restored, indicating that rotenone protected against mitochondrial damage induced by CCl₄ in liver. Moreover, rotenone treatment alone did not significantly alter liver morphology and liver enzymes ALT and AST. CYP2E1, a metabolic enzyme of CCl₄, was also not significantly affected by rotenone. In conclusion, rotenone protected the liver from CCl₄-induced damage possibly by inhibiting the mitochondrial oxidative stress and inflammation.

miR-33a expression sensitizes Lgr5+ HCC-CSCs to doxorubicin via ABCA1

Cancer stem cells (CSCs) are responsible for the unrestrained cell growth and chemo-resistance of malignant tumors. Reports about miR-33a in different type of cancer are limited, and it remains elusive whether there is a link between miR-33a and chemo-resistance of CSCs. Here we report that Lgr5+ hepatocellular carcinoma (HCC) cells from primary tissues and cell lines behave similarly to CSCs and are chemo-resistant to doxorubicin. Significantly, reduced miR-33a expression is associated with the chemo-resistance of Lgr5+ HCC-CSCs, accompanied by an overexpression of ABCA1 which is identified as target of miR-33a by mainly using miRNA luciferase assay and western-blotting. We demonstrate that down-regulation of miR-33a expression directly contributes to chemo-resistance of Lgr5+ HCC-CSCs, and restoring miR-33a expression sensitizes them to doxorubicin via apoptosis by mainly using TUNEL assay, soft agar colony formation assay and xenograft assay. Additionally, reduced miR-33a expression in HCC tissues is associated with chemo-response and poor patient survival, which suggests the therapeutic potential of miR-33a. In conclusion, our work indicates that ectopic miR-33a expression sensitizes Lgr5+ HCC-CSCs to doxorubicin via direct targeting ABCA1, which sheds new light on understanding the mechanism of chemo-resistance in HCC-CSCs and contributes to development of potential therapeutics against HCC.

MicroRNA-214 promotes chronic kidney disease by disrupting mitochondrial oxidative phosphorylation

Mitochondria are critical in determining a cell's energy homeostasis and fate, and mitochondrial dysfunction has been implicated in the pathogenesis of chronic kidney disease (CKD). We sought to identify causative mitochondrial microRNAs. A microarray screen of kidney tissue from healthy mice identified 97 microRNAs that were enriched in the mitochondrial fraction. We focused on microRNA-214-3p (miR-214) because of a very high ratio of mitochondrial to cytoplasmic expression in the kidney compared to other organs. Tubular expression of miR-214 was more abundant in kidney tissue from patients with CKD than from healthy controls, and was positively correlated with the degree of proteinuria and kidney fibrosis. Expression of miR-214 was also increased in the kidney of mouse models of CKD induced by obstruction, ischemia/reperfusion, and albumin overload. Proximal tubule-specific deletion of miR-214 attenuated apoptosis, inflammation, fibrosis, and mitochondrial damage in these CKD models. Pharmacologic inhibition of miR-214 had a similar effect in the albumin overload model of CKD. In vitro, overexpressing miR-214 in proximal tubular cell lines induced apoptosis and disrupted mitochondrial oxidative phosphorylation, while miR-214 expression was upregulated in response to a variety of insults. The mitochondrial genes mt-Nd6 and mt-Nd4l were identified as the specific targets of miR-214 in the kidney. Together, these results demonstrate a pathogenic role of miR-214 in CKD through the disruption of mitochondrial oxidative phosphorylation, and suggest the potential for miR-214 to serve as a therapeutic target and diagnostic biomarker for CKD.

Estrogen-related receptor-α mediates puromycin aminonucleoside-induced mesangial cell apoptosis and inflammatory injury

Glomerular diseases are the leading cause of chronic kidney disease, and mesangial cells (MCs) have been demonstrated to be involved in the pathogenesis. Puromycin aminonucleoside (PAN) is a nephrotoxic drug that induces glomerular injury with elusive mechanisms. The present study was undertaken to investigate the role of PAN in MC apoptosis, as well as the underlying mechanism. Here we found that PAN induced MC apoptosis accompanied by declined cell viability and enhanced inflammatory response. The apoptosis was further evidenced by increments of apoptosis regulator BAX (BAX) and caspase-3 expression. In line with the apoptotic response in MCs following PAN treatment, we also found a remarkable induction of estrogen-related receptor-α (ERRα), an orphan nuclear receptor, at both mRNA and protein levels. Interestingly, ERRα silencing by an siRNA approach resulted in an attenuation of the apoptosis and inflammatory response caused by PAN. More importantly, overexpression of ERRα in MCs significantly triggered MC apoptosis in line with increased BAX and caspase-3 expression. In PAN-treated MCs, ERRα overexpression further aggravated PAN-induced apoptosis. In agreement with the in vitro study, we also observed increased ERRα expression in line with enhanced apoptotic response in renal cortex from PAN-treated rats. These data suggest a detrimental effect of ERRα on PAN-induced MC apoptosis and inflammatory response, which could help us to better understand the pathogenic mechanism of MC injury in PAN nephropathy.

Inhibition of mitochondrial complex I by rotenone protects against acetaminophen-induced liver injury

Acetaminophen (APAP) is widely used as an antipyretic analgesic in clinic. However, overdose-related severe liver injury is a major concern of this drug. Recently, accumulating evidence indicated an important role of mitochondrial abnormality in the pathogenesis of APAP hepatoxicity. Thus, the present investigation was undertaken to evaluate the effect of mitochondrial complex I inhibition by rotenone on APAP hepatoxicity. In this study, male BALB/c mice were pretreated with 250 ppm of rotenone in food for 3 days, then the animals were intraperitoneally injected with 300 mg/kg APAP. After 24 h APAP administration, animals developed severe liver injury as shown by the remarkable elevation of ALT and AST and hepatic centrilobular necrosis in line with the reduced liver GSH content. Strikingly, rotenone treatment markedly attenuated liver injury as shown by the improved liver enzyme release and liver morphology and enhanced liver GSH content. Meanwhile, rotenone ameliorated mitochondrial abnormality, inflammatory response and oxidative stress. Moreover, the downregulation of NOX4, a documented protector against APAP hepatotoxicity, was significantly restored by rotenone. However, mitochondrial complex III inhibitor AZOX failed to protect liver against APAP-induced injury. Together, these results suggested that inhibition of mitochondrial complex I but not mitochondrial complex III played a potent role in protecting against APAP hepatotoxicity.

Celastrol ameliorates cisplatin nephrotoxicity by inhibiting NF-κB and improving mitochondrial function

BACKGROUND

Celastrol is an active ingredient of Chinese medicine Tripterygium wilfordii which is clinically used to treat the immune diseases. Currently, celastrol is documented as a potent agent for treating cancer and inflammatory disorders. This study was to investigate the effect of celastrol on cisplatin nephrotoxicity and the underlying mechanism.

METHODS

Male C57BL/6 mice were treated with cisplatin (20 mg/kg) with or without celastrol treatment (1 and 2 mg/kg/day). In vitro, human proximal tubule epithelial cell line (HK-2) and mouse renal tubule epithelial cells (RTECs) were treated with cisplatin (5 μg/mL) with or without celastrol administration. Then renal injury and cell damage were evaluated.

FINDINGS

In vivo, after celastrol treatment, cisplatin-induced kidney injury was significantly ameliorated as shown by the improvement of renal function (BUN, serum creatinine, and cystatin C), kidney morphology (PAS staining) and oxidative stress (MDA) and the suppression of renal tubular injury markers of KIM-1 and NGAL. Meanwhile, the renal apoptosis and inflammation induced by cisplatin were also strikingly attenuated in celastrol-treated mice. In vitro, celastrol treatment markedly inhibited cisplatin-induced renal tubular cell apoptosis, suppressed NF-κB activation, and improved mitochondrial function evidenced by the restored mtDNA copy number, mitochondrial membrane potential, and OXPHOS activity in cisplatin-treated renal tubular epithelial cells.

INTERPRETATION

This work suggested that celastrol could protect against cisplatin-induced acute kidney injury possibly through suppressing NF-κB and improving mitochondrial function. FUND: The National Natural Science Foundation of China, National Key Research and Development Program, and Natural Science Foundation of Jiangsu Province.

Angiotensin II Stimulates the NLRP3 Inflammasome to Induce Podocyte Injury and Mitochondrial Dysfunction

Background

We previously reported that the NLRP3 inflammasome played an important role in mediating the podocyte injury induced by aldosterone. However, more studies on the role of the NLRP3 inflammasome in the pathogenesis of podocytopathy are still required. The present study was undertaken to study the role of the NLRP3 inflammasome in angiotensin II (Ang II)-induced podocyte injury, as well as the potential mechanisms.

Methods

In this study, we used an Ang II infusion model in NLRP3^-/- mice. In cultured podocytes, we used siRNA to silence NLRP3; then we treated the podocytes with Ang II.

Results

Following Ang II treatment, we found that the NLRP3 inflammasome was significantly activated in line with mitochondrial dysfunction in a dose- and time-dependent manner. Silencing NLRP3 by siRNA transfection ameliorated podocyte apoptosis, attenuated the loss of the podocyte proteins nephrin and podocin, and protected mitochondrial function. Ang II infusion activated the NLRP3 inflammasome, caused albuminuria, and induced podocyte damage, which was all blocked in the NLRP3^-/- mice. At the same time, NLRP3 deletion also ameliorated the mitochondrial dysfunction induced by Ang II infusion. However, the deletion of NLRP3 did not affect the Ang II hypertension.

Conclusion

Taken together, these results demonstrate an important role of the NLRP3 inflammasome in mediating Ang II-induced podocyte injury and mitochondrial dysfunction, suggesting that the NLRP3 inflammasome might be an effective therapeutic target against podocytopathy.

Rotenone ameliorates chronic renal injury caused by acute ischemia/reperfusion

Acute kidney injury (AKI) has been widely recognized as an important risk factor leading to the occurrence and progression of chronic kidney disease (CKD). Thus, development of the strategies in retarding the transition of AKI to CKD is becoming a hot research field. Recently, accumulating evidence suggested a pathogenic role of mitochondrial dysfunction in both AKI and CKD. Therefore, in the present study, we evaluated the effect of mitochondrial complex 1 inhibition by rotenone on the chronic renal damage induced by acute ischemia-reperfusion. The mice were treated with 45 min unilateral renal ischemia and reperfusion (I/R) to induce an acute renal injury. After three days of I/R injury, rotenone at a dose of 200 ppm in food was administered to the mice. Strikingly, after three weeks treatment with rotenone, we found that the unilateral I/R-induced tubular damage, tubulointerstitial fibrosis were all attenuated by rotenone as determined by the tubular injury score, Masson staining, and the levels of collagen-I, collagen-III, fibronectin, PAI-1, and TGF-β. Meanwhile, the enhanced inflammatory markers of TNF-α, IL-1β, IL-6, and IL-18 and apoptotic markers of Bax and caspase-3 were all significantly blunted by inhibiting mitochondrial complex-1. Moreover, rotenone treatment also partially protected the mitochondria as shown by the restoration of mitochondrial SOD (SOD2), ATPB, and mitochondrial DNA copy number. These findings suggested that inhibition of mitochondrial complex-1 activity by rotenone could retard the progression of AKI to CKD probably via protecting the mitochondrial function to some extent.

Role of mitochondrial oxidative stress in modulating the expressions of aquaporins in obstructive kidney disease

Downregulation of aquaporins (AQPs) in obstructive kidney disease has been well demonstrated with elusive mechanisms. Our previous study indicated that mitochondrial dysfunction played a crucial role in this process. However, it is still uncertain how mitochondrial dysfunction affected the AQPs in obstructive kidney disease. This study investigated the role of mitochondria-derived oxidative stress in mediating obstruction-induced downregulation of AQPs. After unilateral ureteral obstruction for 7 days, renal superoxide dismutase 2 (SOD2; mitochondria-specific SOD) was reduced by 85%. Meanwhile, AQP1, AQP2, AQP3, and AQP4 were remarkably downregulated as determined by Western blotting and/or quantitative real-time PCR. Administration of the SOD2 mimic manganese (III) tetrakis(4-benzoic acid)porphyrin chloride (MnTBAP) significantly attenuated AQP2 downregulation in line with complete blockade of thiobarbituric acid-reactive substances elevation, whereas the reduction of AQP1, AQP3, and AQP4 was not affected. The cyclooxygenase (COX)-2/prostaglandin (PG) E2 pathway has been well documented as a contributor of AQP reduction in obstructed kidney; thus, we detected the levels of COX-1/2 and microsomal prostaglandin E synthase 1 (mPGES-1) in kidney and PGE2 secretion in urine. Significantly, MnTBAP partially suppressed the elevation of COX-2, mPGES-1, and PGE2. Moreover, a marked decrease of V2 receptor was significantly restored after MnTBAP treatment. However, the fibrotic response and renal tubular damage were unaffected by MnTBAP in obstructed kidneys. Collectively, these findings suggested an important role of mitochondrial oxidative stress in mediating AQP2 downregulation in obstructed kidney, possibly via modulating the COX-2/mPGES-1/PGE2/V2 receptor pathway.

COX-2 contributes to LPS-induced Stat3 activation and IL-6 production in microglial cells

Many stimuli including lipopolysaccharide (LPS) could activate microglial cells to subsequently cause inflammatory nerve injury. However, the mechanism of LPS-induced neuroinflammation in microglial cells is still elusive. Thus, the present study was undertaken to examine the role of COX-2 in mediating the activation of Stat3 and the production of IL-6 in BV2 cells challenged with LPS. After 24 h treatment, LPS dose-dependently enhanced COX-2 expression at both mRNA and protein levels. Meanwhile, IL-6 with other inflammatory cytokines including IL-1β, TNF-α, and MCP-1 were similarly enhanced by LPS. Then a specific COX-2 inhibitor (NS-398) was administered to BV2 before LPS treatment. Significantly, COX-2 inhibition suppressed the upregulation of IL-6 at both mRNA and protein levels in line with the trend blockade on IL-1β, TNF-α, and MCP-1. Stat3 drives proinflammatory signaling pathways and contributes to IL-6 production via a transcriptional mechanism in many diseases. Here we found that inhibition of COX-2 entirely blocked LPS-induced Stat3 phosphorylation, which might contribute to the blockade of IL-6 production to some extent. Meanwhile, COX-2 siRNA approach largely reproduced the phenotypes shown by specific COX-2 inhibitor in LPS-treated BV2 cells. Together, these findings suggested that COX-2 might contribute to LPS-induced IL-6 production possibly through activating Stat3 signaling pathway in microglial cells.

Renal tubular epithelium-targeted peroxisome proliferator-activated receptor-γ maintains the epithelial phenotype and antagonizes renal fibrogenesis

Accumulating evidence suggests that loss of the renal tubular epithelial phenotype plays an important role in the pathogenesis of renal tubulointerstitial fibrosis. Systemic activation of peroxisome proliferator-activated receptor γ (PPAR-γ) has been shown to be protective against renal fibrosis, although the mechanisms are poorly understood. The present study aimed to define the role of renal tubular epithelium-targeted PPAR-γ in protection of the epithelial phenotype and the antagonism of renal fibrosis and to define the underlying mechanisms. In response to TGF-β1 challenge, PPAR-γ expression and activity in the renal proximal tubule epithelial cells (RPTECs) were significantly reduced, and the reduction was accompanied by decreased E-cadherin and elevated α-SMA, indicating a loss of the epithelial phenotype. Oxidative stress induced by TGF-β1 was shown to be attributed to the alteration of the epithelial phenotype and PPAR-γ inhibition. Activation of PPAR-γ by its agonists of rosiglitazone and 15d-PGJ2 or genetic overexpression of PPAR-γ prevented the loss of the epithelial phenotype induced by TGF-β1 in line with the inhibition of oxidative stress. To explore the role of PPAR-γ in renal tubular epithelial in antagonizing fibrogenesis, PPAR-γ was specifically deleted from RPTECs in mice. Following unilateral ureteral obstruction, the fibrosis was markedly deteriorated in mice with PPAR-γ invalidation in RPTECs. Treatment with rosiglitazone attenuated tubulointerstitial fibrosis and epithelial phenotype transition in WT but not proximal tubule PPAR-γ KO mice. Taken together, these findings identified an important role of renal tubular epithelium-targeted PPAR-γ in maintaining the normal epithelial phenotype and opposing fibrogenesis, possibly via antagonizing oxidative stress.

COX-2/mPGES-1/PGE2 cascade activation mediates uric acid-induced mesangial cell proliferation

Hyperuricemia is not only the main feature of gout but also a cause of gout-related organ injuries including glomerular hypertrophy and sclerosis. Uric acid (UA) has been proven to directly cause mesangial cell (MC) proliferation with elusive mechanisms. The present study was undertaken to examined the role of inflammatory cascade of COX-2/mPGES-1/PGE2 in UA-induced MC proliferation. In the dose- and time-dependent experiments, UA increased cell proliferation shown by the increased total cell number, DNA synthesis rate, and the number of cells in S and G2 phases in parallel with the upregulation of cyclin A2 and cyclin D1. Interestingly, UA-induced cell proliferation was accompanied with the upregulation of COX-2 and mPGES-1 at both mRNA and protein levels. Strikingly, inhibition of COX-2 via a specific COX-2 inhibitor NS-398 markedly blocked UA-induced MC proliferation. Meanwhile, UA-induced PGE2 production was almost entirely abolished. Furthermore, inhibiting mPGES-1 by a siRNA approach in MCs also ameliorated UA-induced MC proliferation in line with a significant blockade of PGE2 secretion. More importantly, in gout patients, we observed a significant elevation of urinary PGE2 excretion compared with healthy controls, indicating a translational potential of this study to the clinic. In conclusion, our findings indicated that COX-2/mPGES-1/PGE2 cascade activation mediated UA-induced MC proliferation. This study offered new insights into the understanding and the intervention of UA-related glomerular injury.

Dihydroartemisinin inhibits indoxyl sulfate (IS)-promoted cell cycle progression in mesangial cells by targeting COX-2/mPGES-1/PGE2 cascade

Dihydroartemisinin (DHA) is a semisynthetic derivative of artemisinin and has been used as an antimalarial drug. Recently, roles of artemisinin and its derivatives in treating diseases besides antimalarial effect were documented. Thus, this study was undertaken to investigate the role of DHA in indoxyl sulfate (IS)-promoted cell cycle progression in glomerular mesangial cells, as well as the potential mechanisms. Under the basal condition, DHA significantly retarded the cell cycle progression as shown by decreased cell percentage in S phase and increased cell percentage in G1/G0 phases in line with reduced cell cycle proteins cyclin A2 and cyclin D1. Interestingly, DHA also inactivated the COX-2/mPGES-1/PGE₂ cascade which has been shown to play a critical role in promoting the mesangial cell cycle progression by our previous studies. Next, we investigated the role of DHA in IS-triggered cell cycle progression in this mesangial cell line. As expected, DHA treatment significantly retarded IS-induced cell cycle progression and inhibited the activation of COX-2/mPGES-1/PGE₂ cascade induced by IS. In summary, these data indicated that DHA inhibited the cell cycle progression in glomerular mesangial cells under normal condition or IS challenge possibly through the inhibition of COX-2/mPGES-1/PGE₂ cascade, suggesting a potential of DHA in treating glomerular diseases with mesangial cell proliferation.

MicroRNA-709 Mediates Acute Tubular Injury through Effects on Mitochondrial Function

Mitochondrial dysfunction has important roles in the pathogenesis of AKI, yet therapeutic approaches to improve mitochondrial function remain limited. In this study, we investigated the pathogenic role of microRNA-709 (miR-709) in mediating mitochondrial impairment and tubular cell death in AKI. In a cisplatin-induced AKI mouse model and in biopsy samples of human AKI kidney tissue, miR-709 was significantly upregulated in the proximal tubular cells (PTCs). The expression of miR-709 in the renal PTCs of patients with AKI correlated with the severity of kidney injury. In cultured mouse PTCs, overexpression of miR-709 markedly induced mitochondrial dysfunction and cell apoptosis, and inhibition of miR-709 ameliorated cisplatin-induced mitochondrial dysfunction and cell injury. Further analyses showed that mitochondrial transcriptional factor A (TFAM) is a target gene of miR-709, and genetic restoration of TFAM attenuated mitochondrial dysfunction and cell injury induced by cisplatin or miR-709 overexpression in vitro Moreover, antagonizing miR-709 with an miR-709 antagomir dramatically attenuated cisplatin-induced kidney injury and mitochondrial dysfunction in mice. Collectively, our results suggest that miR-709 has an important role in mediating cisplatin-induced AKI via negative regulation of TFAM and subsequent mitochondrial dysfunction. These findings reveal a pathogenic role of miR-709 in acute tubular injury and suggest a novel target for the treatment of AKI.

Mitochondrial oxidative stress activates COX-2/mPGES-1/PGE2 cascade induced by albumin in renal proximal tubular cells

COX-2/mPGES-1/PGE2 cascade is of importance in the pathogenesis of kidney injury. Meanwhile, recent studies documented a detrimental role of mitochondrial oxidative stress in kidney diseases. The present study was undertaken to investigate the role of mitochondrial oxidative stress in albumin-induced activation of COX-2/mPGES-1/PGE2 cascade in renal proximal tubular cells. Following albumin overload in mice, we observed a significant increase of oxidative stress and mitochondrial abnormality determined by transmission electron microscope, which was attenuated by the administration of MnTBAP, a mitochondrial SOD2 mimic. More interestingly, albumin overload-induced upregulation of COX-2 and mPGES-1 at mRNA and protein levels was largely abolished by MnTBAP treatment in mice. Meanwhile, urinary PGE2 excretion was also blocked by MnTBAP treatment. Furthermore, mouse proximal tubule epithelial cells (mPTCs) were treated with albumin. Similarly, COX-2/mPGES-1/PGE2 cascade was significantly activated by albumin in dose- and time-dependent manners, which was abolished by MnTBAP treatment in parallel with a blockade of oxidative stress. Collectively, the findings from current study demonstrated that mitochondrial oxidative stress could activate COX-2/mPGES-1/PGE2 cascade in proximal tubular cells under the proteinuria condition. Mitochondrial oxidative stress/COX-2/mPGES-1/PGE2 could serve as the important targets for the treatment of proteinuria-associated kidney injury.

Selective CD28 Blockade Results in Superior Inhibition of Donor-Specific T Follicular Helper Cell and Antibody Responses Relative to CTLA4-Ig

Donor-specific antibodies (DSAs) are a barrier to improved long-term outcomes after kidney transplantation. Costimulation blockade with CTLA4-Ig has shown promise as a potential therapeutic strategy to control DSAs. T follicular helper (Tfh) cells, a subset of CD4⁺ T cells required for optimal antibody production, are reliant on the CD28 costimulatory pathway. We have previously shown that selective CD28 blockade leads to superior allograft survival through improved control of CD8⁺ T cells relative to CTLA4-Ig, but the impact of CD28-specific blockade on CD4⁺ Tfh cells is unknown. Thus, we identified and characterized donor-reactive Tfh cells in a murine skin transplant model and then used this model to evaluate the impact of selective CD28 blockade with an anti-CD28 domain antibody (dAb) on the donor-specific Tfh cell-mediated immune response. We observed that the anti-CD28 dAb led to superior inhibition of donor-reactive CXCR5⁺ PD-1^high Tfh cells, CD95⁺ GL7⁺ germinal center B cells and DSA formation compared with CTLA4-Ig. Interestingly, donor-reactive Tfh cells differentially upregulated CTLA4 expression, suggesting an important role for CTLA4 in mediating the superior inhibition observed with the anti-CD28 dAb. Therefore, selective CD28 blockade as a novel approach to control Tfh cell responses and prevent DSA after kidney transplantation warrants further study.

MnTBAP therapy attenuates the downregulation of sodium transporters in obstructive kidney disease

Ureteral obstruction is associated with reduced expressions of renal sodium transporters, which contributes to impaired urinary concentrating capacity. In this study, we employed a synthetic mitochondrial superoxide dismutase 2 (SOD2) mimic MnTBAP to investigate the role of mitochondrial oxidative stress in modulating the sodium transporters in obstructive kidney disease. Following unilateral ureteral obstruction (UUO) for 7 days, a global reduction of sodium transporters including NHE3, NCC, NKCC2, and ENaCα was observed as determined by qRT-PCR, Western Blotting or immunohistochemistry. Among these sodium transporters, the downregulation of NHE3, NCC, and NKCC2 was partially reversed by MnTBAP treatment. In contrast, the reduction of ENaCα was not affected by MnTBAP. The β and γ subunits of ENaC were not significantly altered by ureteral obstruction or MnTBAP therapy. To further confirm the anti-oxidant effect of MnTBAP, we examined the levels of TBARs in the urine collected from the obstructed ureters of UUO mice and bladder of sham mice. As expected, the increment of urinary TBARs in UUO mice was entirely abolished by MnTBAP therapy, indicating an amelioration of oxidative stress. Meantime, we found that three types of SOD were all reduced in obstructed kidneys determined by qRT-PCR, which was unaffected by MnTBAP. Collectively, these results demonstrated an important role of mitochondrial oxidative stress in mediating the downregulation of sodium transporters in obstructive kidney disease.

Prevalence of honeybee viruses in different regions of China and Argentina

Honeybees are threatened by various pathogens and parasites. More than 18 viruses have been described in honeybees and many of them have been detected in China and Argentina. In China, both Apis cerana and Apis mellifera are raised. In Argentina, beekeepers raise different ecotypes of A. mellifera: European honeybees (in both temperate and subtropical regions) and Africanised honeybees (in subtropical areas only). A thorough study was carried out in both China and Argentina to analyse the current virus presence and distribution in different climatic zones and gather information on different bee species/subspecies. Adult honeybees were collected from apiaries in temperate and subtropical regions of China (including areas with exclusive populations of A. mellifera, areas where A. mellifera and A. cerana co-exist, and areas with exclusive populations of A. cerana) and Argentina. Six viruses, namely, deformed wing virus (DWV), black queen cell virus (BQCV), sacbrood virus (SBV), chronic bee paralysis virus (CBPV), acute bee paralysis virus (ABPV) and Israeli acute paralysis virus (IAPV) were detected in China, both in A. cerana and in A. mellifera, while four viruses (DWV, BQCV, CBPV and ABPV) were present in Argentina. Interestingly, multiple infections were commonly found in China, with up to five different viruses co-circulating in some colonies without apparent abnormalities. In this study, no Chinese samples were positive for slow bee paralysis virus. The most prevalent viruses were BQCV (China) and DWV (Argentina). Kashmir bee virus was absent from samples analysed for both countries.

Polyketides with different post-modifications from desert endophytic fungus Paraphoma sp

Three new polyketides 4,6,8-trihydroxy-5-methyl-3,4-dihydronaphthalen-1(2H)-one (1), 5,7-dihydroxy-3-(1-hydroxyethyl)-3,4-dimethylisobenzofuran-1(3H)-one (2) and 1-(4-hydroxy-6-methoxy-1,7-dimethyl-3-oxo-1,3-dihydroisobenzofuran-1-yl) ethyl acetate (3) together with seven known analogues (4-10) were isolated from desert endophytic fungus Paraphoma sp. The structures of these compounds were elucidated by analysis of NMR data. The absolute configuration of (1-3) was established on the basis of CD experiments. The possible biosynthetic pathway of compounds (1-10) was suggested, which implied that these secondary metabolites might be originated from polyketide biosynthesis with different post-modification reactions. Compounds 2, and 5-8 were evaluated for bioactivities against plant pathogen A. solani, whereas none of them displayed any biological effects. In addition, compounds 1, 2 and 5-10 were also tested for cytotoxic activities against three human cancer cell lines (HepG2 cells, MCF-7 cells and Hela cells) without biological effects.

mPGES-1-Derived PGE2 Contributes to Indoxyl Sulfate-Induced Mesangial Cell Proliferation

BACKGROUND/AIMS

We previously reported that indoxyl sulfate (IS) could cause mesangial cell (MC) proliferation via a cyclooxygenase (COX)-2-dependent mechanism. However, the specific prostaglandin contributing to COX-2 effect on IS-induced MC proliferation remained unknown. Thus, the present study was undertaken to examine the role of microsomal prostaglandin E synthase-1 (mPGES-1)-derived Prostaglandin E2 (PGE2) in IS-induced MC proliferation.

METHODS

IS was administered to the MCs with or without mPGES-1 siRNA pretreatment to induce the MC proliferation which was determined by cell cycle analysis, DNA synthesis, and the expressions of cyclins. In another experimental setting, PGE2 was applied to the MCs to examine its direct effect on MC proliferation, as well as the regulation of prostaglandin E receptors (EPs) by qRT-PCR.

RESULTS

With the administration of IS, mPGES-1(not mPGES-2 and cytosolic PGES) was significantly upregulated at both protein and mRNA levels in line with a promoted MC proliferation. Interestingly, silencing mPGES-1 reduced cell number in S and G2 phases and blocked the upregulation of cyclin A2 and cyclin D1 in parallel with blunted PGE2 release after IS treatment, indicating that mPGES-1-derived PGE2 could contribute to MC proliferation. Furthermore, we confirmed that exogenous PGE2 could directly trigger the proliferative response in MCs. Lastly, we observed a selective upregulation of EP2 after PGE2 treatment and enhanced phosphorylation of NF-κB following IS administration in MCs, suggesting the potential involvements of EP2 and NF-κB in this pathological process.

CONCLUSION

mPGES-1-derived PGE2 contributed to IS-induced mesangial cell proliferation.

Extreme polyandry aids the establishment of invasive populations of a social insect

Although monandry is believed to have facilitated the evolution of eusociality, many highly eusocial insects have since evolved extreme polyandry. The transition to extreme polyandry was likely driven by the benefits of within-colony genetic variance to task specialization and/or disease resistance, but the extent to which it confers secondary benefits, once evolved, is unclear. Here we investigate the consequences of extreme polyandry on the invasive potential of the Asian honey bee, Apis cerana. In honey bees and other Hymenoptera, small newly founded invasive populations must overcome the genetic constraint of their sex determination system that requires heterozygosity at a sex-determining locus to produce viable females. We find A. cerana queens in an invasive population mate with an average of 27 males (range 16-42) that would result in the founding queen/s carrying 75% of their source population's sex alleles in stored sperm. This mating frequency is similar to native-range Chinese A. cerana (mean 29 males, range 19-46). Simulations reveal that extreme polyandry reduces the risk, relative to monandry or moderate polyandry, that colonies produce a high incidence of inviable brood in populations that have experienced a founder event, that is, when sex allele diversity is low and/or allele frequencies are unequal. Thus, extreme polyandry aids the invasiveness of A. cerana in two ways: (1) by increasing the sex locus allelic richness carried to new populations with each founder, thereby increasing sex locus heterozygosity; and (2) by reducing the population variance in colony fitness following a founder event.

Activation of COX-2/mPGES-1/PGE2 Cascade via NLRP3 Inflammasome Contributes to Albumin-Induced Proximal Tubule Cell Injury

BACKGROUND/AIMS

The activation of NOD-like receptor family, pyrin domain containing3 (NLRP3) inflammasome has been shown to be positively correlated with the severity of proteinuria in chronic kidney disease (CKD) patients. Prostaglandin E2 (PGE2), an important inflammatory mediator, is also involved in various kidney injuries. The aim of the present study was to investigate the involvement of NLRP3 inflammasome and PGE2 synthetic pathway in albumin-induced renal tubular injury.

METHODS

Murine proximal tubular cells (mPTCs) were treated with albumin to induce cell injury. NLRP3 siRNA and specific COX-2 inhibitor NS398 were used to define their roles in mediating albumin-induced mPTC injury or the activation of COX-2/mPGES-1/PGE2 cascade.

RESULTS

In mPCTs, inhibition of NLRP3 by a small interfering RNA (siRNA) blocked albumin-induced kidney injury molecule 1 (KIM-1) upregulation, inflammatory response, and cell apoptosis. Albumin markedly activated cyclooxygenase-2 (COX-2)/ microsomal prostaglandin E synthase-1 (mPGES-1)/PGE2 pathway in this cell line, an effect largely abolished by NLRP3 silencing at both mRNA and protein levels. More interestingly, blockade of COX-2 using a specific COX-2 inhibitor NS398 markedly inhibited the upregulation of KIM-1 and inflammatory cytokines, and attenuated cell apoptosis in line with blunted PGE2 release following albumin treatment.

CONCLUSIONS

The findings suggest that COX-2/mPGES-1/PGE2 axis could be activated by albumin in the proximal tubular cells via a NLRP3 inflammasome-mediated mechanism and could thus contribute to proteinuria-related renal tubular cell injury.

PEA3 protects against gentamicin nephrotoxicity: role of mitochondrial dysfunction

Toxin-induced nephrotoxicity is one of the major causes leading to the acute kidney injury (AKI). Among these nephrotoxic toxins, gentamicin can induce AKI with elusive mechanisms. Emerging evidence demonstrated that PEA3 (polyomavirus enhancer activator 3) contributed to the nephrogenesis, while its role in AKI remains unknown. Thus, this study was to investigate the role of PEA3 in gentamicin nephrotoxicity, as well as the underlying mechanisms. In rats, gentamicin treatment (200 mg/kg twice per day) for two days induced remarkable kidney injury with a peak damage on day 5 evaluated by the tubular injury score, proteinuria, and tubular injury markers of NGAL and KIM-1. In parallel with the tubular injury, PEA3 protein and mRNA expressions were significantly upregulated by gentamicin and peaked on day 5. To define the role of PEA3 in gentamicin nephrotoxicity, proximal tubule cells were transfected with PEA3 plasmid with or without gentamicin treatment (1 mg/ml). Notably, overexpression of PEA3 attenuated gentamicin-induced cell injury shown by the ameliorated cell apoptosis and NGAL and KIM-1 upregulation. Meantime, gentamicin caused severe mitochondrial dysfunction, which was largely normalized by PEA3 overexpression. In contrast, silencing PEA3 by a siRNA strategy further deteriorated gentamicin-induced cell apoptosis and mitochondrial dysfunction. In sum, PEA3 protected against gentamicin nephrotoxicity possibly via a mitochondrial mechanism.

Inhibition of COX-2/PGE2 cascade ameliorates cisplatin-induced mesangial cell apoptosis

Cisplatin is one of the most potent cytotoxic drug for the treatment of many types of cancer. However, the side effects on normal tissues, particularly on the kidney, greatly limited its use in clinic. Emerging evidence demonstrated that cisplatin could directly cause mesangial cell apoptosis, while the potential mechanism is still elusive. Here we examined the contribution of COX-2 in cisplatin-induced mesangial cell apoptosis. Firstly, we found cisplatin induced cell apoptosis in mesangial cells shown by increased number of apoptotic cells in parallel with the upregulation of Bax and the downregulation of Bcl-2. Interestingly, cisplatin-induced cell apoptosis was accompanied by an upregulation of COX-2 at both mRNA and protein levels in dose- and time-dependent manners. Importantly, inhibition of COX-2 via a specific COX-2 inhibitor celecoxib markedly blocked cisplatin-induced mesangial cell apoptosis as evidenced by the decreased number of apoptotic cells, blocked increments of cleaved caspase-3 and Bax, and reversed Bcl-2 downregulation. Meanwhile, cisplatin-induced PGE2 production was markedly blocked by the treatment of celecoxib. In conclusion, this study indicated that COX-2/PGE2 cascade activation mediated cisplatin-induced mesangial cell apoptosis. The findings not only offered new insights into the understanding of cisplatin nephrotoxicity but also provided the therapeutic potential by targeting COX-2/PGE2 cascade in treating cisplatin-induced kidney injury.