Metformin improves relevant disease parameters in an autosomal dominant polycystic kidney disease mouse model.

Autosomal dominant polycystic kidney disease (ADPKD), caused by mutations in the polycystin 1 (PKD1) or polycystin 2 genes, presents with progressive development of kidney cysts and eventual end-stage kidney disease with limited treatment options. Previous work has shown that metformin reduces cyst growth in rapid ADPKD mouse models via inhibition of cystic fibrosis transmembrane conductance regulator-mediated fluid secretion, mammalian target of rapamycin, and cAMP pathways. The present study importantly tested the effectiveness of metformin as a therapy for ADPKD in a more clinically relevant Pkd1RC/RC mouse model, homozygous for the R3277C knockin point mutation in the Pkd1 gene. This mutation causes ADPKD in humans. Pkd1RC/RC male and female mice, which have a slow progression to end-stage kidney disease, received metformin (300 mg/kg/day in drinking water vs. water alone) from 3 to 9 or 12 mo of age. As previously reported, Pkd1RC/RC females had a more severe disease phenotype as compared with males. Metformin treatment reduced the ratio of total kidney weight-to-body weight relative to age-matched and sex-matched untreated controls at both 9 and 12 mo and reduced the cystic index in females at 9 mo. Metformin also increased glomerular filtration rate, lowered systolic blood pressure, improved anemia, and lowered blood urea nitrogen levels relative to controls in both sexes. Moreover, metformin reduced gene expression of key inflammatory markers and both gene and protein expression of kidney injury marker-1 and cyclin-dependent kinase-1 versus untreated controls. Altogether, these findings suggest several beneficial effects of metformin in this highly relevant slowly progressive ADPKD mouse model, which may help inform new ADPKD therapies in patients.NEW & NOTEWORTHY Metformin treatment improved ADPKD disease severity in a relevant, slowly progressive ADPKD mouse model that recapitulates a PKD-associated PKD1 mutation. Relative to controls, metformin reduced kidney weight/body weight, cystic index and BUN levels, while improving GFR, blood pressure and anemia. Metformin also reduced key inflammatory and injury markers, along with cell proliferation markers. These findings suggest several beneficial effects of metformin in this ADPKD mouse model, which may help inform new ADPKD therapies in patients.

Semaporin3A inhibitor ameliorates renal fibrosis through the regulation of JNK signaling.

Renal fibrosis is the common pathological pathway in progressive renal diseases. In the present study, we analyzed the roles of semaphorin 3 A (SEMA3A) on renal fibrosis and the effect of SEMA3A inhibitor (SEMA3A-I) using a unilateral ureteral obstruction (UUO) mouse model. Expression of SEMA3A in the proximal tubulus and neuropilin-1, a recepor of SEMA3A, in fibloblast and tubular cells were increased in UUO kidneys. The expression of myofibroblast marker tenascin-C and fibronection as well as renal fibrosis were increased in UUO kidneys, all of which were ameliorated by SEMA3A-I. In addition, the JNK signaling pathway, known as the target of SEMA3A signaling, was activated in proximal tubular cells and fibroblast cells after UUO surgery, and SEMA3A-I significantly attenuated the activation. In vitro, treatments with SEMA3A as well as transforming growth factor-ß1 (TGF-ß1) in human proximal tubular cells lost epithelial cell characteristics, and SEMA3A-I significantly ameliorated this transformation. The JNK inhibitor SP600125 partially reversed SEMA3A and TGF-ß1-induced cell transformation, indicating that JNK signaling is involved in SEMA3A-induced renal fibrosis. In addition, treatment with SEMA3A in fibroblast cells activated expression of tenascin-C, collagen type I, and fibronection, indicating that SEMA3A may accelerate renal fibrosis through the activation of fibroblast cells. Analysis of human data revealed the positive correlation between urinary SEMA3A and urinary N-acetyl-ß-d-glucosaminidase, indicating the association between SEMA3A and tubular injury. In conclusion, SEMA3A signaling is involved in renal fibrosis through the JNK signaling pathway and SEMA3A-I might be a therapeutic option for protecting from renal fibrosis.NEW & NOTEWORTHY Renal fibrosis is the common pathological pathway in the progression of renal diseases. This study, using a unilateral ureteral obstruction (UUO) mouse model, indicated increased semaphorin3A (SEMA3A) signaling in renal tubular cells as well as fibroblast cells under UUO surgery, and SEMA3A inhibitor ameliorated UUO-induced renal fibrosis through the regulation of JNK signaling. The study proposes the potential therapeutic option of SEMA3A inhibitor to treat renal fibrosis.

CRRL269.

RATIONALE: Acute kidney injury (AKI) has a high prevalence and mortality in critically ill patients. It is also a powerful risk factor for heart failure incidence driven by hemodynamic changes and neurohormonal activation. However, no drugs have been approved by the Food and Drug Administration. Endogenous pGC-A (particulate guanylyl cyclase A receptor) activators were reported to preserve renal function and improve mortality in AKI patients, although hypotension accompanied by pGC-A activators have limited their therapeutic potential. OBJECTIVE: We investigated the therapeutic potential of a nonhypotensive pGC-A activator/designer natriuretic peptide, CRRL269, in a short-term, large animal model of ischemia-induced AKI and also investigated the potential of uCNP (urinary C-type natriuretic peptide) as a biomarker for AKI. METHODS AND RESULTS: We first showed that CRRL269 stimulated cGMP generation, suppressed plasma angiotensin II, and reduced cardiac filling pressures without lowering blood pressure in the AKI canine model. We also demonstrated that CRRL269 preserved glomerular filtration rate, increased renal blood flow, and promoted diuresis and natriuresis. Further, CRRL269 reduced kidney injury and apoptosis as evidenced by ex vivo histology and tissue apoptosis analysis. We also showed, compared with native pGC-A activators, that CRRL269 is a more potent inhibitor of apoptosis in renal cells and induced less decreases in intracellular Ca2+ concentration in vascular smooth muscle cells. The renal antiapoptotic effects were at least mediated by cGMP/PKG pathway. Further, CRRL269 inhibited proapoptotic genes expression using a polymerase chain reaction gene array. Additionally, we demonstrated that AKI increased uCNP levels. CONCLUSIONS: Our study supports developing CRRL269 as a novel renocardiac protective agent for AKI treatment.

Alarm interventions for nocturnal enuresis in children.

BACKGROUND: Enuresis (bedwetting) affects up to 20% of five-year-olds and can have considerable social, emotional and psychological effects. Treatments include alarms (activated by urination), behavioural interventions and drugs. OBJECTIVES: To assess the effects of enuresis alarms for treating enuresis in children. SEARCH METHODS: We searched the Cochrane Incontinence Specialised Register, which contains trials identified from the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, MEDLINE In-Process, MEDLINE Epub Ahead of Print, ClinicalTrials.gov, WHO ICTRP, and handsearching of journals and conference proceedings (searched 25 June 2018), and reference lists of relevant articles. SELECTION CRITERIA: We included randomised or quasi-randomised trials of enuresis alarms or alarms combined with another intervention for treating nocturnal enuresis in children between 5 and 16 years old. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed risk of bias and extracted data. MAIN RESULTS: We included 74 trials (5983 children). At treatment completion, alarms may reduce the number of wet nights a week compared to control or no treatment (mean difference (MD) -2.68, 95% confidence interval (CI) -4.59 to -0.78; 4 trials, 127 children; low-quality evidence). Low-quality evidence suggests more children may achieve complete response (14 consecutive dry nights) with alarms compared to control or no treatment (RR 7.23, 95% CI 1.40 to 37.33; 18 trials, 827 children) and that more children may remain dry post-treatment (RR 9.67, 95% CI 4.74 to 19.76; 10 trials, 366 children; low-quality evidence). At treatment completion, we are uncertain whether there is any difference between alarms and placebo drugs in the number of wet nights a week (MD -0.96, 95% CI -2.32 to 0.41; 1 trial, 47 children; very low-quality evidence). Alarms may result in more children achieving complete response than with placebo drugs (RR 1.59, 95% CI 1.16 to 2.17; 2 trials, 181 children; low-quality evidence). No trials comparing alarms to placebo reported the number of children remaining dry post-treatment. Compared with control alarms, code-word alarms probably slightly increase the number of children achieving complete response at treatment completion (RR 1.11, 95% CI 0.97 to 1.27; 1 trial, 353 children; moderate-quality evidence) but there is probably little to no difference in the number of children remaining dry post-treatment (RR 0.91, 95% CI 0.79 to 1.05; moderate-quality evidence). Very low-quality evidence means we are uncertain if there are any differences in effectiveness between the other different types of alarm. At treatment completion, alarms may reduce the number of wet nights a week compared with behavioural interventions (waking, bladder training, dry-bed training, and star chart plus rewards) (MD -0.81, 95% CI -2.01 to 0.38; low-quality evidence) and may increase the number of children achieving complete response (RR 1.77, 95% CI 0.98 to 3.19; low-quality evidence) and may slightly increase the number of children remaining dry post-treatment (RR 1.39, 95% CI 0.81 to 2.41; low-quality evidence). The evidence relating to alarms compared with desmopressin in the number of wet nights a week (MD -0.64, 95% CI -1.77 to 0.49; 4 trials, 285 children) and the number of children achieving complete response at treatment completion (RR 1.12, 95% CI 0.93 to 1.36; 12 trials, 1168 children) is low-quality, spanning possible harms and possible benefits. Alarms probably slightly increase the number of children remaining dry post-treatment compared with desmopressin (RR 1.30, 95% CI 0.92 to 1.84; 5 trials, 565 children; moderate-quality evidence). At treatment completion, we are uncertain if there is any difference between alarms and tricyclics in the number of wet nights a week, the number of children achieving complete response or the number of children remaining dry post-treatment, because the quality of evidence is very low. Due to very low-quality evidence we are uncertain about any differences in effectiveness between alarms and cognitive behavioural therapy, psychotherapy, hypnotherapy and restricted diet. Alarm plus desmopressin may reduce the number of wet nights a week compared with desmopressin monotherapy (MD -0.88, 95% CI -0.38 to -1.38; 2 trials, 156 children; low-quality evidence). Alarm plus desmopressin may increase the number of children achieving complete response (RR 1.32, 95% CI 1.08 to 1.62; 5 trials, 359 children; low-quality evidence) and the number of children remaining dry post-treatment (RR 2.33, 95% CI 1.26 to 4.29; 2 trials, 161 children; low-quality evidence) compared with desmopressin alone. Alarm plus dry-bed training may increase the number of children achieving a complete response compared to dry-bed training alone (RR 3.79, 95% CI 1.85 to 7.77; 1 trial, 80 children; low-quality evidence). It is unclear if there is any difference in the number of children remaining dry post-treatment because of the wide confidence interval (RR 0.56, 95% CI 0.15 to 2.12; low-quality evidence). Due to very low-quality evidence, we are uncertain about any differences in effectiveness between alarm plus bladder training versus bladder training alone. Of the 74 included trials, 17 reported one or more adverse events, nine reported no adverse events and 48 did not mention adverse events. Adverse events attributed to alarms included failure to wake the child, ringing without urination, waking others, causing discomfort, frightening the child and being too difficult to use. Adverse events of comparator interventions included nose bleeds, headaches and abdominal pain. There is probably a slight increase in adverse events between code-word alarm and standard alarm (RR 1.34, 95% CI 0.75 to 2.38; moderate-quality evidence), although we are uncertain because of the wide confidence interval. Alarms probably reduce the number of children experiencing adverse events compared with desmopressin (RR 0.38, 95% CI 0.20 to 0.71; 5 trials, 565 children; moderate-quality evidence). Very low-quality evidence means we cannot be certain whether the adverse event rate for alarms is lower than for other treatments. AUTHORS' CONCLUSIONS: Alarm therapy may be more effective than no treatment in reducing enuresis in children. We are uncertain if alarm therapy is more effective than desmopressin but there is probably a lower risk of adverse events with alarms than with desmopressin. Despite the large number of trials included in this review, further adequately-powered trials with robust randomisation are still needed to determine the full effect of alarm therapy.

Targeting STAT3 signaling in kidney disease.

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway is a multifaceted transduction system that regulates cellular responses to incoming signaling ligands. STAT3 is a central member of the JAK/STAT signaling cascade and has long been recognized for its increased transcriptional activity in cancers and autoimmune disorders but has only recently been in the spotlight for its role in the progression of kidney disease. Although genetic knockout and manipulation studies have demonstrated the salutary benefits of inhibiting STAT3 activity in several kidney disease models, pharmacological inhibition has yet to make it to the clinical forefront. In recent years, significant effort has been aimed at suppressing STAT3 activation for treatment of cancers, which has led to the development of a wide variety of STAT3 inhibitors, but only a handful have been tested in kidney disease models. Here, we review the detrimental role of dysregulated STAT3 activation in a variety of kidney diseases and the current progress in the treatment of kidney diseases with pharmacological inhibition of STAT3 activity.

Phosphoproteomic identification of vasopressin V2 receptor-dependent signaling in the renal collecting duct.

Vasopressin controls water balance largely through PKA-dependent effects to regulate the collecting duct water channel aquaporin-2 (AQP2). Although considerable information has accrued regarding the regulation of water and solute transport in collecting duct cells, information is sparse regarding the signaling connections between PKA and transport responses. Here, we exploited recent advancements in protein mass spectrometry to perform a comprehensive, multiple-replicate analysis of changes in the phosphoproteome of native rat inner medullary collecting duct cells in response to the vasopressin V2 receptor-selective agonist 1-desamino-8D-arginine vasopressin. Of the 10,738 phosphopeptides quantified, only 156 phosphopeptides were significantly increased in abundance, and only 63 phosphopeptides were decreased, indicative of a highly selective response to vasopressin. The list of upregulated phosphosites showed several general characteristics: 1) a preponderance of sites with basic (positively charged) amino acids arginine (R) and lysine (K) in position -2 and -3 relative to the phosphorylated amino acid, consistent with phosphorylation by PKA and/or other basophilic kinases; 2) a greater-than-random likelihood of sites previously demonstrated to be phosphorylated by PKA; 3) a preponderance of sites in membrane proteins, consistent with regulation by membrane association; and 4) a greater-than-random likelihood of sites in proteins with class I COOH-terminal PDZ ligand motifs. The list of downregulated phosphosites showed a preponderance of those with proline in position +1 relative to the phosphorylated amino acid, consistent with either downregulation of proline-directed kinases (e.g., MAPKs or cyclin-dependent kinases) or upregulation of one or more protein phosphatases that selectively dephosphorylate such sites (e.g., protein phosphatase 2A). The phosphoproteomic data were used to create a web resource for the investigation of G protein-coupled receptor signaling and regulation of AQP2-mediated water transport.

BMP1 inhibitor UK383,367 attenuates renal fibrosis and inflammation in CKD.

Renal fibrosis is a key pathological phenomenon of chronic kidney disease (CKD) contributing to the progressive loss of renal function. UK383,367 is a procollagen C proteinase inhibitor that has been selected as a candidate for dermal antiscarring agents, whereas its role in renal fibrosis is unclear. In the present study, UK383,367 was applied to a CKD mouse model of unilateral ureteral obstruction (UUO) and cell lines of renal tubular epithelial cells (mouse proximal tubular cells) and renal fibroblast cells (NRK-49F cells) challenged by transforming growth factor-ß1. In vivo, bone morphogenetic protein 1, the target of UK383,367, was significantly enhanced in UUO mouse kidneys and renal biopsies from patients with CKD. Strikingly, UK383,367 administration ameliorated tubulointerstitial fibrosis as shown by Masson's trichrome staining in line with the blocked expression of collagen type I/III, fibronectin, and α-smooth muscle actin in the kidneys from UUO mice. Similarly, the enhanced inflammatory factors in obstructed kidneys were also blunted. In vitro, UK383,367 pretreatment inhibited the induction of collagen type I/III, fibronectin, and α-smooth muscle actin in both mouse proximal tubular cells and NRK-49F cells treated with transforming growth factor-ß1. Taken together, these findings indicate that the bone morphogenetic protein 1 inhibitor UK383,367 could serve as a potential drug in antagonizing CKD renal fibrosis by acting on the maturation and deposition of collagen and the subsequent profibrotic response and inflammation.

Beta2-adrenergic receptor in kidney biology: A current prospective.

Beta2-adrenergic receptor (ß2 -AR) is a G-protein-coupled adrenergic receptor family member, whose clinical significance has been extensively investigated in lung, cardiovascular and muscular diseases, but its role in kidney biology remains understudied. In this review, we discuss some of the recent studies, where the effect of agonist/antagonist-mediated activation/inhibition of ß2 -AR on disease pathogenesis process was studied, and highlighted the role of ß2 -AR in kidney biology. The expression of ß2 -AR has been noted in many kidney subunits including proximal tubules, glomeruli and podocytes. In vivo studies have shown that in cultured proximal tubules ß2 -AR is involved in Na-ATPase activity and transcellular Na-transport through protein kinase-C activation; whereas in cultured podocytes, it was associated with depolarization of the membrane. The animal studies further revealed that ß2 -AR activation by short-acting ß2 agonists attenuated monocyte activation, pro-inflammatory and pro-fibrotic responses through ß-arrestin2 dependent NF-kB inactivation in diabetic kidney disease; in contrast, activation by long-acting ß2 agonists restored mitochondrial and renal function in the acute kidney injury mice models through PGC-1α dependent mitochondrial biogenesis. In conclusion, the activation of ß2 -AR may present a rapidly developing therapeutic target for renal diseases.

Triptolide prevents extracellular matrix accumulation in experimental diabetic kidney disease by targeting microRNA-137/Notch1 pathway.

MicroRNAs (miRNAs) are involved in multiple biological functions via suppressing target genes. Triptolide is a monomeric compound isolated from a traditional Chinese herb, which exerts protective roles in many kinds of glomerular diseases. However, our understanding of the triptolide effect on miRNAome is still limited. In this study, we found that triptolide significantly decreased albuminuria and improved glomerulosclerosis in rats with diabetic kidney disease (DKD). And triptolide also inhibited extracellular matrix (ECM) protein accumulation and the notch1 pathway activation under diabetic conditions. MiR-137 was significantly decreased in the HG (high glucose)-treated HRMCs and in the kidney tissues of the diabetic rats, but was upregulated by triptolide. In addition, overexpression of miR-137 exerted similar effects to those of triptolide, while miR-137 inhibition aggravated ECM protein accumulation. Luciferase reporter assay results demonstrated that miR-137 directly targets Notch1. Furthermore, the miR-137-dependent effects were due to Notch1 suppression that in turn inhibited ECM protein expression, key mediators of glomerulosclerosis. Finally, downregulation of miR-137 reversed the ECM inhibition role of triptolide in HG cultured HRMCs. Taken together, these findings indicate that triptolide is a potential therapeutic option for DKD and that miR-137/Notch1 pathway play roles in the anti-glomerulosclerosis mechanism of triptolide.

Concomitant use of rapamycin and rosiglitazone delays the progression of polycystic kidney disease in Han:SPRD rats: a study of the mechanism of action.

Attributing to their antiproliferative effect, both rapamycin and peroxisome proliferator-activated receptor-γ (PPARγ) can halt the progression of autosomal dominant polycystic kidney disease (ADPKD). Whether combined use could enhance this effect is unknown. The present study used rapamycin and the PPARγ agonist rosiglitazone concomitantly to observe their combined effects on the proliferation of ADPKD cyst-lining epithelial cells and the progression of ADPKD in Han:SPRD rats. Concomitant use of the two drugs inhibited the proliferation of WT9-12 cells significantly through a superimposition effect. Rosiglitazone inhibited the phosphorylation of mammalian target of rapamycin p70S6K. Concomitant use of rosiglitazone and rapamycin further downregulated the p-p70S6K level. Rosiglitazone also inhibited the phosphorylation of Akt and antagonized the activation of Akt induced by rapamycin. Concomitant use of rosiglitazone and rapamycin significantly retarded the deterioration of renal function, decreased cyst cell proliferation and interstitial fibrosis in Han:SPRD rats. Rapamycin significantly increased cholesterol levels in the blood, whereas rosiglitazone mitigated rapamycin-induced hyperlipidemia. These results indicate that the effects of concomitant use of rosiglitazone and rapamycin in inhibiting the proliferation of WT9-12 cells and delaying the progression of ADPKD in Han:SPRD rats are stronger than those of either drug alone. The present study may provide a new strategy for the long-term treatment of ADPKD.

High-content screening assay-based discovery of paullones as novel podocyte-protective agents.

Podocyte dysfunction and loss is an early event and a hallmark of proteinuric kidney diseases. A podocyte's normal function is maintained via its unique cellular architecture that relies on an intracellular network of filaments, including filamentous actin (F-actin) and microtubules, that provides mechanical support. Damage to this filamentous network leads to changes in cellular morphology and results in podocyte injury, dysfunction, and death. Conversely, stabilization of this network protects podocytes and ameliorates proteinuria. This suggests that stabilization of podocyte architecture via its filamentous network could be a key therapeutic strategy for proteinuric kidney diseases. However, development of podocyte-directed therapeutics, especially those that target the cell's filamentous network, is still lacking, partly because of unavailability of appropriate cellular assays for use in a drug discovery environment. Here, we describe a new high-content screening-based methodology and its implementation on podocytes to identify paullone derivatives as a novel group of podocyte-protective compounds. We find that three compounds, i.e., kenpaullone, 1-azakenpaullone, and alsterpaullone, dose dependently protect podocytes from puromycin aminonucleoside (PAN)-mediated injury in vitro by reducing PAN-induced changes in both the filamentous actin and microtubules, with alsterpaullone providing maximal protection. Mechanistic studies further show that alsterpaullone suppressed PAN-induced activation of signaling downstream of GSK3ß and p38 mitogen-activated protein kinase. In vivo it reduced ADR-induced glomerular injury in a zebrafish model. Together, these results identify paullone derivatives as novel podocyte-protective agents for future therapeutic development.

Salvianolic acid A ameliorates renal ischemia/reperfusion injury by activating Akt/mTOR/4EBP1 signaling pathway.

Salvianolic acid A (Sal A) has been shown to prevent and treat ischemic cardiovascular, as well as cerebral vascular diseases. However, little is known about Sal A in renal ischemia/reperfusion (I/R) injury. In this study, a renal I/R injury model in rats and a hypoxia/reoxygenation (H/R) model to damage proximal renal tubular cells (HK-2) were used to assess whether Sal A halts the development and progression of renal I/R injury. As compared with vehicle treatment, Sal A significantly attenuated kidney injury after renal I/R injury, accompanied by decreases in plasma creatinine, blood urea nitrogen levels, the number of apoptosis-positive tubular cells, and kidney oxidative stress. Sal A also activated phosphorylated protein kinase B (p-Akt) and phosphorylated-mammalian target of rapamycin (p-mTOR) compared with vehicle-treated I/R injury rats. In H/R-injured HK-2 cells, Sal A can reduce the levels of reactive oxygen species in a dose-related manner. Similar to the results from in vivo experiments, in vitro Sal A also increased the protein expression of phosphorylated-eukaryotic initiation factor 4E binding protein 1 (p-4EBP1) compared with vehicle. Furthermore, the cytoprotective activity of Sal A was inhibited by LY294002 and rapamycin. These findings indicate that Sal A can ameliorate renal I/R injury and promote tubular cell survival partly via the Akt/mTOR/4EBP1pathway. Sal A could be a candidate compound to prevent ischemic tissue damage.

Actin dynamics at focal adhesions: a common endpoint and putative therapeutic target for proteinuric kidney diseases.

Proteinuria encompasses diverse causes including both genetic diseases and acquired forms such as diabetic and hypertensive nephropathy. The basis of proteinuria is a disturbance in size selectivity of the glomerular filtration barrier, which largely depends on the podocyte: a terminally differentiated epithelial cell type covering the outer surface of the glomerulus. Compromised podocyte structure is one of the earliest signs of glomerular injury. The phenotype of diverse animal models and podocyte cell culture firmly established the essential role of the actin cytoskeleton in maintaining functional podocyte structure. Podocyte foot processes, actin-based membrane extensions, contain 2 molecularly distinct "hubs" that control actin dynamics: a slit diaphragm and focal adhesions. Although loss of foot processes encompasses disassembly of slit diaphragm multiprotein complexes, as long as cells are attached to the glomerular basement membrane, focal adhesions will be the sites in which stress due to filtration flow is counteracted by forces generated by the actin network in foot processes. Numerous studies within last 20 years have identified actin binding and regulatory proteins as well as integrins as essential components of signaling and actin dynamics at focal adhesions in podocytes, suggesting that some of them may become novel, druggable targets for proteinuric kidney diseases. Here we review evidence supporting the idea that current treatments for chronic kidney diseases beneficially and directly target the podocyte actin cytoskeleton associated with focal adhesions and suggest that therapeutic reagents that target the focal adhesion-regulated actin cytoskeleton in foot processes have potential to modernize treatments for chronic kidney diseases.

Emodin-induced hepatotoxicity was exacerbated by probenecid through inhibiting UGTs and MRP2.

Aggravating effect of probenecid (a traditional anti-gout agent) on emodin-induced hepatotoxicity was evaluated in this study. 33.3% rats died in combination group, while no death was observed in rats treated with emodin alone or probenecid alone, indicating that emodin-induced (150 mg/kg) hepatotoxicity was exacerbated by probenecid (100 mg/kg). In toxicokinetics-toxicodynamics (TK-TD) study, aspartate aminotransferase (AST) and systemic exposure (area under the serum concentration-time curve, AUC) of emodin and its glucuronide were significantly increased in rats after co-administrated with emodin and probenecid for 28 consecutive days. Results showed that the increased AUC (increased by 85.9%) of emodin was mainly caused by the decreased enzyme activity of UDP-glucuronosyltransferases (UGTs, decreased by 11.8%-58.1%). In addition, AUC of emodin glucuronide was increased 5-fold, which was attributed to the decrease of multidrug-resistant-protein 2 (MRP2) protein levels (decreased by 54.4%). Similarly, in vitro experiments proved that probenecid reduced the cell viability of emodin-treated HepG2 cells through inhibiting UGT1A9, UGT2B7 and MRP2. Our findings demonstrated that emodin-induced hepatoxicity was exacerbated by probenecid through inhibition of UGTs and MRP2 in vivo and in vitro, indicating that gout patients should avoid taking emodin-containing preparations in combination with probenecid for a long time.

Aquaporin-2 plays an important role in water transportation through the bladder wall in rats.

AIM: We investigated the role of the bladder wall in permeating water, focusing on aquaporins. METHODS: Female Sprague-Dawley rats weighing 300 g were used to investigate the role of the bladder wall in saline permeation. Changes in intravesical fluid volume and sodium concentration were measured in the desmopressin acetate hydrate-loaded and control groups 3 h after administration. Bladders were resected to measure aquaporin-1, 2, and 3 gene expression using qRT-PCR. Additionally, the change of aquaporin-2 expression was measured using Western blotting and immunohistochemistry in intravesical aquaporin-2 siRNA-treated and control groups. RESULTS: Although the intravesical fluid volume and sodium concentration significantly decreased from 0 to 3 h (1.00 ± 0.00 vs 0.83 ± 0.08 mL, 157.80 ± 1.30 vs 146.8 ± 1.92 mEq/mL, P < 0.01, respectively in the control group), administration of desmopressin did not affect the extent of volume change. Aquaporin-2 expression was significantly higher in the 3-h distended bladders than in the empty bladder. Aquaporin-2 siRNA treatment suppressed aquaporin-2 expression and the change of intravesical fluid volume from 0 to 3 h (1.00 ± 0.00 and 0.99 ± 0.02 mL), which was related to the suppression of sodium concentration change in comparison with control siRNA treatment (149.6 ± 2.4 vs 143.6 ± 3.67 mEq/mL, P < 0.05). CONCLUSIONS: The rat urinary bladder absorbs water and salts under the full-filled condition. Aquaporin-2 plays an important role in the transport of water, accompanied by sodium concentration change. We demonstrated a part of the bladder absorption mechanism, which may lead to development of a new method for regulating bladder storage function.

New insights into the role and mechanism of Wnt/ß-catenin signalling in kidney fibrosis.

Wnt/ß-catenin is an evolutionarily conserved, developmental signalling pathway that regulates embryogenesis, injury repair and pathogenesis of human diseases. Dysregulated activation of Wnt/ß-catenin is associated with the development and progression of renal fibrotic lesions after injury. Wnt are induced and ß-catenin is activated in various models of experimental chronic kidney disease (CKD) and in human nephropathies. Recent findings indicate that pro(renin) receptor is an amplifier of Wnt/ß-catenin by acting as a downstream target and an obligatory component for its signal transduction. Genetic blockade of Wnt secretion in a cell type-specific manner uncovers renal tubular epithelium as the major source of Wnt ligands in CKD. Wnt/ß-catenin controls the expression of a wide variety of downstream mediators implicated in kidney fibrosis, such as fibronectin, Snail1, matrix metalloproteinase-7, hepatocyte growth factor and various components of the renin-angiotensin system. Targeted inhibition of Wnt/ß-catenin is able to ameliorate kidney fibrotic lesions in pre-clinical settings. In this review, we summarize recent advances in our understanding of the regulation, signal transduction, role and mechanisms of Wnt/ß-catenin signalling in the pathogenesis of kidney fibrosis. We also discuss the therapeutic potential of targeting this pathway for the treatment of fibrotic CKD.

Desmopressin 120 mcg, 180 mcg, 240 mcg: The right treatment for the right patient.

BACKGROUND: The first-line drug therapy for patients with nocturnal enuresis (NE) associated with nocturnal polyuria and normal bladder function is desmopressin (dDAVP). OBJECTIVE: To evaluate if increasing dose of oral desmopressin lyophilisate (MELT) can improve response rates to dDAVP and is useful in enuretic children. MATERIALS AND METHODS: We enrolled a total of 260 children all diagnosed with NE. Enuretic children were treated with increasing MELT at a dose of 120, 180 and 240 mcg a day. RESULTS: We included in our study a total of 237 children, 164 males (69.2%) and 73 females (30.8%) aged between 5 and 18 years (mean age 10.32 ± 2.52 years). Of the 237 patients enrolled in the study and treated with MELT 120 mcg, a full response was achieved in 135 (56.9%). A partial response was achieved in 21 (8.9%) patients, therefore the dose was increased up to 180 mcg, with further improving symptoms (14.3%) or full response (9.5%), and up to 240 mcg, without usefulness. CONCLUSIONS: MELT at the dose of 120 mcg resulted efficacy and safety; the increased dose up to 180 mcg resulted poorly efficacy; finally, the further increase up to 240 mcg did not improve the symptoms with the increased risk of side effects.

Molecular modifiers of kidney stones.

PURPOSE OF REVIEW: This review discusses the role of molecular modifiers as inhibitors of kidney stone formation, drawing largely from in-vitro evidence while also citing relevant in-vivo studies. An emphasis is placed on physical observations of crystal growth inhibition, including mechanisms of action that focus predominantly on the literature of calcium oxalate and L-cystine. RECENT FINDINGS: The last decade has witnessed several breakthroughs in the identification of molecules with promise to curb kidney stone formation, as well as discoveries of the mechanisms by which these molecules (or combinations thereof) function as inhibitors of pathological crystal growth. Studies of L-cystine and calcium oxalate crystallization have uncovered inhibitors that are more effective than current therapies. In-vitro assays using advanced techniques such as atomic force microscopy have been able to characterize modifier-crystal interactions and the mechanisms of crystal growth inhibition. A recent study of calcium oxalate crystals uncovered a new inhibition pathway leading to crystal dissolution at relatively low modifier concentrations. SUMMARY: Advanced methods of identifying therapeutics for kidney stone disease have created a greater awareness of the potential impact of crystal modifiers in pathological crystallization. Many natural and synthetic species have the capacity to act as growth inhibitors; however, the challenge of bridging in-vitro and in-vivo evidence has proven to be difficult. Future effort to better integrate laboratory research, clinical trials and animal studies has the potential to broaden our understanding of crystal growth modification and its role in mitigating pathological crystallization.

Switching from immediate- to extended-release cysteamine in nephropathic cystinosis patients: a retrospective real-life single-center study.

BACKGROUND: Nephropathic cystinosis is a rare lysosomal storage disease which is characterized by the accumulation of free cystine in lysosomes and subsequent intracellular crystal formation of cystine throughout the body. If not treated with cysteamine, a cystine-depleting agent, end-stage renal disease will develop early, followed by multiple organ failure as the disease progresses. The established cysteamine formulation requires a strict dosing regimen at 6-h intervals. An extended release (ER) twice-daily formulation has recently been developed. The aim of our study was to evaluate the implementation and outcomes of this option in routine care. METHODS: All pediatric cystinosis patients' records in Hannover Medical School were screened, and data on cysteamine therapy, tolerability, dosing, estimated glomerular filtration rates (eGFR), white blood cell cystine levels, and proton pump inhibitor (PPI) use were extracted for the period January 2014 to January 2016. RESULTS: The median age of the 12 patients enrolled in the study was 12.5 (range 1-18) years. At the end of the study period ten of these patients received ER-cysteamine. There were no additional side effects. Halitosis/bad breath was often subjectively judged as improved or eliminated, and PPI use could be stopped in one of three patients. The main reasons for switching to the ER formulation were difficult night-time administration and uncontrolled disease. Mean eGFR values remained stable with a median of 67 ml/min/1.73 m2 before and after the transition. White blood cell (WBC) cystine values remained low after the switch (1 nmol/mg protein before and after transition; p = 0.64). CONCLUSIONS: In this single-center cohort, the switch from IR- to ER-cysteamine was safe and effective over the short term and provided advantages in terms of frequency of administration and less halitosis/bad breath. The long-term benefit of this option needs to be evaluated in future studies.