Lights on for aminopeptidases in cystic kidney disease

While erudite cell biologists have for many decades described singular immotile appendages known as primary cilia to be present on most cells in our bodies, cilial function(s) long remained an enigma. Driven largely by an ever increasing number of discoveries of genetic defects in primary cilia during the past decade, cilia were catapulted from a long lasting existence in obscurity into the bright spotlight in cell biology and medicine. The study by O’Toole et al. in this issue of the JCI adds a novel “enzymatic” facet to the rapidly growing information about these little cellular tails, by demonstrating that defects in the XPNPEP3 gene, which encodes mitochondrial and cytosolic splice variants of X-prolyl aminopeptidase 3, can cause nephronophthisis-like ciliopathy. Future studies are in order now to elucidate the cystogenic pathways affected by disrupted enzymatic function of XPNPEP3 in cilia-related cystogenic diseases. Based on a flood of recent evidence, primary cilia are now heralded as sensory organelles for detection and transmission of a broad range of cues from the extracellular environment of cells (1), including mechanical and chemical information as diverse as fluid flow in kidneys, mechanical bone deformation, and light and odorant detection (2). By processing such physical and chemical information from the environment into molecular signals in development and postnatal growth and homeostasis, cilia can affect cell differentiation and polarity and cell cycle control (3). Genetic damage to primary cilia results in a spectrum of perplexing disorders with seemingly disparate manifestations, now classified as ciliopathies. A growing list of bona fide ciliopathies at present includes Bardet-Biedl syndrome (BBS), nephronophthisis (NPHP), and Senior-Loken syndrome (SNLS), just to name a few. Common clinical features of ciliopathies include the hallmark renal cysts as well as liver disease, laterality defects, polydactyly, cognitive dysfunction, retinal degeneration, skeletal bone defects, and obesity among others (4). Cilia are composed of a plasma membrane sheath, enveloping a microtubule-based axoneme that extends from the basal body. Cilia dismantle when cells enter cell cycle and reassemble during interphase. Growth and maintenance of cilia depend on microtubule-based transport motors, including kinesin II–dependent anterograde intraflagellar transport (IFT) and dynein-dependent retrograde IFT (Figure ​(Figure1)1) (5). The cargo targeted to cilia by these transport processes includes, among others, components of several major signaling pathways, including sonic hedgehog receptors (6, 7) and WNT receptors (8). Thus, primary cilia modulate activities of major developmental signaling pathways involved in cell cycle control, differentiation, and planar cell polarity, and various ciliopathy-associated problems can be attributed to disrupted hedgehog and WNT signaling (2, 9, 10). Open in a separate windowFigure 1Ciliary and/or mitochondrial dysfunction as consequences of defective ciliary and mitochondrial XPNPEP3.Cilia consist of a microtubule-based axoneme enveloped by a specialized plasma membrane. The basal body is a microtubule-organizing center that anchors the axoneme. The transition zone (composed of transition fibers) filters molecules that enter or exit the cilium at the junction of the basal body. Axonemal and membrane components are transported in raft macromolecular particles (complexes A and B) by intraflagellar transport (IFT) along the axonemal doublet microtubules toward the tip complex, supported by microtubule end binding protein 1 (Eb1). Anterograde IFT toward the cilial tip is driven by heterotrimeric kinesin-2. Retrograde IFT back to the cell body occurs via the cytoplasmic motor protein dynein. As suggested in the study by O’Toole et al. in this issue of the JCI (13), a cytosolic 48-kDa form of XPNPEP3 may mediate enzymatic cleavage of known cystic-disease proteins ALMS1, LRRC50, and CEP290/NPHP6, and/or other yet unknown ciliary proteins, possibly regulating ciliary targeting or transport. O’Toole et al. report that loss of substrate cleavage, which is associated with defective XPNPEP3, leads to ciliary dysfunction. Similarly, loss of mitochondrial 51-kDa XPNPEP3 peptidase activity may result in failure to cleave yet unknown mitochondrial XPNPEP3 substrates and mitochondrial dysfunction. However, it is unclear at this time whether or how mitochondrial XPNPEP3 defects affect ciliary function. Image adapted with permission from Journal of the American Society of Nephrology (9).     

DNA replication stress underlies renal phenotypes in CEP290-associated Joubert syndrome

Juvenile ciliopathy syndromes that are associated with renal cysts and premature renal failure are commonly the result of mutations in the gene encoding centrosomal protein CEP290. In addition to centrosomes and the transition zone at the base of the primary cilium, CEP290 also localizes to the nucleus; however, the nuclear function of CEP290 is unknown. Here, we demonstrate that reduction of cellular CEP290 in primary human and mouse kidney cells as well as in zebrafish embryos leads to enhanced DNA damage signaling and accumulation of DNA breaks ex vivo and in vivo. Compared with those from WT mice, primary kidney cells from Cep290-deficient mice exhibited supernumerary centrioles, decreased replication fork velocity, fork asymmetry, and increased levels of cyclin-dependent kinases (CDKs). Treatment of Cep290-deficient cells with CDK inhibitors rescued DNA damage and centriole number. Moreover, the loss of primary cilia that results from CEP290 dysfunction was rescued in 3D cell culture spheroids of primary murine kidney cells after exposure to CDK inhibitors. Together, our results provide a link between CEP290 and DNA replication stress and suggest CDK inhibition as a potential treatment strategy for a wide range of ciliopathy syndromes.     

Functional Testing for Tranexamic Acid Duration of Action Using Modified Viscoelastometry

IntroductionTranexamic acid (TXA) is the standard medication to prevent or treat hyperfibrinolysis. However, prolonged inhibition of lysis (so-called “fibrinolytic shutdown”) correlates with increased mortality. A new viscoelastometric test enables bedside quantification of the antifibrinolytic activity of TXA using tissue plasminogen activator (TPA).Materials and MethodsTwenty-five cardiac surgery patients were included in this prospective observational study. In vivo, the viscoelastometric TPA test was used to determine lysis time (LT) and maximum lysis (ML) over 96 h after TXA bolus. Additionally, plasma concentrations of TXA and plasminogen activator inhibitor 1 (PAI-1) were measured. Moreover, dose effect curves from the blood of healthy volunteers were performed in vitro. Data are presented as median (25–75th percentile).ResultsIn vivo TXA plasma concentration correlated with LT (r = 0.55; p < 0.0001) and ML (r = 0.62; p < 0.0001) at all time points. Lysis was inhibited up to 96 h (LT_TPA-test: baseline: 398 s [229–421 s] vs. at 96 h: 886 s [626–2,175 s]; p = 0.0013). After 24 h, some patients (n = 8) had normalized lysis, but others (n = 17) had strong lysis inhibition (ML <30%; p < 0.001). The high- and low-lysis groups differed regarding kidney function (cystatin C: 1.64 [1.42–2.02] vs. 1.28 [1.01–1.52] mg/L; p = 0.002) in a post hoc analysis. Of note, TXA plasma concentration after 24 h was significantly higher in patients with impaired renal function (9.70 [2.89–13.45] vs.1.41 [1.30–2.34] µg/mL; p < 0.0001). In vitro, TXA concentrations of 10 µg/mL effectively inhibited fibrinolysis in all blood samples.ConclusionsDetermination of antifibrinolytic activity using the TPA test is feasible, and individual fibrinolytic capacity, e.g., in critically ill patients, can potentially be measured. This is of interest since TXA-induced lysis inhibition varies depending on kidney function.     

Loss of the BMP antagonist USAG-1 ameliorates disease in a mouse model of the progressive hereditary kidney disease Alport syndrome

The glomerular basement membrane (GBM) is a key component of the filtering unit in the kidney. Mutations involving any of the collagen IV genes (COL4A3, COL4A4, and COL4A5) affect GBM assembly and cause Alport syndrome, a progressive hereditary kidney disease with no definitive therapy. Previously, we have demonstrated that the bone morphogenetic protein (BMP) antagonist uterine sensitization–associated gene-1 (USAG-1) negatively regulates the renoprotective action of BMP-7 in a mouse model of tubular injury during acute renal failure. Here, we investigated the role of USAG-1 in renal function in Col4a3^–/– mice, which model Alport syndrome. Ablation of Usag1 in Col4a3^–/– mice led to substantial attenuation of disease progression, normalization of GBM ultrastructure, preservation of renal function, and extension of life span. Immunohistochemical analysis revealed that USAG-1 and BMP-7 colocalized in the macula densa in the distal tubules, lying in direct contact with glomerular mesangial cells. Furthermore, in cultured mesangial cells, BMP-7 attenuated and USAG-1 enhanced the expression of MMP-12, a protease that may contribute to GBM degradation. These data suggest that the pathogenetic role of USAG-1 in Col4a3^–/– mice might involve crosstalk between kidney tubules and the glomerulus and that inhibition of USAG-1 may be a promising therapeutic approach for the treatment of Alport syndrome.     

Long Noncoding RNA Arid2-IR Is a Novel Therapeutic Target for Renal Inflammation

Increasing evidence shows that microRNAs play an important role in kidney disease. However, functions of long noncoding RNAs (lncRNAs) in kidney diseases remain undefined. We have previously shown that TGF-β1 plays a diverse role in renal inflammation and fibrosis and Smad3 is a key mediator in this process. In this study, we used RNA-sequencing to identify lncRNAs related to renal inflammation and fibrosis in obstructive nephropathy induced in Smad3 wild-type and knockout mice. We found that Arid2-IR was a Smad3-associated lncRNA as a Smad3 binding site was found in the promoter region of Arid2-IR and deletion of Smad3 abolished upregulation of Arid2-IR in the diseased kidney. In vitro knockdown of Arid2-IR from tubular epithelial cells produced no effect on TGF-β-induced Smad3 signaling and fibrosis but inhibited interleukin-1β-stimulated NF-κB-dependent inflammatory response. In contrast, overexpression of Arid2-IR promoted interleukin-1β-induced NF-κB signaling and inflammatory cytokine expression without alteration of TGF-β1-induced fibrotic response. Furthermore, treatment of obstructed kidney with Arid2-IR shRNA blunted NF-κB-driven renal inflammation without effect on TGF-β/Smad3-mediated renal fibrosis. Thus, Arid2-IR is a novel lncRNA that functions to promote NF-κB-dependent renal inflammation. Blockade of Arid2-IR may represent a novel and specific therapy for renal inflammatory disease.     

Age-related GSK3β overexpression drives podocyte senescence and glomerular aging

As life expectancy continues to increase, clinicians are challenged by age-related renal impairment that involves podocyte senescence and glomerulosclerosis. There is now compelling evidence that lithium has a potent antiaging activity that ameliorates brain aging and increases longevity in Drosophila and Caenorhabditis elegans. As the major molecular target of lithium action and a multitasking protein kinase recently implicated in a variety of renal diseases, glycogen synthase kinase 3β (GSK3β) is overexpressed and hyperactive with age in glomerular podocytes, correlating with functional and histological signs of kidney aging. Moreover, podocyte-specific ablation of GSK3β substantially attenuated podocyte senescence and glomerular aging in mice. Mechanistically, key mediators of senescence signaling, such as p16^INK4A and p53, contain high numbers of GSK3β consensus motifs, physically interact with GSK3β, and act as its putative substrates. In addition, therapeutic targeting of GSK3β by microdose lithium later in life reduced senescence signaling and delayed kidney aging in mice. Furthermore, in psychiatric patients, lithium carbonate therapy inhibited GSK3β activity and mitigated senescence signaling in urinary exfoliated podocytes and was associated with preservation of kidney function. Thus, GSK3β appears to play a key role in podocyte senescence by modulating senescence signaling and may be an actionable senostatic target to delay kidney aging.     

Polycystic Kidney Disease in the Medaka (Oryzias latipes) pc Mutant Caused by a Mutation in the Gli-Similar3 (glis3) Gene

Polycystic kidney disease (PKD) is a common hereditary disease in humans. Recent studies have shown an increasing number of ciliary genes that are involved in the pathogenesis of PKD. In this study, the Gli-similar3 (glis3) gene was identified as the causal gene of the medaka pc mutant, a model of PKD. In the pc mutant, a transposon was found to be inserted into the fourth intron of the pc/glis3 gene, causing aberrant splicing of the pc/glis3 mRNA and thus a putatively truncated protein with a defective zinc finger domain. pc/glis3 mRNA is expressed in the epithelial cells of the renal tubules and ducts of the pronephros and mesonephros, and also in the pancreas. Antisense oligonucleotide-mediated knockdown of pc/glis3 resulted in cyst formation in the pronephric tubules of medaka fry. Although three other glis family members, glis1a, glis1b and glis2, were found in the medaka genome, none were expressed in the embryonic or larval kidney. In the pc mutant, the urine flow rate in the pronephros was significantly reduced, which was considered to be a direct cause of renal cyst formation. The cilia on the surface of the renal tubular epithelium were significantly shorter in the pc mutant than in wild-type, suggesting that shortened cilia resulted in a decrease in driving force and, in turn, a reduction in urine flow rate. Most importantly, EGFP-tagged pc/glis3 protein localized in primary cilia as well as in the nucleus when expressed in mouse renal epithelial cells, indicating a strong connection between pc/glis3 and ciliary function. Unlike human patients with GLIS3 mutations, the medaka pc mutant shows none of the symptoms of a pancreatic phenotype, such as impaired insulin expression and/or diabetes, suggesting that the pc mutant may be suitable for use as a kidney-specific model for human GLIS3 patients.     

Major Pathways of Polymyxin-Induced Apoptosis in Rat Kidney Proximal Tubular Cells

Identifying the pathways involved in the apoptotic cell death that is associated with polymyxin-induced nephrotoxicity is crucial for the development of strategies to ameliorate this dose-limiting side effect and for the development of novel safer polymyxins. The primary aim of this study was to identify the major pathways which lead to polymyxin-induced apoptosis in cultured rat kidney proximal tubular cells (NRK-52E). Caspase-3, -8, and -9 were activated by polymyxin B treatment in a concentration-dependent manner. Concentration- and time-dependent expression of FasL and deformation of mitochondrial morphology were revealed following polymyxin B treatment. The proportion of cells with filamentous mitochondria (regular morphology) following an 8-h treatment with 1.0 mM polymyxin B was 56.2% ± 9.7% (n = 3). This was decreased to 30.7% ± 7.5% when the polymyxin B concentration was increased to 2.0 mM. The mitochondrial membrane potential (Δψ_m) decreased to 14.1% ± 2.9% in the cells treated with 1.0 mM polymyxin B for 24 h (n = 3) compared to that in the untreated control group. Concomitantly, concentration- and time-dependent production of mitochondrial superoxide was also observed. This study is the first to have demonstrated that polymyxin-induced apoptosis is mediated through both the death receptor and mitochondrial pathways in cultured renal tubular cells. It provides key information not only for the amelioration of polymyxin-induced nephrotoxicity but also for the discovery of novel safer polymyxin-like antibiotics against Gram-negative “superbugs.”     

Correction: Culturing and patch clamping of Jurkat T cells and neurons on Al2O3 coated nanowire arrays of altered morphology

Correction for ‘Culturing and patch clamping of Jurkat T cells and neurons on Al₂O₃ coated nanowire arrays of altered morphology’ by Jann Harberts et al., RSC Adv., 2019, 9, 11194–11201.

The authors regret that some of the figure citations in the text were incorrect in the original article. The correct figure citations are as follows. On page 11197 the sentence beginning, “For neurons…” should read, “For neurons, shown in Fig. 2d, we observed cell viabilities of 73.9 ± 3.6% and 72.9 ± 6.2% on the control substrates and 65.4 ± 4.5% and 66.5 ± 4.4% on the NW substrates.” Additionally, the sentence beginning, “Furthermore, exemplary images…” should read, “Furthermore, exemplary images of stained neurons cultured on both types of NWs are shown in Fig. 2e and f as well as on the control substrates in Fig. S2.”The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Sirt1 activation protects the mouse renal medulla from oxidative injury

Sirtuin 1 (Sirt1) is a NAD⁺-dependent deacetylase that exerts many of the pleiotropic effects of oxidative metabolism. Due to local hypoxia and hypertonicity, the renal medulla is subject to extreme oxidative stress. Here, we set out to investigate the role of Sirt1 in the kidney. Our initial analysis indicated that it was abundantly expressed in mouse renal medullary interstitial cells in vivo. Knocking down Sirt1 expression in primary mouse renal medullary interstitial cells substantially reduced cellular resistance to oxidative stress, while pharmacologic Sirt1 activation using either resveratrol or SRT2183 improved cell survival in response to oxidative stress. The unilateral ureteral obstruction (UUO) model of kidney injury induced markedly more renal apoptosis and fibrosis in Sirt1^+/– mice than in wild-type controls, while pharmacologic Sirt1 activation substantially attenuated apoptosis and fibrosis in wild-type mice. Moreover, Sirt1 deficiency attenuated oxidative stress–induced COX2 expression in cultured mouse renal medullary interstitial cells, and Sirt1^+/– mice displayed reduced UUO-induced COX2 expression in vivo. Conversely, Sirt1 activation increased renal medullary interstitial cell COX2 expression both in vitro and in vivo. Furthermore, exogenous PGE₂ markedly reduced apoptosis in Sirt1-deficient renal medullary interstitial cells following oxidative stress. Taken together, these results identify Sirt1 as an important protective factor for mouse renal medullary interstitial cells following oxidative stress and suggest that the protective function of Sirt1 is partly attributable to its regulation of COX2 induction. We therefore suggest that Sirt1 provides a potential therapeutic target to minimize renal medullary cell damage following oxidative stress.     

Controlled Rewarming after Hypothermia: Adding a New Principle to Renal Preservation

Early graft dysfunction due to preservation/reperfusion injury still represents a notable issue after kidney transplantation, affecting long term prognosis of graft viability. One trigger of postischemic cell dysfunction could be recognized in the abrupt temperature shift from hypo‐ to normothermia, leading to mitochondrial dysfunction and proapoptotic signal transduction.Here we propose a technique to cope with this “rewarming injury” by interposing a period of gentle warming up by hypo‐ to subnormothermic machine perfusion of the isolated graft prior to warm reperfusion. Porcine kidneys were subjected either to 18 hours of hypothermic machine preservation (HMP) or 18 hours static cold storage + 3 hours of gentle, machine controlled oxygenated rewarming (COR). Functional integrity was evaluated in both groups by subsequent normothermic reperfusion in vitro.The functional benefit of COR was documented by an approximately twofold increase in renal clearances of creatinine as well as urea upon warm reperfusion, compared to controls. This was accompanied with a notable mitigation of postischemic mitochondrial dys‐homeostasis. COR significantly improved renal oxygen consumption and maintained total NAD tissue content upon reperfusion. Mitochondrial initiation of cellular apoptosis, as evidenced by activation of caspase 9 was also largely prevented after COR but not in controls.The concept of gentle regenerative graft rewarming could become a valuable adjunct in renal transplantation.     

Cefepime neurotoxicity in the intensive care unit: a cause of severe,underappreciated encephalopathy

Introduction

Cefepime, a broad spectrum antibiotic, is commonly prescribed in intensive care units (ICU) and may be an overlooked cause of neurologic symptoms such as encephalopathy, myoclonus, seizures, and coma. We aimed to characterize cefepime neurotoxicity in the ICU.

Methods

We performed a retrospective study of adult ICU patients treated with intravenous cefepime for at least 3 days between January 1, 2009 and December 31, 2011. The primary outcome was the development of cefepime neurotoxicity, with the likelihood of causality ascribed via a modified Delphi method.

Results

This study included 100 patients. The mean age was 65.8 years (± 12.7 years). The median daily average dose of cefepime was 2.5 (IQR 2.0 to 3.5) grams. The median treatment duration was 6 (IQR 4 to 10) days. Renal failure in any form was present in 84 patients. Chronic kidney disease affected 40 patients, and 77 had acute kidney injury. Cefepime neurotoxicity occurred in 15 patients. Of these, seven were considered definite cases, three probable, and five possible. Neurotoxic symptoms included impaired consciousness (n = 13), myoclonus (n = 11), disorientation (n = 6), and nonconvulsive status epilepticus (n = 1). The dose of cefepime was appropriately adjusted for renal clearance in 64 patients (75.3%) without cefepime neurotoxicity and four patients (28.6%) with neurotoxicity (P = 0.001). Chronic kidney disease was present in 30 patients (35.3%) without neurotoxicity and in 10 (66.7%) of those with neurotoxicity (P = 0.04).

Conclusions

Critically ill patients with chronic kidney disease are particularly susceptible to cefepime neurotoxicity. Myoclonus and impaired consciousness are the predominant clinical manifestations. Neurotoxic symptoms occur more often when the cefepime dose is not adjusted for renal function, but can still occur despite those modifications.     

A novel WT1 gene mutation in a chinese girl with denys‐drash syndrome

ObjectiveDenys‐Drash syndrome (DDS) is defined by the triad of Wilms tumor, nephrotic syndrome, and/or ambiguous genitalia. Genetic testing may help identify new gene mutation sites and play an important role in clinical decision‐making.MethodsWe present a patient with an XY karyotype and female appearance, nephropathy, and Wilms tumor in the right kidney. Genomic DNA was extracted from peripheral blood cells according to standard protocols. “Next‐generation” sequencing (NGS) was performed to identify novel variants. The variant was analyzed with Mutation Taster, and its function was explored by a cell growth inhibition assay.ResultsWe found the first case of Denys‐Drash syndrome with the uncommon missense mutation (c.1420C>T, p.His474 Tyr) in the WT1 gene. In silico analysis, the variant was predicted “disease‐causing” by Mutation Taster. The mutated variant showed a weaker effect in inhibiting tumor cells than wild‐type WT1.ConclusionsThe uncommon missense mutation (c.1420C>T, p.His474 Tyr) in the WT1 gene may be a crucial marker in DDS.     

Correction: Tantalum(v) 1,3-propanediolate β-diketonate solution as a precursor to sol–gel derived,metal oxide thin films

Correction for ‘Tantalum(v) 1,3-propanediolate β-diketonate solution as a precursor to sol–gel derived, metal oxide thin films’ by Christopher Beale et al., RSC Adv., 2020, 10, 13737–13748, DOI: 10.1039/D0RA02558E.

The authors regret that the plasma treatment and printing parameters were reported incorrectly in the subsection “Deposition on a-SiO₂ for UV/Vis spectrophotometry” in the Experimental section of the original article.Before printing, the substrate for both samples was subjected to an argon plasma treatment for 5 minutes (150 W, 0.6 mbar). The plasma power is now corrected to be the same as stated in the “Deposition on a-SiO₂ for Raman/XRD” subsection, where originally it was incorrectly stated that “the power was set slightly higher” for the Raman/XRD samples. For both the acetylacetone and benzoylacetone inks, the inks were printed on their respective substrates with a 75 μm drop pitch having dimensions of 400 × 220 drops to create a uniform layer.The correct section is as follows:     

Continuous venovenous hemofiltration versus extended daily hemofiltration in patients with septic acute kidney injury: a retrospective cohort study

Introduction

Whether continuous venovenous hemofiltration (CVVHF) is superior to extended daily hemofiltration (EDHF) for the treatment of septic AKI is unknown. We compared the effect of CVVHF (greater than 72 hours) with EDHF (8 to 12 hours daily) on renal recovery and mortality in patients with severe sepsis or septic shock and concurrent acute kidney injury (AKI).

Methods

A retrospective analysis of 145 septic AKI patients who underwent renal replacement therapy (RRT) between July 2009 and May 2013 was performed. These patients were treated by CVVHF or EDHF with the same polyacrylonitrile membrane and bicarbonate-based buffer. The primary outcomes measured were occurrence of renal recovery and all-cause mortality by 60 days.

Results

Sixty-five and eighty patients were treated with CVVHF and EDHF, respectively. Patients in the CVVHF group had significantly higher recovery of renal function (50.77% of CVVHF group versus 32.50% in the EDHF group, P = 0.026). Median time to renal recovery was 17.26 days for CVVHF patients and 25.46 days for EDHF patients (P = 0.039). Sixty-day all-cause mortality was similar between CVVHF and EDHF groups (44.62%, and 46.25%, respectively; P = 0.844). 55.38% of patients on CVVHF and 28.75% on EDHF developed hypophosphatemia (P = 0.001). The other adverse events related to RRT did not differ between groups. On multivariate analysis, including physiologically clinical relevant variables, CVVHF therapy was significantly associated with recovery of renal function (HR 3.74; 95% CI 1.82 to 7.68; P < 0.001), but not with mortality (HR 0.69; 95% CI 0.34 to 1.41; P = 0.312).

Conclusions

Patients undergoing CVVHF therapy had significantly improved renal recovery independent of clinically relevant variables. The patients with septic AKI had similar 60-day all-cause mortality rates, regardless of type of RRT.     

Effects of perioperative dexmedetomidine infusion on renal function and microcirculation in kidney transplant recipients: a randomised controlled trial

ObjectiveIschemia-reperfusion injury affects postoperative transplanted kidney function in kidney transplant recipients. Dexmedetomidine was reported to attenuate ischemia-reperfusion injury and improve microcirculation, but its propensity to cause bradycardia and hypotension may adversely affect microcirculation. This study investigated the effect of dexmedetomidine on postoperative renal function and sublingual microcirculation in kidney recipients.MethodsThe enrolled kidney transplant recipients were randomly allocated to the control group or dexmedetomidine group. After anaesthesia induction, patients in the dexmedetomidine group received dexmedetomidine infusion until 2 h after surgery. Sublingual microcirculation was recorded using an incident dark-field video microscope and analysed. The primary outcomes were the creatinine level on a postoperative day 2 and total vessel density at 2 h after surgery.ResultsA total of 60 kidney recipients were analysed, and the creatinine levels on postoperative day 2 were significantly lower in the dexmedetomidine group than in the control group (1.5 (1.1–2.4) vs. 2.2 (1.7–3.0) mg/dL, median difference −0.6 (95% CI, −0.7 to −0.5) mg/dL, p = .018). On a postoperative day 7, the creatinine levels did not differ significantly between the two groups. Total vessel density at 2 h after surgery did not differ significantly between the two groups.ConclusionWe found that early postoperative renal function was better in kidney transplant recipients receiving dexmedetomidine infusion, but total vessel density was not significantly different between the intervention and control groups.

Key messages

• Ischemia-reperfusion injury affects postoperative transplanted kidney function, and dexmedetomidine was reported to attenuate ischemia-reperfusion injury and improve microcirculation in other clinical conditions.
• This study showed that early postoperative renal function was better in kidney transplant recipients receiving dexmedetomidine.
• Dexmedetomidine’s side effect of bradycardia and hypotension may affect microcirculation, our results revealed that the perioperative sublingual microcirculation did not differ significantly in kidney transplant recipients receiving dexmedetomidine.

     

A rapid “on–off–on” mitochondria-targeted phosphorescent probe for selective and consecutive detection of Cu2+ and cysteine in live cells and zebrafish

The detection of mitochondrial Cu²⁺ and cysteine is very important for investigating cellular functions or dysfunctions. In this study, we designed a novel cyclometalated iridium(iii) luminescence chemosensor Ir bearing a bidentate chelating pyrazolyl-pyridine ligand as a copper-specific receptor. The biocompatible and photostable Ir complex exhibited not only mitochondria-targeting properties but also an “on–off–on” type phosphorescence change for the reversible dual detection of Cu²⁺ and cysteine. Ir had a highly sensitive (detection limit = 20 nM) and selective sensor performance for Cu²⁺ in aqueous solution due to the formation of a non-phosphorescent Ir–Cu(ii) ensemble through 1 : 1 binding. According to the displacement approach, Ir was released from the Ir–Cu(ii) ensemble accompanied with “turn-on” phosphorescence in the presence of 0–10 μM cysteine, with a low detection limit of 54 nM. This “on–off–on” process could be accomplished within 30 s and repeated at least five times without significant loss of signal strength. Moreover, benefiting from its good permeability, low cytotoxicity, high efficiency, and anti-interference properties, Ir was found to be suitable for imaging and detecting mitochondrial Cu²⁺ and cysteine in living cells and zebrafish.

An iridium(iii) complex-based mitochondria targeting phosphorescent probe for selectively detecting Cu²⁺ and Cys in aqueous solution, living cells and zebrafish has been developed.     

Comparison of the Impact of “Fast Decline” in Residual Renal Function and “Initial Anuria” on Long-Term Outcomes in CAPD Patients

♦ Background: Residual renal function (RRF) is pivotal to long-term outcomes, while rapid RRF decline (RRFD) is associated with mortality risk for continuous ambulatory peritoneal dialysis (CAPD) patients. This study was conducted to compare the impact of “initial anuria” and rapid RRFD on the long-term prognosis of CAPD patients.♦ Method: According to the timing of anuria and the slope of RRFD, a total of 255 incident CAPD patients were divided into 3 groups. For the “anuria” group, anuria was detected from CAPD initiation and persisted for > 6 months (n = 27). Based on the median of the RRFD slope, the other 228 non-anuric patients were divided into a “slow decliner” group (n = 114), and a “rapid decliner” group (n = 114). The maximal observation period was 120 months.♦ Results: Logistic regression tests indicated that the “anuria” group was associated with previous hemodialysis > 3 months (odds ratio [OR]: 8.52, 95% confidence interval [CI]: 3.12 – 23.28), and female (OR: 0.29, 95% CI: 0.09 – 0.90), while the “fast decliner” group with higher Davies co-morbidity scores (DCS) (OR: 1.52; 95% CI: 1.08 – 2.14), body mass index (BMI) (OR: 1.12; 95% CI: 1.04 – 1.21), and male (OR: 1.12; 95% CI: 1.04 – 1.21). After adjusting for DCS, the “fast decliner” group (hazard ratio [HR]: 0.37; 95% CI: 0.17 – 0.80) showed a better outcome than that of the “anuria” group (reference = 1). Both baseline RRF (β = -0.24; p < 0.001) and DCS (β = -3.76; p < 0.001) showed inverse linear correlations to the slope of RRFD. From the Cox proportional analyses, higher baseline RRF (HR: 0.92; 95% CI: 0.88 –.97) and higher slope of RRFD (slower decline in RRF) (HR: 0.90; 95% CI: 0.85 – 0.96) were independent factors for less mortality risk in patients with DCS = 0. However, only a higher slope of RRFD (HR: 0.97; 95% CI: 0.94 – 0.99) was significant for better survival in CAPD patients with DCS > 0.♦ Conclusion: Compared to the baseline RRF, CAPD patients with co-morbidities that rapidly deteriorate RRFD are more crucially associated with long-term mortality risk.     

Effects of selective β1-adrenoceptor blockade on cardiovascular and renal function and circulating cytokines in ovine hyperdynamic sepsis

Introduction

Activation of the sympathetic nervous system has beneficial cardiovascular effects in sepsis, but there is also evidence that sympatholytics have beneficial actions in sepsis. We therefore determined the effect of selective β₁-adrenoceptor blockade on cardiac and renal function and cytokine release in ovine hyperdynamic sepsis.

Methods

Hyperdynamic sepsis was induced by infusion of live E. coli for 24 hours in nine conscious sheep instrumented with flow probes on the pulmonary and left renal artery. Cardiovascular and renal function and levels of plasma cytokines were determined in a control group and during selective β1-adrenoceptor blockade with atenolol (10 mg intravenous bolus then 0.125 mg/kg/h) from 8 to 24 hours of sepsis.

Results

Hyperdynamic sepsis was characterized by hypotension with increases in cardiac output (CO), heart rate (HR) and renal blood flow (RBF), and acute kidney injury. Atenolol caused sustained reductions in HR (P <0.001) and CO (P <0.001). Despite the lower CO the sepsis-induced fall in mean arterial pressure (MAP) was similar in both groups. The sepsis-induced increase in RBF, decrease in renal function and increase in arterial lactate were unaffected by atenolol. Sepsis increased plasma levels of tumour necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and IL-10. Atenolol caused a further increase in IL-10, but did not affect levels of TNF-α or IL-6.

Conclusions

In sepsis, selective β₁-adrenoceptor blockade reduced CO, but not MAP. During sepsis, atenolol did not alter the development of acute kidney injury or the levels of pro-inflammatory cytokines, but enhanced the release of IL-10. Atenolol appears safe in sepsis, has no deleterious cardiovascular or renal effects, and has an anti-inflammatory effect.