Targeting the TWEAK-Fn14 pathway prevents dysfunction in cardiac calcium handling after acute kidney injury.

Heart and kidney have a closely interrelated pathophysiology. Acute kidney injury (AKI) is associated with significantly increased rates of cardiovascular events, a relationship defined as cardiorenal syndrome type 3 (CRS3). The underlying mechanisms that trigger heart disease remain, however, unknown, particularly concerning the clinical impact of AKI on cardiac outcomes and overall mortality. Tumour necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor fibroblast growth factor-inducible 14 (Fn14) are independently involved in the pathogenesis of both heart and kidney failure, and recent studies have proposed TWEAK as a possible therapeutic target; however, its specific role in cardiac damage associated with CRS3 remains to be clarified. Firstly, we demonstrated in a retrospective longitudinal clinical study that soluble TWEAK plasma levels were a predictive biomarker of mortality in patients with AKI. Furthermore, the exogenous application of TWEAK to native ventricular cardiomyocytes induced relevant calcium (Ca2+ ) handling alterations. Next, we investigated the role of the TWEAK-Fn14 axis in cardiomyocyte function following renal ischaemia-reperfusion (I/R) injury in mice. We observed that TWEAK-Fn14 signalling was activated in the hearts of AKI mice. Mice also showed significantly altered intra-cardiomyocyte Ca2+ handling and arrhythmogenic Ca2+ events through an impairment in sarcoplasmic reticulum Ca2+ -adenosine triphosphatase 2a pump (SERCA2a ) and ryanodine receptor (RyR2 ) function. Administration of anti-TWEAK antibody after reperfusion significantly improved alterations in Ca2+ cycling and arrhythmogenic events and prevented SERCA2a and RyR2 modifications. In conclusion, this study establishes the relevance of the TWEAK-Fn14 pathway in cardiac dysfunction linked to CRS3, both as a predictor of mortality in patients with AKI and as a Ca2+ mishandling inducer in cardiomyocytes, and highlights the cardioprotective benefits of TWEAK targeting in CRS3. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Transmission of high arterial pressure into renal microvessels during venous-clamping augments ischaemia/reperfusion-induced acute kidney injury in anaesthetized rats.

AIM: In two recent studies, we observed that a 30-min renal vein clamping caused formation of interstitial haemorrhagic congestion in ischaemic and ischaemic/reperfused kidney along with the development of severer acute kidney injury (AKI) than renal artery or pedicle clamping. It was suggested that the transmission of high arterial pressure into renal microvessels during vein occlusion probably causes the occurrence of interstitial haemorrhagic congestion that augments AKI. The present investigation aimed to evaluate this suggestion by reducing renal perfusion pressure (RPP) during renal venous occlusion. METHODS: Anaesthetized male Sprague-Dawley rats were divided into three groups (n = 8), which underwent a 2-h reperfusion period following 30-min bilateral renal venous clamping along with reduced RPP (VIR-rRPP group) or without reduced RPP (VIR group) and an equivalent period after sham-operation (Sham group). RESULTS: The VIR-rRPP group compared with VIR group had lower levels of kidney malondialdehyde and tissue damages as epithelial injuries of proximal tubule and thick ascending limb, vascular congestion, intratubular cast and oedema, along with the less reductions in renal blood flow, creatinine clearance, Na+ -reabsorption, K+ and urea excretion, urine osmolality and free-water reabsorption. Importantly, the formation of intensive interstitial haemorrhagic congestion in the VIR group was not observed in the VIR-rRPP group. CONCLUSION: These results indicate that the transmission of high arterial pressure into renal microvessels during venous occlusion leads to rupturing of their walls and the formation of interstitial haemorrhagic congestion, which has an augmenting impact on ischaemia/reperfusion-induced renal structural damages and haemodynamic, excretory and urine-concentrating dysfunctions.

circ-AKT3 aggravates renal ischaemia-reperfusion injury via regulating miR-144-5p /Wnt/ß-catenin pathway and oxidative stress.

Renal ischaemia-reperfusion (RI/R) injury is one major pathological state of acute kidney injury (AKI) with a mortality rate ranking 50% to 80%. MiR-144-5p acts as a molecular trigger in various diseases. We presumed that miR-144-5p might be involved RI/R injury progression. We found that RI/R injury decreased miR-144-5p expression in rat models. MiR-144-5p downregulation promoted cell apoptosis rate and activated Wnt/ß-catenin signal in RI/R injury rats. By performing bioinformatic analysis, RIP, RNA pull-down, luciferase reporter experiments, we found that circ-AKT3 sponged to miR-144-5p and decreased its expression in RI/R injury rats. Moreover, we found that circ-AKT3 promoted cell apoptosis rate and activated Wnt/ß-catenin signal, and miR-144-5p mimic reversed the promotive effect of circ-AKT3 in rat models. We also found that circ-AKT3 increased the oxidative stress level in rat models. In conclusion, our study suggests that the circAKT3 is involved RI/R injury progression through regulating miR-144-5p/Wnt/ß-catenin pathway and oxidative stress.

Necrostatin-1 mitigates renal ischaemia-reperfusion injury - time dependent - via aborting the interacting protein kinase (RIPK-1)-induced inflammatory immune response.

The recently defined necroptosis process participates in the pathophysiology of several tissue injuries. Targeting the necroptosis mediator receptor-interacting protein kinase (RIPK1) by necrostatin-1 in different phases of ischaemia-reperfusion injury (IRI) may provide new insight into the protection against renal IRI. The rat groups included (n = 8 in each group): 1) Sham; 2) Renal IRI; 3) Necrostatin-1 treatment 20 min before ischaemia induction in a dose of 1.65 mg/kg/intravenous; 4) Necrostatin-1 injection just before reperfusion; 5) Necrostatin-1 injection 20 min after reperfusion establishment; and 6) drug injection at both the pre-ischaemia and at reperfusion time in the same dose. Timing dependent, necrostatin-1 diminished RIPK1 (p < 0.001), and aborted the necroptosis-induced renal cell injury. Necrostatin-1 decreased the renal chemokine (CXCL1), interleukin-6, intercellular adhesion molecule (ICAM-1), myeloperoxidase, and the nuclear factor (NFκB), concomitant with reduced inducible nitric oxide synthase (iNOS), inflammatory cell infiltration, and diminished cell death represented by apoptotic cell count and the BAX/Bcl2 protein ratio. In group 6, the cell injury was minimal and the renal functions (creatinine, BUN and creatinine clearance) were almost normalised. The inflammatory markers were diminished (p < 0.001) compared to the IRI group. The results were confirmed by histopathological examination. In conclusion, RIPK1 inhibition ameliorates the inflammatory immune response induced by renal IRI. The use of two doses was more beneficial as the pathophysiology of cell injury is characterised.

Corticomedullary shunting after ischaemia and reperfusion in the porcine kidney?

BACKGROUND: Renal perfusion may redistribute from cortex to medulla during systemic hypovolaemia and after renal ischaemia for other reasons, but there is no consensus on this matter. We studied renal perfusion after renal ischaemia and reperfusion. METHODS: Renal perfusion distribution was examined by use of 153Gadolinium-labeled microspheres (MS) after 2 h (hrs) and 4 h ischaemia of the pig kidney followed by 4 h of reperfusion. Intra-arterial injected MS are trapped in the glomeruli in renal cortex, which means that MS are not present in the medulla under normal physiological conditions. RESULTS: Visual evaluation after reperfusion demonstrated that MS redistributed from the renal cortex to the medulla in 6 out of 16 pigs (38%) subjected to 4 h ischaemia and in one out of 18 pigs subjected to 2 h ischaemia. Central renal uptake of MS covering the medullary/total renal uptake was significantly higher in kidneys subjected to 4 h ischaemia compared with pigs subjected to 2 h ischaemia (69 ± 5% vs. 63 ± 1%, p < 0.001), and also significantly higher than in the contralateral kidney (69 ± 5% vs. 63 ± 2%, p < 0.001). Analysis of blood and urine demonstrated no presence of radioactivity. CONCLUSION: The study demonstrated the presence of MS in the renal medulla in response to renal ischaemia and reperfusion suggesting that severe ischaemia and reperfusion of the pig kidney leads to opening of functional shunts bypassing glomeruli.

LncRNA TUG1 attenuates ischaemia-reperfusion-induced apoptosis of renal tubular epithelial cells by sponging miR-144-3p via targeting Nrf2.

Renal ischaemia/reperfusion (I/R) injury may induce kidney damage and dysfunction, in which oxidative stress and apoptosis play important roles. Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) are reported to be closely related to renal I/R, but the specific molecular mechanism is still unclear. The purpose of this research was to explore the regulatory effect of lncRNA TUG1 on oxidative stress and apoptosis in renal I/R injury. This research revealed that in renal I/R injury and hypoxia/reperfusion (H/R) injury in vitro, the expression level of lncRNA TUG1 was upregulated, and oxidative stress levels and apoptosis levels were negatively correlated with the expression level of lncRNA TUG1. Using bioinformatics databases such as TargetScan and microRNA.org, microRNA-144-3p (miR-144-3p) was predicted to be involved in the association between lncRNA TUG1 and Nrf2. This study confirmed that the level of miR-144-3p was significantly reduced following renal I/R injury and H/R injury in vitro, and miR-144-3p was determined to target Nrf2 and inhibit its expression. In addition, lncRNA TUG1 can reduce the inhibitory effect of miR-144-3p on Nrf2 by sponging miR-144-3p. In summary, our research shows that lncRNA TUG1 regulates oxidative stress and apoptosis during renal I/R injury through the miR-144-3p/Nrf2 axis, which may be a new treatment target for renal I/R injury.

Remote liver injury following acute renal ischaemia-reperfusion: involvement of circulating exosomal miR-687 and regulation by thymoquinone.

NEW FINDINGS: What is the central question of this study? What is the role of circulating exosomal miR-687 in remote hepatic injury following renal ischaemia-reperfusion injury (IRI) and does thymoquinone have a modulatory impact? What is the main finding and its importance? Exosomal miR-687 was expressed in renal IRI, entered the circulation and was deposited in the liver. Liver exosomal miR-687 was correlated with liver inflammation and apoptosis. Thymoquinone aborted the renal production of exosomal miR-687 and its further circulation to the liver. ABSTRACT: The pathophysiology of remote hepatic injury following acute renal ischaemia-reperfusion injury (IRI) is of particular clinical interest. Secreted small non-coding microRNA (miRs) are thought to exist in exosome-encapsulated form. Thymoquinone (TQ) is the main bioactive ingredient of Nigella sativa and has several renoprotective actions. We expected exosomal miR-687 to be relevant as it could act as a humoral mediator, with possible modulation by TQ. Thirty adult male Wister albino rats were assigned to three groups (n = 10); (1) sham-operated, (2) renal ischaemia-reperfusion injury (IRI), and (3) renal IRI pre-treated with TQ 10 mg/kg/day i.v. (TQ-IRI) for 10 days in addition to a dose administered at reperfusion onset. Following 24 h of reperfusion, the IRI group showed renal tissue hypoxia-inducible factor upregulation (P < 0.001). Electron microscopy images of exosomes and analysis of miR-687 revealed elevated levels, which appeared in the circulation. Large amounts of exosomal miR-687 were transmitted to the liver tissue. In the IRI group, liver transaminases (alanine aminotransferase, aspartate aminotransferase) were markedly (P < 0.001) elevated. The hepatic tissue inflammatory markers (vascular cell adhesion molecule-1, myeloperoxidase, monocyte chemotactic protein-1 and nuclear factor-κB) were upregulated (P < 0.001) accompanied with elevated caspase-3. TQ suppressed (P < 0.001) the renal expression and release of exosomal miR-687 into the circulation and its further deposition in the liver tissue; consequently, TQ diminished (P < 0.001) liver tissue inflammation and cellular apoptosis. The results were confirmed by histological tissue assessment. In conclusion, exosomal miR-687 liberated from injured renal tissues into the circulation may be an important factor in inducing remote hepatic injury. Exosomal miR-687 inhibition by TQ protected both renal and hepatic tissues from injury.

Clemaichinenoside protects renal tubular epithelial cells from hypoxia/reoxygenation injury in vitro through activating the Nrf2/HO-1 signalling pathway.

Renal ischaemia/reperfusion (I/R) is a major cause of acute renal failure with increased morbidity, mortality, and prolonged hospitalizations. Clematichinenoside (AR), a triterpenoid saponin isolated from the roots of Clematis chinensis, was reported to possess a protective effect against I/R injury. However, the effect of AR on renal I/R injury has not been evaluated. This study aims to examine the effect of AR on an in vitro I/R model in human proximal tubular epithelial cells HK-2. HK-2 cells were subjected to hypoxia/reoxygenation (H/R) stimulation to mimic I/R in vitro. The results showed that AR improved cell viability of H/R-stimulated HK-2 cells. AR pretreatment resulted in decreased production of reactive oxygen species (ROS) and malondialdehyde (MDA), as well as increased in superoxide dismutase (SOD) activity in H/R-stimulated HK-2 cells. In addition, AR also presented an anti-inflammatory activity, as evidenced by decreased secretion of pro-inflammatory cytokines including IL-6, IL-1ß, and TNF-α. Moreover, apoptotic rate was markedly decreased in HK-2 cells pretreated with AR. The bax expression was decreased, while bcl-2 expression was increased by AR pretreatment. Furthermore, AR enhanced the H/R-stimulated activation of the Nrf2/HO-1 signalling pathway in HK-2 cells. In conclusion, these findings indicated that AR protected HK-2 cells from H/R-induced cell injury via regulating the Nrf2/HO-1 signalling pathway.

Cold Renal Perfusion During Simulation of Juxtarenal Aortic Aneurysm Repair Reduces Systemic Oxidative Stress and Sigmoid Damage in Rats.

OBJECTIVES: Juxtarenal aortic surgery induces renal ischaemia reperfusion, which contributes to systemic inflammatory tissue injury and remote organ damage. Renal cooling during suprarenal cross clamping has been shown to reduce renal damage. It is hypothesised that renal cooling during suprarenal cross clamping also has systemic effects and could decrease damage to other organs, like the sigmoid colon. METHODS: Open juxtarenal aortic aneurysm repair was simulated in 28 male Wistar rats with suprarenal cross clamping for 45 min, followed by 20 min of infrarenal aortic clamping. Four groups were created: sham, no, warm (37 °C saline), and cold (4 °C saline) renal perfusion during suprarenal cross clamping. Primary outcomes were renal damage and sigmoid damage. To assess renal damage, procedure completion serum creatinine rises were measured. Peri-operative microcirculatory flow ratios were determined in the sigmoid using laser Doppler flux. Semi-quantitative immunofluorescence microscopy was used to measure alterations in systemic inflammation parameters, including reactive oxygen species (ROS) production in circulating leukocytes and leukocyte infiltration in the sigmoid. Sigmoid damage was assessed using digestive enzyme (intestinal fatty acid binding protein - I-FABP) leakage, a marker of intestinal integrity. RESULTS: Suprarenal cross clamping caused deterioration of all systemic parameters. Only cold renal perfusion protected against serum creatinine rise: 0.45 mg/dL without renal perfusion, 0.33 mg/dL, and 0.14 mg/dL (p = .009) with warm and cold perfusion, respectively. Microcirculation in the sigmoid was attenuated with warm (p = .002) and cold renal perfusion (p = .002). A smaller increase of ROS production (p = .034) was seen only after cold perfusion, while leukocyte infiltration in the sigmoid colon decreased after warm (p = .006) and cold perfusion (p = .018). Finally, digestive enzyme leakage increased more without (1.5AU) than with warm (1.3AU; p = .007) and cold renal perfusion (1.2AU; p = .002). CONCLUSIONS: Renal ischaemia/reperfusion injury after suprarenal cross clamping decreased microcirculatory flow, increased systemic ROS production, leukocyte infiltration, and I-FABP leakage in the sigmoid colon. Cold renal perfusion was superior to warm perfusion and reduced renal damage and had beneficial systemic effects, reducing sigmoid damage in this experimental study.

Lipoxin A4 ameliorates renal ischaemia-reperfusion-induced acute lung injury in rats.

Lipoxin A4 (LA4), a bioactive product of arachidonic acid, has been shown to exert strong anti-inflammatory activity. By contrast, the anti-inflammatory action of LA4 in a renal ischaemia-reperfusion (RIR)-mediated acute lung inflammation (ALI) model and the potential pathogenesis of the condition is still unclear. The aim of the current research was to investigate the effect of LA4 on RIR-induced ALI. The rat ALI model was induced by RIR. LA4 was injected via the tail vein immediately after RIR. The results indicate that LA4 markedly inhibits inflammatory cells infiltration, attenuates myeloperoxidase activity, and reduces the concentration of inflammatory mediators and Toll-like receptor 4 (TLR4) in RIR-induced ALI. Furthermore, LA4 suppressed nuclear factor kappa B (NF-κB) p65 and mitogen-activated protein kinase (MAPK) activation. The protective effect of LA4 in RIR-stimulated ALI was reversed by BOC-2 (an antagonist of the LA4 receptor). These results indicate that LA4 exerts powerful anti-inflammatory functions in RIR-induced ALI by attenuating TLR4 expression via MAPK and NF-κB signalling. Accordingly, LA4 might be an underlying treatment drug for RIR-induced ALI.

Effect of long non-coding RNA growth arrest-specific 5 on apoptosis in renal ischaemia/reperfusion injury.

AIM: Long non-coding RNA (lncRNAs) have been shown to play a critical role in a variety of pathophysiological processes, such as cell proliferation, apoptosis and migration. However, there were few studies addressing the function of lncRNAs in renal ischaemia/reperfusion (I/R) injury. Apoptosis is an important pathogenesis during I/R injury. Here, we identified the effect of hypoxia-responsive lncRNA growth arrest-specific 5 (GAS5) on apoptosis in renal I/R injury. METHODS: Ischaemia/reperfusion injury in mice or hypoxia/re-oxygenation (H/R) in human proximal renal tubular epithelial cells (HK-2) was practiced to induce apoptosis. The kidneys and blood were collected at 24 h after reperfusion. The GAS5 messenger RNA (mRNA) expression and apoptosis-related gene mRNA and protein levels, including p53, cellular inhibitor of apoptosis protein 2 (cIAP2) and thrombospondin-1 (TSP-1), were analysed. GAS5 small-interfering RNA was transfected with H/R induced cells. Over-expression of GAS5 was performed by plasmid transfection. RESULTS: Apoptotic cells significantly increased in I/R-injured kidneys. GAS5 could be up-regulated in kidneys at 24 h after reperfusion and 3 h after re-oxygenation, combined with increased expression of its downstream apoptosis-related proteins p53 and cIAP2. GAS5 small-interfering RNA treatment down-regulated the mRNA and protein levels of p53 and TSP-1, and attenuated apoptosis induced by H/R in HK-2 cells. Conversely, over-expression of GAS5 up-regulated the mRNA and protein levels of p53 and TSP-1, and promoted apoptosis in HK-2 cells. CONCLUSION: Long non-coding RNA GAS5 induced by I/R injury could promote apoptosis in kidney. TSP-1 might be one of the downstream effectors of GAS5, which will be explored in the future.

Mammalian STE20-Like Kinase 1 Deletion Alleviates Renal Ischaemia-Reperfusion Injury via Modulating Mitophagy and the AMPK-YAP Signalling Pathway.

BACKGROUND/AIMS: The aim of our study is to investigate the molecular mechanism by which mammalian STE20-like kinase 1 (Mst1) participates in renal I/R injury through modifying mitophagy and the AMPK-YAP signalling pathway. METHODS: WT mice and Mst1-knockout mice were subjected to renal ischaemia-reperfusion (I/R) in vivo. In vitro, the hypoxia-reoxygenation model was used with renal tubular epithelial cells to mimic renal I/R injury. Mitochondrial function was monitored via western blotting and immunofluorescence. Pathway blocker and siRNA knockout technology were used to establish the role of the AMPK-YAP signalling pathway in Mst1-mediated mitochondrial apoptosis in the setting of renal I/R injury. RESULTS: Our data demonstrated that Mst1 expression was upregulated in response to renal I/R injury in vivo, and a higher Mst1 content was positively associated with renal dysfunction and more tubular epithelial cell apoptosis. However, genetic ablation of Mst1 improved renal function, alleviated reperfusion-mediated tubular epithelial cell apoptosis, and attenuated the vulnerability of kidney to I/R injury. In vitro, Mst1 upregulation induced mitochondrial damage including mitochondrial potential reduction, ROS overloading, cyt-c liberation and caspase-9 apoptotic pathway activation. At the molecular levels, I/R-mediated mitochondrial damage via repressing mitophagy and Mst1 suppressed mitophagy via inactivating AMPK signalling pathway and dowregulating OPA1 expression. Re-activation of AMPK-YAP-OPA1 signalling pathway provided a survival advantage for the tubular epithelial cell in the context of renal I/R injury by repressing mitochondrial fission. CONCLUSION: Overall, our results demonstrate that the pathogenesis of renal I/R injury is closely associated with an increase in Mst1 expression and the inactive AMPK-YAP-OPA1 signalling pathway. Based on this, strategies to repress Mst1 expression and activate mitophagy could serve as therapeutic targets to treat kidney ischaemia-reperfusion injury.

miR-21 contributes to renal protection by targeting prolyl hydroxylase domain protein 2 in delayed ischaemic preconditioning.

AIM: Upregulation of miR-21 in renal ischaemic preconditioning (IPC) was associated with increased hypoxia inducible factor (HIF)-1α expression. Hypoxic induction of HIF-1α is mediated by inhibition of prolyl hydroxylase domain protein 2 (PHD2) .We hypothesized that miR-21 regulated HIF-1α by targeting PHD2 in the renal IPC. METHODS: Luciferase reporter assay examined if miR-21 target the 3'-untranslated region of PHD2. In vitro, human proximal tubular cell line (HK-2) was incubated in hypoxia or hypoxia/ reoxygenation condition. Kidneys of Mice were respectively subjected to ischaemia/reperfusion injury (IRI) and IPC. Locked nucleic acid (LNA) modified anti-miR-21 was used to knockdown miR-21. Serum creatinine and histological changes estimated the renal injury. Levels of HIF-1α, PHD2, VEGF and miR-21 were examined by western blot or real-time PCR. RESULT: miR-21 targeting of PHD2 was confirmed by 3'-untranslated region reporter assay. miR-21 was significantly upregulated by hypoxia/reoxygenation in HK-2 cell, while PHD2 protein level decreased significantly. LNA anti-miR-21 significantly repressed miR-21 levels and increased the abundance of PHD2. In vivo, IPC upregulated miR-21 expression 24 h after the second ischaemia, while PHD2 expression decreased significantly with upregulation of HIF-1α protein and VEGF mRNA. MiR-21 induced by delayed IPC was effectively inhibited by the LNA anti-miR-21. With downregulation of miR-21, the protection of delayed IPC was attenuated and PHD2 protein was increased. Furthermore, upregulation of HIF-1α and VEGF were abolished after the LNA anti-miR-21 treatment. CONCLUSION: miR-21 could protect kidney against IRI via HIF-1α by inhibiting its target PHD2.The study suggested a new relationship between miR-21 and HIF-1α.

Evaluation of functional outcomes after laparoscopic partial nephrectomy using renal scintigraphy: clamped vs clampless technique.

OBJECTIVES: To examine differences in postoperative renal functional outcomes when comparing clampless with conventional laparoscopic partial nephrectomy (LPN) by using renal scintigraphy, and to identify the predictors of poorer postoperative renal functional outcomes after clampless LPN. PATIENTS AND METHODS: Between September 2010 and September 2012, 87 patients with renal masses suitable for LPN were prospectively enrolled in the study. From September 2010 to September 2011, LPN with renal artery clamping was performed and from September 2011 to September 2012 clampless LPN (no clamping of renal artery) was performed. Patients who underwent clampless LPN were unselected and consecutive, and the procedure was performed at the end of surgeon's learning curve. Patients were divided into two groups according to warm ischaemia time (WIT): group A, conventional LPN and group B, clampless-LPN (WIT = 0 min). Demographic and peri-operative data were collected and analysed and functional outcomes were evaluated using biochemical markers and renal scintigraphy at baseline and at 3 months after surgery. The percentage loss of renal function, evaluated according to renal scintigraphy, was calculated. Chi-squared and Student's t-tests were carried out and regression analysis was performed. RESULTS: Group A was found to be similar to group B in all variables measured except for WIT and blood loss (P < 0.001). The percentage reduction in renal scintigraphy values was not significantly different between the groups (reductions of 5% in group A and 6% in group B for split renal function [SRF] and 12% in group A and 17% in group B for estimated renal plasmatic flow [ERPF]; P = 0.587 and P = 0.083, respectively). Multivariate analysis in group B showed that the lower the baseline values of SRF and ERPF, the poorer the postoperative functional outcome of the treated kidney. CONCLUSIONS: In our experience, even clampless LPN was not found to be functionally harmless. The patients who benefitted most from a clampless approach were those with the poorest baseline renal function.

Erythropoietin pretreatment ameliorates renal ischaemia-reperfusion injury by activating PI3K/Akt signalling.

AIM: Renal ischaemia-reperfusion (I/R) injury, a primary cause of acute renal failure, can induce high morbidity and mortality. This study aimed to explore the effect of erythropoietin on renal I/R injury and its underlying mechanism. METHODS: Fifty male Sprague-Dawley rats were randomly allocated to three groups (n = 10): the sham group, the renal ischaemia-reperfusion-saline (IRI) group, and the IRI+-Erythropoietin (EPO) group. Erythropoietin (250, 500, 1000 U/kg) was intraperitoneally injected 30 min before inducing I/R. Renal I/R injury were induced by clamping the left renal artery for 30 min followed by reperfusion, along with a contralateral nephrectomy. Renal function and histological damage were determined after 24 h reperfusion. The expression of pro-inflammatory cytokines interleukin-6 (IL-6), interleukin-1 ß (IL-1ß), and tumour necrosis factor-α (TNF-α) in the serum and renal tissue were evaluated by enzyme linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR), respectively. Further, the effects of erythropoietin on PI3K/Akt signalling, erythropoietin receptor (EPOR) and nuclear factor (NF)-κB activation were measured by Western blotting. RESULTS: Erythropoietin pretreatment can significantly decrease the level of renal dysfunction in a dose-dependent manner, attenuated the renal histological changes, the expression of TNF-α, IL-1ß, and IL-6, the levels of reactive oxygen species (ROS) production and NF-κB p65 phosphorylation in renal tissue upon IRI. Moreover, erythropoietin pretreatment could further activate the PI3K/Akt signalling and induced EPOR activity. CONCLUSIONS: Erythropoietin pretreatment could attenuate renal I/R injury by suppressing inflammation, which was associated with activating PI3K/Akt signalling though EPOR activation. Our findings suggest that erythropoietin may be a novel practical strategy to prevent renal I/R injury.

Protection of Wistar-Furth rats against postischaemic acute renal injury: role for nitric oxide and thromboxane?

The Wistar-Furth (WF) rat strain is usually used in models of full major histocompatibility complex-mismatched kidney transplantation. Because these rats have been demonstrated to be resistant to several models of chronic kidney disease, the aim of the present study was to investigate their potential resistance to renal ischaemia-reperfusion (I/R) injury compared with another strain, namely Wistar-Hanover (WH) rats. Anaesthetized male WH and WF rats were submitted to I/R by occlusion of the left renal artery and contralateral nephrectomy. Urine, blood and tissue samples were collected at different time points after I/R to evaluate renal function, inflammation and tubular injury, along with determination of nitric oxide synthase (NOS) expression and thromboxane A2 (TxA2 ) production. Post-ischaemic renal function was better preserved in WF than WH rats, as evidenced by reduced levels of creatininaemia, urinary neutrophil gelatinase-associated lipocalin excretion and proteinuria. In addition, WF rats had less intrarenal inflammation than WH rats after I/R injury. These observations were associated with maintenance of neuronal NOS expression, along with lower induction of inducible NOS expression in WF versus WH rats. Moreover, WF rats excreted a significantly lower amount of TxB2 . The results indicate that WF rats are more resistant to an I/R injury than WH rats in terms of renal function and inflammation. These observations are associated with differential regulation of intrarenal NOS expression, as well as a reduction in thromboxane production, which could contribute to a better outcome for the postischaemic kidney in WF rats.

Efficacy of metamizole to prevent kidney injury after renal-ischaemic reperfusion injury in Wistar rats.

Background: Renal ischaemia-reperfusion injury (RIRI) is a common kidney procedure complication due to temporary blood flow interruption, leading to kidney injuries. This study aimed to analyze the effect of metamizole on the levels of interleukin-18 (IL-18), neutrophil-gelatinase-associated lipocalin (NGAL), myeloperoxidase (MPO), and histopathological changes in rats with RIRI. Materials and methods: Animal pre-clinical design study was used. Thirty-two male Wistar rats (Rattus norvegicus) were divided into four groups: negative control, positive control, M100, and M200. Blood samples were collected by intracardiac puncture, followed by bilateral nephrectomy and analyzed histopathologically. Results: Significant difference in IL-18 levels between positive control vs negative control (114.1 + 12.07 vs. 94.0 + 11.4; P = 0.019) and positive control vs M100 (114.1 + 12.07 vs. 86.9 + 8.34; P = 0.007). There was no difference in NGAL. M100 group had the lowest serum MPO levels (14.78+2.01), there was a significant difference in MPO levels in all pairwise analyses. There was a difference in cumulative EGTI scores among the study groups [positive 10.5 (8-11) vs. negative 9 (7-10) vs. M100 9 (7-10) vs. M200 9 (7-11); P = 0.021]. Conclusion: Metamizole 100 mg/kgBW can reduce IL-18 and MPO levels in RIRI, giving more optimal results without affecting NGAL levels. Metamizole administration can reduce cumulative EGTI scores in RIRI, both at doses of 100 mg/kgBW and 200 mg/kgBW. This study shows that Metamizole can be used to prevent kidney injury caused by RIRI. IL-18 and MPO can be biomarkers in predicting kidney injury in RIRI.

Acute treatment with relaxin protects the kidney against ischaemia/reperfusion injury.

Although recent preclinical and clinical studies have demonstrated that recombinant human relaxin (rhRLX) may have important therapeutic potential in acute heart failure and chronic kidney diseases, the effects of acute rhRLX administration against renal ischaemia/reperfusion (I/R) injury have never been investigated. Using a rat model of 1-hr bilateral renal artery occlusion followed by 6-hr reperfusion, we investigated the effects of rhRLX (5 µg/Kg i.v.) given both at the beginning and after 3 hrs of reperfusion. Acute rhRLX administration attenuated the functional renal injury (increase in serum urea and creatinine), glomerular dysfunction (decrease in creatinine clearance) and tubular dysfunction (increase in urinary excretion of N-acetyl-ß-glucosaminidase) evoked by renal I/R. These beneficial effects were accompanied by a significant reduction in local lipid peroxidation, free radical-induced DNA damage and increase in the expression/activity of the endogenous antioxidant enzymes Mn- and CuZn-superoxide dismutases (SOD). Furthermore, rhRLX administration attenuated the increase in leucocyte activation, as suggested by inhibition of myeloperoxidase activity, intercellular-adhesion-molecule-1 expression, interleukin (IL)-1ß, IL-18 and tumour necrosis factor-α production as well as increase in IL-10 production. Interestingly, the reduced oxidative stress status and neutrophil activation here reported were associated with rhRLX-induced activation of endothelial nitric oxide synthase and up-regulation of inducible nitric oxide synthase, possibly secondary to activation of Akt and the extracellular signal-regulated protein kinase (ERK) 1/2, respectively. Thus, we report herein that rhRLX protects the kidney against I/R injury by a mechanism that involves changes in nitric oxide signalling pathway.

Margins, ischaemia and complications rate after laparoscopic partial nephrectomy: impact of learning curve and tumour anatomical characteristics.

OBJECTIVES: To present our laparoscopic partial nephrectomy (LPN) results according to the margin, ischaemia and complications (MIC) system recently proposed for the standardized reporting of partial nephrectomy (PN) outcomes. To assess the role of learning curve and tumour anatomical characteristics on the outcomes by using MIC system. PATIENTS AND METHODS: Data were obtained from our prospectively maintained LPN database, including only patients who underwent LPN performed with vascular clamping. According to the MIC system definition, the goal of LPN was reached (i.e. MIC was achieved) when surgical margins were negative, warm ischaemia time (WIT) was <20 min and no major complications occurred. Patients were stratified by quartiles of distribution, named LPN eras 1-4, and MIC rates in different LPN eras were compared, evaluating the impact of learning curve and tumour anatomical characteristics (as assessed by Preoperative Aspects and Dimensions Used for an Anatomical [PADUA] score on the outcomes. RESULTS: The study population consisted of 206 patients. The overall MIC rate was 63.1%: it progressively increased along the learning curve, reaching 84.9% in LPN era 4 (P < 0.001). PADUA-score risk group categories were inversely correlated with MIC score (P = 0.001). When simultaneously considering the effects of both LPN eras and PADUA-score risk group categories, a trend towards a higher MIC rate was found in the latest series, regardless of tumour anatomical characteristics. When MIC score components were separately analysed, WIT decreased significantly from LPN era 1 to LPN era 4 (P < 0.001) and from PADUA-score risk group categories 3 to 1 (P = 0.001) A trend towards a decrease in the complication rate along the learning curve was observed (P = 0.251), while LPN era and PADUA score together significantly influenced the complications rate (P < 0.001). The positive surgical margin rate was very low (2.9% overall) and stable throughout the case study. CONCLUSION: The MIC rate increased with surgeon's experience and decreased when complex lesions were treated. The MIC system was found to be an easy, useful and reproducible tool to report LPN data series.

Protective effect of saxagliptin against renal ischaemia reperfusion injury in rats.

Saxagliptin is an effective and selective dipeptidyl peptidase-4 (DPP-4) inhibitor. This study was designed to determine possible protective effects of saxagliptin against damage caused by renal ischaemia/reperfusion (I/R) in rats. In this study, 40 rats were divided into 4 groups (n = 10 for each). Group 1 (Control), Group 2 (I/R) in both kidneys ischaemia of 45 min was performed, and then reperfusion was applied for 24 h. Saxagliptin (Group 3: 2 mg/kg and Group 4: 10 mg/kg) was administered by oral gavage to the animals in treatment groups, before the I/R. Saxagliptin decreased the markers (BUN, Cre, NGAL, KIM-1 and IL-18) of acute renal damage in blood and kidney tissue. Saxagliptin provided increase in antioxidant enzyme levels and decrease in MDA and apoptosis. Histological results showed that the administration of saxagliptin exhibited a protective effect against renal damage caused by I/R. These results indicates that saxagliptin provide protection against kidney injury caused by I/R.