Animal models of acute renal failure

Enoxaparin prevents CXCL16/ADAM10-mediated cisplatin renal toxicity: Role of the coagulation system and the transcriptional factor NF-κB

BACKGROUND AND AIMS

C-X-C ligand 16 (CXCL16) is an exceptional chemokine that is expressed as transmembrane and soluble forms. Our aim is to shed lights on the role of CXCL16/ADAM10 (a disintegrin and metalloproteinase) in cisplatin (CP)-induced renal toxicity as well as possible protective effect of enoxaparin.

MAIN METHODS

Male albino mice were injected with CP (30 mg/kg, i.p.) in the presence or absence of enoxaparin (ENOX) (5 mg/kg, i.p.). Renal toxicity markers, serum level of cystatin-c, complete blood count (CBC), prothrombin time (Pt) and tissue expression of CXCL16, ADAM10, cluster of differentiation 3 (CD3), fibrinogen, tissue factor (TF), nuclear factor-κB (NF-κB) and tumour necrosis factor α (TNF-α) were measured. Besides, serum CXCL16 and histopathology were also analyzed.

KEY FINDINGS

CP increased renal toxicity markers, renal expression of CXCL16/ADAM10, fibrinogen, TF and CD3 tissue expression in a time-dependent manner, and elevated serum cystatin-c, CXCL16 and tissue TNF-α, NF-κB. Alternatively, ENOX restored the deteriorated parameters and reduced tissue level of NF-κB.

SIGNIFICANCE

This report, for the first time, showed that soluble CXCL16 resulting from ADAM10 cleavage may recruit T-cells to the renal glomeruli and tubules in CP toxicity. Furthermore, TF and fibrin, have similar expression and location pattern like CXCL16 and ADAM10 suggesting their possible interrelation. ENOX successfully restored the deteriorated parameters suggesting it may be an effective nephroprotective adjuvant therapy.

Stevioside protects against rhabdomyolysis-induced acute kidney injury through PPAR-γ agonism in rats

We explored the potential role of peroxisome proliferator activated receptor-γ (PPAR-γ) in stevioside-mediated renoprotection using rhabdomyolysis-induced acute kidney injury (AKI) model in rats. Rhabdomyolysis refers to intense skeletal muscle damage, which further causes AKI. Glycerol (50% w/v, 8 ml/kg) was injected intramuscularly in rats to induce rhabdomyolysis. After 24 hr, AKI was demonstrated by quantifying serum creatinine, urea, creatinine clearance, microproteinuria, and electrolytes in rats. Further, oxidative stress was measured by assaying thiobarbituric acid reactive substances, generation of superoxide anion, and reduced glutathione levels. Additionally, serum creatine kinase (CK) level was assayed to determine glycerol-induced muscle damage in rats. Pathological changes in rat kidneys were studied using hematoxylin-eosin and periodic acid Schiff staining. Moreover, the expression of apoptotic markers (Bcl-2, Bax) in rat kidneys was demonstrated by immunohistochemistry. Stevioside (10, 25, and 50 mg/kg) was administered to rats, prior to the induction of AKI. In a separate group, bisphenol A diglycidyl ether (BADGE, 30 mg/kg), a PPAR-γ receptor antagonist was given prior to stevioside administration, which was followed by rhabdomyolysis-induced AKI in rats. The significant alteration in biochemical and histological parameters in rats indicated AKI, which was attenuated by stevioside treatment. Pretreatment with BADGE abrogated stevioside-mediated renoprotection, which is suggestive of the involvement of PPAR-γ in its renoprotective effect. In conclusion, stevioside protects against rhabdomyolysis-induced AKI, which may be attributed to modulation of PPAR-γ expression.

Proximal Tubular Vacuolization and Hypersensitivity to Drug-Induced Nephrotoxicity in Male Mice With Decreased Expression of the NADPH-Cytochrome P450 Reductase

The effect of variations in the expression of cytochrome P450 reductase (CPR or POR) is determined in mice with decreased POR expression to identify potential vulnerabilities in people with low POR expression. There is an age-dependent appearance of increasing vacuolization in the proximal tubules of the renal cortex in 4- to 9-month-old male (but not female) Cpr-low (CL) mice. These mice have low POR expression in all cells of the body and upregulation of lysosome-associated membrane protein 1 expression in the renal cortex. Vacuolization is also seen in extrahepatic CL and extrarenal CL male mice, but not in mice with tissue-specific Por deletion in liver, intestinal epithelium, or kidney. The occurrence of vacuolization is accompanied by increases in serum blood-urea-nitrogen levels. Male CL mice are hypersensitive to cisplatin- and gentamicin-induced renal toxicity at 3 months of age, before proximal tubular (PT) vacuoles are detectable. At doses that do not cause renal toxicity in wild-type mice, both drugs cause substantial increases in serum blood-urea-nitrogen levels and PT vacuolization in male but not female CL mice. The hypersensitivity to drug-induced renal toxicity is accompanied by increases in circulating drug levels. These novel findings demonstrate deficiency of renal function in mice with globally reduced POR expression and suggest that low POR expression may be a risk factor for drug-induced nephrotoxicity in humans.

Ferrotoxicity and its amelioration by endogenous vitamin D in experimental acute kidney injury

This work provides in-depth insights on catalytic iron-induced cytotoxicity and the resultant triggering of endogenous vitamin D synthesis in experimental acute kidney injury. Our results reveal significantly elevated levels of catalytic iron culminating in oxidant-mediated renal injury and a concomitant increase in 1,25-dihdyroxyvitamin D3 levels. Also, changes in other iron-related proteins including transferrin, ferritin, and hepcidin were observed both in the serum as well as in their mRNA expression. We consider all these findings vital since no connection between catalytic iron and vitamin D has been established so far. Furthermore, we believe that this work provides new and interesting results, with catalytic iron emerging as an important target in ameliorating renal cellular injury, possibly by timely administration of vitamin D. It also needs to be seen if these observations made in rats could be translated to humans by means of robust clinical trials.

Luteolin Attenuates Glycerol-Induced Acute Renal Failure and Cardiac Complications Through Modulation of Kim-1/NF-κB/Nrf2 Signaling Pathways

Acute renal failure (ARF) has been documented as a life-threatening disease with high morbidity and mortality. We investigated the protective effect of Luteolin against ARF. In this study, forty-male Wistar albino rats were randomly divided into four groups (n = 10). Group A received normal saline. Group B received glycerol (10 ml/kg BW, 50% v/v in sterile saline, i.m.). Groups C and D were pretreated with Luteolin 100 and 200 mg/kg for 7 days, and thereafter administered Glycerol (10 ml/kg BW, 50% v/v in sterile saline, i.m.). Administration of glycerol significantly increased systolic blood pressure, diastolic blood pressure and mean arterial pressure. Renal protein carbonyl and xanthine oxidase increased significantly while significant reduction in the activity of renal glutathione peroxidase, glutathione S-transferase and glutathione reductase was observed in the glycerol intoxicated rats. Furthermore, administration of glycerol led to significant increases in serum creatinine and blood urea nitrogen together with reduction in nitric oxide (NO) bioavailability. Immunohistochemistry revealed that glycerol intoxication enhanced expressions of kidney injury molecule 1, nuclear factor kappa beta and cardiac troponin (CTnI). However, Luteolin pretreatment normalized blood pressure, reduced markers of oxidative stress, renal damage, and improved NO bioavailability. Luteolin also downregulated the expressions of kidney injury molecule 1, nuclear factor kappa beta and cardiac troponin. Together, Luteolin might open a novel therapeutic window for the treatment of acute renal failure and cardiac complication.

Ferrotoxicity and its amelioration by endogenous vitamin D in experimental acute kidney injury

Acute kidney injury causes significant morbidity and mortality. This experimental animal study investigated the simultaneous impact of iron and vitamin D on acute kidney injury induced by iohexol, an iodinated, non-ionic monomeric radiocontrast agent in Wistar rats. Out of 36 healthy male Wistar rats, saline was injected into six control rats (group 1) and iohexol into the remaining 30 experimental rats (groups 2 to 6 comprising six rats each). Biochemical, renal histological changes, and gene expression of iron-regulating proteins and 1 α-hydroxylase were analyzed. Urinary neutrophil gelatinase-associated lipocalin (NGAL), serum creatinine, urine protein, serum and urine catalytic iron, 25-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3, and tissue lipid peroxidation were assayed. Rats injected with iohexol showed elevated urinary NGAL (11.94 ± 6.79 ng/mL), serum creatinine (2.92 ± 0.91 mg/dL), and urinary protein levels (11.03 ± 9.68 mg/mg creatinine) together with histological evidence of tubular injury and iron accumulation. Gene expression of iron-regulating proteins and 1 α-hydroxylase was altered. Serum and urine catalytic iron levels were elevated (0.57 ± 0.17; 48.95 ± 29.13 µmol/L) compared to controls (0.49 ± 0.04; 20.7 ± 2.62 µmol/L, P < 0.001). Urine catalytic iron positively correlated with tissue peroxidation (r = 0.469, CI 0.122 to 0.667, P = 0.004) and urinary NGAL (r = 0.788, CI 0.620 to 0.887, P < 0.001). 25-hydroxyvitamin D3 (61.58 ± 9.60 ng/mL) and 1,25-dihydroxyvitamin D3 (50.44 ± 19.76 pg/mL) levels increased simultaneously. In a multivariate linear regression analysis, serum iron, urine catalytic iron, and tissue lipid peroxidation independently and positively predicted urinary NGAL, an acute kidney injury biomarker. This study highlights the nephrotoxic potential of catalytic iron besides demonstrating a concurrent induction of vitamin D endogenously for possible renoprotection in acute kidney injury.

Impact statement

This work provides in-depth insights on catalytic iron-induced cytotoxicity and the resultant triggering of endogenous vitamin D synthesis in experimental acute kidney injury. Our results reveal significantly elevated levels of catalytic iron culminating in oxidant-mediated renal injury and a concomitant increase in 1,25-dihdyroxyvitamin D3 levels. Also, changes in other iron-related proteins including transferrin, ferritin, and hepcidin were observed both in the serum as well as in their mRNA expression. We consider all these findings vital since no connection between catalytic iron and vitamin D has been established so far. Furthermore, we believe that this work provides new and interesting results, with catalytic iron emerging as an important target in ameliorating renal cellular injury, possibly by timely administration of vitamin D. It also needs to be seen if these observations made in rats could be translated to humans by means of robust clinical trials.

B Lymphocyte-Derived CCL7 Augments Neutrophil and Monocyte Recruitment, Exacerbating Acute Kidney Injury

AKI is a serious condition affecting one fifth of hospital patients.

In AKI, B cells produce CCL7 and facilitate neutrophil and monocyte recruitment.

CCL7 blockade in mice reduces myeloid cell infiltration and ameliorates AKI.

Acute kidney injury (AKI) is a serious condition affecting one fifth of hospital inpatients. B lymphocytes have immunological functions beyond Ab production and may produce cytokines and chemokines that modulate inflammation. In this study, we investigated leukocyte responses in a mouse model of AKI and observed an increase in circulating and kidney B cells, particularly a B220^low subset, following AKI. We found that B cells produce the chemokine CCL7, with the potential to facilitate neutrophil and monocyte recruitment to the injured kidney. Siglec-G–deficient mice, which have increased numbers of B220^low innate B cells and a lower B cell activation threshold, had increased Ccl7 transcripts, increased neutrophil and monocyte numbers in the kidney, and more severe AKI. CCL7 blockade in mice reduced myeloid cell infiltration into the kidney and ameliorated AKI. In two independent cohorts of human patients with AKI, we observed significantly higher CCL7 transcripts compared with controls, and in a third cohort, we observed an increase in urinary CCL7 levels in AKI, supporting the clinical importance of this pathway. Together, our data suggest that B cells contribute to early sterile inflammation in AKI via the production of leukocyte-recruiting chemokines.

Evaluation of renal ischemia-reperfusion injury by magnetic resonance imaging texture analysis: An experimental study

PURPOSE

To explore the value of MRI texture analysis in evaluating the presence and severity of early renal ischemia-reperfusion injury (IRI).

METHODS

Healthy New Zealand rabbits were used (IRI group, N = 54; control group, N = 8). Rabbits in the IRI group underwent left renal artery clamping for 60 minutes. Magnetic resonance imaging was performed before and at 1, 12, 24, and 48 hours after IRI. The relationship between MRI texture features and histopathology parameters was assessed using Pearson's correlation coefficients. The diagnostic performance of texture features in kidney differentiation at different time points was assessed by receiver operating characteristic curve analysis.

RESULTS

T₂ WI_S(3,-3)Inverse_Difference_Moment had the strongest correlation with brush border destruction, tubular epithelial edema, necrosis, and cast (r = 0.56, -0.58, 0.62, and 0.69, respectively; all P < .001). BOLD_S(4,-4)Correlation had the strongest correlation with interstitial inflammatory cell infiltration (r = 0.63, P < .001). SWI_S(4,4)Difference_Entropy had the strongest correlation with microvessel density (r = 0.61, P < .001). The areas under the curve for T₂ WI_S(3,-3)Inverse_Difference_Moment, SWI_S(4,4)Difference_Entropy, and BOLD_S(4,-4)Correlation in kidney differentiation before IRI and that at 1 and 12 hours after reperfusion were 0.76, 0.72, and 0.70, respectively; the values before IRI and at 24 and 48 hours after reperfusion were 0.84, 0.81, and 0.69, respectively. The area under the curve for T₂ WI_S(3,-3)Inverse_Difference_Moment in kidney differentiation at 1 and 12 hours after reperfusion and that at 24 and 48 hours after reperfusion was 0.66.

CONCLUSION

Magnetic resonance imaging texture analysis can be used for evaluating the presence and severity of early renal IRI.

Acute Kidney Injury in Active Wars and Other Man-Made Disasters

Acute kidney injury (AKI) is frequent during wars and other man-made disasters, and contributes significantly to the overall death toll. War-related AKI may develop as a result of polytrauma, traumatic bleeding and hypovolemia, chemical and airborne toxin exposure, and crush syndrome. Thus, prerenal, intrinsic renal, or postrenal AKI may develop at the battlefield, in field hospitals, or tertiary care centers, resulting not only from traumatic, but also nontraumatic, etiologies. The prognosis usually is unfavorable because of systemic and polytrauma-related complications and suboptimal therapeutic interventions. Measures for decreasing the risk of AKI include making preparations for foreseeable disasters, and early management of polytrauma-related complications, hypovolemia, and other pathogenetic mechanisms. Transporting casualties initially to field hospitals, and afterward to higher-level health care facilities at the earliest convenience, is critical. Other man-made disasters also may cause AKI; however, the number of patients is mostly lower and treatment possibilities are broader than in war. If there is no alternative other than prolonged field care, the medical community must be prepared to offer health care and even perform dialysis in austere conditions, which in that case, is the only option to decrease the death toll resulting from AKI.

Renal ischemia/reperfusion injury: An insight on in vitro and in vivo models

Optimal tissue oxygenation is essential for its normal function. Suboptimal oxygenation or ischemia contributes to increased mortalities during various pathological conditions such as stroke, acute kidney injury (AKI), cardiac failure. Despite the rapid progression of renal tissue injury, the mechanism underlying renal ischemia/reperfusion injury (IRI) remains highly unclear. Experimental in vitro and in vivo models epitomizing the fundamental process is critical to the research of the pathogenesis of IRI and the development of plausible therapeutics. In this review, we describe the in vitro and in vivo models of IRI, ranges from proximal tubular cell lines to surgery-based animal models like clamping of both renal pedicles (bilateral IRI), clamping of one renal pedicle (unilateral IRI), clamping of one/or both renal arteries/or vein, or unilateral IRI with contralateral nephrectomy (uIRIx). Also, advanced technologies like three-dimensional kidney organoids, kidney-on-a-chip are explained. This review provides thoughtful information for establishing reliable and pertinent models for studying IRI-associated acute renal pathologies.

Current Concepts on the Reno-Protective Effects of Phosphodiesterase 5 Inhibitors in Acute Kidney Injury: Systematic Search and Review

Acute kidney injury (AKI) is associated with increased morbidity, prolonged hospitalization, and mortality, especially in high risk patients. Phosphodiesterase 5 inhibitors (PDE5Is), currently available as first-line therapy of erectile dysfunction in humans, have shown a beneficial potential of reno-protection through various reno-protective mechanisms. The aim of this work is to provide a comprehensive overview of the available literature on the reno-protective properties of PDE5Is in the various forms of AKI. Medline was systematically searched from 1946 to November 2019 to detect all relevant animal and human studies in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. In total, 83 studies were included for qualitative synthesis. Sildenafil is the most widely investigated compound (42 studies), followed by tadalafil (20 studies), icariin (10 studies), vardenafil (7 studies), zaprinast (4 studies), and udenafil (2 studies). Even though data are limited, especially in humans with inconclusive or negative results of only two clinically relevant studies available at present, the results of animal studies are promising. The reno-protective action of PDE5Is was evident in the vast majority of studies, independently of the AKI type and the agent applied. PDE5Is appear to improve the renal functional/histopathological alternations of AKI through various mechanisms, mainly by affecting regional hemodynamics, cell expression, and mitochondrial response to oxidative stress and inflammation.

Renoprotective effect of irbesartan in a rat model of gentamicin-induced nephrotoxicity: Role of oxidative stress

BACKGROUND:

The renin–angiotensin system (RAS) is essential in renal physiology; however, disturbance of the RAS is one of the chief pathways involved in renal injury. Dysregulation of RAS may result in both glomerular and tubulointerstitial injuries through direct effects of angiotensin II (Ang II) type 1 receptor. Irbesartan and other Ang II blockers have renoprotective effect through reduction of on renal inflammations. Therefore, the aim of the present study was to demonstrate the renoprotective effect of irbesartan on gentamicin-induced nephrotoxicity in rats concerning the oxidative stress.

MATERIALS AND METHODS:

Thirty Sprague-Dawley Male rats divided into three groups, Group I (10 rats) treated with distilled water, Group II (10 rats) treated with gentamicin, and Group III (10 rats) treated with gentamicin plus irbesartan for 12 days. Blood urea, serum creatinine, serum malondialdehyde (MDA), superoxide dismutase (SOD), glutathione reductase (GSH), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecules (KIM-1), and cystatin-c were measured in each group.

RESULTS:

Irbesartan significantly reduced blood urea, serum creatinine, serum MDA, NGAL, KIM-1, and cystatin-c P < 0.05. Irbesartan significantly increases SOD P < 0.05 without significant effect in elevation of GSH serum levels.

CONCLUSION:

Irbesartan has renoprotective effect in attenuation of acute nephrotoxicity through modulation of oxidative stress and antioxidant capacity in rats.

Nephroprotective Role of Selenium Nanoparticles Against Glycerol-Induced Acute Kidney Injury in Rats

Acute kidney injury (AKI) is a clinical syndrome associated with the incidence of rhabdomyolysis (RM). The current study was carried out to evaluate whether selenium nanoparticles (SeNPs) can protect against the glycerol-induced AKI model. Rats were distributed into four equal groups (n = 7): the control group (G1), SeNPs group (G2), AKI group (G3), and SeNPs+AKI group (G4). Rats in G1 were intramuscularly injected with physiological saline (0.9% NaCl). Rats in G2 were gavaged with SeNPs (0.1 mg/kg) for 14 days. Rats in G3 were intramuscularly injected with 50% glycerol (10 ml/kg). Rats in G4 were administered with SeNPs for 14 days and then injected with glycerol, as in G3. Glycerol-injected rats showed a significant increase in the kidney relative weight, as well as in the serum urea, creatinine, Kim-1, and renal malondialdehyde, nitric oxide, TNF-α, IL-1β, cytochrome c, Bax, and caspase-3 levels. In addition, a significant decrease in glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase was recorded in the renal tissue. Selenium nanoparticles reduced the biochemical, molecular, and histological changes produced by glycerol. Overall, our results suggest that selenium nanoparticles could be used to protect against AKI development via antioxidant, anti-inflammatory, and anti-apoptotic activities.

Twelve previously healthy non-geriatric dogs present for acute kidney injury after general anaesthesia for non-emergency surgical procedures in the UK

OBJECTIVES

To characterise common factors after a suspected increase in the incidence of post-procedure acute kidney injury in healthy dogs presenting for non-emergency surgical procedures.

MATERIALS AND METHODS

Retrospective analysis of the medical records of 12 dogs that presented for acute kidney injury after general anaesthesia for non-emergency surgical procedures.

RESULTS

The 12 non-geriatric dogs re-presented with acute kidney injury at a median of 4 days after surgery to four different veterinary centres, including three multidisciplinary referral practices in the UK. All dogs in this case series weighed more than 20 kg and had a median age of 17 months. There was no apparent association with breed, type of surgery, duration of anaesthesia, perioperative drug choice or non-steroidal anti-inflammatory drug administration.

CLINICAL SIGNIFICANCE

Although well-defined in human medicine, there is very little information regarding the association between general anaesthesia and acute kidney injury in animals. No definitive causal link was found in this case series. Clinicians with similar cases are requested to contact the corresponding author so a more representative incidence rate can be obtained.

Plasma Concentrations of Extracellular DNA in Acute Kidney Injury

Current diagnostic methods of acute kidney injury (AKI) have limited sensitivity and specificity. Tissue injury has been linked to an increase in the concentrations of extracellular DNA (ecDNA) in plasma. A rapid turnover of ecDNA in the circulation makes it a potential marker with high sensitivity. This study aimed to analyze the concentration of ecDNA in plasma in animal models of AKI. Three different fractions of ecDNA were measured—total ecDNA was assessed fluorometrically, while nuclear ecDNA (ncDNA) and mitochondrial DNA (mtDNA) were analyzed using quantitative real-time PCR. AKI was induced using four different murine models of AKI-bilateral ureteral obstruction (BUO), glycerol-induced AKI (GLY), ischemia–reperfusion injury (IRI) and bilateral nephrectomy (BNx). Total ecDNA was significantly higher in BUO (p < 0.05) and GLY (p < 0.05) compared to the respective control groups. ncDNA was significantly higher in BUO (p < 0.05) compared to SHAM. No significant differences in the concentrations of mtDNA were found between the groups. The plasma concentrations of different fractions of ecDNA are dependent on the mechanism of induction of AKI and warrant further investigation as potential surrogate markers of AKI.

Renal protective effect of nebivolol in rat models of acute renal injury: role of sodium glucose co-transporter 2

BACKGROUND

Upregulation of the sodium glucose co-transporter (SGLT2) is implicated in acute renal injury (ARI) progression and is regulated by extracellular signal-regulated kinase (ERK), hypoxia-inducible factor 1 alpha (HIF1α) or prostaglandin E2 (PGE2). This study aimed to assess the possible protective effect of nebivolol on renal ischemia/reperfusion (IR) and glycerol-induced ARI targeting SGLT2 via modulating the ERK-HIF1α pathway.

METHODS

Rats were divided into control, sham, IR or nebivolol-treated group, in which rats were treated with nebivolol (10 mg/kg) for 3 days prior to the induction of IR. The rats were subjected to renal ischemia by bilateral clamping of the pedicles for 45 min, followed by 24 h reperfusion. Another group of rats received the vehicle or nebivolol (10 mg/kg) for 3 days followed by injection of 50% glycerol (8 ml/kg, IM) or saline. Kidney function tests, systolic blood pressure (SBP), oxidative stress markers [malondialdehyde (MDA) and NADPH oxidase] and kidney levels of nitric oxide (NO), inducible nitric oxide synthase (iNOS), HIF1α, ERK phosphorylation and PGE2 were determined. Additionally, renal sections were used for histological grading of renal injury and immunological expression of SGLT2.

RESULTS

ARI rats showed significantly increased SBP, poor kidney function tests, increased oxidative stress, iNOS, NO, HIF1α levels, decreased PGE2 and ERK phosphorylation and upregulation of SGLT2 expression. Nebivolol treatment protected against the kidney damage both on the biochemical and histological levels.

CONCLUSION

Nebivolol has a direct renoprotective effect, at least in part, by down-regulating SGLT2 possibly via modulating HIF1α, ERK activity and PGE2 production.

Irbesartan Attenuates Gentamicin-induced Nephrotoxicity in Rats through Modulation of Oxidative Stress and Endogenous Antioxidant Capacity

Background:

Overproduction of reactive oxygen species and free radicals is the main mechanism beyond gentamicin-induced nephrotoxicity. Irbesartan and other angiotensin II blockers offer significant nephroprotective effect through improvement of renal function and reduction of renal inflammation. Therefore, the objective of this study was to illustrate the nephroprotective effect of irbesartan in rats regarding the oxidative stress of irbesartan biomarkers.

Methods:

Thirty male Sprague–Dawley rats were used; they were divided into three groups: Group I (10 rats) treated with distilled water, Group II (10 rats) treated with gentamicin, and Group III (10 rats) treated with gentamicin plus irbesartan for 12 days. Blood urea, serum creatinine, serum malondialdehyde (MDA), superoxide dismutase (SOD), glutathione reductase (GSH), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule (KIM-1), and cystatin-c were measured in each group.

Results:

Irbesartan significantly reduced blood urea, serum creatinine, serum MDA, NGAL, KIM-1, and cystatin-c [P < 0.05]. Irbesartan significantly increases SOD [P < 0.05] without significant effect in elevation of GSH serum levels.

Conclusions:

This study concluded that irbesartan has a nephroprotective effect in attenuation of acute nephrotoxicity through modulation of oxidative stress and antioxidant capacity in rats.

Treating Acute Kidney Injury with Antioxidative Black Phosphorus Nanosheets

Black phosphorus nanosheets (BPNSs) have been actively employed as nanomedicine agents for photothermal and photodynamic therapy by virtue of their unique optical properties. However, their chemical reactivity as a competent biomaterial has not been fully explored yet. Here, we report on the use of BPNSs as reactive oxygen species (ROS) scavengers to cure acute kidney injury (AKI) in mice. Importantly, in vivo analysis in mice revealed that BPNSs were preferably accumulated in kidney. We found that BPNSs alleviated oxidative-pressure-induced cellular apoptosis. In a ROS-triggered acute kidney injury (AKI) model, BPNSs effectively consumed ROS in kidney, demonstrating high efficacy for curing AKI. BPNSs also exhibited excellent biocompatibility and biodegradability, making them promising candidates for therapeutic treatment of AKI and other renal diseases.

Punica granatum improves renal function in gentamicin-induced nephropathy in rats via attenuation of oxidative stress

BACKGROUND

Gentamicin is widely used as an antibiotic for the treatment of gram negative infections. Evidences indicates that oxidative stress is involved in gentamicin-induced nephrotoxicity. In Ayurvedic medicine, Punica granatum Linn. is considered as 'a pharmacy unto itself". It has been claimed in traditional literature, to treat various kidney ailments due to its antioxidant potential.

OBJECTIVE

To explore the possible mechanism of action of methanolic extract of P.granatum leaves (MPGL) in exerting a protective effect on gentamicin-induced nephropathy.

MATERIAL AND METHODS

Animals were administered with gentamicin (80 mg/kg/day i.m.) and simultaneously with MPGL (100, 200 and 400 mg/kg p.o.) or metformin (100 mg/kg p.o.) for 8 days. A satellite group was employed in order to check for reversibility of nephrotoxic effects post discontinuation of gentamicin administration. At the end of the study, all the rats were sacrificed and serum-urine parameters were investigated. Antioxidant enzymes and tumor necrosis factor alpha (TNF-α) levels were determined in the kidney tissues along with histopathological examination of kidneys.

RESULTS

Increase in serum creatinine, urea, TNF-α, lipid peroxidation along with fall in the antioxidant enzymes activity and degeneration of tubules, arterioles as revealed by histopathological examination confirmed the manifestation of nephrotoxicity caused due to gentamicin. Simultaneous administration of MPGL and gentamicin protected kidneys against nephrotoxic effects of gentamicin as evidenced from normalization of renal function parameters and amelioration of histopathological changes.

CONCLUSION

Data suggests that MPGL attenuated oxidative stress associated renal injury by preserving antioxidant enzymes, reducing lipid peroxidation and inhibiting inflammatory mediators such as TNF-α.

Notch Signaling in Kidney Development, Maintenance, and Disease

Kidney development involves formation of nephrons intricately aligned with the vasculature and connected to a branched network of collecting ducts. Notch signaling plays multiple roles during kidney development involving the formation of nephrons composed of diverse epithelial cell types arranged into tubular segments, all the while maintaining a nephron progenitor niche. Here, we review the roles of Notch signaling identified from rodent kidney development and injury studies, while discussing human kidney diseases associated with aberrant Notch signaling. We also review Notch signaling requirement in maintenance of mature kidney epithelial cell states and speculate that Notch activity regulation mediates certain renal physiologic adaptations.

Capillary rarefaction is more closely associated with CKD progression after cisplatin, rhabdomyolysis, and ischemia-reperfusion-induced AKI than renal fibrosis

Acute kidney injury (AKI) is a strong independent predictor of mortality and often results in incomplete recovery of renal function, leading to progressive chronic kidney disease (CKD). Many clinical trials have been conducted on the basis of promising preclinical data, but no therapeutic interventions have been shown to improve long-term outcomes after AKI. This is partly due to the failure of preclinical studies to accurately model clinically relevant injury and long-term outcomes on CKD progression. Here, we evaluated the long-term effects of AKI on CKD progression in three animal models reflecting diverse etiologies of AKI: repeat-dose cisplatin, rhabdomyolysis, and ischemia-reperfusion injury. Using transdermal measurement of glomerular filtration rate as a clinically relevant measure of kidney function and quantification of peritubular capillary density to measure capillary rarefaction, we showed that repeat-dose cisplatin caused capillary rarefaction and decreased renal function in mice without a significant increase in interstitial fibrosis, whereas rhabdomyolysis-induced AKI led to severe interstitial fibrosis, but renal function and peritubular capillary density were preserved. Furthermore, long-term experiments in mice with unilateral ischemia-reperfusion injury showed that restoration of renal function 12 wk after a contralateral nephrectomy was associated with increasing fibrosis, but a reversal of capillary rarefaction was seen at 4 wk. These data demonstrate that clear dissociation between kidney function and fibrosis in these models of AKI to CKD progression and suggest that peritubular capillary rarefaction is more strongly associated with CKD progression than renal fibrosis.

Comparison of olive leaf, olive oil, palm oil, and omega-3 oil in acute kidney injury induced by sepsis in rats

Background

Hypotension, increased production of reactive oxygen species, and inflammation are all observed in experimental models of sepsis induced by lipopolysaccharide (LPS).

Purpose

The aim of this study was to evaluate the effects of an ethanolic extract of Brazilian olive leaf (Ex), Brazilian olive oil (Olv), Ex + Olv (ExOlv), and palm oil (Pal) in comparison to the effects of omega-3 fish oil (Omg) in a rat model of sepsis-induced acute kidney injury.

Materials

Wistar rats were divided into seven groups (seven per group), which were either untreated (control) or treated with LPS, LPS + Ex, LPS + ExOlv, LPS + Olv, LPS + Omg, or LPS + Pal.

Results

Lower values of creatinine clearance and blood pressure were observed in the LPS-treated group, and these values were not affected by Ex, Olv, ExOlv, Pal, or Omg treatment. Mortality rates were significantly lower in rats exposed to LPS when they were also treated with Ex, ExOlv, Olv, Pal, or Omg. These treatments also decreased oxidative stress and inflammation (Tumor necrosis factor alpha, interleukin-1 beta) and increased interleukin-10 levels and cell proliferation, which were associated with decreased apoptosis in kidney tissue.

Conclusion

Ex and Pal treatments were beneficial in septic rats, since they increased survival rate and did not aggravate inflammation. However, the most effective treatments for septic rats were Olv in comparison to Omg. These natural food substances could enable the development of effective therapeutic interventions to sepsis.

Effect of Ocimum basilicum leaves extract on acetaminophen-induced nephrotoxicity in BALB/c mice

Background

Acetaminophen (APAP) is one of the most widely used drugs to treat pain. Its overdose is lethal causing liver and kidney failure. Nephrotoxicity and hepatotoxicity are mostly due to the overproduction of reactive oxygen species. Ocimum basilicum, known as basil, is a commonly used medicinal plant due to its versatile role as antibacterial, antifungal, and anti-oxidative. We aim in this study to investigate the preventive and protective effect of basil leaves aqueous extract against APAP-induced hepatorenal toxicity in BALB/c mice.

Methods

Acute kidney injury (AKI) was induced in mice using APAP. Mice were treated with basils extract pre and post AKI induction. Kidney and liver functions were assessed by measuring creatinine, urea, alanine transaminase, and aspartate transaminase levels in serum. Superoxide dismutase, catalase (CAT), and malondialdehyde levels of renal and hepatic tissues were assayed using Elisa. Kidney injury molecule (KIM-1) was quantified in kidney homogenate. Histopathological analysis of kidney and liver were examined.

Results

Significant increase in all serum parameters, in hepatic and renal MDA, and in renal KIM-1 levels was observed post AKI induction. Treatment with basils post AKI induction minimized APAP damage by reducing serum markers and MDA in both organs and by increasing SOD and CAT. However, pretreatment with basils extract caused additional increase in serum ALT and AST and MDA in liver, with a significant increase in renal antioxidant enzymes. These results were confirmed by histopathological examination.

Conclusion

Basil extract may act as a natural antioxidant to treat APAP-induced acute hepato-renal toxicity when used as a post-treatment.

Is it possible to prevent contrast-induced nephropathy with dexpanthenol?

PURPOSE

Contrast-induced nephropathy (CIN) is one of the side effects of diagnostic procedures. Oxidative stress plays an important role in CIN's pathophysiology. Dexpanthenol (Dexp) is a substance with antioxidant efficacy. We investigated the likely protective effects of dexpanthenol for CIN.

METHODS

Twenty-four Sprague-Dawley rats were divided randomly into four groups of 6 rats; control (group 1), Dexp (group 2), CIN (group 3) and Dexp + CIN (group 4). All rats were restricted of water moderately to facilitate of nephrotoxicity. Dexp was administered into the intraperitoneally at a dose of 500 mg/kg for 5 days in groups 2 and 4. The same amount of saline was applied via intraperitoneally to group 1 and 3. In CIN and Dexp + CIN groups, L-NAME (10 mg/kg), tenoxicam (0.5 mg/kg) and sodium amidotrizoate (10 ml/kg) were administered on the 4th day via the tail vein for CIN. All rats were euthanized on the 6th day and samples for biochemical and pathological evaluations were collected.

RESULTS

When the Dexp + CIN group and the CIN group were compared, it was found to be provide a significant decline at the level of acute tubular injury and necrosis in kidney biopsies by dexp. Furthermore Dexp significantly reduced the serum cystatin C (Cys-C) levels, not serum creatinine. There was no statistically significant difference between the groups in total oxidant and antioxidant levels.

CONCLUSIONS

Dexpanthenol did not have significant effect on oxidative stress of acute kidney injury on this rat model. However, it has ameliorated serum Cys-C levels and histopathological findings of CIN.

Bioelectronic Approaches to Control Neuroimmune Interactions in Acute Kidney Injury

Recent studies have shown renal protective effects of bioelectric approaches, including ultrasound treatment, electrical vagus nerve stimulation, and optogenetic brainstem C1 neuron stimulation. The renal protection acquired by all three modalities was lost in splenectomized mice and/or α7 subunit of the nicotinic acetylcholine receptor-deficient mice. C1 neuron-mediated renal protection was blocked by β2-adrenergic receptor antagonist. These findings indicate that all three methods commonly, at least partially, activate the cholinergic anti-inflammatory pathway, a well-studied neuroimmune pathway. In this article, we summarize the current understanding of neuroimmune axis-mediated kidney protection in preclinical models of acute kidney injury by these three modalities. Examination of the differences among these three modalities might lead to a further elucidation of the neuroimmune axis involved in renal protection and is of interest for developing new therapeutic approaches.

Hemogram and iron indices in renal anemia and the amelioration with Carica papaya leaf extract applied on albino rat model

The present study was designed to look at the hematological disorders in gentamicin nephrotoxicity model, as kidney is considered as one of the hemopoietic organs. In a previous study, novel and classical kidney injury biomarkers were utilized to evaluate the nephroprotective potential of Carica papaya leaf extract (CPLE) in the same model in albino rats. Gentamicin (100 mg/kg, subcutaneously, for 21 consecutive days) resulted in significant decreases in red blood cell (RBC) count, hemoglobin concentration (HGB), and packed cell volume (PCV) value, with minimal alterations in erythrocytic indices. Leucogram showed leukocytosis, granulocytosis, and thrombocytopenia. Erythropoietin (EPO) levels were also drastically decreased by the end of the experimental course. Serum iron, unsaturated iron-binding capacity (UIBC), total iron binding capacity (TIBC), transferrin saturation %, and serum transferrin concentration values were significantly decreased in contrast to ferritin, which was increased. When concurrently administered with gentamicin, CPLE (150 and 300 mg/kg, orally via gastric tube, for 21 days) significantly protected against the drastic effects of the former on the blood profile with improving potentials on erythrogram, leukogram, thrombocytes, EPO, iron and its indices, in a dose-dependent manner. These data may suggest CPLE as an appreciated blood homeostatic and nephroprotective agent from a natural source that could be a good remedy in conditions associated with blood disorders.

Group 2 Innate Lymphoid Cells Are Redundant in Experimental Renal Ischemia-Reperfusion Injury

Acute kidney injury (AKI) can be fatal and is a well-defined risk factor for the development of chronic kidney disease. Group 2 innate lymphoid cells (ILC2s) are innate producers of type-2 cytokines and are critical regulators of homeostasis in peripheral organs. However, our knowledge of their function in the kidney is relatively limited. Recent evidence suggests that increasing ILC2 numbers by systemic administration of recombinant interleukin (IL)-25 or IL-33 protects against renal injury. Whilst ILC2s can be induced to protect against ischemic- or chemical-induced AKI, the impact of ILC2 deficiency or depletion on the severity of renal injury is unknown. Firstly, the phenotype and location of ILC2s in the kidney was assessed under homeostatic conditions. Kidney ILC2s constitutively expressed high levels of IL-5 and were located in close proximity to the renal vasculature. To test the functional role of ILC2s in the kidney, an experimental model of renal ischemia-reperfusion injury (IRI) was used and the severity of injury was assessed in wild-type, ILC2-reduced, ILC2-deficient, and ILC2-depleted mice. Surprisingly, there were no differences in histopathology, collagen deposition or mRNA expression of injury-associated (Lcn2), inflammatory (Cxcl1, Cxcl2, and Tnf) or extracellular matrix (Col1a1, Fn1) factors following IRI in the absence of ILC2s. These data suggest the absence of ILC2s does not alter the severity of renal injury, suggesting possible redundancy. Therefore, other mechanisms of type 2-mediated immune cell activation likely compensate in the absence of ILC2s. Hence, a loss of ILC2s is unlikely to increase susceptibility to, or severity of AKI.

The role of podocyte damage in the etiology of ischemia-reperfusion acute kidney injury and post-injury fibrosis

Background

To establish a model of chronic renal fibrosis following acute kidney injury (AKI) in BALB/c mice and to observe the effect of AKI on podocyte injury and chronic fibrosis of the kidney. Additional aims included using the model to explore the role of podocyte injury in AKI and post-injury fibrosis.

Methods

Fifty BALB/C mice were randomly divided into control group (Ctr), sham group (sham), AKI 20 group (renal ischemia, 20 min reperfusion), AKI 30 group (renal ischemia, 30 min reperfusion) and AKI 40 group (renal ischemia, 40 min reperfusion). Mice serum and 24-h urine were collected on the 8th, 9th, 10th, 14th, and 28th days for urinary protein, serum creatinine (Scr) and blood urea nitrogen (BUN) analysis. HE staining, transmission electron microscopy (TEM), Masson staining, Q-PCR, Western Blot and immunohistochemistry were applied.

Results

Serum Scr and BUN levels across all AKI groups at the 9th day were significantly higher (P < 0.05) than controls, with higher reperfusion groups maintaining that increase up to 28 days (P < 0.05). Compared with Ctr group, the urinary protein of the AKI 40 group significantly rose on the 9th day (P < 0.05), normalizing immediately on the 10th day (P < 0.05). In contrast, the AKI 30 group rose significantly on the 14th day (P < 0.05) maintaining elevated levels for two weeks (P < 0.05). HE staining demonstrated ischemia-dependent renal tissue damage was aggravated in the mild to aggravated AKI groups. Mesangial proliferation, glomerulosclerosis, and tubulointerstitial pathology were also significantly increased in these groups (P < 0.05). Masson staining further showed that glomerular, renal tubular, and interstitial collagen were increased by ischemia in a time-dependent manner. Transmission EM additionally that podocytes of the mild to severe AKI groups displayed extensive fusion, exfoliation and GBM exposure. Synaptopodin, Nephrin, and CD2AP mRNA and protein expression demonstrated ischemic time-dependent decreases, while the TRPC6 was increased. There was a significant difference in the levels of Synaptopodin, Nephrin, CD2AP, and TRPC6 between the mild and severe AKI groups (P < 0.05).

Conclusions

1) During the AKI process mice podocyte injury, proteinuria and the subsequent progression into chronic renal fibrosis is observed.2) Podocyte injury may be one of the causes of ischemia-reperfusion acute kidney injury and post-injury fibrosis.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1298-x) contains supplementary material, which is available to authorized users.

Heart-kidney interactions: mechanistic insights from animal models

Pathological changes in the heart or kidney can instigate the release of a cascade of cardiorenal mediators that promote injury in the other organ. Combined dysfunction of heart and kidney is referred to as cardiorenal syndrome (CRS) and has gained considerable attention. CRS has been classified into five distinct entities, each with different major pathophysiological changes. Despite the magnitude of the public health problem of CRS, the underlying mechanisms are incompletely understood, and effective intervention is unavailable. Animal models have allowed us to discover pathogenic molecular changes to clarify the pathophysiological mechanisms responsible for heart-kidney interactions and to enable more accurate risk stratification and effective intervention. Here, this article focuses on the use of currently available animal models to elucidate mechanistic insights in the clinical cardiorenal phenotype arising from primary cardiac injury, primary renal disease with special emphasis of chronic kidney disease-specific risk factors, and simultaneous cardiorenal/renocardiac dysfunction. The development of novel animal models that recapitulate more closely the cardiorenal phenotype in a clinical scenario and discover the molecular basis of this condition will be of great benefit.

Emerging therapeutic potential of group 2 innate lymphoid cells in acute kidney injury

Acute kidney injury (AKI) remains a global challenge and, despite the availability of dialysis and transplantation, can be fatal. Those that survive an AKI are at increased risk of developing chronic kidney disease and end stage renal failure. Understanding the fundamental mechanisms underpinning the pathophysiology of AKI is critical for developing novel strategies for diagnosis and treatment. A growing body of evidence indicates that amplifying type 2 immunity may have therapeutic potential in kidney injury and disease. Of particular interest are the recently described subset of innate immune cells, termed group 2 innate lymphoid cells (ILCs). Group 2 ILCs are crucial tissue-resident immune cells that maintain homeostasis and regulate tissue repair at multiple organ sites, including the kidney. They are critical mediators of type 2 immune responses following infection and injury. The existing literature suggests that activation of group 2 ILCs and production of a local type 2 immune milieu is protective against renal injury and associated pathology. In this review, we describe the emerging role for group 2 ILCs in renal homeostasis and repair. We provide an in-depth discussion of the most recent literature that use preclinical models of AKI and assess the therapeutic effect of modulating group 2 ILC function. We debate the potential for targeting these cells as novel cellular therapies in AKI and discuss the implications for future studies and translation. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Renal globotriaosylceramide facilitates tubular albumin absorption and its inhibition protects against acute kidney injury

To elucidate the physiologic function of renal globotriaosylceramide (Gb3/CD77), which up-to-date has been associated exclusively with Shiga toxin binding, we have analyzed renal function in Gb3-deficient mice. Gb3 synthase KO (Gb3S^-/-) mice displayed an increased renal albumin and low molecular weight protein excretion compared to WT. Gb3 localized at the brush border and within vesicular structures in WT proximal tubules and has now been shown to be closely associated with the receptor complex megalin/cubilin and with albumin uptake. In two clinically relevant mouse models of acute kidney injury caused by myoglobin as seen in rhabdomyolysis and the aminoglycoside gentamicin, Gb3S^-/- mice showed a preserved renal function and morphology, compared to WT. Pharmacologic inhibition of glucosylceramide-based glycosphingolipids, including Gb3, in WT mice corroborated the results of genetically Gb3-deficient mice. In conclusion, our data significantly advance the current knowledge on the physiologic and pathophysiologic role of Gb3 in proximal tubules, showing an involvement in the reabsorption of filtered albumin, myoglobin and the aminoglycoside gentamicin.

Protective effects of N-acetyl-cysteine in mitochondria bioenergetics, oxidative stress, dynamics and S-glutathionylation alterations in acute kidney damage induced by folic acid

Folic acid (FA)-induced acute kidney injury (AKI) is a widely used model for studies of the renal damage and its progression to chronic state. However, the molecular mechanisms by which FA induces AKI remain poorly understood. Since renal function depends on mitochondrial homeostasis, it has been suggested that mitochondrial alterations contribute to AKI development. Additionally, N-acetyl-cysteine (NAC) can be a protective agent to prevent mitochondrial and renal dysfunction in this model, given its ability to increase mitochondrial glutathione (GSH) and to control the S-glutathionylation levels, a reversible post-translational modification that has emerged as a mechanism able to link mitochondrial energy metabolism and redox homeostasis. However, this hypothesis has not been explored. The present study demonstrates for the first time that, at 24 h, FA induced mitochondrial bioenergetics, redox state, dynamics and mitophagy alterations, which are involved in the mechanisms responsible for the AKI development. On the other hand, NAC preadministration was able to prevent mitochondrial bioenergetics, redox state and dynamics alterations as well as renal damage. The protective effects of NAC on mitochondria and renal function could be related to its observed capacity to preserve the S-glutathionylation process and GSH levels in mitochondria. Taken together, our results support the idea that these mitochondrial processes can be targets for the prevention of the renal damage and its progression in FA-induced AKI model.

Synergistic effect of berberine and pentoxifylline in attenuation of acute kidney injury

Objective

To evaluate the renoprotective effects of berberine and/or pentoxifylline in reduction of diclofenac-induced acute kidney injury (AKI) in rats.

Material and Methods

Fifty male Sprague-Dawley rats were allocated into five groups, Group 1: Rats treated with distilled water plus normal saline for 12 days. Group 2: Rats treated with distilled water plus diclofenac for 12 days. Group 3: Rats treated with berberine plus diclofenac for 12 days. Group 4: Rats treated with pentoxifylline plus diclofenac for 12 days. Group 5: Rats treated with berberine + pentoxifylline plus diclofenac 15 mg/kg for 12 days. Blood urea, creatinine, neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecules (KIM-1), and cystatin-c were used to measure the severity of AKI.

Results

Diclofenac led to significant AKI by significant elevation of blood urea, serum creatinine, KIM-1, and NGAL. Treatment with berberine showed no significant effect on all biomarkers level compared to diclofenac group except on serum KIM-1 level which also seen in the pentoxifylline group whereas combination of berberine and pentoxifylline led to more significant effect in the reduction of all renal biomarkers.

Conclusion

Combination of berberine with pentoxifylline illustrated a synergistic effect in attenuation of diclofenac-induced AKI.

Molybdenum-based nanoclusters act as antioxidants and ameliorate acute kidney injury in mice

Acute kidney injury (AKI) is a common reactive oxygen species (ROS)-related renal disease that causes numerous deaths annually, yet only supportive treatment is currently available in the clinics. Development of antioxidants with high accumulation rates in kidneys is highly desired to help prevent AKI. Here we report molybdenum-based polyoxometalate (POM) nanoclusters with preferential renal uptake as novel nano-antioxidants for kidney protection. These POM nanoclusters, with a readily variable valence state of molybdenum ions, possess the capability to scavenge detrimental ROS. Our results demonstrate that POM nanoclusters can efficiently alleviate clinical symptoms in mice subjected to AKI, as verified by dynamic PET imaging with ⁶⁸Ga-EDTA, serum tests, kidney tissue staining, and biomarkers detection in the kidneys. The protective effect of POM nanoclusters against AKI in living animals suggests exploring their use for the treatment of AKI patients, as well as patients with other ROS-related diseases.

There are currently no effective therapies available for acute kidney injury (AKI). Here the authors generate molybdenum-based polyoxometalate nanoclusters and show that these have preferential renal uptake and can ameliorate AKI pathology in mice by scavenging reactive oxygen species.

Effects of General Anesthesia on 2 Urinary Biomarkers of Kidney Injury-Hepatitis A Virus Cellular Receptor 1 and Lipocalin 2-in Male C57BL/6J Mice

Urinary biomarkers are used increasingly for sensitive prediction of kidney injury in preclinical and clinical studies. Given the frequent requirement of anesthesia in various animal models of disease, it is important to define the effects of anesthesia on kidney injury biomarkers to guide the appropriate selection of anesthetic agents and to avoid potential confounders in the interpretation of data. Therefore, we performed a prospective study using male C57BL/6J mice (n = 45) exposed to a single anesthetic episode to determine the effects several common anesthesia regimens on the urinary excretion of 2 commonly used kidney injury biomarkers: hepatitis A virus cellular receptor 1 (HAVCR1, also known as KIM1) and lipocalin 2 (LCN2, also known as NGAL). We evaluated 3 injectable regimens (ketamine-xylazine, tiletamine-zolazepam, and pentobarbital) and 2 inhalational agents (isoflurane and sevoflurane). Concentrations of HAVCR1 and LCN2 in urine collected at various time points after anesthesia were measured by using ELISA. Administration of ketamine-xylazine resulted in a significant increase in HAVCR1 levels at 6 h after anesthesia but a decrease in LCN2 levels compared with baseline. LCN2 levels steadily increased over the first 24 h after inhalant anesthesia, with a significant increase at 24 h after sevoflurane. These results suggest that injectable anesthesia had early effects on HAVCR1 and LCN2 levels, whereas inhalational agents increased these biomarkers over prolonged time.

DNA origami nanostructures can exhibit preferential renal uptake and alleviate acute kidney injury

Patients with acute kidney injury (AKI) frequently require kidney transplantation and supportive therapies, such as rehydration and dialysis. Here, we show that radiolabelled DNA origami nanostructures (DONs) with rectangular, triangular and tubular shapes accumulate preferentially in the kidneys of healthy mice and mice with rhabdomyolysis-induced AKI, and that rectangular DONs have renal-protective properties, with efficacy similar to the antioxidant N-acetylcysteine-a clinically used drug that ameliorates contrast-induced AKI and protects kidney function from nephrotoxic agents. We evaluated the biodistribution of DONs non-invasively via positron emission tomography, and the efficacy of rectangular DONs in the treatment of AKI via dynamic positron emission tomography imaging with 68Ga-EDTA, blood tests and kidney tissue staining. DNA-based nanostructures could become a source of therapeutic agents for the treatment of AKI and other renal diseases.

Protective Effects of Methane-Rich Saline on Renal Ischemic-Reperfusion Injury in a Mouse Model

BACKGROUND Renal ischemic-reperfusion (RIR) injury remains a major cause of acute kidney injury, with increased in-hospital mortality and risks for chronic kidney disease. Previous studies have proposed that oxidative stress, inflammation, and renal apoptosis are the most common causes of injury, whereas recent research proved that methane, the simplest alkane generated by an enteric microorganism or accompanying the production of reactive oxygen species (ROS), can alleviate inflammation and oxidative stress and reduce apoptosis in different organs. MATERIAL AND METHODS In the present study, we analyzed the possible effects of methane-rich saline in RIR injury in a mouse model and analyzed its possible protective effects on inflammation, oxidative stress, and apoptosis. RESULTS The results showed that treatment with methane significantly improved blood creatinine and blood urea nitrogen (BUN) levels and improved renal histology in RIR injury. Further experimentation proved that this protective effect was primarily manifested in decreased oxidative stress, less apoptosis, and reduced inflammation in renal tissues, as well as improved general responses. CONCLUSIONS Our present study proved the protective effects of methane in RIR injury and, together with previous research, confirmed the multi-organ protective effects. This may help to translate methane application and develop its use in organ ischemic-reperfusion injury.

Novel and classical renal biomarkers as evidence for the nephroprotective effect of Carica papaya leaf extract

The present study is aimed at utilization of novel and classical kidney function biomarkers to evaluate the nephroprotective potential of Carica papaya leaf extract (CPLE) in gentamicin nephrotoxicity model in albino rats. The used classical biomarkers were urea and creatinine; while the new biomarkers were Kidney injury molecule-1 (KIM-1) and Clusterin. Forty-five male albino rats were assigned into five groups and subjected to different treatments for nine consecutive days (vehicles; gentamicin, 100 mg/kg, subcutaneously; ascorbic acid, 200 mg/kg, orally; CPLE, 150 and 300 mg/kg b wt., orally). Three rats/group were killed on days 3, 6, and 9 for blood and tissue samples for renal and oxidation markers. Gentamicin resulted in significant increase in urea and creatinine only by the end of the experimental course; while the novel biomarkers were evident as early as 3 days upon gentamicin injection. When concurrently administered with gentamicin, CPLE significantly protected kidney tissues against gentamicin nephrotoxic effects indicated by decrement of both the novel and the classical standard biomarkers, in a dose-dependent manner. CPLE-mediated protection was attributed to its antioxidant potential indicated by significant inhibition of malondialdehyde (MDA) levels in both serum and kidney homogenates. The results were further supported by histopathological examination that revealed considerable amelioration of the pathological microscopic alterations induced by repeated gentamicin injection. Phytochemical analysis of CPLE indicated presence of tannins and flavonoids. These data may suggest CPLE, based on improvement of both classical and novel renal markers, as a highly potent nephroprotective and antioxidant from natural source that could be a good remedy in conditions associated with renal disorders.

CEST MRI of sepsis-induced acute kidney injury

Sepsis-induced acute kidney injury (SAKI) is a major complication of kidney disease associated with increased mortality and faster progression. Therefore, the development of imaging biomarkers to detect septic AKI is of great clinical interest. In this study, we aimed to characterize the endogenous chemical exchange saturation transfer (CEST) MRI contrast in the lipopolysaccharide (LPS)-induced SAKI mouse model and to investigate the use of CEST MRI for detecting such injury. We used a SAKI mouse model that was generated by i.p. injection of 10 mg/kg LPS. The resulting kidney injury was confirmed by the elevation of serum creatinine and histology. MRI assessments were performed 24 h after LPS injection, including CEST MRI at different B₁ strengths (1, 1.8 and 3 μT), T₁ mapping, T₂ mapping and conventional magnetization transfer contrast (MTC) MRI. The CEST MRI results were analyzed using Z-spectra, in which the normalized water signal saturation (S_sat /S₀ ) is measured as a function of saturation frequency. Substantial decreases in CEST contrast were observed at both 3.5 and - 3.5 ppm frequency offset from water at all B₁ powers, with the most significant difference obtained at a B₁ of 1.8 μT. The average S_sat /S₀ differences between injured and normal kidneys were 0.07 (0.55 ± 0.04 versus 0.62 ± 0.04, P = 0.0028) and 0.07 (0.50 ± 0.04 versus 0.57 ± 0.03, P = 0.0008) for 3.5 and - 3.5 ppm, respectively. In contrast, the T₁ and T₂ relaxation times and MTC contrast in the injured kidneys did not show a significant change compared with the normal control. Our results showed that CEST MRI is more sensitive to the pathological changes in injured kidneys than the changes in T₁ , T₂ and MTC effect, indicating its potential clinical utility for molecular imaging of renal diseases.

Artificial Liver and Renal Support System for Cynomolgus Monkeys with Surgery-Induced Acute Renal Failure: A Preclinical Study

Renal dysfunction is one of the most common complications of liver cirrhosis and is associated with increased morbidity and mortality. However, no available technology can simultaneously support liver and renal function in these patients. The aim of this study was to evaluate the safety and efficacy of an artificial liver and renal support system in cynomolgus monkeys with surgery-induced ARF. The ARF model was established by ligature of bilateral renal arteries in eight cynomolgus monkeys, which were randomly divided into a treatment group (n = 4) and control group (n = 4). Biochemical indexes were determined before and after surgery. Blood endotoxin levels, biochemical indexes, and bacterial cultures were assessed at 0, 3, and 6 h during treatment. System pressures and vital signs were recorded at 1 h intervals. Pathological examination was performed after death. ARF was successfully established, based on significant elevation of biochemical indexes and pathological examination. The treatment group had significantly reduced biochemical indexes relative to the control group. Measurement of blood endotoxins and aerobic and anaerobic bacteria cultures indicated no bacterial growth. The system pressures and vital signs were stable during treatment. The results indicate that our support system for the treatment of cynomolgus monkeys with surgery-induced acute renal failure is safe and effective.

Uremic encephalopathy in a rhesus macaque (Macaca mulatta): A case report and a brief review of the veterinary literature

BACKGROUND

Uremic encephalopathy is uncommon yet is one of the most severe complications of renal failure. We present a case of acute renal failure and associated cerebral and vascular lesions consistent with uremic encephalopathy in a rhesus macaque (Macaca mulatta).

METHODS

A 14-year-old, female, specific-pathogen-free rhesus macaque presented in lateral recumbency, obtunded, severely dehydrated, and hypothermic, with severe azotemia, mild hyponatremia, hypokalemia, hypochloremia, increased anion gap, and hypercholesterolemia. Due to poor prognosis, the animal was euthanized and a complete necropsy was conducted.

RESULTS

The animal had diffuse proximal renal tubular epithelial necrosis and loss; regeneration of tubular epithelium was not observed. There was bilateral necrosis and loss of neurons and glial cells in the hippocampus and deep cerebral cortex with edema and multifocal areas of hemorrhage.

CONCLUSION

We present the first reported case of uremic encephalopathy in a rhesus macaque and describe the associated cerebral and vascular lesions.

Kidney disease models: tools to identify mechanisms and potential therapeutic targets

Acute kidney injury (AKI) and chronic kidney disease (CKD) are worldwide public health problems affecting millions of people and have rapidly increased in prevalence in recent years. Due to the multiple causes of renal failure, many animal models have been developed to advance our understanding of human nephropathy. Among these experimental models, rodents have been extensively used to enable mechanistic understanding of kidney disease induction and progression, as well as to identify potential targets for therapy. In this review, we discuss AKI models induced by surgical operation and drugs or toxins, as well as a variety of CKD models (mainly genetically modified mouse models). Results from recent and ongoing clinical trials and conceptual advances derived from animal models are also explored.

Effect of Helichrysum plicatum DC. subsp. plicatum ethanol extract on gentamicin-induced nephrotoxicity in rats

The aim of this study was to evaluate the possible therapeutic or protective effects of Helichrysum plicatum DC. subsp. plicatum ethanol extract (HPE) against gentamicin-induced nephrotoxicity. Thirty-six Sprague Dawley male rats weighing between 200 and 250 g were used as live material. They were formed into six groups containing 6 rats each and were allowed to adapt to laboratory conditions for 7 d. Group I: control, 5% DMSO intraperitoneal (i.p.); Group II: HPE 100 mg/(kg·d) i.p.; Group III: HPE 200 mg/(kg·d) i.p.; Group IV: gentamicin as 80 mg/(kg·d) i.p.; Group V: gentamicin as 80 mg/(kg·d) i.p.+HPE 100 mg/(kg·d) i.p.; and Group VI: gentamicin as 80 mg/(kg·d) i.p.+HPE 200 mg/(kg·d) i.p. for 8 d. Following treatment, serum, liver, and kidney tissues were used to assess blood urea nitrogen (BUN), creatinine, enzymatic and non-enzymatic antioxidants, and lipid peroxidation. Gentamicin significantly increased serum BUN, creatinin, and liver and kidney levels of malondialdehyde (MDA). It also decreased the activity of catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD). Treatment with the HPE 100 mg/kg reversed gentamicin-induced alterations as evidenced by decreased serum BUN and creatinin, liver and kidney oxidant marker, and tubular necrosis as well as by an increase in antioxidant enzymes. It was found that HPE 200 mg/kg significantly increased liver and kidney tissue MDA levels in nephrotoxicity in rats. As a result, these findings support the proposition that HPE in 100 mg/kg dose demonstrates in the kidney and liver as free radicals and scavenger to prevent the toxic effects of gentamicin in both the biochemical and histopathology parameters.

Essential Elements as Biomarkers of Acute Kidney Injury and Spontaneous Reversion

Acute kidney injury (AKI) is an important health problem and can be caused by number of factors. The use of aminoglycosides, such as gentamicin, is one of these factors. Recently, an effort has been made to find biomarkers to guide treatment protocols. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to estimate the contents of Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn in serum and urine of the healthy, AKI, and spontaneous recovery (SR) groups of animals. The animal model of AKI and SR was validated by measuring serum and urinary urea and creatinine. The quantitative determination of the elements showed a decrease in serum levels of Ca, and Fe in the AKI group (P<0.01 vs. healthy), with a return to normal levels in the SR group, without a significant difference between the healthy and SR groups. In the urine samples, there was a decrease in P and Na levels in the AKI group (P<0.001 and P<0.01 vs. healthy), but Ca levels were increased in this group compared with the healthy and SR groups (P<0.01). These findings indicate that mineral elements might be useful as biomarkers for AKI.