Contralateral Nephrectomy Research Articles

Repeated ischemia/reperfusion before contralateral nephrectomy leads to acceleration of AKI to CKD progression in rats

Repeated ischemia/reperfusion before contralateral nephrectomy leads to acceleration of AKI to CKD progression in rats

Синергизм карбамилированного дарбэпоэтина и Л-этоксидола в модели экспериментальной ишемии почки

AIM to determine the efficiency of different doses of erythropoietin and carbamylated darbepoetin, to prove experimentally the possibility of increasing the efficiency of carbamylated darbepoetin when using the levorotatory stereoisomer of ethoxidol. MATERIALS AND METHODS On the model of ischemia-reperfusion injury in male CD-1 mice that were undergone to contralateral nephrectomy, the nephroprotective effect of different doses of erythropoietin alfa, carbamylated darbepoetin, L-ethoxidol (the levorotatory enantiomer of ethylmethylhydroxypyridine malate), and the combined use of L-ethapylated carboxypyridine malate and L-etapoietin alfa was studied. The parameters of microcirculation and glomerular filtration rate were studied one day after 30-minute ischemia. RESULTS It has been established that the prophylactic use of erythropoietin alfa and carbamylated darbepoetin in the model of ischemia-reperfusion injury of a single kidney reduces the severity of microcirculatory impairment and ensures the preservation of the glomerular filtration rate in dose-dependent manner. The synergistic effect of L-ethoxidol and carbamylated darbepoetin was found when these substances were used together. CONCLUSION Prevention of ischemia-reperfusion kidney injury by analogs of human erythropoietin and their combination with ethylmethylhydroxypyridine derivatives is experimentally-proved.

Role of Akt1 in renal fibrosis and tubular dedifferentiation during the progression of acute kidney injury to chronic kidney disease.

Background/AimsAcute kidney injury (AKI) is an underestimated yet important risk factor for the development of chronic kidney disease (CKD), characterized by tubulointerstitial fibrosis and tubular dedifferentiation. Tubular dedifferentiation, which is associated with the loss of epithelial markers and the gain of mesenchymal features, is thought to be involved in tubulointerstitial fibrosis. As protein kinase B/Akt is involved in the development of CKD, we investigated the role of Akt1, one of the three Akt isoforms, in a murine model of AKI-to-CKD progression.MethodsWe subjected C57BL/6 male mice to unilateral ischemia-reperfusion injury (UIRI) and harvested their kidneys after 6 weeks. Mice were divided into four groups, namely, wild-type (WT) UIRI, Akt1−/− UIRI, WT sham, and Akt1−/− sham.ResultsAkt1 (but not Akt2 or Akt3) was markedly activated in WT UIRI mice than in WT sham mice. Tubulointerstitial fibrosis and tubular dedifferentiation significantly increased in WT UIRI mice, but were attenuated in Akt1−/− UIRI mice. Both WT UIRI and Akt1−/− UIRI mice showed markedly upregulated transforming growth factor-β1 (TGF-β1)/Smad signaling compared with WT sham mice. However, TGF-β1/Smad expression did not differ between the two groups. The levels of phosphorylated GSK-3β, β-catenin, and Snail were attenuated in Akt1−/− UIRI mice compared with those in WT UIRI mice.ConclusionsDeletion of Akt1 results in the attenuation of renal fibrosis and tubular dedifferentiation, independent of TGF-β1/Smad signaling, during AKI-to-CKD progression in a UIRI without contralateral nephrectomy model. Thus, Akt1 may serve as a therapeutic target in AKI-to-CKD progression.

Kidney Outcomes and Hypertension in Survivors of Wilms Tumor: A Prospective Cohort Study

To assess the prevalence of therapy-related kidney outcomes in survivors of Wilms tumor (WT). This prospective cohort study included survivors of WT who were ≥5years old and ≥1year from completing therapy, excluding those with preexisting hypertension, prior dialysis, or kidney transplant. Participants completed 24-hour ambulatory blood pressure monitoring (ABPM). Abnormal blood pressure (BP) was defined as ≥90th percentile. Masked hypertension was defined as having normal office BP and abnormal ABPM findings. Urine was analyzed for kidney injury molecule-1, interleukin-18, epidermal growth factor, albumin, and creatinine. The estimated glomerular filtration rate (eGFR) was calculated using the bedside chronic kidney disease in children equation. Recent kidney ultrasound examinations and echocardiograms were reviewed for contralateral kidney size and left ventricular hypertrophy, respectively. Clinical follow-up data were collected for approximately 2years after study enrollment. Thirty-two participants (median age, 13.6years [IQR, 10.5-16.3years]; 75% stage 3 or higher WT) were evaluated at a median of 8.7years (IQR, 6.5-10.8years) after therapy; 29 participants underwent unilateral radical nephrectomy, 2 bilateral partial nephrectomy, and 1 radical and contralateral partial nephrectomy. In this cohort, 72% received kidney radiotherapy and 75% received doxorubicin. Recent median eGFR was 95.6mL/min/1.73m2 (IQR, 84.6-114.0; 11 [34%] had an eGFR of <90mL/min/1.73m2). Abnormal ABPM results were found in 22 of 29 participants (76%), masked hypertension in 10 of 29 (34%), and microalbuminuria in 2 of 32 (6%). Of the 32 participants, 22 (69%) had abnormal epidermal growth factor; few had abnormal kidney injury molecule-1 or interleukin-18. Seven participants with previous unilateral nephrectomy lacked compensatory contralateral kidney hypertrophy. None had left ventricular hypertrophy. In survivors of WT, adverse kidney outcomes were common and should be closely monitored.

Akt1 is involved in tubular apoptosis and inflammatory response during renal ischemia-reperfusion injury.

Renal ischemia-reperfusion injury (IRI) is one of the major causes of acute kidney injury (AKI). Although Akt is involved in renal IRI, it is unclear as to which Akt isoform plays an important role in renal IRI. In this study, we investigated the role of Akt1 in renal IRI. We subjected the C57BL/6 male mice to unilateral IRI with contralateral nephrectomy. Two days after IRI, IRI-kidneys were harvested. The mice were divided into four groups: wild type (WT) IRI, Akt1-/- IRI, WT sham, and Akt1-/- sham. We found that Akt1, not Akt2 or Akt3, was markedly activated in WT IRI than in WT sham mice. The histologic damage score and serum creatinine level significantly increased in WT IRI mice, the increase being the highest in Akt1-/- IRI mice. The number of TdT-mediated dUTP nick-end labeling (TUNEL)-positive tubular cells and expression of cleaved caspase-3/Bax were higher in Akt1-/- IRI mice than in WT IRI mice. The expression of Bcl-2 was lower in Akt1-/- IRI mice than in WT IRI mice. The expression of tumor necrosis factor-α/interleukin-6/interleukin-1β and number of F4/80-positive macrophages were markedly higher in Akt1-/- IRI than in WT IRI mice. The expression of phosphorylated nuclear factor-κB p65 was also higher in Akt1-/- IRI mice than in WT IRI mice. Our results show that Akt1 deletion exacerbates kidney damage as it increases tubular apoptosis and inflammatory response during renal IRI. Akt1 could be a potential therapeutic target for developing treatments against IRI-induced AKI.

How Does the Remaining Single Kidney Cope After Contralateral Nephrectomy of the Kidney Donor? A Single-Center Cohort Study.

IntroductionImmediately after kidney donation, the remaining kidney will undergo hyperfiltration and work at a higher level to compensate for the other kidney's loss. It is estimated that 70% of the baseline renal function before the donation is recovered post-donation. However, factors that determine the post-donation renal compensation are not well understood.MethodsWe conducted a retrospective study of 190 consecutive kidney donors who completed a one-year follow-up in order to predict the factors affecting the function of the remaining kidney post-contralateral nephrectomy.ResultsWe enrolled 190 living kidney donors who had completed at least one year of follow-up after nephrectomy. Among the participants, 149 (78.4%) were males and 41 (21.6%) were females. The mean age of the participants was 31.33 ±7.9 years and the mean body mass index (BMI) was 25.6 ±3.9 kg/m2. Before kidney donation, the mean estimated glomerular filtration rate (eGFR) and serum creatinine were 114.31 ±15.94 ml/min/1.73 m2 and 71.60 ±10.62 mmol/min, respectively. At the one-year follow-up, the mean eGFR was 77.97 ±14.44 ml/min/1.73 m2 and serum creatinine was 100.84 ±20.15 mmol/min. The female gender [odds ratio (OR): 20.6, 95% CI: 3.9-107.7, p: <0.001] and having a higher baseline eGFR (OR: 8.8, 95% CI: 1.6-45.8, p = 0.01) were found to be significant predictors of having a better eGFR at one year post-nephrectomy.ConclusionsFemale gender and pre-donation low serum creatinine and high eGFR were the significant predictors of better kidney function at one year post-contralateral nephrectomy. However, further studies with longer follow-up durations are needed to better assess the factors that could predict renal compensation and the renal compensation rate's suitability as a prognostic measure for long-term renal outcomes.

A Preclinical Systematic Review of Curcumin for Protecting the Kidney with Ischemia Reperfusion Injury.

Renal ischemia-reperfusion injury (RIRI) refers to a phenomenon associated with dysfunction of the kidney and tissue damage. Unfortunately, no specific drugs have been found that effectively prevent and treat RIRI. Curcumin (Cur), a polyphenol extracted from turmeric, possesses a variety of biological activities involving antioxidation, inhibition of apoptosis, inhibition of inflammation, and reduction of lipid peroxidation. Eight frequently used databases were searched using prespecified search strategies. The CAMARADES 10-item quality checklist was used to evaluate the risk of bias of included studies, and the RevMan 5.3 software was used to analyze the data. The risk of bias score of included studies ranged from 3 to 6 with an average score of 5.22. Compared with the control group, Cur significantly alleviated renal pathology, reduced blood urea nitrogen and serum creatinine levels, and improved inflammatory indexes, oxidant, and apoptosis in RIRI animal models. Despite the heterogeneity of the response to Cur in terms of serum creatinine, BUN, TNF-alpha, and SOD, its effectiveness for improving the injury of RIRI was remarkable. In the mouse model subgroup of serum creatinine, the effect size of the method of unilateral renal artery ligation with contralateral nephrectomy and shorter ischemic time showed a greater effect than that of the control group. No difference was seen in the methods of model establishment, mode administration, or medication times. The preclinical systematic review provided preliminary evidence that Cur partially improved RIRI in animal models, probably via anti-inflammatory, antioxidant, antiapoptosis, and antifibrosis activities and via improving microperfusion. ARRIVE guidelines are recommended; blinding and sample size calculation should be focused on in future studies. These data suggest that Cur is a potential renoprotective candidate for further clinical trials of RIRI.

Ex Vivo Administration of Mesenchymal Stromal Cells in Kidney Grafts Against Ischemia-reperfusion Injury-Effective Delivery Without Kidney Function Improvement Posttransplant.

Mesenchymal stromal cell (MSC) therapy may improve renal function after ischemia-reperfusion injury in transplantation. Ex vivo renal intraarterial administration is a targeted delivery method, avoiding the lung vasculature, a known barrier for cellular therapies. In a randomized and blinded study, we tested the feasibility and effectiveness of MSC therapy in a donation after circulatory death autotransplantation model to improve posttransplant kidney function, using an ex vivo MSC delivery method similar to the clinical standard procedure of pretransplant cold graft flush. Kidneys exposed to 75 minutes of warm ischemia and 16 hours of static cold storage were intraarterially infused ex vivo with 10 million male porcine MSCs (Tx-MSC, n = 8) or vehicle (Tx-control, n = 8). Afterwards, the kidneys were autotransplanted after contralateral nephrectomy. Biopsies an hour after reperfusion confirmed the presence of MSCs in the renal cortex. Animals were observed for 14 days. Postoperatively, peak plasma creatinine was 1230 and 1274 µmol/L (Tx-controls versus Tx-MSC, P = 0.69). During follow-up, no significant differences over time were detected between groups regarding plasma creatinine, plasma neutrophil gelatinase-associated lipocalin, or urine neutrophil gelatinase-associated lipocalin/creatinine ratio. At day 14, measured glomerular filtration rates were 40 and 44 mL/min, P = 0.66. Renal collagen content and fibrosis-related mRNA expression were increased in both groups but without significant differences between the groups. We demonstrated intraarterial MSC infusion to transplant kidneys as a safe and effective method to deliver MSCs to the graft. However, we could not detect any positive effects of this cell treatment within 14 days of observation.

Measuring volumetric segmentation changes in the ipsilateral and contralateral kidney postpartial nephrectomy

ObjectiveTo analyze the volumetric changes of the ipsilateral and contralateral kidneys and their effect on functional outcome post partial nephrectomy using segmentation analysis. Patients and methodsWe have analyzed the data of 119 patients from a single surgeon series of partial nephrectomy patients. Median follow-up was 11.40 months. Patients with bilateral tumors, and solitary kidney were excluded from analysis. Volumetric measurements were performed using a semiautomated tissue segmentation tool. A simple linear regression model to assess the predictors for parenchymal volume loss (PVL). A multivariable linear regression model was used to evaluate the association between PVL and warm ischemia time (WIT), controlling for other factors. ResultsMean WIT was 12.09 ± 4.40 minutes and the mean percentage decrease in the volume of the operated kidney was 16.99 ± 13.49%. WIT (β = 1.24, P < 0.001) and tumor complexity (simple vs. intermediate, β = 0.06, P = 0.984; simple vs. high, β = 11.62,P = 0.007) were associated with PVL. A 1 minute increase in WIT was associated with an increase in the percentage volume loss in the operated kidney by 1.38% (β = 1.20, P < 0.001). Patients with high tumor complexity (β = 11.17, P = 0.009) had a significantly higher percentage volume loss compared to patients with simple tumor complexity. Ipsilateral PVL (β = −0.35, P = 0.015) and male gender (β = −9.89, P = 0.021) were associated with change in eGFR. After adjusting for confounders, % volume loss (β = −0.32, P < 0.001) remained a significant predictor for contralateral hypertrophy. ConclusionTumor complexity results in higher WIT and increased PVL as measured by volumetric segmentation. PVL is a key factor associated with functional outcome, and is directly linked to WIT. Increased PVL is also associated with decreased contralateral hypertrophy. Prospective studies with larger samples sizes will be required to validate our findings.

P0546EARLY, BUT NOT LATE, CONTRALATERAL NEPHRECTOMY OVERCOMES PROGRESSION TO CKD AFTER UNILATERAL ISCHEMIC INJURY

Abstract Background and Aims It is increasingly clear that acute kidney injury (AKI) can result in the development of chronic kidney disease (CKD) in humans. Murine renal unilateral ischemia-reperfusion injury (UIRI) models this AKI-to-CKD progression in the injured kidney in the presence of its healthy counterpart (Le Clef et al, Plos One 2016). In mice, we and others demonstrated that contralateral nephrectomy (Nx), when performed shortly after UIRI (i.e. 3 days), is able to significantly attenuate the progression to CKD. Although non-translatable, Nx can be considered an experimental therapeutic intervention that incites inherent physiological recovery mechanisms in the kidney. Here, we investigate in rats to what extent contralateral Nx is able to attenuate or revert CKD progression when performed well beyond the acute injury phase, i.e. with increased Nx delay time after UIRI. Method AKI was induced in male Wister rats by left UIRI for 60 min at 35°C core body temperature after which contralateral Nx was performed 3, 10 or 20 days later, or no Nx was performed. Control animals underwent sham-UIRI and sham-Nx 3 days later. Renal function was assessed by serum creatinine and transcutaneous GFR measurement 24h and 72h after Nx and weekly thereafter. Rats were euthanized 11 weeks after Nx. Kidneys were weighed and histology was evaluated by PAS stain for overall morphology and Sirius Red stain for interstitial fibrosis. Results When no Nx was performed, renal function of the injured kidney decreased 44% compared to control animals at week 11. Nx at day 3 induced full functional recovery from week 5 after Nx on, whereas Nx at day 10 and 20 both lead to a persistent 20% loss of renal function at week 9 after Nx (p&amp;lt;0.05). Nx at day 3 was able to attenuate renal atrophy and fibrotic tubulointerstitial expansion. Nx at day 10 and 20 were less efficient and led to 1.6 (p&amp;gt;0.05) and 2.6 (p&amp;lt;0.05) fold increase of tubulointerstitial area compared to controls. Nx at day 3 and 10 induced a significant increase in renal mass-to-body weight ratio compared to control from 2.9±0.1 mg/g (control) to 4.6±0.4 mg/g (day 3) and 4.8±0.3 mg/g (day 10) respectively. When Nx was performed at day 20 or no Nx was performed, renal mass-to-body weight ratio did not differ significantly from control animals, however, parallel with renal function, histopathology was considerably worse. Conclusion Early contralateral Nx after UIRI rescues renal function and morphology, whereas delayed Nx does not allow full recovery of the injured kidney. There was no additional functional loss when Nx was performed on day 20 versus day 10, though, histopathology aggravated. These results imply that a damaged kidney loses its intrinsic (compensatory) recovery potential over time and that an early intervention is crucial for averting CKD outcome after AKI.

P0529THE DIFFERENCE IN DIETARY RESTRICTION-INDUCED NEPHROPROTECTIVE MECHANISMS IN YOUNG AND OLD ANIMALS

Abstract Background and Aims Acute kidney injury (AKI) is a widespread disease affecting mostly old people. Dietary restriction (DR), based on the reduction of food intake, is believed to be one of the most efficient approaches ameliorating damage in different pathological conditions including age-associated diseases. The aim of the study was to investigate the protective mechanisms of DR in the model of AKI in young and old rats. Method All experiments were made on young (3-4 months) and old (22-24 months) male rats. DR was performed by limiting the amount of food for 35% of the ad libitum (AL) daily intake. Since earlier, we showed ineffectiveness of 4-weeks DR in old rats, in this study we applied 35% DR lasting 8 weeks for old rats and 4 weeks for young rats. During DR, we registered the weight loss and measured the level of adiponectin, as this hormone is closely associated with adipose tissue metabolism. Renal ischemia/reperfusion (I/R) was used as a model of ischemic AKI. I/R was performed by clamping the left renal pedicle for 40 minutes followed by reperfusion with simultaneous contralateral nephrectomy. The severity of AKI was evaluated by measuring blood urea nitrogen (BUN), serum creatinine (SCr) and the levels of protein biomarkers of AKI (NGAL and L-FABP) in urine. Proliferation in kidney epithelium in response to I/R was analyzed by PCNA protein level in kidney tissue. We evaluated the function of mitochondria by measuring TMRE/MitoTracker Green ratio in vital kidney slices; in kidney homogenates, we also analyzed levels of Bcl-XL and Bcl-XS proteins. The production of reactive oxygen species (ROS) was evaluated by staining vital kidney slices with DCF. The content of lipid peroxidation products was measured using Image-iT Lipid Peroxidation Kit, and the level of carbonylated proteins was determined by OxyBlot Protein Oxidation Detection Kit. The activation of autophagic-lysosomal system was estimated by western blotting to LC3 II/LC3 I ratio and LAMP1 level, as well as by staining vital kidney slices with LysoTracker Green probe. Results The body weight of rats during DR dropped as far as 20% by the end of 4 weeks in young rats and 30% by the end of 8 weeks in old rats. Nevertheless, adiponectin concentration elevated during DR only in the serum of young rats. DR strongly influenced mitochondria function, in particular, elevated mitochondrial membrane potential both in kidney cells of young and old rats. DR also resulted in increasing the Bcl-XL level. We revealed the decrease of ROS and lipid peroxidation products in vital kidney slices, but only in kidneys of young rats. However, DR reduced the content of carbonyl groups more than 2 times in animals of both ages. We showed that activation of autophagy in response to DR and I/R occurred only in the kidneys of young rats, indicating deterioration of autophagy signaling in old animals. We also found that 48 h after I/R PCNA level increased 19 times in young kidney, although old rats showed only 4-fold elevation of kidney cells proliferation. Estimation of kidney injury markers (NGAL, L-FABP) in urine revealed that 2-month DR led to some protection in old rats. Nonetheless, despite all positive alterations in kidney tissue of old rats, DR was not able to ameliorate impairment of kidney function after I/R, whereas all young rats showed significant improvement of SCr and BUN levels. Conclusion Short-term DR has a significant nephroprotective effect against renal I/R in young rats. Old animals require longer periods of food restriction, after which some protective alterations are observed. We propose, protection of kidney in old and young rats is implemented through slightly different mechanisms and some of them are missing in old animals.

Post-Ischemic Renal Fibrosis Progression Is Halted by Delayed Contralateral Nephrectomy: The Involvement of Macrophage Activation

(1) Background: Successful treatment of acute kidney injury (AKI)-induced chronic kidney disease (CKD) is unresolved. We aimed to characterize the time-course of changes after contralateral nephrectomy (Nx) in a model of unilateral ischemic AKI-induced CKD with good translational utility. (2) Methods: Severe (30 min) left renal ischemia-reperfusion injury (IRI) or sham operation (S) was performed in male Naval Medical Research Institute (NMRI) mice followed by Nx or S one week later. Expression of proinflammatory, oxidative stress, injury and fibrotic markers was evaluated by RT-qPCR. (3) Results: Upon Nx, the injured kidney hardly functioned for three days, but it gradually regained function until day 14 to 21, as demonstrated by the plasma urea. Functional recovery led to a drastic reduction in inflammatory infiltration by macrophages and by decreases in macrophage chemoattractant protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-α) mRNA and most injury markers. However, without Nx, a marked upregulation of proinflammatory (TNF-α, IL-6, MCP-1 and complement-3 (C3)); oxidative stress (nuclear factor erythroid 2-related factor 2, NRF2) and fibrosis (collagen-1a1 (Col1a1) and fibronectin-1 (FN1)) genes perpetuated, and the injured kidney became completely fibrotic. Contralateral Nx delayed the development of renal failure up to 20 weeks. (4) Conclusion: Our results suggest that macrophage activation is involved in postischemic renal fibrosis, and it is drastically suppressed by contralateral nephrectomy ameliorating progression.

Meprin β expression associated with decreased proximal tubule PKA Cβ levels in ischemia/reperfusion‐induced acute kidney injury

Ischemia/ reperfusion (IR) is a leading cause of acute kidney injury (AKI). Meprins are metalloproteases that are expressed abundantly in the brush border membranes of renal proximal tubules (PTs). The levels of expression and the localization of meprins were previously shown to associate with IR‐induced AKI. Studies from our group showed that meprin B proteolytically cleaves three isoforms of the catalytic subunit of PKA, namely, PKA Cα1, Cβ1, and Cβ2. The cleavage by meprin B resulted in decreased kinase activity of these PKA C isoforms. Furthermore, the total levels of PKA C were significantly decreased in the meprin expressing PTs at 3h post‐IR when compared to distal tubules which are deficient in meprins. The objective of the current study was to determine which of the PKA C isoforms is impacted by meprin B and thus involved in the IR‐response mediated by meprin β. To this end, surgical procedures were used to induce unilateral IR (with contralateral nephrectomy) in 12‐week old wild‐type (WT) and meprin β knockout (βKO) mice on a C57BL/6 background. Kidney tissues were harvested at 6h post IR. Kidney proteins were extracted and fractionated into BBM‐, cytosolic‐, and nuclear‐enriched fractions. Western blot analysis was used to determine the levels of Cα and Cβ in the cytosolic‐ and nuclear‐enriched fractions. Immunofluorescence staining was used to determine the localization of PKA C (total), Cβ, and Cα. Statistical analysis utilized 2‐way ANOVA. The total levels of PKA C decreased in kidneys from WT mice subjected to IR but not in βKO counterparts. However, use of isoform‐specific antibodies demonstrated increases in the levels of Cβ but not Cα in the cytosolic‐ and nuclear‐enriched fractions. Two Cβ protein bands (41 and 37 kDa) were detected in cytosolic‐ and one band (41 kDa) in nuclear‐enriched fractions. The levels of the 41 kDa Cβ protein species were higher in lysates from WT kidneys at 6h post‐IR (P=0.0001). In contrast, the 37 kDa species, which was detected in nuclear‐enriched fractions only, decreased in βKO (P=0.002) but not in WT kidneys subjected to IR. A closer histological analysis of kidney sections showed that the level of damage to the brush borders was not uniform in all proximal tubules. More importantly, immunohistochemical analysis showed that the PKA Cβ levels decreased in damaged/injured meprin β expressing PTs but appeared to increase in intact PTs. These changes were not observed in PTs from meprin βKO kidneys. Individual interstitial cells (presumed to be resident macrophages) also stained positively for Cβ in WT but not in βKO kidney sections. Taken together, the data suggest that the PKA Cβ isoform is involved in the response to IR‐induced renal injury. The Cβ levels are known to be abundant in lymphoid tissue but our data indicate expression in immune cells resident in kidney tissue as well as epithelial tubular cells in response to IR‐induced AKI. More studies are needed to determine the response genes mediated by PKA Cβ signaling in IR to increase our understanding of how meprins modulate kidney injury in mice.Support or Funding InformationThis study was supported by the National Institute of Health/National Institutes of General Medical Sciences (NIGMS) Grant #s SC3GM102049 and SC1GM118271

Renal Protection against Post Ischemia‐reperfusion Injury in Fatty Acid Amide Hydrolase Knockout Mice

Renal fibrosis is a typical characteristic of progressive chronic kidney disease (CKD). Current treatment options to slow renal fibrosis are still very limited. Endocannabinoids known as anandamide and 2‐arachidonoylglycerol play a critical role in regulating renal physiology via cannabinoid receptors (CB1 and CB2). Fatty acid amide hydrolase (FAAH) is one of the major enzymes to metabolize endocannabinoids. Studies have shown that endocannabinoid system is present in the kidney and that CB1 and CB2 are involved in CKD. However, the role of FAAH in CKD remains unclear. The present study tested the hypothesis that FAAH pathway participates in the kidney damage in post ischemia‐reperfusion (PIR) model, which produces chronic renal injury and fibrosis, using FAAH knockout mice. Male wild type C57BL6 (WT) and Faah−/− mice were subjected to PIR by unilateral ischemia‐reperfusion and contralateral nephrectomy 10 days after ischemia‐reperfusion. Compared with WT mice, Faah−/− mice showed significantly reduced BUN (mean: 22.0 ± 1.16, 102.0± 9.50, and 61± 4.35 mg/dL in WT‐shame, WT‐PIR, and Faah−/−‐PIR mice, respectively, p&lt;0.05) and plasma creatinine level (mean: 0.18 ± 0.02, 1.18 ± 0.06, and, 0.54± 0.05 mg/dL in WT‐shame, WT‐PIR, and Faah−/−‐PIR mice, respectively, p&lt;0.05) in response to PIR. Western blot analysis showed that increased expression of fibrotic protein alpha‐smooth muscle actin in the kidneys were significantly reduced in Faah−/− mice, whereas remained high in WT mice under PIR (1.85‐fold versus 2.46‐fold, p&lt;0.05). Collagen staining by Sirius Red showed the same pattern as alpha‐smooth muscle actin expression in the kidneys from different groups of mice. Histological evaluation by Periodic acid–Schiff (PAS) staining showed that Faah−/− mice exhibited less tissue damage especially in tubular structure in response to PIR compared with WT mice. These results suggest that inhibition of FAAH may preserve renal function and prevent renal fibrosis and that FAAH may serve as a target for developing novel and effective treatment for CKD.Support or Funding InformationNIH grants R01DK54927, R01DK107991, R01HL145163

Pathophysiology of unilateral ischemia-reperfusion injury: importance of renal counterbalance and implications for the AKI-CKD transition.

Unilateral ischemia-reperfusion (UIR) injury leads to progressive renal atrophy and tubulointerstitial fibrosis (TIF) and is commonly used to investigate the pathogenesis of the acute kidney injury-chronic kidney disease transition. Although it is well known that contralateral nephrectomy (CNX), even 2 wk post-UIR injury, can improve recovery, the physiological mechanisms and tubular signaling pathways mediating such improved recovery remain poorly defined. Here, we examined the renal hemodynamic and tubular signaling pathways associated with UIR injury and its reversal by CNX. Male Sprague-Dawley rats underwent left UIR or sham UIR and 2 wk later CNX or sham CNX. Blood pressure, left renal blood flow (RBF), and total glomerular filtration rate were assessed in conscious rats for 3 days before and over 2 wk after CNX or sham CNX. In the presence of a contralateral uninjured kidney, left RBF was lower (P < 0.05) from 2 to 4 wk following UIR (3.6 ± 0.3 mL/min) versus sham UIR (9.6 ± 0.3 mL/min). Without CNX, extensive renal atrophy, TIF, and tubule dedifferentiation, but minimal pimonidazole and hypoxia-inducible factor-1α positivity in tubules, were present at 4 wk post-UIR injury. Conversely, CNX led (P < 0.05) to sustained increases in left RBF (6.2 ± 0.6 mL/min) that preceded the increases in glomerular filtration rate. The CNX-induced improvement in renal function was associated with renal hypertrophy, more redifferentiated tubules, less TIF, and robust pimonidazole and hypoxia-inducible factor-1α staining in UIR injured kidneys. Thus, contrary to expectations, indexes of hypoxia are not observed with the extensive TIF at 4 wk post-UIR injury in the absence of CNX but are rather associated with the improved recovery of renal function and structure following CNX.

A Pilot Study of Postoperative Animal Welfare as a Guidance Tool in the Development of a Kidney Autotransplantation Model With Extended Warm Ischemia.

Background.This pilot study aimed to maintain acceptable animal welfare in the development of a porcine autotransplantation model with severe and incremental renal ischemic injury, a model for usage in future intervention studies. Secondary aims were to develop and test methods to collect blood and urine without the need to restrain or use sedative and avoid transportation to optimize welfare of the pig.Methods.Kidneys from 7 female pigs were subjected to incremental durations of warm ischemia (WI) 30, 45, or 75 minutes by left renal artery and vein clamping. After static cold storage, contralateral nephrectomy was performed, and the injured graft was autotransplanted and animals observed for 14 days. Animal welfare was assessed and recorded using a structured scoring sheet before and 4 days after the kidney autotransplantation. Furthermore, blood samples were drawn daily the first week and every second day the following week using a semi-central venous catheter. An ostomy bag around the genitals was tested for urine collection. Measured glomerular filtration rate was calculated using renal clearance of chromium-51-labeled ethylenediamine tetraacetic acid on day 14.Results.None of the 7 animals died during the follow-up. The animal welfare was moderately affected when applying 75 minutes of WI (n = 2), and for that reason WI was not further increased. Pigs with lower WI had no observed welfare issues. With 75 minutes of WI peak, plasma creatinine was 1486 and 1317 µmol/L, reached on day 4. Lowest glomerular filtration rate levels were observed in the pigs with 75 minutes of WI.Conclusions.WI up to 75 minutes caused the intended severely impaired renal function without significantly compromising animal welfare. Blood and urine was collected postoperatively without sedation of the pigs or use of a metabolic cage.

Establishment of Renal Failure Models by Laparoscopy in Bama Pigs Which Underwent Partial Nephrectomy and Radical Contralateral Nephrectomy.

IntroductionThe miniature pig possesses unmatched advantages as an animal model because of its high homology with humans. Our experiment aimed to build a chronic renal failure (CRF) model in pigs via laparoscopy.Material and MethodsLaparoscopic surgery was performed twice to build a CRF model. The first surgery was a left partial nephrectomy and the second was a right radical nephrectomy. Pigs were grouped by the total renal tissue to be resected: ⅔, ¾ or ⅚. Physiological parameters (rectal temperature and heart rate), haematological parameters (WBC and RBC) and renal function (serum creatinine – CR and blood urea nitrogen – BUN) were measured preoperatively and every week postoperatively.ResultsAfter renal resection the pigs manifested chronic renal failure. Heart rate and body temperature declined to varying degrees over 12 postoperative weeks. No significant difference was observed between the different groups. The result of renal function tests found that postoperative serum CR and BUN in all groups were continuously elevated, and the level of serum CR at two weeks post procedure differed very significantly from its preoperative value (P < 0.05). BUN was significantly elevated at one week (P < 0.05). The renal function decreased significantly faster in the ⅚ group than in the other two groups. The trend of renal function change was similar among groups, but progress was slower in the ⅔ and ¾ groups.Conclusion⅚ kidney resection was the optimal miniature pig model of CRF.

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.

Prospective evaluation of CT-guided HDR brachytherapy as a local ablative treatment for renal masses: a single-arm pilot trial

In this pilot trial, we investigate the safety of CT-guided high-dose-rate brachytherapy (HDR-BT) as alocal ablative treatment for renal masses not eligible for resection or nephrectomy. We investigated renal function after irradiation by HDR-BT in 16patients (11male, 5female, mean age 76years) with 20renal lesions (renal cell carcinoma n = 18; renal metastases n = 2). Two patients had previous contralateral nephrectomy and two had ipsilateral partial nephrectomy. Six lesions had ahilar localization with proximity to the renal pelvis and would have not been favorable for thermal ablation. Renal function loss was determined within 1year after HDR-BT by renal scintigraphy and laboratory parameters. Further investigations included CT and MRI every 3months to observe procedural safety and local tumor control. Renal function tests were analyzed by Wilcoxon's signed rank test with Bonferroni-Holm correction of p-values. Survival and local tumor control underwent aKaplan-Meier estimation. Median follow-up was 22.5months. One patient required permanent hemodialysis 32months after repeated HDR-BT and contralateral radiofrequency ablation of multifocal renal cell carcinoma. No other patient developed asignificant worsening in global renal function and no gastrointestinal or urogenital side effects were observed. Only one patient died of renal tumor progression. Local control rate was 95% including repeated HDR-BT of two recurrences. HDR-BT is afeasible and safe technique for the local ablation of renal masses. AphaseII study is recruiting to evaluate the efficacy of this novel local ablative treatment in alarger study population.

Experience in diagnosis and treatment of non-hereditary bilateral synchronous renal carcinoma

Objective To investigate the principles of diagnosis and treatment of non-hereditary bilateral synchronous renal cell carcinoma. Methods This retrospective study analyzed 36 cases of non-hereditary bilateral synchronous renal cell carcinoma in our hospital from January 2008 to December 2016, including 30 males and 6 females. A total of 74 renal tumors were found, in which 34 patients had bilateral single kidney tumor and 2 patients had two tumors in one kidney. The diameter of tumors ranged from 1cm to 11 cm, with an average of (6.8±4.1)cm. The patients that underwent nephron-sparing surgery(NSS) got 4-12 points, with an average of (6.1±3.4) points in R. E.N.A.L. score and 3-13 points, with an average of (6.9±3.7) points in Zhongshan score. The patients are classified into 4 groups according to operation methods. In group A, 16 patients underwent bilateral NSS, which the preoperative creatinine was 63-103 μmol/L with an average of (80.9±11.4)μmol/L. In group B, 7 patients underwent one side of NSS before contralateral radical nephrectomy (RN), which preoperative creatinine was 59-87 μmol/L with an average of (75.7±8.9)μmol/L. In group C, 7 patients underwent one side of RN before contralateral NSS, preoperative creatinine was 57-107 μmol/L, with an average of (77.6±19.2)μmol/L. In group D, 6 patients underwent one side of NSS or RN and spare the contralateral side, 2 of which shifted from NSS to RN after finding tumor invaded pelvis and upper ureter during surgery. Of all the 16 patients with bilateral NSS, 4 patients underwent surgery on the side where tumor had a higher score in the first phase and then the side where tumor had a lower score in the second phase, 11 underwent surgeries in an opposite order. One patient underwent bilateral NSS simultaneously. Group A, B and C are taken into final analysis. Result All the 30 patients underwent surgery successfully. The operation time of NSS ranged from 60 to 110 min with an average of (88.6±23.6)min and RN ranged from 40 to 90 min with an average of (72.3±21.4)min. The warm ischemia time of NSS was 12-40 mins with an average of (29.5±9.7)min. The creatinine of Group A was 62-117 μmol/L with an average of (89.4±15.8)μmol/L and 57-392 μmol/L with an average of (129.6±74.9)μmol/L one month after the first and second surgery respectively. The creatinine of Group B was 64-115 μmol/L with an average of (94±14.4)μmol/L and 93-453 μmol/L with an average of (190.4±117.2)μmol/L one month after the first and second surgery respectively. The creatinine of Group C was 84-113 μmol/L with an average of (90.1±12.1)μmol /L and 88-156 μmol/L with an average of (121.4±24.8)μmol/L one month after the first and second surgery respectively. One patient in Group B and C developed lung metastases. One patient in Group B occurred oliguria after the second stage of surgery, and gradually improved after one week of hemodialysis. The creatine showed no significant difference among Group A, B and C before operation, after the first and second stage(P>0.05). Postoperative hospital stay after the first stage surgery was 3-16 days with an average of (6.7±3.4)d, and 3-16 d with an average of (6.2±3.2)d after the second stage, respectively. Conclusions In principle, bilateral renal tumors should be treated with NSS, which can protect renal functions as much as possible. Among patients who can undergo bilateral NSS, the first-stage surgery should be operated on the simpler and easier side to preserve the kidney of one side as much as possible to lay a good foundation for the second stage surgery. Among patients who undergo one side of RN and the other side of NSS, NSS is recommended for the first stage, and RN for the contralateral second stage after the renal function of the operated side was restored. Key words: Renal carcinoma; Surgery; Nephron-sparing surgery