Gender Differences in the Acute Kidney Injury to Chronic Kidney Disease Transition

Sex bias in prediction and diagnosis of cardiac surgery associated acute kidney injury

BACKGROUND

Female sex has been recognized as a risk factor for cardiac surgery associated acute kidney injury (CS-AKI). The current study sought to evaluate whether female sex is a risk factor for CS-AKI, or modifies the association of peri-operative change in serum creatinine with CS-AKI.

METHODS

Observational study of adult patients undergoing cardiac surgery between 2000 and 2019 in a single U.S. center. The main variable of interest was registered patient sex, identified from electronic medical records. The main outcome was CS-AKI within 2 weeks of surgery.

RESULTS

Of 58526 patients, 19353 (33%) were female; 12934 (22%) incurred AKI based on ≥ 0.3 mg/dL or ≥ 50% rise in serum creatinine (any AKI), 3320 (5.7%) had moderate to severe AKI, and 1018 (1.7%) required dialysis within 2 weeks of surgery. Female sex was associated with higher risk for AKI in models that were based on preoperative serum creatinine (OR, 1.35; 95% CI, 1.29-1.42), and lower risk with the use of estimated glomerular filtration, (OR, 0.90; 95% CI, 0.86-0.95). The risk for moderate to severe CS-AKI for a given immediate peri-operative change in serum creatinine was higher in female compared to male patients (p < .0001 and p < .0001 for non-linearity), and the association was modified by pre-operative kidney function (p < .0001 for interaction).

CONCLUSIONS

The association of patient sex with CS-AKI and its direction was dependent on the operational definition of pre-operative kidney function, and differential outcome misclassification due to AKI defined by absolute change in serum creatinine.

Renal vascular control during normothermia and passive heat stress does not differ between healthy younger men and women

Men are likely at greater risk for heat-induced acute kidney injury compared with women, possibly due to differences in vascular control. We tested the hypothesis that the renal vasoconstrictor and vasodilator responses will be greater in younger women compared with men during passive heat stress. Twenty-five healthy adults [12 women (early follicular phase) and 13 men] completed two experimental visits, heat stress or normothermic time-control, assigned in a block-randomized crossover design. During heat stress, participants wore a water-perfused suit perfused with 50°C water. Core temperature was increased by ∼0.8°C in the first hour before commencing a 2-min cold pressor test (CPT). Core temperature remained clamped and at 1-h post-CPT, subjects ingested a whey protein shake (1.2 g of protein/kg body wt), and measurements were taken pre-, 75 min, and 150 min post-protein. Beat-to-beat blood pressure (Penaz method) was measured and segmental artery vascular resistance (VR, Doppler ultrasound) was calculated as segmental artery blood velocity ÷ mean arterial pressure. CPT-induced increases in segmental artery VR did not differ between trials (trial effect: P = 0.142) nor between men (heat stress: 1.5 ± 1.0 mmHg/cm/s, normothermia: 1.4 ± 1.0 mmHg/cm/s) and women (heat stress: 1.4 ± 1.2 mmHg/cm/s, normothermia: 2.1 ± 1.1 mmHg/cm/s) (group effect: P = 0.429). Reductions in segmental artery VR following oral protein loading did not differ between trials (trial effect: P = 0.080) nor between men (heat stress: -0.6 ± 0.8 mmHg/cm/s, normothermia: -0.6 ± 0.6 mmHg/cm/s) and women (heat stress: -0.5 ± 0.5 mmHg/cm/s, normothermia: -1.1 ± 0.6 mmHg/cm/s) (group effect: P = 0.204). Renal vasoconstrictor responses to the cold pressor test and vasodilator responses following an oral protein load during heat stress or normothermia do not differ between younger men and younger women in the early follicular phase of the menstrual cycle.NEW & NOTEWORTHY The mechanisms underlying greater heat-induced acute kidney injury risk in men versus women remain unknown. This study examined renal vascular control, including both vasodilatory (oral protein load) and vasoconstrictor (cold presser test) responses, during normothermia and heat stress and compared these responses between men and women. The results indicated that in both conditions neither renal vasodilatory nor vasoconstrictor responses differ between younger men and younger women.

A short treatment with resveratrol after a renal ischaemia-reperfusion injury prevents maladaptive repair and long-term chronic kidney disease in rats

Acute kidney injury (AKI) often triggers physiological processes aimed at restoring renal function and architecture. However, this response can become maladaptive, leading to nephron loss and fibrosis. Although the therapeutic effects of resveratrol (RSV) are well established, its impact after AKI and for subsequent chronic kidney disease (CKD) remains unclear. This study assessed whether transient administration of RSV following ischaemia-reperfusion injury (IRI) could prevent the progression to CKD. Forty-one male Wistar rats were assigned randomly to sham surgery, bilateral renal ischaemia for 30 min (IR) or IR+RSV. The RSV treatment commenced 24 h after IRI and continued for 10 days. The rats were studied for either 10 days or 5 months, after which kidney function and structure were evaluated. Mitochondrial homeostasis, oxidant defence and renal inflammation state were also evaluated. Despite having the same severity of AKI, rats receiving RSV for 10 days after IRI exhibited significant improvement in kidney histological injury and reduced inflammation, although renal haemodynamic recovery was less pronounced. Resveratrol effectively prevented the elevation of tubular injury-related molecules and profibrotic signalling with reduced myofibroblast proliferation. Furthermore, RSV substantially improved the antioxidant response and mitochondrial homeostasis. After 5 months, RSV prevented the transition to CKD, as evidenced by the prevention of progressive proteinuria, renal dysfunction and tubulointerstitial fibrosis. This study demonstrates that a brief treatment with RSV following IRI is enough to prevent maladaptive repair and the development of CKD. Our findings highlight the importance of the early days of reperfusion, indicating that maladaptive responses can be reduced effectively following severe AKI. KEY POINTS: Physiological processes activated after acute kidney injury (AKI) can lead to maladaptive responses, causing nephron loss and fibrosis. Prophylactic renoprotection with resveratrol (RSV) has been described in experimental AKI, but its impact after AKI and for subsequent chronic kidney disease (CKD) remains unclear. In this study, we found that histological tubular injury persists 10 days after ischaemia-reperfusion injury and contributes to a failed repair phenotype in proximal tubular cells. Short-term RSV intervention influenced the post-ischaemic repair response and accelerated tubular recovery by reducing oxidative stress and mitochondrial damage. Furthermore, RSV targeted inflammation and profibrotic signalling during the maladaptive response, normalizing both processes. Resveratrol effectively prevented AKI-to-CKD transition even 5 months after the intervention. The study serves as a proof of concept, proposing RSV as a valuable candidate for further translational clinical studies to mitigate AKI-to-CKD transition.

Sex Bias in Prediction and Diagnosis of Cardiac Surgery Associated Acute Kidney Injury

Background

Female sex has been recognized as a risk factor for cardiac surgery associated acute kidney injury (CS-AKI). The current study sought to evaluate whether female sex is a risk factor for CS-AKI, or modifies the association of peri-operative change in serum creatinine with CS-AKI.

Methods

Observational study of adult patients undergoing cardiac surgery between 2000 and 2019 in a single U.S. center. The main variable of interest was registered patient sex, identified from electronic medical records. The main outcome was CS-AKI within 2 weeks of surgery.

Results

Of 58526 patients, 19353 (33%) were female; 12934 (22%) incurred AKI based on ≥ 0.3 mg/dL or ≥ 50% rise in serum creatinine (any AKI), 3320 (5.7%) had moderate to severe AKI, and 1018 (1.7%) required dialysis within 2 weeks of surgery. Female sex was associated with higher risk for AKI in models that were based on preoperative serum creatinine (OR, 1.35; 95% CI, 1.29-1.42), and lower risk with the use of estimated glomerular filtration, (OR, 0.90; 95% CI, 0.86-0.95). The risk for moderate to severe CS-AKI for a given immediate peri-operative change in serum creatinine was higher in female compared to male patients (p < .0001 and p < .0001 for non-linearity), and the association was modified by pre-operative kidney function (p < .0001 for interaction).

Conclusions

The association of patient sex with CS-AKI and its direction was dependent on the operational definition of pre-operative kidney function, and differential outcome misclassification due to AKI defined by absolute change in serum creatinine.

Transient inhibition of sodium-glucose cotransporter 2 after ischemia/reperfusion injury ameliorates chronic kidney disease

Sodium-glucose cotransporter 2 (SGLT2) inhibitor, dapagliflozin (Dapa), exhibited nephroprotective effects in patients with chronic kidney disease (CKD). We assessed the efficacy of short-term Dapa administration following acute kidney injury (AKI) in preventing CKD. Male Wistar rats were randomly assigned to Sham surgery, bilateral ischemia for 30 minutes (abbreviated as IR), and IR + Dapa groups. Daily treatment with Dapa was initiated just 24 hours after IR and maintained for only 10 days. Initially, rats were euthanized at this point to study early renal repair. After severe AKI, Dapa promptly restored creatinine clearance (CrCl) and significantly reduced renal vascular resistance compared with the IR group. Furthermore, Dapa effectively reversed the mitochondrial abnormalities, including increased fission, altered mitophagy, metabolic dysfunction, and proapoptotic signaling. To study this earlier, another set of rats was studied just 5 days after AKI. Despite persistent renal dysfunction, our data reveal a degree of mitochondrial protection. Remarkably, a 10-day treatment with Dapa demonstrated effectiveness in preventing CKD transition in an independent cohort monitored for 5 months after AKI. This was evidenced by improvements in proteinuria, CrCl, glomerulosclerosis, and fibrosis. Our findings underscore the potential of Dapa in preventing maladaptive repair following AKI, emphasizing the crucial role of early intervention in mitigating AKI long-term consequences.

Sustained activation of 12/15 lipoxygenase (12/15 LOX) contributes to impaired renal recovery post ischemic injury in male SHR compared to females

BACKGROUND

Acute kidney injury (AKI) due to ischemia-reperfusion (IR) is a serious and frequent complication in clinical settings, and mortality rates remain high. There are well established sex differences in renal IR, with males exhibiting greater injury following an ischemic insult compared to females. We recently reported that males have impaired renal recovery from ischemic injury vs. females. However, the mechanisms mediating sex differences in renal recovery from IR injury remain poorly understood. Elevated 12/15 lipoxygenase (LOX) activity has been reported to contribute to the progression of numerous kidney diseases. The goal of the current study was to test the hypothesis that enhanced activation of 12/15 LOX contributes to impaired recovery post-IR in males vs. females.

METHODS

13-week-old male and female spontaneously hypertensive rats (SHR) were randomized to sham or 30-minute warm bilateral IR surgery. Additional male and female SHR were randomized to treatment with vehicle or the specific 12/15 LOX inhibitor ML355 1 h prior to sham/IR surgery, and every other day following up to 7-days post-IR. Blood was collected from all rats 1-and 7-days post-IR. Kidneys were harvested 7-days post-IR and processed for biochemical, histological, and Western blot analysis. 12/15 LOX metabolites 12 and 15 HETE were measured in kidney samples by liquid chromatography-mass spectrometry (LC/MS).

RESULTS

Male SHR exhibited delayed recovery of renal function post-IR vs. male sham and female IR rats. Delayed recovery in males was associated with activation of renal 12/15 LOX, increased renal 12-HETE, enhanced endoplasmic reticulum (ER) stress, lipid peroxidation, renal cell death and inflammation compared to females 7-days post-IR. Treatment of male SHR with ML355 lowered levels of 12-HETE and resulted in reduced renal lipid peroxidation, ER stress, tubular cell death and inflammation 7-days post-IR with enhanced recovery of renal function compared to vehicle-treated IR male rats. ML355 treatment did not alter IR-induced increases in plasma creatinine in females, however, tubular injury and cell death were attenuated in ML355 treated females compared to vehicle-treated rats 7 days post-IR.

CONCLUSION

Our data demonstrate that sustained activation 12/15 LOX contributes to impaired renal recovery post ischemic injury in male and female SHR, although males are more susceptible on this mechanism than females.

Epidemiology and outcomes of post-AKI proteinuria

Background

Acute kidney injury (AKI) has been associated with increased risks of new-onset and worsening proteinuria. However, epidemiologic data for post-AKI proteinuria was still lacking. This study aimed to determine the incidence, risk factors and clinical correlations of post-AKI proteinuria among hospitalized patients.

Methods

This study was conducted in a multicenter cohort including patients aged 18-100 years with hospital-acquired AKI (HA-AKI) hospitalized at 19 medical centers throughout China. The primary outcome was the incidence of post-AKI proteinuria. Secondary outcomes included AKI recovery and kidney disease progression. The results of both quantitative and qualitative urinary protein tests were used to define post-AKI proteinuria. Cox proportional hazard model with stepwise regression was used to determine the risk factors for post-AKI proteinuria.

Results

Of 6206 HA-AKI patients without proteinuria at baseline, 2102 (33.9%) had new-onset proteinuria, whereas of 5137 HA-AKI with baseline proteinuria, 894 (17.4%) had worsening proteinuria after AKI. Higher AKI stage and preexisting CKD diagnosis were risk factors for new-onset proteinuria and worsening proteinuria, whereas treatment with renin-angiotensin system inhibitors was associated with an 11% lower risk of incident proteinuria. About 60% and 75% of patients with post-AKI new-onset and worsening proteinuria, respectively, recovered within 3 months. Worsening proteinuria was associated with a lower incidence of AKI recovery and a higher risk of kidney disease progression.

Conclusions

Post-AKI proteinuria is common and usually transient among hospitalized patients. The risk profiles for new-onset and worsening post-AKI proteinuria differed markedly. Worsening proteinuria after AKI was associated with adverse kidney outcomes, which emphasized the need for close monitoring of proteinuria after AKI.

JNK Signalling Regulates Self-Renewal of Proliferative Urine-Derived Renal Progenitor Cells via Inhibition of Ferroptosis

With a global increase in chronic kidney disease patients, alternatives to dialysis and organ transplantation are needed. Stem cell-based therapies could be one possibility to treat chronic kidney disease. Here, we used multipotent urine-derived renal progenitor cells (UdRPCs) to study nephrogenesis. UdRPCs treated with the JNK inhibitor-AEG3482 displayed decreased proliferation and downregulated transcription of cell cycle-associated genes as well as the kidney progenitor markers-SIX2, SALL1 and VCAM1. In addition, levels of activated SMAD2/3, which is associated with the maintenance of self-renewal in UdRPCs, were decreased. JNK inhibition resulted in less efficient oxidative phosphorylation and more lipid peroxidation via ferroptosis, an iron-dependent non-apoptotic cell death pathway linked to various forms of kidney disease. Our study is the first to describe the importance of JNK signalling as a link between maintenance of self-renewal and protection against ferroptosis in SIX2-positive renal progenitor cells.

The protective effect of H151, a novel STING inhibitor, in renal ischemia-reperfusion-induced acute kidney injury

Renal ischemia-reperfusion (RIR)-induced acute kidney injury (AKI) is a common renal functional disorder with high morbidity and mortality. Stimulator of interferon (IFN) genes (STING) is the cytosolic DNA-activated signaling pathway that mediates inflammation and injury. Our recent study showed that extracellular cold-inducible RNA-binding protein (eCIRP), a newly identified damage-associated molecular pattern, activates STING and exacerbates hemorrhagic shock. H151 is a small molecule that selectively binds to STING and inhibits STING-mediated activity. We hypothesized that H151 attenuates eCIRP-induced STING activation in vitro and inhibits RIR-induced AKI in vivo. In vitro, renal tubular epithelial cells incubated with eCIRP showed increased levels of IFN-β, STING pathway downstream cytokine, IL-6, tumor necrosis factor-α, and neutrophil gelatinase-associated lipocalin, whereas coincubation with eCIRP and H151 diminished those increases in a dose-dependent manner. In vivo, 24 h after bilateral renal ischemia-reperfusion, glomerular filtration rate was decreased in RIR-vehicle-treated mice, whereas glomerular filtration rate was unchanged in RIR-H151-treated mice. In contrast to sham, serum blood urea nitrogen, creatinine, and neutrophil gelatinase-associated lipocalin were increased in RIR-vehicle, but in RIR-H151, these levels were significantly decreased from RIR-vehicle. In contrast to sham, kidney IFN-β mRNA, histological injury score, and TUNEL staining were also increased in RIR-vehicle, but in RIR-H151, these levels were significantly decreased from RIR-vehicle. Importantly, in contrast to sham, in a 10-day survival study, survival decreased to 25% in RIR-vehicle, but RIR-H151 had a survival of 63%. In conclusion, H151 inhibits eCIRP-induced STING activation in renal tubular epithelial cells. Therefore, STING inhibition by H151 can be a promising therapeutic intervention for RIR-induced AKI.NEW & NOTEWORTHY Renal ischemia-reperfusion (RIR)-induced acute kidney injury (AKI) is a common renal functional disorder with a high morbidity and mortality rate. Stimulator of interferon genes (STING) is the cytosolic DNA-activated signaling pathway responsible for mediating inflammation and injury. Extracellular cold-inducible RNA-binding protein (eCIRP) activates STING and exacerbates hemorrhagic shock. H151, a novel STING inhibitor, attenuated eCIRP-induced STING activation in vitro and inhibited RIR-induced AKI. H151 shows promise as a therapeutic intervention for RIR-induced AKI.

Sexual dimorphism in acute myocardial infarction-induced acute kidney injury: cardiorenal deteriorating effects of ovariectomy in premenopausal female mice

Acute kidney injury (AKI) is a common complication of cardiovascular diseases (CVDs) in both males and females, increasing mortality rate substantially. Premenopausal females appear to be more protected, suggesting a potential protective role of female sex hormones. Here, we tested the hypothesis that ovariectomy (OVX) eliminates the beneficial effect of female sex on renal protection following acute myocardial infarction (MI). Seven days post-MI, both sexes exhibited worsened kidney function and a substantial decrease in total kidney NAD levels. Unlike MI female mice, MI males showed exacerbated morphological alterations with increased proinflammatory, proapoptotic, and profibrotic biomarkers. The expression of NAD+ biosynthetic enzymes NAMPT and NMRK-1 was increased in MI females only, while males showed a substantial increase in NAD+ consuming enzyme PARP-1. OVX did not eliminate the female-sex protection of glomerular morphology but was associated with swelling of proximal convoluted tubules with MI as in males. With OVX, MI females had enhanced proinflammatory cytokine release, and a further decrease in creatinine clearance and urine output was observed. Our findings suggest that MI induced AKI in both sexes with pre-menopausal female mice being more protected. Ovariectomy worsens aspects of AKI in females after MI, which may portend increased risk for development of chronic kidney disease.

Original research gender differences in recovering from cardiac and vascular surgery associated acute kidney injury: A six-year retrospective comparative study in Nigeria

Introduction

Gender differences exist in the demographic, clinical characteristic and outcome of patients with cardiac and vascular surgery (CVS) associated acute kidney injury (AKI).

Materials and Methods

This retrospective study had a total of 88 participants for which socio-demographic, clinical and laboratory (serum electrolyte, full blood count, urine analysis and urine volume, creatinine, and glomerular filtration rate) data of participants were taken preoperative and postoperative days 1, 7, and 30.

Results

A total of 88 (66 males and 22 females) participants were studied. Diseases of the heart valves were more common in females than males. The mean age of the participants was 65.9 ± 6.9 years, with males 65.1 ± 7.6 years and females 68.3 ± 8.4 years, P = 0.02. Before surgery, a significantly greater proportion of females had kidney dysfunction compared to males, P = 0.003. Valvular surgery and coronary bypass were the most common surgeries. The proportion of emergency surgeries and admissions <7 days were significantly higher in females than males, P = 0.04 and P = 0.02, respectively. Full recovering from AKI was significantly higher in males as partial recovery and death were significantly lower in them, P = 0.02. Of the 35 (39.8%) who had dialysis, 85.7% recovered fully, 5.7% became dialysis, and dependent while 8.6% died. The predictors of nonrecovery from CVS-AKI were female gender, elderly, preoperative kidney dysfunction and AKI stage 3.

Conclusion

Males with AKI were younger than the females. Valvular surgeries were most common. Background kidney dysfunction and advance age were risk factors for AKI. Postoperative, AKI was commoner in males who were more likely to recover full kidney function. Optimizing patient preparation could reduce the incidence of CVS-AKI.

Comorbidity, life-style factors and healthcare utilization in incident chronic kidney disease: sex-specific analyses of claims data

BACKGROUND

Chronic kidney disease (CKD) is common in aging men and women. In contrast to other European countries, Germany lacks CKD registries. The aim of this study was to determine the incidence of CKD stages 2-5 in men and women in Germany. Furthermore, differences between the sexes in terms of comorbidities, potentially inappropriate medications (PIM), and healthcare utilization were examined.

METHODS

In this retrospective observational study, claims data from members of a statutory health insurance fund aged 18 years or older with incident CKD between 2011 and 2018 were analyzed. Incident CKD was defined as having two confirmed diagnoses of CKD stages 2-5 from outpatient care or one primary or secondary diagnosis from inpatient care.

RESULTS

The age- and sex-standardized incidence of all CKD stages was 945/100 000 persons between 2011 and 2018. Incident CKD, especially stages 3 and 4, occurred more frequently in women, while the incidence of stages 2 and 5 was higher in men. While women visited their GP more frequently and were prescribed PIMs more often, men were more likely to visit a nephrologist and were more often hospitalized after the incident CKD diagnosis.

CONCLUSION

More awareness needs to be raised towards the early detection of CKD and the use of PIMs, especially in women. Improved care coordination is needed to avoid an overprovision of patients with uncomplicated incident stages and ensure that patients with advanced CKD stages get timely access to specialist care.

Dimorphic Response of Sex and Hospital-acquired Acute Kidney Injury

The risk of hospital-acquired acute kidney injury (HA-AKI) depends on a person's intrinsic susceptibility, the presence of risk factors, and on the type and extent of exposure to kidney insults. Older cohort studies have focused on male-only or mostly male populations, assuming a lower incidence of HA-AKI in women. Insufficient statistical power suggested that female sex was a shared susceptibility factor for HA-AKI. It was included as a risk factor in risk prediction models of HA-AKI. With the inclusion of women in clinical research studies, this presumption was challenged. Recent meta-analyses of sex-stratified studies showed that the risk for HA-AKI was significantly higher in men. These results suggested a protective role of female sex hormones. However, these studies were complicated by the inclusion of women across an age spectrum that includes the menopausal shift. Preliminary clinical and basic research data suggest that postmenopausal women lose their protection from HA-AKI. The number, size, and quality of reported clinical studies are low. There is an unmet need to characterize the susceptibility factor sex, to assess its clinical relevance and to evaluate renoprotection by sex hormone administration.

Persistent vascular congestion in male spontaneously hypertensive rats contributes to delayed recovery of renal function following ischemia-reperfusion compared to females

Acute kidney injury (AKI) is a serious and frequent clinical complication with mortality rates up to 80%. Vascular congestion in the renal outer medulla occurs early after ischemia reperfusion (IR) injury, and congestion has been linked to worsened outcomes following IR. There is evidence implicating both male sex and preexisting hypertension as risk factors for poor outcomes following IR. The present study tested the hypothesis that male spontaneously hypertensive rats (SHR) have greater vascular congestion and impaired renal recovery following renal IR vs. female SHR and normotensive male Sprague-Dawley rats (SD). 13 wk old male and female SHR and SD were subjected to sham surgery or 30 minutes of warm bilateral ischemia followed by reperfusion. Rats were euthanized 24 hours or 7 days post-IR. IR increased renal injury in all groups vs. sham controls at 24 hours. At 7 days post-IR, injury remained elevated only in male SHR. Histological examination of SD and SHR kidneys 24 hours post-IR showed vascular congestion in males and females. Vascular congestion was sustained only in male SHR 7 days post-IR. To assess the role of vascular congestion on impaired recovery following IR, additional male and female SHR were pretreated with heparin (200 U/kg) prior to IR. Heparin pre-treatment reduced IR-induced congestion and improved renal function in male SHR 7 days post-IR. Interestingly, preventing increases in BP in male SHR did not alter sustained vascular congestion. Our data demonstrate that IR-induced vascular congestion is a major driving factor for impaired renal recovery in male SHR.

Pericyte-mediated constriction of renal capillaries evokes no-reflow and kidney injury following ischaemia

Acute kidney injury is common, with ~13 million cases and 1.7 million deaths/year worldwide. A major cause is renal ischaemia, typically following cardiac surgery, renal transplant or severe haemorrhage. We examined the cause of the sustained reduction in renal blood flow ('no-reflow'), which exacerbates kidney injury even after an initial cause of compromised blood supply is removed. Adult male Sprague-Dawley rats, or NG2-dsRed male mice were used in this study. After 60 min kidney ischaemia and 30-60 min reperfusion, renal blood flow remained reduced, especially in the medulla, and kidney tubule damage was detected as Kim-1 expression. Constriction of the medullary descending vasa recta and cortical peritubular capillaries occurred near pericyte somata, and led to capillary blockages, yet glomerular arterioles and perfusion were unaffected, implying that the long-lasting decrease of renal blood flow contributing to kidney damage was generated by pericytes. Blocking Rho kinase to decrease pericyte contractility from the start of reperfusion increased the post-ischaemic diameter of the descending vasa recta capillaries at pericytes, reduced the percentage of capillaries that remained blocked, increased medullary blood flow and reduced kidney injury. Thus, post-ischaemic renal no-reflow, contributing to acute kidney injury, reflects pericytes constricting the descending vasa recta and peritubular capillaries. Pericytes are therefore an important therapeutic target for treating acute kidney injury.

Sex Differences in Acute Kidney Injury

Female sex confers renoprotection in chronic progressive kidney disease. It is less well recognized that sexual dimorphism also is evident in the development of ischemic and nephrotoxic acute kidney injury (AKI). Animal studies consistently have shown that female sex protects against the development of renal injury in experimental models of ischemic AKI. However, the consensus opinion is that in human beings, female sex is an independent risk factor for AKI. Based on a systematic review of experimental and clinical literature, we present data to support the conclusion that, contrary to consensus opinion, it is male sex, not female sex, that is associated with the development of AKI.

Supplemental hydrogen sulfide in models of renal transplantation after cardiac death

Background:

The increasing use of kidneys from donations after cardiac death (DCD) for renal transplantation is hindered by negative outcomes owing to organ injury after prolonged warm and cold ischemia–reperfusion. Recently, hydrogen sulfide (H₂S) has shown cytoprotective effects against ischemia–reperfusion injury; however, its effectiveness in the context of DCD renal transplantation is unknown.

Methods:

We tested a novel 30-day in vivo syngeneic murine model of DCD renal transplantation, in which the donor kidney was clamped for 30 minutes and stored for 18 hours in cold University of Wisconsin (UW) solution or UW with 150 μM sodium hydrogen sulfide (UW + NaHS) before transplantation. We also tested a 7-day in vivo porcine model of DCD renal autotransplantation, in which the left kidney was clamped for 60 minutes and preserved for 24 hours using hypothermic perfusion with UW or UW + 150 μM NaHS before autotransplantation. We collected blood and urine samples periodically, and collected kidney samples at the end point for histopathology and quantitative reverse transcription polymerase chain reaction.

Results:

Rats that received H₂S-treated kidneys showed significantly higher survival, faster recovery of graft function and significantly lower acute tubular necrosis than controls. Pig kidneys perfused with UW + NaHS showed significantly higher renal blood flow and lower renal resistance than control kidneys after 24 hours of perfusion. After autotransplantation, pigs that received H₂S-treated kidneys showed significantly lower serum creatinine on days 1 and 7 after transplantation. Rat and pig kidneys treated with H₂S also showed more protective gene expression profiles than controls.

Conclusion:

Our findings support the potential use of H₂S-supplemented UW solution during cold storage as a novel and practical means to improve DCD graft survival and function.

Neuroimmunoendocrine Link Between Chronic Kidney Disease and Olfactory Deficits

Chronic kidney disease (CKD) is a multifactorial pathology that progressively leads to the deterioration of metabolic functions and results from deficient glomerular filtration and electrolyte imbalance. Its economic impact on public health is challenging. Mexico has a high prevalence of CKD that is strongly associated with some of the most common metabolic disorders like diabetes and hypertension. The gradual loss of kidney functions provokes an inflammatory state and endocrine alterations affecting several systems. High serum levels of prolactin have been associated with CKD progression, inflammation, and olfactory function. Also, the nutritional status is altered due to impaired renal function. The decrease in calorie and protein intake is often accompanied by malnutrition, which can be severe at advanced stages of the disease. Nutrition and olfactory functioning are closely interconnected, and CKD patients often complain of olfactory deficits, which ultimately can lead to deficient food intake. CKD patients present a wide range of deficits in olfaction like odor discrimination, identification, and detection threshold. The chronic inflammatory status in CKD damages the olfactory epithelium leading to deficiencies in the chemical detection of odor molecules. Additionally, the decline in cognitive functioning impairs the capacity of odor differentiation. It is not clear whether peritoneal dialysis and hemodialysis improve the olfactory deficits, but renal transplants have a strong positive effect. In the present review, we discuss whether the olfactory deficiencies caused by CKD are the result of the induced inflammatory state, the hyperprolactinemia, or a combination of both.

Sex Differences in Renal Function: Participation of Gonadal Hormones and Prolactin

Kidney pathophysiology is influenced by gender. Evidence suggests that kidney damage is more severe in males than in females and that sexual hormones contribute to this. Elevated prolactin concentration is common in renal impairment patients and is associated with an unfavorable prognosis. However, PRL is involved in the osmoregulatory process and promotes endothelial proliferation, dilatation, and permeability in blood vessels. Several proteinases cleavage its structure, forming vasoinhibins. These fragments have antagonistic PRL effects on endothelium and might be associated with renal endothelial dysfunction, but its role in the kidneys has not been enough investigated. Therefore, the purpose of this review is to describe the influence of sexual dimorphism and gonadal hormones on kidney damage, emphasizing the role of the hormone prolactin and its cleavage products, the vasoinhibins.

Vegfa promoter gene hypermethylation at HIF1α binding site is an early contributor to CKD progression after renal ischemia

Chronic hypoxia is a major contributor to Chronic Kidney Disease (CKD) after Acute Kidney Injury (AKI). However, the temporal relation between the acute insult and maladaptive renal response to hypoxia remains unclear. In this study, we analyzed the time-course of renal hemodynamics, oxidative stress, inflammation, and fibrosis, as well as epigenetic modifications, with focus on HIF1α/VEGF signaling, in the AKI to CKD transition. Sham-operated, right nephrectomy (UNx), and UNx plus renal ischemia (IR + UNx) groups of rats were included and studied at 1, 2, 3, or 4 months. The IR + UNx group developed CKD characterized by progressive proteinuria, renal dysfunction, tubular proliferation, and fibrosis. At first month post-ischemia, there was a twofold significant increase in oxidative stress and reduction in global DNA methylation that was maintained throughout the study. Hif1α and Vegfa expression were depressed in the first and second-months post-ischemia, and then Hif1α but not Vegfa expression was recovered. Interestingly, hypermethylation of the Vegfa promoter gene at the HIF1α binding site was found, since early stages of the CKD progression. Our findings suggest that renal hypoperfusion, inefficient hypoxic response, increased oxidative stress, DNA hypomethylation, and, Vegfa promoter gene hypermethylation at HIF1α binding site, are early determinants of AKI-to-CKD transition.

Sex Differences in Kidney Function and Metabolism Assessed Using Hyperpolarized [1-13C]Pyruvate Interleaved Spectroscopy and Nonspecific Imaging

Metabolic sex differences have recently been shown to be particularly important in tailoring treatment strategies. Sex has a major effect on fat turnover rates and plasma lipid delivery in the body. Differences in kidney structure and transporters between male and female animals have been found. Here we investigated sex-specific renal pyruvate metabolic flux and whole-kidney functional status in age-matched healthy Wistar rats. Blood oxygenation level–dependent and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) were used to assess functional status. Hyperpolarized [1-¹³C]pyruvate was used to assess the metabolic differences between male and female rats. Female rats had a 41% ± 3% and 41% ± 5% lower absolute body and kidney weight, respectively, than age-matched male rats. No difference was seen between age-matched male and female rats in the kidney-to-body weight ratio. A 56% ± 11% lower lactate production per mL/100 mL/min was found in female rats than in age-matched male rats measured by hyperpolarized magnetic resonance and DCE MRI. Female rats had a 33% ± 11% higher glomerular filtration rate than age-matched male rats measured by DCE MRI. A similar renal oxygen tension (T2*) was found between age-matched male and female rats as shown by blood oxygenation level–dependent MRI. The results were largely independent of the pyruvate volume and the difference in body weight. This study shows an existing metabolic difference between kidneys in age-matched male and female rats, which indicates that sex differences need to be considered when performing animal experiments.

Tubular epithelial cells derived-exosomes containing CD26 protects mice against renal ischemia/reperfusion injury by maintaining proliferation and dissipating inflammation

Ischemia-reperfusion injury (IR) is the leading cause of acute kidney injury (AKI). No effective drugs to treat IR-related AKI are currently available. Recent pre-clinical trials have evaluated the therapeutic potential of extracellular vesicles-exosomes to chronic kidney disease. Here, we found exosomes derived from the tubular epithelial cell in IR condition (Exo^IR) enriched CD26, compared with control (Exo^Normal). Tracking exosomes in vivo certified tubular epithelial cell uptake exosomes. We have isolated exosomes with overexpression of CD26 (Exo^CD26+) from culture media from tubular epithelial cell line transferred by adenovirus vectors. After administration of exosomes (100 mg) or bovine serum albumin (BSA, equivalent protein control) in IR or sham operation mice after 72 h via tail vein injection, the renal function impairment and histology injury were relived in mice receiving Exo^CD26+. Immunofluorescence staining with proliferating cell nuclear antigen revealed Exo^CD26+ recovered proliferation of cells partly after IR injury. Cell cycle modulator, p53 and p21 were upregulated in IR mice receiving BSA control, Exo^Normal, and Exo^IR. Exo^CD26+ significantly blunt this protein upregulation. Inflammatory cell infiltration and chemokine receptor (CXCR4) were dissipated in IR mice receiving Exo^CD26+. Downstream chemokine of CXCR4, stromal derived factor-1 (SDF1) also decreased after administration of Exo^CD26+ in IR mice. Finally, Exo^CD26+ suppressed inundant collagenⅠ expression in IR kidney. In conclusion, Tubular epithelial cells derived-exosomes containing CD26 might be one of the therapy modes for IR-AKI by maintaining proliferation and dissipating inflammation.

Adverse Maternal and Fetal Outcomes in a Novel Experimental Model of Pregnancy after Recovery from Renal Ischemia-Reperfusion Injury

BACKGROUND

Recent clinical studies report that women with a history of AKI have an increased incidence of maternal and fetal adverse outcomes during pregnancy, despite fully recovering renal function prior to conception. The mechanisms contributing to such adverse outcomes in pregnancy after AKI are not yet understood.

METHODS

To develop a rodent model to investigate fetal and maternal outcomes in female animals with a history of AKI, we used ischemia-reperfusion injury as an experimental model of AKI in female Sprague Dawley rats. The 12-week-old animals underwent warm bilateral ischemia-reperfusion surgery involving clamping of both renal arteries for 45 minutes or sham surgery (control). Rats were allowed to recover for 1 month prior to mating. Recovery from ischemia-reperfusion injury was confirmed by measurements of plasma creatinine and urinary protein excretion. We assessed maternal and fetal outcomes during late pregnancy on gestational day 20.

RESULTS

After recovery from ischemia-reperfusion injury, compared with healthy sham-surgery controls, dams exhibited pregnancy-induced renal insufficiency with increases in plasma creatinine and urea, along with increased urinary protein excretion. Additionally, recovered ischemia-reperfusion dams experienced worse fetal outcomes compared with controls, with intrauterine growth restriction leading to higher rates of fetal demise and smaller pups.

CONCLUSIONS

In this rat model, despite biochemical resolution of ischemia-reperfusion injury, subsequent pregnancy resulted in maternal renal insufficiency and significant impairments in fetal growth. This mirrors findings in recent reports in the clinical population, indicating that this model may be a useful tool to further explore the alterations in kidney function after AKI in women.

Sex differences in renal mitochondrial function: a hormone-gous opportunity for research

Sex differences (biological distinctions between males and females) present a complex interplay of genetic, developmental, biological, and environmental factors. More and more studies are shedding light on the importance of sex differences in normal physiology and susceptibility to cancer, cardiovascular and renal conditions, and neurodegenerative diseases. This mini-review is devoted to the role of sex dimorphisms in renal function, with a focus on the distinctions between male and female mitochondria. Here, we cover the aspects of renal mitochondrial bioenergetics where sex differences have been reported to date, for instance, biogenesis, reactive oxygen species production, and oxidative stress. Special attention is devoted to the effects of sex hormones, such as estrogen and testosterone, on mitochondrial bioenergetics in the kidney in physiology and pathophysiology.

Gene-environment interaction in chronic kidney disease among people with type 2 diabetes from The Malaysian Cohort project: a case-control study

AIM

To examine the possible gene-environment interactions between 32 single nucleotide polymorphisms and environmental factors that could modify the probability of chronic kidney disease.

METHODS

A case-control study was conducted involving 600 people with type 2 diabetes (300 chronic kidney disease cases, 300 controls) who participated in The Malaysian Cohort project. Retrospective subanalysis was performed on the chronic kidney disease cases to assess chronic kidney disease progression from the recruitment phase. We genotyped 32 single nucleotide polymorphisms using mass spectrometry. The probability of chronic kidney disease and predicted rate of newly detected chronic kidney disease progression were estimated from the significant gene-environment interaction analyses.

RESULTS

Four single nucleotide polymorphisms (eNOS rs2070744, PPARGC1A rs8192678, KCNQ1 rs2237895 and KCNQ1 rs2283228) and five environmental factors (age, sex, smoking, waist circumference and HDL) were significantly associated with chronic kidney disease. Gene-environment interaction analyses revealed significant probabilities of chronic kidney disease for sex (PPARGC1A rs8192678), smoking (eNOS rs2070744, PPARGC1A rs8192678 and KCNQ1 rs2237895), waist circumference (eNOS rs2070744, PPARGC1A rs8192678, KCNQ1 rs2237895 and KCNQ1 rs2283228) and HDL (eNOS rs2070744 and PPARGC1A rs8192678). Subanalysis indicated that the rate of newly detected chronic kidney disease progression was 133 cases per 1000 person-years (95% CI: 115, 153), with a mean follow-up period of 4.78 (SD 0.73) years. There was a significant predicted rate of newly detected chronic kidney disease progression in gene-environment interactions between KCNQ1 rs2283228 and two environmental factors (sex and BMI).

CONCLUSIONS

Our findings suggest that the gene-environment interactions of eNOS rs2070744, PPARGC1A rs8192678, KCNQ1 rs2237895 and KCNQ1 rs2283228 with specific environmental factors could modify the probability for chronic kidney disease.

Association of gender, age, and race on renal outcomes and mortality in patients with severe sepsis and septic shock

BACKGROUND

The association of age, gender and race with renal outcomes in patients with severe sepsis and septic shock (SEP) is not completely elucidated. We aimed to shed light on these relationships.

METHODS

We performed a retrospective cohort study of hospitalized patients in the USA discharged between January 1st, 2005 and December 31st, 2014 using the National Inpatient Sample. We adjusted analyses using the Charlson comorbidity index.

RESULTS

65,772,607 records were included of which 1,064,790 had SEP. There were 60% female and 12% African American (AA). The incidence of SEP was 1.6% and patients with SEP were older, had more AA and less females. Acute kidney injury (AKI) and mortality among patients with SEP were 62% and 30.7% respectively. AA race was associated with increased risk of SEP, AKI and dialysis, (OR = 1.12, 1.25 and 1.7 respectively, all p < 0.001). Female gender was associated with lower risk of all measured outcomes with odds ratios ranging from 0.65 to 0.78 (p < 0.001). Increasing age was associated with a higher risk of all outcomes except for dialysis.

CONCLUSION

Female gender is associated with a lower risk of poor renal outcomes and death among patients with SEP, while AA race places patients at higher risk of poor outcomes in that setting. Increasing age is generally associated with adverse outcomes.

Specific expression of survivin, SOX9, and CD44 in renal tubules in adaptive and maladaptive repair processes after acute kidney injury in rats

Acute kidney injury (AKI) is thought to be a reversible condition; however, growing evidence has suggested that AKI may be associated with subsequent development of chronic kidney disease. Although renal tubules have intrinsic regeneration capacity, disruption of the regeneration mechanisms leads to irreversible interstitial fibrosis. In this study, we investigated immunohistochemical markers of renal tubules in adaptive and maladaptive repair processes to predict AKI reversibility. Histopathological analysis demonstrated that regenerative tubules and dilated tubules were observed in the kidneys of AKI model rats after ischemia/reperfusion (I/R). Regenerative tubules gradually redifferentiated after I/R, whereas dilated tubules exhibited no tendency for redifferentiation. In fibrotic areas of the kidney in renal fibrosis model rats subjected to I/R, renal tubules were dilated or atrophied. There results suggested that the histopathological features of renal tubules in the maladaptive repair were dilation or atrophy. From microarray data of regenerative tubules, survivin, SOX9, and CD44 were extracted as candidate markers. Immunohistochemical analysis demonstrated that survivin and SOX9 were expressed in regenerative tubules, whereas SOX9 was also detected in renal tubules in fibrotic areas. These findings indicated that survivin and SOX9 contributed to renal tubular regeneration, whereas sustained SOX9 expression may be associated to fibrosis. CD44 was expressed in dilated tubules in the kidneys of AKI model rats and in the tubules of fibrotic areas of renal fibrosis model rats, suggesting that CD44 was expressed in renal tubules in maladaptive repair. Thus, these factors could be useful markers for detecting disruption of the regenerative mechanisms of renal tubules.

Sex-dependent mechanisms involved in renal tolerance to ischemia-reperfusion: Role of inflammation and histone H3 citrullination

Ischemia-reperfusion (I/R) injury, an inevitable result of kidney transplantation, triggers early inflammatory events that affect graft viability. Evidence from human transplantation and preclinical models of I/R suggests that a female hormonal environment positively influences the ability to recover from ischemic injury. However, the mechanisms behind these effects remain mostly unexplored. Here, we studied the influence of sex on pro-inflammatory mediators involved in the pathophysiology of acute I/R injury in male, female, and female ovariectomized (OVX) Wistar rats that underwent unilateral renal ischemia for 45 min, followed by 24 h of reperfusion. We found improved renal function, reduced cytokine expression, and decreased infiltration of myeloperoxidase-positive cells in females after I/R, when compared to their male and female OVX counterparts. Remarkably, citrullination of histone H3 was exacerbated in serum and renal tubules of females after I/R. In contrast, we observed lower levels of citrullinated histone H3 in male and female OVX rats in response to I/R, mostly in neutrophil extracellular traps. Our results demonstrate that female sex promotes renal I/R tolerance by attenuating pro-inflammatory mediators involved in I/R-induced damage.

Gender differences in the susceptibility of hospital-acquired acute kidney injury: more questions than answers

Hospital-acquired acute kidney injury (HA-AKI) is a heterogeneous renal syndrome which occurs in different clinical settings. It is characterized by multiple aetiologies, various pathogeneses and unpredictable outcomes. HA-AKI, once predominantly viewed as a self-limited and reversible short-term condition, is now recognized as a harbinger for chronic kidney disease and a cause of long-term morbidity with an increased risk of cardiovascular, renal and cancer mortality. Recent clinical studies contradict the generally held belief that female sex is a risk factor for HA-AKI. They show, consistent with basic research performed with experimental models of AKI, that only male sex is associated with HA-AKI. The presence of testosterone, more likely than the absence of estrogen, plays a critical role in sex differences in the susceptibility of ischemia/reperfusion kidney injury. The conflicting data in epidemiological studies related to sex as susceptibility variable for human AKI, underscore the need for more rigorous, well designed observational studies taking into account the menopausal status and hormone therapy.

Estrogen-related mechanisms in sex differences of hypertension and target organ damage

Hypertension (HTN) is a primary risk factor for cardiovascular (CV) events, target organ damage (TOD), premature death and disability worldwide. The pathophysiology of HTN is complex and influenced by many factors including biological sex. Studies show that the prevalence of HTN is higher among adults aged 60 and over, highlighting the increase of HTN after menopause in women. Estrogen (E2) plays an important role in the development of systemic HTN and TOD, exerting several modulatory effects. The influence of E2 leads to alterations in mechanisms regulating the sympathetic nervous system, renin-angiotensin-aldosterone system, body mass, oxidative stress, endothelial function and salt sensitivity; all associated with a crucial inflammatory state and influenced by genetic factors, ultimately resulting in cardiac, vascular and renal damage in HTN. In the present article, we discuss the role of E2 in mechanisms accounting for the development of HTN and TOD in a sex-specific manner. The identification of targets with therapeutic potential would contribute to the development of more efficient treatments according to individual needs.

Protective effect of genistein in a rat model of ischemic acute kidney injury

BACKGROUND

This study determined the possible anti-inflammatory and antioxidant renal protective effect of genistein, a soy isoflavone, against kidney damage and functional disorders following renal ischemia/reperfusion (I/R) in male rats.

MATERIALS AND METHODS

The animals were dedicated to five groups (n = 7 per group): Sham, Sham + Geni (genistein, 15 mg/kg in 1 ml 1% DMSO, i.p.), Sham + DMSO (1 ml 1% DMSO, i.p.), I/R (bilateral renal ischemia for 45 min followed by 24 h reperfusion), I/R + Geni (genistein, 15 mg/kg). 24-h urine samples, blood and tissue samples of the kidney were collected at the end of 24 h reperfusion period.

RESULTS

Compared to sham, sham + Geni and sham + DMSO groups, IR injury (IRI) ended in kidney dysfunction (decreased creatinine clearance, and increased fractional excretion of sodium), increased levels of malondialdehyde, decreased activities of antioxidant enzymes (superoxide dismutase, gluthatione peroxidase, and catalase), increased gene expression levels of TLR4 (Toll-like receptor 4) and TNF-α (tumor necrosis factor-alpha), as well as histological damages in kidney tissue. Genistein administration decreased all the changes. Therefore, genistein apparently protects the kidney against IRI by mitigating both oxidative stress and inflammation. The antioxidant and anti-inflammatory properties of genistein probably exert important roles in improving functional disorders and offer renal protection against IRI.

Impact of gender and gender disparities in patients with kidney disease

PURPOSE OF REVIEW

Despite evidence of gender-specific differences in epidemiology and outcomes in all stages of chronic kidney disease (CKD), most studies ignore the issue of gender. This review addresses this knowledge gap by evaluating data on gender disparity in this population.

RECENT FINDINGS

Population-based studies indicate a higher prevalence of CKD in women; however, there are fewer women on renal replacement therapy than men. Men may progress to end-stage kidney disease more rapidly. Gender differences in rates of CKD progression may be influenced by potential antifibrotic and antiapoptotic effects of estrogen or proinflammatory deleterious effects of testosterone. Women are referred later for kidney replacement therapy and receive fewer arteriovenous fistulas than men receive, irrespective of race. Women are also less likely to receive kidney transplants as compared with men but are more likely to donate a kidney.

SUMMARY

Recommendations for medical management of CKD patients are currently made in a gender-blind manner, despite the fact that women have differing underlying physiology. Addressing gender differences and disparities is an important and overlooked area in the care of patients with kidney disease.

Resilience to acute kidney injury in offspring of maternal protein restriction

Protein restriction (PR) during pregnancy induces morphofunctional alterations related to deficient nephrogenesis. We studied the renal functional and morphological significance of PR during pregnancy and/or lactation in adult male rat offspring and the repercussions on acute kidney injury (AKI) severity. Female rats were randomly assigned to the following groups: control diet during pregnancy and lactation (CC), control diet during pregnancy and PR diet during lactation (CR), PR during pregnancy and control diet during lactation (RC), and PR during pregnancy and lactation (RR). Three months after birth, at least 12 male offspring of each group randomly underwent either bilateral renal ischemia for 45 min [ischemia-reperfusion (IR)] or sham surgery. Thus, eight groups were studied 24 h after reperfusion: CC, CC + IR, CR, CR + IR, RC, RC + IR, RR, and RR + IR. Under basal conditions, the CR, RC, and RR groups exhibited a significant reduction in nephron number that was associated with a reduction in renal blood flow. Glomerular hyperfiltration was present as a compensatory mechanism to maintain normal renal function. mRNA levels of several vasoactive, antioxidant, and anti-inflammatory molecules were decreased. After IR, renal function was similarly reduced in all of the studied groups. Although all of the offspring from maternal PR exhibited renal injury, the magnitude was lower in the RC and RR groups, which were associated with faster renal blood flow recovery, differential vasoactive factors, and hypoxia-inducible factor-1α signaling. Our results show that the offspring from maternal PR are resilient to AKI induced by IR that was associated with reduced tubular injury and a differential hemodynamic response.

Testosterone and Zinc Supplementations on Renal Ischemia-Reperfusion Injury in Orchiectomized Rats

Background

Renal ischemia-reperfusion (IR) injury has numerous deleterious effects on the kidney function. An experimental investigation was conducted to determine the possible protective role of testosterone (TES) and zinc (Zn) supplementations on the kidney function after IR injury in orchiectomized rats.

Methods

Orchiectomized rats (n = 32) were divided into the five groups as sham operated (Group 1), IR (Group 2), IR pretreatment with TES (IR + TES, Group 3), Zn (IR + Zn, Group 4), and TES + Zn (IR + TES + Zn, Group 5). Twenty-four hours' post-IR injury, the animals were sacrificed and the required parameters were measured.

Results

The results revealed that there were not any significant difference in serum levels of creatinine (Cr), nitrite and malondialdehyde (MDA), Cr clearance (ClCr), renal sodium (Na) load, and percentage of Na excretion (ENa%) between sham and IR groups. The pretreatment with TES and Zn either alone or combine did not alter the serum levels of Cr, nitrite and MDA, and ClCr, Na load, and ENa%. However, pretreatment with Zn, TES, or combined altered kidney weight, kidney tissue levels of nitrite and MDA, and urine flow in IR groups.

Conclusions

The orchiectomy itself performed protective effect against renal IR injury. However, pretreatment with Zn or TES may not alter kidney function against renal IR in orchiectomized rats.

Spironolactone reduces oxidative stress in living donor kidney transplantation: a randomized controlled trial

Mineralocorticoid receptor antagonism prevents acute kidney injury induced by ischemia-reperfusion in rodent and pig preclinical models. In a pilot study, we showed that spironolactone (25 mg) reduced oxidative stress after 5 days of kidney transplant (KT). In the present study, we investigated the effects of higher doses (50 and 100 mg) of spironolactone on kidney function, tubular injury markers, and oxidative stress in living donor KT recipients. We included KT recipients aged 18 yr or older who received immunosuppression therapy with IL-2 receptor antagonist, mycophenolate mofetil, corticosteroids, and tacrolimus with negative cross-match, and compatible blood group. Patients were randomized to receive placebo ( n = 27), spironolactone (50 mg, n = 25), or spironolactone (100 mg, n = 25). Treatment was given from 3 days before and up to 5 days after KT. Serum creatinine, K+, urine neutrophil gelatinase-associated lipocalin-2, heat shock protein 72, and 8-hydroxy-2-deoxyguanosine levels were assessed. As expected, kidney function was improved after KT. Serum K+ remained in the normal range along the study. There was no significant effect of spironolactone on urinary neutrophil gelatinase-associated lipocalin-2 levels, whereas the increase in urinary heat shock protein 72 levels tended to be less intense in the 100 mg spironolactone-treated group ( P = 0.054). In the placebo-treated group, urinary 8-hydroxylated-guanosine levels increased on days 3 and 5 after transplantation. This effect was prevented in patients that received spironolactone. In conclusion, spironolactone reduces the acute increase in urinary oxidative stress in living donor KT recipients.

Opioids Preconditioning Upon Renal Function and Ischemia-Reperfusion Injury: A Narrative Review

Kidneys have an important role in regulating water volume, blood pressure, secretion of hormones and acid-base and electrolyte balance. Kidney dysfunction derived from acute injury can, under certain conditions, progress to chronic kidney disease. In the late stages of kidney disease, treatment is limited to replacement therapy: Dialysis and transplantation. After renal transplant, grafts suffer from activation of immune cells and generation of oxidant molecules. Anesthetic preconditioning has emerged as a promising strategy to ameliorate ischemia reperfusion injury. This review compiles some significant aspects of renal physiology and discusses current understanding of the effects of anesthetic preconditioning upon renal function and ischemia reperfusion injury, focusing on opioids and its properties ameliorating renal injury. According to the available evidence, opioid preconditioning appears to reduce inflammation and reactive oxygen species generation after ischemia reperfusion. Therefore, opioid preconditioning represents a promising strategy to reduce renal ischemia reperfusion injury and, its application on current clinical practice could be beneficial in events such as acute renal injury and kidney transplantation.

Reduced endothelial nitric oxide synthase activation contributes to cardiovascular injury during chronic kidney disease progression

Major cardiovascular events are a common complication in patients with chronic kidney disease (CKD). Endothelial dysfunction can contribute to the cardiovascular injury observed in CKD. Here, we used a rat model of acute kidney injury to CKD transition to investigate heart alterations in the pathway activating endothelial nitric oxide synthase (eNOS) and its impact on the cardiac injury observed during CKD progression. Fifty male Wistar rats were subjected to sham surgery ( n = 25) or bilateral renal ischemia-reperfusion (IR-CKD) for 45 min ( n = 25). Rats were studied on a monthly basis up to 5 mo ( n = 5). In another set of sham and IR-CKD rats, l-arginine was administered starting on the third month after renal ischemia. CKD development and cardiac alterations were monitored in all groups. CKD was characterized by a progressive increase in proteinuria and renal dysfunction that was evident after the fifth month of followup. Heart hypertrophy was observed starting on the fourth month after ischemia-reperfusion. There was a significant increase in brain natriuretic peptide levels. In the heart, IR-CKD rats had increased eNOS phosphorylation at threonine 495 and reduced eNOS-heat shock protein-90α interactions. l-Arginine administration prevented the heart alterations observed during CKD and increased eNOS coupling/dimerization and activation. In summary, CKD progression is accompanied by cardiac hypertrophy, fibrosis, oxidative stress, and increased brain natriuretic peptide levels. These alterations were associated with limited eNOS activation in the heart, which may result in reduced nitric oxide bioavailability and contribute to cardiac injury during CKD.

SerpinA3 in the Early Recognition of Acute Kidney Injury to Chronic Kidney Disease (CKD) transition in the rat and its Potentiality in the Recognition of Patients with CKD

Recognizing patients at early phases of chronic kidney disease (CKD) is difficult, and it is even more challenging to predict acute kidney injury (AKI) and its transition to CKD. The gold standard to timely identify renal fibrosis is the kidney biopsy, an invasive procedure not usually performed for this purpose in clinical practice. SerpinA3 was identified by high-resolution-mass-spectrometry in urines from animals with CKD. An early and progressive elevation of urinary SerpinA3 (uSerpinA3) was observed during the AKI to CKD transition together with SerpinA3 relocation from the cytoplasm to the apical tubular membrane in the rat kidney. uSerpinA3/alpha-1-antichymotrypsin was significantly increased in patients with CKD secondary to focal and segmental glomerulosclerosis (FSGS), ANCA associated vasculitis (AAV) and proliferative class III and IV lupus nephritis (LN). uSerpinA3 levels were independently and positively associated with renal fibrosis. In patients with class V LN, uSerpinA3 levels were not different from healthy volunteers. uSerpinA3 was not found in patients with systemic inflammatory diseases without renal dysfunction. Our observations suggest that uSerpinA3 can detect renal fibrosis and inflammation, with a particular potential for the early detection of AKI to CKD transition and for the differentiation among lupus nephritis classes III/IV and V.

Pirfenidone prevents acute kidney injury in the rat

Background

Pirfenidone is an orally active drug used for the treatment of idiopathic pulmonary fibrosis to slow loss of lung function; it acts mainly through an antifibrotic effect but also possesses antioxidant and anti-inflammatory properties. We assessed the effect of prophylactic administration of pirfenidone on acute kidney injury due to bilateral renal ischemia.

Methods

Eighteen rats were included and divided in: 1) sham-operated rats (S), 2) rats underwent bilateral renal ischemia for 20 min (I/R), and 3) rats treated with pirfenidone 700 mg/kg/day 24 h before surgery and subjected to bilateral renal ischemia for 20 min (I/R + PFN). All the rats were euthanized and studied 24 h after renal reperfusion.

Results

As was expected, the I/R group exhibited a significant reduction in creatinine clearance, urinary output and renal blood flow, as well as extensive tubular injury. These alterations were associated with a significant decrease in urinary excretion of nitrites and nitrates (UNO₂/NO₃V). In the I/R + PFN group, recovery of renal function and UNO₂/NO₃V was observed, together with lesser histological signs of tubular injury compared to the I/R group.

Conclusions

This study shows that prophylactic administration of pirfenidone prevented acute kidney injury due to bilateral ischemia in the rat. Recovery of NO production appears to be one of the mechanism of pirfenidone renoprotective effect. Our findings suggest that pirfenidone is a promising drug to reduce renal injury induced by I/R.

The association between intraoperative urine output and postoperative acute kidney injury differs between partial and radical nephrectomy

We sought to investigate the association between intraoperative urine output and postoperative acute kidney injury (AKI) in patients undergoing radical and partial nephrectomy. We retrospectively reviewed data of 742 patients. Postoperative AKI was defined by the Kidney Disease: Improving Global Outcomes criteria. The relationship between intraoperative urine output and the risk of AKI was evaluated by multivariable logistic regression analysis in radical and partial nephrectomy, separately. Minimum P-value approach was used to find the optimal threshold of intraoperative oliguria associated with the risk of AKI. The incidence of AKI was 14.4% (67/466) after partial nephrectomy and 57.6% (159/276) after radical nephrectomy. For partial nephrectomy, multivariable analysis showed that renal ischemic time, operation time, open surgery and intraoperative transfusion were significantly associated with AKI. For radical nephrectomy, history of hypertension, baseline glomerular filtration rate and intraoperative mean urine output were significantly associated with AKI. Intraoperative mean urine output during radical nephrectomy was associated with AKI after radical nephrectomy, while not after partial nephrectomy. Mean urine output <1.0 mL/kg/h was determined to be an optimal cutoff of AKI after radical nephrectomy. Intraoperative oliguria may have different clinical implication for AKI between partial and radical nephrectomy.

Sex differences in the response to dietary restriction in rodents

Dietary restriction (DR) remains the most reproducible and consistent laboratory intervention to extend lifespan and improve health in mammals. DR has been primarily characterized in males due to issues of cost, perceived heightened variability amongst females, and the misconception that the reproductive system is the only important difference between sexes in mammals. In reality, existing data point to clear sex differences in mammalian responses to DR. Here we discuss recent advances in our understanding of sex differences in the responses to DR in rodent models.