Female sex reduces the risk of hospital-associated acute kidney injury: a meta-analysis

Effects of 24-hour urine-output trajectories on the risk of acute kidney injury in critically ill patients with cirrhosis: a retrospective cohort analysis

BACKGROUND

Acute kidney injury (AKI) is one of the most common complications for critically ill patients with cirrhosis, but it has remained unclear whether urine output fluctuations are associated with the risk of AKI in such patients. Thus, we explored the influence of 24-h urine-output trajectory on AKI in patients with cirrhosis through latent category trajectory modeling.

MATERIALS AND METHODS

This retrospective cohort study examined patients with cirrhosis using the MIMIC-IV database. Changes in the trajectories of urine output within 24 h after admission to the intensive care unit (ICU) were categorized using latent category trajectory modeling. The outcome examined was the occurrence of AKI during ICU hospitalization. The risk of AKI in patients with different trajectory classes was explored using the cumulative incidence function (CIF) and the Fine-Gray model with the sub-distribution hazard ratio (SHR) and the 95% confidence interval (CI) as size effects.

RESULTS

The study included 3,562 critically ill patients with cirrhosis, of which 2,467 (69.26%) developed AKI during ICU hospitalization. The 24-h urine-output trajectories were split into five classes (Classes 1-5). The CIF curves demonstrated that patients with continuously low urine output (Class 2), a rapid decline in urine output after initially high levels (Class 3), and urine output that decreased slowly and then stabilized at a lower level (Class 4) were at higher risk for AKI than those with consistently moderate urine output (Class 1). After fully adjusting for various confounders, Classes 2, 3, and 4 were associated with a higher risk of AKI compared with Class 1, and the respective SHRs (95% CIs) were 2.56 (1.87-3.51), 1.86 (1.34-2.59), and 1.83 1.29-2.59).

CONCLUSIONS

The 24-h urine-output trajectory is significantly associated with the risk of AKI in critically ill patients with cirrhosis. More attention should be paid to the dynamic nature of urine-output changes over time, which may help guide early intervention and improve patients' prognoses.

Evaluation of Renal Microhemodynamics Heterogeneity in Different Strains and Sexes of Mice

Addressing the existing gaps in our understanding of sex- and strain-dependent disparities in renal microhemodynamics, this study conducted an investigation into the variations in renal function and related biological oscillators. Using the genetically diverse mouse models BALB/c, C57BL/6, and Kunming, which serve as established proxies for the study of renal pathophysiology, we implemented laser Doppler flowmetry conjoined with wavelet transform analyses to interrogate dynamic renal microcirculation. Creatinine, urea, uric acid, glucose, and cystatin C levels were quantified to investigate potential divergences attributable to sex and genetic lineage. Our findings reveal marked sexual dimorphism in metabolite concentrations, as well as strain-specific variances, particularly in creatinine and cystatin C levels. Through the combination of Mantel tests and Pearson correlation coefficients, we delineated the associations between renal functional metrics and microhemodynamics, uncovering interactions in female BALB/c mice for creatinine and uric acid, and in male C57BL/6 mice for cystatin C. Histopathologic examination confirmed an augmented microvascular density in female mice and elucidating variations in the expression of estrogen receptor β among the strains. These data collectively highlight the influence of both sex and genetic constitution on renal microcirculation, providing an understanding that may inform the etiologic exploration of renal ailments.

Explainable Boosting Machine approach identifies risk factors for acute renal failure

BACKGROUND

Risk stratification and outcome prediction are crucial for intensive care resource planning. In addressing the large data sets of intensive care unit (ICU) patients, we employed the Explainable Boosting Machine (EBM), a novel machine learning model, to identify determinants of acute kidney injury (AKI) in these patients. AKI significantly impacts outcomes in the critically ill.

METHODS

An analysis of 3572 ICU patients was conducted. Variables such as average central venous pressure (CVP), mean arterial pressure (MAP), age, gender, and comorbidities were examined. This analysis combined traditional statistical methods with the EBM to gain a detailed understanding of AKI risk factors.

RESULTS

Our analysis revealed chronic kidney disease, heart failure, arrhythmias, liver disease, and anemia as significant comorbidities influencing AKI risk, with liver disease and anemia being particularly impactful. Surgical factors were also key; lower GI surgery heightened AKI risk, while neurosurgery was associated with a reduced risk. EBM identified four crucial variables affecting AKI prediction: anemia, liver disease, and average CVP increased AKI risk, whereas neurosurgery decreased it. Age was a progressive risk factor, with risk escalating after the age of 50 years. Hemodynamic instability, marked by a MAP below 65 mmHg, was strongly linked to AKI, showcasing a threshold effect at 60 mmHg. Intriguingly, average CVP was a significant predictor, with a critical threshold at 10.7 mmHg.

CONCLUSION

Using an Explainable Boosting Machine enhance the precision in AKI risk factors in ICU patients, providing a more nuanced understanding of known AKI risks. This approach allows for refined predictive modeling of AKI, effectively overcoming the limitations of traditional statistical models.

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.

Performances of acute kidney injury biomarkers vary according to sex

Background

Before implementing individualized strategies to treat acute kidney injury (AKI), identifying clusters of patients with divergent pathophysiological mechanisms, diagnosis criteria or outcomes is of the utmost importance. Here we studied sex-related molecular mechanisms in cardiac bypass (CBP) surgery patients developing AKI.

Methods

We compared the characteristics of 1170 patients referred for CBP surgery using multivariate logistic regression and propensity score-based analysis. Performances of the candidate urinary biomarkers at <4 h post-surgery, urinary neutrophil gelatinase-associated lipocalin (uNGAL), [IGFBP7]·[TIMP-2] product (NephroCheck) and a recently developed AKI signature of 204 urinary peptides (AKI204) to predict AKI were compared in both sexes.

Results

Incidence (∼25%) and severity of AKI were similar in men and women, even after adjustment for the usual risk factors of AKI, including baseline estimated glomerular filtration rate, age, diabetes mellitus, length of CBP and red blood cell transfusion. However, at the molecular level, performances of uNGAL, NephroCheck and AKI204 to predict AKI strongly diverged between men and women. In the full cohort, as well as in subgroups of men and women, the multimarker AKI204 signature outperformed uNGAL and NephroCheck and predicted the development of AKI significantly better in women than in men. Analysis of AKI204 at the single-peptide level suggested divergences of AKI mechanisms between sexes due to increased kidney inflammation in women (increased abundance of urinary fragments of osteopontin and uromodulin).

Conclusions

In patients referred for CBP surgery, significant clinical and biological differences between men and women as well as sexual dimorphism of AKI biomarker performances were identified. The urinary peptide signature points to sex-related molecular mechanisms underlying AKI.

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.

Sexually dimorphic renal expression of Klotho is directed by a kidney-specific distal enhancer responsive to HNF1b

Transcription enhancers are genomic sequences regulating common and tissue-specific genes and their disruption can contribute to human disease development and progression. Klotho, a sexually dimorphic gene specifically expressed in kidney, is well-linked to kidney dysfunction and its deletion from the mouse genome leads to premature aging and death. However, the sexually dimorphic regulation of Klotho is not understood. Here, we characterize two candidate Klotho enhancers using H3K27ac epigenetic marks and transcription factor binding and investigate their functions, individually and combined, through CRISPR-Cas9 genome engineering. We discovered that only the distal (E1), but not the proximal (E2) candidate region constitutes a functional enhancer, with the double deletion not causing Klotho expression to further decrease. E1 activity is dependent on HNF1b transcription factor binding site within the enhancer. Further, E1 controls the sexual dimorphism of Klotho as evidenced by qPCR and RNA-seq. Despite the sharp reduction of Klotho mRNA, unlike germline Klotho knockouts, mutant mice presented normal phenotype, including weight, lifespan, and serum biochemistry. Lastly, only males lacking E1 display more prominent acute, but not chronic kidney injury responses, indicating a remarkable range of potential adaptation to isolated Klotho loss, especially in female E1 knockouts, retaining renoprotection despite over 80% Klotho reduction.

Advances in pediatric acute kidney injury pathobiology: a report from the 26th Acute Disease Quality Initiative (ADQI) conference

BACKGROUND

In the past decade, there have been substantial advances in our understanding of the pathobiology of pediatric acute kidney injury (AKI). In particular, animal models and studies focused on the relationship between kidney development, nephron number, and kidney health have identified a number of heterogeneous pathophysiologies underlying AKI. Despite this progress, gaps remain in our understanding of the pathobiology of pediatric AKI.

METHODS

During the 26th Acute Disease Quality Initiative (ADQI) Consensus conference, a multidisciplinary group of experts discussed the evidence and used a modified Delphi process to achieve consensus on recommendations for opportunities to advance translational research in pediatric AKI. The current state of research understanding as well as gaps and opportunities for advancement in research was discussed, and recommendations were summarized.

RESULTS

Consensus was reached that to improve translational pediatric AKI advancements, diverse teams spanning pre-clinical to epidemiological scientists must work in concert together and that results must be shared with the community we serve with patient involvement. Public and private research support and meaningful partnerships with adult research efforts are required. Particular focus is warranted to investigate the pediatric nuances of AKI, including the effect of development as a biological variable on AKI incidence, severity, and outcomes.

CONCLUSIONS

Although AKI is common and associated with significant morbidity, the biologic basis of the disease spectrum throughout varying nephron developmental stages remains poorly understood. An incomplete understanding of factors contributing to kidney health, the diverse pathobiologies underlying AKI in children, and the historically siloed approach to research limit advances in the field. The recommendations outlined herein identify gaps and outline a strategic approach to advance the field of pediatric AKI via multidisciplinary translational research.

Differences in the epidemiology, management and outcomes of kidney disease in men and women

Improved understanding of differences in kidney disease epidemiology, management and outcomes in men and women could help nephrologists to better meet the needs of their patients from a sex- and gender-specific perspective. Evidence of sex differences in the risk and outcomes of acute kidney injury is mixed and dependent on aetiology. Women have a higher prevalence of chronic kidney disease (CKD) stages 3-5 than men, whereas men have a higher prevalence of albuminuria and hence CKD stages 1-2. Men show a faster decline in kidney function, progress more frequently to kidney failure and have higher mortality and risk of cardiovascular disease than women. However, the protective effect of female sex is reduced with CKD progression. Women are less likely than men to be aware of, screened for and diagnosed with CKD, started on antiproteinuric medication and referred to nephrologist care. They also consistently report a poorer health-related quality of life and a higher symptom burden than men. Women experience greater barriers than men to access the waiting list for kidney transplantation, particularly with respect to older age and obesity. However, women also have longer survival than men after transplantation, which may partly explain the comparable prevalence of transplantation between the sexes.

Sex and Gender Differences in AKI

Sex differences in AKI continue to be identified. Generally, women are protected from AKI when compared to men. Much of the protection exhibited in women is diminished after menopause. These sex and age effects have also been noted in animal models of AKI. Gonadal hormones, as modifiers of incidence, severity, and progression of AKI, have been offered as likely contributors to this sex and age effect. In animal models of AKI, estrogen and testosterone seem to modulate susceptibility. Questions remain however regarding cellular and molecular changes that are initiated by modulation of these hormones because both estrogen and testosterone have effects across cell types that play a role in AKI. Although findings have largely been informed by studies in males, molecular pathways that are involved in the initiation and progression of AKI may be modulated by gonadal hormones. Compounding the hormone-receptor effects are developmental effects of sex chromosomal complement and epigenetic influences that may confer sex-based baseline differences in gene and protein expression, and gene dosage effects of X inactivation and escape on molecular pathways. Elucidation of sex-based protection may afford a more complete view of AKI and potential therapeutic interventions. Furthermore, the effect on susceptibility to AKI in transgender patients, who receive life-altering and essential gender-affirming hormone therapy, requires greater attention. In this review, several potential contributors to the sex differences observed in humans and animal models are discussed.

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.

Gender differences and risk factors for acute kidney injury following cardiac surgery: A single center retrospective cohort study

Background

We studied AKI incidence and prognosis in cardiac surgery patients under and over 60 years old.

Methods

We studied AKI in patients who underwent cardiac surgery at the First Affiliated Hospital of Wenzhou Medical University between Jan 2020 and Dec 2021, using improved global prognostic criteria for diagnosis.

Results

After analyzing 781 patients (402 males, 379 females), AKI incidence after surgery was 30.22 %. Adjusting for propensity scores revealed no significant difference in AKI incidence between young males (24.1 %) and females (19.3 %). However, young females had higher AKI stages. Among older patients, AKI incidence was comparable between males (43.4 %) and females (42.2 %), but females had longer intubation times. Independent risk factors for AKI included age, male gender, and BMI, while intraoperative hemoglobin level was protective.

Conclusions

No gender gap in AKI frequency for <60 years old and ≥60 years old post-cardiac surgery, yet women display increased AKI severity and extended intubation duration.

Acute kidney injury associated with nephrotoxic drugs in critically ill patients: a multicenter cohort study using electronic health record data

Background

Nephrotoxic drugs frequently cause acute kidney injury (AKI) in adult intensive care unit (ICU) patients. However, there is a lack of large pharmaco-epidemiological studies investigating the associations between drugs and AKI. Importantly, AKI risk factors may also be indications or contraindications for drugs and thereby confound the associations. Here, we aimed to estimate the associations between commonly administered (potentially) nephrotoxic drug groups and AKI in adult ICU patients whilst adjusting for confounding.

Methods

In this multicenter retrospective observational study, we included adult ICU admissions to 13 Dutch ICUs. We measured exposure to 44 predefined (potentially) nephrotoxic drug groups. The outcome was AKI during ICU admission. The association between each drug group and AKI was estimated using etiological cause-specific Cox proportional hazard models and adjusted for confounding. To facilitate an (independent) informed assessment of residual confounding, we manually identified drug group-specific confounders using a large drug knowledge database and existing literature.

Results

We included 92 616 ICU admissions, of which 13 492 developed AKI (15%). We found 14 drug groups to be associated with a higher hazard of AKI after adjustment for confounding. These groups included established (e.g. aminoglycosides), less well established (e.g. opioids) and controversial (e.g. sympathomimetics with α- and β-effect) drugs.

Conclusions

The results confirm existing insights and provide new ones regarding drug associated AKI in adult ICU patients. These insights warrant caution and extra monitoring when prescribing nephrotoxic drugs in the ICU and indicate which drug groups require further investigation.

Direct androgen receptor control of sexually dimorphic gene expression in the mammalian kidney

Mammalian organs exhibit distinct physiology, disease susceptibility, and injury responses between the sexes. In the mouse kidney, sexually dimorphic gene activity maps predominantly to proximal tubule (PT) segments. Bulk RNA sequencing (RNA-seq) data demonstrated that sex differences were established from 4 and 8 weeks after birth under gonadal control. Hormone injection studies and genetic removal of androgen and estrogen receptors demonstrated androgen receptor (AR)-mediated regulation of gene activity in PT cells as the regulatory mechanism. Interestingly, caloric restriction feminizes the male kidney. Single-nuclear multiomic analysis identified putative cis-regulatory regions and cooperating factors mediating PT responses to AR activity in the mouse kidney. In the human kidney, a limited set of genes showed conserved sex-linked regulation, whereas analysis of the mouse liver underscored organ-specific differences in the regulation of sexually dimorphic gene expression. These findings raise interesting questions on the evolution, physiological significance, disease, and metabolic linkage of sexually dimorphic gene activity.

Sex and gender differences in intensive care medicine

Despite significant advancements in critical care medicine, limited attention has been given to sex and gender disparities in management and outcomes of patients admitted to the intensive care unit (ICU). While "sex" pertains to biological and physiological characteristics, such as reproductive organs, chromosomes and sex hormones, "gender" refers more to sociocultural roles and human behavior. Unfortunately, data on gender-related topics in the ICU are lacking. Consequently, data on sex and gender-related differences in admission to the ICU, clinical course, length of stay, mortality, and post-ICU burdens, are often inconsistent. Moreover, when examining specific diagnoses in the ICU, variations can be observed in epidemiology, pathophysiology, presentation, severity, and treatment response due to the distinct impact of sex hormones on the immune and cardiovascular systems. In this narrative review, we highlight the influence of sex and gender on the clinical course, management, and outcomes of the most encountered intensive care conditions, in addition to the potential co-existence of unconscious biases which may also impact critical illness. Diagnoses with a known sex predilection will be discussed within the context of underlying sex differences in physiology, anatomy, and pharmacology with the goal of identifying areas where clinical improvement is needed. To optimize patient care and outcomes, it is crucial to comprehend and address sex and gender differences in the ICU setting and personalize management accordingly to ensure equitable, patient-centered care. Future research should focus on elucidating the underlying mechanisms driving sex and gender disparities, as well as exploring targeted interventions to mitigate these disparities and improve outcomes for all critically ill patients.

Erythrocyte parameters, anemia conditions, and sex differences are associated with the incidence of contrast-associated acute kidney injury after coronary angiography

Objective

Contrast-associated acute kidney injury (CA-AKI) is a critical complication when applying contrast medium, and the risk factors of CA-AKI have not been fully clarified. This study aimed to explore the relationships of CA-AKI with erythrocyte parameters, anemia conditions, and sex differences in patients after coronary angiography (CAG).

Methods

In this retrospective study, 4,269 patients who underwent CAG were enrolled. CA-AKI was defined as an increase in plasma creatinine of at least 0.5 mg/dl (44 μmol/L) or 25% within 72 h after exposure to the contrast medium. Three erythrocyte parameters, including hemoglobin, hematocrit, and red blood cell (RBC) count, were collected on admission. Logistic regression analyses were used to examine the associations of sex differences and erythrocyte parameters with CA-AKI in the overall population, restricted cubic splines to visualize these associations flexibly. Moreover, stratified and sensitivity analyses were conducted to assess the robustness of the findings.

Results

Overall, the mean (± standard deviations) age of patients was 67.05 ± 10.77 years, and 759 subjects (17.8%) developed CA-AKI. The results showed L-shaped relationships between erythrocyte parameters and CA-AKI incidence in each model (all P < 0.001). The incidence of CA-AKI was positively associated with the severity of anemia, while it showed no significant differences among the types of anemia. Moreover, female patients undergoing CAG had a higher risk of CA-AKI than male patients. Mediation analysis verified that erythrocyte parameters exerted an indirect effect on the sex differences of CA-AKI incidences.

Conclusion

In conclusion, females, perioperative anemia conditions, and lower erythrocyte parameters (hemoglobin, hematocrit, and RBC count) were verified as risk factors of CA-AKI in patients undergoing CAG. Furthermore, lower erythrocyte parameters among females exerted indirect effects on the sex differences in CA-AKI incidence.

Direct androgen receptor regulation of sexually dimorphic gene expression in the mammalian kidney

Mammalian organs exhibit distinct physiology, disease susceptibility and injury responses between the sexes. In the mouse kidney, sexually dimorphic gene activity maps predominantly to proximal tubule (PT) segments. Bulk RNA-seq data demonstrated sex differences were established from 4 and 8 weeks after birth under gonadal control. Hormone injection studies and genetic removal of androgen and estrogen receptors demonstrated androgen receptor (AR) mediated regulation of gene activity in PT cells as the regulatory mechanism. Interestingly, caloric restriction feminizes the male kidney. Single-nuclear multiomic analysis identified putative cis-regulatory regions and cooperating factors mediating PT responses to AR activity in the mouse kidney. In the human kidney, a limited set of genes showed conserved sex-linked regulation while analysis of the mouse liver underscored organ-specific differences in the regulation of sexually dimorphic gene expression. These findings raise interesting questions on the evolution, physiological significance, and disease and metabolic linkage, of sexually dimorphic gene activity.

Immune checkpoint inhibitor-associated acute kidney injury in patients with cancer: a systematic review and meta-analysis of risk factors

BACKGROUND

As a novel antineoplastic drug, immune checkpoint inhibitors (ICIs) are associated with a spectrum of autoimmune-related side effects, including acute kidney injury (AKI). Understanding the risk factors for immune-associated acute kidney injury will inform future symptom management measures to reduce this risk. This study aims to identify the risk factors for ICIs-AKI in cancer patients through a systematic review and meta-analysis.

METHODS

The systematic search was conducted in The Cochrane Library, Pubmed, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), Wanfang Data, and VIP Database. The related studies published since the establishment of the database to Aug 22, 2022, were screened, data was extracted following the inclusion and exclusion criteria, and the quality of the selected studies was assessed by Newcastle-Ottawa Scale (NOS). The above was performed independently by the two reviewers. The estimated pooled odds ratios (ORs) for risk factors of developing ICIs-AKI were conducted by random-effects meta-analysis.

RESULTS

A total of 8 publications, including 5267 patients, were included. Meta-analysis results showed that extrarenal immune-related adverse events (irAEs), therapy with the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), male, hypertension, pre-existent use of a diuretic, and a proton pump inhibitor (PPI) were significantly correlated to ICIs-AKI.

CONCLUSIONS

We identified extrarenal irAEs, CTLA-4 treatments, males, hypertension, previous use of diuretics, and PPIs are essential predictors of ICIs-AKI. These findings are helpful for healthcare providers to monitor ICIs-AKI for management and timely interventions.

Acute kidney injury development and impact on clinical and economic outcomes in patients with cirrhosis: an observational cohort study over a 10-year period

OBJECTIVES

Acute kidney injury (AKI) is a severe complication that is associated with significant morbidity and mortality in hospitalized cirrhotic patients. Data about AKI incidence and outcomes in patients with cirrhosis is scarce in the Middle East region. This study explored the incidence and impact of AKI on clinical and economic outcomes in cirrhosis.

METHODS

This was a retrospective cohort study of cirrhosis patients admitted to an educational hospital in Jordan during the years 2012-2022. Demographics, clinical and biochemical information, and charges were retrieved from medical electronic records. Logistic regression models were conducted to evaluate predictors of AKI and mortality in cirrhosis adjusting for covariates. Hospital charges were also described.

RESULTS

A total of 380 cirrhosis patients were included with an AKI incidence of 27.9%. Male sex, elevated baseline serum creatinine, presence of spontaneous bacterial peritonitis, and higher comorbidity score were independently associated with AKI development ( P < 0.05). The hospital mortality rate was markedly higher for patients with AKI versus those without AKI (51.9% vs. 6.2%, respectively; P < 0.001). AKI was associated independently with higher odds of hospital death (OR = 5.83, P < 0.001), prolongation of the median hospital stays by 5 days ( P < 0.001), more clinical complications, and increased total hospital charges per admission by $2500.

CONCLUSION

AKI is prevalent in cirrhosis patients, and it is associated with increased mortality, hospitalization, and cost. This burden in cirrhosis emphasizes the need for early identification of patients at high risk of AKI and applying prompt and effective management approaches, aiming at improving outcomes.

Incidence, predictors and prognosis of acute kidney injury in acute ST-segment elevation myocardial infarction patients undergoing emergent coronary angiography/primary percutaneous coronary intervention

BACKGROUND

Acute kidney injury (AKI) after coronary angiography (CAG) and primary percutaneous coronary intervention (PPCI) is frequently observed, and often interpreted as contrast induced-AKI. This study aimed to investigate the incidence, predictors and outcomes of AKI in acute ST-segment elevation myocardial infarction (STEMI) patients undergoing emergent CAG/PPCI using the control group of STEMI patients who were not exposed to contrast agents within the first 72 h.

METHODS

We performed a retrospective analysis of 1670 STEMI patients. Of them, 673 patients underwent emergent CAG/PPCI, and 997 patients treated with thrombolysis or no reperfusion therapy who were not exposed to contrast material during the first 72 h. AKI was defined as an increase of serum creatinine ≥ 44.2 mmol/L or ≥ 25% from baseline within 72 h. Patents were then followed up for the occurrence of all-cause mortality for 40 months (interquartile range: 24-55 months).

RESULTS

After propensity score matching, 505 pairs of patients were matched. Overall, the incidence of AKI was 27.4%, and AKI rates were not significantly different in patients with and without emergent CAG/PPCI procedure (27.5% vs. 27.3%, P = 0.944). Multivariate logistic regression analysis identified that the independent predictors of AKI were female, elevated interleukin-6 level, decreased lymphocyte count, left ventricular ejection fraction < 50% and use of diuretics in patients with emergent CAG/PPCI. Patients with AKI than those without AKI experienced higher incidence of acute heart failure with Killip class III (9.4% vs. 3.3%, P = 0.005; 15.2% vs. 6.8%, P = 0.003, respectively) and mortality (5.8% vs. 1.4%, P = 0.014; 12.3% vs. 4.6%, P = 0.002, respectively) in patients with and without emergent CAG/PPCI. Multivariate Cox regression analysis confirmed that AKI was independently associated with long-term mortality rate at 40 months follow-up in patients with and without emergent CAG/PPCI (HR = 1.867, 95% CI: 1.086-3.210, P = 0.024; HR = 1.700, 95% CI: 1.219-2.370, P = 0.002, respectively).

CONCLUSIONS

Approximately 27.0% of STEMI patients experience AKI, which is strongly associated with an increased short- and long-term mortality regardless of emergent CAG/PPCI procedure. The development of AKI is mainly related to female gender, inflammation reaction, heart failure and use of diuretics in STEMI patients undergoing emergent CAG/PPCI.

The Presence of Testis Determines Aristolochic Acid-Induced Nephrotoxicity in Mice

Aristolochic acid (AA) is notorious for inducing nephrotoxicity, but the influence of sex on AA-induced kidney injury was not clear. This study sought to investigate sex differences in kidney dysfunction and tubular injury induced by AA. Male and female mice were bilaterally orchiectomized and ovariectomized, respectively. Fourteen days after gonadectomy, the mice were intraperitoneally injected with AA (10 mg/kg body weight/day) daily for 2 days and sacrificed 7 days after the first injection. Body weight, kidney function, and tubular structure were assessed. When compared between male and female non-gonadectomized mice, AA-induced body weight loss was greater in male mice than in female mice. Functional and structural damages in male kidneys were markedly induced by AA injection, but kidneys in AA-injected female mice showed no or mild damages. Ovariectomy had no effect on AA-induced nephrotoxic acute kidney injury in female mice. However, orchiectomy significantly reduced body weight loss, kidney dysfunction, and tubular injury in AA-induced nephrotoxicity in male mice. This study has demonstrated that testis causes AA-induced nephrotoxic acute kidney injury.

Postoperative Acute Kidney Injury by Age and Sex: A Retrospective Cohort Association Study

BACKGROUND

Acute kidney injury (AKI) after noncardiac surgery is common and has substantial health impact. Preclinical and clinical studies examining the influence of sex on AKI have yielded conflicting results, although they typically do not account for age-related changes. The objective of the study was to determine the association of age and sex groups on postoperative AKI. The authors hypothesized that younger females would display lower risk of postoperative AKI than males of similar age, and the protection would be lost in older females.

METHODS

This was a multicenter retrospective cohort study across 46 institutions between 2013 and 2019. Participants included adult inpatients without pre-existing end-stage kidney disease undergoing index major noncardiac, nonkidney/urologic surgeries. The authors' primary exposure was age and sex groups defined as females 50 yr or younger, females older than 50 yr, males 50 yr or younger, and males older than 50 yr. The authors' primary outcome was development of AKI by Kidney Disease-Improving Global Outcomes serum creatinine criteria. Exploratory analyses included associations of ascending age groups and hormone replacement therapy home medications with postoperative AKI.

RESULTS

Among 390,382 patients, 25,809 (6.6%) developed postoperative AKI (females 50 yr or younger: 2,190 of 58,585 [3.7%]; females older than 50 yr: 9,320 of 14,4047 [6.5%]; males 50 yr or younger: 3,289 of 55,503 [5.9%]; males older than 50 yr: 11,010 of 132,447 [8.3%]). When adjusted for AKI risk factors, compared to females younger than 50 yr (odds ratio, 1), the odds of AKI were higher in females older than 50 yr (odds ratio, 1.51; 95% CI, 1.43 to 1.59), males younger than 50 yr (odds ratio, 1.90; 95% CI, 1.79 to 2.01), and males older than 50 yr (odds ratio, 2.06; 95% CI, 1.96 to 2.17).

CONCLUSIONS

Younger females display a lower odds of postoperative AKI that gradually increases with age. These results suggest that age-related changes in women should be further studied as modifiers of postoperative AKI risk after noncardiac surgery.

EDITOR’S PERSPECTIVE

Association of prognostic nutritional index with risk of contrast induced nephropathy: A meta-analysis

Background

Although prognostic nutritional index (PNI) has been frequently applied in patients with malignancy or those during postoperative recovery, whether it is also an optimal indicator of the risk of contrast-induced nephropathy (CIN) in patients receiving coronary angiography remains uncertain. This meta-analysis aimed at investigating the clinical association of PNI with the risk of CIN in patients receiving coronary angiography or percutaneous coronary intervention.

Methods

Embase, Medline, Cochrane Library, and Google scholar were searched for studies until January 2023. The relationship between CIN risk and PNI (i.e., low vs. high) (primary outcome) as well as other variables (secondary outcomes) were analyzed using a random-effects model.

Results

Overall, 10 observational studies with 17,590 patients (pooled incidence of CIN: 18%) were eligible for analysis. There was a higher risk of CIN in patients with a low PNI compared to those with a high PNI [odd ratio (OR) = 3.362, 95% confidence interval (CI): 2.054 to 5.505, p < 0.0001, I ² = 89.6%, seven studies, 12,972 patients, certainty of evidence: very low]. Consistently, a lower PNI was noted in patients with CIN compared to those without (Mean difference = -5.1, 95% CI: -6.87 to -3.33, p < 0.00001, I ² = 96%, eight studies, 15,516 patients, certainty of evidence: very low). Other risks of CIN included diabetes and hypertension, while male gender and the use of statins were associated with a lower risk of CIN. Patients with CIN were older, had a higher creatinine level, and received a higher contrast volume compared to those without. On the other hand, pre-procedural albumin, estimated glomerular filtration rate, ejection fraction, hemoglobin, lymphocyte ratio were found to be lower in patients with CIN than in those without.

Conclusion

This meta-analysis highlighted an inverse association of PNI with the risk of CIN, which required further studies for verification.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/], identifier [CRD42023389185].

Single-cell profiling of healthy human kidney reveals features of sex-based transcriptional programs and tissue-specific immunity

Knowledge of the transcriptional programs underpinning the functions of human kidney cell populations at homeostasis is limited. We present a single-cell perspective of healthy human kidney from 19 living donors, with equal contribution from males and females, profiling the transcriptome of 27677 cells to map human kidney at high resolution. Sex-based differences in gene expression within proximal tubular cells were observed, specifically, increased anti-oxidant metallothionein genes in females and aerobic metabolism-related genes in males. Functional differences in metabolism were confirmed in proximal tubular cells, with male cells exhibiting higher oxidative phosphorylation and higher levels of energy precursor metabolites. We identified kidney-specific lymphocyte populations with unique transcriptional profiles indicative of kidney-adapted functions. Significant heterogeneity in myeloid cells was observed, with a MRC1+LYVE1+FOLR2+C1QC+ population representing a predominant population in healthy kidney. This study provides a detailed cellular map of healthy human kidney, and explores the complexity of parenchymal and kidney-resident immune cells.

Gender and Renal Insufficiency: Opportunities for Their Therapeutic Management?

Acute kidney injury (AKI) is a major clinical problem associated with increased morbidity and mortality. Despite intensive research, the clinical outcome remains poor, and apart from supportive therapy, no other specific therapy exists. Furthermore, acute kidney injury increases the risk of developing chronic kidney disease (CKD) and end-stage renal disease. Acute tubular injury accounts for the most common intrinsic cause of AKI. The main site of injury is the proximal tubule due to its high workload and energy demand. Upon injury, an intratubular subpopulation of proximal epithelial cells proliferates and restores the tubular integrity. Nevertheless, despite its strong regenerative capacity, the kidney does not always achieve its former integrity and function and incomplete recovery leads to persistent and progressive CKD. Clinical and experimental data demonstrate sexual differences in renal anatomy, physiology, and susceptibility to renal diseases including but not limited to ischemia-reperfusion injury. Some data suggest the protective role of female sex hormones, whereas others highlight the detrimental effect of male hormones in renal ischemia-reperfusion injury. Although the important role of sex hormones is evident, the exact underlying mechanisms remain to be elucidated. This review focuses on collecting the current knowledge about sexual dimorphism in renal injury and opportunities for therapeutic manipulation, with a focus on resident renal progenitor stem cells as potential novel therapeutic strategies.

Relationship between intraoperative tidal volume and acute kidney injury following off-pump coronary artery bypass grafting: A retrospective observational study

The effect of intraoperative tidal volume (VT) on clinical outcomes after off-pump coronary artery bypass grafting (OPCAB) has not been studied. The aim of this study was to assess the relationship between intraoperative tidal volume (VT) and acute kidney injury (AKI ) after OPCAB. A total of 1049 patients who underwent OPCAB between January 2009 and December 2018 were analyzed. Patients were divided into high (>8 ml/kg) and low VT (≤8 ml/kg) groups (intraoperative median VT standardized to predicted body weight). The data were fitted using a multivariable logistic regression model. Subgroup analyses were performed according to age, sex, comorbidities, preoperative laboratory variables, operative profiles, and Cleveland score. The risk of AKI was not significantly higher in the high than the low VT group (OR: 1.15, 95% CI: 0.80-1.66; P = .459); however, subgroup analyses revealed that a high VT may increase the risk of AKI in males, patients aged < 70 years, with chronic kidney disease, a left ventricular ejection fraction < 35%, or a long duration of surgery. High intraoperative VTs were not associated with an increased risk of AKI after OPCAB. Nonetheless, it may increase the risk of AKI in certain subgroups, such as younger age, male sex, reduced renal and cardiac function, and a long surgery time.

Sex differences in resilience to ferroptosis underlie sexual dimorphism in kidney injury and repair

In both humans and mice, repair of acute kidney injury is worse in males than in females. Here, we provide evidence that this sexual dimorphism results from sex differences in ferroptosis, an iron-dependent, lipid-peroxidation-driven regulated cell death. Using genetic and single-cell transcriptomic approaches in mice, we report that female sex confers striking protection against ferroptosis, which was experimentally induced in proximal tubular (PT) cells by deleting glutathione peroxidase 4 (Gpx4). Single-cell transcriptomic analyses further identify the NFE2-related factor 2 (NRF2) antioxidant protective pathway as a female resilience mechanism against ferroptosis. Genetic inhibition and pharmacological activation studies show that NRF2 controls PT cell fate and plasticity by regulating ferroptosis. Importantly, pharmacological NRF2 activation protects male PT cells from ferroptosis and improves cellular plasticity as in females. Our data highlight NRF2 as a potential therapeutic target to prevent failed renal repair after acute kidney injury in both sexes by modulating cellular plasticity.

Relation of Gender to the Occurrence of AKI in STEMI Patients

Patients undergoing percutaneous coronary interventions (PCIs) are prone to a wide range of complications; one complication that is constantly correlated with a worse prognosis is acute kidney injury (AKI). Gender as an independent risk factor for said complications has raised some interest; however, studies have shown conflicting results so far. We aimed to investigate the possible relation of gender to the occurrence of AKI in STEMI patients undergoing PCI. This retrospective observational study cohort included 2967 consecutive patients admitted with STEMI between the years 2008 and 2019. Their renal outcomes were assessed according to KDIGO criteria (AKI serum creatinine ≥ 0.3 mg/dL from baseline within 48 h from admission), and in-hospital complications and mortality were reviewed. Our main results show that female patients were older (69 vs. 60, p < 0.001) and had higher rates of diabetes (29.2% vs. 23%, p < 0.001), hypertension (62.9% vs. 41.3%, p < 0.001), and chronic kidney disease (26.7% vs. 19.3%, p < 0.001). Females also had a higher rate of AKI (12.7% vs. 7.8%, p < 0.001), and among patients with AKI, severe AKI was also more prevalent in females (26.1% vs. 14.5%, p = 0.03). However, in multivariate analyses, after adjusting for the baseline characteristics above, the female gender was a non-significant predictor for AKI (adjusted OR 1.01, 95% CI 0.73−1.4, p = 0.94) or severe AKI (adjusted OR 1.65, 95% CI 0.80−1.65, p = 0.18). In conclusion, while females had higher rates of AKI and severe AKI, gender was not independently associated with AKI after adjusting for other confounding variables. Other comorbidities that are more prevalent in females can account for the difference in AKI between genders.

Integrated single-cell transcriptomics and proteomics reveal cellular-specific response and microenvironment remodeling in aristolochic acid nephropathy

Aristolochic acid nephropathy (AAN) is characterized by acute proximal tubule necrosis and immune cell infiltration, contributing to the global burden of chronic kidney disease and urothelial cancer. Although the proximal tubule has been defined as the primary target of aristolochic acids I (AAI), the mechanistic underpinning of gross renal deterioration caused by AAI has not been explicitly explained, prohibiting effective therapeutic intervention. To this point, we employed integrated single-cell RNA-Seq, bulk RNA-Seq, and mass spectrometry–based proteomics to analyze the mouse kidney after acute AAI exposure. Our results reveal a dramatic reduction of proximal tubule epithelial cells, associated with apoptotic and inflammatory pathways, indicating permanent damage beyond repair. We found the enriched development pathways in other nephron segments, suggesting activation of reparative programs triggered by AAI. The divergent response may be attributed to the segment-specific distribution of organic anion channels along the nephron, including OAT1 and OAT3. Moreover, we observed dramatic activation and recruitment of cytotoxic T and macrophage M1 cells, highlighting inflammation as a principal contributor to permanent renal injury. Ligand-receptor pairing revealed that critical intercellular crosstalk underpins damage-induced activation of immune cells. These results provide potentially novel insight into the AAI-induced kidney injury and point out possible pathways for future therapeutic intervention.

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.

Sex as a Biological Factor in the Changes in Disease Patients During Ramadan Intermittent Fasting: A Systematic Review

Background

During Ramadan, many patients with diabetes, renal, cardiovascular, gastrointestinal diseases, headaches, and epilepsy choose to fast even against their doctor's advice. The impact of this intermittent fasting on health and disease could be different in men and women. The aim of this study was to determine the effect of sex as a factor in diseases outcomes of patients who opt to fast during Ramadan.

Main Body

The articles included in this study reported data on six diseases: diabetes, renal, cardiovascular, gastrointestinal diseases, headaches, and epilepsy. A systematic search was performed on PubMed and Scopus for observational and clinical studies mentioning Ramadan, diabetes, renal, cardiovascular, gastrointestinal diseases, headaches, and epilepsy in both men and women. Data was extracted by two independent reviewers using a standardized data-collection form. From 381 original articles, 38 studies were selected, including 25,023 patients of which 44.4% were women. Sex-based differences were reported by 18 studies for several variables such as body mass index, blood glucose, the frequency of hypoglycemia, renal colic, mortality, thrombosis, and gastrointestinal diseases in patients fasting during Ramadan. Most of the differences between men and women were reported both in the baseline period before Ramadan and during Ramadan. Indeed, during the period outside Ramadan, the frequency of renal colic, cardiovascular, gastrointestinal diseases, were higher in men; while body mass index, Thrombosis, and headache were higher in women. In the remaining 21 studies, it was reported that the sex factor was not associated with the effect of Ramadan fasting in the frequency and other outcomes of these diseases.

Conclusion

Currently, small attention is paid to sex as a determinant factor in patients while fasting during Ramadan. There appeared to be differences in the frequency and incidence of diseases in men and women during Ramadan. Closer attention to sex differences regarding the frequency and the progression of the diseases during fasting may help to improve patient care, especially to benefit those patients willing to fast during Ramadan.

Baseline Serum Estradiol Level Is Associated with Acute Kidney Injury in Patients with Moderately Severe and Severe Acute Pancreatitis

Background. Sexual dimorphism with critical diseases has been documented. However, the role of serum sex hormones for the presence of acute kidney injury (AKI) in moderately or severe acute pancreatitis (MSAP and SAP) patients remains controversial. Here we set out to evaluate whether early (first 48 h) serum estradiol level is associated with AKI in patients with MSAP and SAP. Patients and Methods. We retrospectively collected data from patients with preliminary diagnosis of MSAP and SAP from the Affiliated Hospital of Yangzhou University between January 2014 and June 2018. Serum sex hormones were extracted for further assessment within first 48 h following admission. Logistic regression analysis and the receiving operating characteristic (ROC) curve were applied to evaluate the association and correlation between serum sex hormones and AKI. Results. Data from a total of 122 patients with MSAP or SAP were enrolled in this study. There were no differences in the incidence of AKI between males and females. However, comparing with patients without AKI, those with AKI saw higher estradiol level ( $p\le 0.01$ ) and slight higher progesterone level ( $p=0.014$ ) but similar testosterone level ( $p=0.668$ ). Interestingly, during both the manual selection and the stepwise backward logistic regression analysis, serum estradiol level was independently associated with AKI in patients with MSAP and SAP (OR 4.699, CI 1.783-12.386, and $p=0.002$ ). Additionally, area under the curve of ROC (AUCROC) showed that serum estradiol level was a proper predictor for AKI (area under the curve 0.875). Specifically, the serum estradiol level of 223.15 pg/mL demonstrated a 92.3% sensitive and a 79.3% specificity in predicting AKI of MSAP and SAP patients, respectively. Conclusions. High baseline serum estradiol level appears to be an independent risk factor for AKI in patients with MSAP and SAP. It also tends to be an appropriate indicator for AKI.

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.

Gender Differences in Age-Stratified Inhospital Outcomes After Transcatheter Aortic Valve Implantation (from the National Inpatient Sample 2012 to 2018)

Contemporary data on gender differences in outcomes after transcatheter aortic valve implantation (TAVI), after stratification by age, remain limited. We studied age-stratified (60 to 70, 71 to 80, and 81 to 90 years) inhospital outcomes by gender after TAVI from the National Inpatient Sample database between 2012 and 2018. We analyzed National Inpatient Sample data using the International Classification of Diseases, Clinical Modification, Ninth Revision, and Tenth Revision claims codes. Between the years 2012 and 2018, a total of 188,325 weighted hospitalizations for TAVI were included in the analysis. A total of 21,957 patients were included in the 60 to 70 age group (44% females), 60,770 (45% females) in the 71 to 80 age group, and 105,580 (50% females) in the 81 to 90 age groups, respectively. Propensity-matched inhospital mortality rates were significantly higher for females than males for the age group of 81 to 90 years (3.0% vs 2.1%, p <0.01). Vascular complications and a need for blood transfusions remained significantly higher for females on propensity-matched analysis across all categories of ages. Conversely, acute kidney injury and the need for pacemaker implantation remained significantly higher for males across all age groups. In conclusion, we report that mortality is higher in female patients who underwent TAVI between the ages of 81 to 90. Moreover, the female gender was associated with higher vascular complications and bleeding requiring transfusions. Conversely, the male gender was associated with higher rates of pacemaker implantation and acute kidney injury.

The molecular chaperone GRP170 protects against ER stress and acute kidney injury in mice

Molecular chaperones are responsible for maintaining cellular homeostasis, and one such chaperone, GRP170, is an endoplasmic reticulum (ER) resident that oversees both protein biogenesis and quality control. We previously discovered that GRP170 regulates the degradation and assembly of the epithelial sodium channel (ENaC), which reabsorbs sodium in the distal nephron and thereby regulates salt-water homeostasis and blood pressure. To define the role of GRP170 - and, more generally, molecular chaperones in kidney physiology - we developed an inducible, nephron-specific GRP170-KO mouse. Here, we show that GRP170 deficiency causes a dramatic phenotype: profound hypovolemia, hyperaldosteronemia, and dysregulation of ion homeostasis, all of which are associated with the loss of ENaC. Additionally, the GRP170-KO mouse exhibits hallmarks of acute kidney injury (AKI). We further demonstrate that the unfolded protein response (UPR) is activated in the GRP170-deficient mouse. Notably, the UPR is also activated in AKI when originating from various other etiologies, including ischemia, sepsis, glomerulonephritis, nephrotic syndrome, and transplant rejection. Our work establishes the central role of GRP170 in kidney homeostasis and directly links molecular chaperone function to 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.

Experimental models of acute kidney injury for translational research

Preclinical models of human disease provide powerful tools for therapeutic discovery but have limitations. This problem is especially apparent in the field of acute kidney injury (AKI), in which clinical trial failures have been attributed to inaccurate modelling performed largely in rodents. Multidisciplinary efforts such as the Kidney Precision Medicine Project are now starting to identify molecular subtypes of human AKI. In addition, over the past decade, there have been developments in human pluripotent stem cell-derived kidney organoids as well as zebrafish, rodent and large animal models of AKI. These organoid and AKI models are being deployed at different stages of preclinical therapeutic development. However, the traditionally siloed, preclinical investigator-driven approaches that have been used to evaluate AKI therapeutics to date rarely account for the limitations of the model systems used and have given rise to false expectations of clinical efficacy in patients with different AKI pathophysiologies. To address this problem, there is a need to develop more flexible and integrated approaches, involving teams of investigators with expertise in a range of different model systems, working closely with clinical investigators, to develop robust preclinical evidence to support more focused interventions in patients with AKI.

Short- and long-term outcomes of intensive care patients with acute kidney disease

BACKGROUND

Acute kidney disease (AKD) is a proposed definition for acute kidney injury (AKI) lasting 7 days or longer. Little has been reported regarding characteristics of patients with AKD and their short- and long-term outcomes. We describe the epidemiology and risk factors for AKD and outcomes following AKD.

METHODS

This retrospective observational cohort study identified patients aged 16 or older admitted to the Glasgow Royal Infirmary and Queen Elizabeth University Hospital intensive care units (ICUs) in Scotland between 1st July 2015 and 30th June 2018. Baseline serum creatinine and subsequent values were used to identify patients with de-novo kidney injury (DNKI). Patients with recovery prior to day 7 were classified as AKI; recovery at day 7 or beyond was classified as AKD. Outcomes were in-hospital and long-term mortality, and proportion of major adverse kidney events (MAKEs). Multivariable logistic regression was used to identify risk factors for AKD. A Cox proportional hazards model was used to identify factors associated with long-term outcomes.

FINDINGS

Of the 5,334 patients admitted to ICU who were assessed for DNKI, 1,620 (30·4%) suffered DNKI and of these, 403 (24·9%) met AKD criteria; 984 (60·7%) were male and the median age was 60·0 (IQR=48·0-72·0). Male sex, sepsis and lower baseline estimated glomerular filtration rate (eGFR) were associated with development of AKD. In-ICU (16·1%vs6·2%) and in-hospital (26·1%vs11·6%) mortality rates were significantly higher in AKD patients than AKI patients. Long-term survival was not different for AKD patients (HR=1·16; p-value=0·261) but AKD was associated with subsequent MAKEs (OR=1·25).

INTERPRETATION

One in four ICU patients with DNKI met AKD criteria. These patients had an increased risk of short-term mortality and long-term MAKEs. Whilst the trend for long-term survival was lower, this was not significantly different from shorter-term AKI patients. Patients with AKD during their ICU stay should be identified to initiate interventions to reduce risk of future MAKEs.

FUNDING

No funding was associated with this study.

Protective effect of estradiol copreservation against kidney ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is the major cause of delayed graft function (DGF) during the posttransplantation period. Estradiol (E2) prevents IRI-induced kidney dysfunction and tissue injury. However, many side effects limit E2's in vivo application. Recent evidence uncovers E2's expanded use in the field of transplantation. We aimed to study if and how E2 exerts protective activity during the period of kidney organ preservation. The autologous kidney transplant model in rats was first established. Rats were divided into 5 groups: normal group (N), sham group (sham), static cold storage (SCS) 4 hours group (control), SCS 4 hours + ethanol (1 µL/mL) group (solvent), and SCS 4 hours + ethanol (1 µL/mL) + E2 (1000 ng/mL) group (E2). ERα expression under hypothermia was measured by western blotting. Moreover, biochemical analyses of plasma levels of creatinine, BUN, estradiol, and testosterone were examined. Among all groups, kidney tissues were collected and processed for further western blot analysis about ERα, eNOS, Bcl-2, and Bax expression, histological analyses such as H&E staining to evaluate pathological severity. In addition, a TUNEL assay is performed to evaluate apoptosis. E2 copreservation upregulated ERα expression under hypothermia. Moreover, E2 copreservation reduced levels of creatinine and BUN in plasma but without affecting estradiol and testosterone. Further, E2 copreservation increased expression of eNOS and antiapoptotic Bcl-2 and decreases expression of proapoptotic Bax. E2 copreservation significantly inhibited IRI-induced apoptosis and evidently improved pathological severity in the kidney of rats. E2 copreservation exerts protective activity against IRI-induced pro-inflammatory and proapoptotic effects in kidneys during organ preservation time and improves transplanted kidney function.

Spatially Resolved Transcriptomic Analysis of Acute Kidney Injury in a Female Murine Model

BACKGROUND

Single-cell sequencing technologies have advanced our understanding of kidney biology and disease, but the loss of spatial information in these datasets hinders our interpretation of intercellular communication networks and regional gene expression patterns. New spatial transcriptomic sequencing platforms make it possible to measure the topography of gene expression at genome depth.

METHODS

We optimized and validated a female bilateral ischemia-reperfusion injury model. Using the 10× Genomics Visium Spatial Gene Expression solution, we generated spatial maps of gene expression across the injury and repair time course, and applied two open-source computational tools, Giotto and SPOTlight, to increase resolution and measure cell-cell interaction dynamics.

RESULTS

An ischemia time of 34 minutes in a female murine model resulted in comparable injury to 22 minutes for males. We report a total of 16,856 unique genes mapped across our injury and repair time course. Giotto, a computational toolbox for spatial data analysis, enabled increased resolution mapping of genes and cell types. Using a seeded nonnegative matrix regression (SPOTlight) to deconvolute the dynamic landscape of cell-cell interactions, we found that injured proximal tubule cells were characterized by increasing macrophage and lymphocyte interactions even 6 weeks after injury, potentially reflecting the AKI to CKD transition.

CONCLUSIONS

In this transcriptomic atlas, we defined region-specific and injury-induced loss of differentiation markers and their re-expression during repair, as well as region-specific injury and repair transcriptional responses. Lastly, we created an interactive data visualization application for the scientific community to explore these results (http://humphreyslab.com/SingleCell/).

The Neglected Price of Pediatric Acute Kidney Injury: Non-renal Implications

Preclinical models and emerging translational data suggest that acute kidney injury (AKI) has far reaching effects on all other major organ systems in the body. Common in critically ill children and adults, AKI is independently associated with worse short and long term morbidity, as well as mortality, in these vulnerable populations. Evidence exists in adult populations regarding the impact AKI has on life course. Recently, non-renal organ effects of AKI have been highlighted in pediatric AKI survivors. Given the unique pediatric considerations related to somatic growth and neurodevelopmental consequences, pediatric AKI has the potential to fundamentally alter life course outcomes. In this article, we highlight the challenging and complex interplay between AKI and the brain, heart, lungs, immune system, growth, functional status, and longitudinal outcomes. Specifically, we discuss the biologic basis for how AKI may contribute to neurologic injury and neurodevelopment, cardiac dysfunction, acute lung injury, immunoparalysis and increased risk of infections, diminished somatic growth, worsened functional status and health related quality of life, and finally the impact on young adult health and life course outcomes.

Thermoneutral Regulation and Acute Injury: Implications for Acute Kidney Injury

Acute kidney injury (AKI) has demonstrated sex differences as illustrated in clinical and preclinical studies. In most cases, females show a significant resistance to AKI as manifested by renal indicators of injury, and thus much of the literature is derived from studies exclusively in males. Thermoneutral housing alters sex differences in acute injury of the liver, but has not been studied in the kidney. Thermoneutrality, the ambient temperature at which additional energy is not needed to maintain core body temperature, is regulated by mechanisms residing in mitochondria. Importantly, mitochondrial function plays an important role in induction and recovery of AKI. Mechanisms that regulate thermoneutrality include uncoupling proteins (UCPs) and one of its upstream regulators peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α). PGC-1α has been extensively studied in AKI in males. UCP-2, a UCP expressed in the kidney, has been minimally studied in AKI in males. Expression of other UCPs in the kidney has not been well defined. No studies of either PGC-1α or UCPs have interrogated for a sex difference nor have they been investigated at thermoneutrality in the kidney. In this brief review, pathways of importance in thermoneutrality are described and related to pathways of importance in modulating susceptibility to AKI. Clarity in the understanding of the impact of thermoneutrality on AKI in altering susceptibility in females may expand our understanding of the critical role of mitochondrial function in this setting. Unique utilization of mitochondrial-based molecular pathways in females may then inform potential therapies.

Risk of Postoperative Renal Failure in Radical Nephrectomy and Nephroureterectomy: A Validated Risk Prediction Model

INTRODUCTION

The study aimed to construct and validate a risk prediction model for incidence of postoperative renal failure (PORF) following radical nephrectomy and nephroureterectomy.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database years 2005-2014 were used for the derivation cohort. A stepwise multivariate logistic regression analysis was conducted, and the final model was validated with an independent cohort from the ACS-NSQIP database years 2015-2017.

RESULTS

In cohort of 14,519 patients, 296 (2.0%) developed PORF. The final 9-factor model included age, gender, diabetes, hypertension, BMI, preoperative creatinine, hematocrit, platelet count, and surgical approach. Model receiver-operator curve analysis provided a C-statistic of 0.79 (0.77, 0.82; p < 0.001), and overall calibration testing R2 was 0.99. Model performance in the validation cohort provided a C-statistic of 0.79 (0.76, 0.81; p < 0.001).

CONCLUSION

PORF is a known risk factor for chronic kidney disease and cardiovascular morbidity, and is a common occurrence after unilateral kidney removal. The authors propose a robust and validated risk prediction model to aid in identification of high-risk patients and optimization of perioperative care.

Sirtuin-3 mediates sex differences in kidney ischemia-reperfusion injury

Studies suggest that biological sex influences susceptibility to kidney diseases with males demonstrating greater risk for developing ischemic acute kidney injury (AKI). Sex-related differences in mitochondrial function and homeostasis exist, likely contributing to sexual dimorphism in kidney injury, but the mechanisms are not well characterized. Our observations reveal lower baseline expression of Sirtuin-3 (Sirt3, a major mitochondrial acetyltransferase) in the kidneys of male mice versus females. We tested the hypothesis that differential expression of kidney Sirt3 may mediate sexual dimorphism in AKI using a bilateral kidney ischemia-reperfusion injury (IRI) model and three transgenic mouse models: (1) mice with global transgenic overexpression of Sirt3; (2) mice with inducible, kidney tubule-specific Sirt3 knockdown (iKD); and (3) mice with global Sirt3 knockout. Low mitochondrial Sirt3 (mtSirt3) in males versus females is associated with development of kidney tubular epithelium vacuoles, increased mitochondrial ROS and susceptibility to IRI. Transgenic overexpression of Sirt3 in males protects against kidney IRI and development of tubular epithelium vacuoles. In both sexes, mice with partial kidney tubular epithelium-specific Sirt3 knockdown display intermediate - while global Sirt3 knockout mice display the highest susceptibility to IRI. Female Sirt3 iKD mice demonstrate decreased survival and kidney function after IRI indistinguishable from control males, abolishing the protective effects observed in females. Mechanistically, observed differences in kidney mtSirt3 are sex hormone-dependent; estradiol increases - while testosterone decreases mtSirt3 protein. Our results demonstrate that Sirt3 is an important contributor to the observed sex-related differences in IRI susceptibility, and a potential therapeutic target in the clinical management of AKI.

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.

Influence of age on gender-related differences in acute kidney injury after minimally invasive radical or partial nephrectomy

BACKGROUND

Female gender is known to be protective against acute kidney injury (AKI) after radical or partial nephrectomy and estrogen is considered a protective factor. If estrogen is a major contributor to the protective effects of female gender against renal injury, these protective effects may be diminished in postmenopausal women. Therefore, this retrospective study investigated the influence of female age on gender-related differences in AKI after minimally invasive radical or partial nephrectomy.

METHODS

Patients who underwent minimally invasive radical (n = 765) or partial (n = 1161) nephrectomy were selected. These patients were stratified by gender and divided into three age categories considered to be pre, peri, and postmenopausal periods in women: ≤ 40 years, 41-59 years, and ≥ 60 years, respectively. Adjusted logistic regression analyses were conducted to identify the risk of AKI according to gender and age.

RESULTS

The incidence of AKI after radical or partial nephrectomy was significantly higher in men as compared to women in all age categories. Women aged ≥ 60 years had a significantly increased risk of AKI as compared to women aged < 60 years in radical nephrectomy, but not in partial nephrectomy. When compared with women aged ≥ 60 years, men aged > 40 years accompanied significantly higher risk of AKI following both radical and partial nephrectomy, even after adjusting confounders. However, men aged ≤ 40 years had a similar risk of AKI after radical nephrectomy, but a significantly higher risk after partial nephrectomy as compared to women aged ≥ 60 years.

CONCLUSION

Male gender was associated with a higher risk of AKI after radical and partial nephrectomy as compared to postmenopausal women. This calls for more thorough preoperative counseling and renal protective strategies in male patients when undergoing radical and partial nephrectomy.

Immune checkpoint inhibitor-associated acute kidney injury and mortality: An observational study

BACKGROUND

Immune checkpoint inhibitors, approved for the treatment of various types of cancer, are known to cause a unique spectrum of side effects, including acute kidney injury (AKI). The aim of this study was to describe the incidence, risk factors, renal outcomes, and mortality of AKI in patients receiving checkpoint inhibitors.

METHODS

Patients receiving checkpoint inhibitors between January 2013 and May 2020 at the University Medical Center Utrecht, the Netherlands, were identified using the Utrecht Patient Oriented Database. AKI was defined as an increase in serum creatinine of ≥1.5 times the baseline value, based on the Kidney Disease: Improving Global Outcomes criteria. Cox proportional hazard regression analysis was used to assess risk factors for AKI and to evaluate the relationship between AKI and mortality. Persistent renal dysfunction was diagnosed in AKI patients with a final serum creatinine measurement of >1.3 times the baseline value.

RESULTS

Among 676 patients receiving checkpoint inhibitors, the overall incidence of AKI was 14.2%. Baseline variables independently associated with AKI were a gynecologic malignancy, monotherapy with ipilimumab, and the use of a diuretic, angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker, or proton pump inhibitor at baseline. AKI was checkpoint inhibitor-associated in one third of all patients with AKI. Checkpoint inhibitor-associated AKI was mostly low-grade, occurred a median of 15 weeks after checkpoint inhibitor initiation, and resulted in persistent renal dysfunction in approximately 40% of the patients. Patients with all-cause AKI had a twofold increased mortality risk, but checkpoint inhibitor-associated AKI was not associated with increased mortality.

CONCLUSIONS

In this study, patients receiving checkpoint inhibitors frequently developed AKI due to various etiologies. AKI directly related to the effect of checkpoint inhibitor toxicity did not increase mortality. However, AKI not related to the effect of checkpoint inhibitor toxicity was associated with increased mortality.

Body mass index is an independent predictor of acute kidney injury after urgent aortic arch surgery for acute DeBakey Type I aortic dissection

Background

Aortic arch surgery and obesity are both related to the risk of acute kidney injury. Our hypothesis was that the risk of postoperative acute kidney injury increases as body mass index increases in patients undergoing urgent aortic total arch replacement surgery for acute DeBakey Type I aortic dissection.

Methods

We conducted a retrospective cohort study in Beijing Anzhen Hospital from December 2015 to April 2017. All patients receiving urgent aortic total arch replacement surgery with a frozen elephant trunk implant for acute DeBakey Type I aortic dissection were included. Body mass index was calculated based on height and weight. Acute kidney injury was diagnosed based on the Kidney Disease Improving Global Outcomes standards.

Results

We included 115 consecutive patients in this study. A total of 53.0% (n = 61) of patients had acute kidney injury. The mean age was 47.8 ± 10.7 years, and 25.2% were women. Mean body mass index was 26.2 ± 3.9 kg/m². The results of a univariate analysis showed that BMI, eGFR, CPB time, operative time, intraoperative blood loss, intraoperative amount of PRBCs, and respiratory failure were significantly correlated with AKI. In-hospital mortality was obviously increased in the acute kidney injury group (13.1% vs 1.9%; P = 0.025). Multivariate logistic regression showed that body mass index was associated with postoperative acute kidney injury after adjusting for other confounding factors (odds ratio = 1.16; 95% confidence interval: 1.02–1.33; P = 0.0288). The risk of postoperative AKI in the BMI ≥ 24 kg/m² group was increased by 2.35 times (OR = 3.35, 95% CI: 1.15–9.74; p = 0.0263).

Conclusions

Body mass index was an independent predictor of acute kidney injury after urgent aortic total arch replacement surgery with a frozen elephant trunk implant.

Preoperative Serum GDF-15, Endothelin-1 Levels, and Intraoperative Factors as Short-Term Operative Risks for Patients Undergoing Cardiovascular Surgery

Objectives: The Society of Thoracic Surgeons (STS) risk score is widely used for the risk assessment of cardiac surgery. Serum biomarkers such as growth differentiation factor-15 (GDF-15) and endothelin-1 (ET-1) are also used to evaluate risk. We investigated the relationships between preoperative serum GDF-15, ET-1 levels, and intraoperative factors and short-term operative risks including acute kidney injury (AKI) for patients undergoing cardiovascular surgery. Methods: In total, 145 patients were included in this study (92 males and 53 females, age 68.4 ± 13.2 years). The preoperative STS score was determined, and the serum GDF-15 and ET-1 levels were measured by ELISA. These were related to postoperative risks, including AKI, defined according to the Acute Kidney Injury Network (AKIN) classification criteria. Results: AKI developed in 23% of patients. The GDF-15 and ET-1 levels correlated with the STS score. The STS score and GDF-15 and ET-1 levels all correlated with preoperative eGFR, Alb, Hb, and BNP levels; perioperative data (urine output); ICU stay period; and postoperative admission days. Patients with AKI had longer circulatory pulmonary bypass (CPB) time, and male patients with AKI had higher ET-1 levels than those without AKI. In multivariable logistic regression analysis, the preoperative ET-1 level and CPB time were the independent determinants of AKI, even adjusted by age, sex, and BMI. The preoperative GDF-15 level, CPB time, and RCC transfusion were independent determinants of 30-day mortality plus morbidity. Conclusion: Preoperative GDF-15 and ET-1 levels as well as intraoperative factors such as CPB time may be helpful to identify short-term operative risks for patients undergoing cardiovascular surgery.

MicroRNA in Human Acute Kidney Injury: A Systematic Review Protocol

BACKGROUND

Acute kidney injury (AKI) is a common complication of hospitalization with high morbidity and mortality for which no effective treatments exist and for which current diagnostic tools have limitations for earlier identification. MicroRNAs (miRNAs) are small non-coding RNAs that have been implicated in the pathogenesis of AKI, and some miRNAs have shown promise as therapeutic tools in animal models of AKI. However, less is known about the role of miRNAs in human AKI.

OBJECTIVE

To evaluate the role of miRNAs in human subjects with AKI.

DESIGN

Systematic review and meta-analysis.

MEASUREMENTS

Quantification of miRNA levels from human blood, urine, or kidney biopsy samples, and measures of renal function as defined in the study protocol.

METHODS

A comprehensive search strategy for Ovid MEDLINE All, Embase, Web of Science, and CENTRAL will be developed to identify investigational studies that evaluated the relationship between miRNA levels and human AKI. Primary outcomes will include measurements of kidney function and miRNA levels. Study screening, review and data extraction will be performed independently by 2 reviewers. Study quality and certainty of evidence will be assessed with validated tools. A narrative synthesis will be included and the possibility for meta-analysis will be assessed according to characteristics of clinical and statistical heterogeneity between studies.

LIMITATIONS

These include (1) lack of randomized trials of miRNAs for the prevention or treatment of human AKI, (2) quality of included studies, and (3) sources of clinical and statistical heterogeneity that may affect strength and reproducibility of results.

CONCLUSION

Previous studies of miRNAs in different animal models of AKI have generated strong interest on their use for the prevention and treatment of human AKI. This systematic review will characterize the most promising miRNAs for human research and will identify methodological constraints from miRNA research in human AKI to help inform the design of future studies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020201253.