Sex Differences in Acute Kidney Injury

Menopause-related changes in vascular signaling by sex hormones

Cardiovascular disease (CVD), such as hypertension and coronary artery disease, involves pathological changes in vascular signaling, function, and structure. Vascular signaling is regulated by multiple intrinsic and extrinsic factors that influence endothelial cells, vascular smooth muscle, and extracellular matrix. Vascular function is also influenced by environmental factors including diet, exercise, and stress, as well as genetic background, sex differences, and age. CVD is more common in adult men and postmenopausal women than in premenopausal women. Specifically, women during menopausal transition, with declining ovarian function and production of estrogen (E2) and progesterone, show marked increase in the incidence of CVD and associated vascular dysfunction. Mechanistic research suggests that E2 and E2 receptor signaling have beneficial effects on vascular function including vasodilation, decreased blood pressure, and cardiovascular protection. Also, the tangible benefits of E2 supplementation in improving menopausal symptoms have prompted clinical trials of menopausal hormone therapy (MHT) in CVD, but the results have been inconsistent. The inadequate benefits of MHT in CVD could be attributed to the E2 type, dose, formulation, route, timing, and duration as well as menopausal changes in E2/E2 receptor vascular signaling. Other factors that could affect the responsiveness to MHT are the integrated hormonal milieu including gonadotropins, progesterone, and testosterone, vascular health status, preexisting cardiovascular conditions, and menopause-related dysfunction in the renal, gastrointestinal, endocrine, immune, and nervous systems. Further analysis of these factors should enhance our understanding of menopause-related changes in vascular signaling by sex hormones and provide better guidance for management of CVD in postmenopausal women. SIGNIFICANCE STATEMENT: Cardiovascular disease is more common in adult men and postmenopausal women than premenopausal women. Earlier observations of vascular benefits of menopausal hormone therapy did not materialize in randomized clinical trials. Further examination of the cardiovascular effects of sex hormones in different formulations and regimens, and the menopausal changes in vascular signaling would help to adjust the menopausal hormone therapy protocols in order to enhance their effectiveness in reducing the risk and the management of cardiovascular disease in postmenopausal women.

The role of sex and gender in acute kidney injury-consensus statements from the 33rd Acute Disease Quality Initiative

Sex differences exist in acute kidney injury (AKI), and the role that sex and gender play along the AKI care continuum remains unclear. The 33rd Acute Disease Quality Initiative meeting evaluated available data on the role of sex and gender in AKI and identified knowledge gaps. Data from experimental models, pathophysiology, epidemiology, clinical care, gender, social determinants of health, education, and advocacy were reviewed. Recommendations include incorporating sex and gender into research along the bench-to-bedside spectrum; analyzing sex-stratified results; evaluating the effects of sex chromosomes, hormones, and gender on outcomes; considering fluctuations of hormone levels; studying the impact gender may have on access to care; and developing educational tools to inform patients, providers, and stakeholders. This meeting report summarizes what is known about sex and gender along the AKI care continuum and proposes an agenda for translational discovery to elucidate the role of sex and gender in AKI across the lifespan.

Association between objectively assessed physical activity and kidney function among female agricultural workers in hot environments in Spain

BACKGROUND

Physical activity in hot environments has been associated with impaired kidney function. We aimed to quantify the association between occupational physical activity and kidney function over one work shift in female agricultural workers exposed to environmental heat.

METHODS

We measured occupational physical activity in female berry pickers in Huelva, Spain, using movement intensity, based on vector magnitude units (VMU), and heart rate (HR). For both, we calculated the mean (VMU_mean; HR_mean), standard deviation (VMU_sd; HR_sd), and 3-min 95th percentile (VMU_p95; HR_p95). Environmental heat in greenhouses was estimated using wet bulb globe temperature (WBGT). Kidney function and injury were quantified using pre- and post-shift differences in serum creatinine (SCr_dif), Cystatin C (Cystatin C_dif) and neutrophil gelatinase associated lipocalin (NGAL_dif), respectively. Acute Kidney Injury (AKI) was defined as an increase in post-shift serum creatinine of ≥0.3 mg/dl, or ≥1.5 times pre-shift levels. Heat strain was estimated using the ISO 7933:2004 index. We used linear and logistic regressions.

RESULTS

Ninety women aged 37.4 ± 5.7 years were exposed to a mean WBGT of 25.2 (±3.6)°C and light intensity physical activity (HR_mean of 94 (±9)bpm). Of those, 26 % experienced heat strain, 68 % were dehydrated, and 7 % presented with AKI at the end of the shift. Higher VMU_sd was associated with higher Scr_dif (β: 0.029 (95 % CI: 0.00; 0.058) and meeting the threshold for AKI (OR: 1.6 (95 % CI: 0.8; 3.2)). We observed higher NGAL_dif with higher VMU_mean (β: 1.944 (95 % CI: 0.139; 3.748)) per 100 VMU_mean increase. The positive association between HR_mean and SCr_dif was stronger among women with heat strain (interaction p = 0.033).

CONCLUSIONS AND RELEVANCE

In female harvest workers, high means and variations in VMU over a single one shift worked under hot conditions were associated with kidney injury, as assessed by urinary biomarkers, though there is limited evidence for any change in kidney function. Precautiously, large changes in physical activity intensity over one work shift should be avoided to protect from renal injury.

Risk factors for postoperative acute kidney injury in colorectal cancer: a systematic review and meta-analysis

PURPOSE

To thoroughly examine the risk factors that may predispose patients with colorectal cancer to postoperative acute kidney injury (AKI).

METHODS

To find relevant studies (from the beginning up to May 2024), two researchers searched PubMed, Web of Science, the Cochrane Library, and Embase databases. Two researchers evaluated the quality of the literature using the Newcastle-Ottawa Scale (NOS) and extracted data individually. Data analysis was performed using the Review Manager 5.4.

RESULTS

Our meta-analysis included 23 studies, encompassing a total of 167,904 patients. The identified risk factors for postoperative AKI in colorectal cancer patients were male sex, older age, body mass index (BMI) ≥ 25 kg/m2, hypertension, diabetes mellitus (DM), chronic kidney disease (CKD), hypoalbuminemia, emergency surgery, open surgery, prolonged operation time, American Society of Anesthesiologists (ASA) score ≥ 3, and intraoperative transfusion. In contrast, anemia and elevated creatinine levels did not emerge as significant risk factors for AKI in this population.

CONCLUSION

To mitigate the incidence of postoperative AKI among these patients, healthcare professionals must proactively identify these risk factors and implement appropriate preventive measures.

Sex, Acute Kidney Injury, and Age: A Prospective Cohort Study

RATIONALE & OBJECTIVE

Animal models of kidney disease suggest a protective role for female sex hormones, but some authorities assert that female sex in humans is a risk factor for acute kidney injury (AKI). To better understand the risk of AKI, we studied the strength of association between sex and AKI incidence in hormonally distinct age groups across the life span.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

All patients hospitalized in the Montefiore Health System between October 15, 2015, and January 1, 2019, excluding those with kidney failure or obstetrics diagnoses.

EXPOSURE

Male versus female sex.

OUTCOME

AKI occurring during hospitalization based on KDIGO definitions.

ANALYTICAL APPROACH

Generalized estimating equation logistic regression adjusted for comorbidities, sociodemographic factors, and severity of illness. Analyses were stratified into 3 age categories: 6 months to≤16 years,>16 years to<55 years, and≥55 years.

RESULTS

A total of 132,667 individuals were hospitalized a total of 235,629 times. The mean age was 55.2±23.8 (SD) years. The count of hospitalizations for women was 129,912 (55%). Hospitalization count among Black and Hispanic patients was 71,834 (30.5%) and 24,199 (10.3%), respectively. AKI occurred in 53,926 (22.9%) hospitalizations. In adjusted models, there was a significant interaction between age and sex (P<0.001). Boys and men had a higher risk of AKI across all age groups, an association more pronounced in the age group>16 years to<55 years in which the odds ratio for men was 1.7 (95% CI, 1.6-1.8). This age-based pattern remained consistent across prespecified types of hospitalizations. In a sensitivity analysis, women older than 55 years who received prescriptions for estrogen had lower odds of AKI than those without prescriptions.

LIMITATIONS

Residual confounding.

CONCLUSIONS

The greatest relative risk of AKI for males occurred during ages>16 to<55 years. The lower risk among postmenopausal women receiving supplemental estrogen supports a protective role for female sex hormones.

PLAIN-LANGUAGE SUMMARY

Male sex is a risk factor for acute kidney injury (AKI) in animals, but in human studies this association is not as robust. We studied hospitalizations at a single center to examine the association of hospital-acquired AKI and sex. After controlling for various sources of potential bias and stratifying by age categories through the life course, we observed that men have a higher risk of AKI throughout life. This risk was especially high compared with women of fertile age and older women prescribed estrogen. This pattern was consistent in prespecified subgroups of hospitalizations. These results support a protective role for female sex hormones in the occurrence of hospitalized AKI.

Persistent subclinical renal injury in female rats following renal ischemia-reperfusion injury

The incidence of acute kidney injury (AKI) continues to rise in both men and women. Although creatinine levels return to normal quicker in females following AKI than in males, it remains unclear whether subclinical renal injury persists in young females post-AKI. This study tested the hypothesis that AKI results in subclinical renal injury in females despite plasma creatinine returning to sham levels. For the present study, 12-13-week-old female Sprague-Dawley (SD) rats were randomized to sham or 45-minute warm bilateral ischemia-reperfusion surgery as an experimental model of ischemic AKI. Rats were euthanized 1, 3, 7, 14, or 30 days post-AKI/sham. Plasma creatinine, cystatin C, kidney injury molecule 1 (KIM-1), and NGAL were quantified via assay kits or immunoblotting. Kidneys were processed for histological analysis to assess tubular injury and fibrosis, and for electron microscopy to examine mitochondrial morphology. Immunoblots on kidney homogenates were performed to determine oxidative stress and apoptosis. Plasma creatinine levels were increased 24 hours post-AKI but returned to sham control levels three days post-AKI. However, cystatin C, KIM-1, and NGAL were increased 30 days post-AKI compared with sham. Tubular injury, tubulointerstitial fibrosis, and mitochondrial dysfunction were all increased in 30-day post-AKI rats compared with sham. Additionally, 30-day post-AKI rats had higher p-JNK expression and lower antioxidant enzyme glutathione peroxidase and catalase levels compared with sham. AKI resulted in higher expression of cleaved caspase 3, TUNEL+ cells, and caspase 9 than sham. Despite the normalization of creatinine levels, our data support the hypothesis that subclinical renal injury persists following ischemia-reperfusion injury in young female rats.

Sex-based Differences in Complications Following Percutaneous Coronary Interventions

PURPOSE OF REVIEW

The role that sex plays in the incidence and outcomes of PCI related complications is not well understood. The purpose of this review is to highlight the commonly encountered peri-procedural complications and search for any sex differences in the published literature.

RECENT FINDINGS

Procedure related complications and long-term cardiovascular outcomes remain worse in women. The delayed presentation of women with coronary events and delayed referral for an invasive diagnostic angiogram and subsequent revascularization likely contribute to the worse outcomes. Whether the smaller vessel size, residual Syntax Score, and other biological factors impact periprocedural outcomes is controversial and warrants device and procedure specific research to identify sex differences. Modern day percutaneous revascularization has achieved very high acute procedural success rates and low complication rates with the advent of structured training programs, development of appropriate use criteria and refined devices and technologies in the catheterization laboratory. However, both procedure related complications and long-term cardiovascular outcomes remain worse in women.

Attenuation of acute kidney injury in a murine model of neonatal Escherichia coli sepsis

Introduction

Sepsis is a risk factor for acute kidney injury (AKI) in neonates, for which no effective treatment exists. The phosphodiesterase inhibitor pentoxifylline (PTX) has demonstrated renal protection from ischemia and inflammation in adult rodents. We hypothesized that addition of PTX to antibiotics may attenuate immune and histological AKI in a murine neonatal sepsis model.

Methods

Postnatal (PN) day 1 C57BL/6J mice were injected with E. coli K1 strain at 105 colony forming units per gram weight or saline control. After 1.5 hours, septic pups randomly received saline, gentamicin or cefotaxime, with/without PTX. 5.5h after sepsis initiation, kidneys and blood were harvested for measurements of biomarkers of inflammation and kidney injury. Renal sections from PN7 mice were used for histology and immunofluorescence. Linear mixed effect models were employed to fit the outcomes including interaction between treatment group and sex.

Results

Septic mice demonstrated robust expression of pro-inflammatory cytokines, chemokines and biomarkers of tubular injury in renal tissue, which were attenuated in response to combined PTX and antibiotics (gentamicin or cefotaxime): chemokines (p<0.001), plasma (p<0.01) and tissue IL-6 (p<0.05), plasma TNF (p<0.001), NGAL (p<0.01), CXCL10 (p<0.01), osteopontin (p<0.05), and VEGF (p<0.05), with a trend for KIM-1 (tissue concentration: p=0.21, fluorescence area: p=0.12). Interactions between treatment and sex were present for several cytokines and kidney injury biomarkers. Immunofluorescence findings for the tubular injury markers (NGAL and KIM-1) were consistent with biomarker expression in tissue lysates.

Conclusion

Neonatal E. coli sepsis leads to increased expression of renal tissue inflammation and injury biomarkers consistent with AKI, which may be attenuated with PTX combined with antibiotic treatment.

ACUTE KIDNEY INJURY FOLLOWING ACUTE CHOLANGITIS: A RISK MULTIPLIER FOR ADVERSE OUTCOMES AND HEALTHCARE UTILIZATION

ABSTRACT

Background: Acute kidney injury (AKI) is a common, fatal complication of acute cholangitis (AC). The link between AC and AKI is poorly understood. Aims: To delineate the incidence trends, clinical outcomes and healthcare utilization of inpatients with AKI following AC and to explore the risk factors for AKI following AC. Methods: This population-based retrospective study used the National Inpatient Sample database from 2010 to 2018 to compare the demographics, complications, in-hospital mortality and healthcare utilization between AC patients with and without AKI. Predictors of AKI and the prognostic impact of AKI on in-hospital outcomes were defined using multivariate logistic regression. Results: The overall incidence of AKI was 24.06% among AC patients. Its trend generally increased annually. AKI was associated with more complications, greater invasive therapy requirements, longer hospital stays, costlier total hospital charges, and higher in-hospital mortality. The risk factors for AKI following AC were advanced age, Black race, multiple comorbidities, large hospitals, teaching hospitals, urban hospitals, hospitals in the southern and western United States, choledocholithiasis/cholelithiasis, surgery, percutaneous transhepatic biliary drainage, deficiency anemia, congestive heart failure, coagulopathy, diabetes, hypertension, chronic liver disease, obesity, chronic kidney disease excluding end-stage renal disease, weight loss, acute pancreatitis, and severe sepsis. Female sex, private insurance, elective admission, and endoscopic retrograde cholangiopancreatography were protective factors against AKI in AC patients. Conclusion: AKI often follows AC and is strongly associated with poor prognosis and increased healthcare utilization. Healthcare professionals should make more efforts to identify patients with AC at risk of AKI and start management promptly to limit adverse outcomes.

Chronic kidney disease

Chronic kidney disease (CKD) is defined by persistent abnormalities of kidney function or structure that have consequences for the health. A progressive decline of excretory kidney function has effects on body homeostasis. CKD is tightly associated with accelerated cardiovascular disease and severe infections, and with premature death. Kidney failure without access to kidney replacement therapy is fatal - a reality in many regions of the world. CKD can be the consequence of a single cause, but CKD in adults frequently relates rather to sequential injuries accumulating over the life course or to the presence of concomitant risk factors. The shared pathomechanism of CKD progression is the irreversible loss of kidney cells or nephrons together with haemodynamic and metabolic overload of the remaining nephrons, leading to further loss of kidney cells or nephrons. The management of patients with CKD focuses on early detection and on controlling all modifiable risk factors. This approach includes reducing the overload of the remaining nephrons with inhibitors of the renin-angiotensin system and the sodium-glucose transporter 2, as well as disease-specific drug interventions, if available. Hypertension, anaemia, metabolic acidosis and secondary hyperparathyroidism contribute to cardiovascular morbidity and reduced quality of life, and require diagnosis and treatment.

Sexually dimorphic renal expression of mouse 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 present 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.

Sex-disaggregated analysis of acute kidney injury in hospitalized children with sickle cell anemia in Uganda

A growing body of research is categorizing sex differences in both sickle cell anemia (SCA) and acute kidney injury (AKI); however, most of this work is being conducted in high-resource settings. Here, we evaluated risk factors and clinical parameters associated with AKI and AKI severity, stratified by sex, in a cohort of children hospitalized with SCA and vaso-occlusive pain crisis (VOC). The purpose of this study was to explore sex disparities in a high-risk, vulnerable population. This study was a secondary analysis of data collected from a cohort of Ugandan children between 2 and 18 yr of age prospectively enrolled. A total of 185 children were enrolled in the primary study; 41.6% were female and 58.4% were male, with a median age of 8.9 yr. Incident or worsening AKI (P = 0.026) occurred more frequently in female compared with male children, despite no differences in AKI on admission. Female children also had altered markers of renal function including higher creatinine levels at admission (P = 0.03), higher peak creatinine (P = 0.006), and higher urine neutrophil gelatinase-associated lipocalin (NGAL) at admission (P = 0.003) compared with male children. Female children had elevated total (P = 0.045) and conjugated bilirubin at admission (P = 0.02) compared with male children and higher rates of hematuria at admission (P = 0.004). Here, we report sex differences in AKI in children with SCA and VOC, including increased incidence and worsening of AKI in female pediatric patients, in association with an increase in biological indicators of poor renal function including creatinine, estimated glomerular filtration rate, and NGAL.NEW & NOTEWORTHY In this study, we report an increased risk of developing acute kidney injury (AKI) during hospitalization, worsening AKI, and death among females with sickle cell anemia (SCA) hospitalized with an acute pain crisis compared with males. The sex differences in AKI were not explained by socioeconomic differences, severity of pain, or disease severity among females compared with males. Together, these data suggest that female children with SCA may be at increased risk of AKI.

Acute kidney injury, the present on admission (POA) indicator and sex disparities: observational study of inpatient real-world data in a Swiss tertiary healthcare system. Explorative analysis

Background

Regarding kidney disease (KD), sex differences in epidemiology and clinical relevance have been reported. Related to absolute and relative changes of baseline creatinine, different criteria for staging may induce underdiagnosis or overdiagnosis related to sex. At the largest Swiss provider of inpatient acute healthcare, a clinic decision support algorithm ensures exact staging of KD (2012 KDIGO Kidney Disease Improving Global Outcomes Clinical Practice Guideline). Coding of the indicator 'Present On Admission' (POA) was introduced at this institution in 2018 to flag postadmission conditions.

Objective

The explorative analysis aimed at differences in diagnosis groups. Defined indicators and the distribution of stages in acute kidney injury (AKI) were analysed using the POA flag. Sex differences were reported.

Methods

Retrospective observational study. Explorative analysis. Routinely collected health data, 2019 and 2020 (121 757 cases) on the patient history and intensive care treatment duration, comorbidity levels, coded diagnoses, age and sex.Software and statistic: program R, V.4.1.1, SD; median, IQR; prop.test; standardised mean difference.

Results

The reporting of postadmission diagnoses showed more interhospital transfers, more intensive care stays, higher scores of severity and treatment intensity, more often mechanical ventilation, a higher age, a higher number of diagnoses, a higher complexity level of the related cases and mortality. This observation could be made to a lesser degree for the female population. However, for the female population mortality was higher (stage III AKI 41.6%).

Conclusion

Using the POA flag, the results reflect the clinical situation of complications and comorbidities evolving unexpectedly. As our results show sex differences, that is, a lower morbidity of female patients for each stage, but a higher mortality, a deeper evaluation of the implied sex differences in staging of KD should follow.The general results confirm the necessity of a diagnosis-onset reporting in health statistics.

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.

High resolution spatial profiling of kidney injury and repair using RNA hybridization-based in situ sequencing

Emerging spatially resolved transcriptomics technologies allow for the measurement of gene expression in situ at cellular resolution. We apply direct RNA hybridization-based in situ sequencing (dRNA HybISS, Cartana part of 10xGenomics) to compare male and female healthy mouse kidneys and the male kidney injury and repair timecourse. A pre-selected panel of 200 genes is used to identify cell state dynamics patterns during injury and repair. We develop a new computational pipeline, CellScopes, for the rapid analysis, multi-omic integration and visualization of spatially resolved transcriptomic datasets. The resulting dataset allows us to resolve 13 kidney cell types within distinct kidney niches, dynamic alterations in cell state over the course of injury and repair and cell-cell interactions between leukocytes and kidney parenchyma. At late timepoints after injury, C3+ leukocytes are enriched near pro-inflammatory, failed-repair proximal tubule cells. Integration of snRNA-seq dataset from the same injury and repair samples also allows us to impute the spatial localization of genes not directly measured by dRNA HybISS.

Hyaluronidase inhibitor sHA2.75 alleviates ischemia-reperfusion-induced acute kidney injury

Hyaluronidases (HAases) are enzymes that degrade hyaluronic acid (HA) in the animal kingdom. The HAases-HA system is crucial for HA homeostasis and plays a significant role in biological processes and extracellular matrix (ECM)-related pathophysiological conditions. This study aims to explore the role of inhibiting the HAases-HA system in acute kidney injury (AKI). We selected the potent inhibitor "sHA2.75" to inhibit HAase activity through mixed inhibitory mechanisms. The ischemia-reperfusion mouse model was established using male BALB/c mice (7-9 weeks old), and animals were subjected to subcapsular injection with 50 mg/kg sHA2.75 twice a week to evaluate the effects of sHA2.75 on AKI on day 1, 5 and 14 after ischemia-reperfusion or sham procedure. Blood and tissue samples were collected for immunohistochemistry, biochemical, and quantitative analyses. sHA2.75 significantly reduced blood urea nitrogen (BUN) and serum creatinine levels in AKI mouse models. Expression of kidney injury-related genes such as Kidney injury molecule-1 (KIM-1), Neutrophil Gelatinase-Associated Lipocalin (NGAL), endothelial nitric oxide synthase (eNOS), type I collagen (Col1), type III collagen (Col3), alpha-smooth muscle actin (α-SMA) showed significant downregulation in mouse kidney tissues after sHA2.75 treatment. Moreover, sHA2.75 treatment led to decreased plasma levels of Interleukin-6 (IL-6) proteins and reduced mRNA levels in renal tissues of AKI mice. Inhibitor sHA2.75 administration in the AKI mouse model downregulated kidney injury-related biomarkers and immune-specific genes, thereby alleviating AKI in vivo. These findings suggest the potential use of HAase inhibitors for treating ischemic reperfusion-induced kidney injury.

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.

T-cells regulate albuminuria but not hypertension, renal histology, or the medullary transcriptome in the Dahl SSCD247+/+ rat

In the current study, we took advantage of the loss of protection from hypertension in SSCD247-/- rats to characterize the pathological effects of renal T-cells in isolation from the confounding effects of elevated renal perfusion pressure. Male SSCD247-/- and SSCD247+/+ littermates were fed 4.0% NaCl (high salt) diet to induce hypertension. Blood pressure was assessed continuously throughout the time course with radiotelemetry. Urine albumin and protein excretion were assessed on the final day of high salt. Renal injury and medullary transcriptome were assessed after completion of the high salt protocol. In contrast to previous studies, mean arterial pressure was not significantly different between SSCD247-/- and SSCD247+/+ rats. Despite this lack of pressure difference, urinary albumin was significantly lower in SSCD247-/- rats than their wild-type littermates. In the outer medulla, substantially more transcriptomic changes were found to correlate with endpoint blood pressure than with the absence of presence of renal T-cells. We also demonstrated that renal histological damage was driven by elevated renal perfusion pressure rather than the presence of renal T-cells. In conclusion, using the loss of protection from hypertension in SSCD247-/- rats, we demonstrated that renal perfusion pressure has more profound pathological effects on the kidney than renal T-cells. However, renal T-cells, independently of blood pressure, modulate the progression of albuminuria.NEW & NOTEWORTHY In vivo studies in a T-cell-deficient rat model of salt-sensitive hypertension (SSCD247-/- rats) were used to evaluate the role of T-cells on the development of hypertension and renal damage. Detailed physiological and transcriptomic analysis demonstrated no difference in blood pressure between rats with (SSCD247+/+) or without (SSCD247-/-) T-cells. Despite this, albuminuria was significantly lower in SSCD247-/- rats than SSCD247+/+ rats.

Healthy Women Have Higher Systemic Uromodulin Levels: Identification of Uromodulin as an Estrogen Responsive Gene

Serum uromodulin levels are higher in healthy female participants than healthy male participants. Serum uromodulin levels in participants with normal kidney function do not correlate with eGFR but do correlate with body mass index. Estrogen increases uromodulin production, likely because of noncanonical and half estrogen response elements in the UMOD gene.

Gender-based research underscores sex differences in biological processes, clinical disorders and pharmacological interventions

Earlier research has presumed that the male and female biology is similar in most organs except the reproductive system, leading to major misconceptions in research interpretations and clinical implications, with serious disorders being overlooked or misdiagnosed. Careful research has now identified sex differences in the cardiovascular, renal, endocrine, gastrointestinal, immune, nervous, and musculoskeletal systems. Also, several cardiovascular, immunological, and neurological disorders have shown differences in prevalence and severity between males and females. Genetic variations in the sex chromosomes have been implicated in several disorders at young age and before puberty. The levels of the gonadal hormones estrogen, progesterone and testosterone and their receptors play a role in the sex differences between adult males and premenopausal women. Hormonal deficiencies and cell senescence have been implicated in differences between postmenopausal and premenopausal women. Specifically, cardiovascular disorders are more common in adult men vs premenopausal women, but the trend is reversed with age with the incidence being greater in postmenopausal women than age-matched men. Gender-specific disorders in females such as polycystic ovary syndrome, hypertension-in-pregnancy and gestational diabetes have attained further research recognition. Other gender-related research areas include menopausal hormone therapy, the "Estrogen Paradox" in pulmonary arterial hypertension being more predominant but less severe in young females, and how testosterone may cause deleterious effects in the kidney while having vasodilator effects in the coronary circulation. This has prompted the National Institutes of Health (NIH) initiative to consider sex as a biological variable in research. The NIH and other funding agencies have provided resources to establish state-of-the-art centers for women health and sex differences in biology and disease in several academic institutions. Scientific societies and journals have taken similar steps to organize specialized conferences and publish special issues on gender-based research. These combined efforts should promote research to enhance our understanding of the sex differences in biological systems beyond just the reproductive system, and provide better guidance and pharmacological tools for the management of various clinical disorders in a gender-specific manner.

Sex differences in long-term kidney fibrosis following neonatal nephron loss during ongoing nephrogenesis

BACKGROUND

Clinical studies suggest that female sex plays a protective role in the development and progression of kidney disease. Recent experimental studies indicate that in male rats early nephron loss under ongoing nephrogenesis is accompanied by severe long-term sequelae. In humans, nephron formation occurs mainly in the third trimester, ceasing with 36 weeks of gestation. Due to perinatal complications, preterm infants delivered during this vulnerable period may undergo acute nephron loss. In rats nephrogenesis persists until postnatal day 10, reflecting the situation of human preterms with persisting nephrogenesis. In our animal model of neonatal uninephrectomy, female and male rats were uninephrectomized at day 1 of life. Hypothesizing sex-dependent differences, long-term renal outcome was assessed after 1 year.

RESULTS

In both sexes, neonatal uninephrectomy was not followed by arterial hypertension at 1 year of age. Compensatory weight gain and glomerular hypertrophy of the remaining kidney occurred in uninephrectomized female and male animals. Selected markers of interstitial inflammation and fibrosis were regulated sex-dependently. The expression of monocyte chemoattractant protein-1 was increased in females, while tubulointerstitial infiltration by M1 macrophages was significantly higher in males after neonatal uninephrectomy. Neonatally uninephrectomized male rats had more glomerulosclerosis and podocyte damage compared to females, which was assessed by a semiquantitative score and desmin staining. RT-PCR revealed that after neonatal uninephrectomy in the remaining contralateral kidney of female rats the expression of candidate genes of renal development and function, i.e., wt-1, nephrin, synaptopodin, gdnf, and itga8 was higher than in males.

CONCLUSIONS

Based on these observations we conclude that female sex is protective in the long-term response of the kidney to acute nephron loss under active nephrogenesis.

Kidney transcriptome and cystic kidney disease genes in zebrafish

Introduction: Polycystic kidney disease (PKD) is a condition where fluid filled cysts form on the kidney which leads to overall renal failure. Zebrafish has been recently adapted to study polycystic kidney disease, because of its powerful embryology and genetics. However, there are concerns on the conservation of this lower vertebrate in modeling polycystic kidney disease. Methods: Here, we aim to assess the molecular conservation of zebrafish by searching homologues polycystic kidney disease genes and carrying transcriptome studies in this animal. Results and Discussion: We found that out of 82 human cystic kidney disease genes, 81 have corresponding zebrafish homologs. While 75 of the genes have a single homologue, only 6 of these genes have two homologs. Comparison of the expression level of the transcripts enabled us to identify one homolog over the other homolog with >70% predominance, which would be prioritized for future experimental studies. Prompted by sexual dimorphism in human and rodent kidneys, we studied transcriptome between different sexes and noted significant differences in male vs. female zebrafish, indicating that sex dimorphism also occurs in zebrafish. Comparison between zebrafish and mouse identified 10% shared genes and 38% shared signaling pathways. String analysis revealed a cluster of genes differentially expressed in male vs. female zebrafish kidneys. In summary, this report demonstrated remarkable molecular conservation, supporting zebrafish as a useful animal model for cystic kidney disease.

Increase in Registered Acute Kidney Injuries in German Hospitals

BACKGROUND

Currently, the development of the incidence of acute kidney injury (AKI) and the influence of age and gender on the condition in Germany is unclear.

MATERIALS AND METHODS

Data were extracted from the national database of Federal Health Reporting. It was then normalized for demographic changes. Poisson regression was performed on 933,684 cases to quantify the correlation between age, years, and AKI incidence. Analysis of variance was performed on the same collection to evaluate gender disparities in different age groups.

RESULTS

In absolute numbers, registered AKI increased almost sevenfold from 11,964 to 77,719 between 2000 and 2019. After adjusting for demographic changes, the most AKI - 6300.5 per million person-years - occur in the elderly (>79 years old). Males have a higher risk for the development of an AKI. The male and female AKI incidence ratio varies significantly between different age groups, and it is the lowest in people <20 and >79 years old.

CONCLUSIONS

The registered incidence of AKI has risen substantially in the first 20 years of the millennium. The increase can partly be attributed to an increased diagnostic sensitivity provided by changes in the classification of AKI. It could also be shown that men suffer from AKI more often than women, particularly in the younger age groups.

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.

The effect of interval and continuous work on markers of acute kidney injury in a hot environment

PURPOSE

To examine the effect of high-intensity interval work (HIIW) and moderate-intensity continuous work (MICW) on markers of acute kidney injury (AKI) and kidney function in a hot environment.

METHODS

Nine males completed 2 h of work (2 × 60 min with 10 min passive rest) in a hot environment (40 °C and 15% relative humidity) as either HIIW [2 min at 80% peak oxygen consumption (VO₂peak) and 3 min at 30% VO₂peak] or MICW (matched for total work of HIIW). Blood and urine samples were collected immediately before (Pre), after (Post), 1 h (1 h Post), and 24 h after (24 h Post) the trials. Urine flow rate (UFR), creatinine clearance, insulin-like growth factor binding protein 7 (IGFBP7), urinary neutrophil gelatinase-associated lipocalin (uNGAL), and urinary kidney injury marker 1 (uKIM-1) were measured to assess kidney function and injury.

RESULTS

Log IGFBP7 (p < 0.01), log uNGAL (p < 0.01), and log uKIM-1 (p = 0.01) all displayed a main effect for time after both HIIW and MICW. IGFBP7 (p = 0.01) and uKIM-1 (p < 0.01), corrected for Uosm, were higher after HIIW compared to MICW at Post, while IGFBP7 was also higher 1 h Post after HIIW compared to MICW (p = 0.02). UFR significantly decreasing from Pre to Post (p < 0.01) and 1 h Post (p < 0.01), but no main effect for condition (p = 0.53).

CONCLUSION

Both HIIW and MICW in a hot environment caused an increase in biomarkers of kidney injury (IGFBP7, KIM-1, and NGAL), but HIIW may have a greater impact on biomarkers related to AKI.