Mitochondrial dysfunction in acute kidney injury and sex-specific implications

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.

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.

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.

Pathophysiology of Acute Kidney Frailty

Acute kidney frailty is a premorbid condition of diminished renal functional reserve that predisposes to acute kidney injury; this condition results from subclinical wear or distortion of renal homeostatic responses that protect the renal excretory function. Knowledge of its pathophysiological basis is critical for the development of diagnostic and therapeutic strategies that allow for prophylactic intervention and disease prevention.

The Activation of cGAS-STING in Acute Kidney Injury

The activation of the cGAS-STING pathway is associated with many sterile inflammatory and inflammatory conditions, including acute kidney injury. As a cytoplasmic DNA sensor, sensitization of the cGAS-STING pathway can ignite the innate immune response in vivo and trigger a series of biological effects. In recent years, there is increasing evidence showing that the cGAS-STING pathway plays a vital role in acute kidney injury, a non-inflammatory disease induced by activation of innate immune cells, and closely related to intracellular reactive oxygen species, mitochondrial DNA, and the cGAS-STING pathway. This review provides a prospect of the cGAS-STING pathway and its relationship to acute kidney injury.

Identification of signature genes for renal ischemia‒reperfusion injury based on machine learning and WGCNA

Background

As an inevitable event after kidney transplantation, ischemia‒reperfusion injury (IRI) can lead to a decrease in kidney transplant success. The search for signature genes of renal ischemia‒reperfusion injury (RIRI) is helpful in improving the diagnosis and guiding clinical treatment.

Methods

We first downloaded 3 datasets from the GEO database. Then, differentially expressed genes (DEGs) were identified and applied for functional enrichment analysis. After that, we performed three machine learning methods, including random forest (RF), Lasso regression analysis, and support vector machine recursive feature elimination (SVM-RFE), to further predict candidate genes. WGCNA was also executed to screen candidate genes from DEGs. Then, we took the intersection of candidate genes to obtain the signature genes of RIRI. Receiver operating characteristic (ROC) analysis was conducted to measure the predictive ability of the signature genes. Kaplan‒Meier analysis was used for association analysis between signature genes and graft survival. Verifying the expression of signature genes in the ischemia cell model.

Results

A total of 117 DEGs were screened out. Subsequently, RF, Lasso regression analysis, SVM-RFE and WGCNA identified 17, 25, 18 and 74 candidate genes, respectively. Finally, 3 signature genes (DUSP1, FOS, JUN) were screened out through the intersection of candidate genes. ROC analysis suggested that the 3 signature genes could well diagnose and predict RIRI. Kaplan‒Meier analysis indicated that patients with low FOS or JUN expression had a longer OS than those with high FOS or JUN expression. Finally, we validated using the ischemia cell model that compared to the control group, the expression level of JUN increased under hypoxic conditions.

Conclusions

Three signature genes (DUSP1, FOS, JUN) offer a good prediction for RIRI outcome and may serve as potential therapeutic targets for RIRI intervention, especially JUN. The prediction of graft survival by FOS and JUN may improve graft survival in patients with RIRI.

Benefits of high-intensity interval training compared to continuous training to reduce apoptotic markers in female rats with cisplatin nephrotoxicity - possible modulatory role of IL-11

Apoptotic signaling pathways are involved in acute kidney injury (AKI) induced by the antineoplastic drug cisplatin (Cis). Mechanical stress is known to increase interleukin (IL) -11, a pleiotropic cytokine with antiapoptotic and antinecrotic effects. We compared the impact of high-intensity interval training (HIIT) with low-intensity continuous training (LICT) and moderate-intensity continuous training (MICT) on renal levels of IL-11 and the expression of apoptotic markers in female rats with nephrotoxicity induced by Cis. For that, the animals were divided into five groups (n = 7): control and sedentary (C + S); Cis and sedentary (Cis + S); Cis and LICT (Cis + LICT); Cis and MICT (Cis + MICT) and Cis and HIIT (Cis + HIIT). At the end of 8 weeks of treadmill running, the rats received a single injection of Cis (5 mg/kg), and 7 days later they were euthanized. Serum and kidney samples were collected to assess the blood urea nitrogen (BUN), gene expression of TNF receptor 1 (TNFR1) and 2 (TNFR2), caspase-3, (p38) MAPK (MAPK14), p53, Bax, Bak, Bcl-2, and Bcl-xL, renal levels of IL-11, IL-8, and p53, and immunolocalization of cleaved caspase-3, Bax, Bcl-2, and (p38) MAPK in renal tissue. Our data indicate that all trained groups showed a significant intensity-dependent increase in renal levels of IL-11 associated with reduced local expression of proapoptotic and increased antiapoptotic markers, but these effects were more pronounced with HIIT. So, HIIT appears to provide superior renoprotection than traditional continuous training by modulating apoptotic signaling pathways, and this effect can be related to the increase in renal levels of IL-11.

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].

Estradiol Ameliorates Acute Kidney Ischemia-Reperfusion Injury by Inhibiting the TGF-βRI-SMAD Pathway

Renal ischemia–reperfusion injury (IRI) is less extensive in females than males in both animals and humans; however, this protection diminishes after menopause, suggesting that estrogen plays a pivotal role in IRI, but the underlying mechanism remains largely unknown. Our study found that 45 min of warm ischemia was sufficient to induce significant pathological changes without causing death in model animals. Compared with male rats, female rats exhibited less extensive apoptosis, kidney injury, and fibrosis; these effects were worsened in ovariectomized (OVX) rats and ameliorated upon estradiol (E₂) supplementation. Furthermore, the levels of TGF-βRI, but not TGF-βRII or TGF-β1, were significantly increased in OVX rats, accompanied by phosphorylated SMAD2/3 activation. Interestingly, the alteration trend of the nuclear ERα level was opposite that of TGF-βRI. Furthermore, dual luciferase reporter and chromatin immunoprecipitation assays showed that ERα could bind to the promoter region of TGF-βRI and negatively regulate its mRNA expression. Moreover, an in vitro study using NRK-52E cells showed that ERα knockdown blocked E₂-mediated protection, while TGF-βRI knockdown protected cells against hypoxic insult. The findings of this study suggest that renal IRI is closely related to the TGF-βRI-SMAD pathway in females and that E₂ exert its protective effect via the ERα-mediated transcriptional inhibition of TGF-βRI expression.

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.

Sex-related differences in diabetic kidney disease: A review on the mechanisms and potential therapeutic implications

Sexual dimorphism may play a key role in the pathogenesis of diabetic kidney disease (DKD) and explain differences observed in disease phenotypes, responses to interventions, and disease progression between men and women with diabetes. Therefore, omitting the consideration of sex as a biological factor may result in delayed diagnoses and suboptimal therapies. This review will summarize the effects of sexual dimorphism on putative metabolic and molecular mechanisms underlying DKD, and the potential implications of these differences on therapeutic interventions. To successfully implement precision medicine, we require a better understanding of sexual dimorphism in the pathophysiologic progression of DKD. Such insights can unveil sex-specific therapeutic targets that have the potential to maximize efficacy while minimizing adverse events.

Human antigen R regulates hypoxia-induced mitophagy in renal tubular cells through PARKIN/BNIP3L expressions

Mitochondrial dysfunction contributes to the pathophysiology of acute kidney injury (AKI). Mitophagy selectively degrades damaged mitochondria and thereby regulates cellular homeostasis. RNA-binding proteins (RBPs) regulate RNA processing at multiple levels and thereby control cellular function. In this study, we aimed to understand the role of human antigen R (HuR) in hypoxia-induced mitophagy process in the renal tubular cells. Mitophagy marker expressions (PARKIN, p-PARKIN, PINK1, BNIP3L, BNIP3, LC3) were determined by western blot analysis. Immunofluorescence studies were performed to analyze mitophagosome, mitolysosome, co-localization of p-PARKIN/TOMM20 and BNIP3L/TOMM20. HuR-mediated regulation of PARKIN/BNIP3L expressions was determined by RNA-immunoprecipitation analysis and RNA stability experiments. Hypoxia induced mitochondrial dysfunction by increased ROS, decline in membrane potential and activated mitophagy through up-regulated PARKIN, PINK1, BNIP3 and BNIP3L expressions. HuR knockdown studies revealed that HuR regulates hypoxia-induced mitophagosome and mitolysosome formation. HuR was significantly bound to PARKIN and BNIP3L mRNA under hypoxia and thereby up-regulated their expressions through mRNA stability. Altogether, our data highlight the importance of HuR in mitophagy regulation through up-regulating PARKIN/BNIP3L expressions in renal tubular cells.

Gender-biased kidney damage in mice following exposure to tobacco cigarette smoke: More protection in premenopausal females

Multiple clinical studies documented renal damage in chronic cigarette smokers (CS) irrespective of their age and gender. Premenopausal female smokers are known to exert a certain cardiovascular and renal protection with undefined mechanisms. Given the multiple demographic variables within clinical studies, this experimental study was designed to be the first to assess whether gender‐biased CS‐induced kidney damage truly exists between premenopausal female and age‐matched C57Bl6J male mice when compared to their relative control groups. Following 6 weeks of CS exposure, cardiac function, inflammatory marker production, fibrosis formation, total and glomerular ROS levels, and glomerulotubular homeostasis were assessed in both genders. Although both CS‐exposed male and female mice exhibited comparable ROS fold change relative to their respective control groups, CS‐exposed male mice showed a more pronounced fibrotic deposition, inflammation, and glomerulotubular damage profile. However, the protection observed in CS‐exposed female group was not absolute. CS‐exposed female mice exhibited a significant increase in fibrosis, ROS production, and glomerulotubular alteration but with a pronounced anti‐inflammatory profile when compared to their relative control groups. Although both CS‐exposed genders presented with altered glomerulotubular homeostasis, the alteration phenotype between genders was different. CS‐exposed males showed a significant decrease in Bowman's space along with reduced tubular diameter consistent with an endocrinization pattern of chronic tubular atrophy, suggestive of an advanced stage of glomerulotubular damage. CS‐exposed female group, on the other hand, displayed glomerular hypertrophy with a mild tubular dilatation profile suggestive of an early stage of glomerulotubular damage that generally precedes collapse. In conclusion, both genders are prone to CS‐induced kidney damage with pronounced female protection due to a milder damage slope.

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

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

α1-Microglobulin (A1M) Protects Human Proximal Tubule Epithelial Cells from Heme-Induced Damage In Vitro

Oxidative stress is associated with many renal disorders, both acute and chronic, and has also been described to contribute to the disease progression. Therefore, oxidative stress is a potential therapeutic target. The human antioxidant α₁-microglobulin (A1M) is a plasma and tissue protein with heme-binding, radical-scavenging and reductase activities. A1M can be internalized by cells, localized to the mitochondria and protect mitochondrial function. Due to its small size, A1M is filtered from the blood into the glomeruli, and taken up by the renal tubular epithelial cells. A1M has previously been described to reduce renal damage in animal models of preeclampsia, radiotherapy and rhabdomyolysis, and is proposed as a pharmacological agent for the treatment of kidney damage. In this paper, we examined the in vitro protective effects of recombinant human A1M (rA1M) in human proximal tubule epithelial cells. Moreover, rA1M was found to protect against heme-induced cell-death both in primary cells (RPTEC) and in a cell-line (HK-2). Expression of stress-related genes was upregulated in both cell cultures in response to heme exposure, as measured by qPCR and confirmed with in situ hybridization in HK-2 cells, whereas co-treatment with rA1M counteracted the upregulation. Mitochondrial respiration, analyzed with the Seahorse extracellular flux analyzer, was compromised following exposure to heme, but preserved by co-treatment with rA1M. Finally, heme addition to RPTE cells induced an upregulation of the endogenous cellular expression of A1M, via activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)-pathway. Overall, data suggest that A1M/rA1M protects against stress-induced damage to tubule epithelial cells that, at least partly, can be attributed to maintaining mitochondrial function.

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

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

Metabolic Flexibility and Innate Immunity in Renal Ischemia Reperfusion Injury: The Fine Balance Between Adaptive Repair and Tissue Degeneration

Renal ischemia reperfusion injury (IRI), a common event after renal transplantation, causes acute kidney injury (AKI), increases the risk of delayed graft function (DGF), primes the donor kidney for rejection, and contributes to the long-term risk of graft loss. In the last decade, epidemiological studies have linked even mild episodes of AKI to chronic kidney disease (CKD) progression, and innate immunity seems to play a crucial role. The ischemic insult triggers an acute inflammatory reaction that is elicited by Pattern Recognition Receptors (PRRs), expressed on both infiltrating immune cells as well as tubular epithelial cells (TECs). Among the PRRs, Toll-like receptors (TLRs), their synergistic receptors, Nod-like receptors (NLRs), and the inflammasomes, play a pivotal role in shaping inflammation and TEC repair, in response to renal IRI. These receptors represent promising targets to modulate the extent of inflammation, but also function as gatekeepers of tissue repair, protecting against AKI-to-CKD progression. Despite the important considerations on timely use of therapeutics, in the context of IRI, treatment options are limited by a lack of understanding of the intra- and intercellular mechanisms associated with the activation of innate immune receptors and their impact on adaptive tubular repair. Accumulating evidence suggests that TEC-associated innate immunity shapes the tubular response to stress through the regulation of immunometabolism. Engagement of innate immune receptors provides TECs with the metabolic flexibility necessary for their plasticity during injury and repair. This could significantly affect pathogenic processes within TECs, such as cell death, mitochondrial damage, senescence, and pro-fibrotic cytokine secretion, well-known to exacerbate inflammation and fibrosis. This article provides an overview of the past 5 years of research on the role of innate immunity in experimental and human IRI, with a focus on the cascade of events activated by hypoxic damage in TECs: from programmed cell death (PCD) and mitochondrial dysfunction-mediated metabolic rewiring of TECs to maladaptive repair and progression to fibrosis. Finally, we will discuss the important crosstalk between metabolism and innate immunity observed in TECs and their therapeutic potential in both experimental and clinical research.

Frailty in Critical Care Medicine: A Review

Traditional approaches to clinical risk assessment utilize age as a marker of increased vulnerability to stress. Relatively recent advancements in the study of aging have led to the concept of the frailty syndrome, which represents a multidimensional state of depleted physiologic and psychosocial reserve and clinical vulnerability that is related to but variably present with advancing age. The frailty syndrome is now a well-established clinical entity that serves as both a guide for clinical intervention and a predictor of poor outcomes in the primary and acute care settings. The biological aspects of the syndrome broadly represent a network of interrelated perturbations involving the age-related accumulation of molecular, cellular, and tissue damage that leads to multisystem dysregulation, functional decline, and disproportionately poor response to physiologic stress. Given the complexity of the underlying biologic processes, several well-validated approaches to define frailty clinically have been developed, each with distinct and reasonable considerations. Stemming from this background, the past several years have seen a number of observational studies conducted in intensive care units that have established that the determination of frailty is both feasible and prognostically useful in the critical care setting. Specifically, frailty as determined by several different frailty measurement tools appears associated with mortality, increased health care utilization, and disability, and has the potential to improve risk stratification of intensive care patients. While substantial variability in the implementation of frailty measurement likely limits the generalizability of specific findings, the overall prognostic trends may offer some assistance in guiding management decisions with patients and their families. Although no trials have assessed interventions to improve the outcomes of critically ill older people living with frailty, the particular vulnerability of this population offers a promising target for intervention in the future.

miR-214 represses mitofusin-2 to promote renal tubular apoptosis in ischemic acute kidney injury

Disruption of mitochondrial dynamics is an important pathogenic event in both acute and chronic kidney diseases, but the underlying mechanism remains poorly understood. Here, we report the regulation of mitofusin-2 (Mfn2; a key mitochondrial fusion protein) by microRNA-214 (miR-214) in renal ischemia-reperfusion that contributes to mitochondrial fragmentation, renal tubular cell death, and ischemic acute kidney injury (AKI). miR-214 was induced, whereas Mfn2 expression was decreased, in mouse ischemic AKI and cultured rat kidney proximal tubular cells (RPTCs) following ATP depletion treatment. Overexpression of miR-214 decreased Mfn2. Conversely, inhibition of miR-214 with anti-miR-214 prevented Mfn2 downregulation in RPTCs following ATP depletion. Anti-miR-214 further ameliorated mitochondrial fragmentation and apoptosis, whereas overexpression of miR-214 increased apoptosis, in ATP-depleted RPTCs. To test regulation in vivo, we established a mouse model with miR-214 specifically deleted from kidney proximal tubular cells (PT-miR-214-/-). Compared with wild-type mice, PT-miR-214-/- mice had less severe tissue damage, fewer apoptotic cells, and better renal function after ischemic AKI. miR-214 induction in ischemic AKI was suppressed in PT-miR-214-/- mice, accompanied by partial preservation of Mfn2 in kidneys. These results unveil the miR-214/Mfn2 axis that contributes to the disruption of mitochondrial dynamics and tubular cell death in ischemic AKI, offering new therapeutic targets.

Sex differences in redox homeostasis in renal disease

Sex differences in redox signaling in the kidney present new challenges and opportunities for understanding the physiology and pathophysiology of the kidney. This review will focus on reactive oxygen species, immune-related signaling pathways and endothelin-1 as potential mediators of sex-differences in redox homeostasis in the kidney. Additionally, this review will highlight male-female differences in redox signaling in several major cardiovascular and renal disorders namely acute kidney injury, diabetic nephropathy, kidney stone disease and salt-sensitive hypertension. Furthermore, we will discuss the contribution of redox signaling in the pathogenesis of postmenopausal hypertension and preeclampsia.