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 in humans, some authorities assert that female sex 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.

SETTINGS & PARTICIPANTS

All patients hospitalized in the Montefiore Health System between 10/15/2015 and 1/1/2019, excluding those with kidney failure or obstetrics diagnoses.

EXPOSURE

Male versus female sex.

OUTCOMES

Acute kidney injury (AKI) occurring during hospitalization based on KDIGO definitions.

ANALYTICAL APPROACH

Generalized Estimating Equation logistic regression adjusted for comorbidities, socio-demographic factors, and severity of illness. Analyses were stratified into 3 age categories, 6 months to ≤16 years, age >16 years - <55 years, and age ≥55 years.

RESULTS

A total of 132,667 individuals were hospitalized a total of 235,629 times. The mean age was 55.2 (SD 23.8) years. The counts (%) of hospitalizations for women were 129,912 (55%). Hospitalization counts (%) among Black and Hispanic patients were 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 higher risk of AKI across all age groups, an association more pronounced in the age group >16 years to <55 years in which the OR 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.

CONCLUSION

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

Sex as a biological variable in acute kidney injury

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of the preclinical and clinical studies investigating sex as a biological variable, as well as the impact of gender, on the development of and progression of acute kidney injury (AKI).

RECENT FINDINGS

Despite a matched degree of ischemia-reperfusion AKI based on measured glomerular filtration rates, male and female mice demonstrated important sex biases in cardiorenal outcomes (1). Although the 2012 Kidney Disease Improving Global Outcomes (KDIGO) Clinical Practice Guideline for AKI reported that female sex is associated with increased rates of hospital acquired AKI, subsequent meta-analyses do not show increased risk of AKI in women. Recent large scale, multicenter epidemiologic studies suggest males have higher rates of hospital acquired AKI. However, women have been consistently shown to have worse renal outcomes after AKI. There may be also be gender-based differences in presentation to care and management.

SUMMARY

Sex is an important biological variable in animal models of acute kidney injury. The impact of sex on AKI likely varies based on the etiology of AKI. Preclinical studies demonstrate the nuances of sex chromosomes, sex hormones and epigenetic factors on AKI, however these have not been well studied in humans. Gender may also impact processes of care, treatment and clinical outcomes related to AKI. The scientific rigor and reproducibility of translational studies benefit from the consideration of sex and gender.

Predicting the risk of acute kidney injury after cardiopulmonary bypass: development and assessment of a new predictive nomogram

BACKGROUND

Acute kidney injury (AKI) is a common and severe complication of cardiac surgery with cardiopulmonary bypass (CPB). This study aimed to establish a model to predict the probability of postoperative AKI in patients undergoing cardiac surgery with CPB.

METHODS

We conducted a retrospective, multicenter study to analyze 1082 patients undergoing cardiac surgery under CPB. The least absolute shrinkage and selection operator regression model was used to optimize feature selection for the AKI model. Multivariable logistic regression analysis was applied to build a prediction model incorporating the feature selected in the previously mentioned model. Finally, we used multiple methods to evaluate the accuracy and clinical applicability of the model.

RESULTS

Age, gender, hypertension, CPB duration, intraoperative 5% bicarbonate solution and red blood cell transfusion, urine volume were identified as important factors. Then, these risk factors were created into nomogram to predict the incidence of AKI after cardiac surgery under CPB.

CONCLUSION

We developed a nomogram to predict the incidence of AKI after cardiac surgery. This model can be used as a reference tool for evaluating early medical intervention to prevent postoperative AKI.

Polymyxin B-Associated Nephrotoxicity and Its Predictors: A Retrospective Study in Carbapenem-Resistant Gram-Negative Bacterial Infections

Polymyxin B (PMB), a kind of polymyxin, was widely used in carbapenem-resistant Gram-negative bacterial (CR-GNB) infections. However, adverse reactions such as nephrotoxicity and neurotoxicity limit its use in clinical practice. The aim of this study was to explore PMB associated with nephrotoxicity and its predictors. Patients who received PMB intravenous drip for more than 72 h were eligible for the study. Characteristics of patients, concomitant nephrotoxic agents, underlying disease, and antimicrobial susceptibility were submitted for descriptive analysis. Univariate analysis and binary logistic regression were used to assess the factors leading to acute kidney injury (AKI). AKI was assessed with serum creatinine variations according to the classification of risk (stage R), injury (stage I), failure (stage F), loss, and end-stage of kidney disease. Among 234 patients with CR-GNB infections who used PMB in our study, 67 (28.63%) patients developed AKI, including 31 (14.25%) patients in stage R, 15 (6.41%) patients in stage I, and 21 (8.97%) patients in stage F. The incident rate of PMB-related nephrotoxicity in patients with normal renal function was 32.82% (43/131). The higher risk factors of AKI include males [odds ratio (OR) = 3.237; 95% confidence interval (95%CI) = 1.426–7.350], digestive system diseases [OR = 2.481 (1.127–5.463)], using furosemide (&gt;20 mg/day) [OR = 2.473 (1.102–5.551)], and baseline serum creatinine [OR = 0.994 (0.990–0.999)]. Nonparametric tests of K-independent samples showed that baseline serum creatinine and the PMB maintenance dose were associated with the severity of nephrotoxicity (both p &lt; 0.05). Male, digestive system diseases, using furosemide (&gt;20 mg/day), and high baseline serum creatinine were the independent risk factors of PMB-associated AKI development. The maintenance dose of PMB may be related to the severity of AKI. These risk factors should be taken into consideration when initiating PMB-based therapy. The serum creatinine value should be closely monitored when using PMB.

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.

The influence of renal ischemia-reperfusion injury on remote organs: The histological brain changes in male and female rats

INTRODUCTION:

Brain tissue was adversely affected by renal ischemia-reperfusion injury (renal IRI) in several studies. Moreover, we are awareness that kidney diseases are gender dependent, but there is not enough evidence of the impact of gender on renal IRI-induced brain injury. Hence, this study was designed to investigate gender differences in renal IRI-induced brain tissue injury in adult rats.

MATERIALS AND METHODS:

Forty Wistar rats (four groups) include two main groups (20 male and 20 female). Each of them was divided into two subgroups including 1 and 2: male and female sham-operated groups and 3and 4: male and female ischemia (ISC) groups were exposed to renal ischemia for 45 min and then 24 h reperfusion (male and female ISC 24 h). Sham groups were exposed to surgery without ischemia process. After reperfusion time, blood samples were obtained for the renal function measurements. The kidney and brain were removed and were fixed in a 10% formalin solution for pathological assessment. The left kidney was used to measure malondialdehyde (MDA) and nitrite.

RESULTS:

Renal IRI increased significantly levels of creatinine, blood urea nitrogen, kidney weight, and damage score in both genders (P < 0.05). Furthermore, brain injuries were significantly higher following 24 h of reperfusion in male and female groups. Serum nitrite level and MDA concentration of female rats decreased significantly in ISC 24 h group (P < 0.05) but not in male rats.

CONCLUSION:

The brain tissue of both genders, male and female, is affected by renal IRI as a remote organ. Female sex hormones may indicate a protective role against IR by the nitric oxide pathway and antioxidant signaling.

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

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

Mas receptor antagonist (A799) alters the renal hemodynamics responses to angiotensin II administration after renal moderate ischemia/reperfusion in rats: gender related differences

Moderate renal ischemia/reperfusion (I/R) injury is one of the major causes of kidney failure. We examined the role of Mas receptor (MasR) antagonist (A779) alone and combined with angiotensin II (Ang II) type 2 receptor (AT2R) antagonist (PD123319) on renal hemodynamic responses to Ang II after moderate I/R in male and female rats. Anaesthetized Wistar rats underwent 30 min partial ischemia by reduction of renal perfusion pressure (RPP) and subjected to block vasodepressor receptors followed by Ang II (100 and 300 ng/kg/min) infusion. Mean arterial pressure (MAP), renal blood flow (RBF), and renal vascular resistance (RVR) responses were assessed during graded Ang II infusion at controlled RPP. Thirty min post reperfusion, the Ang II infusion reduced RBF and increased RVR in a dose-related fashion (P < 0.05). However, A779 alone or A779 plus PD123319 infusion increased the RBF and RVR responses to Ang II infusion significantly (P < 0.05) in female but not in the male rats. MasR antagonist altered the RBF and RVR responses to Ang II infusion in female, and these responses were not altered statistically in dual blockade of MasR and AT2R. These findings suggest the important role of Mas receptor in renal vascular response to Ang II in female rats after moderate I/R.

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

Background

Female sex has been included as a risk factor in models developed to predict the development of AKI. In addition, the commentary to the Kidney Disease Improving Global Outcomes Clinical Practice Guideline for AKI concludes that female sex is a risk factor for hospital-acquired AKI. In contrast, a protective effect of female sex has been demonstrated in animal models of ischemic AKI.

Methods

To further explore this issue, we performed a meta-analysis of AKI studies published between January, 1978 and April, 2018 and identified 83 studies reporting sex-stratified data on the incidence of hospital-associated AKI among nearly 240,000,000 patients.

Results

Twenty-eight studies (6,758,124 patients) utilized multivariate analysis to assess risk factors for hospital-associated AKI and provided sex-stratified ORs. Meta-analysis of this cohort showed that the risk of developing hospital-associated AKI was significantly greater in men than in women (OR 1.23 (1.11,1.36). Since AKI is not a single disease but instead represents a heterogeneous group of disorders characterized by an acute reduction in renal function, we performed subgroup meta-analyses. The association of male sex with AKI was strongest among studies of patients who underwent non-cardiac surgery. Male sex was also associated with AKI in studies which included unselected hospitalized patients and in studies of critically ill patients who received care in an intensive care unit. In contrast, cardiac surgery-associated AKI and radiocontrast-induced AKI showed no sexual dimorphism.

Conclusions

Our meta-analysis contradicts the established belief that female sex confers a greater risk of AKI and instead suggests a protective role.

Sex differences in acute kidney injury requiring dialysis

Background

Female sex has been included as a risk factor in models developed to predict the risk of acute kidney injury (AKI) associated with cardiac surgery, aminoglycoside nephrotoxicity and contrast-induced nephropathy. The commentary acompanying the Kidney Disease Improving Global Outcomes Clinical Practice Guideline for Acute Kidney Injury concludes that female sex is a shared susceptibility factor for acute kidney injury based on observations that female sex is associated with the development of hospital-acquired acute kidney injury. In contrast, female sex is reno-protective in animal models. In this context, we sought to examine the role of sex in hospital-associated acute kidney injury in greater detail.

Methods

We utilized the Hospital Episode Statistics database to calculate the sex-stratified incidence of AKI requiring renal replacement therapy (AKI-D) among 194,157,726 hospital discharges reported for the years 1998–2013. In addition, we conducted a systematic review of the English literature to evaluate dialysis practices among men versus women with AKI.

Results

Hospitalized men were more likely to develop AKI-D than hospitalized women (OR 2.19 (2.15, 2.22) p < 0.0001). We found no evidence in the published literature that dialysis practices differ between men and women with AKI.

Conclusions

Based on a population of hospitalized patients which is more than 3 times larger than all previously published cohorts reporting sex-stratified AKI data combined, we conclude that male sex is associated with an increased incidence of hospital-associated AKI-D. Our study is among the first reports to highlight the protective role of female gender in AKI.

Postnatal high-fat diet sex-specifically exacerbates prenatal dexamethasone-induced hypertension: Mass spectrometry-based quantitative proteomic approach

Hypertension can originate from pre- and post-natal insults. High-fat (HF) diet and prenatal dexamethasone (DEX) exposure are both involved in hypertension of developmental origins. We examined whether postnatal HF diet sex-specifically increases the vulnerability to prenatal DEX exposure-induced programmed hypertension in adult offspring. Additionally, we sought to identify candidate proteins involved in programmed hypertension through a mass spectrometry-based quantitative proteomic approach. Male and female offspring were studied separately: control, DEX, HF, and DEX + HF (n=8/group). Pregnant Sprague-Dawley rats received dexamethasone (0.1 mg/kg body weight) or vesicle from gestational day 16-22. Offspring received high-fat diet (D12331, Research Diets) or regular diet from weaning to 4 months of age. Rats were sacrificed at 4 months of age. We found that postnatal HF diet increased vulnerability of prenatal DEX-induced hypertension in male but not in female adult offspring. Additionally, HF and DEX elicited renal programming in a sex-specific fashion. In males, DEX + HF increased renal parvalbumin (PVALB) and carbonic anhydrase III (CA III) protein levels. While prenatal DEX down-regulated PVALB and CA III protein abundance in female offspring kidneys. Moreover, DEX + HF increased renal protein level of type 3 sodium hydrogen exchanger (NHE3) in males but not in females. In conclusion, postnatal HF diet and prenatal DEX exposure synergistically induced programmed hypertension in male-only offspring. DEX + HF induced sex-specific alterations of protein profiles in offspring kidneys. By identifying candidate proteins underlying sex-specific mechanisms, our results could lead to novel offspring sex-specific interventions to prevent hypertension induced by antenatal corticosteroids and postnatal HF intake in both sexes.

Gender proteomics I. Which proteins in non-sexual organs

Differences related to gender have long been neglected but recent investigations show that they are widespread and may be recognized with all types of omics approaches, both in tissues and in biological fluids. Our review compiles evidence collected with proteomics techniques in our species, mainly focusing on baseline parameters in non-sexual organs in healthy men and women. Data from human specimens had to be replaced with information from other mammals every time invasive procedures of sample procurement were involved.

SIGNIFICANCE

As our knowledge, and the methods to build it, get refined, gender differences need to receive more and more attention, as they influence the outcome of all aspects in lifestyle, including diet, exercise and environmental factors. In turn this background modulates a differential susceptibility to some disease, or a different pathogenetic mechanism, depending on gender, and a different response to pharmacological therapy. Preparing this review we meant to raise awareness about the gender issue. We anticipate that more and more often, in the future, separate evaluations will be carried out on male and female subjects as an alternative - and an upgrade - to the current approach of reference and test groups being 'matched for age and sex'.

Vasa recta pericyte density is negatively associated with vascular congestion in the renal medulla following ischemia reperfusion in rats

Recent evidence suggests that a greater density of pericytes in renal cadaveric allografts is associated with better recovery following transplant. The physiological mechanism(s) through which pericyte density may be beneficial is not well understood. The goal of this study was to test the hypothesis that lower medullary pericyte density is associated with greater renal injury following ischemia reperfusion (IR) in a rat model, providing a basis for future studies to better understand pericytes in a pathological environment. To test our hypothesis, we determined the association between medullary pericyte density and renal injury in spontaneously hypertensive rats (SHR) following 45 min of warm bilateral IR. We found that there was a significant negative relationship between pericyte density and plasma creatinine (slope = -0.03, P = 0.02) and blood urea nitrogen (slope = -0.5, P = 0.01) in female but not male SHR. Pericyte density was negatively associated with medullary peritubular capillary (PT) congestion in both sexes following IR (male: slope = -0.04, P = 0.009; female: slope = -0.03, P = 0.0001). To further test this relationship, we used a previously reported method to reduce pericyte density in SHR. Medullary erythrocyte congestion in vasa recta (VR) and PT significantly increased following IR in both sexes when pericyte density was pharmacologically decreased (VR: P = 0.03; PT: P = 0.03). Our data support the hypothesis that pericyte density is negatively associated with the development of IR injury in SHR, which may be mediated by erythrocyte congestion in the medullary vasculature.

Gender Difference in Renal Blood Flow Response to Angiotensin II Administration after Ischemia/Reperfusion in Rats: The Role of AT2 Receptor

Background. Renal ischemia/reperfusion (I/R) is one of the major causes of kidney failure, and it may interact with renin angiotensin system while angiotensin II (Ang II) type 2 receptor (AT2R) expression is gender dependent. We examined the role of AT2R blockade on vascular response to Ang II after I/R in rats. Methods. Male and female rats were subjected to 30 min renal ischemia followed by reperfusion. Two groups of rats received either vehicle or AT2R antagonist, PD123319. Mean arterial pressure (MAP), and renal blood flow (RBF) responses were assessed during graded Ang II (100, 300, and 1000 ng/kg/min, i.v.) infusion at controlled renal perfusion pressure (RPP). Results. Vehicle or antagonist did not alter MAP, RPP, and RBF levels significantly; however, 30 min after reperfusion, RBF decreased insignificantly in female treated with PD123319 (P = 0.07). Ang II reduced RBF and increased renal vascular resistance (RVR) in a dose-related fashion (P dose < 0.0001), and PD123319 intensified the reduction of RBF response in female (P group < 0.005), but not in male rats. Conclusion. The impact of the AT2R on vascular responses to Ang II in renal I/R injury appears to be sexually dimorphic. PD123319 infusion promotes these hemodynamic responses in female more than in male rats.

How has urinary proteomics contributed to the discovery of early biomarkers of acute kidney injury?

In the past decade, analysis of the urinary proteome (urinary proteomics) has intensified in response to the need for novel biomarkers that support early diagnosis of kidney diseases. In particular, this also applies to acute kidney injury, which is a heterogeneous complex syndrome with a still-increasing incidence at the intensive care unit. Unfortunately, this major need remains largely unmet to date. The current report aims to explain why attempts to implement urinary proteomic-discovered acute kidney injury diagnostic candidates in the intensive care unit setting have not yet led to success. Subsequently, some key notes are provided that should enhance the chance of translating selected urinary proteomic candidates to valuable tools for the nephrologist and intensivist in the near future.

The effects of alpha-lipoic acid on MMP-2 and MMP-9 activities in a rat renal ischemia and re-perfusion model

Matrix metalloproteinases (MMPs) are enzymes that are responsible for degradation of extracellular matrix (ECM); they are involved in the pathogenesis of ischemia-re-perfusion (I-R) injury. We investigated the possible preventive effect of alpha-lipoic acid (LA) in a renal I-R injury model in rats by assessing its reducing effect on the expression and activation of MMP-2 and MMP-9 induced by I-R. Rats were assigned to four groups: control, sham-operated, I-R (saline, i.p.) and I-R+ LA (100 mg/kg, i.p.). After a right nephrectomy, I-R was induced by clamping the left renal pedicle for 1 h, followed by 6 h re-perfusion. In the sham group, a right nephrectomy was performed and left renal pedicles were dissected without clamping and the entire left kidney was excised after 6 h. LA pretreatment was started 30 min prior to induction of ischemia. Injury to tubules was evaluated using light and electron microscopy. The expressions of MMP-2 and MMP-9 were determined by immunohistochemistry and their activities were analyzed by gelatin zymography. Serum creatinine was measured using a quantitative kit based on the Jaffe colorimetric technique. Malondialdehyde (MDA) and glutathione (GSH) were analyzed using high performance liquid chromatography. Tissue inhibitor of metalloproteinase (TIMP)-2 and TIMP-1 were assessed using enzyme-linked immunosorbent assay (ELISA). I-R caused tubular dilatation and brush border loss. LA decreased both renal dysfunction and abnormal levels of MDA and GSH during I-R. Moreover, LA decreased significantly both MMP-2 and MMP-9 expressions and activations during I-R. TIMP-1 and TIMP-2 levels were increased significantly by LA administration. LA modulated increased MMP-2 and MMP-9 activities and decreased TIMP-1 and TIMP-2 levels during renal I-R.

Oligomycin, an F1Fo-ATPase inhibitor, protects against ischemic acute kidney injury in male but not in female rats

We investigated the effects of oligomycin, an F1Fo-ATPase inhibitor, on ischemic acute kidney injury in male and female rats. Ischemic acute kidney injury was induced by clamping the left renal artery and vein for 45 or 60 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal dysfunction and histological renal damage were observed 1 day after reperfusion in both male and female rats, although these renal injuries were more marked in male rats than in female rats. Intravenous bolus injection of oligomycin (0.5 mg/kg) 5 min before ischemia markedly attenuated the ischemia/reperfusion-induced renal injury in male rats. However, oligomycin did not show the protective effect in female rats subjected to ischemia/reperfusion-induced renal injury. Pre-ischemic treatment with oligomycin suppressed partly but significantly ischemia-induced renal ATP depletion only in male rats. These results indicate that oligomycin prevents the onset of ischemic acute kidney injury in male but not in female rats, and the effect is accompanied by suppression of the ATP depletion only in the male rat kidney during ischemia, thereby suggesting that the ATP hydrolysis pathway by mitochondrial F1Fo-ATPase induces a sex difference in ischemic acute kidney injury.

Molecular pathology of acute kidney injury in a choline-deficient model and fish oil protective effect

PURPOSE

The aim of this work was to investigate the potential protective effects of fish oil on the basis of kidney transcriptomic data on a nutritional experimental model.

METHODS

Male weanling Wistar rats were divided into four groups and fed choline-deficient (CD) and choline-supplemented (CS) diets with vegetable oil (VO) and menhaden oil (MO): CSVO, CDVO, CSMO and CDMO. Animals were killed after receiving the diets for 6 days. Total RNA was purified from the right kidney and hybridized to Affymetrix GeneChip Rat Gene 1.0 ST Array. Differentially expressed genes were analyzed.

RESULTS

All CSVO, CSMO and CDMO rats showed no renal alterations, while all CDVO rats showed renal cortical necrosis. A thorough analysis of the differential expression between groups CSMO and CDMO was carried out. There were no differential genes for p < 0.01. The analysis of the differential expression between groups CSVO and CSMO revealed 32 genes, 11 were over-expressed and 21 were under-expressed in CSMO rats.

CONCLUSIONS

This work was part of a large set of experiments and was used in a hypothesis-generating manner. The comprehensive analysis of genetic expression allowed confirming that menhaden oil has a protective effect on this nutritional experimental model and identifying 32 genes that could be responsible for that protection, including Gstp1. These results reveal that gene changes could play a role in renal injury.

Gender difference in Cisplatin-induced nephrotoxicity in a rat model: greater intensity of damage in male than female

Background

Nephrotoxicity and hepatotoxicity are side effects of Cisplatin (CP) therapy.

Objectives

We investigated the role of gender in CP-induced nephrotoxicity and hepatotoxicity.

Materials and Methods

Low dose of CP (1 mg/kg/day; ip) was administered daily to male and female Wistar rats for 15 consecutive days. Serum creatinine (Cr), blood urea nitrogen (BUN), malondialdehyde (MDA), nitric oxide (NO) metabolite, and magnesium (Mg) levels were determined.

Results

The percentage of weight loss and the serum levels of MDA and nitrite in male and female animals were not statistically different. However, the serum levels of BUN, Cr, Mg, and kidney MDA levels, and kidney weight and damage score were significantly greater in males than in females (P < 0.05).

Conclusions

CP-induced nephrotoxicity is gender related for which the mechanisms should be determined.

Gender difference and sex hormone production in rodent renal ischemia reperfusion injury and repair

BACKGROUND

Several lines of evidence suggest a protective effect of female sex hormones in several organs subjected to ischemia-reperfusion injury. The aim of the study was to investigate sex hormone production in male rats after a renal ischemia-reperfusion sequence and analyze the influence of gender differences on tissue remodelling during the recovery process.

METHOD

Age-matched sexually mature male and female rats were subjected to 60 min of renal unilateral ischemia by pedicle clamping with contralateral nephrectomy and followed for 1 or 5 days after reperfusion. Plasma creatinine, systemic testosterone, progesterone and estradiol levels were determined. Tubular injury, cell proliferation and inflammation, were evaluated as well as proliferating cell nuclear antigen, vimentin and translocator protein (TSPO) expressions by immunohistochemistry.

RESULTS

After 1 and 5 days of reperfusion, plasma creatinine was significantly higher in males than in females, supporting the high mortality in this group. After reperfusion, plasma testosterone levels decreased whereas estradiol significantly increased in male rats. Alterations of renal function, associated with tubular injury and inflammation persisted during the 5 days post-ischemia-reperfusion, and a significant improvement was observed in females at 5 days of reperfusion. Proliferating cell nuclear antigen and vimentin expression were upregulated in kidneys from males and attenuated in females, in parallel to injury development. TSPO expression was transiently increased in proximal tubules in male rats.

CONCLUSIONS

After ischemia, renal function recovery and tissue injury is gender-dependent. These differences are associated with a modulation of sex hormone production and a modification of tissue remodeling and proliferative cell processes.

Activation of the epidermal growth factor receptor (EGFR) by a novel metalloprotease pathway

Neutrophil Elastase (NE) is a pro-inflammatory protease present at higher than normal levels in the lung during inflammatory disease. NE regulates IL-8 production from airway epithelial cells and can activate both EGFR and TLR4. TACE/ADAM17 has been reported to trans-activate EGFR in response to NE. Here, using 16HBE14o-human bronchial epithelial cells we demonstrate a new mechanism by which NE regulates both of these events. A high molecular weight soluble metalloprotease activity detectable only in supernatants from NE-treated cells by gelatin and casein zymography was confirmed to be meprin alpha by Western immunoblotting. In vitro studies demonstrated the ability of NE to activate meprin alpha, which in turn could release soluble TGFalpha and induce IL-8 production from 16HBE14o- cells. These effects were abrogated by actinonin, a specific meprin inhibitor. NE-induced IL-8 expression was also inhibited by meprin alpha siRNA. Immunoprecipitation studies detected EGFR/TLR4 complexes in NE-stimulated cells overexpressing these receptors. Confocal studies confirmed colocalization of EGFR and TLR4 in 16HBE14o- cells stimulated with meprin alpha. NFkappaB was also activated via MyD88 in these cells by meprin alpha. In bronchoalveolar lavage fluid from NE knock-out mice infected intra-tracheally with Pseudomonas aeruginosa meprin alpha was significantly decreased compared with control mice, and was significantly increased and correlated with NE activity, in bronchoalveolar lavage fluid from individuals with cystic fibrosis but not healthy controls. The data describe a previously unidentified lung metalloprotease meprin alpha, and its role in NE-induced EGFR and TLR4 activation and IL-8 production.