Estrogen Protects against Oxidative Multiorgan Damage in Rats with Chronic Renal Failure

Role of Sex Hormones in Prevalent Kidney Diseases

Chronic kidney disease (CKD) is a constantly growing global health burden, with more than 840 million people affected worldwide. CKD presents sex disparities in the pathophysiology of the disease, as well as in the epidemiology, clinical manifestations, and disease progression. Overall, while CKD is more frequent in females, males have a higher risk to progress to end-stage kidney disease. In recent years, numerous studies have highlighted the role of sex hormones in the health and diseases of several organs, including the kidney. In this review, we present a clinical overview of the sex-differences in CKD and a selection of prominent kidney diseases causing CKD: lupus nephritis, diabetic kidney disease, IgA nephropathy, and autosomal dominant polycystic kidney disease. We report clinical and experimental findings on the role of sex hormones in the development of the disease and its progression to end-stage kidney disease.

The Clinical Impact of Platelets on Post-Injury Serum Creatinine Concentration in Multiple Trauma Patients: A Retrospective Cohort Study

Background and objective: Platelets contribute to the immunological response after multiple trauma. To determine the clinical impact, this study analyzes the association between platelets and creatinine concentration as an indicator of kidney function in polytraumatized patients. Methods: We investigated all patients presenting an Injury Severity Score (ISS) ≥16 for a 2-year period at our trauma center. Platelet counts and creatinine concentrations were analyzed, and correlation analysis was performed within 10 days after multiple trauma. Results: 83 patients with a median ISS of 22 were included. Platelet count was decreased on day 3 (p ≤ 0.001) and increased on day 10 (p ≤ 0.001). Platelet count was elevated on day 10 in younger patients and diminished in severely injured patients (ISS ≥35) on day 1 (p = 0.012) and day 3 (p = 0.011). Creatinine concentration was decreased on day 1 (p = 0.003) and day 10 (p ≤ 0.001) in female patients. Age (p = 0.01), male sex (p = 0.004), and injury severity (p = 0.014) were identified as factors for increased creatinine concentration on day 1, whereas platelets (p = 0.046) were associated with decreased creatinine concentrations on day 5 after multiple trauma. Conclusions: Kinetics of platelet count and creatinine concentration are influenced by age, gender, and trauma severity. There was no clear correlation between platelet counts and creatinine concentration. However, platelets seem to have a modulating effect on creatinine concentrations in the vulnerable phase after trauma.

Estrogens and phytoestrogens in body functions

Estrogens are the hormones of reproduction in women as well as of many other important functions in the male and female body. They undergo significant changes in the different phases of life, e.g. during puberty, pregnancy or at menopause/andropause. Phytoestrogens are natural non-steroidal phenolic plant compounds that can mimic the activity of estrogens and their beneficial effects in women and in men. This narrative review summarizes the literature on the physiological role of estrogens and the several potential health benefits of phytoestrogens, with particular attention given to the possible role of phytoestrogens in aging.

Effects of excessive sodium chloride loading in the spontaneously diabetic torii (SDT) fatty rats, a preclinical model of type 2 diabetes mellitus

Type 2 diabetes mellitus represents an international health concern with its growing number of patients worldwide. At the same time, excessive salt consumption is also seen as a major cause of diseases such as hypertension and may expedite renal complications in diabetic patients. In this study, we investigated the effects of excessive sodium chloride supplementation on the kidney of the Spontaneously Diabetic Torii-Lepr^fa (SDT fatty) rat, an obese type 2 diabetes model. Male and female SDT fatty rats and normal Sprague-Dawley (SD) rats at 5 weeks of age were loaded with 0.3% sodium chloride (NaCl) in drinking water for 13 weeks. Blood serum and urinary parameters were observed throughout the experiment and kidney samples were examined in histopathological and genetical analyses. Significant changes on the body weight, blood pressure, urine volume, creatinine clearance, blood urea nitrogen (BUN), relative gene expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), monocyte chemotactic protein-1 (MCP-1) and transforming growth factor-β (TGF-β) were observed in the salt-loaded male SDT fatty rats. Urinary L-type fatty acid-binding protein (L-FABP) and albumin levels were higher observed in the salt-loaded male SDT fatty rats throughout the period, but urinary albumin levels in the female SDT fatty rats remain unchanged. In the kidney, slight Armani-Ebstein changes, tubular degeneration, hyaline cast, and inflammatory cell infiltration were observed in female SDT fatty rats while the levels of some changes were higher in the salt-loaded group. The kidney of the salt-loaded male SDT fatty rats demonstrated a higher degree of lesions compared to the female group and the male unloaded group. Histopathological changes in salt-loaded SDT fatty rats show that excessive salt consumption may act as a diabetic pathology exacerbation factor, but the pathology may be influenced by gender difference. Urinary L-FABP levels may act as a useful biomarker to detect slight tubular damages in the kidney. Excessive salt loading was shown to exacerbate the renal injury in SDT fatty rats.

A high dose of estrogen can improve renal ischemia-reperfusion-induced pulmonary injury in ovariectomized female rats

Renal ischemia-reperfusion injury (RIRI) as a pathological process induces remote organ injury such as lung complications and it is regulated in a hormone-dependent manner. This study investigates the effect of estrogen on RIR-induced pulmonary injury in ovariectomized (OV) rats. A total of 60 female Wistar rats were divided into six groups: (i) intact sham, (ii) OV sham, (iii) OV sham + estradiol valerate (E), (iv) intact ischemia, (v) OV ischemia, and (vi) OV ischemia + E. Bilateral ischemia was performed for 45 min in all groups except sham. Before the ischemia, OV groups received an intramuscular (i.m.) injection of E. After reperfusion, blood samples were collected for serum analysis and kidney and lung tissue were separated for pathological experiment and malondialdehyde (MDA) and nitrite measurement. The left lung was weighed to measure pulmonary edema. Estrogen deficiency caused a greater increase in blood urea nitrogen and creatinine levels during IRI. Ischemia reduced nitrite of serum and lung tissue. The increased level of MDA during ischemia, returned to normal levels via estrogen injection. The severity of renal and lung damage in ischemic groups increased significantly, and estrogen improved this injury. Estrogen as an antioxidant agent can reduce oxidative stress and may improve renal function and ameliorating lung damage caused by RIR.

Development of a murine iliac arteriovenous fistula model for examination of hemodialysis access-related limb pathophysiology

OBJECTIVE

Hemodialysis access-related hand dysfunction is a common clinical feature of patients with chronic kidney disease (CKD) after arteriovenous fistula (AVF) placement. The heterogeneity in symptoms and the lack of a predictive association with changes in hemodynamic alterations precipitated by the AVF suggest that other factors are involved in the mechanisms responsible for causing hand and limb dysfunction postoperatively. To the best of our knowledge, no suitable animal models have provided a platform for performing preclinical experiments designed to elucidate the biologic drivers of access-related hand dysfunction. Therefore, our objective was to develop a novel murine AVF model that could be used to study dialysis access-related limb dysfunction.

METHODS

Male 8-week-old C57BL/6J mice (n = 15/group) were exposed to either an adenine-supplemented diet to induce CKD or casein-based chow (control). Four weeks after the diet intervention, the mice were randomly assigned to receive an iliac AVF (n = 10/group) or sham surgery (n = 5/group) on the left hindlimb. The mice were sacrificed 2 weeks after surgery, and AVF specimens and hindlimb skeletal muscles were collected for further analysis.

RESULTS

Before AVF or sham surgery, the glomerular filtration rates were significantly reduced and the blood urea nitrogen levels were significantly elevated in the CKD groups compared with the controls (P < .05). AVF surgery was associated with an ∼80% patency rate among the survivors (four control and three CKD mice died postoperatively). Patency was verified by changes in hemodynamics using Doppler ultrasound imaging and altered histologic morphology. Compared with sham surgery, AVF surgery reduced ipsilateral hindlimb perfusion to the tibialis anterior muscle (20%-40%) and paw (40%-50%), which remained stable until euthanasia. Analysis of gastrocnemius muscle mitochondrial respiratory function uncovered a significant decrease (40%-50%) in mitochondrial function in the AVF mice. No changes were found in the muscle mass, myofiber cross-sectional area, or centrally nucleated fiber proportion in the extensor digitorum longus and soleus muscles between the sham and AVF mice.

CONCLUSIONS

The results from the present study have demonstrated that iliac AVF formation is a practical animal model that facilitates examination of hemodialysis access-related limb dysfunction. AVF surgery produced the expected hemodynamic changes, and evaluation of the limb muscle revealed a substantial mitochondrial impairment that was present without changes in muscle size.

Ischemic preconditioning protects the heart against ischemia-reperfusion injury in chronic kidney disease in both males and females

BACKGROUND

Uremic cardiomyopathy is a common cardiovascular complication of chronic kidney disease (CKD) characterized by left ventricular hypertrophy (LVH) and fibrosis enhancing the susceptibility of the heart to acute myocardial infarction. In the early stages of CKD, approximately 60% of patients are women. We aimed to investigate the influence of sex on the severity of uremic cardiomyopathy and the infarct size-limiting effect of ischemic preconditioning (IPRE) in experimental CKD.

METHODS

CKD was induced by 5/6 nephrectomy in 9-week-old male and female Wistar rats. Two months later, serum and urine laboratory parameters were measured to verify the development of CKD. Transthoracic echocardiography was performed to assess cardiac function and morphology. Cardiomyocyte hypertrophy and fibrosis were measured by histology. Left ventricular expression of A- and B-type natriuretic peptides (ANP and BNP) were measured by qRT-PCR and circulating BNP level was measured by ELISA. In a subgroup of animals, hearts were perfused according to Langendorff and were subjected to 35 min global ischemia and 120 min reperfusion with or without IPRE (3 × 5 min I/R cycles applied before index ischemia). Then infarct size or phosphorylated and total forms of proteins related to the cardioprotective RISK (AKT, ERK1,2) and SAFE (STAT3) pathways were measured by Western blot.

RESULTS

The severity of CKD was similar in males and females. However, CKD males developed more severe LVH compared to females as assessed by echocardiography. Histology revealed cardiac fibrosis only in males in CKD. LV ANP expression was significantly increased due to CKD in both sexes, however, LV BNP and circulating BNP levels failed to significantly increase in CKD. In both sexes, IPRE significantly decreased the infarct size in both the sham-operated and CKD groups. IPRE significantly increased the phospho-STAT3/STAT3 ratio in sham-operated but not in CKD animals in both sexes. There were no significant differences in phospho-AKT/AKT and phospho-ERK1,2/ERK1,2 ratios between the groups.

CONCLUSION

The infarct size-limiting effect of IPRE was preserved in both sexes in CKD despite the more severe uremic cardiomyopathy in male CKD rats. Further research is needed to identify crucial molecular mechanisms in the cardioprotective effect of IPRE in CKD.

Estrogen and estrogen receptors in kidney diseases

Acute kidney injury (AKI) and chronic kidney disease (CKD) are posing great threats to global health within this century. Studies have suggested that estrogen and estrogen receptors (ERs) play important roles in many physiological processes in the kidney. For instance, they are crucial in maintaining mitochondrial homeostasis and modulating endothelin-1 (ET-1) system in the kidney. Estrogen takes part in the kidney repair and regeneration via its receptors. Estrogen also participates in the regulation of phosphorus homeostasis via its receptors in the proximal tubule. The ERα polymorphisms have been associated with the susceptibilities and outcomes of several renal diseases. As a consequence, the altered or dysregulated estrogen/ERs signaling pathways may contribute to a variety of kidney diseases, including various causes-induced AKI, diabetic kidney disease (DKD), lupus nephritis (LN), IgA nephropathy (IgAN), CKD complications, etc. Experimental and clinical studies have shown that targeting estrogen/ERs signaling pathways might have protective effects against certain renal disorders. However, many unsolved problems still exist in knowledge regarding the roles of estrogen and ERs in distinct kidney diseases. Further research is needed to shed light on this area and to enable the discovery of pathway-specific therapies for kidney diseases.

Tamoxifen attenuates renal fibrosis in human kidney slices and rats subjected to unilateral ureteral obstruction

BACKGROUND AND PURPOSE

Renal fibrosis plays an important role in the development and progression of chronic kidney disease (CKD). Clinical studies have shown that CKD progresses differently in males and females, which may be related to circulating levels of sex hormones. In this study, we investigated the effect of tamoxifen (TAM), a selective estrogen receptor modulator (SERM), on renal fibrosis in male and female rats subjected to unilateral ureteral obstruction (UUO) and human precision-cut kidney slices (PCKS).

EXPERIMENTAL APPROACH

Female, ovariectomized female (OVX), and male rats were subjected to 7 days of UUO and treated with TAM by oral gavage. Moreover, we studied individual responses to TAM treatment in PCKS prepared from female and male patients. In all models, the expression of fibrosis markers was examined by western blot, qPCR, and immunohistochemistry.

KEY RESULTS

TAM decreased the expression of fibronectin, α-smooth muscle actin, and collagen-1 and -3 in female, OVX, and male rats. In addition, TAM mitigated TGF-β-induced fibrosis in human PCKS, irrespective of sex, yet interindividual differences in treatment response were observed.

CONCLUSION AND IMPLICATIONS

TAM ameliorates renal fibrosis in males and females, although we did observe sex differences in drug response. These findings warrant further research into the clinical applicability of TAM, or other SERMs, for the personalized treatment of renal disease.

Estrogen receptor agonists protect against acetaminophen-induced hepatorenal toxicity in rats

AIMS

Acetaminophen-induced hepatorenal toxicity varies among sexes with controversial results among species. The aim was to compare the impact of sex and ovarian hormones on hepatorenal toxicity and to elucidate protective effects of estrogen and estrogen receptor (ER) agonists.

MAIN METHODS

Under anesthesia, female rats underwent ovariectomy (OVX) or sham-OVX. Starting at postsurgical 40th day, OVX-rats received subcutaneously (each, 1 mg/kg/day) 17β-estradiol (E₂), ERβ-agonist (DPN) or ERα-agonist (PPT) for 10 days, while male and sham-OVX rats received vehicle for 10 days. Then, rats received either acetaminophen (3 g/kg) or saline by orogastric gavage and were decapitated at 24th h. Blood samples were obtained to measure serum ALT, AST, BUN, creatinine levels. Liver and kidney samples were obtained for histopathologic examination and for analyzing levels of luminol- and lucigenin-chemiluminescence, glutathione and myeloperoxidase activity.

KEY FINDINGS

Compared to their control groups, levels of AST, ALT, BUN, creatinine, hepatic and renal myeloperoxidase activity and chemiluminescence levels were increased, and hepatic glutathione level was decreased in acetaminophen-administered male groups, while ALT and hepatic chemiluminescence levels were not elevated in sham-OVX-rats. Both ER-agonists and E₂ reduced BUN, creatinine and reversed all oxidative parameters in renal tissues of OVX-rats. Additionally, ERα-agonist reversed all hepatic injury parameters, while ERβ-agonist elevated hepatic glutathione level.

SIGNIFICANCE

Acetaminophen toxicity in female rats presented with a more preserved hepatic function, while renal toxicity was not influenced by sex or by the lack of ovarian hormones. Pretreatment with estrogen or ER agonists, via their antioxidant actions, provided protective effects on acetaminophen-induced hepatorenal toxicity.

Oestrogen receptor ERα and ERβ agonists ameliorate oxidative brain injury and improve memory dysfunction in rats with an epileptic seizure

NEW FINDINGS

What is the central question of this study? Could different hormonally active substances, including oestrogen receptor (ER) agonists, protect against oxidative brain damage and memory impairment induced by a single epileptic seizure in rats? If so, which signalling mechanisms are involved in their anti-inflammatory effects? What is the main finding and its importance? Chronic administration of oestrogen, progesterone, ER modulators/agonists or blockade of testosterone exhibited anti-inflammatory and antioxidant actions on single seizure-induced neuronal injury, while ER agonists additionally improved memory function and up-regulated CREB signalling and hippocampal GABA(A)α1 receptor density, suggesting that ERα or ERβ receptor activation may be beneficial in protecting against seizure-related oxidative brain injury and cognitive dysfunction.

ABSTRACT

The susceptibility to epileptic seizures is dependent on sex as well as fluctuations in oestrogen levels, while exogenous oestrogen was shown to have no effect or to facilitate or to inhibit seizure activity. Oestrogen receptors (ERs) mediate antioxidant and anti-inflammatory actions in several inflammatory models, but the involvement of ERs in seizure-induced neuronal injury has not been evaluated previously. In order to assess the effects of resveratrol, progesterone, oestradiol (E2), an anti-testosterone (cyproterone acetate; CPA), a selective ER modulator (tamoxifen; TMX) and ERα/ERβ agonists (propyl pyrazole triol (PPT), diarylpropionitrile (DPN)) on oxidative brain damage and memory impairment due to epileptic seizure, male Wistar rats (n = 120) received one of the treatment choices either in drinking water or intraperitoneally for 31 days, and epileptic seizure was induced on the 28th day by injection of a single-dose of pentylenetetrazole (45 mg kg^-1 ). The results demonstrate that chronic pretreatment with resveratrol, progesterone, E2, CPA or TMX suppressed most of the inflammatory parameters indicative of oxidative neuronal injury, while treatment with the ER agonists DPN or PPT were found to be even more effective in limiting the oxidative damage. Treatment with DPN resulted in the up-regulation of cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) expression, while PPT up-regulated expression of CREB without affecting BDNF levels. Moreover, both ER agonists provided protection against seizure-induced memory loss with a concomitant increase in hippocampal GABA(A)α1-positive cells. In conclusion, ER agonists, and more specifically ERβ agonist, appear to provide maximum protection against seizure-induced oxidative brain injury and associated memory dysfunction by up-regulating the expression of CREB, BDNF and GABA(A)α1 receptors.

Quantitative reduction in short-chain fatty acids, especially butyrate, contributes to the progression of chronic kidney disease

Chronic kidney disease (CKD) affects 10-15% of the population worldwide, results in high morbidity and mortality, and requires costly treatment and renal replacement therapy. Glomerulosclerosis, tubulointerstitial fibrosis, and persistent intestinal flora disturbance are common in CKD. Short-chain fatty acids (SCFAs), produced by the intestinal microbiota, have been previously reported to ameliorate kidney injury; however, the specific concentrations and types that are required to improve renal function remain unknown. The present study aims to evaluate the levels of SCFAs in healthy and CKD patients, and to test the hypothesis that SCFAs play a critical role in delaying CKD progression. One hundred and twenty-seven patients with CKD and 63 healthy controls from China were enrolled in the present study. Butyrate, which is considered beneficial to humans, was almost three-times higher in healthy volunteers than that in CKD5 subjects (P=0.001). Moreover, the serum SCFA levels in controls were significantly higher than that in CKD patients (P<0.05), and the butyrate level among CKD5 patients (1.48 ± 0.60 μmol/l) was less than half of that in controls (3.44 ± 2.12 μmol/l, P<0.001). In addition, we observed an inverse correlation between butyrate level and renal function (P<0.05). A CKD rat model transplanted with microbiota obtained from CKD patients exhibited accelerated CKD progression via increased production of trimethylamine N-oxide (TMAO), which was reversed by supplementation with extra butyrate. Our results showed that SCFA levels were reduced in CKD patients and that butyrate supplementation might delay CKD progression.

Cardioprotective Mechanisms of Exenatide in Isoprenaline-induced Myocardial Infarction: Novel Effects on Myocardial α-Estrogen Receptor Expression and IGF-1/IGF-2 System

Myocardial infarction (MI) is one of the main causes of morbidity and mortality in diabetic patients. The antidiabetic glucagon-like polypeptide-1 receptor (GLP-1R) agonists, such as exenatide, proved to confer cardioprotection; however, their exact mechanisms are not fully elucidated. Although the cardioprotective effect of α-estrogen receptor (ERα) activation is well established, its involvement in exenatide-induced cardioprotection has never been investigated. Moreover, modulation of insulin-like growth factor-1/2 (IGF-1/IGF-2) system by exenatide, and the consequent effect on cardiomyocyte apoptosis, is yet to be established. Current study aimed to investigate the cardioprotective potential of exenatide versus the standard cardioprotective agent, 17β-estradiol, against isoprenaline (ISO)-induced MI in rats. MI-insulted group showed electrocardiographic abnormalities, elevated serum cardiac markers, higher serum IGF-2 level along with histopathological abnormalities. Treatment with exenatide and/or 17β-estradiol, commenced 8 weeks before ISO insult, ameliorated these anomalies with maximum cardioprotection achieved with combined treatment. This was associated with upregulation of both ERα and IGF-1R, and downregulation of IGF-2R in left ventricles. Inhibition of ERs in Langendorff preparations confirmed their involvement in mediating exenatide-induced cardioprotective effect. Current study showed that the GLP-1R agonist exenatide exerted cardioprotection associated with upregulation of ERα and modulation of IGF-1/IGF-2 signaling in favor of antiapoptosis.

Gender differences in trauma, shock and sepsis

Despite efforts in prevention and intensive care, trauma and subsequent sepsis are still associated with a high mortality rate. Traumatic injury remains the main cause of death in people younger than 45 years and is thus a source of immense social and economic burden. In recent years, the knowledge concerning gender medicine has continuously increased. A number of studies have reported gender dimorphism in terms of response to trauma, shock and sepsis. However, the advantageous outcome following trauma-hemorrhage in females is not due only to sex. Rather, it is due to the prevailing hormonal milieu of the victim. In this respect, various experimental and clinical studies have demonstrated beneficial effects of estrogen for the central nervous system, the cardiopulmonary system, the liver, the kidneys, the immune system, and for the overall survival of the host. Nonetheless, there remains a gap between the bench and the bedside. This is most likely because clinical studies have not accounted for the estrus cycle. This review attempts to provide an overview of the current level of knowledge and highlights the most important organ systems responding to trauma, shock and sepsis. There continues to be a need for clinical studies on the prevailing hormonal milieu following trauma, shock and sepsis.

Phenyl sulfate, indoxyl sulfate and p-cresyl sulfate decrease glutathione level to render cells vulnerable to oxidative stress in renal tubular cells

In chronic kidney disease patients, oxidative stress is generally associated with disease progression and pathogenesis of its comorbidities. Phenyl sulfate is a protein-bound uremic solute, which accumulates in chronic kidney disease patients, but little is known about its nature. Although many reports revealed that protein-bound uremic solutes induce reactive oxygen species production, the effects of these solutes on anti-oxidant level have not been well studied. Therefore, we examined the effects of protein-bound uremic solutes on glutathione levels. As a result, indoxyl sulfate, phenyl sulfate, and p-cresyl sulfate decreased glutathione levels in porcine renal tubular cells. Next we examined whether phenyl sulfate-treated cells becomes vulnerable to oxidative stress. In phenyl sulfate-treated cells, hydrogen peroxide induced higher rates of cell death than in control cells. Buthionine sulfoximine, which is known to decrease glutathione level, well mimicked the effect of phenyl sulfate. Finally, we evaluated a mixture of indoxyl sulfate, phenyl sulfate, and p-cresyl sulfate at concentrations comparable to the serum concentrations of hemodialysis patients, and we confirmed its decreasing effect on glutathione level. In conclusion, indoxyl sulfate, phenyl sulfate, and p-cresyl sulfate decrease glutathione levels, rendering the cells vulnerable to oxidative stress.

The influence of sex steroid hormones on the response to trauma and burn injury

Trauma and related sequelae result in disturbance of homeostatic mechanisms frequently leading to cellular dysfunction and ultimately organ and system failure. Regardless of the type and severity of injury, gender dimorphism in outcomes following trauma have been reported, with females having lower mortality than males, suggesting that sex steroid hormones (SSH) play an important role in the response of body systems to trauma. In addition, several clinical and experimental studies have demonstrated the effects of SSH on the clinical course and outcomes following injury. Animal studies have reported the ability of SSH to modulate immune, inflammatory, metabolic and organ responses following traumatic injury. This indicates that homeostatic mechanisms, via direct and indirect pathways, can be maintained by SSH at local and systemic levels and hence result in more favourable prognosis. Here, we discuss the role and mechanisms by which SSH modulates the response of the body to injury by maintaining various processes and organ functions. Such properties of sex hormones represent potential novel therapeutic strategies and further our understanding of current therapies used following injury such as oxandrolone in burn-injured patients.

The role of estrogen in cutaneous ageing and repair

Combined advances in modern medical practice and increased human longevity are driving an ever-expanding elderly population. Females are particularly at risk of age-associated pathology, spending more of their lives in a post-menopausal state. Menopause, denoted by a rapid decline in serum sex steroid levels, accelerates biological ageing across the body's tissues. Post-menopause physiological changes are particularly noticeable in the skin, which loses structural architecture and becomes prone to damage. The sex steroid most widely discussed as an intrinsic contributor to skin ageing and pathological healing is 17β-estradiol (or estrogen), although many others are involved. Estrogen deficiency is detrimental to many wound-healing processes, notably inflammation and re-granulation, while exogenous estrogen treatment widely reverses these effects. Over recent decades, many of the molecular and cellular correlates to estrogen's beneficial effect on normal skin homeostasis and wound healing have been reported. However, disparities still exist, particularly in the context of mechanistic studies investigating estrogen receptor signalling and its potential cellular effects. New molecular techniques, coupled with increased understanding of estrogen in skin biology, will provide further opportunities to develop estrogen receptor-targeted therapeutics.

Uraemia: an unrecognized driver of central neurohumoral dysfunction in chronic kidney disease?

Chronic kidney disease (CKD) carries a large cardiovascular burden in part due to hypertension and neurohumoral dysfunction - manifesting as sympathetic overactivity, baroreflex dysfunction and chronically elevated circulating vasopressin. Alterations within the central nervous system (CNS) are necessary for the expression of neurohumoral dysfunction in CKD; however, the underlying mechanisms are poorly defined. Uraemic toxins are a diverse group of compounds that accumulate as a direct result of renal disease and drive dysfunction in multiple organs, including the brain. Intensive haemodialysis improves both sympathetic overactivity and cardiac baroreflex sensitivity in renal failure patients, indicating that uraemic toxins participate in the maintenance of autonomic dysfunction in CKD. In rodents exposed to uraemia, immediate early gene expression analysis suggests upregulated activity of not only pre-sympathetic but also vasopressin-secretory nuclei. We outline several potential mechanisms by which uraemia might drive neurohumoral dysfunction in CKD. These include superoxide-dependent effects on neural activity, depletion of nitric oxide and induction of low-grade systemic inflammation. Recent evidence has highlighted superoxide production as an intermediate for the depolarizing effect of some uraemic toxins on neuronal cells. We provide preliminary data indicating augmented superoxide production within the hypothalamic paraventricular nucleus in the Lewis polycystic kidney rat, which might be important for mediating the neurohumoral dysfunction exhibited in this CKD model. We speculate that the uraemic state might serve to sensitize the central actions of other sympathoexcitatory factors, including renal afferent nerve inputs to the CNS and angiotensin II, by way of recruiting convergent superoxide-dependent and pro-inflammatory pathways.

Estrogens do not protect, but androgens exacerbate, collagen accumulation in the female mouse kidney after ureteric obstruction

AIMS

Controversy surrounds the gender basis of progression in chronic kidney disease. Unfortunately, most experimental studies addressing this question do not distinguish between direct effects of estrogen and indirect activation of estrogen receptors through conversion of testosterone to 17β-estradiol by aromatase. We examined the pathogenesis of renal fibrosis in female aromatase knockout (ArKO) mice, which lack circulating and stored estrogens, while having normal levels of testosterone.

MAIN METHODS

ArKO mice and their wild-type (ArWT) counterparts were subjected to unilateral ureteric obstruction (UUO), with kidney tissue collected at day(D) 0, 3 and 9 post-UUO. Effects of 5α-dihydrotestosterone (DHT) administration on each genotype were also studied. Tissue was assessed biochemically and histochemically for fibrosis. Western blot analysis was used to measure α-smooth muscle actin (α-SMA) expression and TGF-β1 signalling. Matrix metalloproteinase-2 (MMP-2) activity was measured by zymography.

KEY FINDINGS

UUO increased collagen content over time (p<0.05 (D3) and p<0.01 (D9) vs day 0), with no difference between genotypes in qualitative (collagen IV staining) and quantitative (hydroxyproline concentration) analyses. Systemic administration of non-aromatizable DHT increased collagen content after 3days of UUO in both genotypes. This was not paralleled by any change in α-SMA (myofibroblast burden) or TGF-β1 signalling but was commensurate with DHT reducing MMP2 activity in both genotypes (p<0.05 vs genotype controls).

SIGNIFICANCE

Physiological concentrations of estrogens do not protect the injured kidney from fibrosis progression. Androgens rather than estrogens are the relevant factor involved in regulating disease-related renal scarring in this model.

Gender differences in adenine-induced chronic kidney disease and cardiovascular complications in rats

Gender contributes to differences in incidence and progression of chronic kidney disease (CKD) and associated cardiovascular disease. To induce kidney damage in male and female Wistar rats (n = 12/group), a 0.25% adenine diet for 16 wk was used. Kidney function (blood urea nitrogen, plasma creatinine, proteinuria) and structure (glomerular damage, tubulointerstitial atrophy, fibrosis, inflammation); cardiovascular function (blood pressure, ventricular stiffness, vascular responses, echocardiography) and structure (cardiac fibrosis); plasma testosterone and estrogen concentrations; and protein expression for oxidative stress [heme oxygenase-1, inflammation (TNF-α), fibrosis (transforming growth factor-β), ERK1/2, and estrogen receptor-α (ER-α)] were compared in males and females. Adenine-fed females had less decline in kidney function than adenine-fed males, although kidney atrophy, inflammation, and fibrosis were similar. Plasma estrogen concentrations increased and plasma testosterone concentrations decreased in adenine-fed males, with smaller changes in females. CKD-associated molecular changes in kidneys were more pronounced in males than females except for expression of ER-α in the kidney, which was completely suppressed in adenine-fed males but unchanged in adenine-fed females. Both genders showed increased blood pressure, ventricular stiffness, and cardiac fibrosis with the adenine diet. Cardiovascular changes with adenine were similar in males and females, except males developed concentric, and females eccentric cardiac hypertrophy. In hearts from adenine-fed male and female rats, expression of ER-α and activation of the ERK1/2 pathway were increased, in part explaining changes in cardiac hypertrophy. In summary, adenine-induced kidney damage may be increased in males due to the suppression of ER-α.

Incidence and risk factors of chronic kidney disease in korean patients with t1a renal cell carcinoma before and after radical or partial nephrectomy

OBJECTIVE

The aim of the study was to investigate the incidence of chronic kidney disease in patients with T1a renal cell carcinoma both before and after partial or radical nephrectomy, and to assess risk factors for chronic kidney disease.

METHODS

From January 2001 to December 2011, 1928 patients with a single renal mass ≤4 cm undergoing partial nephrectomy or radical nephrectomy with the existence of a normal contralateral kidney were retrospectively reviewed for the evaluation of preoperative chronic kidney disease, and reviewed only 1676 patients for the postoperative chronic kidney disease. The estimated glomerular filtration rates were used to define chronic kidney disease <60 ml/min/1.73 m(2) by the Modification of Diet in Renal Disease equation. Demographics and clinicopathological parameters were evaluated to determine the risk factors with the development of chronic kidney disease both before and after surgery.

RESULTS

Chronic kidney disease was found preoperatively in 10.0% (n = 192) of patients; 16.1% (n = 269) of patients developed chronic kidney disease postoperatively, including 102 (6.1%) chronic kidney disease patients >65 years of age. Between the non-chronic kidney disease and chronic kidney disease patients, male gender (odds ratio 3.55 vs. 3.78, respectively) and diagnostic age (odds ratio 1.04 vs. 1.05) were significantly distinctive common risk factors for chronic kidney disease both before and after surgery (P < 0.002). In addition, hypertension (odds ratio 0.46), serum albumin (odds ratio 0.23) and calcium (odds ratio 2.06) were significant as preoperative risk factors (P < 0.015), and preoperative serum creatinine (odds ratio 1.90) and surgical type (partial nephrectomy or radical nephrectomy; odds ratio 11.89) were significant as postoperative risk factors (P < 0.030).

CONCLUSIONS

Old, male hypertensive patients with a small renal mass would be better candidates for partial nephrectomy to prevent postoperative chronic kidney disease.

Prevalence of albuminuria and associated cardiovascular risk factors: a community cohort in Namwon City, Korea

AIM

To document the prevalence of albuminuria and determine its relationship to risk factors for cardiovascular disease (CVD) among Korean adults.

METHODS

We performed a cross-sectional study of adults aged 45-74 years from Namwon City, South Korea. Albuminuria was defined as a urinary albumin-to-creatinine ratio (UACR)≥30mg/g. The values of UACR were categorized into 5 groups: <10, 10-19, 20-29, 30-299, and ≥300mg/g. Risk factors for CVD and the estimated glomerular filtration rate (eGFR) were analyzed for an association with UACR values.

RESULTS

Data were obtained from 10,534 participants (4140 men and 6394 women). Albuminuria was more prevalent among women than men (27.3% versus 22.7%, respectively, p<0.001), and it was also more prevalent among older participants (p<0.001). The prevalence of albuminuria was 36.3% among participants with hypertension or type 2 diabetes, and it was 16.6% among participants without these conditions. The UACR was positively associated with CVD risk factors, including blood pressure, obesity indexes, total cholesterol, and the eGFR.

CONCLUSIONS

The prevalence of albuminuria is high in the general population in Korea, even among Koreans without CVD risk factors. Lower UACR values are associated with reduced CVD risk factors.

Inhibition of estradiol synthesis attenuates renal injury in male streptozotocin-induced diabetic rats

We previously showed that the male streptozotocin (STZ)-induced diabetic rat exhibits decreased circulating testosterone and increased estradiol levels. While supplementation with dihydrotestosterone is partially renoprotective, the aim of the present study was to examine whether inhibition of estradiol synthesis, by blocking the aromatization of testosterone to estradiol using an aromatase inhibitor, can also prevent diabetes-associated renal injury. The study was performed on male Sprague-Dawley nondiabetic, STZ-induced diabetic, and STZ-induced diabetic rats treated with 0.15 mg/kg of anastrozole, an aromatase inhibitor (Da) for 12 wk. Treatment with anastrozole reduced diabetes-associated increases in plasma estradiol by 39% and increased plasma testosterone levels by 187%. Anastrozole treatment also attenuated urine albumin excretion by 42%, glomerulosclerosis by 30%, tubulointerstitial fibrosis by 32%, along with a decrease in the density of renal cortical CD68-positive cells by 50%, and protein expression of transforming growth factor-β by 20%, collagen type IV by 29%, tumor necrosis factor-α by 28%, and interleukin-6 by 25%. Anastrozole also increased podocin protein expression by 18%. We conclude that blocking estradiol synthesis in male STZ-induced diabetic rats is renoprotective.