Effects of sex hormones on mesangial cell proliferation and collagen synthesis

Reno-protective effect of protocatechuic acid is independent of sex-related differences in murine model of UUO-induced kidney injury

BACKGROUND

Obstructive nephropathy is a condition often caused by urinary tract obstruction either anatomical (e.g., tumors), mechanical (e.g., urolithiasis), or compression (e.g., pregnancy) and can progress to chronic kidney disease (CKD). Studies have shown sexual dimorphism in CKD, where males were found to have a more rapid decline in kidney function following kidney injury compared to age-matched females. Protocatechuic acid (PCA), an anti-oxidant and anti-inflammatory polyphenolic compound, has demonstrated promising effects in mitigating drug-induced kidney injuries. The current study aims to explore sexual dimorphism in kidney injury after unilateral ureteral obstruction (UUO) and assess whether PCA treatment can mitigate kidney injury in both sexes.

METHODS

UUO was induced in 10-12 weeks old male and female C57BL/6J mice. Mice were categorized into four groups (n = 6-8/group); Sham, Sham plus PCA (100 mg/kg, I.P daily), UUO, and UUO plus PCA.

RESULTS

After 2 weeks of induction of UUO, markers of kidney oxidative stress (TBARs), inflammation (IL-1α and IL-6), tubular injury (neutrophil gelatinase-associated lipocalin, NGAL and urinary kidney injury molecule-1, KIM-1), fibrosis (Masson's trichrome staining, collagen IV expression, MMP-2 and MMP-9) and apoptosis (TUNEL+ cells, active caspase-1 and caspase-3) were significantly elevated in both males and females relative to their sham counterparts. Males exhibited significantly greater kidney oxidative stress, inflammation, fibrosis, and apoptosis after induction of UUO when compared to females. PCA treatment significantly attenuated UUO-induced kidney injury, inflammation, fibrosis, and apoptosis in both sexes.

CONCLUSION

Our findings suggest a differential gender response to UUO-induced kidney injury with males being more sensitive to UUO-induced kidney inflammation, fibrosis, and apoptosis than age-matched females. Importantly, PCA treatment reduced UUO-induced kidney injury in a sex-independent manner which might be attributed to its anti-oxidant, anti-inflammatory, anti-fibrotic, and anti-apoptotic properties.

The association between visceral adiposity index and chronic kidney disease in the elderly: A cross-sectional analysis of NHANES 2011-2018

Visceral adiposity index (VAI) is a new metric for evaluating visceral adiposity dysfunction. The aim of the present study was to explore the association between VAI and incident chronic kidney disease (CKD) in the American elderly population. We included 6085 participants aged 60 years or older with available data on renal function and VAI from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2018 and divided them into four groups according to the VAI quartiles. VAI values were ln-transformed to reduce skewness. We conducted multivariable logistic regression analyses and spline smoothing plot analyses to evaluate the association between VAI and CKD. After fully adjusting for confounding factors, higher lnVAI was associated with a higher risk of CKD (OR, 1.23; 95 %CI, 1.02, 1.48). Compared to the Q1 group (VAI < 1.1), The third and fourth VAI quartiles were associated with a higher prevalence of CKD (Q3: VAI, 1.8-3.0; Q4: VAI > 3.0). The adjusted ORs (95% CI) in Q3 and Q4 were 1.74 (1.24, 2.42) and 1.59 (1.08, 2.33). Adjusted smoothed plots suggested a nonlinear relationship between lnVAI and CKD. The development of CKD increased with increasing VAI among participants with a lnVAI between -0.6 and 1.6 (VAI: 0.5-5.0). In conclusion, VAI is significantly associated with the risk of CKD in the US elderly population aged 60 years or older.

Role of sex hormones in diabetic nephropathy

Diabetic nephropathy (DN) is the most common microvascular complication in diabetes and one of the leading causes of end-stage renal disease. The standard treatments for patients with classic DN focus on blood glucose and blood pressure control, but these treatments can only slow the progression of DN instead of stopping or reversing the disease. In recent years, new drugs targeting the pathological mechanisms of DN (e.g., blocking oxidative stress or inflammation) have emerged, and new therapeutic strategies targeting pathological mechanisms are gaining increasing attention. A growing number of epidemiological and clinical studies suggest that sex hormones play an important role in the onset and progression of DN. Testosterone is the main sex hormone in males and is thought to accelerate the occurrence and progression of DN. Estrogen is the main sex hormone in females and is thought to have renoprotective effects. However, the underlying molecular mechanism by which sex hormones regulate DN has not been fully elucidated and summarized. This review aims to summarize the correlation between sex hormones and DN and evaluate the value of hormonotherapy in DN.

Sex differences in cardiac remodeling post myocardial infarction with acute cigarette smoking

Background

Whether cigarette smoking affects the heart post-myocardial infarction (MI) in a sex-dependent way remains controversial. Using a mouse model, we investigated cardiac remodeling under the influence of acute cigarette smoke (CS) exposure following ischemic injury in both sexes.

Methods

Ten cigarettes were smoked twice daily for 2 weeks followed by MI and then 1 additional week post permanent LAD ligation. Cardiac function, histology, and infarct size were assessed, and inflammatory markers quantified by RT–PCR. Statistical comparisons were performed using an unpaired t test or ANOVA followed by Tukey post hoc test.

Results

We observed that cigarette smoking exacerbated both left and right ventricular remodeling only in males at an early stage of post-MI. Females did not display a significant structural and/or functional alteration within 7 days of cardiac remodeling post-MI upon CS exposure. Worsened right ventricular remodeling in males was independent of pulmonary congestion. CS-exposed males exhibited enhanced increases in left ventricular end systolic and diastolic volumes, as well as reductions in ejection fraction and fractional area changes of left ventricular base. At day 7, infarct size was increased by cigarette smoking in males only, which was accompanied by enhanced collagen deposition in both the infarcted and peri-infarcted areas. Both IL-6 and TNF-α mRNA expression significantly increased in CS-exposed MI male group only at day 7 post-MI suggestive of prolonged inflammation.

Conclusions

These findings indicate that CS exposure worsens the progression of cardiac remodeling post-MI in male sex in a significant manner compared to female sex at least at early stages.

Genetic polymorphisms related to muscular strength and flexibility are associated with artistic gymnastic performance in the Japanese population

This study aimed to examine how genetic polymorphisms related to muscular strength and flexibility influence artistic gymnastic performance in an attempt to identify a novel polymorphism associated with flexibility. In study 1, the passive straight-leg-raise (PSLR) score and aromatase gene CYP19A1 rs936306 polymorphism, a key enzyme for estrogen biosynthesis, were assessed in 278 individuals. In study 2, athletes (281 gymnasts and 1908 other athletes) were asked about their competition level, and gymnasts were assessed using the difficulty score (D-score) for each event. Muscular strength- (ACTN3 R577X rs1815739 and ACE I/D rs4341) and flexibility-related (ESR1 rs2234693 T/C and CYP19A1 rs936306 C/T) genetic polymorphisms were analyzed. In study 1, males with the CYP19A1 CT + TT genotype showed significantly higher PSLR scores than those with the CC genotype. In study 2, male gymnasts with the R allele of ACTN3 R577X showed a correlation with the floor, rings, vault, and total D-scores. In addition, male gymnasts with the C allele of ESR1 T/C and T allele of CYP19A1 C/T polymorphisms were correlated with the pommel horse, parallel bars, horizontal bar, and total D-scores. Furthermore, genotype scores of these three polymorphisms correlated with the total D-scores and competition levels in male gymnasts. In contrast, no such associations were observed in female gymnasts. Our findings suggest that muscular strength- and flexibility-related polymorphisms play important roles in achieving high performance in male artistic gymnastics by specifically influencing the performance of events that require muscular strength and flexibility, respectively. HighlightsEstrogen-related CYP19A1 polymorphism is a novel determinant of flexibility in males.Muscular strength- and flexibility-related polymorphisms play important roles in high performance in male artistic gymnastics.Genotypes of ACTN3 R577X, ESR1 rs2234693, and CYP19A1 rs936306 may contribute to training plan optimization and event selection in artistic gymnastics.

Association between Body Mass Index and Chronic Kidney Disease in Asian Populations: A Participant-level Meta-Analysis

Obesity and chronic kidney disease (CKD) are major public health problems worldwide. However, the association between body mass index (BMI) and CKD is inconclusive in Asians. In this meta-analysis, eight population-based studies, from China, India, Russia (Asian), Singapore and South Korea, provided individual-level data (n=50037). CKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m². BMI was analyzed both as a continuous variable and in three categories: <25kg/m², normal; 25-29.9kg/m², overweight; and ≥30kg/m², obese. The association between BMI and CKD was evaluated in each study using multivariable logistic regression models and individual estimates were pooled using random-effect meta-analysis to obtain the pooled odds ratio (OR) and 95% confidence interval (CI). Associations were also evaluated in subgroups of age, gender, smoking, diabetes, and hypertension status. Of 50037 adults, 4258 (8.5%) had CKD. 13328 (26.6%) individuals were overweight while 4440 (8.9%) were obese. The prevalence of any CKD ranged from 3.5% to 29.1% across studies. In pooled analysis, both overweight and obesity were associated with increased odds of CKD, with pooled OR (95% CI) of 1.15 (1.03-1.29) and 1.23 (1.06-1.42), respectively. In subgroup analyses, significant associations between BMI and CKD were observed in adult males, non-smokers, and those with diabetes and arterial hypertension (all p<0.05). When evaluated as a continuous variable, BMI was not significantly associated with CKD. If confirmed in longitudinal studies, these results may have clinical implications in risk stratification and preventive measures, given that obesity and CKD are two major chronic diseases with substantial public health burden worldwide.

Ankle-brachial index predicts renal outcomes and all-cause mortality in high cardiovascular risk population: a nationwide prospective cohort study in CORE project

BACKGROUND

Low ankle-brachial index (ABI) related ischemic events are common among individuals with chronic kidney disease (CKD). It is also associated with an increased risk of rapid renal function decline. The presence of peripheral artery disease (PAD) with low ABI among patients with high cardiovascular (CV) risk increases limb loss and mortality.

AIMS

To estimate the association between abnormal ABI and renal endpoints and all-cause mortality.

METHODS

A multicenter prospective cohort study was conducted among subjects with high CV risk or established CV diseases in Thailand. The subjects were divided into 3 groups based on ABI at baseline > 1.3, 0.91-1.3, and ≤ 0.9, respectively. Primary composite outcome consisted of estimated glomerular filtration rate (eGFR) decline over 40%, eGFR less than 15 mL/min/1.73 m², doubling of serum creatinine and initiation of dialysis. The secondary outcome was all-cause mortality. Cox regression analysis and Kaplan-Meier curve were performed.

RESULTS

A total of 5543 subjects (3005 men and 2538 women) were included. Cox proportional hazards model showed a significant relationship of low ABI (ABI ≤ 0.9) and primary composite outcome and all-cause mortality. Compared with the normal ABI group (ABI 0.91-1.3), subjects with low ABI at baseline significantly had 1.42-fold (95% CI 1.02-1.97) and 2.03-fold (95% CI 1.32-3.13) risk for the primary composite outcome and all-cause mortality, respectively, after adjusting for variable factors.

CONCLUSION

Our study suggested that PAD independently predicts the incidence of renal progression and all-cause mortality among Thai patients with high CV risk.

Female Athletes Genetically Susceptible to Fatigue Fracture Are Resistant to Muscle Injury: Potential Role of COL1A1 Variant

PURPOSE

We aimed to investigate the hypothesis that type I collagen plays a role in increasing bone mineral density (BMD) and muscle stiffness, leading to low and high risks of fatigue fracture and muscle injury, respectively, in athletes. As a potential mechanism, we focused on the effect of the type I collagen alpha 1 chain gene (COL1A1) variant associated with transcriptional activity on bone and skeletal muscle properties.

METHODS

The association between COL1A1 rs1107946 and fatigue fracture/muscle injury was evaluated in Japanese athletes. Effects of the polymorphism on tissue properties (BMD and muscle stiffness) and type I collagen α1/α2 chain ratios in muscles were examined in Japanese nonathletes.

RESULTS

The C-allele carrier frequency was greater in female athletes with fatigue fracture than in those without (odds ratio = 2.44, 95% confidence interval [CI] = 1.17-5.77) and lower in female athletes with muscle injury than in those without (odds ratio = 0.46, 95% CI = 0.24-0.91). Prospective validation analysis confirmed that in female athletes, muscle injury was less frequent in C-allele carriers than in AA genotype carriers (multivariable-adjusted hazard ratio = 0.27, 95% CI = 0.08-0.96). Among female nonathletes, the C-allele of rs1107946 was associated with lower BMD and lower muscle stiffness. Muscle biopsy revealed that C-allele carriers tended to have a larger type I collagen α1/α2 chain ratio than AA genotype carriers (2.24 vs 2.05, P = 0.056), suggesting a higher proportion of type I collagen α1 homotrimers.

CONCLUSION

The COL1A1 rs1107946 polymorphism exerts antagonistic effects on fatigue fracture and muscle injury among female athletes by altering the properties of these tissues, potentially owing to increased levels of type I collagen α1 chain homotrimers.

Association between obesity and urinary albumin-creatinine ratio in the middle-aged and elderly population of Southern and Northern China: a cross-sectional study

OBJECTIVE

The relationship between obesity and albuminuria has not been clarified. This study aimed to investigate the correlation between obesity and the urinary albumin-creatinine ratio (UACR) in Southern and Northern China.

DESIGN

A descriptive, cross-sectional study.

SETTING

Eight regional centres in REACTION (China's Risk Evaluation of cAncers in Chinese diabeTic Individuals, a lONgitudinal study), including Dalian, Lanzhou, Zhengzhou, Guangzhou, Guangxi, Luzhou, Shanghai and Wuhan.

PARTICIPANTS

A total of 41 085 patients who were not diagnosed with chronic kidney disease (CKD) and had good compliance were selected according to the inclusion criteria. Patients who were diagnosed with CKD, who had other kidney diseases that could lead to increased urinary protein excretion, who were using angiotensin-converting-enzyme inhibitors or angiotensin II receptor blockers and whose important data were missing were excluded.

RESULTS

Participants with both, central and peripheral obesity, had a higher risk of elevated UACR, even after adjusting for multiple factors (OR: 1.14, 95% CI: 1.07 to 1.12, p<0.001), and the risk of high UACR in the South was more prominent than that in the North (OR _South: 1.22, 95% CI: 1.11 to 1.34; OR _North: 1.13, 95% CI: 1.04 to 1.22, p<0.001). The risk was also elevated in the male population, hypertensive individuals, glycosylated haemoglobin (HbA1c)≥6.5% and age ≥60 years in the South. Besides the above groups, diabetes was also a risk factor for the Northern population.

CONCLUSIONS

In China, people with both central and peripheral obesity are prone to a high UACR, and the southern population has a higher risk than northern population. Factors such as male sex, hypertension, HbA1c≥6.5% and an age ≥60 years are also risk factors for CKD.

Gender Differences in the Association Between Obesity Indices and Chronic Kidney Disease Among Middle-Aged and Elderly Taiwanese Population: A Community-Based Cross-Sectional Study

BACKGROUND

Traditional risk factors for chronic kidney disease (CKD) include diabetes mellitus (DM), hypertension (HTN), and metabolic syndrome, which are health conditions related to obesity. We aimed to investigate which of the three obesity indices has the strongest association with CKD and to explore whether there are gender differences in these relationships in the middle-aged and elderly Taiwanese population.

METHODS

This was a cross-sectional, community-based study. It included 400 residents (141 males and 259 females, age 50-90 years) residing in a community in northern Taiwan. Each participant was asked to fill a questionnaire that collected personal information, medical history, medication use, and anthropometric measurements. The laboratory data were obtained by testing the blood and urine samples. The baseline characteristics were compared, and the obesity indices included body mass index (BMI), waist circumference (WC), and visceral adiposity index (VAI). CKD was defined as the presence of renal dysfunction (urine albumin-creatinine ratio ≥ 30 mg/g) or estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73m². We used a multiple logistic regression model to evaluate the association between each obesity index and CKD for both genders. Further, we used the area under the receiver operating characteristic (ROC) curve (AUC) to examine the best obesity indices to predict CKD in different genders.

RESULTS

The average age of the subjects was 64.47 ± 8.45 years, and men were significantly older. CKD was found in 31 (22.0%) males and 50 (19.3%) females. In men, there was no significant difference between the CKD and non-CKD groups among the three obesity indices. However, in women, only VAI was significantly higher in subjects with CKD (1.9 [1.1, 3.4]) than in subjects without CKD (1.5 [1.0, 2.2]) (p-value = 0.03). The multivariate logistic regression revealed that even after adjusting for possible confounding factors, VAI was found to be an independent risk factor for CKD in women (OR: 1.32, 95% CI: 1.04-1.69, p = 0.02), but not in men (OR: 1.20, 95% CI: 0.85-1.69, p = 0.30). The AUC of VAI had a significant ability to predict CKD in women but not in men.

CONCLUSION

Our results showed that among the three obesity indices, VAI had the strongest association with CKD compared to BMI and WC in women. In addition, VAI in women should be given more importance in the screening for CKD among the middle-aged and elderly Taiwanese population.

Association of Reproductive Lifespan Duration and Chronic Kidney Disease in Postmenopausal Women

OBJECTIVE

To investigate the relationship between endogenous estrogen exposure and renal function, the association of female reproductive life span duration (RLD) and chronic kidney disease (CKD) was analyzed in postmenopausal women.

PATIENTS AND METHODS

Data were retrieved from the Korean Genome and Epidemiology Study, which was constructed from May 1, 2001, through December 25, 2017. A total of 50,338 and 3155 postmenopausal women were each included in the cross-sectional and longitudinal analyses. The RLD was determined by subtracting the age at menarche from the age at menopause. Participants were grouped into RLD quartiles. Participants with estimated glomerular filtration rates less than 60 mL/min/1.73 m² were regarded to have CKD.

RESULTS

In the cross-sectional analysis, mean ± SD age and estimated glomerular filtration rate were 56.3±4.9 years and 93.1±13.6 mL/min/1.73 m², respectively. Mean ± SD RLD was 34.2±4.0 years. A total of 765 of 50,338 (1.52%) women were found to have CKD. Logistic regression analysis revealed that the odds ratio for CKD was lower in groups with longer RLDs as compared with the shortest RLD group. In longitudinal analysis, postmenopausal women with normal kidney function were followed up for 9.7 years and incident CKD occurred in 221 of 3155 (7.00%) participants. Cox analysis revealed that the risk for CKD development was significantly lower in longer RLD groups. This finding was significant even after adjustments for confounding factors.

CONCLUSION

The risk for CKD was lower in women with longer RLDs. The amount of endogenous estrogen exposure could be a determining factor for renal function in postmenopausal women.

Kidney size in relation to ageing, gender, renal function, birthweight and chronic kidney disease risk factors in a general population

BACKGROUND

The relationship of kidney size to ageing, kidney function and kidney disease risk factors is not fully understood.

METHODS

Ultrasound length and parenchymal kidney volume were determined from a population-based sample of 3972 Sardinians (age range 18-100 years). We then identified the subset of 2256 'healthy' subjects to define age- and sex-specific reference ranges (2.5-97.5 percentile) of kidney volume. Logistic regression (accounting for family clustering) was used to identify the clinical characteristics associated with abnormally large kidneys or abnormally small kidneys.

RESULTS

In the healthy subset, kidney volume and length increased up to the fourth to fifth decade of life followed by a progressive decrease in men, whereas there was a gradual kidney volume decrease throughout the lifespan of women. In the whole sample, independent predictors of lower kidney volume (<2.5 percentile for age and sex) were male sex, low body mass index, short height, low waist:hip ratio and high serum creatinine (SCr); the independent predictors of larger kidney volume (>97.5 percentile for age and sex) were younger age, female sex, diabetes, obesity, high height, high waist:hip ratio and lower SCr. Estimated heritability for kidney volume was 15%, and for length 27%; kidney volume correlated strongly with birthweight.

CONCLUSIONS

Overall, in a general healthy population, kidney measures declined with age differently in men and women. The determinants of kidney parenchymal volume include genetic factors and modifiable clinical factors.

Genetics of Muscle Stiffness, Muscle Elasticity and Explosive Strength

Muscle stiffness, muscle elasticity and explosive strength are the main components of athletes' performance and they show a sex-based as well as ethnicity variation. Muscle stiffness is thought to be one of the risk factors associated with sports injuries and is less common in females than in males. These observations may be explained by circulating levels of sex hormones and their specific receptors. It has been shown that higher levels of estrogen are associated with lower muscle stiffness responsible for suppression of collagen synthesis. It is thought that these properties, at least in part, depend on genetic factors. Particularly, the gene encoding estrogen receptor 1 (ESR1) is one of the candidates that may be associated with muscle stiffness. Muscle elasticity increases with aging and there is evidence suggesting that titin (encoded by the TTN gene), a protein that is expressed in cardiac and skeletal muscles, is one of the factors responsible for elastic properties of the muscles. Mutations in the TTN gene result in some types of muscular dystrophy or cardiomyopathy. In this context, TTN may be regarded as a promising candidate for studying the elastic properties of muscles in athletes. The physiological background of explosive strength depends not only on the muscle architecture and muscle fiber composition, but also on the central nervous system and functionality of neuromuscular units. These properties are, at least partly, genetically determined. In this context, the ACTN3 gene code for α-actinin 3 has been widely researched.

Sex related differences in the pathogenesis of organ fibrosis

The development of organ fibrosis has garnered rising attention as multiple diseases of increasing and/or high prevalence appear to progress to the chronic stage. Such is the case for heart, kidney, liver, and lung where diseases such as diabetes, idiopathic/autoimmune disorders, and nonalcoholic liver disease appear to notably drive the development of fibrosis. Noteworthy is that the severity of these pathologies is characteristically compounded by aging. For these reasons, research groups and drug companies have identified fibrosis as a therapeutic target for which currently, there are essentially no effective options. Although a limited body of published studies are available, most literature indicates that in multiple organs, premenopausal women are protected from developing severe forms of fibrosis suggesting an important role for sex hormones in mitigating this process. Investigators have implemented relevant animal models of organ disease linked to fibrosis supporting in general, these observations. In vitro studies and transgenic animals models have also been used in an attempt to understand the role that sex hormones and related receptors play in the development of fibrosis. However, in the setting of chronic disease in some organs such as the heart older (postmenopausal) women within a few years can quickly approach men in disease severity and develop significant degrees of fibrosis. This review summarizes the current body of relevant literature and highlights the imperative need for a major focus to be placed on understanding the manner in which sex and the presence or absence of related hormones modulates cell phenotypes so as to allow for fibrosis to develop.

Reference values and sex differences in absolute and relative kidney size. A Swiss autopsy study

Background

Men have larger kidneys than women, but it is unclear whether gender remains an independent predictor of kidney size (expressed as weight or length) after correction for body size. We analysed autopsy data to assess whether relative renal length and weight (e.g. corrected for body weight, height or body surface area (BSA)) are also larger in men. Assuming that kidney size is associated with nephron number, opposite findings could partly explain why women are less prone to the development and progression of chronic kidney disease than men.

Methods

All forensic autopsies performed between 2009 and 2015 at the local university hospital of Geneva in individuals of European descent aged ≥18 years without a known history of diabetes and/or kidney disease were examined. Individuals with putrefied or severely injured bodies were excluded. Relative renal weight and length were respectively defined as renal weight divided by body weight or BSA and renal length divided by body height or BSA.

Results

A total of 635 autopsies (68.7% men) were included in the analysis. Left kidneys were on average 8 g heavier and 2 mm longer than right kidneys (both: p < 0.05). Absolute renal weight (165 ± 40 vs 122 ± 29 g) and length (12.0 ± 1.3 vs 11.4 ± 1.1 cm) were higher in men. Relative renal weight was also higher in men, but relative renal length was larger in women. In multivariable regression analysis, body height, body weight, the degree of blood congestion or depletion at autopsy and age were determinants of renal weight, whereas arterial hypertension and smoking were not. Percentile curves of renal weight and length according to sex and body height were constructed.

Conclusion

Absolute and relative renal weights were both smaller in women. This is in line with recent studies stating that nephron numbers are also lower in women. Relative renal length was longer in women, suggesting that female kidneys have a more elongated shape. In comparison with older autopsy studies, renal weight appears to be stable over time.

Estrogen-related mechanisms in sex differences of hypertension and target organ damage

Hypertension (HTN) is a primary risk factor for cardiovascular (CV) events, target organ damage (TOD), premature death and disability worldwide. The pathophysiology of HTN is complex and influenced by many factors including biological sex. Studies show that the prevalence of HTN is higher among adults aged 60 and over, highlighting the increase of HTN after menopause in women. Estrogen (E2) plays an important role in the development of systemic HTN and TOD, exerting several modulatory effects. The influence of E2 leads to alterations in mechanisms regulating the sympathetic nervous system, renin-angiotensin-aldosterone system, body mass, oxidative stress, endothelial function and salt sensitivity; all associated with a crucial inflammatory state and influenced by genetic factors, ultimately resulting in cardiac, vascular and renal damage in HTN. In the present article, we discuss the role of E2 in mechanisms accounting for the development of HTN and TOD in a sex-specific manner. The identification of targets with therapeutic potential would contribute to the development of more efficient treatments according to individual needs.

Perioperative Considerations Regarding Sex in Solid Organ Transplantation

Sex plays a role in all stages of the organ transplant process, including listing, sex/size matching of organs, complications, graft survival, and mortality. Sex-related differences in organ transplantation are likely multifactorial related to biological and social characteristics. More information is needed to determine how sex-related differences can lead to improved outcomes for future donors and recipients of solid organs. This article provides an overview on the impact of sex on various types of solid organ transplant, including kidney, pancreas, liver, lung, and heart transplants.

Sex differences in progression of diabetic nephropathy in OVE26 type 1 diabetic mice

AIMS

OVE26 mice (FVB background), genetically overexpressing calmodulin in pancreatic beta cells, develop early onset type 1 diabetes, leading to progressive diabetic nephropathy (DN), with features of established human DN. The role of gender in characteristics of renal lesions has remained unexplored.

METHODS

Male and female OVE26 mice were compared to age and sex matched wild-type, nondiabetic FVB mice at ages of 4, 12, 24 and 36 weeks. Nephropathy was examined by measuring urine albumin-to-creatinine ratio, histopathology, expression of pathological markers and immunochemistry in the same cohort of mice.

RESULTS

Progression of diabetic kidney disease was evident first in the OVE26 glomerulus, initially as mesangial matrix expansion at 4 weeks followed by loss of podocytes, glomerular volume expansion and severe albuminuria at 12 weeks. Tubule dilation and initiation of interstitial fibrosis did not become significant until 24 weeks. T-lymphocyte infiltration into the renal parenchyma appeared at 36 weeks. OVE26 female mice developed more advanced DN than male OVE26 mice, such as more severe albuminuria, greater podocyte loss, additional fibrosis and significantly more inflammatory cell infiltration. The female OVE26 mice had lowest level of plasma estradiol in all 36 weeks old mice, as well as renal estrogen receptors.

CONCLUSIONS

This demonstration of the role of gender, combined with the detailed characterization of DN progression illustrates the value of OVE26 mice for understanding gender effects on DN and provides the basis for researchers to better select the age and sex of OVE26 mice in future studies of type 1 DN.

RESEARCH IN CONTEXT

What is already known about this subject? What is the key question? What are the new findings? How might this impact on clinical practice in the foreseeable future?

ESR1 rs2234693 Polymorphism Is Associated with Muscle Injury and Muscle Stiffness

Supplemental digital content is available in the text.

Purpose

Muscle injury is the most common sports injury. Muscle stiffness, a risk factor for muscle injury, is lower in females than in males, implying that sex-related genetic polymorphisms influence muscle injury associated with muscle stiffness. The present study aimed to clarify the associations between two genetic polymorphisms (rs2234693 and rs9340799) in the estrogen receptor 1 gene (ESR1) and muscle injury or muscle stiffness.

Methods

In study 1, a questionnaire was used to assess the muscle injury history of 1311 Japanese top-level athletes. In study 2, stiffness of the hamstring muscles was assessed using ultrasound shear wave elastography in 261 physically active young adults. In both studies, rs2234693 C/T and rs9340799 G/A polymorphisms in the ESR1 were analyzed using the TaqMan SNP Genotyping Assay.

Results

In study 1, genotype frequencies for ESR1 rs2234693 C/T were significantly different between the injured and noninjured groups in a C-allele dominant (CC + CT vs TT: odds ratio, 0.62; 95% confidence interval, 0.43–0.91) and additive (CC vs CT vs TT: odds ratio, 0.70; 95% confidence interval, 0.53–0.91) model in all athletes. In study 2, hamstring muscle stiffness was lower in subjects with the CC + CT genotype than in those with the TT genotype; a significant linear trend (CC < CT < TT) was found (r = 0.135, P = 0.029). In contrast, no associations were observed between ESR1 rs9340799 G/A and muscle injury or stiffness.

Conclusions

Our results suggest that the ESR1 rs2234693 C allele, in contrast to the T allele, provides protection against muscle injury by lowering muscle stiffness.

Associations of passive muscle stiffness, muscle stretch tolerance, and muscle slack angle with range of motion: individual and sex differences

Joint range of motion (ROM) is an important parameter for athletic performance and muscular injury risk. Nonetheless, a complete description of muscular factors influencing ROM among individuals and between men and women is lacking. We examined whether passive muscle stiffness (evaluated by angle-specific muscle shear modulus), tolerance to muscle stretch (evaluated by muscle shear modulus at end-ROM), and muscle slack angle of the triceps surae are associated with the individual variability and sex difference in dorsiflexion ROM, using ultrasound shear wave elastography. For men, ROM was negatively correlated to passive muscle stiffness of the medial and lateral gastrocnemius in a tensioned state and positively to tolerance to muscle stretch in the medial gastrocnemius. For women, ROM was only positively correlated to tolerance to muscle stretch in all muscles but not correlated to passive muscle stiffness. Muscle slack angle was not correlated to ROM in men and women. Significant sex differences were observed only for dorsiflexion ROM and passive muscle stiffness in a tensioned state. These findings suggest that muscular factors associated with ROM are different between men and women. Furthermore, the sex difference in dorsiflexion ROM might be attributed partly to that in passive muscle stiffness of plantar flexors.

Gender Differences in the Progression of Experimental Chronic Kidney Disease Induced by Chronic Nitric Oxide Inhibition

Chronic kidney disease (CKD) is considered a public health problem, assuming epidemic proportions worldwide. In this context, the preponderance of CKD prevalence in male over age-matched female patients is of note. In the present study, we investigated the impact of the gender on the development of experimental CKD induced by chronic nitric oxide (NO) inhibition in Wistar male and female rats through the administration of L-NAME. CKD model induced by L-NAME is characterized by systemic vasoconstriction, resulting in severe hypertension, albuminuria, renal ischemia, glomerulosclerosis, interstitial expansion, and macrophage infiltration. After 30 days of CKD induction, male NAME rats exhibited remarkable albuminuria, augmented cortical histological damage, interstitial inflammation, and fibrosis. Age-matched female NAME rats showed significantly lower albuminuria, diminished glomerular ischemia, and glomerulosclerosis, as well as a significant reduction in the expression of α-smooth muscle actin renal interstitial Ang II+ cells. Thus, the present study demonstrated that female rats submitted to the NAME model developed less severe CKD than males. Female renoprotection could be promoted by both the estrogen anti-inflammatory activity and/or by the lack of testosterone, related to renin-angiotensin-aldosterone system hyperactivation and fibrogenesis. However, the influence of sex hormones on the progression of CKD needs to be further investigated.

Gender Differences in the Acute Kidney Injury to Chronic Kidney Disease Transition

This study evaluated if there is a sexual dimorphism in the acute kidney injury (AKI) to chronic kidney disease (CKD) transition and the time-course of the potential mechanisms involved in the dimorphic response. Female and male rats were divided into sham-operated or underwent 45-min renal ischemia (F + IR, and M + IR). All groups were studied at 24-h and 1, 2, 3, or 4-months post-ischemia. Additionally, oophorectomized rats were divided into sham or IR groups. After 24-h, AKI extent was simllar in females and males, but female rats exhibited less oxidative stress and increased renal GSH content. After 4-months and despite similar AKI, the M + IR group developed CKD characterized by proteinuria, tubulointerstitial fibrosis, glomerular hypertrophy, increased oxidative stress and a reduction in HIF1α and VEGF from the 1^st-month and persisting throughout the time-course studied. Interestingly, the F + IR group did not develop CKD due to lesser oxidative stress and increased eNOS, TGFβ and HIF1α mRNA levels from the 1^st-month after IR. Whereas, oophorectomized rats did develop CKD. We found a sexual dimorphic response in the AKI to CKD transition. Early antioxidant defense and higher TGFβ, HIF1α and eNOS were among the renoprotective mechanisms that the F + IR group demonstrated.

Association Between Obesity and Chronic Kidney Disease, Defined by Both Glomerular Filtration Rate and Albuminuria, in Korean Adults

BACKGROUND

Chronic kidney disease (CKD) has often been defined based on glomerular filtration rate (GFR) alone. The Kidney Disease: Improving Global Outcomes guideline highlights albuminuria in the CKD definition. Thus, we investigated the association between obesity and CKD, as defined by both GFR and albuminuria, in Korean adults.

METHODS

We used Korea National Health and Nutrition Examination Survey 2011-2014 data (N = 19,331, ≥19 years old) representing the national Korean population. CKD was classified by (1) estimated GFR (eGFR) < 60 mL/min/1.73 m² (CKD_GFR); (2) albumin-to-creatinine ratio (ACR) ≥30 mg/gram (CKD_ACR); and (3) eGFR < 60 mL/min/1.73 m² or ACR ≥30 mg/gram (CKD_Risk). Associations between obesity and each CKD category were evaluated using multivariate logistic regression analysis.

RESULTS

The prevalence rates of CKD_GFR, CKD_ACR, and CKD_Risk were 2.2%, 6.7%, and 8.1%, respectively. Compared with the normal body mass index (BMI; 18.5-22.9 kg/m²) group, men with BMI ≥ 25 kg/m² had 1.88 times greater risk of CKD_GFR in the adjusted model [95% confidence interval (CI), 1.26-2.80; P = 0.002]; BMI was not significantly associated with CKD_GFR in women. In contrast, both men and women with BMI ≥ 25 kg/m² had 1.58 and 1.40 times higher risk of CKD_ACR (95% CI, 1.21-2.07 and 1.08-1.81, respectively, both P < 0.01). Obese men and women had 1.65 and 1.38 times higher risk of CKD_Risk (95% CI, 1.29-2.12 and 1.09-1.75, respectively, both P < 0.01).

CONCLUSIONS

Obesity was significantly associated with an increased ACR-based CKD risk. Longitudinal studies are needed to investigate the role of overweight and obesity in the development and progression of CKD.

Influence of sex on hyperfiltration in patients with uncomplicated type 1 diabetes

The aim of this analysis was to examine sex-based differences in renal segmental resistances in healthy controls (HCs) and patients with type 1 diabetes (T1D). We hypothesized that hyperfiltration-an early hemodynamic abnormality associated with diabetic nephropathy-would disproportionately affect women with T1D, thereby attenuating protection against the development of renal complications. Glomerular hemodynamic parameters were evaluated in HC (n = 30) and in normotensive, normoalbuminuric patients with T1D and either baseline normofiltration [n = 36, T1D-N, glomerular filtration rate (GFR) 90-134 ml·min^-1·1.73 m²] or hyperfiltration (n = 32, T1D-H, GFR ≥ 135 ml·min^-1·1.73 m²) during euglycemic conditions (4-6 mmol/l). Gomez's equations were used to derive efferent (R_E) and afferent (R_A) arteriolar resistances, glomerular hydrostatic pressure (P_GLO) from inulin (GFR) and paraaminohippurate [effective renal plasma flow (ERPF)] clearances, plasma protein and estimated ultrafiltration coefficients (K_FG). Female patients with T1D with hyperfiltration (T1D-H) had higher R_E (1,985 ± 487 vs. 1,381 ± 296 dyne·sec^-1·cm^-5, P < 0.001) and filtration fraction (FF, 0.20 ± 0.047 vs. 0.16 ± 0.03 P < 0.05) and lower ERPF (876 ± 245 vs. 1,111 ± 298 134 ml·min^-1·1.73 m²P < 0.05) compared with male T1D-H patients. Overall, T1D-H patients had higher P_GLO and lower R_A vs. HC subjects, although there were no sex-based differences. In conclusion, female T1D-H patients had higher R_E and FF and lower ERPF than their male counterparts with no associated sex differences in R_A Prospective intervention studies should consider sex as a modifier of renal hemodynamic responses to renal protective therapies.

Association between Urine Albumin-to-Creatinine Ratio within the Normal Range and Incident Hypertension in Men and Women

PURPOSE

There have been few studies on gender difference in the impact of a urine albumin-to-creatinine ratio (UACR) within the normal range on the risk of hypertension. We evaluated whether the association between the UACR below the microalbuminuria range and the incident risk of hypertension is different between men and women.

MATERIALS AND METHODS

A total of 1173 individuals (442 men and 731 women) aged 40 to 70 years without hypertension was examined at baseline (2005-2008) and followed (2008-2011). We defined the UACR as the amount of albumin (mg/dL) divided by creatinine (g/dL) in randomly voided urine. The subjects were classified according to UACR tertile.

RESULTS

During an average of 2.6 years of follow-up, 57 men (12.9%) and 66 women (9.0%) developed hypertension. In multivariable-adjusted models, the odds ratio for new-onset hypertension comparing the highest and lowest tertiles of UACR was 1.83 [95% confidence interval (CI) 0.85-3.94] in men and 2.69 (95% CI 1.27-5.73) in women. In stratified analyses by menopausal status, higher tertiles of UACR were associated with an increased risk of incident hypertension in postmenopausal women.

CONCLUSION

Higher normal UACR levels were associated with an increased risk of incident hypertension in women. The UACR could have a clinical role in predicting the development of hypertension.

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.

Molecular cloning, characterization, tissue distribution and mRNA expression changes during the hibernation and reproductive periods of estrogen receptor alpha (ESR1) in Chinese alligator, Alligator sinensis

Chinese alligator, Alligator sinensis, is a critically endangered reptile species unique to China. Little is known about the mechanism of growth- and reproduction-related hormones gene expression in Chinese alligator. Estrogens play important roles in regulating multiple reproduction- and non-reproduction-related functions by binding to their corresponding receptors. Here, the full-length cDNA of estrogen receptor alpha (ERα/ESR1) was cloned and sequenced from Chinese alligator for the first time, which comprises 1764bp nucleotides and encodes a predicted protein of 587 amino acids. Phylogenetic analysis of ESR1 showed that crocodilians and turtles were the sister-group of birds. The results of real-time quantitative PCR indicated that the ESR1 mRNA was widely expressed in the brain and peripheral tissues. In the brain and pituitary gland, ESR1 was most highly transcribed in the cerebellum. But in other peripheral tissues, ESR1 mRNA expression level was the highest in the ovary. Compared with hibernation period, ESR1 mRNA expression levels were increased significantly in the reproductive period (P<0.05) in cerebellum, pituitary gland, liver, spleen, lung, kidney and ovary, while no significant change in other examined tissues (P>0.05). The ESR1 mRNA expression levels changes during the two periods of different tissues suggested that ESR1 might play an important role in mediation of estrogenic multiple reproductive effects in Chinese alligator. Furthermore, it was the first time to quantify ESR1 mRNA level in the brain of crocodilians, and the distribution and expression of ESR1 mRNA in the midbrain, cerebellum and medulla oblongata was also reported for the first time in reptiles.

Antioxidant diet and sex interact to regulate NOS isoform expression and glomerular mesangium proliferation in Zucker diabetic rat kidney

Oxidative stress contributes substantially to the pathophysiology of diabetic nephropathy (DN). Consumption of an antioxidant-fortified (AO) diet from an early age prevents or delays later development of DN in the Zucker rat female with type 2 diabetes. We hypothesize this is due to effects on mesangial matrix and renal nitric oxide synthase (NOS) distribution and to sex-specific differences in NOS responses in the diabetic kidney. Total glomerular tuft area (GTA) and PAS-positive tuft area (PTA), endothelial (e), neuronal (n) and inducible (i) NOS were quantified in males and females on AO or regular (REG) diet at 6 and 20 weeks of age. eNOS was observed in glomeruli and tubules. nNOS predominantly localized to tubular epithelium in both cortex and medulla. iNOS was expressed in proximal and distal tubules and collecting ducts. Sex, diabetes duration and AO diet affected the distribution of the three isoforms. GTA and PTA increased with duration of hyperglycemia and showed a negative correlation with renal levels of all NOS isoforms. AO diet in both genders was associated with less PAS-positive staining and less mesangial expansion than the REG diet, an early increase in cortical iNOS in males, and sex-specific changes in cortical eNOS at 20 weeks. These effects of AO diet may contribute to sex-specific preservation of renal function in females.

Sex differences in the association between obesity and albuminuria among Korean adults: a cross-sectional study using the Korea National Health and Nutrition Examination Survey data

Background

The association between obesity and albuminuria in the general population remains unclear. We aimed to identify the association between obesity and albuminuria as well as sex differences regarding the associations using several obesity indices, including waist circumference (WC), body mass index (BMI), and waist-to-height ratio (WHR).

Methods

This study included 3841 subjects (1730 males and 2111 females; age 20–80 years) who participated in the Fifth Korea National Health and Nutrition Examination Survey conducted in 2011. Subjects with hypertension, diabetes, renal failure, or a malignant tumor and those who were pregnant or menstruating were excluded. Albuminuria was defined as a urinary albumin-to-creatinine ratio ≥30 mg/g. Anthropometric parameters were categorized into sex-specific quartiles. Logistic regression models were used to assess the associations between each anthropometric parameter and albuminuria.

Results

All of the obesity indices of the fourth quartile group of females showed a twofold higher risk for albuminuria than the second quartile group, and it was persistently significant after adjusting for age, smoking, and physical activity. After further adjustment for high blood pressure and impaired fasting glucose and triglyceride levels, WC and BMI of the fourth quartile group of females still showed a significantly higher risk for albuminuria than the second quartile group (odds ratios 1.96 and 2.24; 95 % confidence intervals 1.03–3.74 and 1.15–4.37). None of the associations between albuminuria and the obesity indices were significant in males.

Conclusion

Higher WC and BMI were significantly associated with the risk of albuminuria among females, but not males.

Electronic supplementary material

The online version of this article (doi:10.1007/s10157-016-1238-z) contains supplementary material, which is available to authorized users.

Specific renal parenchymal-derived urinary extracellular vesicles identify age-associated structural changes in living donor kidneys

Non-invasive tests to identify age and early disease-associated pathology within the kidney are needed. Specific populations of urinary extracellular vesicles (EVs) could potentially be used for such a diagnostic test. Random urine samples were obtained from age- and sex-stratified living kidney donors before kidney donation. A biopsy of the donor kidney was obtained at the time of transplantation to identify nephron hypertrophy (larger glomerular volume, cortex per glomerulus and mean profile tubular area) and nephrosclerosis (% fibrosis, % glomerulosclerosis and arteriosclerosis). Renal parenchymal-derived EVs in cell-free urine were quantified by digital flow cytometry. The relationship between these EV populations and structural pathology on the kidney biopsy was assessed. Clinical characteristics of the kidney donors (n=138, age range: 20–70 years, 50% women) were within the normative range. Overall, urine from women contained more EVs than that from men. The number of exosomes, juxtaglomerular cells and podocyte marker–positive EVs decreased (p<0.05) with increasing age. There were fewer total EVs as well as EVs positive for mesangial cell, parietal cell, descending limb of Henle's loop (simple squamous epithelium), collecting tubule-intercalated cell and monocyte chemoattractant protein-1 markers (p<0.05) in persons with nephron hypertrophy. The number of EVs positive for intercellular adhesion molecule-1, juxtaglomerular cell, podocyte, parietal cell, proximal tubular epithelial cell, distal tubular epithelial cell and collecting duct cells were fewer (p<0.05) in persons with nephrosclerosis. EVs carrying markers of cells from the renal pelvis epithelium did not associate with any indices of nephron hypertrophy or nephrosclerosis. Therefore, specific populations of EVs derived from cells of the glomerulus and nephron associate with underlying kidney structural changes. Further validation of these findings in other cohorts is needed to determine their clinical utility.

Effect of Demographics on Excretion of Key Urinary Factors Related to Kidney Stone Risk

OBJECTIVE

To investigate the effect of demographics including age and sex on excretion of 4 key urinary factors (calcium [Ca], magnesium [Mg], oxalate and uric acid [UA]) related to kidney stone risk.

METHODS

Twenty-four-hour urine samples were collected from non-Hispanic white sibships in Rochester, MN. Height, weight, blood pressure, serum creatinine, and cystatin C were measured. Diet was assessed using the Viocare food frequency questionnaire. Effects of demographics and dietary elements on urinary excretions were evaluated in univariate, multivariate, and interaction models that included age, sex, and body mass index (BMI).

RESULTS

Samples were available from 709 individuals. In multivariate models, sex was a significant predictor of all 4 urinary factors, age was significant for all but UA excretion, and serum creatinine was significant only for Ca and Mg excretion (P <.05). BMI or weight positively correlated with Mg, oxalate, and UA excretion (P <.05). Use of a thiazide diuretic (lower) and dietary protein (higher) were associated with Ca excretion, whereas dietary Ca was associated with higher Mg excretion. Urinary UA excretion increased with animal protein intake and cystatin C estimated glomerular filtration rate (eGFR) and was lower with concurrent loop diuretic use. Significant interaction effects on urinary UA excretion were observed for loop diuretic use and sex, eGFR and sex, age and animal protein intake, and BMI and eGFR (P <.05).

CONCLUSION

Age and sex influence excretion of key urinary factors related to kidney stone risk and should be taken into account when evaluating kidney stone patients.

Preventive role of estradiol on kidney injury induced by renal ischemia-reperfusion in male and female rats

Background:

Renal ischemia-reperfusion (RIR) is the main cause of renal failure. The incidence of RIR injury seems to be gender-related due to female sex hormone; estrogen. This study was designed to investigate the protective role of estrogen against RIR injury in male and ovariectomized female rats.

Methods:

Thirty-nine Wistar rats were used in this study as male and ovariectomized female rats in the sham-operated, RIR, and estradiol-treated plus RIR groups. The RIR was induced by clamping the renal vessels for 45 min and then 24 h of reperfusion. All animals finally were sacrificed for the measurements.

Results:

The serum levels of creatinine and blood urea nitrogen and kidney tissue damage score significantly increased in both male and female RIR rats (P < 0.05). Estradiol however significantly attenuated theses parameters (P < 0.05) toward normal levels in female (P < 0.05), but not in male rats. Kidney weight increased in both genders and estradiol intensified it in the male rats (P < 0.05). Uterus weight was increased by estradiol in female rats (P < 0.05) and testis weight did not alter in male rats.

Conclusions:

Estradiol demonstrated a protective role against RIR injury in female rats; however, estradiol as an antioxidant could not protect the male kidney from RIR injury.

Estrogen receptor alpha expression and liver fibrosis in chronic hepatitis C virus genotype 1b: a clinicopathological study

BACKGROUND

Hepatic damage due to chronic hepatitis C virus (HCV) genotype 1b infection varies widely.

OBJECTIVES

We aimed to investigate whether estrogen receptor alpha (ERα) plays a role in liver fibrosis in patients infected with HCV genotype 1b.

PATIENTS AND METHODS

All the consecutive patients who received the same standard treatment protocol for HCV genotype 1b were subdivided into two subgroups according to their fibrosis scores as fibrotic stages < 2 in mild fibrosis group and fibrotic stages ≥ 2 in advanced fibrosis group, depending on the presence of septal fibrosis. ERα was stained in liver biopsy specimens. Demographics and clinical properties were compared between the groups. Multivariate logistic regression analysis was performed to predict advanced fibrosis.

RESULTS

There were 66 patients in the mild fibrosis group and 24 in the advanced fibrosis group. Among the mild and advanced fibrosis groups, 65.1% and 50%were female, respectively (P = 0.19). There was an inverse correlation between ERα and fibrotic stage (r: -0.413; P < 0.001). Age, platelet counts, neutrophil counts, Alanine aminotransferase (ALT), Aspartate aminotransferase (AST), Gamma glutamyl transferase (GGT) and ERα were statistically significant in the univariate analysis. In multivariate logistic regression analyses, ERα expression continued to be an independent predicting factor of liver fibrosis in patients infected with chronic HCV genotype 1b (OR: 0.10; 95% CI: 0.018-0.586; P < 0.001).

CONCLUSIONS

ERα expression in liver was inversely correlated with liver fibrosis among patients infected with chronic HCV genotype 1b.

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.

Role of G protein-coupled estrogen receptor 1 in modulating transforming growth factor-β stimulated mesangial cell extracellular matrix synthesis and migration

Estrogen has been demonstrated to exert beneficial effects on kidney; however, the role of G protein-coupled estrogen receptor 1 (GPER) is still uncertain. In the present study, we investigated the effect of 17β-estradiol and GPER agonist Fulvestrant on extracellular matrix production under transforming growth factor-β1 (TGF-β1) stimulation in human and rat mesangial cells. As a result, 17β-estradiol and Fulvestrant inhibit TGF-β1-induced type IV collagen and fibronectin expression in a dose-dependent manner, by suppressing acute Smad2/3 phosphorylation and Smad4 complex formation. Furthermore, estrogen and Fulvestrant also down-regulate Smad signaling by promoting ubiquitin/proteasome-dependent Smad2 degradation. These effects could be abrogated by receptor antagonist G-15 or GPER gene knockdown. GPER is also required for estrogen and Fulvestrant to regulate mesangial cell migration in response to TGF-β1. To conclude, GPER is crucial in modulating glomerular mesangial cell function including extracellular matrix production and migration.

Associations of smoking with alterations in renal hemodynamics may depend on sex--investigations in potential kidney donors

BACKGROUND/AIMS

Cigarette smoking is a risk factor for renal damage, but little is known about subclinical effects of smoking on renal hemodynamics and parameters of renal function in humans. We examined the associations of smoking with systemic and renal hemodynamics and renal function parameters in healthy individuals.

METHODS

Data from 196 potential living kidney donors were analysed retrospectively. Mean arterial blood pressure (MAP), effective renal plasma flow (ERPF) and creatinine clearance had been measured. We additionally calculated parameters of renal hemodynamics. Data were analyzed for the effects of smoking and sex dependent on age and MAP.

RESULTS

Systemic and renal hemodynamic parameters did not differ between smokers and non-smokers. In non-smokers of both sexes MAP was negatively correlated with ERPF, and higher MAP was associated with increased renal vascular resistance and with afferent arteriolar resistance, with glomerular pressure (PG) remaining constant. However, in male, but not in female smokers, ERPF and PG increased with MAP. A correlation of age with a steeper decline in ERPF in male smokers was lost in multiple regression analysis.

CONCLUSIONS

As compared to women, smoking men may exhibit an increased glomerular hydrostatic pressure, which is a known promoter of kidney damage.

Sugar, sex, and TGF-β in diabetic nephropathy

TGF-β is well known to play a critical role in diabetic kidney disease, and ongoing clinical studies are testing the potential therapeutic promise of inhibiting TGF-β production and action. An aspect of TGF-β action that has not received much attention is its potential role in explaining sex-related proclivity for kidney disease. In this review, we discuss recent studies linking TGF-β signaling to sex-related effects in diabetic kidney disease and suggest targets for future studies.

Sexual dimorphism: the aging kidney, involvement of nitric oxide deficiency, and angiotensin II overactivity

Females develop less age-dependent loss of renal function, which may be in part due to cardiorenal protective effects of estrogens. The impact of androgen level on cardiovascular-renal health is controversial. Estrogen acts through multiple mechanisms, sometimes beneficial, sometimes damaging, which makes it difficult to predict the effect of hormone replacement therapy (HRT) in an aging population. Nitric oxide (NO) deficiency occurs in aging and contributes to age-dependent cardiovascular risk and kidney damage. The increased oxidative stress of aging has effects at multiple sites in the NO biosynthetic pathway to lower NO production/action. Loss of NO together with activated angiotensin promotes some of the decrements in cardiovascular-renal function seen with age, which may be related to actions of the sex steroids.

Early life stress induces renal dysfunction in adult male rats but not female rats

Maternal separation (MatSep) is a model of behavioral stress during early life. We reported that MatSep exacerbates ANG II-induced hypertension in adult male rats. The aims of this study were to determine whether exposure to MatSep in female rats sensitizes blood pressure to ANG II infusion similar to male MatSep rats and to elucidate renal mechanisms involved in the response in MatSep rats. Wistar Kyoto (WKY) pups were exposed to MatSep 3 h/day from days 2 to 14, while control rats remained with their mothers. ANG II-induced mean arterial pressure (MAP; telemetry) was enhanced in female MatSep rats compared with control female rats but delayed compared with male MatSep rats. Creatinine clearance (Ccr) was reduced in male MatSep rats compared with control rats at baseline and after ANG II infusion. ANG II infusion significantly increased T cells in the renal cortex and greater histological damage in the interstitial arteries of male MatSep rats compared with control male rats. Plasma testosterone was greater and estradiol was lower in male MatSep rats compared with control rats with ANG II infusion. ANG II infusion failed to increase blood pressure in orchidectomized male MatSep and control rats. Female MatSep and control rats had similar Ccr, histological renal analysis, and sex hormones at baseline and after ANG II infusion. These data indicate that during ANG II-induced hypertension, MatSep sensitizes the renal phenotype in male but not female rats.

Orchiectomy attenuates kidney fibrosis after ureteral obstruction by reduction of oxidative stress in mice

BACKGROUND/AIMS

Men are generally more prone to chronic kidney disease and progression to end-stage renal disease than women. However, the underlying mechanisms remain unclear. In this study, we investigated the role of reactive oxygen species and testosterone in the progression of renal fibrosis in mice with unilateral ureteral obstruction (UUO).

METHODS

Mice were subjected to either orchiectomy or sham operation 14 days before either UUO or sham surgery. Harvesting of the kidney was performed 7 days after the UUO surgery to measure the production of reactive oxygen species and expression of antioxidants such as catalase, copper-zinc superoxide dismutase, and manganese superoxide dismutase, as well as fibrosis markers including α-smooth muscle actin (α-SMA) and collagen.

RESULTS

UUO resulted in increased expression of α-SMA and collagen deposition in the kidneys of both female and male mice. These increases were significantly greater in males than females. Orchiectomy significantly reduced increases in α-SMA expression and collagen deposition when compared with intact male. UUO increased the production of hydrogen peroxide and lipid peroxidation along with the decreases in expression of manganese superoxide dismutase, copper-zinc superoxide dismutase, and catalase. These changes induced by UUO were significantly attenuated by orchiectomy.

CONCLUSION

Males are more susceptible to UUO-induced kidney fibrosis compared with females, and the higher susceptibility of males is obviated by orchiectomy along with reduction in oxidative stress.

Antifibrotic effect of tamoxifen in a model of progressive renal disease

Tamoxifen, a selective estrogen receptor modulator, has antifibrotic properties; however, whether it can attenuate renal fibrosis is unknown. In this study, we tested the effects of tamoxifen in a model of hypertensive nephrosclerosis (chronic inhibition of nitric oxide synthesis with L-NAME). After 30 days, treated rats had significantly lower levels of albuminuria as well as lower histologic scores for glomerulosclerosis and interstitial fibrosis than untreated controls. Tamoxifen was renoprotective despite having no effect on the sustained, severe hypertension induced by L-NAME. Tamoxifen prevented the accumulation of extracellular matrix by decreasing the expression of collagen I, collagen III, and fibronectin mRNA and protein. These renoprotective effects associated with inhibition of TGF-β1 and plasminogen activator inhibitor-1, and with a significant reduction in α-smooth muscle actin-positive cells in the renal interstitium. Furthermore, tamoxifen abrogated IL-1β- and angiotensin-II-induced proliferation of fibroblasts from both kidney explants and from the NRK-49F cell line. Tamoxifen also inhibited the expression of extracellular matrix components and the production and release of TGF-β1 into the supernatant of these cells. In summary, tamoxifen exhibits antifibrotic effects in the L-NAME model of hypertensive nephrosclerosis, likely through the inhibition of TGF-β1, suggesting that it may have therapeutic use in CKD treatment.

Sex differences in the relationship between leukocyte count and chronic kidney disease: the 2007 Korean National Health and Nutrition Examination Survey

BACKGROUND

Chronic kidney disease (CKD) has emerged as an independent predictor for cardiovascular disease (CVD), which is now regarded as an inflammatory disease. This study aimed to determine the association of CKD with white blood cell (WBC) count as a marker of systemic inflammation.

METHODS

We examined the association of WBC count with CKD in 2825 Korean adults (1155 men, 1670 women) in the 2007 Korean National Health and Nutrition Examination Survey (KNHANES). CKD was defined as either proteinuria or a glomerular filtration rate (GFR) <60 mL/min/1.73 m(2). The odds ratios (ORs) for CKD were calculated using multivariate logistic regression analysis after adjusting for confounding variables across gender-specific WBC count quartiles.

RESULTS

The proportion of CKD increased with increasing WBC quartiles, from 9.7% in the lowest quartile to 20.7% in the highest quartile for women. In multivariate logistic regression analysis, the corresponding odds ratios (95% confidence intervals [CIs]) for a CKD across WBC count quartiles among women were 1.00, 1.45 (0.91-2.31), 1.65 (1.03-2.63), and 2.11 (1.33-3.35), after adjusting for age, body mass index (BMI), systolic blood pressure, fasting plasma glucose, smoking status, current drinking high-density lipoprotein cholesterol (HDL-C), and triglyceride. In contrast, compared with women, men appeared to have no significant results of a relationship between WBC quartiles and CKD.

CONCLUSIONS

Our study shows a significant association between WBC count and the risk for CKD in women. Accordingly, potential health benefits of early detection of a higher level of WBC count may be useful for CKD risk assessment in women.

Raloxifene, a selective estrogen receptor modulator, is renoprotective: a post-hoc analysis

Estrogens have a protective effect on kidney fibrosis in several animal models. Here, we tested the effect of raloxifene, an estrogen receptor modulator, on the change in serum creatinine or estimated glomerular filtration rate (eGFR) and incident kidney-related adverse events. We performed a post-hoc analysis of the multiple outcomes of raloxifene evaluation trial, a double-masked, placebo-controlled randomized clinical trial encompassing 7705 post-menopausal women (aged 31-80 years) with osteoporosis. Participants were randomized to either of two doses of raloxifene, 60 or 120 mg/day, or placebo. Serum creatinine was measured at a central laboratory at baseline and annually. Adverse events were assessed every 6 months and uniformly categorized. Compared with those in the placebo group, participants on raloxifene had a slower yearly rate of increase in creatinine (significant at the low dose) and a significantly slower yearly rate of decrease in eGFR for both doses over 3 years of follow-up. Raloxifene was associated with significantly fewer kidney-related adverse events compared with placebo. Thus, treatment with raloxifene was safe and renoprotective. Clinical trials of raloxifene in post-menopausal women with kidney disease designed to look at kidney outcomes are needed to confirm these findings.

Sexual dimorphism, the aging kidney, and involvement of nitric oxide deficiency

Females develop less age-dependent loss of renal function, in part because of cardiorenal protective effects of estrogens. The low androgen level in women also may be protective, although the animal and clinical data are controversial. Both estrogen and androgens act through multiple mechanisms, sometimes beneficial, sometimes damaging, which makes it difficult to predict the impact of hormone replacement therapy in an aging population. Nitric oxide (NO) deficiency contributes to age-dependent cardiovascular risk and kidney damage in animal models. The increased oxidative stress of aging impacts at multiple sites in the NO biosynthetic pathway to decrease NO production/action. Endothelial dysfunction develops with aging and is delayed in women, in association with a delayed increase in asymmetric dimethylarginine. Animal data suggest that the aging kidney develops NO deficiency because of changes in the neuronal NO synthase. Relative preservation of NO production in females contributes to the better cardiovascular and renal responses to aging.

17 beta-estradiol and tamoxifen upregulate estrogen receptor beta expression and control podocyte signaling pathways in a model of type 2 diabetes

Diabetic nephropathy remains one of the most important causes of end-stage renal disease. This is particularly true for women from racial/ethnic minorities. Although administration of 17beta-estradiol to diabetic animals has been shown to reduce extracellular matrix deposition in glomeruli and mesangial cells, effects on podocytes are lacking. Given that podocyte injury has been implicated as a factor leading to the progression of proteinuria and diabetic nephropathy, we treated db/db mice, a model of type 2 diabetic glomerulosclerosis, with 17beta-estradiol or tamoxifen to determine whether these treatments reduce podocyte injury and decrease glomerulosclerosis. We found that albumin excretion, glomerular volume, and extracellular matrix accumulation were decreased in these mice compared to placebo treatment. Podocytes isolated from all treatment groups were immortalized and these cell lines were found to express the podocyte markers WT-1, nephrin, and the TRPC6 cation channel. Tamoxifen and 17beta-estradiol treatment decreased podocyte transforming growth factor-beta mRNA expression but increased that of the estrogen receptor subtype beta protein. 17beta-estradiol, but not tamoxifen, treatment decreased extracellular-regulated kinase phosphorylation. These data, combined with improved albumin excretion, reduced glomerular size, and decreased matrix accumulation, suggest that both 17beta-estradiol and tamoxifen may protect podocytes against injury and therefore ameliorate diabetic nephropathy.

Rat mesangial cells exhibit sex-specific profibrotic and proinflammatory phenotypes

BACKGROUND

Chronic renal disease progresses more rapidly in males compared to females. This study investigated whether there were any inherent differences between male and female mesangial cells that could contribute to this phenomenon and whether these differences could be modulated by sex hormones.

METHODS

Experiments were carried out on cultured mesangial cells derived from adult male and female Wistar rat kidneys. Fibronectin, TNFalpha and IL-1beta levels were measured in control and macrophage-conditioned medium (MCM)-injured cells in the presence and absence of 17beta estradiol or testosterone.

RESULTS

Male mesangial cells expressed higher baseline fibronectin levels compared to female cells. Similarly, basal levels of the proinflammatory cytokines TNFalpha and IL-1beta were higher in male cells. Fibronectin and IL-1beta levels were enhanced proportionately between the sexes in response to MCM stimulation, whilst the increase in TNFalpha levels was greater in MCM-stimulated female cells. Treatment with 10(-8) M estradiol down-regulated baseline fibronectin levels in female mesangial cells but had no effect on basal levels in male cells. Estradiol had no effect on MCM-stimulated fibronectin levels in female mesangial cells but further increased stimulated levels in male cells. Testosterone had no effect on basal fibronectin levels of either sex but further enhanced MCM-stimulated fibronectin levels in mesangial cells of both sexes. Sex hormone treatment had no effect on cytokine levels in male mesangial cells. However, in female cells estradiol decreased TNFalpha levels and increased IL-1beta levels, while testosterone increased the levels of both cytokines.

CONCLUSION

These data would suggest that male mesangial cells inherently exhibit greater profibrotic and proinflammatory characteristics than female cells. The inherent gender phenotypes are further modulated by sex hormones. This sexual dimorphism in mesangial cells may play a contributory role in the faster rate of progression to end-stage renal disease in males.

Sexual dimorphism of the aging kidney: role of nitric oxide deficiency

GFR falls with aging in humans and rats due to renal vasoconstriction and structural damage. The rate of deterioration is influenced by race/genetic background, environment, and sex, with females protected. Part of the female advantage relates to protective effects of estrogens. There is little information on impact of aging on the distribution/cardiovascular actions of the estrogen receptor subtypes. In rats, androgens may contribute to injury, but in men, high testosterone levels predict cardiovascular health. In women, the association is controversial. Nitric oxide deficiency contributes to the hypertension and renal dysfunction of aging, which may be delayed in the female.

Clinicopathological study of nonalcoholic fatty liver disease in Japan: the risk factors for fibrosis

BACKGROUND/AIMS

We evaluated patients with nonalcoholic fatty liver disease (NAFLD) and compared the clinical and pathological features to identify the risk factors for NAFLD with severe fibrosis.

METHODS

One hundred and eighty-two patients with biopsy-confirmed NAFLD from various medical centres were recruited into this study.

RESULTS

The variables that were significantly associated with severe steatosis were male gender (mild:severe=36%:53%, P=0.02), younger age (mild:severe=57%:82%, P>0.001) and absence of type 2 diabetes (mild:severe=43%:71%, P>0.001). There was no significant difference in the degree of inflammation among the clinical groups. The variables that were significantly associated with severe fibrosis were female gender (mild:severe=54%:84%, P=0.002), older age (> or = 60 years old) (mild:severe=29%:53%, P=0.020), type 2 diabetes (mild:severe=42%:71%, P=0.020) and hypertension (mild:severe=24%:53%, P=0.002). Although there were more obese patients in the group with severe fibrosis, the association was not statistically significant (mild:severe=67%:78%, P=0.229). The prevalence of high serum triglyceride levels was similar between the two groups. The N (Nippon) score (total number of risk factor) could significantly predict severe fibrosis in NAFLD patients (1.48 +/- 1.14 vs. 2.66 +/- 0.94, P<0.001).

CONCLUSIONS

The N score can be used to predict severe fibrosis in cases of NAFLD.