Gender differences in the risk for chronic renal allograft failure

Sex/Gender Disparities in Preemptive Referrals for Kidney Transplantation

Introduction

Sex/gender inequities persist in access to kidney transplantation. Whether differences in preemptive referral (i.e., referral before dialysis start) explain this inequity remains unknown.

Methods

All adults (aged 18-79 years; N = 44,204) initiating kidney replacement therapy (KRT; dialysis or transplant) in Georgia (GA), North Carolina (NC), or South Carolina (SC) between 2015 and 2019 were identified from the United States Renal Data System (USRDS). Individuals were linked to the Early Steps to Kidney Transplant Access Registry (E-STAR) to obtain data on preemptive referral and followed-up with through November 13, 2020, for outcomes of waitlisting and living donor transplant. Logistic regression assessed the association between sex/gender and likelihood of preemptive referral among all KRT patients. Cox-proportional hazards assessed the association between sex/gender and waitlisting or living donor among preemptively referred patients.

Results

Overall, men and women were similarly likely to be preemptively referred (odds ratio [OR]: 0.99 [0.95-1.04]). Preemptively referred women (vs. men) were, on average, younger and with fewer comorbidities. There were no sex/gender differences in waitlisting once patients were preemptively referred (hazard ratio [HR]: 0.97 [0.91-1.03]); however, women (vs. men) who were preemptively referred remained 25% (HR: 0.75 [0.66-0.86]) less likely to receive a living donor transplant.

Conclusion

In the Southeast US, men and women initiating KRT are similarly likely to be preemptively referred for a kidney transplant, and this appears, at least in part, to mitigate known sex/gender inequities in access to waitlisting, but not living donor transplant. Despite this, preemptively referred women, on average, had a more favorable medical profile relative to preemptively referred men.

The combinatorial effect of age and biological sex on alloimmunity and transplantation outcome

Both age and biological sex affect transplantation outcomes. We have recently shown in a large volume clinical analysis utilizing the SRTR data that graft survival is inferior in young female kidney transplant recipients. In this multi-factorial analysis, older female recipients presented with a trend towards improved transplant outcomes compared to both young female recipients and male recipients of any age. Those data supported by reports of those of others suggest that sex and age impact alloimmune responses both, individually and synergistically. Biological sex and hormone levels change throughout a lifetime with recognized effects on longevity in addition to an impact on the development and course of several disease preconditions. Detailed mechanisms of those sex and age-specific aspects have thus far been studied outside of transplantation. Effects on alloimmunity are largely unknown. Moreover, the combinatorial impact that both, biological sex and age have on transplant outcomes is not understood. Here, we summarize available data that analyze how age in combination with biological sex may shape alloimmune responses and affect transplant outcomes.

Sex/Gender-Based Disparities in Early Transplant Access by Attributed Cause of Kidney Disease-Evidence from a Multiregional Cohort in the Southeast United States

Introduction

We examined sex/gender disparities across the continuum of transplant care by attributed cause of end-stage kidney disease (ESKD).

Methods

All adults (18-79 years; N = 43,548) with new-onset ESKD in Georgia, North Carolina, or South Carolina between 2015 and 2019 were identified from the United States Renal Data System (USRDS). Individuals were linked to the Early Steps to Transplant Access Registry (E-STAR) to obtain data on referral and evaluation. Waitlisting data was ascertained from USRDS. Using a Cox-proportional hazards model, with follow-up through 2020, we assessed the association between sex/gender and referral within 12 months (among all incident dialysis patients), evaluation start within 6 months (among referred patients), and waitlisting (among all evaluated patients) by attributed cause of ESKD (type 1 diabetes mellitus, type 2 diabetes mellitus, hypertension, glomerulonephritis, cystic disease, and other).

Results

Overall, women (vs. men) with type 2 diabetes-attributed ESKD were 13% (crude hazard ratio [HR]: 0.87 [0.83-0.91]), 14% (crude HR: 0.86 [0.81-0.91]), and 14% (crude HR: 0.86 [0.78-0.94]) less likely to be referred, evaluated, and waitlisted, respectively. Women (vs. men) with hypertension-attributed ESKD were 14% (crude HR: 0.86 [0.82-0.90]) and 8% (crude HR: 0.92 [0.87-0.98]) less likely to be referred and evaluated, respectively, but similarly likely to be waitlisted once evaluated (crude HR: 1.06 [0.97-1.15]). For all other attributed causes of ESKD, there was no sex/gender disparity in referral, evaluation, or waitlisting rates.

Conclusion

In the Southeast United States, sex/gender disparities in early access to kidney transplantation are specific to people with ESKD attributed to type 2 diabetes and hypertension.

Excess mortality after kidney transplantation: does sex matter?

Understanding sex differences in graft outcomes within the course of kidney transplantation is needed to unravel factors leading to the observed disparities and further improve patient management. In this issue, Vinson et al. presented a relative survival analysis comparing the excess risk of mortality in female and male recipients after kidney transplantation. This commentary discusses the major findings but also the challenges of the use of registry data to conduct large-scale analyses.

Prediction of Renal Function 1 Year After Transplantation Using Machine Learning Methods Based on Ultrasound Radiomics Combined With Clinical and Imaging Features

Kidney transplantation is the most effective treatment for advanced chronic kidney disease (CKD). If the prognosis of transplantation can be predicted early after transplantation, it might improve the long-term survival of patients with transplanted kidneys. Currently, studies on the assessment and prediction of renal function by radiomics are limited. Therefore, the present study aimed to explore the value of ultrasound (US)-based imaging and radiomics features, combined with clinical features to develop and validate the models for predicting transplanted kidney function after 1 year (TKF-1Y) using different machine learning algorithms. A total of 189 patients were included and classified into the abnormal TKF-1Y group, and the normal TKF-1Y group based on their estimated glomerular filtration rate (eGFR) levels 1 year after transplantation. The radiomics features were derived from the US images of each case. Three machine learning methods were employed to establish different models for predicting TKF-1Y using selected clinical and US imaging as well as radiomics features from the training set. Two US imaging, four clinical, and six radiomics features were selected. Then, the clinical (including clinical and US image features), radiomics, and combined models were developed. The area under the curves (AUCs) of the models was 0.62 to 0.82 within the test set. Combined models showed statistically higher AUCs than the radiomics models (all p-values <.05). The prediction performance of different models was not significantly affected by the different machine learning algorithms (all p-values >.05). In conclusion, US imaging features combined with clinical features could predict TKF-1Y and yield an incremental value over radiomics features. A model integrating all available features may further improve the predictive efficacy. Different machine learning algorithms may not have a significant impact on the predictive performance of the model.

Sex and gender disparity in kidney transplantation: Historical and future perspectives

Sex and gender disparity exist in various stages of kidney transplantation. Females were found to be less likely to be referred for kidney transplant, complete pre-transplant evaluation, be placed on the waitlist, and receive a kidney transplant compared to their male counterparts. Interestingly, females comprise the majority of living kidney donors. This review explores the biological and psychosocial factors that contribute to sex and gender disparity in kidney transplantation and proposes ways to address the disparity.

Entering the Third Decade After Kidney Transplantation: Excellent Graft Function Refers to Superior Graft but Not Patient Survival

Kidney transplant recipients (KTRs) with ultralong-term survival represent a growing, yet insufficiently studied patient cohort. In this single-center retrospective study, we analyzed 248 ultralong-term survivors (≥20 years). KTRs were classified into those with superior graft function (defined as eGFR ≥45 ml/min + proteinuria ≤300 mg/day + eGFR-slope ≤ 2 ml/min/1.73 m2/year) and inferior graft function regarding the risk of CKD progression. 20 years post-transplant, median eGFR was 54 ml/min (11-114), proteinuria 200 mg/24 h (0-7,620), eGFR decline 0.45 ml/min/1.73 m2/year (11.7 6.5) and DSA had been detected in 19.7% of KTRs. We identified 96 KTRs (38.7%) with superior (group 1) and 152 KTRs (61.3%) with inferior graft function (group 2). Donation after cardiac death, female sex, glomerulonephritis as primary disease, and early TCMR were independently associated with inferior graft function. Graft survival was significantly better in group 1 compared to group 2 (LogRank, p < 0.001). Besides group affiliation (HR 20.515, p = 0.003), multivariable analysis identified DSA development (HR 3.081, p = 0.023) and donor age (HR 1.032, p = 0.024) as independent factors. Interestingly, there was no significant difference in patient survival (LogRank, p = 0.350). In ultralong-term survivors, excellent graft function refers to superior graft survival but does not extend ultimate patient survival. DSA-formation should be taken seriously even in the ultralong-term.

Gender Disparities in Kidney Transplantation Referral Vary by Age and Race: A Multiregional Cohort Study in the Southeast United States

Introduction

Men (vs. women) are more likely to be waitlisted or receive a kidney transplant. Whether gender disparities exist in earlier transplant steps (i.e., referral) and whether age, race, or obesity factors play a role are unknown.

Methods

Adults (18-80 years; N = 45,015) initiating dialysis in Georgia (GA), North Carolina (NC), or South Carolina (SC) (2012-2016) from the United States Renal Data System were linked to the Early Transplant Access Registry, with follow-up to December 2017. Using a mixed-effects logistic regression model adjusted for several patient characteristics, we assessed the association between gender and referral within 12 months, including interaction terms for age, race/ethnicity, and obesity.

Results

Overall, 37.0% and 41.5% of women and men, respectively, were referred within 12 months. In fully adjusted models, women (vs. men) were 14% less likely to be referred (odds ratio [OR]: 0.86; 95% CI: 0.82-0.90). Women (vs. men) aged 45 to 64 years and 65 to 80 years were 0.93 (0.87-0.99) and 0.72 (0.66-0.77) less likely to be referred, respectively. Women (vs. men) of non-Hispanic White and non-Hispanic Black race were 0.76 (0.71-0.82) and 0.93 (0.88-0.99) less likely to be referred, respectively. For other race (Hispanic, other) and age (18-44 years) subgroups, and all obesity subgroups, no gender differences in referral rates were observed.

Conclusion

In the Southeast, women are less likely to be referred for a transplant, and this disparity is specific to older non-Hispanic Black and White women. These findings have important implications for known gender disparities in upstream (i.e., waitlisting) transplant steps and in the design of interventions to reduce gender disparities in transplant.

The Impact of Inflammation on the Immune Responses to Transplantation: Tolerance or Rejection?

Transplantation (Tx) remains the optimal therapy for end-stage disease (ESD) of various solid organs. Although alloimmune events remain the leading cause of long-term allograft loss, many patients develop innate and adaptive immune responses leading to graft tolerance. The focus of this review is to provide an overview of selected aspects of the effects of inflammation on this delicate balance following solid organ transplantation. Initially, we discuss the inflammatory mediators detectable in an ESD patient. Then, the specific inflammatory mediators found post-Tx are elucidated. We examine the reciprocal relationship between donor-derived passenger leukocytes (PLs) and those of the recipient, with additional emphasis on extracellular vesicles, specifically exosomes, and we examine their role in determining the balance between tolerance and rejection. The concept of recipient antigen-presenting cell "cross-dressing" by donor exosomes is detailed. Immunological consequences of the changes undergone by cell surface antigens, including HLA molecules in donor and host immune cells activated by proinflammatory cytokines, are examined. Inflammation-mediated donor endothelial cell (EC) activation is discussed along with the effect of donor-recipient EC chimerism. Finally, as an example of a specific inflammatory mediator, a detailed analysis is provided on the dynamic role of Interleukin-6 (IL-6) and its receptor post-Tx, especially given the potential for therapeutic interdiction of this axis with monoclonal antibodies. We aim to provide a holistic as well as a reductionist perspective of the inflammation-impacted immune events that precede and follow Tx. The objective is to differentiate tolerogenic inflammation from that enhancing rejection, for potential therapeutic modifications. (Words 247).

Renal Outcomes After Simultaneous Liver-Kidney Transplantation: Results from the US Multicenter Simultaneous Liver-Kidney Transplantation Consortium

Simultaneous liver-kidney transplantation (SLKT) is increasingly common in the United States. However, little is known about the renal-related outcomes following SLKT, which are essential to maximize the health of these allografts. We examined the factors impacting renal function following SLKT. This is an observational multicenter cohort study from the US Multicenter SLKT Consortium consisting of recipients of SLKT aged ≥18 years of transplantations performed between February 2002 and June 2017 at 6 large US centers in 6 different United Network for Organ Sharing regions. The primary outcome was incident post-SLKT stage 4-5 chronic kidney disease (CKD) defined as <30 mL/minute/1.73 m² or listing for kidney transplant. The median age of the recipients (n = 570) was 58 years (interquartile range, 51-64 years), and 37% were women, 76% were White, 33% had hepatitis C virus infection, 20% had nonalcoholic steatohepatitis (NASH), and 23% had alcohol-related liver disease; 68% developed ≥ stage 3 CKD at the end of follow-up. The 1-year, 3-year, and 5-year incidence rates of post-SLKT stage 4-5 CKD were 10%, 12%, and 16%, respectively. Pre-SLKT diabetes mellitus (hazard ratio [HR], 1.45; 95% CI, 1.00-2.15), NASH (HR, 1.58; 95% CI, 1.01-2.45), and delayed kidney graft function (HR, 1.72; 95% CI, 1.10-2.71) were the recipient factors independently associated with high risk, whereas the use of tacrolimus (HR, 0.44; 95% CI, 0.22-0.89) reduced the risk. Women (β = -6.22 ± 2.16 mL/minute/1.73 m² ; P = 0.004), NASH (β = -7.27 ± 3.27 mL/minute/1.73 m² ; P = 0.027), and delayed kidney graft function (β = -7.25 ± 2.26 mL/minute/1.73 m² ; P = 0.007) were independently associated with low estimated glomerular filtration rate at last follow-up. Stage 4-5 CKD is common after SLKT. There remains an unmet need for personalized renal protective strategies, specifically stratified by sex, diabetes mellitus, and liver disease, to preserve renal function among SLKT recipients.

Sex Differences in Renal Function: Participation of Gonadal Hormones and Prolactin

Kidney pathophysiology is influenced by gender. Evidence suggests that kidney damage is more severe in males than in females and that sexual hormones contribute to this. Elevated prolactin concentration is common in renal impairment patients and is associated with an unfavorable prognosis. However, PRL is involved in the osmoregulatory process and promotes endothelial proliferation, dilatation, and permeability in blood vessels. Several proteinases cleavage its structure, forming vasoinhibins. These fragments have antagonistic PRL effects on endothelium and might be associated with renal endothelial dysfunction, but its role in the kidneys has not been enough investigated. Therefore, the purpose of this review is to describe the influence of sexual dimorphism and gonadal hormones on kidney damage, emphasizing the role of the hormone prolactin and its cleavage products, the vasoinhibins.

Recipient Sex Differences in Kidney Graft Survival Are Influenced by Donor Sex and Recipient Age

OBJECTIVES

An age-dependent interaction has been described for the effect of donor-recipient sex mismatch on outcomes after kidney transplant in the United States. However, this has not been verified or tested in a different cohort from another country.

MATERIALS AND METHODS

Data of 25 140 deceased donor kidney transplant recipients (2000-2016) were retro-spectively analyzed at a population-cohort level using the United Kingdom transplant registry. Within sub-groups of donor sex, associations between recipient sex and death-censored graft survival were assessed for the cohort as a whole and within recipient age subgroups.

RESULTS

No differences in graft survival were detected between female versus male recipients of male donor kidneys (adjusted hazard ratio: 1.05; P = .227). However, a significant interaction between the age and sex of recipients was identified (P = .007). Female recipients aged 25 to 44 years had significantly shorter graft survival than male recipients (adjusted hazard ratio: 1.27; P = .003), but this effect was reversed in recipients who were 45 years or older (adjusted hazard ratio: 0.94; P = .258), where there was a nonsignificant tendency for longer graft survival in females. No such effect was observed in the subgroup of female donor transplants, with no significant difference between female versus male recipients overall (adjusted hazard ratio: 1.02; P = .638) and no significant interaction with age (P = .470).

CONCLUSIONS

Graft survival is influenced by the combination of recipient age and sex in recipients of male donor kidneys only. This work demonstrates findings broadly similar to published reports but presents differences in observed effect sizes among certain subgroups. Our research suggests further work is warranted to explore personalized approaches to age- and sex-adapted immunosuppression.

Sex-Associated Differences in Cytomegalovirus Prevention: Prophylactic Strategy is Potentially Associated With a Strong Kidney Function Impairment in Female Renal Transplant Patients

Post-transplantation cytomegalovirus (CMV) syndrome can be prevented using the antiviral drug (val)ganciclovir. (Val)ganciclovir is typically administered following a prophylactic or a pre-emptive strategy. The prophylactic strategy entails early universal administration, the pre-emptive strategy, early treatment in case of infection. However, it is not clear which strategy is superior with respect to transplantation outcome; sex-specific effects of these prevention strategies are not known. We have retrospectively analyzed 540 patients from the multi-centre Harmony study along eight pre-defined visits: 308 were treated according to a prophylactic, 232 according to a pre-emptive strategy. As expected, we observed an association of prophylactic strategy with lower incidence of CMV syndrome, delayed onset and lower viral loads compared to the pre-emptive strategy. However, in female patients, the prophylactic strategy was associated with a strong impairment of glomerular filtration rate one year post-transplant (difference: -11.8 ± 4.3 ml min-1·1.73 m-2, p = 0.006). Additionally, we observed a tendency of higher incidence of acute rejection and severe BK virus reactivation in the prophylactic strategy group. While the prophylactic strategy was more effective for preventing CMV syndrome, our results suggest for the first time that the prophylactic strategy might lead to inferior transplantation outcomes in female patients, providing evidence for a strong association with sex. Further randomized controlled studies are necessary to confirm this potential negative effect.

Long-Term Outcomes and Prognostic Factors in Kidney Transplant Recipients with Polycystic Kidney Disease

Background

Polycystic kidney disease (PKD) accounts for approximately 15% of kidney transplants, but long-term outcomes in patients with PKD who have received a kidney transplant are not well understood.

Methods

In primary recipients of kidney transplants at our center (1994-2014), we compared outcomes of underlying PKD (N=619) with other native diseases (non-PKD, N=4312). Potential factors influencing outcomes in PKD were evaluated using Cox proportional-hazards regression and a rigorous multivariable model.

Results

Patients with PKD were older and were less likely to be sensitized or to experience delayed graft function (DGF). Over a median follow-up of 5.6 years, 1256 of all recipients experienced death-censored graft failure (DCGF; 115 patients with PKD) and 1617 died (154 patients with PKD). After adjustment for demographic, dialysis, comorbid disease, surgical, and immunologic variables, patients with PKD had a lower risk of DCGF (adjusted hazard ratio [aHR], 0.73; 95% CI, 0.57 to 0.93; P=0.01) and death (aHR, 0.62; 95% CI, 0.51 to 0.75; P<0.001). In our multiadjusted model, calcineurin-inhibitor (CNI) use was associated with lower risk of DCGF (aHR, 0.45; 95% CI, 0.26 to 0.76; P=0.003), whereas HLA mismatch of five to six antigens (aHR, 2.1; 95% CI, 1.2 to 3.64; P=0.009) was associated with higher likelihood of DCGF. Notably, both pretransplant coronary artery disease (CAD) and higher BMI were associated with increased risk of death (CAD, aHR, 2.5; 95% CI, 1.69 to 3.71; P<0.001; per 1 kg/m² higher BMI, aHR, 1.07; 95% CI, 1.04 to 1.11; P<0.001), DCGF, and acute rejection. Nephrectomy at time of transplant and polycystic liver disease were not associated with DCGF/death. Incidence of post-transplant diabetes mellitus was similar between PKD and non-PKD cohorts.

Conclusions

Recipients with PKD have better long-term graft and patient survival than those with non-PKD. Standard practices of CNI use and promoting HLA match are beneficial in PKD and should continue to be promoted. Further prospective studies investigating the potential benefits of CNI use and medical/surgical interventions to address CAD and the immunologic challenges of obesity are needed.

Podcast

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Sex disparities in dialysis initiation, access to waitlist, transplantation and transplant outcome in German patients with renal disease-A population based analysis

Background

Renal transplantation access and outcome differ between men and women, but no analysis has considered all transition phases and transplant outcome using the same data set. We analyzed sex disparities in all phases of patients’ clinical path (progression to dialysis, waitlisting, transplantation, graft failure/death).

Methods

In a population based approach using health insurance data (2005–2013) we examined patients’ risk of changing from one phase to another applying Cox Proportional Hazards model.

Results

After adjusting for age and comorbidities, women had a 16% lower risk of progression to ESRD (HR/95%-CI: 0.84/0.79–0.88). Access to the waitlist was lowered by 18% in women compared to men (HR/95%-CI: 0.82/0.70–0.96). An age stratified analysis did not reveal differences in any age group. Once waitlisted, the chance to receive a transplant was identical (HR/95%-CI: 0.96/0.81–1.15). The risk of transplant failure/death was identical for both sexes (HR/95%-CI: 0.99/0.73–1.35), but the effect was modified by age: in younger women (18–45 years) the risk was twice as high compared to men (HR/95%-CI: 2.08/1.04–4.14), whereas the risk in elderly women (> 65 years) was only half the risk of men (HR/95%-CI: 0.47/0.24–0.93).

Conclusion

Sex disparities occurred at different steps in the history of patients with renal disease and affected progression to dialysis, waitlisting and transplantation outcome in a population with equal access to medical treatment.

African American polycystic kidney patients receive higher risk kidneys, but do not face increased risk for graft failure or post-transplant mortality

African Americans (AA) are disproportionately affected by end-stage renal disease (ESRD) and have worse outcomes following renal transplantation. Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic condition leading to ESRD necessitating transplant. We explored this population with respect to race by conducting a retrospective analysis of the UNOS database between 2005 and 2019. Our study included 10,842 (AA n = 1661; non-AA n = 9181) transplant recipients whose primary diagnosis was ADPKD. We further stratified the AA ADPKD population with respect to blood groups (AA blood type B n = 295 vs AA non-B blood type n = 1366), and also compared this cohort to AAs with a diagnosis of DM (n = 16,706) to identify unique trends in the ADPKD population. We analyzed recipient and donor characteristics, generated survival curves, and conducted multivariate analyses. African American ADPKD patients waited longer for transplants (924 days vs 747 days P < .001), and were more likely to be on dialysis (76% vs 62%; p < .001). This same group was also more likely to have AA donors (21% vs 9%; p < .001) and marginally higher KDPI kidneys (0.48 vs 0.45; p < .001). AA race was a risk factor for delayed graft function (DGF), increasing the chance of DGF by 45% (OR 1.45 95% CI 1.26-1.67; p < .001). AA race was not associated with graft failure (HR 1.10 95% CI 0.95-1.28; p = .21) or patient mortality (HR 0.84 95% CI 0.69-1.03; p = .09). Racial disparities exist in the ADPKD population. They should be continually studied and addressed to improve transplant equity.

Sex differences in renal ischemia-reperfusion injury

Ischemia-reperfusion injury of the kidney is caused by the sudden and temporary obstruction of blood flow to the organ. Renal ischemia-reperfusion injury is associated with high morbidity and mortality, but effective therapies are lacking. Sexual dimorphism in renal injury has been acknowledged since the 1940s, and the possible role of sex hormones has been intensively investigated in the past decades. Clinical and experimental data demonstrate sexual differences in renal anatomy, physiology, and susceptibility to renal diseases including but not limited to ischemia-reperfusion injury. Some data suggest the protective role of female sex hormones, whereas others highlight the detrimental effect of male hormones in renal ischemia-reperfusion injury. Although the important role of sex hormones is evident, the exact underlying mechanisms remain to be elucidated. This review focuses on collecting the current knowledge about sexual dimorphism of renal ischemia-reperfusion injury, with emphasis on molecular mechanisms and potential novel therapeutic strategies.

Impact of Combinations of Donor and Recipient Ages and Other Factors on Kidney Graft Outcomes

As the availability of kidneys for transplantation continues to be outpaced by its growing demand, there has been an increasing utilization of older deceased donors in the last decades. Considering that definition of factors that influence deceased donor kidney transplant outcomes is important for allocation policies, as well as for individualization of post-transplant care, the purpose of this study was determine the risks for death censored graft survival and for patient survival conferred by older age of the donor in the context of the age of the recipient and of risk factors for graft and/or patient survival. The investigation was conducted in a single-center cohort of 5,359 consecutive first kidney transplants with adult deceased donors performed on non-prioritized adult recipients from January 1, 2002, to December 31, 2017. Death censored graft survival and patient survival were lower in older donors, whereas graft survival was higher and patient survival was lower in old recipients. The analyses of combinations of donor and recipient ages showed that death censored graft survival was lower in younger recipients in transplants from 18 to 59-year old donors, with standard or extended criteria, but no difference in graft survival was observed between younger and older recipients when the donor was ≥ 60-year old. Patient survival was higher in younger recipients in transplants with younger or older donors. Two to six HLA-A,B,DR mismatches, when compared to 0-1 MM, conferred risk for death-censored graft survival only in transplants from younger donors to younger recipients. Pre-transplant diabetes conferred risk for patient survival only in 50–59-year old recipients, irrespectively, of the age of the donor. Time on dialysis ≥ 10 years was a risk factor for patient survival in transplants with all donor-recipient age combinations, except in recipients with ≥ 60 years that received a kidney from an 18–49-year old donor. In conclusion, the results obtained in this study underline the importance of analyzing the impact of the age of the donor taking into consideration different scenarios.

Equally Interchangeable? How Sex and Gender Affect Transplantation

Organ transplantation as an option to overcome end-stage diseases is common in countries with advanced healthcare systems and is increasingly provided in emerging and developing countries. A review of the literature points to sex- and gender-based inequity in the field with differences reported at each step of the transplant process, including access to a transplantation waiting list, access to transplantation once waitlisted, as well as outcome after transplantation. In this review, we summarize the data regarding sex- and gender-based disparity in adult and pediatric kidney, liver, lung, heart, and hematopoietic stem cell transplantation and argue that there are not only biological but also psychological and socioeconomic issues that contribute to disparity in the outcome, as well as an inequitable access to transplantation for women and girls. Because the demand for organs has always exceeded the supply, the transplant community has long recognized the need to ensure equity and efficiency of the organ allocation system. In the spirit of equity and equality, the authors call for recognition of these inequities and the development of policies that have the potential to ensure that girls and women have equitable access to transplantation.

Neighborhood Poverty and Sex Differences in Live Donor Kidney Transplant Outcomes in the United States

BACKGROUND

Neighborhood poverty has been associated with worse outcomes after live donor kidney transplantation (LDKT), and prior work suggests that women with kidney disease may be more susceptible to the negative influence of poverty than men. As such, our goal was to examine whether poverty differentially affects women in influencing LDKT outcomes.

METHODS

Using data from the Scientific Registry of Transplant Recipients and US Census, we performed multivariable Cox regression to compare outcomes among 18 955 women and 30 887 men who received a first LDKT in 2005-2014 with follow-up through December 31, 2016.

RESULTS

Women living in poor (adjusted hazard ratio [aHR], 1.30; 95% confidence interval [CI], 1.13-1.50) and middle-income (aHR, 1.26; 95% CI, 1.14-1.40) neighborhoods had higher risk of graft loss than men, but there were no differences in wealthy areas (aHR, 1.07; 95% CI, 0.88-1.29). Women living in wealthy (aHR, 0.71; 95% CI, 0.59-0.87) and middle-income (aHR, 0.82; 95% CI, 0.74-0.92) neighborhoods incurred a survival advantage over men, but there were no statistically significant differences in mortality in poor areas (aHR, 0.85; 95% CI, 0.72-1.01).

CONCLUSIONS

Given our findings that poverty is more strongly associated with graft loss in women, targeted efforts are needed to specifically address mechanisms driving these disparities in LDKT outcomes.

The Impact of Sex on Alloimmunity

Transplantation outcomes are known to be affected by multiple factors, including donor and recipient sex. Aside from the physiological characteristics of male and female donor allografts, accumulating evidence suggests that additional features underlie sex-specific immune responses that affect graft survival. We discuss here aspects of innate and adaptive alloimmunity that are specific to males and females in the context of underlying genetic and hormonal factors. These differences likely contribute to the observed disparities in graft survival. Understanding these features in more detail may lead to improved strategies for optimizing the results of organ transplantation.

Impact of Sex Disparities on Outcomes of Living-Donor Kidney Transplant in Egypt: Data of 979 Patients

OBJECTIVES

Renal transplant is the criterion standard for treatment of end-stage renal disease. The effects of disparities between men and women on renal transplant outcomes have been evaluated in many studies but with debatable results. It has been suggested that female kidney donors have poor outcomes after transplant compared with male kidney donors, especially when implanted in a male recipient. The aim of the study was to evaluate the effects of sex on living-donor kidney transplant outcome.

MATERIALS AND METHODS

The data of 979 patients who underwent living-donor kidney transplant from January 2000 to December 2010 at a single center were reviewed retrospectively. The patients were divided into 4 groups according to recipient and donor sex: male donor-to-male recipient (n = 307), male donor-to-female recipient (n = 132), female donor-to-male recipient (n = 411), and female donor-to-female recipient (n = 129). We compared the demographic characteristics, posttransplant rejection and complications, and graft and patient survival rates among the groups.

RESULTS

Male recipients were older than female recipients, whereas male donors were younger than female donors (P < .001). No statistically significant differences were shown regarding recipient body mass index, ischemia time and time to diuresis, and acute and chronic rejection rates between the groups. Graft (P = .947) and patient (P = .421) survival rates were comparable between groups.

CONCLUSIONS

Donor and recipient sex had no significant effect on outcomes of living-donor renal allograft recipients.

Association of Sex with Risk of Kidney Graft Failure Differs by Age

Prior studies of sex differences in kidney graft survival showed conflicting results. We hypothesized that the association between recipient sex and kidney graft failure risk differs by recipient age and donor sex. We evaluated 159,417 patients recorded in the Scientific Registry of Transplant Recipients database who received a first deceased-donor kidney transplant (1995-2013). We used time-varying Cox models to estimate the association between recipient sex and death-censored graft failure. Models, stratified on donor sex and adjusted for potential confounders, included a recipient sex by current age interaction term. Among recipients of male donors, females of all ages had significantly higher graft failure risks than males (adjusted hazard ratios 0-14 years: 1.51 [95% confidence intervals 1.19 to 1.90]; 15-24 years: 1.37 [1.18 to 1.59]; 25-44 years: 1.14 [1.03 to 1.26]; 45 years: 1.05 [1.01 to 1.09]). Among recipients of female-donor grafts, only female recipients aged 15-24 years had a significantly higher graft failure risk than their male counterparts had (1.28 [1.06 to 1.53]). Indeed, female recipients aged ≥45 years had a significantly lower graft failure risk than their male counterparts had (0.95 [0.91 to 0.99]). These observations might be explained by the combined influence of several factors, including recognition of sex-determined minor histocompatibility antigens, influence of sex hormones on immune activation, sex- and age-related differences in medication adherence, and sex-related differences in body size. Additional studies should determine whether sex- and age-specific immunosuppression strategies are warranted for kidney graft recipients.

Sex differences in transplantation

Sex plays a role in the incidence and progression of a wide variety of diseases and conditions related to transplantation. Additionally, a growing body of clinical and experimental evidence suggests that sex can impact the pharmacokinetics and pharmacodynamics of several commonly used immunosuppressive and anti-infective drugs in transplant recipients. A better understanding of these sex differences will facilitate advances in individualizing treatment for patients and improve outcomes of solid organ transplantation. Here, we provide a review of sex-related differences in transplantation and highlight opportunities for future research directions.

Graft survival rate of renal transplantation during a period of 10 years in Iran

BACKGROUND

Kidney transplantation is a preferred treatment for many patients with end-stage renal disease (ESRD) and is far more profitable than hemodialysis. Analyzing renal transplantation data can help to evaluate the effectiveness of transplantation interventions. The aim of this study was to determine the organ survival rate after kidney transplantation during a period of 10 years (March 2001-March 2011) among transplanted patients in Arak, Markazi Province, Iran.

MATERIALS AND METHODS

In this historical cohort study, all recipients of kidney transplantation from Arak, Markazi Province, Iran who had medical records in Valiasr Hospital and "charity for kidney patients" of Arak, Markazi Province, Iran during a period of 10 years from March 2001 to March 2011 were included. Data collected by using checklists were completed from patients' hospital records. Kaplan-Meier method was used to determine the graft cumulative survival rate, log-rank test to compare survival curves in subgroups, and Cox regression model to define the hazard ratio and for ruling out the intervening factors. Statistical analysis was conducted by Statistical Package for the Social Sciences (SPSS) 20 and Stata 11.

RESULTS

Mean duration of follow-up was 55.43 ± 42.02 months. By using the Kaplan-Meier method, the cumulative probability of graft survival at 1, 3, 5, 7, and 10 years was 99.1, 97.7, 94.3, 85.7, and 62.1%, respectively. The number of dialysis by controlling the effect of other variables had a significant association with the risk of graft failure [hazard ratios and 95% confidence interval (CI): 1.47 (1.02-2.13)].

CONCLUSION

This study showed that the graft survival rate was satisfactory in this community and was similar to the results of single-center studies in the world. Dialysis time after transplantation was a significant predictor of survival in the recipients of kidney transplantation that should be considered.

Gender in the allocation of organs in kidney transplants: meta-analysis

OBJECTIVE

To analyze whether gender influence survival results of kidney transplant grafts and patients.

METHODS

Systematic review with meta-analysis of cohort studies available on Medline (PubMed), LILACS, CENTRAL, and Embase databases, including manual searching and in the grey literature. The selection of studies and the collection of data were conducted twice by independent reviewers, and disagreements were settled by a third reviewer. Graft and patient survival rates were evaluated as effectiveness measurements. Meta-analysis was conducted with the Review Manager^® 5.2 software, through the application of a random effects model. Recipient, donor, and donor-recipient gender comparisons were evaluated.

RESULTS

: Twenty-nine studies involving 765,753 patients were included. Regarding graft survival, those from male donors were observed to have longer survival rates as compared to the ones from female donors, only regarding a 10-year follow-up period. Comparison between recipient genders was not found to have significant differences on any evaluated follow-up periods. In the evaluation between donor-recipient genders, male donor-male recipient transplants were favored in a statistically significant way. No statistically significant differences were observed in regards to patient survival for gender comparisons in all follow-up periods evaluated.

CONCLUSIONS

The quantitative analysis of the studies suggests that donor or recipient genders, when evaluated isolatedly, do not influence patient or graft survival rates. However, the combination between donor-recipient genders may be a determining factor for graft survival.

Gender differences in renal transplant graft survival

BACKGROUND/PURPOSE

A long-term retrospective study was conducted to assess the risk factors of renal transplant graft failure focusing on the effects of gender of both the donor and the recipient.

METHODS

Medical records of primary renal transplantation performed in a single transplant hospital were reviewed. Cases of ABO incompatibility, positive cross-matches, or multiple organ transplants were excluded. A total of 766 patient records were reviewed, and variables were analyzed with Kaplan-Meier survival curves and Cox regression to determine the independent factors associated with graft survival.

RESULTS

The overall 5-year graft and patient survival rates were 84.7% and 92.2%, respectively. Univariate analysis showed significantly poorer prognosis in male patients and in those with acute rejection, delayed function, or more mismatches in human lymphocyte antigens. Multivariate analysis with step-wise regression identified three independent prognostic factors for poor graft survival (male gender, acute rejection, and delayed function). The 5-year graft survival rates for female and male patients were 87.9% and 81.3%, respectively. The risk ratio of graft failure for male renal transplant recipients was 1.3732, when compared with that for female patients. The risk ratios for those with acute rejection and delayed function were 1.8330 and 1.5422, respectively.

CONCLUSION

Male gender, in addition to acute rejection and delayed function, was found to be an independent prognostic factor for poor renal transplant survival in this long-term retrospective study.

The effect of donor-recipient gender mismatch on short- and long-term graft survival in kidney transplantation: a systematic review and meta-analysis

BACKGROUND

There is no limitation of gender matching in renal transplantation. This study was intended to evaluate its effect on short- and long-term graft survival.

METHODS

PubMed, the Web of Knowledge, Medline, the Cochrane Library, and two additional Chinese databases were searched. The data were then abstracted and meta-analyzed.

RESULTS

14 studies involving 445 279 patients were included. Each study reported data on the four gender matches (male donor-male recipient, MDMR; male donor-female recipient, MDFR; female donor-male recipient, FDMR; female donor-female recipient, FDFR). The pooled risk ratios (RRs) for 0.5-, 1-, 2-, 3-, 5-, and 10-yr graft survival rates showed that the FDMR group had the worst outcomes, and when recipients were female, short-term graft survival was worse, but long-term graft survival was better. The differences between groups changed with time.

CONCLUSIONS

FDMR patients showed poor graft survival. The female recipients had worse short-term graft survival but the best long-term graft survival. This study introduces an important consideration into donor-recipient matching in renal transplantation.

Twenty-year survivors of kidney transplantation

There have been few studies of patients with renal allografts functioning for more than 20 years. We sought to identify clinical factors associated with ultra long-term (>20 year) renal allograft survival and to describe the clinical features of these patients. We performed a retrospective analysis of the Irish Renal Transplant Database and included 1174 transplants in 1002 patients. There were 255 (21.74%) patients with graft function for 20 years or more. Multivariate analysis identified recipient age (HR 1.01, CI 1.01-1.02), gender (male HR 1.25, CI 1.08-1.45), acute rejection (HR 1.26, CI 1.09-1.45) and transplant type (living related donor vs. deceased donor) (HR 0.52, CI 0.40-0.66) as significantly associated with long-term graft loss. Median serum creatinine was 115 μmol/L. The 5-year graft survival in 20-year survivors was 74.7%. The mean age at death was 62.7 years (±10.6). The most common causes of death were cardiovascular disease and malignancy. The two major causes of graft loss were death (with function) and interstitial fibrosis/tubular atrophy. Comorbidities included skin cancer (36.1%), coronary heart disease (17.3%) and other malignancies (14.5%). This study identifies factors associated with long-term allograft survival and a high rate of morbidity and early mortality in long-term transplant recipients.

Influence of donor and recipient gender as well as selected factors on the five-year survival of kidney graft

The aim of the study was to determine the impact of the gender of renal allograft donor and recipient on the graft function over a 5-year follow-up period.

MATERIAL AND METHODS

The 154 kidney grafts from 77 donors transplanted into recipients of both genders. Two study groups were formed: one group consisted of male donors, while the other consisted of female donors. The recipients in each of the groups consisted of a pair, one male and one female.

RESULTS

71% of grafts survived the five-year period in the group of male and female recipients when the donor was male; in case of female donors, the rate was 62.5%. Depending on the gender of the donor and the recipient, the rates of grafts with five-year survival were as follows: 79.2% for male donors and female recipients (MF); 62.5% for male donors and male recipients (MM). The difference between both groups was not statistically significant. In the case of female donors and male recipients (FM), the five-year survival rate was 58.3%, while in female donors and female recipients, the five-year survival rate was 64.1%.

CONCLUSIONS

Grafts from male donors show a trend towards better five-year survival compared to grafts from female donors. The highest five-year survival rate was observed when the donor was male and the recipient was female; the lowest rate was observed for female donors and male recipients.

Donor-recipient gender and size mismatch affects graft success after kidney transplantation

BACKGROUND

Female recipients of male kidneys have an inferior graft survival, and patients receiving larger kidneys relative to their body size may have a graft survival advantage. Thus, graft survival may be affected by both gender and kidney size mismatches. The objective of this study was to analyze the possible confounding effect of body mass mismatch (body mass as proxy for kidney size) between female recipients of male donor kidneys.

STUDY DESIGN

A total of 668 kidney transplantations between 1996 and 2005 at our center were studied retrospectively. Graft and patient survival were determined by Kaplan-Meier estimation. Multivariate Cox proportional analyses were performed to determine the hazards of graft loss.

RESULTS

There were 146 female recipients of male kidneys. Compared with all other gender combinations, this group had the lowest unadjusted graft survival (86%, 79%, and 78% vs 92%, 88%, and 86% at 1, 2, and 3 years, respectively; log-rank p = 0.01). Donor body mass index (BMI) correlated with donor kidney size (p < 0.001). Male kidneys were a risk factor of graft loss for female recipients (hazard ratio [HR] 3.45, 95% CI 1.40 to 8.51, p = 0.01), but male donors with a larger BMI relative to female recipients' significantly reduced the risk (HR 0.19, 95% CI 0.05 to 0.67, p = 0.01).

CONCLUSIONS

The inferior graft survival for female recipients of male donor kidneys is mitigated by male donors with a larger BMI.

Outcome of kidney transplantation in Canadian Aboriginal children in the province of British Columbia

Renal transplantation remains the therapy of choice for children and adolescents with ESRD. Differences in graft survival are observed in kidney transplant recipients of different race and ethnicities. Data in pediatric populations are limited and confounded by disparities in access to health care. We performed a retrospective single Canadian centre database review to determine the short- and long-term outcomes of kidney transplantation in Aboriginal children compared to non-Aboriginals. A total of 159 primary renal transplant recipients at BCCH between 1985 and 2005 were examined (15% Aboriginal). Aboriginal children had different etiologies of ESRD, and a higher percentage of females, but were similar in age at transplantation, cold ischemia time and living donation rate. Early graft outcomes such as delayed graft function, episodes of acute rejection in the first year post-transplant and estimated glomerular function rate at one yr were similar in both groups. Long-term graft survival, however, was significantly worse in the Aboriginal group, with a significantly increased rate of late rejections: 50% compared with 26.7% among non-Aboriginals (p = 0.03). In a province with uniform access to health care, significant differences in long-term graft outcome exist among Aboriginal children compared with non-Aboriginals.

Longitudinal analysis of physical activity, fluid intake, and graft function among kidney transplant recipients

Self-care is recommended to kidney transplant recipients as a vital component to maintain long-term graft function. However, little is known about the effects of physical activity, fluid intake, and smoking history on graft function. This longitudinal study examined the relationship between self-care practices on graft function among 88 new kidney transplant recipients in Chicago, IL and Albany, NY between 2005 and 2008. Participants were interviewed, completed surveys, and medical charts were abstracted. Physical activity, fluid intake, and smoking history at baseline were compared with changes in estimated glomerular filtration rate (eGFR) (every 6 months up to 1 year) using bivariate and multivariate regression analysis, while controlling for sociodemographic and clinical transplant variables. Multivariate analyses revealed that greater physical activity was significantly (P < 0.05) associated with improvement in GFR at 6 months; while greater physical activity, absence of smoking history, and nonwhite ethnicity were significant (P < 0.05) predictors of improvement in GFR at 12 months. These results suggest that increasing physical activity levels in kidney recipients may be an effective behavioral measure to help ensure graft functioning. Our findings suggest the need for a randomized controlled trial of exercise, fluid intake, and smoking history on GFR beyond 12 months.

Comparison of the predictive performance of eGFR formulae for mortality and graft failure in renal transplant recipients

BACKGROUND

To date, efforts have focused on assessing estimated glomerular filtration rate (eGFR) formulae against measured GFR. However, a more appropriate clinical gold standard is one conveying a defined clinical disadvantage. In renal transplantation, these measures are mortality and graft failure.

METHODS

The Long Term Efficacy and Safety Surveillance database was used to analyze 1344 renal transplant recipients. eGFR was assessed 6 months posttransplantation with the following formulae: Cockcroft-Gault; Walser; Nankivell; abbreviated modification of diet in renal disease (aMDRD); MDRD7; Rule's refitted MDRD; and Mayo Clinic. The outcome measures were mortality and graft failure.

RESULTS

Although eGFR was statistically associated with subsequent mortality and graft failure in the Cox model (irrespective of which eGFR formula was used), the clinical utility of eGFR was moderate at best in predicting subsequent mortality and graft failure. No clinically relevant or statistically significant difference was discernable between formulae, with a maximum area under the receiver operating characteristic curve of 0.63 and 0.61 for 3- and 5-year mortality, respectively, and 0.66 and 0.60 for 3- and 5-year graft failure, respectively. Serum creatinine used in isolation displayed similar predictive utility, and no improvement was seen by investigating the change in creatinine or eGFR between 6 and 12 months.

CONCLUSIONS

In summary, seven eGFR equations showed similar and limited utility in predicting mortality and graft failure after renal transplantation. This has important implications for the management of renal transplant recipients and the use of an eGFR as a surrogate endpoint in clinical trials.

Age and comorbidities are effect modifiers of gender disparities in renal transplantation

Women have less access to kidney transplantation than men, but the contributions of age and comorbidity to this disparity are largely unknown. We conducted a national cohort study of 563,197 patients with first-onset ESRD between 2000 and 2005. We used multivariate generalized linear models to evaluate both access to transplantation (ATT), defined as either registration for the deceased-donor waiting list or receiving a live-donor transplant, and survival benefit from transplantation, defined as the relative rate of survival after transplantation compared with the rate of survival on dialysis. We compared relative risks (RRs) between women and men, stratified by age categories and the presence of common comorbidities. Overall, women had 11% less ATT than men. When the model was stratified by age, 18- to 45-yr-old women had equivalent ATT to men (RR 1.01), but with increasing age, ATT for women declined dramatically, reaching a RR of 0.41 for those who were older than 75 yr, despite equivalent survival benefits from transplantation between men and women in all age subgroups. Furthermore, ATT for women with comorbidities was lower than that for men with the same comorbidities, again despite similar survival benefits from transplantation. This study suggests that there is no disparity in ATT for women in general but rather a marked disparity in ATT for older women and women with comorbidities. These disparities exist despite similar survival benefits from transplantation for men and women regardless of age or comorbidities.

Renal ischemia: does sex matter?

Renal ischemia is a common complication in the perioperative period that leads to a high rate of morbidity and mortality. As in other forms of ischemia (i.e., cardiac, neurologic), the incidence and outcome of renal ischemia is strikingly sex-specific. Sexual dimorphism in response to renal injury has been noted for many years, but is now the subject of both clinical and experimental research. Clinically, women experience a lower incidence of perioperative acute renal failure, with the exception of cardiac surgery. Experimental science is now producing tantalizing clues that sex steroids, both male and female, play a role in the kidney's response to ischemia. In this review, we evaluated sex differences in perioperative renal failure and in the pathophysiology of renal ischemia/reperfusion injury. Although much work remains to characterize the biological mechanisms involved, the data are sufficient to support consideration of gender and the use of medications that impact steroid availability in the perioperative plan of care.

[Simultaneous pancreas-kidney transplantation. Influence of donor and recipient gender]

BACKGROUND

Differences in graft survival due to gender have been reported after transplantation of the kidney, liver, and heart. However, little is known about the role of donor and recipient gender in simultaneous pancreas-kidney transplantation.

METHODS

Single-centre analysis was performed of first simultaneous pancreas-kidney transplantations performed between 1994 and 2005 at the Bochum Transplant Center in Germany (n=218).

RESULTS

Recipients of female donor organs exhibited acute organ rejections earlier and more frequently (P<0.05). Male recipients of organs from male donors had a lower risk of acute rejection than recipients of female donor organs (P<0.05). In addition to female donor gender, higher donor age and early kidney dysfunction were risk factors for perioperative rejection (P<0.05). Long-term kidney and pancreas function was best in male-donor-to-female-recipient transplants over the time periods of 7 and 3 years, respectively (P<0.05). Risk factors of long-term organ failure were: the need of revision laparotomy, organ rejection, and early postoperative organ dysfunction (P<0.05).

CONCLUSION

This is the first report of graft function after simultaneous pancreas-kidney transplantation looking specifically at gender differences with respect to donor and recipient. There was an increased risk of organ rejection of female donor organs.

Sex differences in response to cyclosporine immunosuppression in experimental kidney transplantation

1. Female donors and recipients have increased risk of acute rejection and subsequent chronic allograft nephropathy (CAN), especially when cyclosporine A (CsA) is used. Decreased renal nitric oxide (NO) production is associated with chronic kidney disease. In the present study, we investigated the impact of gender, CsA dose and renal NO synthase (NOS) on CAN. 2. Kidneys from male and female F344 rats were transplanted into same-sex Lewis allograft or F344 isograft recipients and recipient rats were treated with 1.5 or 3 mg/kg per day CsA for 10 days. Grafts were removed at 22 weeks post-transplantation. Normal two-kidney F344 rats were investigated as age-matched controls. 3. Low-dose CsA was associated with accelerated CAN in female rats compared with male rats; however, with high-dose CsA, allograft females had similar pathology/function to allograft males. Isograft females (similar to isograft males) had no graft failure and only slightly, albeit significantly, greater injury than age-matched controls. Isograft females had higher renal cortical neuronal (n) NOS but lower medullary endothelial (e) NOS than isograft males. There was no difference in renal eNOS and nNOS between allograft groups. 4. In conclusion, 1.5 mg/kg per day CsA is not sufficient to prevent early graft loss in females. When the dose of CsA is doubled, allograft females and males have similar post-transplant survival. Renal NOS expression was unremarkable in any transplant group.

Renal cortex neuronal nitric oxide synthase in response to rapamycin in kidney transplantation

Decreased renal neuronal nitric oxide synthase (nNOS) is present in various chronic kidney diseases although there is relative little known in chronic allograft nephropathy (CAN). Female sex increases the risk of acute rejection and calcineurin-inhibitor toxicity but decreases the risk of CAN. Rapamycin (RAPA) is an alternative immunosuppress although there is no information whether it is effective in females. We therefore investigated the efficacy of RAPA in both sexes and the impact of RAPA on renal cortex structure and nNOS expression. Male (M) and female (F) F344 kidneys were transplanted into same sex Lewis (ALLO) or F344 (ISO) recipients and treated with 1.6 mg/kg/day of RAPA for 10 days. Grafts were removed for renal histology and endothelial (e)NOS and neuronal (n)NOS protein measurements at 22 weeks. All ALLO rats survived without acute rejection. ALLO F survived with mild proteinuria and CAN at 22 weeks similar to ALLO M, while ISO F had better outcome than ISO M. Cortical nNOSalpha was undetectable in all RAPA groups; however, nNOSbeta transcript and protein were compensatory increased. Both ALLO and ISO F showed higher medullary nNOSalpha but lower cortical eNOS abundance than M groups. In male ALLO RAPA decreased renal cortical nNOSalpha but increased nNOSbeta expression. This may represent compensatory upregulation of nNOSbeta when nNOSalpha-derived NO is deficient.