Immunosenescence in renal transplantation: a changing balance of innate and adaptive immunity

Long-term outcomes of induction immunosuppression for kidney transplant recipients with HIV who have average immunologic risk: An inverse probability treatment weighting analysis

We analyzed the Scientific Registry of Transplant Recipients (2004-2022) for primary kidney transplant recipients with HIV who had average immunologic risk and were discharged on tacrolimus/mycophenolate mofetil (with or without corticosteroids). Recipients were grouped by induction type: rabbit antithymocyte globulin (r-ATG, n = 688) and human interleukin-2 receptor antagonist (IL2Ra, n = 467). Kaplan-Meier curves were generated to examine recipient and graft survival by induction type. We used mixed Cox proportional hazard models to determine associations between induction type and outcomes of interest, with adjustments for recipient and donor factors and transplant center as a random effect. Regression with propensity score weighting reduced selection bias from nonrandom induction allocation. The unadjusted 10-year survival rate was 57% for those receiving r-ATG and 64% for those receiving IL2Ra (P < .001). Adjusted risk of death was significantly lower for IL2Ra induction than r-ATG induction with Cox multivariable (hazard ratio, 0.65; 95% CI, 0.47-0.91; P = .01) and inverse probability treatment weighting (hazard ratio, 0.38; 95% CI, 0.29-0.50; P < .01) models. Death-censored kidney graft survival did not differ by induction type in either model. The 1-year rejection rate was 10.1% and 11.6% for r-ATG and IL2Ra recipients, respectively (P = .52). Overall, IL2Ra conferred better long-term survival than r-ATG without increased risk of graft loss.

Outcomes of Older Primary Kidney Transplant Recipients by Induction Agent and High-risk Viral Discordance Status in the United States

Background

The impact of induction type or high-risk viral discordance on older kidney transplant recipients is unclear. Herein, we analyzed the association between induction type, viral discordance, and outcomes for older recipients.

Methods

We analyzed the Scientific Registry of Transplant Recipients standard analysis file for all primary kidney transplant recipients older than 55 y who were transplanted between 2005 and 2022. All transplants were crossmatch negative and ABO-compatible. Recipients were discharged on tacrolimus and mycophenolate ± steroids. Recipients were categorized into 3 groups by induction received: rabbit antithymocyte globulin (r-ATG; N = 51 079), interleukin-2 receptor antagonist (IL-2RA; N = 22 752), and alemtuzumab (N = 13 465). Kaplan-Meier curves were generated for recipient and graft survival, and follow-up was censored at 10 y. Mixed-effect Cox proportional hazard models examined the association between induction type, high-risk viral discordance, and outcomes of interest. Models were adjusted for pertinent recipient and donor characteristics.

Results

Induction type did not predict recipient survival in the multivariable model, whereas Epstein-Barr virus high-risk discordance predicted 14% higher mortality (1.14 [1.07-1.21], P < 0.01). In the multivariable model for death-censored graft survival, alemtuzumab, but not IL-2RA, was associated with an increased risk of graft loss (1.18 [1.06-1.29], P < 0.01) compared with r-ATG. High-risk cytomegalovirus discordance predicted 10% lower death-censored graft survival (1.10 [1.01-1.19], P < 0.02). Live donor and preemptive transplantation were favorable predictors of survival.

Conclusions

In this large cohort of older transplant recipients, alemtuzumab, but not IL-2RA, induction was associated with an increased risk of graft loss compared with r-ATG. Cytomegalovirus and Epstein-Barr virus high-risk viral discordance portended poor graft and recipient survival, respectively.

Older age is associated with a distinct and marked reduction of functionality of both alloreactive CD4+ and CD8+ T cells

Introduction

Older recipient age is associated with a significant decreased risk for rejection after kidney transplantation which is incompletely understood.

Methods

In a longitudinal study, circulating alloreactive T cells were assessed of young (≤45 years) and older (≥55 years) stable kidney transplant recipients. Alloreactive T-cells were identified by CD137-expression and phenotype, cytokine producing and proliferative capacity, were evaluated using multiparameter flowcytometry.

Results

The results show that before transplantation frequencies of alloreactive CD4+ and CD8+ T-cells in older KT-recipients are significantly higher and shifted towards an effector memory-phenotype. However, the frequency of polyfunctional (≥2 pro-inflammatory cytokines) CD4+ T-cells was significantly lower and less IL2 was produced. The frequency of polyfunctional alloreactive CD4+ T-cells and proliferation of alloreactive T-cells donor-specifically declined after transplantation reaching a nadir at 12 months after transplantation, irrespective of age. A striking difference was observed for the proliferative response of alloreactive CD8+ T-cells. This was not only lower in older compared to younger recipients but could also not be restored by exogenous IL2 or IL15 in the majority of older recipients while the response to polyclonal stimulation was unaffected.

Conclusion

In conclusion, older age is associated with a distinct and marked reduction of functionality of both alloreactive CD4+ and CD8+ T-cells.

Beyond Human Limits: Harnessing Artificial Intelligence to Optimize Immunosuppression in Kidney Transplantation

The field of kidney transplantation is being revolutionized by the integration of artificial intelligence (AI) and machine learning (ML) techniques. AI equips machines with human-like cognitive abilities, while ML enables computers to learn from data. Challenges in transplantation, such as organ allocation and prediction of allograft function or rejection, can be addressed through AI-powered algorithms. These algorithms can optimize immunosuppression protocols and improve patient care. This comprehensive literature review provides an overview of all the recent studies on the utilization of AI and ML techniques in the optimization of immunosuppression in kidney transplantation. By developing personalized and data-driven immunosuppression protocols, clinicians can make informed decisions and enhance patient care. However, there are limitations, such as data quality, small sample sizes, validation, computational complexity, and interpretability of ML models. Future research should validate and refine AI models for different populations and treatment durations. AI and ML have the potential to revolutionize kidney transplantation by optimizing immunosuppression and improving outcomes. AI-powered algorithms enable personalized and data-driven immunosuppression protocols, enhancing patient care and decision-making. Limitations include data quality, small sample sizes, validation, computational complexity, and interpretability of ML models. Further research is needed to validate and enhance AI models for different populations and longer-term dosing decisions.

Investigating population-level immunosenescence: From bench to bedside

The immune response is remodeled with aging in a process called immunosenescence. Some immunologists conceive immunosenescence as an adaptation of immunity to the aged immune-environment rather than a merely collapsed reactivity of immune cells against microbes and tumor cells. Others believe on an uninterrupted activation of the innate immune system with aging, leading to a low grade, sterile and chronic proinflammatory state called inflammaging. For instance, it is possible that chronic infection by cytomegalovirus leads to persistent production of viral load. This phenomenon offers periodic stimuli to the immune system that ultimately contribute to the remodeling of the immune response. If investigating immunosenescence at the cellular level is already a difficult task, considering the population level is much more complex. However, by studying immunosenescence at the population level, we can extract valuable results with viable applications. While studies with animal models allow scientists to deepen their understanding of the mechanisms of immunosenescence, studying large populations can bring practical innovations to medicine and the health system. Many researchers and funders have dedicated themselves to producing methods for the evaluation of immunosenescence on a large scale, aiming to elucidate new mechanisms by which diseases are established in the elderly. The description of how the immune response is remodeled with aging emerges as a new tool to identify the subset of subjects in which unhealthy aging is a matter of time, to help better individualize clinical management and select patients who may benefit. of early interventions. This review focuses on functional assays as valuable methods for measuring the remodeling of the immune response with aging and discuss their clinical impact. We also recall fundamental concepts for understanding the aging process of the immune response. In addition, we highlight future prospects for immunosenescence research.

Lung transplantation in the septuagenarian can be successfully performed though long-term results impacted by diseases of aging

BACKGROUND

Advanced age is considered a risk factor for lung transplantation (LTX). We sought to evaluate the long-term outcomes of LTX in the septuagenarian.

METHODS

LTX recipients in the UNOS transplant registry (May 1, 2005 to June 12, 2020) were stratified into 18-59, 60-69, and > = 70 years of age. Recipient and transplant characteristics were evaluated for survival, cause of death (COD), length of stay (LOS), and complications. A Kaplan-Meier analysis examined long-term survival for all patients stratified by age, specifically looking at cause of death.

RESULTS

A total of 27632 recipients were identified. As recipients aged, we found a decrease in proportion of cystic fibrosis and an increase in restrictive disease while obstructive disease peaked in the 60-69yo cohort (p<0.001). Septuagenarians had higher rates of single LTX, male gender and white race (p<0.001). Older recipients had significantly longer donor recovery distances traveled with paradoxical shorter ischemic times, shorter hospital LOS and were transplanted at higher volume centers. There was no difference with in-hospital mortality among groups (p = 0.5). Acute rejection during initial hospitalization, rejection within 1 year, and post-transplant dialysis incidence decreased with age. Graft failure was a common COD in younger patients while malignancy and cardio/cerebrovascular diseases were common COD in > = 70yo.

CONCLUSION

Select septuagenarian LTX candidates may be safely transplanted with relatively few complications. Immunosenescence and conditions of the aged are likely contributing factors to the decreased rejection and graft failure observations. Septuagenarians should not be excluded from LTX consideration based solely on age. Transplantation in septuagenarians should only be done in very selected patients (screened for malignancies and atherosclerotic disease) and these recipients should be carefully followed after transplantation because of these risk factors. This article is protected by copyright. All rights reserved.

Pancreas Donor Risk Index and Preprocurement Pancreas Suitability Score for Prediction of Pancreas Transplant Outcomes

OBJECTIVES

The Pancreas Donor Risk Index and Preprocurement Pancreas Suitability Score were designed to assist in the evaluation of pancreases for transplant. Preprocurement Pancreas Suitability Score <17 and PancreasDonor Risk Index ≤1.57 were deemed ideal.We aimed to determine the ability ofthese scores to predict pancreas transplant outcomes.

MATERIALS AND METHODS

The Pancreas Donor Risk Index and the Preprocurement Pancreas Suitability Score were retrospectively calculated from a prospectively maintained database of consecutive pancreas transplants performed during a 13-year period (December 2004 to November 2017). Outcomes measuredwere rejection rate, graft and patient survival, and duration of hospital stay.

RESULTS

Of 159 pancreas transplants (108 simultaneous pancreas and kidney transplants, 33 pancreas after kidney transplants, 18 pancreas-only transplants), full data were available for 155 (97%) to calculate Pancreas Donor Risk Indexes and 129 (81%) to calculate Preprocurement Pancreas Suitability Scores. Fortyseven patients (30%) experienced at least 1 episode of acute rejection. We calculated Pancreas Donor Risk Indexes for 155 patients, and 19 (23%) and 27 (38%) were in the ≤1.57 and >1.57 groups, respectively (P = .047). We calculated Preprocurement Pancreas Suitability Scores for 129 patients, and 12 (21%) and 27 (32%) were in the <17 and ≥17 groups, respectively (P = .202). Donor age and recipientfemale sex were the main predictors forrejection (binary logistic regression, P < .05). One-year graft survival rates were 95% and 81% forthe ≤1.57 and >1.57 PancreasDonor Risk Index groups,respectively, and 95% and 80% forthe <17 and ≥17 Preprocurement Pancreas Suitability Score groups, respectively (not significant).

CONCLUSIONS

Pancreas Donor Risk Index and Preprocurement Pancreas Suitability Score were not helpful to predict graft/patient survival in our population. A higher Pancreas Donor Risk Index was associated with higher risk of graft rejection. Further studies with larger cohorts are required.

A Multi-Factorial Observational Study on Sequential Fecal Microbiota Transplant in Patients with Medically Refractory Clostridioides difficile Infection

Fecal microbiota transplantation (FMT) is highly effective in recurrent Clostridioides difficile infection (CDI); increasing evidence supports FMT in severe or fulminant Clostridioides difficile infection (SFCDI). However, the multifactorial mechanisms that underpin the efficacy of FMT are not fully understood. Systems biology approaches using high-throughput technologies may help with mechanistic dissection of host-microbial interactions. Here, we have undertaken a deep phenomics study on four adults receiving sequential FMT for SFCDI, in which we performed a longitudinal, integrative analysis of multiple host factors and intestinal microbiome changes. Stool samples were profiled for changes in gut microbiota and metabolites and blood samples for alterations in targeted epigenomic, metabonomic, glycomic, immune proteomic, immunophenotyping, immune functional assays, and T-cell receptor (TCR) repertoires, respectively. We characterised temporal trajectories in gut microbial and host immunometabolic data sets in three responders and one non-responder to sequential FMT. A total of 562 features were used for analysis, of which 78 features were identified, which differed between the responders and the non-responder. The observed dynamic phenotypic changes may potentially suggest immunosenescent signals in the non-responder and may help to underpin the mechanisms accompanying successful FMT, although our study is limited by a small sample size and significant heterogeneity in patient baseline characteristics. Our multi-omics integrative longitudinal analytical approach extends the knowledge regarding mechanisms of efficacy of FMT and highlights preliminary novel signatures, which should be validated in larger studies.

Immunosenescence as a reason of individualizing immunosuppressive therapy in kidney transplantation

Transplantation in elderly patients is obviously more challenging due to existing underlying diseases, changes in pharmacokinetics of immunosuppressive drugs, polypragmasy, and transformation of immunoreactivity (immunosenescence). Our review presents data on modification of adaptive and innate immunity during aging. It also considers the possibility of both reduced and adapted immunosuppressive therapy in elderly renal transplant recipients in achieving an optimal balance between efficacy and complications.

Clinical Outcomes of Older Kidney Transplant Recipients

BACKGROUND

Older kidney transplant recipients (OKTR) are vulnerable to infections and AKI, often prompting hospitalization. This study elucidates etiology of hospitalizations, AKI, and outcomes in OKTR.

METHODS

Retrospective study of 500 patients age ≥ 60, who underwent kidney transplantation from 2005-2015. Demographic, transplant, and outcomes data were collected.

RESULTS

OKTR had mean age 66 years; 59% males and 50% African Americans. 62% had at least one hospitalization post-transplant. Predictors of hospitalization were DGF, DM, panel reactive antibodies (PRA), dialysis duration. Hospitalization was mostly due to infection and surgical complications. Average length of stay was 6.4 days. OKTR with at least one hospitalization had 84% higher risk for graft loss (p=0.001). 56% of older kidney transplant recipients had at least one AKI episode post-transplant. Predictors of AKI included DGF, older, African American donor, and tacrolimus variability. The most common etiologies for AKI were infection, dehydration, and GI complications. OKTR with at least one AKI episode had 2.6-fold higher risk for graft loss (p<0.001).

CONCLUSIONS

Post-transplant hospitalization and AKI in OKTR significantly impact graft survival. Addressing comorbidities and risks in the pre-transplant and outpatient setting may help alleviate burden of hospitalization and risk of AKI in OKTR and improve graft outcomes.

Serum Albumin Level Before Kidney Transplant Predicts Post-transplant BK and Possibly Cytomegalovirus Infection

Introduction

Opportunistic viral infections cause extensive morbidity and mortality in kidney transplant recipients (KTRs). Low serum albumin levels before and after transplant have been associated with negative outcomes. However, it is uncertain whether serum albumin levels before transplantation are associated with the risk for post-transplantation opportunistic BK polyomavirus (BKV) or cytomegalovirus (CMV).

Methods

We reviewed all KTRs transplanted at our institution between 1 January 2005 and 31 December 2015 with serum albumin measured within 45 days before transplantation in a retrospective observational cohort study. Selected patients were stratified into 3 groups: normal albuminemia (≥3.5 g/dl), moderate hypoalbuminemia (3.49–2.5 g/dl), and severe hypoalbuminemia (<2.5 g/dl). Patients were observed for post-transplantation BKV or CMV according to standard of care.

Results

We included 1717 patients in this study; 72.3% had normal serum albumin, 26.3% had moderate hypoalbuminemia, and 1.5% had severe hypoalbuminemia. Moderate and severe hypoalbuminemia incurred a higher risk for BKV compared with normal serum albumin levels in univariable analysis (moderate hypoalbuminemia: hazard ratio [HR] = 1.5; 95% confidence interval [CI], 1.14–1.90; P = .003); severe hypoalbuminemia: HR = 2.15; 95% CI, 1.01–4.56; P = 0.05). Although not significant after multivariable adjustment, there was still 18% increased risk in moderate hypoalbuminemia and 64% in severe hypoalbuminemia for BKV compared with the normal albumin group. Moderate hypoalbuminemia was associated with a higher risk for CMV infection than normal serum albumin levels in multivariable analysis, although it was not statistically significant (HR = 1.15; 95% CI, 0.36–3.64; P = 0.81).

Conclusions

These findings suggest that pretransplantation hypoalbuminemia is associated with a higher risk for post-transplantation BKV and possibly CMV. More intense screening is warranted for these viruses in recipients with pretransplant hypoalbuminemia.

Remodeling of the Immune Response With Aging: Immunosenescence and Its Potential Impact on COVID-19 Immune Response

Elderly individuals are the most susceptible to an aggressive form of coronavirus disease (COVID-19), caused by SARS-CoV-2. The remodeling of immune response that is observed among the elderly could explain, at least in part, the age gradient in lethality of COVID-19. In this review, we will discuss the phenomenon of immunosenescence, which entails changes that occur in both innate and adaptive immunity with aging. Furthermore, we will discuss inflamm-aging, a low-grade inflammatory state triggered by continuous antigenic stimulation, which may ultimately increase all-cause mortality. In general, the elderly are less capable of responding to neo-antigens, because of lower naïve T cell frequency. Furthermore, they have an expansion of memory T cells with a shrinkage of the T cell diversity repertoire. When infected by SARS-CoV-2, young people present with a milder disease as they frequently clear the virus through an efficient adaptive immune response. Indeed, antibody-secreting cells and follicular helper T cells are thought to be effectively activated in young patients that present a favorable prognosis. In contrast, the elderly are more prone to an uncontrolled activation of innate immune response that leads to cytokine release syndrome and tissue damage. The failure to trigger an effective adaptive immune response in combination with a higher pro-inflammatory tonus may explain why the elderly do not appropriately control viral replication and the potential clinical consequences triggered by a cytokine storm, endothelial injury, and disseminated organ injury. Enhancing the efficacy of the adaptive immune response may be an important issue both for infection resolution as well as for the appropriate generation of immunity upon vaccination, while inhibiting inflamm-aging will likely emerge as a potential complementary therapeutic approach in the management of patients with severe COVID-19.

Changes of T-cell Immunity Over a Lifetime

T-cell immunity undergoes a complex and continuous remodeling with aging. Understanding those dynamics is essential in refining immunosuppression. Aging is linked to phenotypic and metabolic changes in T-cell immunity, many resulting into impaired function and compromised effectiveness. Those changes may impact clinical immunosuppression with evidences suggesting age-specific efficacies of some (CNI and mammalian target of rapamycin inhibitors) but not necessarily all immunosuppressants. Metabolic changes of T cells with aging have only recently been appreciated and may provide novel ways of immunosuppression. Here, we provide an update on changes of T-cell immunity in aging.

Assessment of infectious complications in elderly kidney transplant recipients receiving induction with anti-thymocyte globulin vs basiliximab

BACKGROUND

Elderly transplant recipients experience lower rates of acute rejection with higher rates of infectious complications compared to their younger counterparts. While less intensive immunosuppression may be preferable, there are no recommendations for depleting versus non-depleting induction strategies. We sought to compare infectious complications between anti-thymocyte globulin (ATG) and basiliximab (IL2RA) induction in elderly kidney transplant recipients (KTRs).

METHODS

We reviewed 146 KTRs ≥65 years receiving ATG or IL2RA induction. Per institution protocol, ATG was administered to patients with the following characteristics, irrespective of age: African American (AA), PRA ≥20%, and/or re-transplantation. Infectious complications (bacterial, viral, and invasive fungal) at 1 year were compared.

RESULTS

There were significantly more AA, deceased donors, and sensitized KTRs in the ATG group, reflecting criteria for induction agent. ATG KTRs experienced higher rates of overall infectious complications (77% vs 56%, P = .01), driven by increased bacterial (54% vs 39%, P = .08) and viral infections (51% vs 35%, P = .05). Urinary tract infections (UTIs) and CMV in particular occurred at high rates among ATG patients (46% and 32%, respectively). In multivariate analysis, the only independent risk factor associated with increased risk for infection was induction with ATG (adjusted HR 1.71 [95% CI 1.04-2.83], P = .04). Overall rates of immunologic outcomes were low.

CONCLUSION

Elderly KTRs receiving ATG are at an increased risk for infectious complications, largely attributed to high rates of UTIs and CMV. Additional strategies aimed at mitigating these complications in elderly patients requiring ATG may be beneficial.

Transplantation of Marginal Organs: Immunological Aspects and Therapeutic Perspectives in Kidney Transplantation

Recent data from the World Population Prospects projects that, by 2050, nearly all regions in the world will have a quarter or more of the population aged 60 and above. Chronic kidney disease (CKD) has a high global prevalence (~13%) worldwide, and the prevalence of chronic kidney disease and end-stage kidney disease increase with age. Kidney transplantation remains the best therapeutic option for end-stage kidney disease, offering a survival benefit in comparison with dialysis maintenance for most patients. This review focuses on immunological aspects of kidney transplantation in older patients and marginal donors, i.e., 60 years or older deceased kidney donors or 50–59 years old deceased kidney donors with comorbidities. Clinical outcomes of kidney recipients in terms of renal and patient survival are more than acceptable even for patients over 70. In this population, the first cause of graft loss is death with a functional graft. However, the inherent issues of these transplantations are the acceptance or refusal of frail kidney from an old donor and the increased immunogenicity of these organs in balance with potential frail and immunosenescent recipients. Finally, the immunosuppressive regimen itself is a challenge for the future of the transplant, to prevent adverse effects such as nephrotoxicity and higher risk of infections or cancer in a population already at risk. Belatacept may have a good place in the immunosuppressive strategy to improve efficacy and the safety posttransplantation.

Skewed T cell responses to Epstein-Barr virus in long-term asymptomatic kidney transplant recipients

Kidney transplant recipients (KTRs) abnormally replicate the Epstein Barr Virus (EBV). To better understand how long-term immunosuppression impacts the immune control of this EBV re-emergence, we systematically compared 10 clinically stable KTRs to 30 healthy controls (HCs). The EBV-specific T cell responses were determined in both groups by multiparameter flow cytometry with intra cellular cytokine staining (KTRs n = 10; HCs n = 15) and ELISpot-IFNγ assays (KTRs n = 7; HCs n = 7). The T/B/NK cell counts (KTRs n = 10; HCs n = 30) and the NK/T cell differentiation and activation phenotypes (KTRs n = 10; HCs n = 15/30) were also measured. We show that in KTRs, the Th1 effector CD4+ T cell responses against latent EBV proteins are weak (2/7 responders). Conversely, the frequencies total EBV-specific CD8+T cells are conserved in KTRs (n = 10) and span a wider range of EBNA-3A peptides (5/7responders) than in HCs (5/7responders). Those modifications of the EBV-specific T cell response were associated with a profound CD4+ T cell lymphopenia in KTRs compared to HCs, involving the naïve CD4+ T cell subset, and a persistent activation of highly-differentiated senescent CD8+ T cells. The proportion of total NK / CD8+ T cells expressing PD-1 was also increased in KTRs. Noteworthy, PD-1 expression on CD8+ T cells normalized with time after transplantation. In conclusion, we show modifications of the EBV-specific cellular immunity in long term transplant recipients. This may be the result of both persistent EBV antigenic stimulation and profound immunosuppression induced by anti-rejection treatments. These findings provide new insights into the immunopathology of EBV infection after renal transplantation.

Characterizing the pharmacokinetics and pharmacodynamics of immunosuppressant medicines and patient outcomes in elderly renal transplant patients

This review examines what is currently known about the pharmacokinetics and pharmacodynamics of commonly prescribed immunosuppressant medicines, tacrolimus, cyclosporine, mycophenolate and prednisolone, in elderly renal transplant recipients, and reported patient outcomes in this cohort. Renal transplantation is increasing rapidly in the elderly, however, currently, long-term patient outcomes are relatively poor compared to younger adults. Some studies have suggested that elderly recipients may have higher dose-adjusted exposure and/or lower clearance of the calcineurin inhibitors tacrolimus and cyclosporine; with one study reporting up to 50% reduction in tacrolimus exposure in the elderly. Elderly transplant recipients do not appear to have higher dosage-adjusted exposure to mycophenolic acid (MPA). The effects of ageing on the pharmacokinetics of prednisolone are unknown. Only one study has examined how aging effects drug target enzymes, reporting no difference in baseline inosine 5'-monophosphate dehydrogenase (IMPDH) activity and MPA-induced IMPDH activity in elderly compared to younger adult renal transplant recipients. In elderly transplant recipients, immunosenescence likely lowers the risk of acute rejection, but increases the risk of drug-related adverse effects. Currently, the three main causes of death in elderly renal transplant recipients are cardiovascular disease, infection and malignancy. One study has showed that renal transplant recipients aged over 65 years are seven times more likely to die with a functioning graft compared with young adults (aged 18-29 years). This suggests that an optimal balance between immunosuppressant medicine efficacy and toxicity is not achieved in elderly recipients, and further studies are needed to foster long-term graft and patient survival. Lower maintenance immunosuppressant targets in elderly recipients may decrease patient susceptibility to drug side effects, however, further studies are required and appropriate targets need to be established.

Differences in Gene Expression in Older Compared With Younger Kidney Transplant Recipients

BACKGROUND

For the growing numbers of older transplant patients, increased incidence of infection and death compared with younger patients may limit the many benefits provided by transplantation. However, little is known about age-associated immune dysfunction in the older transplant recipient.

METHODS

A cohort of 60 kidney transplant recipients, 23 older (≥ 60y) and 37 younger (30-59y), matched on antithymocyte induction and donor type (living vs deceased) was evaluated. Gene expression in peripheral blood mononuclear cells 3 months after kidney transplantation was analyzed to compare differences between older and younger patients.

RESULTS

Proinflammatory genes were upregulated in older kidney transplant patients, including cytokines IL1-β and IL-6. Downregulated genes were associated with B-cell and T-cell function, including CCR7 and CD27. Analysis of predicted transcription factor binding suggested an increase in proinflammatory transcription factor CCAAT/enhancer binding protein β-binding sites in older patients, whereas interferon regulatory factor 2 transcription factor binding sites were less prevalent.

CONCLUSIONS

Older kidney transplant recipients exhibited multiple differences in gene expression compared with younger patients, with upregulation of proinflammatory genes and downregulation of adaptive immune response genes. These findings may explain the mechanism of increased vulnerability to infection and malignancy observed in older transplant patients.

Association of Cold Ischemia Time With Acute Renal Transplant Rejection

BACKGROUND

Kidney transplantation holds much promise as a treatment of choice for patients with end-stage kidney disease. The impact of cold ischemia time (CIT) on acute renal transplant rejection (ARTR) remains to be fully studied in a large cohort of renal transplant patients.

METHODS

From the Organ Procurement and Transplantation Network database, we analyzed 63 798 deceased donor renal transplants performed between 2000 and 2010. We assessed the association between CIT and ARTR. We also evaluated the association between recipient age and ARTR.

RESULTS

Six thousand eight hundred two (11%) patients were clinically diagnosed with ARTR. Longer CIT was associated with an increased risk of ARTR. After multivariable adjustment, compared with recipients with CIT < 12 hours, the relative risk of ARTR was 1.13 (95% confidence interval, 1.04-1.23) in recipients with CIT ≥ 24 hours. The association of CIT and ARTR was more pronounced in patients undergoing retransplantation: compared with recipients with CIT less than 12 hours, the relative risk of ARTR was 1.66 (95% confidence interval, 1.01-2.73) in recipients with CIT of 24 hours or longer. Additionally, older age was associated with a decreased risk of ARTR. Compared with recipients aged 18 to 29 years, the relative risk of ARTR was 0.50 (95% confidence interval, 0.45-0.57) in recipients 60 years or older. Longer CIT was also associated with increased risk of death-censored graft loss. Compared with recipients with CIT less than 12 hours, the hazard ratio of death-censored graft loss was 1.22 (95% confidence interval, 1.14-1.30) in recipients with CIT of 24 hours or longer.

CONCLUSIONS

Prolonged CIT is associated with an increased risk of ARTR and death-censored graft loss. Older age was associated with a lower risk of ARTR.

Time of Cold Ischemia and Delayed Graft Function in a Cohort of Renal Transplant Patients in a Reference Center

There are many factors involved in the delayed graft function of a renal graft, with prolonged cold ischemia time being one of the most relevant. The aim of this study is to evaluate the relationship between the time of cold ischemia and the delayed graft function, and acute rejection and graft loss at 1 year of follow-up. A retrospective cohort of 347 renal transplant patients were evaluated during the years 2009-2013. The incidence of delayed graft function was 18.4% (n = 65). The cold ischemia time was an independent risk factor for delayed graft function (odds ratio [OR] 1.10, 95% confidence interval [CI] 1.04-1.16). By grouping the time of cold ischemia by intervals, the risk of delayed graft function was greater in the 12-18 hours group (OR 2.06, 95% CI 1.02-4.15) and in the >18 hours group (OR 3.38, 95% CI 1.57-7.27). The risk of acute rejection did not increase with longer cold ischemia (p = 0.69), and cold ischemia time was not a risk factor for renal graft loss at 1-year follow-up (hazard ratio 0.97, 95% CI 0.88-1.06). In conclusion the time of cold ischemia (>12 hours) in renal transplant recipients of optimal deceased donors increases the risk of delayed graft function; however, this does not negatively impact the results in acute rejection or graft loss in the first year of the transplant.

Effect of Age on Leukopenia Following Renal Transplantation at a Single Center

Introduction:

Leukopenia in renal transplant recipients occurs commonly within the first year following transplantation; however, literature on the effects of age on leukopenia is scarce.

Design:

A single-center, retrospective review was conducted on 141 recipients transplanted from January 2011 to December 2015. Transplant recipients were characterized by age <60 years (n = 94) or age 60 years and older (n = 47) for analysis.

Results:

A greater incidence of leukopenia was seen in the older cohort compared to the younger cohort (64% vs 55%). Of those patients who developed leukopenia, the older cohort (n = 30) had a higher incidence of hospitalization for leukopenia (30% vs 23%) but a lower incidence of hospitalization for infection (20% vs 25%) compared to the younger cohort (n = 52). Additionally, one month following mycophenolate mofetil (MMF) discontinuation, the older cohort had reduced recovery of their white blood cell count (+263.8% vs +272.5%) and experienced less recurrent leukopenic episodes (50% vs 67%) and rejection episodes (0% vs 22%) compared to the younger cohort, alluding to the need for less immunosuppression.

Conclusions:

Age at transplantation was not associated with the development of leukopenia; however, older patients had a higher incidence of leukopenia and hospitalization for leukopenia. Dose reduction or discontinuation of MMF should be considered in older kidney transplant recipients who develop leukopenia.

Analyses of the short- and long-term graft survival after kidney transplantation in Europe between 1986 and 2015

The evolution of kidney allograft survival remains insufficiently studied in the context of the changing donor and recipient demographics. Since European data are lacking we performed a cohort study (1986-2015) that, based on the Collaborative Transplant Study, included 108 787 recipients of brain-death kidney donors in 135 hospitals across 21 European countries. We analyzed the hazard rate of kidney failure after transplantation. Between 1986 and 1999, improvement in graft survival was more pronounced in the short term than in the long term: one-, five- and ten-year hazard rates after transplantation declined 64% (95% confidence interval, 61%-66%), 53% (49%-57%) and 45% (39%-50%), respectively. Between 2000 and 2015, hazard rates at one, five and ten years post-transplant declined respectively 22% (12-30%), 47% (36-56%) and 64% (45-76%). Improvement in graft survival in the first five years post-transplant was significantly less since 2000, while improvement after five years was comparable to before. During the 2000-2015 period improvement of graft survival was greater in the long than in the short term. These changes were independent of changing donor and recipient characteristics, and reflect the evolution in global kidney transplant management over the past decades. Unfortunately, after accounting for the evolution of donor and recipient characteristics, we found that short-term improvement in graft survival decreased since 2000, while long-term improvement remained unchanged in Europe. Thus, deceleration of short-term graft survival improvement in more recent years illustrates an unmet need for innovation.

Effect of Immunosuppression on Target Blood Immune Cells Within 1 Year After Lung Transplantation: Influence of Age on T Lymphocytes

Background

Lymphocytes are targeted by immunosuppressive therapy in solid organ transplantation and they influence allograft outcome.

Material/Methods

Peripheral blood lymphocyte subsets (PBLS) determined by flow cytometry during the first year post-transplant from patients who underwent a first lung transplantation in a French University Hospital between December 2011 and July 2013 were retrospectively analyzed according to recipient characteristics and allograft outcome.

Results

Fifty-seven recipients were enrolled and 890 PBLS were collected. T lymphocytes and NK cells were rapidly decreased, below normal range, from the first postoperative days. B cells decreased more gradually, remaining within normal range, with the lowest level reached after day 100. In multivariate analysis, greater T lymphopenia was found in older recipients (−414 [−709 to −119] cells/μL, p=0.007). According to the outcome, multivariate analysis evidenced lower levels of lymphocytes when bacterial and viral infection occurred (−177 [−310 to −44] cells/μL, p=0.009 and (−601 [−984 to −218] cells/μL, p=0.002, respectively), higher CD8+ T lymphocytes with BOS (+324 [+94 to +553] cells/μL, p=0.006), and higher leukocytes with restrictive allograft syndrome (+3770 [+418 to +7122] cells/μL, p=0.028).

Conclusions

Aging is associated in our cohort with more severe T lymphopenia after induction therapy for lung transplantation. The analysis of leukocytes and PBLS is associated with specific profile according to the allograft outcome.

Senescence in chronic allograft nephropathy

Despite increasing numbers of patients on dialysis, the numbers of renal transplants performed yearly have remained relatively static. During the last 50 years, there have been many advances in the pharmacology of prevention of organ rejection. However, most patients will suffer from a slow but steady decline in renal function leading to graft loss. The most common cause of long-term graft loss is chronic allograft nephropathy (CAN). Therefore, elucidating and understanding the mechanisms involved in CAN is crucial for achieving better posttransplant outcomes. It is thought that the development of epithelial to mesenchymal transition (EMT) in proximal tubules is one of the first steps towards CAN, and has been shown to be a result of cellular senescence. Cells undergoing senescence acquire a senescence associated secretory phenotype (SASP) leading to the production of interleukin-1 alpha (IL-1α), which has been implicated in several degenerative and inflammatory processes including renal disease. A central mediator in SASP activation is the production of reactive oxygen species (ROS), which are produced in response to numerous physiological and pathological stimuli. This review explores the connection between SASP and the development of EMT/CAN in an effort to suggest future directions for research leading to improved long-term graft outcomes.

Post-transplantation diabetes-state of the art

With increasing success in overcoming the immunological and infectious challenges accompanying solid organ transplantation, susceptibility to post-transplant diabetes and cardiovascular disease has assumed increasing importance. Although some guidance is available from diabetes-related literature pertaining to the general population, some aspects are unique to solid organ allograft recipients. Both insulin resistance and β-cell dysfunction are generally agreed to contribute to development and manifestation of post-transplant diabetes, but controversy continues about which is most important and to what extent post-transplant diabetes is a distinct entity or simply a variant of type 2 diabetes with transplant-specific components. The optimum method and timing for detection and diagnosis of post-transplant diabetes remains an area of uncertainty. However, the greatest needs are to: address the absence of contemporary data for incidence and clinical outcomes associated with post-transplant diabetes; establish the role of glycaemic control; and assess the role of new diabetic therapies in prevention and management of post-transplant diabetes. We place the present knowledge base in the context of other advances in transplantation, challenge some existing ideas, and examine the potential role of emerging diabetes therapies. In highlighting existing deficiencies, we hope to provide direction for future research that will ultimately reduce incidence and improve management of post-transplant diabetes.