Immunological risk in recipients of kidney transplants from extended criteria donors

T-cell Subset Profile in Kidney Recipients of Extended or Standard Donors

INTRODUCTION

The usage of extended-criteria donors (ECD) became a routinely accepted manner in the last decade. ECD is a potential risk factor for antibody-mediated rejection. Analysis of lymphocyte subsets might be a complementary diagnostic toolkit because there is limited knowledge about this term.

METHOD

Between May 12, 2016, and September 4, 2019, a total of 130 patients who had undergone kidney transplant were investigated. Patients were divided in ECD and standard criteria donor (SCD) groups. Blood samples were collected before the operation, then in the first week and after 30, 60, 180, and 365 days. Besides routine laboratory tests, multicolor flow cytometry was performed for lymphocyte subsets.

RESULTS

ECD grafts were transplanted to older recipients. The number of CD4+ cells increased in the SCDs from the first week to until the end of first month, and then decreased. The number of CD4+ cells decreased from the beginning of the study until the end of first year to 66% of its original value in ECDs. At the first month, the number of CD19+ cells was higher in SCD compared with ECD cases; the number then decreased in both groups. T-regulatory cells had a drop at the first week that lasted until the first month. A bigger increase in SCD and a moderate increase in ECD group were then observed. The kinetics of CD19+ and CD19+ naive cells are similar in the ECD and SCD groups. In the SCD group, cell count decreased in both CD19+ (13%) and CD19+ naive (12%) between third and sixth month. The count of CD19+ cells decreased by 9%, but the count of CD19+ naive cells increased by 11% between the sixth month and first year.

DISCUSSION

The prolonged postoperative uremic state caused by the poorer initial function, together with an aging immune system, explains the weaker immune response in ECD patients, which may be the cause of the decreased number of memory and regulatory T cells. Older patients with an ECD graft need a tailored, personalized, and less aggressive immunosuppressive treatment.

Expanded criteria donors in deceased donor kidney transplantation - An Asian perspective

There is an increasing gulf between demand and supply for kidneys in end-stage renal failure patients worldwide, especially Asia. Renal transplantation is often the treatment of choice for long-suffering patients who have to undergo dialysis on a regular basis. The utilization of expanded criteria donors (ECDs) to address the donor pool shortage has been proven to be a legitimate solution. Metzger first described the classification of standard criteria donor and ECD in 2002. Since then, the criterion has undergone various modifications, with the key aims of optimizing organ procurement rate while minimizing discard and rejection rates. We review the methods to improve selection, characterization of risks, and surgical techniques. Although the ECD kidneys have a higher risk of impaired donor and recipient outcome than the "standard criteria" transplants, it may be justified by the improved overall survival of these patients compared to those who remained on dialysis. It is, therefore, crucial that we perform meticulous selection, along with state of the art surgical techniques to maximize the use of this scarce resource. In this article, we review the pre-procurement and post-procurement processes implemented to preserve outcomes.

Strategies for an Expanded Use of Kidneys From Elderly Donors

The old-for-old allocation policy used for kidney transplantation (KT) has confirmed the survival benefit compared to remaining listed on dialysis. Shortage of standard donors has stimulated the development of strategies aimed to expand acceptance criteria, particularly of kidneys from elderly donors. We have systematically reviewed the literature on those different strategies. In addition to the review of outcomes of expanded criteria donor or advanced age kidneys, we assessed the value of the Kidney Donor Profile Index policy, preimplantation biopsy, dual KT, machine perfusion and special immunosuppressive protocols. Survival and functional outcomes achieved with expanded criteria donor, high Kidney Donor Profile Index or advanced age kidneys are poorer than those with standard ones. Outcomes using advanced age brain-dead or cardiac-dead donor kidneys are similar. Preimplantation biopsies and related scores have been useful to predict function, but their applicability to transplant or refuse a kidney graft has probably been overestimated. Machine perfusion techniques have decreased delayed graft function and could improve graft survival. Investing 2 kidneys in 1 recipient does not make sense when a single KT would be enough, particularly in elderly recipients. Tailored immunosuppression when transplanting an old kidney may be useful, but no formal trials are available.Old donors constitute an enormous source of useful kidneys, but their retrieval in many countries is infrequent. The assumption of limited but precious functional expectancy for an old kidney and substantial reduction of discard rates should be generalized to mitigate these limitations.

[Deceased donation in renal transplantation]

OBJECTIVES

To review epidemiologic data's and medical results of deceased donation in renal transplantation.

MATERIAL AND METHODS

Relevant publications were identified through Medline (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com) database using the following keywords, alone or in association, "brain death; cardiac arrest; deceased donation; organ procurement; transplantation". Articles were selected according to methods, language of publication and relevance. The reference lists were used to identify additional historical studies of interest. Both prospective and retrospective series, in French and English, as well as review articles and recommendations were selected. In addition, French national transplant and health agencies (http://www.agence-biomedecine.fr and http://www.has-sante.fr) databases were screened using identical keywords. A total of 2498 articles, 8 official reports and 17 newspaper articles were identified; after careful selection 157 publications were eligible for our review.

RESULTS

Deceased donation may involve either brain death or non-heartbeating donors (NHBD). Organ shortage led to the procurement of organs from expanded-criteria donors, with an increased age at donation and extended vascular disease, leading to inferior results after transplantation and underlining the need for careful donor management during brain death or cardiac arrest. Evolution of French legislation covering bioethics allowed procurement from Maastricht categories II and recently III non-heartbeating donors.

CONCLUSION

The increase of organ shortage emphasizes the need for a rigorous surgical technique during procurement to avoid loss of transplants. A history or current neoplasm in deceased-donors, requires attention to increase the pool of organs without putting the recipients at risk for cancer transmission. French NHBD program, especially from Maastricht category III, may stand for a potential source of valuable organs.

Renal transplantation with expanded criteria donors: Which is the optimal immunosuppression?

The growing gap between demand and supply for kidney transplants has led to renewed interest in the use of expanded criteria donor (ECD) kidneys in an effort to increase the donor pool. Although most studies of ECD kidney transplantation confirm lower allograft survival rates and, generally, worse outcomes than standard criteria donor kidneys, recipients of ECD kidneys generally have improved survival compared with wait-listed dialysis patients, thus encouraging the pursuit of this type of kidney transplantation. The relative benefits of transplantation using kidneys from ECDs are dependent on patient characteristics and the waiting time on dialysis. Because of the increased risk of poor graft function, calcineurin inhibitor (CNI)-induced nephrotoxicity, increased incidence of infections, cardiovascular risk, and malignancies, elderly recipients of an ECD kidney transplant are a special population that requires a tailored immunosuppressive regimen. Recipients of ECD kidneys often are excluded from transplant trials and, therefore, the optimal induction and maintenance immunosuppressive regimen for them is not known. Approaches are largely center specific and based upon expert opinion. Some data suggest that antithymocyte globulin might be the preferred induction agent for elderly recipients of ECD kidneys. Maintenance regimens that spare CNIs have been advocated, especially for older recipients of ECD kidneys. CNI-free regimens are not universally accepted due to occasionally high rejection rates. However, reduced CNI exposure and CNI-free regimens based on mammalian target of rapamycin inhibitors have shown acceptable outcomes in appropriately selected ECD transplant recipients.

Aging has small effects on initial ischemic acute kidney injury development despite changing intrarenal immunologic micromilieu in mice

Inflammatory process mediated by innate and adaptive immune systems is a major pathogenic mechanism of renal ischemia-reperfusion injury (IRI). There are concerns that organ recipients may be at increased risk of developing IRI after receiving kidneys from elder donors. To reveal the effects of aging on the development of renal IRI, we compared the immunologic micromilieu of normal and postischemic kidneys from mice of three different ages (9 wk, 6 mo, and 12 mo). There was a higher number of total T cells, especially effector memory CD4/CD8 T cells, and regulatory T cells in the normal kidneys of old mice. On day 2 after IRI, the proportion of necrotic tubules and renal functional changes were comparable between groups although old mice had a higher proportion of damaged tubule compared with young mice. More T cells, but less B cells, trafficked into the postischemic kidneys of old mice. The infiltration of NK T cells was similar across the groups. Macrophages and neutrophils were comparable between groups in both normal kidneys and postischemic kidneys. The intrarenal expressions of TNF-α and VEGF were decreased in normal and postischemic kidneys of aged mice. These mixed effects of aging on lymphocytes and cytokines/chemokines were not different between the two groups of old mice. Our study demonstrates that aging alters the intrarenal micromilieu but has small effects on the development of initial renal injury after IRI. Further study investigating aging-dependent differences in the repair process of renal IRI may be required.

Comparison of survival outcomes between Expanded Criteria Donor and Standard Criteria Donor kidney transplant recipients: a systematic review and meta-analysis

In 2002, the United Network for Organ Sharing proposed increasing the pool of donor kidneys to include Expanded Criteria Donor (ECD). Outside the USA, the ECD definition remains the one used without questioning whether such a graft allocation criterion is valid worldwide. We performed a meta-analysis to quantify the differences between ECD and Standard Criteria Donor (SCD) transplants. We paid particular attention to select studies in which the methodology was appropriate and we took into consideration the geographical area. Thirty-two publications were included. Only five studies, all from the USA, reported confounder-adjusted hazard ratios comparing the survival outcomes between ECD and SCD kidney transplant recipients. These five studies confirmed that ECD recipients seemed to have poorer prognosis. From 29 studies reporting appropriate survival curves, we estimated the 5-year pooled nonadjusted survivals for ECD and SCD recipients. The relative differences between the two groups were lower in Europe than in North America, particularly for death-censored graft failure. It is of primary importance to propose appropriate studies for external validation of the ECD criteria in non-US kidney transplant recipients.

Belatacept utilization recommendations: an expert position

INTRODUCTION

There is a continuing need for an immunosuppressive therapy that offers a high benefit-risk profile for renal transplant recipients, supporting long-term patient and graft survival while minimizing cumulative nephrotoxicity and other side effects. Belatacept , the first biological agent developed for primary maintenance immunosuppression, was recently approved for use in Europe. Belatacept combined with corticosteroids and a mycophenolic acid is indicated for prophylaxis of graft rejection in adults receiving renal transplant. Its use is contraindicated in Epstein-Barr virus seronegative or serostatus unknown patients due to increased risk of developing posttransplant lymphoproliferative disorder.

AREAS COVERED

This review provides practical recommendations for the use of belatacept, based on safety and efficacy data from Phase II and Phase III clinical trials in de novo kidney transplant recipients.

EXPERT OPINION

Treatment with belatacept is associated with improved long-term graft function, making belatacept an important option for prevention of kidney allograft rejection. Furthermore, efficacy and safety data over several years of therapy suggest that belatacept is particularly suitable for long-term immunosuppression, and the selective targeting offered by belatacept may help avoid some of the non-specific chronic safety risks associated with calcineurin inhibitors and steroids. Future studies will clarify the optimal regimen for belatacept usage.