The impact of human leukocyte antigen matching on transplant complications and immunosuppression dosage

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

Association of HLA mismatch and MTOR inhibitor regimens with malignancy and mortality after kidney transplantation

Background The association of mammalian target of rapamycin inhibitors (MTORI) with malignancies and mortality in kidney transplant recipients (KTR) with different degrees of human leukocyte antigen mismatch (HLA-mm) at transplant has not been previously studied. Methods Our observational cohort study included 166, 256 adult KTRs in 2000-2018. Immunosuppression in the first post-transplant year were MTORIs in 13,056 (7.85%) and non-MTORIs in 153,200 (92.15%). We used Cox multivariable regression models to determine the cause-specific hazard ratio (HRcs) of non-melanoma skin cancer (NMSC),solid organ malignancies (SOM)] and all-cause death (death_ac); and the HR of the composite outcomes of NMSC or death_ac and SOM or death_ac associated with MTORI versus non-MTORI regimens in the overall study sample and the 0, 1-3, and 4-6 HLA-A, B and DR mm subgroups. Results NMSC risk was lower with MTORI than non-MTORI in all HLA-mm subgroups [(0 mm, HRcs = 0.67; 95% CI = 0.46-0.97, 1-3 mm, HRcs = 0.73; 95% CI = 0.61-0.87, 4-6 mm, HRcs = 0.69; 95% CI = 0.62-0.76)]. SOM risks were similar between regimens in the 0 HLA mm subgroup (HRcs = 1.10 (95% CI = 0.78-1.57) and lower with MTORI than non-MTORI in the 1-3, and 4-6 HLA-mm subgroups, [(HR = 0.84; (95% CI = 0.71-0.99), and (HR = 0.86; 95% CI = 0.78-0.94); respectively]. Risks of death_ac and composite outcomes (NMSC or death_ac and SOM or death_ac) were higher with MTORI than non-MTORI in almost all HLA-mm subgroups. Conclusion MTORIs are associated with protection from NMSC and SOM in almost all HLA-mm subgroups ca; however, their association with increased all-cause mortality in adult kidney transplant recipients needs further investigation.

Association of HLA Antigen Mismatch With Risk of Developing Skin Cancer After Solid-Organ Transplant

Importance

Risk factors for the development of skin cancer after solid-organ transplant can inform clinical care, but data on these risk factors are limited.

Objective

To study the association between HLA antigen mismatch and skin cancer incidence after solid-organ transplant.

Design, Setting, and Participants

This retrospective cohort study is a secondary analysis of the multicenter Transplant Skin Cancer Network study of 10 649 adults who underwent a primary solid-organ transplant between January 1, 2003, and December 31, 2003, or between January 1, 2008, and December 31, 2008. These participants were identified through the Scientific Registry of Transplant Recipients standard analysis files, which contain data collected mostly by the Organ Procurement and Transplantation Network. Participants were matched to skin cancer outcomes by medical record review. This study was conducted from August 1, 2016, to July 31, 2017.

Main Outcomes and Measures

The primary outcome was time to diagnosis of posttransplant skin cancer, including squamous cell carcinoma, melanoma, and Merkel cell carcinoma. The HLA antigen mismatch was calculated based on the 2016 Organ Procurement and Transplantation Network guidelines. Risk of skin cancer was analyzed using a multivariate Cox proportional hazards regression model.

Results

In total, 10 649 organ transplant recipients (6776 men [63.6%], with a mean [SD] age of 51 [12] years) contributed 59 923 years of follow-up. For each additional mismatched allele, a 7% to 8% reduction in skin cancer risk was found (adjusted hazard ratio [HR], 0.93; 95% CI, 0.87-0.99; P = .01). Subgroup analysis found the protective effect of HLA antigen mismatch to be statistically significant in lung (adjusted HR, 0.70; 95% CI, 0.56-0.87; P = .001) and heart (adjusted HR, 0.75; 95% CI, 0.60-0.93; P = .008) transplant recipients but not for recipients of liver, kidney, or pancreas. The degree of HLA-DR mismatch, but not HLA-A or HLA-B mismatch, was the most statistically significant for skin cancer risk (adjusted HR, 0.85; 95% CI, 0.74-0.97; P = .01).

Conclusions and Relevance

The HLA antigen mismatch appears to be associated with reductions in the risk of skin cancer after solid-organ transplant among heart and lung transplant recipients; this finding suggests that HLA antigen mismatch activates the tumor surveillance mechanisms that protect against skin cancer in transplant recipients and that skin cancer risk may be higher in patients who received a well-matched organ.

Living donor risk model for predicting kidney allograft and patient survival in an emerging economy

AIM

Living donor kidney is the main source of donor organs in low to middle income countries. We aimed to develop a living donor risk model that predicts graft and patient survival in an emerging economy.

METHODS

We used data from the Sindh Institute of Urology and Transplantation (SIUT) database (n = 2283 recipients and n = 2283 living kidney donors, transplanted between 1993 and 2009) and conducted Cox proportional hazard analyses to develop a composite score that predicts graft and patient survivals.

RESULTS

Donor factors age, creatinine clearance, nephron dose (estimated by donor/recipient body weight ratio) and human leukocyte antigen (HLA) match were included in the living donor risk model. The adjusted hazard ratios (HRs) for graft failures among those who received a kidney with living donor scores (reference to donor score of zero) of 1, 2, 3 and 4 were 1.14 (95%CI: 0.94-1.39), 1.24 (95%CI:1.03-1.49), 1.25 (95%CI:1.03-1.51) and 1.36 (95%CI:1.08-1.72) (P-value for trend =0.05). Similar findings were observed for patient survival.

CONCLUSIONS

Similar to findings in high income countries, our study suggests that donor characteristics such as age, nephron dose, creatinine clearance and HLA match are important factors that determine the long-term patient and graft survival in low income countries. However, other crucial but undefined factors may play a role in determining the overall risk of graft failure and mortality in living kidney donor transplant recipients.

Kidney Transplant Recipients With Primary Membranous Glomerulonephritis Have a Higher Risk of Acute Rejection Compared With Other Primary Glomerulonephritides

BACKGROUND

Despite being the leading cause of graft failure, there is a lack of published data about the rates of rejection in kidney transplant patients with glomerulonephritis as the cause of end-stage renal disease.

METHODS

We examined all consecutive adult (>18 years) renal transplant recipients with biopsy-proven native renal glomerular disease who underwent kidney transplant between 1994 and 2013. Glomerulonephritis groups included were IgA nephropathy (IgAN) (N = 306), focal segmental glomerulosclerosis (FSGS) (N = 298), membranous nephropathy (MN) (N = 81), and lupus nephritis (LN) (N = 177).

RESULTS

In the total cohort of 862 patients, 363 patients had an episode of acute rejection during the follow-up period of 19 years (incidence rate of 7.2% per year). Forty-five of 81 patients with MN had an episode of acute rejection during the follow-up period. Patients with MN had significantly higher incidence of acute rejection (12.1 per 100 person years, P < 0.05) in comparison to IgAN (7.2 per 100 person years), FSGS (7.4 per 100 person years), and LN (7.9 per 100 person years). Patients with MN had 1.9 times higher risk of developing acute rejection after transplant in comparison to IgAN (P < 0.005). In patients with MN, 33 of 45 (73.3%) rejection events were acute cellular rejection, 8 (17.8%) of 45 were acute antibody-mediated rejection and 6 of 45 (13.3%) were combined cellular and antibody-mediated acute rejection. Despite higher rates of acute rejection, 10-year allograft survival was similar in all subgroups.

CONCLUSIONS

Patients with MN have higher incidence of acute rejection after kidney transplant but have similar 10-year allograft survival in comparison to the other glomerular diseases like IgAN, FSGS, and LN.

Genetic predictors of long-term graft function in kidney and pancreas transplant patients

Kidney and pancreas transplantation have helped transform the lives of people with end-stage renal failure and individuals with type 1 diabetes who have poor glycaemic control/severe secondary complications, respectively. Despite an improvement in immunosuppressive regimes, operative techniques and decreased initial rejection rates, there has been little improvement in long-term graft survival rates over the past decade. Whilst limited progress has been made in establishing clinical markers of graft function, several genetic markers of long-term graft function have been identified. These genetic markers have the potential to (i) assist in selecting marginal donor organs for transplantation, (ii) provide better understanding of the mechanisms behind graft loss enabling identification of new, or repurposing, current treatments to extend graft function and (iii) provide a window of opportunity to identify and treat individuals before graft failure has occurred. This review will discuss the different genetic variants screened for a role in predicting transplant longevity, examine their findings and limitations and introduce where the future of genetic research within the transplantation field lies.

[Determination of HLA-A, -B and -DRB1 polymorphism in brain dead organ donors representative of the Colombian general population, 2007-2014]

INTRODUCTION

Genes encoding for human leukocyte antigens (HLA) are highly polymorphic and of great importance in organ transplantation procedures, as determining allelic frequencies in defined populations is taken into account among the scientific criteria for organ allocation.

OBJECTIVE

The objective of this study was to establish the antigen HLA-A, -B, and -DRB1 haplotype frequencies in organ donors representative of the Colombian population after brain death.

MATERIALS AND METHODS

We conducted a descriptive retrospective study involving 2,506 cadaveric organ donors including an allelic and haplotype analysis of HLA-A, -B and -DRB1; we also determined the Hardy-Weinberg equilibrium.

RESULTS

We identified 21, 43 and 15 allelic loci for groups A*, B* and DRB1*, respectively. We detected 1,268 HLA-A, -B and -DR, 409 HLA-A-B, 383 HLA-DR-B, and 218 HLA-A-DR haplotypes. The three loci were found to be in Hardy-Weinberg equilibrium between the number of heterozygotes observed and the expected number, with p values of ;0.05.

CONCLUSIONS

This study provides information on the allelic distribution of HLA class I and II in organ donors from the six regions in which Colombia is structurally divided to provide transplant services.

HLA-DRB1 and susceptibility to kidney allograft rejection in Southern Iranian patients

Kidney transplantation is the best treatment option for the patients with end-stage renal disease. Viral infections and genetic factors such as HLA-II antigens may affect the kidney transplant outcome. The compatibility of HLA-DRB1 molecules in the survival of kidney transplant is important. Also, the correlation between these molecules and viral infections is significant. The current study investigates the allele frequency of HLA-DRB1 in 41 recipient kidney transplant and 203 normal healthy controls by polymerase chain reaction using sequence specific primers. Moreover the relation between HLA-DRB1 allelic groups and hepatitis B, hepatitis C and cytomegalovirus viral infections was also studied. However statistical analysis of the allele frequencies didn't show any significant association between HLA-DRB1 allelic group distributions or sharing and susceptibility to acute kidney transplant rejection (P > 0.05). Comparing the allele frequencies between HLA-DRB1*14 and DRB1*04 allelic showed a significant difference in controls and patients (P = 0.03 and P = 0.05 respectively). The results of the present study also showed a significant association between possession of HLA-DRB1*07 allele in kidney transplant recipients and hepatitis C virus infection (P = 0.009). In conclusion however the results of the present study did not showed relation between HLA-DRB1 allele's frequencies or sharing and kidney transplantation outcome, the results indicated that HLA-DRB1 alleles may susceptible individuals to renal disease or play a role in susceptibility to viral infection in kidney transplant patients.

A more efficient method to generate integration-free human iPS cells

We report a simple method, using p53 suppression and nontransforming L-Myc, to generate human induced pluripotent stem cells (iPSCs) with episomal plasmid vectors. We generated human iPSCs from multiple donors, including two putative human leukocyte antigen (HLA)-homozygous donors who match ∼20% of the Japanese population at major HLA loci; most iPSCs are integrated transgene-free. This method may provide iPSCs suitable for autologous and allologous stem-cell therapy in the future.

[Rejection of kidney graft: mechanism and prevention]

Rejection occurs after the introduction of a genetically different graft, in a recipient. Nowadays, it is still a major obstacle in renal transplantation and reflects a normal protective immune response of a recipient against a foreign antigen. Involving many mechanisms of the innate and adaptive immunity, this reaction results in renal parenchymal lesions witch may progress to graft destruction and loss of its function. Several ways are currently used to reduce the action of the immune system and consequently reduce the risk of rejection. After a presentation of the main actors and the sequence of events leading to rejection, we will describe the strategy used by antirejection teams' transplantation. We will successively consider the prevention (pre-transplant immunological assessment, preventive immunosuppressive therapy), the monitoring (search for antibodies, biopsies) and the treatment.

Subgroup analyses in randomized controlled trials: the need for risk stratification in kidney transplantation

Although randomized controlled trials (RCT) are the gold standard for establishing causation in clinical research, their aggregated results can be misleading when applied to individual patients. A treatment may be beneficial in some patients, but its harms may outweigh benefits in others. While conventional one-variable-at-a-time subgroup analyses have well-known limitations, multivariable risk-based analyses can help uncover clinically significant heterogeneity in treatment effects that may be otherwise obscured. Trials in kidney transplantation have yielded the finding that a reduction in acute rejection does not translate into a similar benefit in prolonging graft survival and improving graft function. This paradox might be explained by the variation in risk for acute rejection among included kidney transplant recipients varying the likelihood of benefit or harm from intense immunosuppressive regimens. Analyses that stratify patients by their immunological risk may resolve these otherwise puzzling results. Reliable risk models should be developed to investigate benefits and harms in rationally designed risk-based subgroups of patients in existing RCT data sets. These risk strata would need to be validated in future prospective clinical trials examining long-term effects on patient and graft survival. This approach may allow better individualized treatment choices for kidney transplant recipients.

Monozygotic transplantation: concerns and opportunities

We describe the case of a 24-year-old female with end-stage renal disease from focal segmental glomerulosclerosis (FSGS) diagnosed at age 16, who underwent monozygotic triplet transplantation at age 21 from her sister. Monozygosity was established by buccal smear DNA PCR amplification using short tandem repeat (1) profiling for 16 genetic alleles. All immunosuppression was discontinued by 1 month posttransplant. To evaluate the use of immunosuppression in HLA identical monozygotic transplantation, we interrogated the OPTN (Organ Procurement Transplant Network) database for all transplants conducted from 1987 to 2006. We identified 194 probable identical twin transplantations based on age, gender, race, ethnic category, blood type and HLA match. We evaluated the use of various immunosuppressive agents at discharge, 6 months and 1, 2 and 3 years after transplantation. Seventy-one percent of these patients at discharge and 34% at the end of 1 year were on immunosuppression. At discharge 61% received steroids and 30% received calcineurin inhibitors and 66% of these remained on calcineurin inhibitors at 1 year. Renal function was superior among those not maintained on immunosuppression. Thus, monozygotic transplantation confers an immunologic advantage that allows immunosuppression elimination despite a risk of recurrent glomerular disease such as FSGS with appropriate evaluation and management.