Influence of HLA Matching on Survival in Heart Transplantation

Role of HLA matching and donor specific antibody development in long-term survival, acute rejection and cardiac allograft vasculopathy

Although there are different data supporting benefits of HLA matching in kidney transplantation, its role in heart transplantation is still unclear. HLA mismatch (MM) between donor and recipient can lead to the development of donor-specific antibodies (DSA) which produces negative events on the outcome of heart transplantation. Moreover, DSAs are involved in the development of antibody-mediated rejection (AMR) and are associated with an increase in cardiac allograft vasculopathy (CAV). In this study it is analyzed retrospectively the influence of HLA matching and anti-HLA antibodies on overall survival, AMR and CAV in heart transplantation. For this retrospective study are recruited heart transplanted patients at the Cardiac Transplantation Centre of Naples between 2000 and 2019. Among the 155 heart transplant patients, the mean number of HLA-A, B, -DR MM (0 to 6) between donor and recipient was 4.5 ± 1.1. The results show a negative association between MM HLA-DR and survival (p = 0.01). Comparison of patients with 0-1 MM at each locus to all others with 2 MM, for both HLA class I and class II, has not showed significant differences in the development of CAV. Our analysis detected DSA in 38.1% of patients. The production of de novo DSA reveals that there is not an influence on survival (p = 0.72) and/or AMR (p = 0.39). Instead, there is an association between the production of DSA class II and the probability of CAV development (p = 0.03). Mean fluorescence intensity (MFI) values were significantly higher in CAV-positive patients that CAV-negative patients (p = 0.02). Prospective studies are needed to evaluate HLA class II matching as an additional parameter for heart allocation, especially considering the increment of waiting list time.

Exploring personalized treatment for cardiac graft rejection based on a four-archetype analysis model and bioinformatics analysis

Heart transplantation is the gold standard for treating patients with advanced heart failure. Although improvements in immunosuppressive therapies have significantly reduced the frequency of cardiac graft rejection, the incidences of T cell-mediated rejection (TCMR) and antibody-mediated rejection remain almost unchanged. A four-archetype analysis (4AA) model, developed by Philip F. Halloran, illustrated this problem well. It provided a new dimension to improve the accuracy of diagnoses and an independent system for recalibrating the histology guidelines. However, this model was based on the invasive method of endocardial biopsy, which undoubtedly increased the postoperative risk of heart transplant patients. Currently, little is known regarding the associated genes and specific functions of the different phenotypes. We performed bioinformatics analysis (using machine-learning methods and the WGCNA algorithm) to screen for hub-specific genes related to different phenotypes, based Gene Expression Omnibus accession number GSE124897. More immune cell infiltration was observed with the ABMR, TCMR, and injury phenotypes than with the stable phenotype. Hub-specific genes for each of the four archetypes were verified successfully using an external test set (accession number GSE2596). Logistic-regression models based on TCMR-specific hub genes and common hub genes were constructed with accurate diagnostic utility (area under the curve > 0.95). RELA, NFKB1, and SOX14 were identified as transcription factors important for TCMR/injury phenotypes and common genes, respectively. Additionally, 11 Food and Drug Administration-approved drugs were chosen from the DrugBank Database for each four-archetype model. Tyrosine kinase inhibitors may be a promising new option for transplant rejection treatment. KRAS signaling in cardiac transplant rejection is worth further investigation. Our results showed that heart transplant rejection subtypes can be accurately diagnosed by detecting expression of the corresponding specific genes, thereby enabling precise treatment or medication.

Significance of HLA-matching and anti-HLA antibodies in heart transplant patients receiving induction therapy?

OBJECTIVES

Though Human Leukocyte Antigen (HLA) matching benefits are demonstrated in renal transplantation, evidence in heart transplantation is lacking, and its clinical feasibility is uncertain. Post-transplantation anti-HLA antibodies are being increasingly studied in organ transplantation, with diverging conclusions between transplantated organs.

METHODS

We analyzed retrospectively the influence of HLA matching and anti-HLA antibodies on overall survival, acute rejection and chronic allograft vasculopathy in 309 patients receiving induction therapy and triple-drug immunosuppression.

RESULTS

The average number of HLA-A/B/DR mismatches between donor and recipient was 4.9 ± 1. The majority of mismatches was for Class I HLA-A/B with an average of 3.3, then for Class I HLA-DR with an average of 1.6. Overall, the HLA-A/-B/-DR mismatches had no influence on the cardiac allograft survival (p = 0.28). However, HLA-DR mismatches were negatively correlated to severe cellular and/or humoral allograft rejection (p = 0.04). Our analysis found anti-HLA antibodies in 27% of recipients, de novo anti-HLA antibodies in 16% of recipients, and donor-specific anti-HLA (DSA) antibodies in 8% of recipients. Furthermore, de novo DSA had no influence on the 5-year survival (78% with DSA vs. 92% without DSA; p = 0.49), which may be masked by the limited number of recipients in analysis By univariable analysis, anti-HLA antibodies (preexisting or de novo) unrelated or related to the donor had no influence on severe cellular and/or humoral rejection or on chronic allograft vasculopathy.

CONCLUSIONS

HLA-DR mismatch was negatively correlated to severe cellular and/or humoral allograft rejection but had no influence on cardiac allograft survival. In this study, anti-HLA antibodies (preexisting or de novo) unrelated or related to the donor had no influence on cellular and/or humoral rejection or on chronic allograft vasculopathy. The results of this study add to the controversy on the impact of allo-antibodies in heart transplant recipients receiving induction therapy and contemporary immunosuppression.

Donor-recipient Matching in Heart Transplantation

Heart transplantation remains the treatment of choice for end-stage Heart Failure (HF). Due to the shortage of organs for transplantation and the occurrence of perioperative complications, a key problem is donor matching, which should result in increased survival and improved quality of life for patients. The success of this procedure depends on various parameters such as gender, weight, ABO blood group and Human Leukocyte Antigen (HLA) system of both the recipient and the donor. Furthermore, non-HLA antigens may also be valuable in donor-recipient matching. The aim of this article is to summarize the recent knowledge on the impact of various factors on accurate donor-recipient matching to heart transplantation.

Investigation of hub genes and immune status in heart transplant rejection using endomyocardial biopsies

T cell‒mediated rejection (TCMR) and antibody‐mediated rejection (ABMR) are severe post‐transplantation complications for heart transplantation (HTx), whose molecular and immunological pathogenesis remains unclear. In the present study, the mRNA microarray data set GSE124897 containing 645 stable, 52 TCMR and 144 ABMR endomyocardial biopsies was obtained to screen for differentially expressed genes (DEGs) between rejected and stable HTx samples and to investigate immune cell infiltration. Functional enrichment analyses indicated roles of the DEGs primarily in immune‐related mechanisms. Protein‐protein interaction networks were then constructed, and ICAM1, CD44, HLA‐A and HLA‐B were identified as hub genes using the maximal clique centrality method. Immune cell infiltration analysis revealed differences in adaptive and innate immune cell populations between TCMR, ABMR and stable HTx samples. Additionally, hub gene expression levels significantly correlated with the degree and composition of immune cell infiltration in HTx rejection samples. Furthermore, drug‐gene interactions were constructed, and 12 FDA‐approved drugs were predicted to target hub genes. Finally, an external GSE2596 data set was used to validate the expression of the hub genes, and ROC curves indicated all four hub genes had promising diagnostic value for HTx rejection. This study provides a comprehensive perspective of molecular and immunological regulatory mechanisms underlying HTx rejection.

Association of the Number of HLA-DR Mismatches With Early Post-transplant Acute Cellular Rejection Among Heart Transplantation Recipients: A Cohort Study in Japanese Population

BACKGROUND

Although many risk factors are reported about graft rejection after heart transplantation (HTx), the effect of HLA mismatch (MM) still remains unknown, especially in the Japanese population. The aim of the present study was to investigate the influence of HLA MM on graft rejection among HTx recipients in Japan.

METHODS

We retrospectively investigated the association of the number of HLA MM including class I (A, B) and class II (DR) (for each locus MM: 0 to 2, total MM: 0 to 6) and the incidence of moderate to severe acute cellular rejection (ACR) confirmed by endomyocardial biopsy (International Society for Heart and Lung Transplantation grade ≥ 3A/2R) within 1 year after HTx.

RESULTS

Between 2007 and 2014, we had 49 HTx cases in our institute. After excluding those with insufficient data and positive donor-specific antigen, finally 35 patients were enrolled. Moderate to severe ACR was observed in 16 (45.7%) patients. The number of HLA-DR MM was significantly associated with the development of ACR (ACR+: 1.50 ± 0.63, ACR-: 1.11 ± 0.46, P = .029). From univariate analysis, DR MM = 2 was the only independent risk factor for ACR episodes (P = .017). The frequency of ACR within 1 year was significantly higher in those with DR MM = 2 (DR MM = 0 to 1: 0.3 ± 0.47, DR MM = 2: 1.17 ± 1.34 times, P = .007).

CONCLUSIONS

The number of HLA-DR MMs was associated with the development and recurrence of ACR episodes among HTx recipients within 1 year after transplantation in Japanese population.

Human leukocyte antigens and alloimmunization in heart transplantation: an open debate

Considerable advances in heart transplantation outcome have been achieved through the improvement of donor-recipient selection, better organ preservation, lower rates of perioperative mortality and the use of innovative immunosuppressive protocols. Nevertheless, long-term survival is still influenced by late complications. We support the introduction of HLA matching as an additional criterion in the heart allocation. Indeed, allosensitization is an important factor affecting heart transplantation and the presence of anti-HLA antibodies causes an increased risk of antibody-mediated rejection and graft failure. On the other hand, the rate of heart-immunized patients awaiting transplantation is steadily increasing due to the limited availability of organs and an increased use of ventricular assist devices. Significant benefits may result from virtual crossmatch approach that prevents transplantation in the presence of unacceptable donor antigens. A combination of both virtual crossmatch and a tailored desensitization therapy could be a good compromise for a favorable outcome in highly sensitized patients. Here, we discuss the unresolved issue on the clinical immunology of heart transplantation.

The influence of human leukocyte antigen matching on outcomes in pediatric heart transplantation

Previous adult heart transplantation studies have demonstrated that donor-recipient human leukocyte antigen (HLA) matching results in reduced graft failure and improved patient survival. No study has examined these effects in children. This study investigated the effect of HLA matching on outcomes in pediatric heart transplantation. All pediatric heart transplantation data for patients 0-18 years of age available from the United Network for Organ Sharing Transplant Registry from 1987 to 2009 were analyzed retrospectively. Donor-recipient HLA matching at loci A, B, and DR (0-6) was compared with graft survival and recipient survival. For this study, 3,751 pediatric cardiac transplantation events with complete HLA matching data were identified and grouped as having 0 to 2 matches (3,416 events) or 3 to 6 matches (335 events). The 3- to 6-match group had less graft failure than the 0- to 2-match group (28.7% vs 34.4%; p = 0.035) and greater patient survival by 5 years (81% vs 72%; p = 0.045) and 10 years (66% vs 55%; p = 0.005) after transplantation. The HLA-DR matching alone resulted in less graft failure (p = 0.038) and improved patient survival (p = 0.017). A higher degree of HLA matching in pediatric heart transplantation is associated with decreased graft failure and improved patient survival. In this study, decreased graft failure rates and superior survival also were seen with DR matching alone.

Human leukocyte antigen matching in heart transplantation: systematic review and meta-analysis

Allocation of donors with regard to human leukocyte antigen (HLA) is controversial in heart transplantation. This paper is a systematic review and meta-analysis of the available evidence. PubMed, Embase, and the Cochrane Library were searched systematically for studies that addressed the effects of HLA matching on outcome after heart transplantation. Fifty-seven studies met the eligibility criteria. 34 studies had graft rejection as outcome, with 26 of the studies reporting a significant reduction in graft rejection with increasing degree of HLA matching. Thirteen of 18 articles that reported on graft failure found that it decreased significantly with increasing HLA match. Two multicenter studies and nine single-center studies provided sufficient data to provide summary estimates at 12 months. Pooled comparisons showed that graft survival increased with fewer HLA-DR mismatches [0-1 vs. 2 mismatches: risk ratio (RR) = 1.09 (95% confidence interval (CI): 1.01-1.19; P = 0.04)]. Having fewer HLA-DR mismatches (0-1 vs. 2) reduced the incidence of acute rejection [(RR = 0.81 (0.66-0.99; P = 0.04)]. Despite the considerable heterogeneity between studies, the short observation time, and older data, HLA matching improves graft survival in heart transplantation. Prospective HLA-DR matching is clinically feasible and should be considered as a major selection criterion.

Association of human leukocyte antigen donor-recipient matching and pediatric heart transplant graft survival

BACKGROUND

The effect of donor-recipient human leukocyte antigen (HLA) matching on outcomes remains relatively unexplored in pediatric patients. The objective of this study was to investigate the effects of donor-recipient HLA matching on graft survival in pediatric heart transplantation.

METHODS AND RESULTS

The UNOS (United Network for Organ Sharing) database was queried for heart transplants occurring between October 31, 1987, and December 31, 2012, in a recipient aged ≤17 years with ≥1 postoperative follow-up visit. Retransplants were excluded. Transplants were divided into 3 donor-recipient matching groups: no HLA matches (HLA-no), 1 or 2 HLA matches (HLA-low), and 3 to 6 HLA matches (HLA-high). Primary outcome was graft loss. Four thousand four hundred seventy-one heart transplants met the study inclusion criteria. High degree of donor-recipient HLA matching occurred infrequently: HLA-high (n=269; 6%) versus HLA-low (n=2683; 60%) versus HLA-no (n=1495; 34%). There were no differences between HLA matching groups in the frequency of coronary vasculopathy (P=0.19) or rejection in the first post-transplant year (P=0.76). Improved graft survival was associated with a greater degree of HLA donor-recipient matching: HLA-high median survival, 17.1 (95% confidence interval, 14.0-20.2) years; HLA-low median survival, 14.2 (13.1-15.4) years; and HLA-no median survival, 12.1 (10.9-13.3 years) years; P<0.01, log-rank test. In Cox-regression analysis, HLA matching was independently associated with decreased graft loss: HLA-low versus HLA-no hazard ratio, 0.86 (95% confidence interval, 0.74-0.99), P=0.04; HLA-high versus HLA-no, 0.62 (95% confidence interval, 0.43-0.90), P<0.01.

CONCLUSIONS

Decreased graft loss in pediatric heart transplantation was associated with a higher degree of donor-recipient HLA matching, although a difference in the frequency of early rejection or development of coronary artery vasculopathy was not seen.

Simple score to assess the risk of rejection after orthotopic heart transplantation

BACKGROUND

The aim of this study was to derive and validate a risk score for rejection after orthotopic heart transplantation.

METHODS AND RESULTS

The United Network for Organ Sharing registry was used to identify patients undergoing orthotopic heart transplantation between 1998 and 2008. A total of 14 265 eligible patients were randomly divided into derivation (80%; n=11 412) and validation (20%; n=2853) cohorts. The primary outcome was drug-treated rejection within 1 year of orthotopic heart transplantation. Covariates found to be associated (exploratory univariate P<0.2) with rejection were entered into a multivariable logistic regression model. Inclusion of each variable in the model was assessed by improvement in the McFadden pseudo-R(2), likelihood ratio test, and c index. A risk score was then generated through the use of relative magnitudes of the odds ratios from the derivation cohort, and its ability to predict rejection was tested independently in the validation cohort. A 13-point risk score incorporating 4 variables (age, race, sex, HLA matching) was created. The mean scores in the derivation and validation cohorts were 8.3±2.2 and 8.4±2.1, respectively. Predicted 1-year rejection rates based on the derivation cohort ranged from 16.2% (score=0) to 50.7% (score=13; P<0.001). In weighted regression analysis, there was a strong correlation between these predicted rates of rejection and actual, observed rejection rates in the validation cohort (r(2)=0.96, P<0.001). Logistic regression analysis also demonstrated a significant association (odds ratio, 1.13; P<0.001). The c index of the composite score was equivalent in both the derivation and validation cohorts (c=0.67).

CONCLUSIONS

This novel 13-point risk score is highly predictive of clinically significant rejection episodes within 1 year of orthotopic heart transplantation. It has potential utility in tailoring immunosuppressive regimens and in research stratification in orthotopic heart transplantation.

Outcomes in pediatric cardiac transplantation with a positive HLA cross-match

Previous studies have shown poor outcomes in pediatric heart transplant recipients with a high PRA or a positive direct donor-recipient cross-match. This study describes outcomes in patients with a positive cross-match at a large pediatric program. Pediatric heart transplant patients at a large single center between January 1993 and July 2009 were reviewed; those with cross-match data were analyzed. Cross-match data were available in 242/262 (92.4%) patients. Indications for transplant were cardiomyopathy (58%), CHD (32%), and retransplant (7%). PRA was ≥10% in 31/213 (14.6%) patients. A retrospective cross-match was positive in 17/31 (55%) patients with PRA ≥10% and 0/182 with PRA <10%. In positive cross-match patients, rejection frequency in the first year post-transplant was higher than negative cross-match patients (1.69 vs. 0.96 episodes/pt year, p = 0.014). There was no difference in rejection frequency after the first year post-transplant (0.18 vs. 0.12 episodes/pt year, p = 0.14). Overall survival was not significantly different between the groups with a median follow-up time of 4.5 yr. Heart transplantation in patients with a positive cross-match may result in good medium-term survival but a higher frequency of early rejection. Further investigation is warranted to define which patients with a positive cross-match will do poorly.