Evaluation of published single nucleotide polymorphisms associated with acute GVHD

Effect of IL-2 polymorphism rs2069762 on single-unit cord blood transplant outcomes

BACKGROUND

Interleukin-2 (IL-2) is one of the most important cytokines that regulate the activation and proliferation of T cells and natural killer cells. The production of IL-2 may be affected by polymorphisms in the promoter region of the IL-2 gene (rs2069762). In allogeneic hematopoietic cell transplantation (HCT) from adult donors, rs2069762 has been associated with the incidence of acute and chronic graft-versus-host disease (GVHD). However, the impacts of IL-2 polymorphism on cord blood transplantation (CBT) outcomes remain unclear.

OBJECTIVE

The objective of this study was to assess the impact of IL-2 polymorphism rs2069762 on transplant outcomes, such as hematopoietic recovery, GVHD, overall survival, relapse, and non-relapse mortality (NRM) after CBT.

STUDY DESIGN

We conducted a retrospective analysis of data from adult patients who underwent single-unit CBT at our institution from November 2005 to March 2023 for whom DNA samples from recipients and donors were available. IL-2 genotyping was performed using real-time polymerase chain reaction with the TaqMan® SNP genotyping assay for rs2069762.

RESULTS

A total of 143 recipient and donor pairs were included in this study. The proportion of recipient IL-2 polymorphism rs2069762 was 48 % (n = 69) for AA, 42 % (n = 60) for CA, and 10 % (n = 14) for CC. The proportion of donor IL-2 polymorphism rs2069762 was 43 % (n = 61) for AA, 48 % (n = 69) for CA, and 9 % (n = 13) for CC. In the multivariate analysis, the use of an rs2069762 CA + CC donor was associated with lower neutrophil recovery compared to an rs2069762 AA donor (hazard ratio [HR], 0.66; 95 % confidence interval [CI], 0.50-0.88; P = 0.004). Furthermore, recipients of rs2069762 CA + CC were associated with higher NRM compared to recipients of rs2069762 AA (HR, 2.32; 95 % CI, 1.01-5.34; P = 0.047). Serum IL-2 levels at 8 weeks were significantly higher in rs2069762 CA + CC recipients compared to those with rs2069762 AA recipients (P = 0.014).

CONCLUSION

Our data showed that donor IL-2 polymorphism affects neutrophil recovery and recipient IL-2 polymorphism affects NRM in adults undergoing single-unit CBT. The polymorphism of IL-2 rs2069762 in recipients and donors might be associated with the clinical outcomes of single-unit CBT.

Interleukin-10 GCC/GCC haplotype is associated high risk of acute GVHD in patients undergoing allogeneic HSCT in the southern of Brazil

INTRODUCTION

Hematopoietic Stem Cell Transplant (HSCT) is currently an important curative treatment for many patients with malignant and non-malignant diseases. Graft versus host disease (GVHD) represents a major complication in allogeneic HSCT recipients. Several polymorphisms in cytokine genes have recently been investigated as candidates for risk factors for acute-GVHD (aGVHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT).

OBJECTIVE

In this study, we analyzed specific interleukin (IL)-10 haplotypes polymorphisms, in a cohort of 99 patients and their respective allo-HSCT donors for aGVHD and risk.

RESULTS

An association was found between IL-10 promoter haplotype polymorphisms at positions -1082, -819 and - 592 with the occurrence of aGVHD. Patients who have the GCC/GCC haplotype are at increased risk of aGVHD (P = 0.017, HR: 5.42 (95% CI: 1.34-21.84). In the donors group and severity of aGVHD as not found statistical significancy.

CONCLUSION

The results obtained show the IL-10 GCC/GCC haplotype can be an important biomarker to identify the greatest risk of aGVHD in the patient undergoing HSCT.

Lower overall survival in male patients with advanced disease undergoing allogeneic hematopoietic stem cell transplantation is associated with CYP1B1 Leu432Val polymorphism

Human cytochrome P450 1B1 (CYP1B1) is an extrahepatic key enzyme involved in estrogen metabolism, steroid synthesis, and pro-carcinogen activation. In a single-center retrospective study, 382 patients who underwent allogeneic hematopoetic stem cell transplantation and their donors were genotyped for CYP1B1 C432G polymorphism by reverse transcription polymerase chain reaction. One hundred and sixty-nine patients (44%) were homozygous wild-type (wt) gene CC, 157 (41%) heterozygous CG and 56 (15%) homozygous gene mutated GG. Of interest, mutated CYP1B1 was more common in male (62%) than in female patients (48%) P=0.006, unlike in donors. Five-year estimate for overall survival (OS) was 58±4% (CC) versus 48±3% (CG and GG), P=0.048. Surprisingly, this difference was only evident in males (P=0.024): OS 58±6% versus 42±4%, whereas it was virtually absent in females. Importantly, this difference was only evident in male patients with advanced disease (AD) (n=118, P=0.002): OS 44±8% (CC) versus 32±6% (CG) versus 6±6% (GG), whereas it was virtually absent in male patients with early disease. One-year non-relapse mortality in male patients with AD was 8±4% (CC) versus 21±5% (CG) versus 50±12% (GG), P=0.002. Three-year relapse rate in male patients with AD was 31±7% (wt) versus 42±6% (mut), P=0.04. Multivariate analysis for OS in male patients with AD revealed CYP1B1 polymorphism as the only prognostic factor: RR 1.78, P=0.001. In conclusion, these results suggest that male patients with AD and mutant CYP1B1 polymorphism have lower OS after allogeneic hematopoetic stem cell transplantation due to a higher non-relapse mortality and a higher relapse rate.

A genome-wide association study on hematopoietic stem cell transplantation reveals novel genomic loci associated with transplant outcomes

Introduction

Data on genomic susceptibility for adverse outcomes after hematopoietic stem cell transplantation (HSCT) for recipients are scarce.

Methods

We performed a genome wide association study (GWAS) to identify genes associated with survival/mortality, relapse, and severe graft-versus-host disease (sGvHD), fitting proportional hazard and subdistributional models to data of n=1,392 recipients of European ancestry from three centres.

Results

The single nucleotide polymorphism (SNP) rs17154454, intronic to the neuronal growth guidant semaphorin 3C gene (SEMA3C), was genome-wide significantly associated with event-free survival (p=7.0x10-8) and sGvHD (p=7.5x10-8). Further associations were detected for SNPs in the Paxillin gene (PXN) with death without prior relapse or sGvHD, as well as for SNPs of the Plasmacytoma Variant Translocation 1 gene (PVT1, a long non-coding RNA gene), the Melanocortin 5 Receptor (MC5R) gene and the WW Domain Containing Oxidoreductase gene (WWOX), all associated with the occurrence of sGvHD. Functional considerations support the observed associations.

Discussion

Thus, new genes were identified, potentially influencing the outcome of HSCT.

Donor Genetic Predisposition to High Interleukin-10 Production Appears Protective against Acute Graft-Versus-Host Disease

The persistence of graft-versus-host disease (GVHD) as the principal complication of allogeneic hematopoietic cell transplantation (HCT) demonstrates that HLA matching alone is insufficient to prevent alloreactivity. We performed molecular and functional characterization of 22 candidate cytokine genes for their potential to improve matching in 315 myeloablative, 10/10 HLA-matched donor−recipient pairs. Recipients of a graft carrying the -1082GG IL10 gene promoter region variant had a three-fold lower incidence of grade II−IV acute GVHD compared to IL10-1082AA graft recipients (SHR = 0.25, p = 0.005). This was most evident in matched unrelated donor (MUD) transplants, where the greatest alloreactivity is expected. IL10-1082GG transplants did not experience an increased incidence of relapse, and, consequently, overall survival was two-fold higher in IL10-1082GG MUD transplants (HR = 0.17, p = 0.023). Longitudinal post-transplant measurements demonstrated that -1082GG is a high-IL10-producing and -expressing genotype with attenuated CD8+ T-cell reconstitution. High post-transplant donor chimerism in T- and myeloid-cells (>95%) confirmed a predominant donor, rather than recipient, genotype effect on immune function and aGVHD. To date, this is the first study to report corroborating genome-to-cellular evidence for a non-HLA donor immunogenetic variant that appears to be protective against GVHD. The incorporation of IL10 variants in donor selection criteria and clinical-management decisions has the potential to improve patient outcomes.

Recipient and donor PTX3 rs2305619 polymorphisms increase the susceptibility to invasive fungal disease following haploidentical stem cell transplantation: a prospective study

Background

Invasive fungal disease (IFD) is a severe complication after haploidentical stem cell transplantation (haplo-HSCT) and has a poor prognosis. It has been shown that genetic polymorphism may be one possible reason for the increased risk of IFD. This study aimed to assess the role of genetic polymorphism in the level of susceptibility to IFD after haplo-HSCT.

Methods

In this study, we prospectively enrolled 251 patients who received haplo-HSCT at the Peking University Institute of Hematology from 2016 to 2018. Forty-three single nucleotide polymorphisms (SNPs) of the genomic DNA were genotyped in blood samples from both recipient and donor.

Results

Twenty-two patients (8.8%) were diagnosed with proven or probable IFD. The independent risk factors for IFD were grades 3–4 acute graft-versus-host disease, cytomegalovirus reactivation, and recipient and donor rs2305619 (PTX3) (P < 0.05) in multivariate analysis. Meanwhile, we combined the variables to develop the IFD risk scoring system and stratified patients into low- (0–2) and high-risk (3–4) groups. The 30-day and 100-day cumulative incidence of IFD in the low- and high-risk groups were 2.1% and 10.2%, 4.2% and 20.3%, respectively (P = 0.015).

Conclusions

PTX3 rs2305619 polymorphism increase the susceptibility of IFD after haplo-HSCT in the Chinese Han population, and the IFD scoring system could be useful in risk stratification for IFD after HSCT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07298-2.

Decreased Plasma Level of Cytokeratin 20 (KRT20) Is Indicative of the Emergence and Severity of Acute GvHD Irrespective to the Type of Organ Involvement

Accurate risk prediction of acute graft versus host disease (aGvHD) is currently an unmet clinical need. This study sought to analyze whether three plasma proteins expressed in a largely skin- and gut-restricted manner would be affected by the development of acute cutaneous and gastrointestinal aGvHD. The diagnostic sensitivity, specificity, and prognostic value of plasma cytokeratin-15 (KRT15) cytokeratin-20 (KRT20), and occludin (OCLN) were evaluated in a discovery and a validation cohort using ELISA in comparison with elafin (PI3) and regenerating family member 3 alpha (REG3A), two established markers of skin- and gut aGvHD. The discovery cohort (n = 39) revealed that at the time of diagnosis, plasma KRT20 showed a progressive decrease from unaffected individuals to patients with single-, and patients with multi-organ aGvHD. KRT20 was affected by cutaneous (p = 0.0263) and gastrointestinal aGvHD (p = 0.0242) independently and in an additive manner. Sensitivity and specificity of KRT20 for aGvHD involving both target organs (AUC = 0.852) were comparable to that of PI3 for skin-aGvHD (AUC = 0.708) or that of REG3A for gut-aGvHD (AUC = 0.855). Patient follow-up in the validation cohort (n = 67) corroborated these observations (p < 0.001), and linked low KRT20 to grade 2+ disease (p < 0.001), but failed to confirm low KRT20 as an independent risk factor. These data established a link between low plasma KRT20 levels and moderate to severe aGvHD involving multiple target organs.

Genetic Associations with Immune-mediated Outcomes after Allogeneic Hematopoietic Cell Transplantation

A recipient variant correlated with DPB1 expression is associated with the risks of GVHD and relapse after unrelated HCT.

Larger cohorts would be needed to detect other genotypic associations with aGVHD, cGVHD, and relapse after allogeneic HCT.

Previous studies have identified more than 200 genetic variants associated with acute or chronic graft-versus-host disease (aGVHD; cGVHD) or recurrent malignancy after allogeneic hematopoietic cell transplantation (HCT). We tested these candidate donor and recipient variants in a cohort of 4270 HCT recipients of European ancestry and in subcohorts of 1827 sibling and 1447 unrelated recipients who had 10/10 HLA-A, B, C, DRB1, and DQB1-matched donors. We also carried out a genome-wide association study (GWAS) for these same outcomes. The discovery and replication analysis of candidate variants identified a group of closely linked recipient HLA-DPB1 single-nucleotide polymorphisms (SNPs) associated with an increased risk of aGVHD and a corresponding decreased risk of recurrent malignancy after unrelated HCT. These results reflect a correlation with the level of HLA-DPB1 expression previously shown to affect the risks of aGVHD and relapse in unrelated recipients. Our GWAS identified an association of cGVHD with a locus of X-linked recipient intron variants in NHS, a gene that regulates actin remodeling and cell morphology. Evaluation of this association in a second replication cohort did not confirm the original replication results, and we did not reach any definitive conclusion regarding the validity of this discovery. The cohort used for our study is larger than those used in most previous HCT studies but is smaller than those typically used for other genotype-phenotype association studies. Genomic and disease data from our study are available for further analysis in combination with data from other cohorts.

A biomarker-guided, prospective, phase 2 trial of pre-emptive graft-versus-host disease therapy using anti-thymocyte globulin

BACKGROUND AIMS

Intensified immunosuppressive prophylaxis for graft-versus-host disease (GVHD) may be toxic and therefore warranted only in patients at high risk of developing GVHD. In patients who underwent allogeneic hematopoietic cell transplant at the authors' center, high serum soluble IL-2 receptor alpha (sIL-2Rα) and low IL-15 levels on day 7 post-transplant were found to predict a high risk of developing clinically significant GVHD (sGVHD), defined as grade 2-4 acute GVHD or moderate to severe chronic GVHD.

METHODS

This was a prospective, phase 2 trial in which high-risk patients (serum sIL-2Rα >4500 ng/L or IL-15 <31 ng/L) received rabbit anti-thymocyte globulin (ATG) 3 mg/kg on day 8 post-transplant. Controls consisted of patients who had their sIL-2Rα/IL-15 levels measured but did not participate in the trial. A total of 68 trial patients and 143 controls were accrued to this study. The primary endpoint was incidence of sGVHD.

RESULTS

There was a reduction in sGVHD in high-risk trial patients (received day 8 ATG) compared with high-risk controls (did not receive day 8 ATG) (sub-hazard ratio [SHR] = 0.48, P < 0.05). There was no significant difference between the groups in overall survival or relapse; however, there was a greater incidence of non-GVHD-associated non-relapse mortality in high-risk trial patients (SHR = 3.73, P < 0.05), mostly related to infections. This may be due in part to the biomarkers ineffectively stratifying GVHD risk.

CONCLUSIONS

Pre-emptive ATG therapy is both feasible and effective at reducing sGVHD without increasing relapse. Further mitigation strategies are needed to reduce the risk of infection associated with intensified GVHD prophylaxis. This study was registered at ClinicalTrials.gov (NCT01994824).

Genetic Polymorphisms of Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) and clinical outcomes post-allogeneic hematopoietic stem cell transplantation: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Although HLA matching is considered as a key genetic predictor of allo-HSCT outcomes, genetic polymorphisms in non-HLA genes, especially in genes encoding immunoregulatory proteins, have also been proposed as additional risk factors linked to the occurrence of transplant complications. This study aimed to carry out a systematic review and meta-analysis from all eligible cohort studies to determine the effect of CTLA-4 gene polymorphisms, including rs231775, rs3087243, rs4553808, rs5742909, and rs733618, on clinical outcomes in patients receiving an allo-HSCT.

METHODS

A systematic literature search in PubMed, Web of Science, and Scopus was performed to identify the relevant studies, and related information was extracted. The effect size (ES) and corresponding 95% confidence intervals (CIs) were calculated to estimate the association.

RESULTS

16 studies were eligible and included in the meta-analysis. The pooled results showed that only the dominant models of rs3087243 were significantly associated with chronic GVHD (cGVHD), while other SNPs were not significantly associated with overall survival, disease-free survival, relapse, and GVHD.

CONCLUSIONS

Our study represents, for the first time, a comprehensive meta-analysis on the role of CTLA-4 polymorphisms on outcomes after allo-HSCT. The results indicate that the CT60 CTLA-4 polymorphism could be a significant risk factor for cGVHD.

Association of recipient and donor interleukin 6 polymorphisms 174 and 597 with outcome after allogeneic hematopoietic stem cell transplantation in children

Purpose

The success of allogeneic hematopoietic stem cell transplantation (HSCT) is compromised by complications such as infection, relapse, and graft-versus-host disease (GVHD). The investigation of non-HLA immunogenetics, particularly of cytokines, could identify predictors of an unfavorable outcome after allogeneic HSCT. In this study, we examined the impact of single nucleotide polymorphisms (SNPs) within the promoter region of interleukin 6 (IL6) on the development of GVHD after pediatric allogeneic HSCT.

Methods

In this retrospective analysis, we included 320 pediatric patients with a median age of 10 years who underwent an allogeneic HSCT and their respective donors. We used TaqMan real-time polymerase chain reaction to analyze the SNPs IL6-174 (G/C) and IL6-597 (G/A). The IL6-174 polymorphism was examined in 300 recipients and 295 donors. The IL6-597 polymorphism was analyzed in 299 recipients and 296 donors. We investigated the influence of the IL6-174 and IL6-597 polymorphisms on overall survival, event-free survival, relapse incidence, transplant-related mortality, and the occurrence of GVHD.

Results

G polymorphism at position 174 of the recipient IL6 gene was associated with a higher incidence of acute GVHD (GG vs. GC/CC; P = 0.024). Patients with IL6-597 GG genotype developed acute GVHD more frequently than individuals with an A allele (GG vs. GA vs. AA; P = 0.013). IL6-174 GG homozygous recipients had a more frequent occurrence of chronic GVHD (GG vs. GC/CC; P = 0.049). We observed a significant increased risk of chronic GVHD in recipients with IL6-597 GG genotype (GG vs. GA vs. AA; P = 0.043). Polymorphisms of donors did not affect the incidence of acute GVHD and chronic GVHD. In multivariate analysis, the IL6-174 and IL6-597 SNPs were independent significant risk factors for acute GVHD (P = 0.030; P = 0.007, respectively) as well as for chronic GVHD (P = 0.045; P = 0.015, respectively). In addition, older age at time of transplantation turned out to be a significant risk factor for chronic GVHD (P = 0.003).

Conclusion

Our study identified the IL6-174 and IL6-597 GG genotypes of pediatric allogeneic HSCT recipients as genetic risk factors for the development of acute GVHD and chronic GVHD. After evaluations in further studies, these findings could implicate the adjustment of prophylactic measures to reduce the occurrence of acute GVHD and chronic GVHD.

Analysis of Relationships between Immune Checkpoint and Methylase Gene Polymorphisms and Outcomes after Unrelated Bone Marrow Transplantation

Simple Summary

Hematopoietic stem-cell transplantation (HSCT) is a curative therapy for blood disorders. Unrelated bone marrow transplantation (uBMT) is a type of allogeneic HSCT that uses the bone marrow of an unrelated donor. While HLA mismatch is a risk factor for poor outcomes in HSCT, such as graft-versus-host disease (GVHD), the importance of non-HLA single-nucleotide polymorphisms (SNPs) remains unclear. The clinical application of immune checkpoint and chromatin methylation inhibitors to cancer has been attracting attention. In the present study, we retrospectively genotyped five SNPs in four immune checkpoint genes, BTLA, PD-1, LAG3, and CTLA4, and two SNPs in methylase genes, DNMT1 and EZH2, in 999 uBMT pairs. Although no correlations were observed between these SNPs and post-uBMT outcomes, recipient EZH2 SNP exhibited a low p-value in the analysis of grade 2–4 acute GVHD (p = 0.010). This SNP may be useful for outcome predictions and needs to be confirmed in a larger-scale study.

Abstract

Unrelated bone marrow transplantation (uBMT) is performed to treat blood disorders, and it uses bone marrow from an unrelated donor as the transplant source. Although the importance of HLA matching in uBMT has been established, that of other genetic factors, such as single-nucleotide polymorphisms (SNPs), remains unclear. The application of immunoinhibitory receptors as anticancer drugs has recently been attracting attention. This prompted us to examine the importance of immunoinhibitory receptor SNPs in uBMT. We retrospectively genotyped five single-nucleotide polymorphisms (SNPs) in the immune checkpoint genes, BTLA, PD-1, LAG3, and CTLA4, and two SNPs in the methylase genes, DNMT1 and EZH2, in 999 uBMT donor–recipient pairs coordinated through the Japan Marrow Donor Program matched at least at HLA-A, -B, and -DRB1. No correlations were observed between these SNPs and post-uBMT outcomes (p > 0.005). This result questions the usefulness of these immune checkpoint gene polymorphisms for predicting post-BMT outcomes. However, the recipient EZH2 histone methyltransferase gene SNP, which encodes the D185H substitution, exhibited a low p-value in regression analysis of grade 2–4 acute graft-versus-host disease (p = 0.010). Due to a low minor allele frequency, this SNP warrants further investigation in a larger-scale study.

Recipient and donor genetic variants associated with mortality after allogeneic hematopoietic cell transplantation

Many studies have suggested that genetic variants in donors and recipients are associated with survival-related outcomes after allogeneic hematopoietic cell transplantation (HCT), but these results have not been confirmed. Therefore, the utility of testing genetic variants in donors and recipients for risk stratification or understanding mechanisms leading to mortality after HCT has not been established. We tested 122 recipient and donor candidate variants for association with nonrelapse mortality (NRM) and relapse mortality (RM) in a cohort of 2560 HCT recipients of European ancestry with related or unrelated donors. Associations discovered in this cohort were tested for replication in a separate cohort of 1710 HCT recipients. We found that the donor rs1051792 A allele in MICA was associated with a lower risk of NRM. Donor and recipient rs1051792 genotypes were highly correlated, making it statistically impossible to determine whether the donor or recipient genotype accounted for the association. Risks of grade 3 to 4 graft-versus-host disease (GVHD) and NRM in patients with grades 3 to 4 GVHD were lower with donor MICA-129Met but not with MICA-129Val, implicating MICA-129Met in the donor as an explanation for the decreased risk of NRM after HCT. Our analysis of candidate variants did not show any other association with NRM or RM. A genome-wide association study did not identify any other variants associated with NRM or RM.

Cytokine gene polymorphisms are associated with response to blinatumomab in B-cell acute lymphoblastic leukemia

Blinatumomab is a bispecific T cell-engaging antibody approved for treatment of relapsed/refractory (r/r) ALL, with 40%-50% complete response (CR)/CR with incomplete count recovery (CRi). Cytokine release syndrome (CRS) as a major adverse effect after blinatumomab therapy. Here, we evaluated the possible association between single-nucleotide polymorphisms (SNPs) in cytokine genes, disease response, and CRS in r/r ALL patients who received blinatumomab between 2012 and 2017 at our center (n = 66), using patients' archived DNA samples. With a median duration of 9.5 months (range: 1-37), 37 patients (56.1%) achieved CR/CRi, 54 (81.8%) experienced CRS (G1: n = 35, G2: n = 14, G3: n = 5), and 9 (13.6%) developed neurotoxicity. By multivariable analysis, after adjusting for high disease burden, one SNP on IL2 (rs2069762), odds ratio (OR) = 0.074 (95% CI: NE-0.43, P = .01) and one SNP on IL17A (rs4711998), OR = 0.28 (95% CI: 0.078-0.92, P = .034) were independently associated with CR/CRi. None of the analyzed SNPs were associated with CRS. To our knowledge, this is the first study demonstrating a possible association between treatment response to blinatumomab and SNPs. Our hypothesis-generated data suggest a potential role for IL-17 and IL-2 in blinatumomab response and justify a larger confirmatory study, which may lead to personalized blinatumomab immunotherapy for B-ALL.

Toll-like Receptor 4 Gene Polymorphisms in Chinese Population After Allogeneic Hematopoietic Stem Cell Transplantation

Objectives::

Graft-versus-host disease (GVHD) is the most common complication after hematopoietic stem cell transplantation (HSCT) and remains to be a major cause of mortality. Activation of toll-like receptor 4 (TLR-4) by lipopolysaccharide induces the NF-κB signaling pathway to release critical proinflammatory cytokines and increases the recipient response to GVHD. In order to clarify the role of TLR-4 in the occurrence of acute GVHD after HSCT, we collected 208 samples from HSCT recipients and their human lecucyte antigen identical donors to test the hypothesis that TLR-4polymorphism in the recipients or donors influence the risk of acute GVHD in allogeneic HSCT recipients.

Methods::

TLR-4 Asp299Gly and Thr399Ile polymorphisms of each sample were examined by using DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism methods.

Results::

No homozygous or heterozygous variant alleles of the Asp299Gly or Thr339Ile polymorphism were detected in any samples in our study. Our results demonstrate that TLR-4 Asp299Gly and Thr399Ile polymorphisms might be very rare in the Chinese population (Eastern China and Taiwan region).

Conclusion::

The results of this study cannot confirm the role of TLR-4 mutations in the pathogenesis of GVHD in humans, yet we reach a definite conclusion by a TLR-4 knockout murine GVHD model in our ongoing project.

Meta-Analysis of Genome-Wide Association and Gene Expression Studies Implicates Donor T Cell Function and Cytokine Pathways in Acute GvHD

Graft-vs.-host disease (GvHD) is a major complication after allogeneic hematopoietic stem cell transplantation that causes mortality and severe morbidity. Genetic disparities in human leukocyte antigens between the recipient and donor are known contributors to the risk of the disease. However, the overall impact of genetic component is complex, and consistent findings across different populations and studies remain sparse. To gain a comprehensive understanding of the genes responsible for GvHD, we combined genome-wide association studies (GWAS) from two distinct populations with previously published gene expression studies on GvHD in a single gene-level meta-analysis. We hypothesized that genes driving GvHD should be associated in both data modalities and therefore could be detected more readily through their combined effects in the integrated analysis rather than in separate analyses. The meta-analysis yielded a total of 51 acute GvHD-associated genes (false detection rate [FDR] <0.1). In support of our hypothesis, this number was significantly higher than that in a permutation meta-analysis involving the whole data set, as well as in separate meta-analyses on the GWAS and gene expression data sets. The genes indicated by the meta-analysis were significantly enriched in 277 Gene Ontology terms (FDR < 0.05), such as T cell function and cytokine-mediated signaling pathways, and the results highlighted several established immune mediators, such as interleukins and JAK-STAT signaling, and presented TRAF6 and TERT as potential effector candidates. Altogether, the results support the chosen methodological approach, implicate a role of gene-level variation in donors' key immunological regulators predisposing patients to acute GVHD, and present potential targets for therapeutic intervention.

NFKB1 gene single-nucleotide polymorphisms: implications for graft-versus-host disease in allogeneic hematopoietic stem cell transplantation

Graft-versus-host disease (GVHD) represents a significant cause of mortality after allogeneic hematopoietic stem cell transplantation (HSCT). NF-kB system is a master regulator of innate immunity responses. It controls the expression of various cytokines and chemokines many of which are involved in GVHD pathogenesis. Chemo(radio) therapy administered during conditioning induces DNA damage and activates DNA damage response (DDR) signaling resulting in irreversible cell cycle arrest - cellular senescence which has been described to be associated with robust pro-inflammatory secretion mostly controlled by NF-kB. The NFKB1 gene encodes the DNA-binding subunit of the NF-kB complex. Using the candidate gene approach, we analyzed possible association of two single-nucleotide polymorphisms (SNPs) rs3774937 C/T and rs3774959 A/G of the NFKB1 gene with GVHD and transplant-related mortality (TRM) occurrence in 109 recipients allografted from HLA-identical donor. Both SNPs in recipients were found to be strongly associated with acute GVHD. Nevertheless, no significant association with chronic GVHD and TRM was found. Presented pilot results contribute to pre-clinical observations and suggest that NF-kB may be an important regulator of HSCT-related inflammatory reactions such as acute GVHD. Novel pathogenic mechanisms of GVHD may arise from perspectives of DDR and cellular senescence where NF-kB plays an essential role.

The effects of gene polymorphisms on susceptibility to acute GVHD and survival of allogeneic HSCT recipients: IL-10 gene polymorphisms as a more accessible target to predict prognosis

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a therapeutic modality commonly used to treat hematological and immunological disorders. Among the main complications of allo-HSCT is the acute graft-versus-host disease (a-GVHD), a condition which accounts for a high incidence of mortality. Several genes encoding inflammatory mediators may present polymorphisms, which have been implicated in the risk of developing a-GVHD. In our study, we investigated the association between genotypes of cytokine-encoding genes and the incidence and severity of a-GVHD and survival of HSCT recipients. No statistically significant association was found between IL and 6-174 G/C, INF-γ + 874 T/A, TNF-α -238 A/G, -308 A/G and IL-10-819C/T, -592 A/C polymorphisms and the presence or severity of a-GVHD. A higher risk of a-GVHD was associated with the IL-10-1082 GG genotype compared to the AA + AG genotypes of recipients and donors. The IL-10-1082 genotype can be used as a prognostic determinant to predict which HSCT recipient will be more responsive to the transplant. Thus, cytokine gene assays may be useful in the individualization of prophylactic regimens and for an appropriate selection of immunosuppressants based on the HSCT recipient's responsiveness.

Seeking biomarkers for acute graft-versus-host disease: where we are and where we are heading?

Acute graft-versus-host disease (aGVHD) is one of the most important complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT), which would seriously affect the clinical outcomes of patients. Early diagnosis and early intervention are keys for improving its curative efficacy. Thus, seeking the biomarkers of aGVHD that can accurately identify and diagnose aGVHD is very important to guiding the intervention and treatment of aGVHD. For the past decades, many studies have focused on searching for aGVHD-related biological markers to assist in diagnosis, early warning, and risk stratification. Unfortunately, until now, no reliable aGVHD biomarker is available that is recognized and widely used in clinical practice. With the continuous development of biological technology, as well as our in-depth understanding of the pathophysiologic mechanism of aGVHD, the selection, examination and application of biological markers have changed much. In this review, we summarized the progress of aGVHD biological marker screening, identification, preliminary clinical application, and look forward to a promising development direction in the future.

Altered donor P2X7 activity in human leukocytes correlates with P2RX7 genotype but does not affect the development of graft-versus-host disease in humanised mice

Graft-versus-host disease (GVHD) is a life-threatening consequence of allogeneic haematopoietic stem cell transplantation, a curative therapy for haematological malignancies. The ATP-gated P2X7 receptor channel is implicated in the development of GVHD. P2X7 activity on human leukocytes can be influenced by gain-of-function (GOF) and loss-of-function (LOF) single nucleotide polymorphisms (SNPs) in the P2RX7 gene. In this study, the P2RX7 gene was sequenced in 25 human donors and the P2X7 activity on subsets of peripheral blood T cells, natural killer (NK) cells and monocytes was measured using an ATP-induced dye uptake assay. GOF and LOF SNPs representing 10 of the 17 known P2RX7 haplotypes were identified, and correlated with P2X7 activity on all leukocyte subsets investigated. Notably, invariant (i) NK T cells displayed the highest P2X7 activity amongst all cell types studied. To determine if donor P2X7 activity influenced the development of GVHD, immunodeficient NOD-SCID-IL2Rγnull (NSG) mice were injected with human peripheral blood mononuclear cells isolated from donors of either GOF (hP2X7GOF mice) or LOF (hP2X7LOF mice) P2RX7 genotype. Both hP2X7GOF and hP2X7LOF mice demonstrated similar human leukocyte engraftment, and showed comparable weight loss, GVHD clinical score and overall survival. Donor P2X7 activity did not affect human leukocyte infiltration or GVHD-mediated tissue damage, or the relative expression of human P2X7 or human interferon-γ (hIFNγ) in tissues. Finally, hP2X7GOF and hP2X7LOF mice demonstrated similar concentrations of serum hIFNγ. This study demonstrates that P2X7 activity correlates with donor P2RX7 genotype on human leukocyte subsets important in GVHD development, but does not affect GVHD development in a humanised mouse model of this disease.

Genomic prediction of relapse in recipients of allogeneic haematopoietic stem cell transplantation

Allogeneic haematopoietic stem cell transplantation currently represents the primary potentially curative treatment for cancers of the blood and bone marrow. While relapse occurs in approximately 30% of patients, few risk-modifying genetic variants have been identified. The present study evaluates the predictive potential of patient genetics on relapse risk in a genome-wide manner. We studied 151 graft recipients with HLA-matched sibling donors by sequencing the whole-exome, active immunoregulatory regions, and the full MHC region. To assess the predictive capability and contributions of SNPs and INDELs, we employed machine learning and a feature selection approach in a cross-validation framework to discover the most informative variants while controlling against overfitting. Our results show that germline genetic polymorphisms in patients entail a significant contribution to relapse risk, as judged by the predictive performance of the model (AUC = 0.72 [95% CI: 0.63-0.81]). Furthermore, the top contributing variants were predictive in two independent replication cohorts (n = 258 and n = 125) from the same population. The results can help elucidate relapse mechanisms and suggest novel therapeutic targets. A computational genomic model could provide a step toward individualized prognostic risk assessment, particularly when accompanied by other data modalities.

A novel predictive approach for GVHD after allogeneic SCT based on clinical variables and cytokine gene polymorphisms

Despite considerable advances in our understanding of the pathophysiology of graft-versus-host disease (GVHD), its prediction remains unresolved and depends mainly on clinical data. The aim of this study is to build a predictive model based on clinical variables and cytokine gene polymorphism for predicting acute GVHD (aGVHD) and chronic GVHD (cGVHD) from the analysis of a large cohort of HLA-identical sibling donor allogeneic stem cell transplant (allo-SCT) patients. A total of 25 SNPs in 12 cytokine genes were evaluated in 509 patients. Data were analyzed using a linear regression model and the least absolute shrinkage and selection operator (LASSO). The statistical model was constructed by randomly selecting 85% of cases (training set), and the predictive ability was confirmed based on the remaining 15% of cases (test set). Models including clinical and genetic variables (CG-M) predicted severe aGVHD significantly better than models including only clinical variables (C-M) or only genetic variables (G-M). For grades 3-4 aGVHD, the correct classification rates (CCR1) were: 100% for CG-M, 88% for G-M, and 50% for C-M. On the other hand, CG-M and G-M predicted extensive cGVHD better than C-M (CCR1: 80% vs. 66.7%, respectively). A risk score was calculated based on LASSO multivariate analyses. It was able to correctly stratify patients who developed grades 3-4 aGVHD (P < .001) and extensive cGVHD (P < .001). The novel predictive models proposed here improve the prediction of severe GVHD after allo-SCT. This approach could facilitate personalized risk-adapted clinical management of patients undergoing allo-SCT.

Patient HLA Germline Variation and Transplant Survivorship

Purpose HLA mismatching increases mortality after unrelated donor hematopoietic cell transplantation. The role of the patient's germline variation on survival is not known. Patients and Methods We previously identified 12 single nucleotide polymorphisms within the HLA region as markers of transplantation determinants and tested these in an independent cohort of 1,555 HLA-mismatched unrelated transplants. Linkage disequilibrium mapping across class II identified candidate susceptibility features. The candidate gene was confirmed in an independent cohort of 3,061 patients. Results Patient rs429916AA/AC was associated with increased transplantation-related mortality compared with rs429916CC (hazard ratio [HR], 1.39; 95% CI, 1.12 to 1.73; P = .003); rs429916A positivity was a proxy for DOA*01:01:05. Mortality increased with one (HR, 1.17; 95% CI, 1.0 to 1.36; P = .05) and two (HR, 2.51; 95% CI, 1.41 to 4.45; P = .002) DOA*01:01:05 alleles. HLA-DOA*01:01:05 was a proxy for HLA-DRB1 alleles encoding FEY ( P < 10E^-15) and FDH ( P < 10E^-15) amino acid substitutions at residues 26/28/30 that influence HLA-DRβ peptide repertoire. FEY- and FDH-positive alleles were positively associated with rs429916A ( P < 10E^-15); FDY-positive alleles were negatively associated. Mortality was increased with FEY (HR, 1.66; 95% CI, 1.29 to 2.13; P = .00008) and FDH (HR, 1.40; 95% CI, 1.02 to 1.93; P = .04), whereas FDY was protective (HR, 0.88; 95% CI, 0.78 to 0.98; P = .02). Of the three candidate motifs, FEY was validated as the susceptibility determinant for mortality (HR, 1.29; 95% CI, 1.00 to 1.67; P = .05). Although FEY was found frequently among African and Hispanic Americans, it increased mortality independently of ancestry. Conclusion Patient germline HLA-DRB1 alleles that encode amino acid substitutions that influence the peptide repertoire of HLA-DRβ predispose to increased death after transplantation. Patient germline variation informs transplantation outcomes across US populations and may provide a means to reduce risks for high-risk patients through pretransplantation screening and evaluation.

A pilot study of single nucleotide polymorphisms in the interleukin-6 receptor and their effects on pre- and post-transplant serum mediator level and outcome after allogeneic stem cell transplantation

Interleukin (IL)-6 is an important regulator of immunity and inflammation in many diseases. Single nucleotide polymorphisms (SNPs) in the IL-6 gene influence outcome after allogeneic stem cell transplantation (ASCT), but the possible importance of SNPs in the IL-6 receptor has not been examined. We therefore investigated whether SNPs in the IL-6R gene influenced biochemical characteristics and clinical outcomes after ASCT. We examined the IL-6 promoter variant rs1800975 and the IL-6R SNPs rs4453032, rs2228145, rs4129267, rs4845374, rs4329505, rs4845617, rs12083537, rs4845618, rs6698040 and rs4379670 in a 101 population-based cohort of allotransplant recipients and their family donors. Patients being homozygous for the major alleles of the IL-6R SNPs rs2228145 and rs4845618 showed high pretransplant CRP serum levels together with decreased sIL-6R levels; the decreased IL-6R levels persisted 6 months post-transplant. In contrast, patients being homozygous for the minor allele of the IL-6R SNP rs4379670 showed decreased pretransplant CRP levels. Furthermore, the IL-6R rs4845618 donor genotype showed an association with severe acute graft-versus-host disease (GVHD), whereas the donor genotype of the IL-6 SNP rs1800795 was associated with decreased survival 100 days post-transplant. Finally, the recipient genotype of the IL-6R SNP rs4329505 showed a strong association with 2-years non-relapse mortality, and this effect was also highly significant in multivariate analysis. IL-6 and IL-6R SNPs influence the clinical outcome after allogeneic stem cell transplantation.

Graft versus Host Disease: From Basic Pathogenic Principles to DNA Damage Response and Cellular Senescence

Graft versus host disease (GVHD), a severe immunogenic complication of allogeneic hematopoietic stem cell transplantation (HSCT), represents the most frequent cause of transplant-related mortality (TRM). Despite a huge progress in HSCT techniques and posttransplant care, GVHD remains a significant obstacle in successful HSCT outcome. This review presents a complex summary of GVHD pathogenesis with focus on references considering basic biological processes such as DNA damage response and cellular senescence.

The Influence of Genetic Variations in the CD86 Gene on the Outcome after Allogeneic Hematopoietic Stem Cell Transplantation

CD86 molecule is the ligand for both costimulatory (CD28) and coinhibitory (CTLA-4) molecules, and it regulates immune response after allogeneic hematopoietic stem cell transplantation (alloHSCT). Therefore, we postulate that CD86 gene variations might influence the outcome after alloHSCT. Altogether, 295 adult patients (pts) undergoing related (105 pts) and unrelated (190 pts) donor-matched HSCT were genotyped for the following CD86 gene polymorphisms: rs1129055, rs9831894, and rs2715267. Moreover, the donors' rs1129055 polymorphism was determined. None of the investigated SNPs alone were associated with aGvHD and rate of relapse. However, we showed that rs2715267 SNP influenced overall survival (OS) after alloHSCT. The 24-month OS for the rs271526GG recipients was worse than that for the recipients possessing T allelle (TT or GT genotypes) (p = 0.009). Moreover, analysis of gene-gene interaction between CD86 and CTLA-4 showed that having both the A allele for CD86 rs1129055 and the CTLA-4 CT60GG genotype in recipients increased the risk of aGvHD about 3.5 times. Interestingly, the donors' rs1129055GG genotype and the recipients' CT60GG genotype also increased the risk of aGvHD about 2.7-fold. We postulate that recipients' CD86 gene polymorphisms influence the overall survival after alloHSCT and, together with CTLA-4 polymorphisms, might be considered a risk factor for aGvHD.

Tocilizumab, tacrolimus and methotrexate for the prevention of acute graft-versus-host disease: low incidence of lower gastrointestinal tract disease

We conducted a phase 2 study in which patients undergoing allogeneic hematopoietic stem cell transplantation received tocilizumab in addition to standard immune suppression with tacrolimus and methotrexate for graft-versus-host disease prophylaxis. Thirty-five patients were enrolled between January 2015 and June 2016. The median age of the cohort was 66 (range: 22-76). All patients received busulfan-based conditioning, and were transplanted with human leukocyte antigen-matched related or matched unrelated bone marrow or peripheral stem cell grafts. The cumulative incidences of grades II-IV and III-IV acute graft-versus-host disease were 14% (95% CI 5-30) and 3% (95% CI 0-11) at day 100, and 17% (95% CI 7-31) and 6% (95% CI 1-16) at day 180, respectively. Notably, there were no cases of graft-versus-host disease of the lower gastrointestinal tract within the first 100 days. A comparison to 130 matched controls who only received tacrolimus and methotrexate demonstrated a lower cumulative incidence of grades II-IV acute graft-versus-host disease (17% versus 45%, P=0.003) and a significant increase in grades II-IV acute graft-versus-host disease-free survival at six months (69% versus 42%, P=0.001) with tocilizumab, tacrolimus and methotrexate, which was the primary endpoint of the study. Immune reconstitution was preserved in patients treated with tocilizumab, tacrolimus and methotrexate, as T-cell and B-cell subsets recovered to near normal levels by 6-12 months post-transplantation. We conclude that tocilizumab has promising activity in preventing acute graft-versus-host disease, particularly in the lower gastrointestinal tract, and warrants examination in a randomized setting.

Genetic polymorphism related to monocyte-macrophage function is associated with graft-versus-host disease

Despite detailed human leukocyte antigen (HLA) matching and modern immunosuppressive therapy, severe graft-versus-host disease (GvHD) remains a major hurdle for successful allogeneic hematopoietic stem cell transplantation (HSCT). As the genetic diversity in GvHD complicates the systematic discovery of associated variants across populations, we studied 122 GvHD-associated single nucleotide polymorphisms (SNPs) in 492 HLA-matched sibling HSCT donor-recipient pairs from Finland and Spain. The association between these candidate SNPs and grade III–IV acute GvHD and extensive chronic GvHD was assessed. The functional effects of the variants were determined using expression and cytokine quantitative trait loci (QTL) database analyses. Clear heterogeneity was observed in the associated markers between the two populations. Interestingly, the majority of markers, such as those annotated to IL1, IL23R, TLR9, TNF, and NOD2 genes, are related to the immunological response by monocytes-macrophages to microbes, a step that precedes GvHD as a result of intestinal lesions. Furthermore, cytokine QTL analysis showed that the GvHD-associated markers regulate IL1β, IFNγ, and IL6 responses. These results support a crucial role for the anti-microbial response in GvHD risk. Furthermore, despite apparent heterogeneity in the genetic markers associated with GvHD, it was possible to identify a biological pathway shared by most markers in both populations.

Associations of interactions between NLRP3 SNPs and HLA mismatch with acute and extensive chronic graft-versus-host diseases

HLA matching is a well-known genetic requirement for successful bone marrow transplantation (BMT). However, the importance of non-HLA single-nucleotide polymorphisms (SNPs) remains poorly understood. The NLR family pyrin domain-containing 3 (NLRP3) inflammasome, a key regulator of innate immunity, is associated with multiple diseases. We retrospectively genotyped SNPs of NLRP1-3 and caspase recruitment domain family member 8 (CARD8), which are implicated in the interleukin 1β (IL-1β) signaling, in 999 unrelated BMT donor-recipient pairs. We identified an association of the interaction between the recipient NLRP3 SNP CC genotype and total HLA mismatches with grade 2-4 acute graft-versus-host disease (AGVHD), and an association of the interaction between the donor NLRP3 SNP T allele and HLA-C mismatch with extensive chronic GVHD (ECGVHD), in both adjusted and unadjusted regressions (P < 0.005). Importantly, the ECGVHD risk associated with HLA-C mismatch was not elevated when the donor NLRP3 genotype was CC. We also identified an association of the interaction between recipient NLRP3 SNP and donor cytomegalovirus seropositivity with overall survival in adjusted regressions (P < 0.005). These results suggest the importance of certain SNP-covariate interactions in unrelated BMT. The three identified interactions may be useful for donor selection or outcome prediction.

Replication and validation of genetic polymorphisms associated with survival after allogeneic blood or marrow transplant

Multiple candidate gene-association studies of non-HLA single-nucleotide polymorphisms (SNPs) and outcomes after blood or marrow transplant (BMT) have been conducted. We identified 70 publications reporting 45 SNPs in 36 genes significantly associated with disease-related mortality, progression-free survival, transplant-related mortality, and/or overall survival after BMT. Replication and validation of these SNP associations were performed using DISCOVeRY-BMT (Determining the Influence of Susceptibility COnveying Variants Related to one-Year mortality after BMT), a well-powered genome-wide association study consisting of 2 cohorts, totaling 2888 BMT recipients with acute myeloid leukemia, acute lymphoblastic leukemia, or myelodysplastic syndrome, and their HLA-matched unrelated donors, reported to the Center for International Blood and Marrow Transplant Research. Gene-based tests were used to assess the aggregate effect of SNPs on outcome. None of the previously reported significant SNPs replicated at P < .05 in DISCOVeRY-BMT. Validation analyses showed association with one previously reported donor SNP at P < .05 and survival; more associations would be anticipated by chance alone. No gene-based tests were significant at P < .05. Functional annotation with publicly available data shows these candidate SNPs most likely do not have biochemical function; only 13% of candidate SNPs correlate with gene expression or are predicted to impact transcription factor binding. Of these, half do not impact the candidate gene of interest; the other half correlate with expression of multiple genes. These findings emphasize the peril of pursing candidate approaches and the importance of adequately powered tests of unbiased genome-wide associations with BMT clinical outcomes given the ultimate goal of improving patient outcomes.

Association between single nucleotide polymorphisms of tumor necrosis factor gene and grade II-IV acute GvHD: a systematic review and meta-analysis

Acute GvHD (aGvHD) complicates up to 50% of allogeneic hematopoietic cell transplants and pre-transplant estimation of its risk can guide prophylaxis, monitoring and early intervention strategies. Inspired by the role of tumor necrosis factor alpha (TNFα) in the pathogenesis of aGvHD and the inconsistency of the association studies exploring single nucleotide polymorphisms (SNPs) of the TNF gene, we conducted a systematic review and meta-analysis of the available reports using PubMed and EMBASE. Original human studies reporting on the association between recipient TNF SNPs and grade II-IV aGvHD in a format convertible to effect size and confidence interval were included. One of the two most widely investigated SNPs (rs361525G>A) was marginally associated with increased risk of grade II-IV aGvHD in random-effects meta-analysis of six studies (627 patients in total, risk ratio=1.29, 95% confidence interval=0.99-1.69, P=0.06). If this result is validated in a large cohort with uniform conditioning and GvHD prophylaxis, TNF rs361525G>A may become a useful tool for aGvHD risk estimation before the transplant.

Interleukin-6 in Allogeneic Stem Cell Transplantation: Its Possible Importance for Immunoregulation and As a Therapeutic Target

Allogeneic stem cell transplantation is associated with a high risk of treatment-related mortality mainly caused by infections and graft-versus-host disease (GVHD). GVHD is characterized by severe immune dysregulation and impaired regeneration of different tissues, i.e., epithelial barriers and the liver. The balance between pro- and anti-inflammatory cytokine influences the risk of GVHD. Interleukin-6 (IL-6) is a cytokine that previously has been associated with pro-inflammatory effects. However, more recent evidence from various autoimmune diseases (e.g., inflammatory bowel disease, rheumatoid arthritis) has shown that the IL-6 activity is more complex with important effects also on tissue homeostasis, regeneration, and metabolism. This review summarizes the current understanding of how pro-inflammatory IL-6 effects exerted during the peritransplant period shapes T-cell polarization with enhancement of Th17 differentiation and suppression of regulatory T cells, and in addition we also review and discuss the results from trials exploring non-selective IL-6 inhibition in prophylaxis and treatment of GVHD. Emerging evidence suggests that the molecular strategy for targeting of IL-6-initiated intracellular signaling is important for the effect on GVHD. It will therefore be important to further characterize the role of IL-6 in the pathogenesis of GVHD to clarify whether combined IL-6 inhibition of both trans- (i.e., binding of the soluble IL-6/IL-6 receptor complex to cell surface gp130) and cis-signaling (i.e., IL-6 ligation of the IL-6 receptor/gp130 complex) or selective inhibition of trans-signaling should be tried in the prophylaxis and/or treatment of GVHD in allotransplant patients.

Role of major histocompatibility complex variation in graft-versus-host disease after hematopoietic cell transplantation

Graft-versus-host disease (GVHD) remains a significant potentially life-threatening complication of allogeneic hematopoietic cell transplantation (HCT). Since the discovery of the human leukocyte antigen (HLA) system over 50 years ago, significant advances have clarified the nature of HLA variation between transplant recipients and donors as a chief etiology of GVHD. New information on coding and non-coding gene variation and GVHD risk provides clinicians with options to consider selected mismatched donors when matched donors are not available. These advances have increased the availability of unrelated donors for patients in need of a transplant and have lowered the overall morbidity and mortality of HCT.

Genetic Association of Hematopoietic Stem Cell Transplantation Outcome beyond Histocompatibility Genes

The outcome of hematopoietic stem cell transplantation (HSCT) is controlled by genetic factors among which the leukocyte antigen human leukocyte antigen (HLA) matching is most important. In addition, minor histocompatibility antigens and non-HLA gene polymorphisms in genes controlling immune responses are known to contribute to the risks associated with HSCT. Besides single-nucleotide polymorphisms (SNPs) in protein coding genes, SNPs in regulatory elements such as microRNAs (miRNAs) contribute to these genetic risks. However, genetic risks require for their realization the expression of the respective gene or miRNA. Thus, gene and miRNA expression studies may help to identify genes and SNPs that indeed affect the outcome of HSCT. In this review, we summarize gene expression profiling studies that were performed in recent years in both patients and animal models to identify genes regulated during HSCT. We discuss SNP–mRNA–miRNA regulatory networks and their contribution to the risks associated with HSCT in specific examples, including forkheadbox protein 3 and regulatory T cells, the role of the miR-155 and miR-146a regulatory network for graft-versus-host disease, and the function of MICA and its receptor NKG2D for the outcome of HSCT. These examples demonstrate how SNPs affect expression or function of proteins that modulate the alloimmune response and influence the outcome of HSCT. Specific miRNAs targeting these genes and directly affecting expression of mRNAs are identified. It might be valuable in the future to determine SNPs and to analyze miRNA and mRNA expression in parallel in cohorts of HSCT patients to further elucidate genetic risks of HSCT.

Transplant genetics and genomics

Ever since the discovery of the major histocompatibility complex, scientific and clinical understanding in the field of transplantation has been advanced through genetic and genomic studies. Candidate-gene approaches and recent genome-wide association studies (GWAS) have enabled a deeper understanding of the complex interplay of the donor-recipient interactions that lead to transplant tolerance or rejection. Genetic analysis in transplantation, when linked to demographic and clinical outcomes, has the potential to drive personalized medicine by enabling individualized risk stratification and immunosuppression through the identification of variants associated with immune-mediated complications, post-transplant disease or alterations in drug-metabolizing genes.

Validation of single nucleotide polymorphisms in invasive aspergillosis following hematopoietic cell transplantation

Invasive aspergillosis (IA) is a significant cause of morbidity and mortality following allogeneic hematopoietic cell transplantation (HCT). Previous studies have reported an association between IA development and single nucleotide polymorphisms (SNPs), but many SNPs have not been replicated in a separate cohort. The presence of a positive serum galactomannan assay (SGM+) has also been associated with a worse prognosis in patients with IA, and genetic determinants in this subset of patients have not been systematically studied. The study cohort included 2609 HCT recipients and their donor pairs: 483 with proven/probable IA (183 SGM+) and 2126 with no IA by standard criteria. Of 25 SNPs previously published, we analyzed 20 in 14 genes that passed quality control. Samples were genotyped via microarray, and SNPs that could not be genotyped were imputed. The primary aim was to replicate SNPs associated with proven/probable IA at 2 years; secondary goals were to explore the associations using an end point of SGM+ IA or proven/probable IA using a different genetic model or time to IA (3 months vs 2 years) compared with the original study. Two SNPs in 2 genes (PTX3, CLEC7a) were replicated. Thirteen SNPs in 9 genes had an association at P ≤ .05 using the secondary aims (PTX3, CLEC7a, CD209, CXCL10, TLR6, S100B, IFNG, PLG, TNFR1), with hazard ratios ranging from 1.2 to 3.29. Underlying genetic differences can influence development of IA following HCT. Identification of genetic predispositions to IA could have important implications in donor screening, risk stratification of recipients, monitoring, and prophylaxis.

Transforming growth factor-β1 functional polymorphisms in myeloablative sibling hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) with sibling donors (s.d.) is a life-saving intervention for patients with hematological malignancies. Numerous genetic factors have a role in transplant outcome. Several functional polymorphisms have been identified in TGF-β1 gene, such as single-nucleotide polymorphism (SNP) at +29C>T within exon 1. Two hundred and forty five patient/donor pairs who underwent a s.d. HSCT in our centers were genotyped for this SNP. In the myeloablative cohort, +29CC donors were associated with an increase in severe chronic GvHD (32% vs 16%, hazard ratio (HR) 9.0, P=0.02). Regarding survival outcomes, +29CC patients developed higher non relapse mortality (NRM) (1-5 years CC 28-32% vs TC/TT 7-10%; HR 5.1, P=0.01). Recipients of +29TT donors experienced a higher relapse rate (1-5 years TT 37-51% vs TC 19-25% vs CC 13%-19%; HR 2.4, P=0.01) with a decreased overall survival (OS) (1-5 years TT 69-50% vs TC/CC 77-69%; HR 1.9, P=0.05). Similar to previous myeloablative unrelated donors HSCT results, we confirmed that +29CC patients had higher NRM. In addition we found that +29TT donors might be associated with a higher relapse rate and lower OS. These results should be confirmed in larger series. Identification of these SNPs will allow personalizing transplant conditioning and immunosuppressant regimens, as well as assisting in the choice of the most appropriate donor.

Replication of associations between genetic polymorphisms and chronic graft-versus-host disease

Previous studies have identified single-nucleotide polymorphisms (SNPs) associated with the risk of chronic graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation. The current study determined whether these associations could be replicated in large cohorts of donors and recipients. Each SNP was tested with cohorts of patients having the same donor type (HLA-matched related, unrelated, or both) reported in the original publication, and testing was limited to the same genome (recipient or donor) and genetic model (dominant, recessive, or allelic) reported in the original study. The 21 SNPs reported in this study represent 19 genes, and the analysis encompassed 22 SNP association tests. The hazard ratio (HR) point estimates and risk ratio point estimates corresponding to odds ratios in previous studies consistently fall outside the 95% confidence intervals of HR estimates in the current study. Despite the large size of the cohorts available for the current study, the 95% confidence intervals for most HRs did not exclude 1.0. Three SNPs representing CTLA4, HPSE, and IL1R1 showed evidence of association with the risk of chronic GVHD in unrelated donor-recipient pairs from 1 cohort, but none of these associations was replicated when tested in unrelated donor-recipient pairs from an independent cohort. Two SNPs representing CCR6 and FGFR1OP showed possible associations with the risk of chronic GVHD in related donor-recipient pairs but not in unrelated donor-recipient pairs. These results remain to be tested for replication in other cohorts of related donor-recipient pairs.

Recipient and donor JAK2 46/1 haplotypes are associated with acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation

Several genetic polymorphisms have been implicated to affect the outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT). The role of cytokines in acute graft-versus-host disease (aGvHD) is well established and many of the involved cytokines signal through the Janus kinase (JAK) pathways. In this study, we assessed the association of recipient and donor JAK2 46/1 haplotypes and allo-HSCT outcome in a cohort of 124 acute myeloid leukemia patients. Both, recipient and donor 46/1 haplotypes significantly affected aGvHD grades II-IV development (p = 0.006 and p = 0.031, respectively), furthermore the influence of the haplotypes seemed to be additive. In multivariate analyses the recipient haplotype remained independently related (p = 0.012) to aGvHD, while the donor not (p = 0.08). We observed significantly less relapses among haplotype carriers (p = 0.004), but overall survival did not differ (p = 0.732). Our findings suggest that recipient and donor JAK2 46/1 haplotypes might be involved in the regulation of aGvHD.

Genetic risk factors for sclerotic graft-versus-host disease

Sclerotic graft-versus-host disease (GVHD) is a distinctive phenotype of chronic GVHD after allogeneic hematopoietic cell transplantation, characterized by fibrosis of skin or fascia. Sclerotic GVHD has clinical and histopathological similarities with systemic sclerosis, an autoimmune disease whose risk is influenced by genetic polymorphisms. We examined 13 candidate single-nucleotide polymorphisms (SNPs) that have a well-documented association with systemic sclerosis to determine whether these SNPs are also associated with the risk of sclerotic GVHD. The study cohort included 847 consecutive patients who were diagnosed with chronic GVHD. Genotyping was performed using microarrays, followed by imputation of unobserved SNPs. The donor rs10516487 (BANK1: B-cell scaffold protein with ankyrin repeats 1) TT genotype was associated with lower risk of sclerotic GVHD (hazard ratio [HR], 0.43; 95% confidence interval [CI], 0.21-0.87; P = .02). Donor and recipient rs2056626 (CD247: T-cell receptor ζ subunit) GG or GT genotypes were associated with higher risk of sclerotic GVHD (HR, 1.57; 95% CI, 1.13-2.18; P = .007 and HR, 1.66; 95% CI, 1.19-2.32; P = .003, respectively). Donor and recipient rs987870 (5'-flanking region of HLA-DPA1) CC genotypes were associated with higher risk of sclerotic GVHD (HR, 2.50; 95% CI, 1.22-5.11; P = .01 and HR, 2.13; 95% CI, 1.00-4.54; P = .05, respectively). In further analyses, the recipient DPA1*01:03∼DPB1*04:01 haplotype and certain amino acid substitutions in the recipient P1 peptide-binding pocket of the HLA-DP heterodimer were associated with risk of sclerotic GVHD. Genetic components associated with systemic sclerosis are also associated with sclerotic GVHD. HLA-DP-mediated antigen presentation, T-cell response, and B-cell activation have important roles in the pathogenic mechanisms of both diseases.

Therapeutic targets and emerging treatment options in gastrointestinal acute graft-versus-host disease

Introduction

Graft-versus-host disease (GVHD) continues to be the major lethal complication of allogeneic hematopoietic stem cell transplantation (HCT) but the standard of care, high dose steroids, has not changed in 40 years. Approximately 50% of GVHD patients will develop steroid refractory disease, typically involving the gastrointestinal (GI) tract, which has a very poor prognosis. Newly developed GVHD biomarker-based risk scores provide the first opportunity to treat patients at the onset of symptoms according to risk of steroid failure. Furthermore, improvements in our understanding of the pathobiology of GVHD, its different signaling pathways, involved cytokines, and the role of post-translational and epigenetic modifications, has identified new therapeutic targets for clinical trials.

Areas covered

This manuscript summarizes the pathophysiology, diagnosis, staging, current and new targeted therapies for GVHD, with an emphasis on GI GVHD. A literature search on PubMed was undertaken and the most relevant references included.

Expert Opinion

The standard treatment for GVHD, high dose steroids, offers less than optimal outcomes as well as significant toxicities. Better treatments, especially for GI GVHD, are needed to reduce non-relapse mortality after allogeneic HCT. The identification of high risk patients through a biomarker-defined scoring system offers a personalized approach to a disease that still requires significant research attention.

Graft-versus-Host Disease after HLA-Matched Sibling Bone Marrow or Peripheral Blood Stem Cell Transplantation: Comparison of North American Caucasian and Japanese Populations

The risk of acute graft-versus-host disease (GVHD) after HLA-matched sibling bone marrow transplantation (BMT) is lower in Japanese than in Caucasian patients. However, race may have differential effect on GVHD dependent on the graft source. North American Caucasian and Japanese patients receiving their first allogeneic BMT or peripheral blood stem cell transplantation from an HLA-matched sibling for leukemia were eligible. BMT was performed in 13% of the Caucasian patients and in 53% of the Japanese patients. On multivariate analysis, the interaction term between race and graft source was not significant in any of the models, indicating that graft source does not affect the impact of race on outcomes. The risk of grade III or IV acute GVHD was significantly lower in the Japanese patients compared with the Caucasian patients (hazard ratio [HR], 0.74; 95% confidence interval [CI], 0.57 to 0.96), which resulted in lower risk of nonrelapse mortality in the Japanese patients (HR, 0.69; 95% CI, 0.54 to 0.89). The risk of relapse was also lower in this group. The lower risks of nonrelapse mortality and relapse resulted in lower overall mortality rates among the Japanese patients. In conclusion, our data indicate that irrespective of graft source, the risk of severe acute GVHD is lower in Japanese patients, resulting in a lower risk of nonrelapse mortality.

Clinical and Genetic Determinants of Cardiomyopathy Risk among Hematopoietic Cell Transplantation Survivors

Cardiomyopathy has been recognized as a complication after hematopoietic cell transplantation (HCT). Using a nested case-cohort design, we examined the relationships between demographic, therapeutic, and selected cardiovascular disease risk factors among ≥1-year HCT survivors who developed cardiomyopathy before (n = 43) or after (n = 89) 1 year from HCT as compared to a randomly selected subcohort of survivors without cardiomyopathy (n = 444). Genomic data were available for 79 cases and 267 noncases. Clinical and genetic covariates were examined for association with the risk of early or late cardiomyopathy. Clinical risk factors associated with both early- and late-onset cardiomyopathy included anthracycline exposure ≥250 mg/m(2) and pre-existing hypertension. Among late-onset cardiomyopathy cases, the development of diabetes and ischemic heart disease further increased risk. We replicated several previously reported genetic associations among early-onset cardiomyopathy cases, including rs1786814 in CELF4, rs2232228 in HAS3, and rs17863783 in UGT1A6. None of these markers were associated with risk of late-onset cardiomyopathy. A combination of demographic, treatment, and clinical covariates predicted early-onset cardiomyopathy with reasonable accuracy (area under the curve [AUC], .76; 95% confidence interval [CI], .68 to .83), but prediction of late cardiomyopathy was poor (AUC, .59; 95% CI .53 to .67). The addition of genetic polymorphisms with marginal associations (odds ratios ≥1.3) did not enhance prediction for either early- or late-onset cardiomyopathy. Conventional cardiovascular risk factors influence the risk of both early- and late-onset cardiomyopathy in HCT survivors. Although certain genetic markers may influence the risk of early-onset disease, further work is required to validate previously reported findings and to determine how genetic information should be incorporated into clinically useful risk prediction models.

Identification and utilization of donor and recipient genetic variants to predict survival after HCT: are we ready for primetime?

Overall survival following hematopoietic cell transplantation (HCT) has improved over the past two decades through better patient selection and advances in HLA typing, supportive care, and infection prophylaxis. Nonetheless, mortality rates are still unsatisfactory and transplant-related mortality remains a major cause of death after unrelated allogeneic HCT. Since there are no known pre-HCT, non-HLA biologic predictors of survival following transplant, for over a decade, scientists have been investigating the role of non-HLA germline genetic variation in survival and treatment-related mortality after HCT. Variation in single nucleotide polymorphisms (SNPs) has the potential to impact chemotherapy, radiation, and immune responses, leading to different post-HCT survival outcomes. In this paper, we address the current knowledge of the contribution of genetic variation to survival following HCT and discuss study design and methodology for investigating HCT survival on a genomic scale.