Immunoregulatory gene polymorphisms and graft-versus-host disease

Exploring the Bio-Functional Effect of Single Nucleotide Polymorphisms in the Promoter Region of the TNFSF4, CD28, and PDCD1 Genes

In a prior study, we discovered that hematopoietic stem cell transplantation (HSCT) and/or autoimmune diseases, such as systemic lupus erythematosus, were associated with the rs1234314 C/G and rs45454293 C/T polymorphisms of TNFSF4, the rs5839828 C > del and rs36084323 C > T polymorphisms of PDCD1, and the rs28541784C/T, rs200353921A/T, rs3181096C/T, and rs3181098 G/A polymorphisms of CD28. However, the association does not imply causation. These single nucleotide polymorphisms (SNPs) are all located in the promoter region of these genes, so we used the dual-luminescence reporter assay to explore the effect of single nucleotide polymorphisms (SNPs) on transcriptional activity. For each promoter–reporter with a single SNP mutation, more than 10 independent experiments were carried out, and the difference in transcription activity was compared using one-way ANOVA and Tukey’s honestly significant difference test. The results showed that the G-allele of rs1234314 had 0.32 ± 0.09 times the average amount of relative light units (RLU) compared to the C-allele (p = 0.003), the T-allele of rs45454293 had 4.63 ± 0.92 times the average amount of RLU compared to the C-allele (p < 0.001), the del-allele of rs5839828 had 1.37 ± 0.24 times the average amount of RLU compared to the G-allele (p < 0.001), and the T-allele of rs36084323 had 0.68 ± 0.07 times the average amount of RLU compared to the C-allele (p < 0.001). The CD28 SNPs studied here did not affect transcriptional activity. In conclusion, the findings of this study could only confirm that the SNP had a bio-functional effect on gene expression levels. According to the findings, several SNPs in the same gene have bio-functions that affect transcriptional activity. However, some increase transcriptional activity while others decrease it. Consequently, we inferred that the final protein level should be the integration result of the co-regulation of all the SNPs with the effect on transcriptional activity.

Association between single nucleotide polymorphisms within HLA region and disease relapse for patients with hematopoietic stem cell transplantation

Disease relapse occurs in patients with leukemia even hematopoietic stem cell transplantation (HSCT) was performed with human leukocyte antigen (HLA)-matched donors. As revealed previously by Petersdorf et al., there are nine single nucleotide polymorphisms (SNPs) located in the HLA region that potentially modulate the efficacy of HSCT. In this study, we investigated whether or not the genomic variants 500 base pairs flanking the nine transplantation-related SNPs were related to the risk of post-HSCT relapse for patients with leukemia (n = 141). The genomic DNAs collected from 85 patients with acute myeloid leukemia (AML), 56 patients with acute lymphocytic leukemia (ALL), and their respective HLA-matched donors were subject to SNPs analysis, conferred by the mode of mismatch between donor-recipient pair or by recipient or donor genotype analysis. Seven SNPs were revealed to associate with the risk of relapse post-HSCT. For patients with AML, the increased risk of post-HSCT relapse was associated with the donor SNP of rs111394117 in the intron of NOTCH4 gene, and the recipient SNPs of rs213210 in the ring finger protein 1 (RING1) gene promoter, and rs17220087 and rs17213693 in the intron of HLA-DOB gene. For patients with ALL, the increased risk of post-HSCT relapse was associated with the donor SNP of rs213210 in the RING1 gene promoter, and the recipient SNPs of rs79327197 in the HLA-DOA gene promoter, rs2009658 in the telomeric end of lymphotoxin-alpha (LTA) gene, rs17220087 and rs17213693 in the intron of HLA-DOB gene, and rs2070120 in the 3′-UTR of HLA-DOB gene. This study sheds new insight into selecting better candidate donors for performing HSCT in patients with AML and ALL.

Single nucleotide polymorphisms within HLA region are associated with disease relapse for patients with unrelated cord blood transplantation

Disease relapse occurs in unrelated cord blood transplantation (CBT) even when the alleles of human leukocyte antigen (HLA) are fully matched between donor and recipient. This is similar to that observed in other types of hematopoietic stem cell transplantation. Fourteen single nucleotide polymorphisms (SNPs) within the HLA region have been reported previously by Petersdorf et al. and Piras et al. as transplantation determinants in unrelated hematopoietic cell transplantation. In this study, the genomic sequences within 500 base pairs upstream and downstream of the fourteen transplantation-related SNPs from 53 patients and their HLA-matched unrelated donors were analyzed for determining whether or not genetic variants, conferred by either recipient or donor SNP genotype or by recipient-donor SNP mismatching, were associated with the risk of relapse. Seven SNPs were associated with the risk of relapse in unrelated CBT. These included the donor genotype with the SNPs of rs2523675 and rs2518028 at the telomeric end of HCP5 gene, rs2071479 in the intron of the HLA-DOB gene, and rs2523958 in the MICD gene; and the recipient genotype with SNPs of rs9276982 in the HLA-DOA gene, and rs435766 and rs380924 in the MICD gene. As measured by pair-wise linkage disequilibrium (LD) with D′ as the parameter for normalized standard measurement of LD which compares the observed and expected frequencies of one haplotype comprised by alleles at different loci, rs2523675 had high LD with rs4713466 (D′ = 0.86) and rs2523676 (D′ = 0.91) in the HCP5 gene. The rs2518028 had no LD with all other SNPs except rs2523675 (D′ = 0.76). This study provides the basis for developing a method or algorithm for selecting better unrelated CBT candidate donors.

Analysis of a Genetic Polymorphism in the Costimulatory Molecule TNFSF4 with Hematopoietic Stem Cell Transplant Outcomes

Despite stringent procedures to secure the best HLA matching between donors and recipients, life-threatening complications continue to occur after hematopoietic stem cell transplantation (HSCT). Studying single nucleotide polymorphism (SNP) in genes encoding costimulatory molecules could help identify patients at risk for post-HSCT complications. In a stepwise approach we selected SNPs in key costimulatory molecules including CD274, CD40, CD154, CD28, and TNFSF4 and systematically analyzed their association with post-HSCT outcomes. Our discovery cohort analysis of 1157 HLA-A, -B, -C, -DRB1, and -DQB1 matched cases found that patients with donors homozygous for the C variant of rs10912564 in TNFSF4 (48%) had better disease-free survival (P = .029) and overall survival (P = .009) with less treatment-related mortality (P = .006). Our data demonstrate the TNFSF4C variant had a higher affinity for the nuclear transcription factor Myb and increased percentage of TNFSF4-positive B cells after stimulation compared with CT or TT genotypes. However, these associations were not validated in a more recent cohort, potentially because of changes in standard of practice or absence of a true association. Given the discovery cohort, functional data, and importance of TNFSF4 in infection clearance, TNFSF4C may associate with outcomes and warrants future studies.

Cytokine gene polymorphism and graft-versus-host disease: a survey in Iranian bone marrow transplanted patients

Graft versus host disease (GVHD) is a major complication of bone marrow transplantation (BMT). Numerous studies have shown the potential role of cytokine genotypes in the occurrence of GVHD. In this retrospective, case-control study we aimed to investigate the association between 13 cytokine genes and acute GVHD (aGVHD) after HLA-identical sibling BMT in 91 Iranian subjects. Negative association was found between aGVHD and donor IL-10/GCC haplotype or donor IL-4Ra-A allele in the population study. When compared within the leukemia subgroup, we observed positive association between recipient IL-1α -889/C allele and aGVHD. Also there were negative association between recipient IL-10/CAA haplotype and donor IL-4Ra/A allele and development of aGVHD. Among the different genotypes only donor IL-4Ra and donor IL-12 showed significant association. We conclude that several cytokine polymorphisms are positively and negatively associated with aGVHD in Iranian HLA matched siblings, of which IL-4Ra and IL-12 may play important roles.

Severe hyperglycemia immediately after allogeneic hematopoietic stem-cell transplantation is predictive of acute graft-versus-host disease

Stress hyperglycemia and acute graft-versus-host disease (GVHD), the major early complication of hematopoietic stem cell transplantation (HSCT), are both associated with excessive release of inflammatory cytokines. We investigated whether new-onset hyperglycemia immediately after HSCT predicts acute GVHD. We studied nondiabetic adult recipients of human leukocyte antigen-matched HSCT (peripheral blood stem cells) for acute leukemia. Using mean morning serum glucose on Days 1-10, we classified hyperglycemia as: mild (6.11-8.33 mmol/L), moderate (8.34-9.98), and severe (minimum of 9.99). Subjects who were GVHD-free on Day 10 were followed during Days 11-100 for grades II-IV acute GVHD or competing event. Evaluation utilized cumulative incidence-based proportional hazards regression. Subjects (n = 328) were age 18-74, median of 49 years. Per body mass index (BMI)--25.0 % were obese (BMI, 30-48), 33.8 % overweight (25 to <30), 30.8 % normal weight (21 to <25), and 10.4 % lean (18 to <21). Mild, moderate, or severe hyperglycemia occurred during Days 1-10 in 50.0, 21.3, and 16.8 % of subjects, respectively. Cumulative incidence on Day 100 was 44.8 (±2.8) % acute GVHD and 7.9 (±1.5) % competing event. Among normal-to-overweight subjects (n = 212), severe hyperglycemia developed in 14.2 % (n = 30) and more than doubled the risk of acute GVHD (hazards ratio, 2.71; 95 % CI, 1.58-4.65--adjusted for donor/recipient characteristics, prophylactic regimen, and mucositis). In contrast, among obese subjects (n = 82), severe hyperglycemia developed in 30.5 % (n = 25) but did not significantly affect risk of GVHD. (No lean subjects (n = 34) developed severe hyperglycemia.) Hyperglycemia that was less than severe had an effect indistinguishable from normoglycemia. In nondiabetic patients, severe hyperglycemia immediately after allogeneic HSCT indicates increased likelihood of acute GVHD. This association is absent in obese patients, who may be primed by obesity-induced inflammation to develop severe hyperglycemia even without experiencing the cytokine storm that is essential to GVHD pathogenesis.

Genomic studies of GVHD-lessons learned thus far

GVHD remains the most significant complication of hematopoietic SCT, despite advances in HLA matching and the identification of risk various factors. To account for the variation in the incidence and severity of this disease, many genetic association studies have been performed in order to explore the role of immunoregulatory gene polymorphisms. These genes include those that encode cytokines, chemokines, and costimulatory molecules. Polymorphisms in other classes of genes such as those involved in drug metabolism, protein folding, and DNA replication have also been studied. In this review, we address the current knowledge of the role of genetic polymorphisms in GVHD. We also discuss the potential pitfalls inherent in genetic association testing and alternative strategies to address these problems.