Single-Nucleotide Polymorphisms Within Non-HLA Regions Are Associated With Engraftment Effectiveness for Patients With Unrelated Cord Blood Transplantation

Abstract

Clinically, stem cells with matched human leukocyte antigens (HLAs) must be selected for allogeneic transplantation to avoid graft rejection. However, adverse reactions still occur after cord blood transplantation (CBT). It was inferred that the HLA system is not the only regulatory factor that may influence CBT outcomes. Therefore, we plan to investigate whether the single-nucleotide polymorphisms (SNPs) located in non-HLA genes are associated with the effectiveness of CBT. In this study, the samples of 65 donors from CBT cases were collected for testing. DNA sequencing was focused on the SNPs of non-HLA genes, cytotoxic T-lymphocyte-associated protein 4 (CTLA4), CD28, tumor necrosis factor ligand superfamily 4 (TNFSF4), and programmed cell death protein 1 (PDCD1), which were selected in regard to the literatures published in 2017 and 2018, which indicated that they were related to stem cell transplantation. Then, in combination with the detailed follow-up transplantation tracking database, these SNPs were analyzed with the risk of mortality, relapse, cytomegalovirus (CMV) infection, and graft-versus-host disease (GVHD). We found that there were 2 SNPs of CTLA4, 1 SNP of TNFSF4, and 2 SNPs of PDCD1 associated with the effectiveness of unrelated CBT. These statistically significant SNPs and haplotypes would be used in clinical to choose the best donor for the patient receiving CBT. Moreover, the polygenic risk scores (PRSs) with these SNPs could be used to predict the risk of CBT adverse reactions with an area under the receiver operating characteristic curve (AUC) of 0.7692. Furthermore, these SNPs were associated with several immune-related diseases or cancer susceptibility, which implied that SNPs play an important role in immune regulation.

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

“…TNFSF4 expression is known to drive T-cell proliferation, differentiation, and cytokine production [ 35 ]. Thus, the higher promoter activity of rs1234314 with the C-allele and rs45454293 with the T-allele was consistent with our previously published findings that suggest that they increase the risk of GVHD III-IV after HSCT in AML patients, as well as the risk of mortality after CBT [ 28 , 29 ]. Furthermore, Tripathi et al discovered in 2019 that the OX40L(TNFSF4)-OX40 interaction on T cells was linked to the induction and development of acute GVHD (aGVHD) in HSCT, and that treatment with anti-human OX40L mAb could effectively prevent and reduce the severity of aGVHD [ 36 ].…”

“…Grafts with the rs1234314 C-allele had a 7.39-fold increased risk of GVHD III-IV compared with the G-allele ( p = 0.011), and the rs45454293 T-allele had a 4.86-fold increased risk of GVHD III-IV compared with the C-allele ( p = 0.010). In a CBT research study [ 28 ], rs1234314 of the TNFSF4 gene was associated with mortality after CBT ( p < 0.001), and having the CC genotype increased the risk of mortality by 15.4 times. In SLE research analysis [ 30 ], the genotype frequency (CC vs. CG vs. GG) of rs1234314 was significantly different between cases and controls ( p = 0.005).…”

“…Previous research on the relationship between SNPs and HSCT outcomes [ 29 ] found that the C-allele of rs36084323 in the promoter region of the PDCD1 gene in donors was associated with a higher risk of CMV ( p = 0.0265) and relapse ( p = 0.0356) in ALL patients, while the G-allele of rs5839828 ( p = 0.0265) increased the risk of relapse in ALL patients. According to analysis of the effectiveness of CBT [ 28 ], when the graft carried at least one T-allele in rs36084323, the CBT case had a 4.2 times greater risk of relapse (95% CI = 1.331–13.320, p = 0.012). For SLE [ 30 ], it was shown that the T-allele of rs36084323 provided a protective effect.…”

“…For a detailed PCR program and the primers used for amplifying the promoter regions of CD28 , PDCD1 , and TNFSF4 , please refer to ref. [ 28 , 29 , 30 ].…”

“…We previously discussed the association between SNPs of the CD28 , TNFSF4 , and PDCD1 genes and the outcomes of post-cord blood transplantation (CBT) and HSCT and the development of SLE [ 28 , 29 , 30 ], finding that many SNPs located in the promoter region had statistically significant differences. However, the association does not imply causation.…”