Association of Donor and Recipient Interleukin-1 Gene Single Nucleotide Polymorphisms with Outcome after Allogeneic Hematopoietic Stem Cell Transplantation in Childhood

Background: Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment approach for hematological malignancies, genetic diseases, and severe immune deficiencies. Despite the matching of the human leucocyte antigens (HLA), HSCT is still associated with a considerable rate of morbidity and mortality caused by infections, relapse, and graft-versus-host disease (GVHD). Therefore, non-HLA polymorphisms like cytokines and their receptors are considered as important contributing factors. Interleukin-1 (IL-1) is a cytokine that initiates and maintains the immune response as well as the development of GVHD in the recipient. Single nucleotide polymorphisms (SNPs) of the IL-1 gene are associated with a higher risk of malignancies, an elevated death rate because of infections, and a higher chance to suffer from autoimmune or chronic diseases. This study aimed to analyze the association of IL-1 gene SNPs with outcome in a pediatric population undergoing allogeneic HSCT.

Methods: We included 270 pediatric patients with a median age of 9 years who underwent an allogeneic HSCT and their respective donors. We used TaqMan real-time polymerase chain reaction to analyze the SNPs IL-1-alpha rs1800587 (-889, A/T), IL-1-beta rs1143627 (-31, A/T), and IL-1-beta rs16944 (-511, A/T). The underlying diseases were acute lymphoblastic leukemia (n=89), acute myeloid leukemia (n=63), chronic myeloid leukemia (n=10), juvenile myelomonocytic leukemia (n=9), myelodysplastic syndrome (n=29), lymphoma (n=7), solid tumor (n=11), genetic disease (n=41), and aplastic anemia (n=11). The stem cell sources were bone marrow (n=178), peripheral blood (n=90) or umbilical cord blood (n=2). Two hundred donors were HLA-matched, and 70 donors were HLA-mismatched. Conditioning regimen was myeloablative in all cases and based on chemotherapy in 180 children or total body irradiation in 90 children. The predominant post-transplant immunosuppression was cyclosporine A and methotrexate in 148 patients or cyclosporine A alone in 55 patients. The genotyped SNPs were compared using the Kaplan-Meier method for event-free survival (EFS) and overall survival (OS) and the Gray test for acute GVHD, chronic GVHD, relapse rate (RR), and transplant-related mortality (TRM).

Results: We observed a significant association between the SNP IL-1-alpha rs1800587 (-889, A/T) of the donor and the rate of acute GVHD. The genotypes of IL-1-alpha rs1800587 had the following distributions in the donor: CC genotype n=132 (49%), CT genotype n=114 (42%), and TT genotype n=24 (9%). Overall, 63 children (23%) suffered from moderate to severe acute GVHD (grade II-IV). We found a significantly increased incidence of moderate to severe acute GVHD (grade II-IV) if the patient was transplanted from a donor with the CC/CT genotype compared to the TT genotype (25% versus 4%; p=0.028). We found no significant associations of the SNP IL-1-alpha rs1800587 (-889, A/T) for chronic GVHD, RR, TRM, EFS, and OS. In addition, we observed no significant associations of the other studied genotypes IL-1-beta rs16944 (-511, A/T) and rs1143627 (-31, A/T) in either donors or recipients for acute and chronic GVHD, RR, TRM, EFS, and OS.

Conclusion: Our study identified the IL-1-alpha rs1800587 CC/CT genotype of the donor as a genetic risk factor for the development of moderate to severe acute GVHD (grade II-IV) in pediatric allogeneic HSCT recipients. After confirmation in further studies, these findings could implicate the adjustment of prophylactic measures to reduce the risk of acute GVHD in children.