The role of interleukin-15 polymorphisms in adult acute lymphoblastic leukemia

IL-15 Prevents the Development of T-ALL from Aberrant Thymocytes with Impaired DNA Repair Functions and Increased NOTCH1 Activation

We previously reported that NOD.Scid mice lacking interleukin-15 (IL-15), or IL-15 receptor alpha-chain, develop T-acute lymphoblastic leukemia (T-ALL). To understand the mechanisms by which IL-15 signaling controls T-ALL development, we studied the thymocyte developmental events in IL-15-deficient Scid mice from NOD and C57BL/6 genetic backgrounds. Both kinds of mice develop T-ALL characterized by circulating TCR-negative cells expressing CD4, CD8 or both. Analyses of thymocytes in NOD.Scid.Il15^-/- mice prior to T-ALL development revealed discernible changes within the CD4^-CD8^- double-negative (DN) thymocyte developmental stages and increased frequencies of CD4⁺CD8⁺ double-positive cells with a high proportion of TCR-negative CD4⁺ and CD8⁺ cells. The DN cells also showed elevated expressions of CXCR4 and CD117, molecules implicated in the expansion of DN thymocytes. T-ALL cell lines and primary leukemic cells from IL-15-deficient NOD.Scid and C57BL/6.Scid mice displayed increased NOTCH1 activation that was inhibited by NOTCH1 inhibitors and blockers of the PI3K/AKT pathway. Primary leukemic cells from NOD.Scid.Il15^-/- mice survived and expanded when cultured with MS5 thymic stromal cells expressing Delta-like ligand 4 and supplemented with IL-7 and FLT3 ligand. These findings suggest that IL-15 signaling in the thymus controls T-ALL development from aberrant thymocytes with an impaired DNA repair capacity and increased NOTCH1 activation.

The role of interleukin-15 in the development and treatment of hematological malignancies

Cytokines are a vital component of the immune system that controls the activation and growth of blood cells. However, chronic overexpression of cytokines can trigger cellular events leading to malignant transformation. The cytokine interleukin-15 (IL-15) is of particular interest, which has been shown to contribute to the development and progression of various hematological malignancies. This review will provide an overview of the impact of the immunopathogenic function of IL-15 by studying its role in cell survival, proliferation, inflammation, and treatment resistance. We will also review therapeutic approaches for inhibiting IL-15 in blood cancers.

Identification of prognostic genes in the acute myeloid leukemia microenvironment

The tumor microenvironment (TME) has a strong influence on the progression, therapeutic response, and clinical outcome of acute myeloid leukemia (AML), one of the most common hematopoietic malignancies in adults. In this study, we identified TME-related genes associated with AML prognosis. Gene expression profiles from AML patients were downloaded from TCGA database, and immune and stromal scores were calculated using the ESTIMATE algorithm. Immune scores were correlated with clinical features such as FAB subtypes and patient’s age. After categorizing AML cases into high and low score groups, an association between several differentially expressed genes (DEGs) and overall survival was identified. Functional enrichment analysis of the DEGs showed that they were primarily enriched in the immune response, inflammatory response, and cytokine activity, and were involved in signaling processes related to hematopoietic cell lineage, B cell receptor, and chemokine pathways. Two significant modules, dominated respectively by CCR5 and ITGAM nodes, were identified from the PPI network, and 20 hub genes were extracted. A total of 112 DEGs correlated with poor overall survival of AML patients, and 11 of those genes were validated in a separate TARGET-AML cohort. By identifying TME-associated genes, our findings may lead to improved prognoses and therapies for AML.

IFNG +874 A/T is associated with acute lymphoblastic leukemia in Mexican Mestizos

Acute lymphoblastic leukemia (ALL), the most common type of cancer in children worldwide, has one of the highest incidence rates in Mexico. It is a multifactorial disease and different cytokine single nucleotide polymorphisms (SNP), have been associated with ALL expression. Few studies have been published analyzing IFNG +874 T/A and IL2 -330 G/T in this type of leukemia. These SNPs are involved in high or low expression, and are central to cellular immunity, influencing greatly tumor growth. The purpose of this work was to explore the association of IFNG +874 A/T (rs2430561) and IL2 -330 G/T (rs2069762) SNPs with ALL susceptibility and/or protection in 488 Mexican Mestizos patients, as compared to 950 Mexican Mestizo healthy controls. The results demonstrated that IFNG +874 T allele (pc = 0.00004, OR = 0.673) and the TT genotype (pc = 0.00015, OR = 0.349), protect against ALL expression with no specific gender association; however, the TT homozygote genotype (vs. TA+AA) seems more protective in males (pc = 0.00683). IL2 -330 G/T does not contribute to the development of ALL. In healthy Mexicans, the most common genotypes for IL2 and IFNG, are the low cytokine producers, suggesting that the genetic background in this ethnic group, may be partly responsible for the high incidence of ALL. These results show for the first time in Mexicans, the relevant role that IFNG SNP has in the genetic etiology of ALL. Thus, a large group of patients belonging to different ethnicities will be very helpful to study in order to demonstrate if these SNPs contribute to the genetic etiology of ALL, as shown here in Mexican Mestizos.

Influence of IL15 gene variations on the clinical features, treatment response and risk of developing childhood acute lymphoblastic leukemia in Latvian population

Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. Modern treatment protocols allow achievement of long-term event-free survival rates in up to 85% of cases, although the treatment response varies among different patient groups. It is hypothesized that treatment response is influenced by the IL15 gene variations, although research results are conflicting. To analyze IL15 gene variations influence treatment response, clinical course and the risk of developing ALL we performed a case-control and family-based study. The study included 81 patients with childhood ALL. DNA samples of both or one biological parent were available for 62 of ALL patients and 130 age and gender adjusted healthy samples were used as a control group. Analyzed IL15 gene variations: rs10519612, rs10519613 and rs17007695 were genotyped using PCR-RFLP assay. Our results shows that IL15 gene variations haplotypes are associated with the risk of developing childhood ALL (p < 0.05), although there is no such association for the variations separately. The variations rs10519612 and rs1059613 in a recessive pattern of inheritance were associated with hyperdiploidy (p = 0.048). Analyzed genetic variations had no impact on other clinical features and treatment response (assessed by the minimal residual disease) in our study.

The Role of the Central Nervous System Microenvironment in Pediatric Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common cancer in children. While survival rates for ALL have improved, central nervous system (CNS) relapse remains a significant cause of treatment failure and treatment-related morbidity. Accordingly, there is a need to identify more efficacious and less toxic CNS-directed leukemia therapies. Extensive research has demonstrated a critical role of the bone marrow (BM) microenvironment in leukemia development, maintenance, and chemoresistance. Moreover, therapies to disrupt mechanisms of BM microenvironment-mediated leukemia survival and chemoresistance represent new, promising approaches to cancer therapy. However, in direct contrast to the extensive knowledge of the BM microenvironment, the unique attributes of the CNS microenvironment that serve to make it a leukemia reservoir are not yet elucidated. Recent work has begun to define both the mechanisms by which leukemia cells migrate into the CNS and how components of the CNS influence leukemia biology to enhance survival, chemoresistance, and ultimately relapse. In addition to providing new insight into CNS relapse and leukemia biology, this area of investigation will potentially identify targetable mechanisms of leukemia chemoresistance and self-renewal unique to the CNS environment that will enhance both the durability and quality of the cure for ALL patients.

Inherited genetic variation in childhood acute lymphoblastic leukemia

Although somatically acquired genomic alterations have long been recognized as the hallmarks of acute lymphoblastic leukemia (ALL), the last decade has shown that inherited genetic variations (germline) are important determinants of interpatient variability in ALL susceptibility, drug response, and toxicities of ALL therapy. In particular, unbiased genome-wide association studies have identified germline variants strongly associated with the predisposition to ALL in children, providing novel insight into the mechanisms of leukemogenesis and evidence for complex interactions between inherited and acquired genetic variations in ALL. Similar genome-wide approaches have also discovered novel germline genetic risk factors that independently influence ALL prognosis and those that strongly modify host susceptibility to adverse effects of antileukemic agents (eg, vincristine, asparaginase, glucocorticoids). There are examples of germline genomic associations that warrant routine clinical use in the treatment of childhood ALL (eg, TPMT and mercaptopurine dosing), but most have not reached this level of actionability. Future studies are needed to integrate both somatic and germline variants to predict risk of relapse and host toxicities, with the eventual goal of implementing genetics-driven precision-medicine approaches in ALL treatment.

A promoter polymorphism (rs3806798) of interleukin-15 gene is associated with chronic hepatitis B virus infection in the Chinese Han population

This study aimed to investigate the association between the polymorphisms of IL-15 gene and susceptibility to chronic hepatitis B virus (HBV) infection in the Chinese Han population. A total of 234 patients with chronic HBV infection and 150 age- and sex-matched healthy controls in the Chinese population were enrolled in this case-control study. Genotyping of ten single nucleotide polymorphisms (SNPs) in the IL-15 gene was carried out via Sequenom MassARRAY system. The association analysis demonstrated that SNP rs3806798 (A/T) had a significant difference in the distribution between patients and healthy controls (P = 0.033). Moreover, a significantly increased risk of HBV infection was found to be associated with IL-15 rs3806798 A allele among male patients and HBeAg-negative patients, compared with IL-15 rs3806798 T allele (P = 0.003; P = 0.046, respectively). Furthermore, haplotype analysis revealed that haplotype ATAGG (rs3806798, rs12508866, rs1519551, rs6819823 and rs2857261, respectively) in block 1 was significantly associated with HBV infection (P = 0.022). In conclusion, we found an association between IL-15 rs3806798 and the risk of chronic HBV infection in a sample of Chinese Han population.

Interleukin 15 receptor alpha rs2228059 A > C polymorphism decreased risk of gastric cardiac adenocarcinoma in a Chinese population

Gastric cardiac adenocarcinoma (GCA) is one of the common malignant tumors in the world and has a high incidence in China. Both environmental risk factors and genetic factors might play an essential role in the GCA carcinogenesis. We performed a hospital-based case-control study to evaluate the genetic effects of interleukin 15 (IL15) and IL15 receptor alpha (IL15RA) functional single nucleotide polymorphisms (SNPs) on the pathogenesis of GCA. A total of 243 GCA cases and 476 controls were enrolled in this study. The genotypes were determined using a custom-by-design 48-Plex SNPscan(TM) Kit. When the IL15RA rs2228059 AA homozygote genotype was used as the reference group, the CC genotype was correlated with a significantly decreased risk for GCA (CC vs. AA: adjusted OR = 0.61, 95 % CI = 0.37-0.98, p = 0.042). Our results revealed that functional variant IL15RA rs2228059 A > C might attenuate individual's risk of GCA. However, there was no significant association between the other five IL15 SNPs and GCA susceptibility. This present study demonstrated that IL15RA rs2228059 A > C polymorphism might modify GCA susceptibility. The results were based on a limited sample size; future larger studies with more rigorous designs are warranted to validate our findings.

Influence of interleukin-15 polymorphism on the survival of adult patients with acute lymphoblastic leukemia in Egypt

The aim of this study was to analyze the association of the rs10519612 and rs17007695 polymorphisms with the risk of acute lymphoblastic leukemia (ALL) and also to evaluate their impact on the survival of adult patients with ALL. The study included 164 adult patients with ALL and 158 healthy subjects as a control group who were genotyped for the interleukin-15 (IL-15) gene using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. We observed a higher risk of developing ALL for rs10519612 CC, rs17007695 TC and rs17007695 CC genotype carriers. There was increased risk for T-cell type in patients with the rs10519612 CC genotype. Notably, increased risk to develop B-cell type was found with rs17007695 TC and CC genotypes. There was no impact on overall survival or disease-free survival at 3 years. It is concluded that there is an association between both gene polymorphisms and the risk of ALL and with disease immunophenotype. However, there was no impact on the outcome of patients.

Interleukin-15 enhances cellular proliferation and upregulates CNS homing molecules in pre-B acute lymphoblastic leukemia

Genome-wide association studies have consistently implicated the interleukin-15 (IL-15) gene in acute lymphoblastic leukemia (ALL) biology, including associations with disease susceptibility, and increased risk of central nervous system (CNS) involvement. However, whether pre-B ALL blasts directly respond to IL-15 is unknown. Here, we show that most pre-B ALL primary samples and cell lines express IL-15 and components of its receptor and that primary pre-B ALL cells show increased growth in culture in response to IL-15. Investigation of mechanisms of action using IL-15-responsive SD-1 cells shows this growth advantage is maximal under low-serum conditions, mimicking those found in cerebrospinal fluid. IL-15 also upregulates PSGL-1 and CXCR3, molecules associated with CNS trafficking. Investigation of downstream signaling pathways indicates that IL-15 induces signal transducer and activator of transcription 5 (STAT5), extracellular signal-regulated kinase (ERK) 1/2, and to a lesser extent phosphatidylinositol 3-kinase (PI3K) and nuclear factor κB (NF-κB) phosphorylation. The IL-15-mediated growth advantage is abolished by mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK), PI3K, and NF-κB inhibitors but preserved in the presence of STAT5 inhibition. Together, these observations provide a mechanistic link between increased levels of IL-15 expression and leukemogenesis, high-risk disease, and CNS relapse and suggest potential therapeutic targets.

Association of interleukin-15 single nucleotide polymorphisms with resistance to brucellosis among Iranian patients

Interleukin (IL)-15, a Th1-related cytokine, triggers inflammatory cells' recruitment and increases the expression of interferon gamma (IFN-γ), which is an important cytokine in the immunity against brucellosis. Different single-nucleotide polymorphisms (SNPs) have been observed in the IL-15 gene, so this study aimed to investigate the probable association between these SNPs and susceptibility to brucellosis among Iranian patients. A total of 190 patients with brucellosis and 83 healthy milk farmers who consumed contaminated raw milk and dairy products from animals involved with brucellosis were included in this study. All the patients and the controls were genotyped for four IL-15 polymorphisms at positions 267, 367, 13687 and 14035 using polymerase chain reaction-restriction fragment length polymorphisms. The 267C and 13687A alleles, haplotypes CGCT and CAAA and the 267CC and 13687AA genotypes were significantly more frequent in the controls than in the patients (P = 0.014, 0.03, 0.006, 0.024, 0.026 and 0.01, respectively), so the variation in the IL-15 gene may be one of the factors affecting the resistance to brucellosis. In contrast, the frequency of haplotypes CGCA and TACT was significantly higher in patients compared with controls (P = 0.015 and 0.007, respectively), and interestingly the last one was observed only in the patients; therefore, it may serve as a predictive factor for brucellosis. In conclusion, it could be suggested that IL-15 genetic variants can affect resistance or susceptibility to human brucellosis among Iranian patients.