IL7RA single nucleotide polymorphisms are associated with the size and function of the MAIT cell population in treated HIV-1 infection.

MAIT cells are persistently depleted and functionally exhausted in HIV-1-infected patients despite long-term combination antiretroviral therapy (cART). IL-7 treatment supports MAIT cell reconstitution in vivo HIV-1-infected individuals and rescues their functionality in vitro. Single-nucleotide polymorphisms (SNPs) of the IL-7RA gene modulate the levels of soluble(s)IL-7Rα (sCD127) levels and influence bioavailability of circulating IL-7. Here we evaluate the potential influence of IL-7RA polymorphisms on MAIT cell numbers and function in healthy control (HC) subjects and HIV-1-infected individuals on long-term cART. Our findings indicate that IL-7RA haplotype 2 (H2*T), defined as T-allele carriers at the tagging SNP rs6897932, affects the size of the peripheral blood MAIT cell pool, as well as their production of cytokines and cytolytic effector proteins in response to bacterial stimulation. H2*T carriers had lower sIL-7Rα levels and higher MAIT cell frequency with enhanced functionality linked to higher expression of MAIT cell-associated transcription factors. Despite an average of 7 years on suppressive cART, MAIT cell levels and function in HIV-1-infected individuals were still significantly lower than those of HC. Notably, we observed a significant correlation between MAIT cell levels and cART duration only in HIV-1-infected individuals carrying IL-7RA haplotype 2. Interestingly, treatment with sIL-7Rα in vitro suppressed IL-7-dependent MAIT cell proliferation and function following cognate stimulations. These observations suggest that sIL-7Rα levels may influence MAIT cell numbers and function in vivo by limiting IL-7 bioavailability to MAIT cells. Collectively, these observations suggest that IL-7RA polymorphisms may play a significant role in MAIT cell biology and influence MAIT cells recovery in HIV-1 infection. The potential links between IL7RA polymorphisms, MAIT cell immunobiology, and HIV-1 infection warrant further studies going forward.

Research Note: Development and characterization of monoclonal antibodies specific for chicken interleukin-7 receptor α (CD127).

CD127, also named interleukin-7 receptor (IL-7R), is expressed on various cell types including naive and memory T cells, and plays a critical role in the differentiation and activation of T lymphocytes. The availability of poultry-specific immune reagents to identify and measure chicken CD127 response will enhance fundamental and applied research in poultry immunology. Mouse monoclonal antibodies (MAbs) against chicken CD127 (chCD127) were developed and characterized. More specifically, a 678 bp ectodomain of chCD127 gene was cloned in the pET28a (+) vector and expressed in BL21-AI E. coli competent cells. The recombinant chCD127 protein with a size of 30 KDa which was also recognized by a mouse anti-human CD127 MAb (Clone G-11) was used to immunize mice, and 6 new mouse MAbs which specifically detected chicken CD127 were developed and characterized. Availability of these new sets of chCD127-specific MAbs will facilitate the immunological studies on CD127 in poultry, especially in understanding effector and memory T immune cell responses in normal and diseased states.

Interleukin-7 and soluble Interleukin-7 receptor levels in type 1 diabetes - Impact of IL7RA polymorphisms, HLA risk genotypes and clinical features.

High soluble IL-7 receptor (sIL-7R) serum levels and associated single nucleotide polymorphisms in the IL7RA gene were found in autoimmune diseases including type 1 diabetes. Further determinants on sIL-7R and IL-7 availability as well as changes during type 1 diabetes disease course remain elusive. Here we performed multiparameter analysis to identify influential genetic and disease-associated factors on sIL-7R and IL-7 serum levels during type 1 diabetes disease course (239 children) and in healthy controls (101 children). We found higher sIL-7R serum concentrations at type 1 diabetes onset and decreasing levels during therapy whereas IL-7 was only higher in long term patients as compared to controls. Multiple linear regression analyses revealed several factors, including IL7RA SNP rs6897932 and HLA risk haplotypes, influencing sIL-7R levels but not IL-7, which was solely associated with the sIL-7R. This study revealed unexpected complexity in the regulation of the sIL-7R but not for IL-7.

Soluble IL-7Rα/sCD127 in Health, Disease, and Its Potential Role as a Therapeutic Agent.

Soluble cytokine receptors can influence immune responses by modulating the biological functions of their respective ligands. These effects can be either agonistic or antagonistic and a number of soluble cytokine receptors have been shown to play critical roles in both maintenance of health and disease pathogenesis. Soluble IL-7Ra (sCD127) is one such example. With its impact on the IL-7/CD127 pathway, which is fundamental for the development and homeostasis of T cells, the role of sCD127 in health and disease has been extensively studied in recent years. Within this review, the role of sCD127 in maintaining host immune function is presented. Next, by addressing genetic factors affecting sCD127 expression and the associated levels of sCD127 production, the roles of sCD127 in autoimmune disease, infections and cancer are described. Finally, advances in the field of soluble cytokine therapy and the potential for sCD127 as a biomarker and therapeutic agent are discussed.

Exploring genetic defects in adults who were clinically diagnosed as severe combined immune deficiency during infancy.

Genetic diagnostic tools including whole-exome sequencing (WES) have advanced our understanding in human diseases and become common practice in diagnosing patients with suspected primary immune deficiencies. Establishing a genetic diagnosis is of paramount importance for tailoring adequate therapeutic regimens, including identifying the need for hematopoietic stem cell transplantation (HSCT) and genetic-based therapies. Here, we genetically studied two adult patients who were clinically diagnosed during infancy with severe combined immune deficiency (SCID). Two unrelated patients, both of consanguineous kindred, underwent WES in adulthood, 2 decades after their initial clinical manifestations. Upon clinical presentation, immunological workup was performed, which led to a diagnosis of SCID. The patients presented during infancy with failure to thrive, generalized erythematous rash, and recurrent gastrointestinal and respiratory tract infections, including episodes of Pneumocystis pneumonia infection and Candida albicans fungemia. Hypogammaglobulinemia and T-cell lymphopenia were detected. Both patients were treated with a 10/10 HLA matched sibling donor unconditioned HSCT. Retrospective genetic workup revealed homozygous bi-allelic mutations in IL7RA in one patient and in RAG2 in the other. Our study exemplifies the impact of retrospectively establishing a genetic diagnosis. Pinpointing the genetic cause raises several issues including optimized surveillance and treatment, understanding disease mechanisms and outcomes, future family planning, and social and psychological considerations.

Assessment of IL-7RA T244I Polymorphism as a Risk Factor of Multiple Sclerosis in Turkish Population.

INTRODUCTION: The T244I variant of the IL-7RA gene, rs6897932, is one of the first polymorphisms found to be associated with the development of multiple sclerosis (MS). Although several studies provided evidence for the association of MS and this variant, other studies could not confirm this result. These inconsistent results suggest that the role of this polymorphism in the development of disease is associated with ethnicity. METHODS: We investigated rs6897932 polymorphisms in a large cohort of patients with MS and healthy controls in a turkish population. RESULTS: In our study, there were no significant differences in genotype frequencies in the IL-7RA rs6897932 polymorphism and no significant difference between C and T alleles in patients with MS and controls. CONCLUSION: This study is the first to evaluate the risk of the rs6897932 polymorphism in turkish patients with MS.

Deleterious and Oncogenic Mutations in the IL7RA.

Interleukin 7 (IL-7) is a critical cytokine that plays a fundamental role in B- and T-cell development and in acute lymphoblastic leukemia (ALL). Its receptor (IL7R) is a transmembrane heterodimer formed by the IL7Rα and the IL2Rγ chain (γc). The IL7R signals through the JAK/STAT pathway. Loss-of-function mutations and some polymorphisms of the IL7Rα were associated to immunodeficiency and inflammatory diseases, respectively. Gain-of-function mutations were described in T-cell ALL and in high risk precursor B-cell ALL. Most confirmed loss-of-function mutations occur in the extracellular part of the IL7Rα while oncogenic mutations are exclusively found in the extracellular juxtamembrane (EJM) or transmembrane regions. Oncogenic mutations promote either IL7Rα/IL7Rα homodimerization and constitutive signaling, or increased affinity to γc or IL-7. This work presents a review on IL7Rα polymorphisms/mutations and attempts to present a classification based on their structural consequences and resulting biological activity.

IL7RA rs6897932 Polymorphism is Associated with Better CD4+ T-Cell Recovery in HIV Infected Patients Starting Combination Antiretroviral Therapy.

Interleukin-7 receptor subunit alpha (IL7RA) rs6897932 polymorphism is related to CD4+ recovery after combination antiretroviral therapy (cART), but no studies so far have analyzed its potential impact in patients with very low CD4+ T-cells count. We aimed to analyze the association between IL7RA rs6897932 polymorphism and CD4+ T-cells count restoration in HIV-infected patients starting combination antiretroviral therapy (cART) with CD4+ T-cells count <200 cells/mm3. We performed a retrospective study in 411 patients followed for 24 months with a DNA sample available for genotyping. The change in CD4+ T-cells count during the follow-up was considered as the primary outcome. The rs6897932 polymorphism had a minimum allele frequency (MAF) >20% and was in Hardy-Weinberg equilibrium (p = 0.550). Of 411 patients, 256 carried the CC genotype, while 155 had the CT/TT genotype. The CT/TT genotype was associated with a higher slope of CD4+ T-cells recovery (arithmetic mean ratio; AMR = 1.16; p = 0.016), higher CD4+ T-cells increase (AMR = 1.19; p = 0.004), and higher CD4+ T-cells count at the end of follow-up (AMR = 1.13; p = 0.006). Besides, rs6897932 CT/TT was related to a higher odds of having a value of CD4+ T-cells at the end of follow-up ≥500 CD4+ cells/mm3 (OR = 2.44; p = 0.006). After multiple testing correction (Benjamini-Hochberg), only the increase of ≥ 400 CD4+ cells/mm3 lost statistical significance (p = 0.052). IL7RA rs6897932 CT/TT genotype was related to a better CD4+ T-cells recovery and it could be used to improve the management of HIV-infected patients starting cART with CD4+ T-cells count <200 cells/mm3.

Reduced expression of the IL7Ra signaling pathway in Neuromyelitis optica.

Neuromyelitis optica (NMO) is a chronic inflammatory demyelinating autoimmune disease of the central nervous system that most commonly affects the optic nerves and spinal cord. To characterize the immunological pathways involved in NMO, whole blood RNA expression array was performed using Nanostring nCounter technology. Two major clusters of genes were found associated with NMO: T cell-associated genes and the TNF/NF-kB signaling pathway. Analysis of the genes within the first cluster confirmed significantly reduced expression of IL7Ra (CD127) in the peripheral blood of NMO patients vs that in healthy controls. IL7Ra upstream transcription factors and its downstream survival signaling pathway were also markedly reduced. In line with the essential role of IL7Ra in T cell maturation and survival, a significantly lower number of naïve T cells, and reduced T cell survival signaling mediated by increased BID (BH3-interacting domain death agonist) expression and increased apoptosis was observed. Cumulatively, these findings indicate that the IL7Ra signaling pathway may play a role in the autoimmune process in NMO.

Interleukin-7 receptor α-chain haplotypes differentially affect soluble IL-7 receptor and IL-7 serum concentrations in children with type 1 diabetes.

BACKGROUND: Interleukin-7 receptor α-chain (IL7RA) haplotypes are associated with susceptibility for development of autoimmune diseases, including type 1 diabetes (T1D). A protective IL7RA haplotype which causes lower soluble IL-7R (sIL-7R) serum levels is hypothesized to restrict IL-7-availability for self-reactive T cells. Functional mechanisms affected by a risk-associated IL7RA haplotype are unknown. METHODS: We investigated the influence of IL7RA haplotypes (tagged by rs6897932T for the protective or by rs1494555G for the risk haplotype) on sIL-7R and IL-7 serum concentrations as well as disease manifestation of children with T1D (n = 259). Possible effects of differential IL-7 serum concentrations on IL-7-mediated in vitro T cell functions (i.e. IL-7R regulation and cytokine expression) were measured in a second study group of children with T1D (n = 42). RESULTS: We detected lower sIL-7R serum concentrations in children with T1D carrying protective or risk haplotypes as compared to reference haplotypes. sIL-7R levels were lowest in T1D children with the protective haplotype and lower IL-7 serum levels were exclusively detected in this study group. We found no evidence for dependency between IL-7 and sIL-7R serum concentrations and no association with T1D manifestation. Neither IL-7 nor sIL-7R serum levels were associated with mIL-7R regulation or IL-7-promoted T cell cytokine expression. CONCLUSIONS: Children with T1D carrying autoimmunity risk- or protection-associated IL7RA haplotypes had both lower sIL-7R serum concentrations as compared to the reference haplotype, but only T1D children with the protective haplotype had lower IL-7 serum levels. Our results suggest additional functional mechanisms of autoimmunity-associated IL7RA variants independent from sIL-7R mediated regulation of IL-7 availability for T cells.

Investigating the exon 6 sequence changes of interleukin 7 receptor A (IL7RA) gene in patients with relapsing-remitting multiple sclerosis.

BACKGROUND: Interleukin 7 receptor alpha (IL7RA) gene that encodes a subunit of IL7 receptor has been reported to be associated with different immunologic disease. OBJECTIVE: Multiple Sclerosis (MS) patients have shown an aberrant blood level of soluble form of IL7R protein. The genomic changes in the sequence of this gene have been suggested to be correlated with its altered splicing specially, variants in the exon 6 of the gene have been reported to influence the maintenance or skipping of this exon and control the soluble or insoluble form of the final product. In order to evaluate this changes in the IL7RA gene and to determine a possible correlation between these changes and the MS susceptibility the whole sequence of the exon 6 and 7 and their flanking sequences were analyzed. METHODS: In this regard, we investigate the sequence changes of the exon 6 and 7 of the IL7RA gene in 75 relapsing-remitting MS patients and compare the results with 75 healthy control using sequence analyzing. RESULTS: The results of the sequence analysis were used in two aspects. The allelic and genotypic estimated frequencies of a reported risk variant rs6897932 in patients and controls in our population confirmed its association with the disease (P= 0.009, OR = 6.273, for TT genotype). Also, we report a possible hazardous cutoff for changes in a potential exon splicing silencer element (ESS (nt. 20-24)) and its correlation with rs6897932 to confer the risk of developing MS. CONCLUSION: In conclusion our results confirm the association between IL7RA exon 6 sequence changes and increased susceptibility for multiple sclerosis.

IL7RA polymorphisms are not associated with AIDS progression.

BACKGROUND: Our aim was to determine whether α-chain of the IL-7 receptor (IL7RA) polymorphisms (rs10491434, rs6897932 and rs987106) are associated with the clinical pattern of AIDS progression in ART-naïve HIV-infected patients. MATERIALS AND METHODS: We carried out a cross-sectional study in 673 HIV-infected patients who were classified into three groups according to the clinical pattern of AIDS progression (188 long-term nonprogressors (LTNPs), 334 moderate progressors (MPs) and 151 rapid progressors (RPs)). Additionally, 134 healthy blood donors participated as a Control-group. We selected three IL7RA polymorphisms located at three regulatory regions [rs6897932 (exon 6), rs987106 (intronic region) and rs10491434 (3'UTR)]. DNA genotyping was performed using Sequenom's MassARRAY platform. RESULTS: The Control-group and all HIV-infected patients had similar age and percentage of males. LTNP-group was older at HIV diagnosis and at the inclusion in the study and had higher percentage of intravenous drug users (IDU) (P < 0·001). Besides, LTNP-group had lower proportion of male patients and homosexual HIV transmission than MP and RP groups (P < 0·001). Moreover, similar values of allelic, genotypic and haplotype frequencies for IL7RA polymorphisms were found between healthy controls and HIV-infected patients (P > 0·05), and among different subgroups of HIV patients according to AIDS progression (LTNPs, MPs and RPs) (P > 0·05). The adjusted logistic regression did not show any significant association between IL7RA polymorphisms and AIDS progression. CONCLUSIONS: IL7RA polymorphisms (rs6897932, rs987106 and rs10491434) were not associated with AIDS progression in Spanish population. Therefore, IL7RA polymorphisms do not seem to help us to understand HIV pathogenesis in untreated HIV-infected patients with different clinical evolution.

The expression of lnc-IL-7R long non-coding RNA dramatically correlated with soluble and membrane-bound isoforms of IL-7Ra gene in multiple sclerosis patients.

BACKGROUND AND PURPOSE: Multiple sclerosis (MS) is a neurological disease of the central nervous system (CNS) that causes physical and cognitive impairments. IL-7Ra is a key non-MHC gene associated with MS. IL-7Ra is a likely functional candidate for this complex disease because it is involved in the development, maturation, and homeostasis of T and B cells. Our aim was to evaluate the expression level and controlling role of lnc-IL-7R in the expression of two variants of IL-7Ra in MS patients versus healthy controls and their correlation with certain clinical features. METHODS: Using the real-time PCR method, we analyzed the expression levels of membrane-bound (IL-7RB) and soluble (IL-7RS) isoforms of IL-7R gene and lnc-IL-7R in 36 MS patients versus 30 healthy controls. RESULTS: Our results revealed no significant difference between the expression levels of IL-7RB and IL-7RS isoforms of IL-7R gene and lnc-IL-7R in MS patients versus healthy controls (p=0.7, p=0.6 and p=0.8, respectively). Moreover, we found a significant correlation between the expression levels of IL-7RB with lnc-IL-7R, IL-7RS with lnc-IL-7R and IL-7RB with IL-7RS in both patient and control groups. CONCLUSIONS: We have probably uncovered new evidence for the controlling role of long non-coding RNAs in the expression level of genes and their roles in MS.

Harnessing the IL-7/IL-7Rα axis to improve tumor immunotherapy.

IL-7 and IL-15 are critical for supporting T cells transferred into a lymphopenic environment. As activated CD8(+) T cells downregulate IL-7Rα, it is thought IL-15 is more important. However, we find that CD8(+) T cells activated with IL-12 have elevated IL-7Rα and rely on IL-7 for persistence and antitumor immunity.

Identification of checkpoints in human T-cell development using severe combined immunodeficiency stem cells.

BACKGROUND: Severe combined immunodeficiency (SCID) represents congenital disorders characterized by a deficiency of T cells caused by arrested development in the thymus. Yet the nature of these developmental blocks has remained elusive because of the difficulty of taking thymic biopsy specimens from affected children. OBJECTIVE: We sought to identify the stages of arrest in human T-cell development caused by various major types of SCID. METHODS: We performed transplantation of SCID CD34(+) bone marrow stem/progenitor cells into an optimized NSG xenograft mouse model, followed by detailed phenotypic and molecular characterization using flow cytometry, immunoglobulin and T-cell receptor spectratyping, and deep sequencing of immunoglobulin heavy chain (IGH) and T-cell receptor δ (TRD) loci. RESULTS: Arrests in T-cell development caused by mutations in IL-7 receptor α (IL7RA) and IL-2 receptor γ (IL2RG) were observed at the most immature thymocytes much earlier than expected based on gene expression profiling of human thymocyte subsets and studies with corresponding mouse mutants. T-cell receptor rearrangements were functionally required at the CD4(-)CD8(-)CD7(+)CD5(+) stage given the developmental block and extent of rearrangements in mice transplanted with Artemis-SCID cells. The xenograft model used is not informative for adenosine deaminase-SCID, whereas hypomorphic mutations lead to less severe arrests in development. CONCLUSION: Transplanting CD34(+) stem cells from patients with SCID into a xenograft mouse model provides previously unattainable insight into human T-cell development and functionally identifies the arrest in thymic development caused by several SCID mutations.

IL7RA polymorphisms predict the CD4+ recovery in HIV patients on cART.

BACKGROUND: The IL7RA polymorphisms have recently been associated with CD4+ T-cell decline in untreated HIV-infected subjects and CD4+ T-cell recovery in patients on combination antiretroviral therapy (cART). The aim of this study was to evaluate whether IL7RA polymorphisms are associated with CD4+ T-cell recovery in HIV-infected patients on long-term cART. STUDY DESIGN: We performed a retrospective study in 151 naïve cART patients with severe immunodeficiency (CD4+ counts ≤200 cells/mm(3) ). IL7RA polymorphisms' genotyping was performed using Sequenom's MassARRAY platform. The outcome variable was the time to achieve the first value of CD4+ count ≥500 cells/mm(3) during the follow-up. RESULTS: Two different trends of CD4+ T-cell recovery were found in Kaplan-Meier analysis. During the first 48 months, 60 of 151 (39·7%) of the patients reached CD4+ T-cell values ≥500 cells/mm(3) , and no differences were observed between IL7RA genotypes. After the first 48 months of follow-up, 27 of 151 (17·8%) of the patients reached CD4+ T-cell values ≥500 cells/mm(3) , with a different pattern of CD4+ recovery depending on IL7RA genotype. Patients with rs10491434 TT genotype and rs6897932 TT genotype were more likely of achieving CD4+ value ≥500 cells/mm(3) than patients with rs10491434 CT/CC genotype (adjusted hazard ratio (aHR) = 3·59; P = 0·005) and patients with rs6897932 CC/CT genotype (aHR = 11·7; P < 0·001). CONCLUSIONS: The IL7RA polymorphisms seem to be associated with CD4+ T-cell recovery in HIV-infected patients who started cART with severe immunodeficiency, in the second phase of CD4+ T-cell recovery after long-term cART.