Abstract
Schimke immuno-osseous dysplasia (SIOD) is an autosomal recessive, fatal childhood disorder associated with skeletal dysplasia, renal dysfunction, and T-cell immunodeficiency. This disease is linked to biallelic loss-of-function mutations of the SMARCAL1 gene. Although recurrent infection, due to T-cell deficiency, is a leading cause of morbidity and mortality, the etiology of the T-cell immunodeficiency is unclear. Here, we demonstrate that the T cells of SIOD patients have undetectable levels of protein and mRNA for the IL-7 receptor alpha chain (IL7Rα) and are unresponsive to stimulation with IL-7, indicating a loss of functional receptor. No pathogenic mutations were detected in the exons of IL7R in these patients; however, CpG sites in the IL7R promoter were hypermethylated in SIOD T cells. We propose therefore that the lack of IL7Rα expression, associated with hypermethylation of the IL7R promoter, in T cells and possibly their earlier progenitors, restricts T-cell development in SIOD patients.
Keywords:
CD127; CpG; IL7Rα; Promoter DNA methylation; SIOD; T-cell immunodeficiency.
Copyright © 2015 Elsevier Inc. All rights reserved.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adolescent
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Adult
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Arteriosclerosis / genetics*
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Arteriosclerosis / metabolism
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Arteriosclerosis / pathology
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Cells, Cultured
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Child
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Child, Preschool
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DNA Helicases / genetics
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DNA Methylation
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Flow Cytometry
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Gene Expression
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Humans
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Immunohistochemistry
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Immunologic Deficiency Syndromes / genetics*
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Immunologic Deficiency Syndromes / metabolism
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Immunologic Deficiency Syndromes / pathology
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Interleukin-17 / pharmacology
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Leukocytes, Mononuclear / drug effects
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Leukocytes, Mononuclear / metabolism
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Mutation
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Nephrotic Syndrome / genetics*
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Nephrotic Syndrome / metabolism
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Nephrotic Syndrome / pathology
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Osteochondrodysplasias / genetics*
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Osteochondrodysplasias / metabolism
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Osteochondrodysplasias / pathology
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Primary Immunodeficiency Diseases
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Promoter Regions, Genetic / genetics
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Pulmonary Embolism / genetics*
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Pulmonary Embolism / metabolism
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Pulmonary Embolism / pathology
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Receptors, Interleukin-7 / genetics*
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Receptors, Interleukin-7 / metabolism
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Reverse Transcriptase Polymerase Chain Reaction
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Sequence Analysis, DNA
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T-Lymphocytes / metabolism*
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Young Adult
Substances
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Interleukin-17
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Receptors, Interleukin-7
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interleukin-7 receptor, alpha chain
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SMARCAL1 protein, human
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DNA Helicases
Supplementary concepts
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Schimke immunoosseous dysplasia