Interleukin 7

Interleukin 7 (IL-7) is a protein^[5] that in humans is encoded by the IL7 gene.^[6][7][8]

IL7
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 3DI2, 3DI3
Identifiers
Aliases	IL7, IL-7, interleukin 7
External IDs	OMIM: 146660; MGI: 96561; HomoloGene: 680; GeneCards: IL7; OMA:IL7 - orthologs
Gene location (Human) Chr. Chromosome 8 (human)[1] Band 8q21.13 Start 78,675,743 bp[1] End 78,805,523 bp[1]
Gene location (Mouse) Chr. Chromosome 3 (mouse)[2] Band 3 A1|3 2.02 cM Start 7,635,054 bp[2] End 7,678,820 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in sperm bronchial epithelial cell testicle Achilles tendon jejunal mucosa lower lobe of lung caput epididymis lymph node right uterine tube rectum Top expressed in secondary oocyte lumbar spinal ganglion zygote primary oocyte endothelial cell of lymphatic vessel thymus mesenteric lymph nodes left colon Paneth cell stroma of bone marrow More reference expression data BioGPS More reference expression data
Gene ontology Molecular function protein binding interleukin-7 receptor binding growth factor activity cytokine receptor binding cytokine activity Cellular component extracellular space extracellular region collagen-containing extracellular matrix Biological process negative regulation of catalytic activity cell-cell signaling negative regulation of extrinsic apoptotic signaling pathway positive regulation of organ growth negative regulation of apoptotic process bone resorption humoral immune response immune response positive regulation of cell population proliferation animal organ morphogenesis regulation of gene expression homeostasis of number of cells within a tissue negative regulation of extrinsic apoptotic signaling pathway in absence of ligand T cell lineage commitment positive regulation of B cell proliferation positive regulation of T cell differentiation interleukin-7-mediated signaling pathway regulation of signaling receptor activity positive regulation of cytokine-mediated signaling pathway cytokine-mediated signaling pathway positive regulation of chemokine production regulation of peptidyl-tyrosine phosphorylation positive regulation of gene expression positive regulation of B cell differentiation Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 3574 16196 Ensembl ENSG00000104432 ENSMUSG00000040329 UniProt P13232 P10168 RefSeq (mRNA) NM_000880 NM_001199886 NM_001199887 NM_001199888 NM_008371 NM_001313888 NM_001313889 NM_001313890 RefSeq (protein) NP_000871 NP_001186815 NP_001186816 NP_001186817 NP_001300817 NP_001300818 NP_001300819 NP_032397 Location (UCSC) Chr 8: 78.68 – 78.81 Mb Chr 3: 7.64 – 7.68 Mb PubMed search [3] [4]
Wikidata
View/Edit Human View/Edit Mouse

IL-7 is a hematopoietic growth factor secreted by stromal cells in the bone marrow and thymus. It is also produced by keratinocytes,^[9] follicular dendritic cells,^[10] hepatocytes,^[11] neurons, and epithelial cells,^[12] but is not produced by normal lymphocytes.^[13] A study also demonstrated how the autocrine production of the IL-7 cytokine mediated by T-cell acute lymphoblastic leukemia (T-ALL) can be involved in the oncogenic development of T-ALL and offer novel insights into T-ALL spreading. ^[14]

Structure

The three-dimensional structure of IL-7 in complex with the ectodomain of IL-7 receptor has been determined using X-ray diffraction.^[15]

Function

Lymphocyte maturation

IL-7 stimulates the differentiation of multipotent (pluripotent) hematopoietic stem cells into lymphoid progenitor cells (as opposed to myeloid progenitor cells where differentiation is stimulated by IL-3).^{[citation needed]} It also stimulates proliferation of all cells in the lymphoid lineage (B cells, T cells and NK cells).^{[citation needed]} It is important for proliferation during certain stages of B-cell maturation, T and NK cell survival, development and homeostasis.^{[citation needed]}

IL-7 is a cytokine important for B and T cell development. This cytokine and the hepatocyte growth factor (HGF) form a heterodimer that functions as a pre-pro-B cell growth-stimulating factor. This cytokine is found to be a cofactor for V(D)J rearrangement of the T cell receptor beta (TCRß) during early T cell development.^[16] This cytokine can be produced locally by intestinal epithelial and epithelial goblet cells, and may serve as a regulatory factor for intestinal mucosal lymphocytes.^{[citation needed]} Knockout studies in mice suggested that this cytokine plays an essential role in lymphoid cell survival.^[17]

IL-7 signaling

IL-7 receptor and signaling, common γ chain (blue) and IL-7 receptor-α (green)

IL-7 binds to the IL-7 receptor, a heterodimer consisting of Interleukin-7 receptor alpha and common gamma chain receptor.^[18] Binding results in a cascade of signals important for T-cell development within the thymus and survival within the periphery. Knockout mice which genetically lack IL-7 receptor exhibit thymic atrophy, arrest of T-cell development at the double positive stage, and severe lymphopenia. Administration of IL-7 to mice results in an increase in recent thymic emigrants, increases in B and T cells, and increased recovery of T cells after cyclophosphamide administration or after bone marrow transplantation.

Disease

Cancer

IL-7 promotes hematological malignancies (acute lymphoblastic leukemia, T cell lymphoma).^[19]

Viral Infections

Elevated levels of IL-7 have also been detected in the plasma of HIV-infected patients.^[20]

Clinical application

IL-7 as an immunotherapy agent has been examined in many pre-clinical animal studies and more recently in human clinical trials for various malignancies and during HIV infection.^[13][21]

Cancer

Recombinant IL-7 has been safely administered to patients in several phase I and II clinical trials. A human study of IL-7 in patients with cancer demonstrated that administration of this cytokine can transiently disrupt the homeostasis of both CD8+ and CD4+ T cells with a commensurate decrease in the percentage of CD4+CD25+Foxp3+ T regulatory cells.^[22] No objective cancer regression was observed, however a dose limiting toxicity (DLT) was not reached in this study due to the development of neutralizing antibodies against the recombinant cytokine.

HIV infection

Associated with antiretroviral therapy, IL-7 administration decreased local and systemic inflammations in patients that had incomplete T-cell reconstitution. These results suggest that IL-7 therapy can possibly improve the quality of life of those patients.^[23]

Transplantation

IL-7 could also be beneficial in improving immune recovery after allogenic stem cell transplant.^[24]