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Dinges SS, Amini K, Notarangelo LD, Delmonte OM. Primary and secondary defects of the thymus. Immunol Rev 2024; 322:178-211. [PMID: 38228406 PMCID: PMC10950553 DOI: 10.1111/imr.13306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
The thymus is the primary site of T-cell development, enabling generation, and selection of a diverse repertoire of T cells that recognize non-self, whilst remaining tolerant to self- antigens. Severe congenital disorders of thymic development (athymia) can be fatal if left untreated due to infections, and thymic tissue implantation is the only cure. While newborn screening for severe combined immune deficiency has allowed improved detection at birth of congenital athymia, thymic disorders acquired later in life are still underrecognized and assessing the quality of thymic function in such conditions remains a challenge. The thymus is sensitive to injury elicited from a variety of endogenous and exogenous factors, and its self-renewal capacity decreases with age. Secondary and age-related forms of thymic dysfunction may lead to an increased risk of infections, malignancy, and autoimmunity. Promising results have been obtained in preclinical models and clinical trials upon administration of soluble factors promoting thymic regeneration, but to date no therapy is approved for clinical use. In this review we provide a background on thymus development, function, and age-related involution. We discuss disease mechanisms, diagnostic, and therapeutic approaches for primary and secondary thymic defects.
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Affiliation(s)
- Sarah S. Dinges
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
- Department of Pediatric Respiratory Medicine, Immunology and Critical Care Medicine, Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Kayla Amini
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Luigi D. Notarangelo
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ottavia M. Delmonte
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Demir E, Adım F, Döğen ME, Aydoğdu A, Yeşil E, Mermer S, Başer B, Ürel Demir G. EXTL3-Associated Immunoskeletal Dysplasia with Neurodevelopmental Abnormalities: A Lethal Phenotype. PEDIATRIC ALLERGY, IMMUNOLOGY, AND PULMONOLOGY 2023; 36:147-149. [PMID: 38010729 DOI: 10.1089/ped.2023.0079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Background: Immunoskeletal dysplasia with neurodevelopmental abnormalities (ISDNA) caused by Exostosin-Like Glycosyltransferase 3 (EXTL3) biallelic mutations is a very rare syndrome with only 16 cases reported in the literature. Skeletal dysplasia, neurodevelopmental delay, immunodeficiency, liver, and kidney cysts are the most common findings of this syndrome. Case Presentation: Here, we report on a patient who exhibited a lethal phenotype with clinical characteristics of this syndrome and had a homozygous pathogenic mutation in EXTL3 gene. Conclusions: ISDNA should be kept in mind in the differential diagnosis of patients presenting with neuro-immuno-skeletal dysplasia phenotype.
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Affiliation(s)
- Engin Demir
- Division of Pediatric Gastroenterology, Department of Pediatrics, Mersin City Training and Research Hospital, Mersin, Turkey
| | - Filiz Adım
- Department of Pediatrics, Mersin City Training and Research Hospital, Mersin, Turkey
| | | | - Ayşe Aydoğdu
- Division of Pediatric Allergy and Immunology, Department of Pediatrics, Mersin City Training and Research Hospital, Mersin, Turkey
| | - Edanur Yeşil
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Mersin City Training and Research Hospital, Mersin, Turkey
| | - Serdar Mermer
- Department of Medical Genetics, Mersin City Training and Research Hospital, Mersin, Turkey
| | - Burak Başer
- Department of Medical Genetics, Mersin City Training and Research Hospital, Mersin, Turkey
| | - Gizem Ürel Demir
- Division of Pediatric Genetics, Department of Pediatrics, Mersin City Training and Research Hospital, Mersin, Turkey
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Wilson LFL, Dendooven T, Hardwick SW, Echevarría-Poza A, Tryfona T, Krogh KBRM, Chirgadze DY, Luisi BF, Logan DT, Mani K, Dupree P. The structure of EXTL3 helps to explain the different roles of bi-domain exostosins in heparan sulfate synthesis. Nat Commun 2022; 13:3314. [PMID: 35676258 PMCID: PMC9178029 DOI: 10.1038/s41467-022-31048-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/31/2022] [Indexed: 11/08/2022] Open
Abstract
Heparan sulfate is a highly modified O-linked glycan that performs diverse physiological roles in animal tissues. Though quickly modified, it is initially synthesised as a polysaccharide of alternating β-D-glucuronosyl and N-acetyl-α-D-glucosaminyl residues by exostosins. These enzymes generally possess two glycosyltransferase domains (GT47 and GT64)-each thought to add one type of monosaccharide unit to the backbone. Although previous structures of murine exostosin-like 2 (EXTL2) provide insight into the GT64 domain, the rest of the bi-domain architecture is yet to be characterised; hence, how the two domains co-operate is unknown. Here, we report the structure of human exostosin-like 3 (EXTL3) in apo and UDP-bound forms. We explain the ineffectiveness of EXTL3's GT47 domain to transfer β-D-glucuronosyl units, and we observe that, in general, the bi-domain architecture would preclude a processive mechanism of backbone extension. We therefore propose that heparan sulfate backbone polymerisation occurs by a simple dissociative mechanism.
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Affiliation(s)
- L F L Wilson
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, 22903, USA
| | - T Dendooven
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - S W Hardwick
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - A Echevarría-Poza
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
| | - T Tryfona
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
| | - K B R M Krogh
- Department of Protein Biochemistry and Stability, Novozymes A/S, Krogshøjvej 36, 2880, Bagsværd, Denmark
| | - D Y Chirgadze
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - B F Luisi
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1GA, UK
| | - D T Logan
- Biochemistry and Structural Biology, Centre for Molecular Protein Science, Department of Chemistry, Lund University, SE-221 00, Lund, Sweden
| | - K Mani
- Department of Experimental Medical Science, Division of Neuroscience, Glycobiology Group, Lund University, SE-221 00, Lund, Sweden.
| | - P Dupree
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
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