title: Unraveling the Link Between Ectodermal Disorders and Primary Immunodeficiencies.
abstract: Primary immunodeficiencies (PIDs) include a heterogeneous group of mostly monogenic diseases characterized by functional/developmental alterations of the immune system. Skin and skin annexa abnormalities may be a warning sign of immunodeficiency, since both epidermal and thymic epithelium have ectodermal origin. In this review, we will focus on the most common immune disorders associated with ectodermal alterations. Elevated IgE levels represent the immunological hallmark of hyper-IgE syndrome, characterized by severe eczema and susceptibility to infections. Ectodermal dysplasia (ED) is a group of rare disorders that affect tissues of ectodermal origin. Hypoidrotic ED (HED), the most common form, is inherited as autosomal dominant, autosomal recessive or X-linked trait (XLHED). HED and XLHED are caused by mutations in NEMO and EDA-1 genes, respectively, and show similarities in the cutaneous involvement but differences in the susceptibility to infections and immunological phenotype. Alterations in the transcription factor FOXN1 gene, expressed in the mature thymic and skin epithelia, are responsible for human and murine athymia and prevent the development of the T-cell compartment associated to ectodermal abnormalities such as alopecia and nail dystrophy. The association between developmental abnormalities of the skin and immunodeficiencies suggest a role of the skin as a primary lymphoid organ. Recently, it has been demonstrated that a co-culture of human skin-derived keratinocytes and fibroblasts, in the absence of thymic components, can support the survival of human haematopoietic stem cells and their differentiation into T-lineage committed cells.
authors.affiliation: a Department of Translational Medical Sciences , Federico II University , Naples , Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: D'Assante
authors.affiliation: a Department of Translational Medical Sciences , Federico II University , Naples , Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Fusco
authors.affiliation: a Department of Translational Medical Sciences , Federico II University , Naples , Italy.
authors.forename: Loredana
authors.initials: L
authors.lastname: Palamaro
authors.affiliation: a Department of Translational Medical Sciences , Federico II University , Naples , Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Giardino
authors.affiliation: a Department of Translational Medical Sciences , Federico II University , Naples , Italy.
authors.forename: Vera
authors.initials: V
authors.lastname: Gallo
authors.affiliation: a Department of Translational Medical Sciences , Federico II University , Naples , Italy.
authors.forename: Emilia
authors.initials: E
authors.lastname: Cirillo
authors.affiliation: a Department of Translational Medical Sciences , Federico II University , Naples , Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Pignata
mesh_terms: D000818:Animals; D004062:DiGeorge Syndrome / Q000235:genetics / Q000276:immunology*; D004476:Ectodermal Dysplasia / Q000235:genetics / Q000276:immunology*; D004485:Eczema / Q000276:immunology; D004817:Epidermis / Q000254:growth & development / Q000276:immunology; D006801:Humans; D007589:Job Syndrome / Q000235:genetics / Q000276:immunology*; D051379:Mice; D009154:Mutation; D010641:Phenotype; D016511:Severe Combined Immunodeficiency / Q000235:genetics / Q000276:immunology*; D012867:Skin / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D013950:Thymus Gland / Q000254:growth & development / Q000276:immunology
keywords: FOXN1; T-cell development; ectodermal dysplasia; hyper-IgE; primary immunodeficiencies