Congenital deficiency reveals critical role of ISG15 in skin homeostasis
Muhammad Nasir Hayat Malik, … , Thomas Werfel, Frank Pessler
Muhammad Nasir Hayat Malik, … , Thomas Werfel, Frank Pessler
Published November 30, 2021
Citation Information: J Clin Invest. 2022;132(3):e141573. https://doi.org/10.1172/JCI141573.
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Research Article Autoimmunity

Congenital deficiency reveals critical role of ISG15 in skin homeostasis

Abstract

Ulcerating skin lesions are manifestations of human ISG15 deficiency, a type I interferonopathy. However, chronic inflammation may not be their exclusive cause. We describe two siblings with recurrent skin ulcers that healed with scar formation upon corticosteroid treatment. Both had a homozygous nonsense mutation in the ISG15 gene, leading to unstable ISG15 protein lacking the functional domain. We characterized ISG15–/– dermal fibroblasts, HaCaT keratinocytes, and human induced pluripotent stem cell–derived vascular endothelial cells. ISG15-deficient cells exhibited the expected hyperinflammatory phenotype, but also dysregulated expression of molecules critical for connective tissue and epidermis integrity, including reduced collagens and adhesion molecules, but increased matrix metalloproteinases. ISG15–/– fibroblasts exhibited elevated ROS levels and reduced ROS scavenger expression. As opposed to hyperinflammation, defective collagen and integrin synthesis was not rescued by conjugation-deficient ISG15. Cell migration was retarded in ISG15–/– fibroblasts and HaCaT keratinocytes, but normalized under ruxolitinib treatment. Desmosome density was reduced in an ISG15–/– 3D epidermis model. Additionally, there were loose architecture and reduced collagen and desmoglein expression, which could be reversed by treatment with ruxolitinib/doxycycline/TGF-β1. These results reveal critical roles of ISG15 in maintaining cell migration and epidermis and connective tissue homeostasis, whereby the latter likely requires its conjugation to yet unidentified targets.

Authors

Muhammad Nasir Hayat Malik, Syed Fakhar-ul-Hassnain Waqas, Jana Zeitvogel, Jingyuan Cheng, Robert Geffers, Zeinab Abu-Elbaha Gouda, Ahmed Mahrous Elsaman, Ahmed R. Radwan, Matthias Schefzyk, Peter Braubach, Bernd Auber, Ruth Olmer, Mathias Müsken, Lennart M. Roesner, Gisa Gerold, Sven Schuchardt, Sylvia Merkert, Ulrich Martin, Felix Meissner, Thomas Werfel, Frank Pessler

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Figure 3

Proteomic analysis reveals major dysregulation in connective tissue homeostasis in ISG15–/– fibroblasts after IFN-α stimulation.

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Proteomic analysis reveals major dysregulation in connective tissue home...
Immortalized dermal fibroblasts carrying either the native ISG15 locus (WT) or a naturally occurring loss-of-function mutation (ISG15–/–) were stimulated with IFN-α (1000 IU/mL) for 24 hours and subjected to global proteome analysis (n = 4). (A) Principal component analysis demonstrating clear separation between WT and ISG15–/– cells based on their protein expression patterns. (B and C) Enrichment analysis based on the proteome data used as input for A. GO terms relating to IFN responses, other inflammatory processes, and stress responses are enriched in ISG15–/– cells (B), whereas GO terms relating to epidermal and connective tissue/extracellular matrix homeostasis are depleted in ISG15–/– cells (C). X axes show Benjamini-Hochberg adjusted P values (–log10) for enrichment/depletion; only GO terms with adjusted P less than 0.05 are shown. (D) Hierarchical clustering of differentially abundant (adjusted P < 0.05) proteins showing upregulation of proinflammatory proteins, HLA molecules, and MMP1 but downregulation of collagen constituents and ROS scavengers in ISG15–/– cells.