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.
View: Text | PDF
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

×

Figure 2

Histological and genetic features.

Options: View larger image (or click on image) Download as PowerPoint
Histological and genetic features. (A) Selected histological findings (P...
(A) Selected histological findings (P1). Left: H&E stains from a biopsy of an active skin lesion demonstrating intercellular edema (spongiosis; arrow) and parakeratosis reminiscent of an eczematous lesion. Middle and right: H&E stains from a biopsy of a chronic lesion demonstrating psoriasiform epidermal hyperplasia (box) and perivascular infiltration (arrows). Scale bars: 100 μm. (B) Results of whole exome sequencing: The index cases are homozygous for a nonsense mutation c.288C>G, which is predicted to lead to a truncated ISG15 protein missing the active domain. Sequencing depth of the WT and/or mutant allele in each family member is shown in Supplemental Table 2. (C) IHC staining for ISG15 protein with a primary antibody directed against the C-terminus (aa 136–165). There is strong expression in epidermis and in dermal blood vessels in control tissue, which is absent in the index case (chromogen: DAB, brown). Nonspecific rabbit IgG was used as negative control. Scale bars: 100 μm. (D) The truncated ISG15 protein resulting from the c.288C>G mutation is unstable. ISG15–/– fibroblasts were transfected with plasmids expressing WT or c.288C>G ISG15 coding sequences and tested for expression of ISG15 by immunoblot using an antibody directed against amino acids 1–150, thus also recognizing the NH2-terminus. A band of the expected migration of the truncated protein is not seen (arrow).