A hypomorphic mouse model of dystrophic epidermolysis bullosa reveals mechanisms of disease and response to fibroblast therapy
Anja Fritsch, … , Reinhard Fässler, Leena Bruckner-Tuderman
Anja Fritsch, … , Reinhard Fässler, Leena Bruckner-Tuderman
Published April 1, 2008
Citation Information: J Clin Invest. 2008;118(5):1669-1679. https://doi.org/10.1172/JCI34292.
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Research Article Dermatology

A hypomorphic mouse model of dystrophic epidermolysis bullosa reveals mechanisms of disease and response to fibroblast therapy

Abstract

Dystrophic epidermolysis bullosa (DEB) is a severe skin fragility disorder associated with trauma-induced blistering, progressive soft tissue scarring, and increased risk of skin cancer. DEB is caused by mutations in type VII collagen. In this study, we describe the generation of a collagen VII hypomorphic mouse that serves as an immunocompetent animal model for DEB. These mice expressed collagen VII at about 10% of normal levels, and their phenotype closely resembled characteristics of severe human DEB, including mucocutaneous blistering, nail dystrophy, and mitten deformities of the extremities. The oral blistering experienced by these mice resulted in growth retardation, and repeated blistering led to excessive induction of tissue repair, causing TGF-β1–mediated contractile fibrosis generated by myofibroblasts and pseudosyndactyly in the extremities. Intradermal injection of WT fibroblasts resulted in neodeposition of collagen VII and functional restoration of the dermal-epidermal junction. Treated areas were also resistant to induced frictional stress. In contrast, untreated areas of the same mouse showed dermal-epidermal separation following induced stress. These data demonstrate that fibroblast-based treatment can be used to treat DEB in a mouse model and suggest that this approach may be effective in the development of clinical therapeutic regimens for patients with DEB.

Authors

Anja Fritsch, Stefan Loeckermann, Johannes S. Kern, Attila Braun, Michael R. Bösl, Thorsten A. Bley, Hauke Schumann, Dominik von Elverfeldt, Dominik Paul, Miriam Erlacher, Dirk Berens von Rautenfeld, Ingrid Hausser, Reinhard Fässler, Leena Bruckner-Tuderman

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Figure 3

Aberrant mRNA splicing causes reduced expression of collagen VII in Col7a1flNeo/flNeo mice.

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Col7a1flNeo/flNeo mice exhibit growth retardation as a result of malnut...
(A) Collagen VII (ColVII) mRNA expression was analyzed in immortalized keratinocytes of Col7a1WT/WT (lanes 1), Col7a1flNeo/WT (lanes 2), and Col7a1flNeo/flNeo (lanes 3) mice by RT-PCR. Amplification of exon 1–exon 2 showed no difference in expression levels between the genotypes. In contrast, amplification of exon 2–exon 3 revealed aberrant splice variants in Col7a1flNeo/flNeo keratinocytes. Asterisks indicate the normal splice product (***) and the longest aberrant product (**). A transcript variant containing part of the PGK-Neo sequence (*) was identified in Col7a1flNeo/flNeo and Col7a1flNeo/WT cells. (B) Schematic representation of the major transcript variants, the majority of which cannot be translated into protein. The asterisks denote the variants shown in A. Black boxes indicate Col7a1 exons; gray boxes indicate the Neo cassette; bold black arrows indicate the promoter PGK; “Stop” indicates the translational stop of neomycin phosphotransferase; triangles indicate loxP sites; ovals indicate Frt sites. (C) Collagen VII protein levels were analyzed by immunoblotting extracts of dermis, immortalized keratinocytes, and fibroblasts of newborn Col7a1WT/WT (lanes 1), Col7a1flNeo/WT (lanes 2), and Col7a1flNeo/flNeo (lanes 3) mice. Each individual lane contains samples of an independent animal. Collagen VII was detected with the NC2-10 antibody (44). As loading controls, the Coomassie blue–stained band of α1 chain of collagen I (ColI) or immunoblotting with anti–β-tubulin were used. Dermis and cell extracts of Col7a1flNeo/flNeo mice contained strongly reduced amounts of collagen VII.