Collagen VII Half-Life at the Dermal-Epidermal Junction Zone: Implications for Mechanisms and Therapy of Genodermatoses

Abstract

The tissue half-life of proteins largely determines treatment frequency of non-gene-editing-based therapies targeting the cause of genodermatoses. Surprisingly, such knowledge is missing for a vast number of proteins involved in pathologies. The dermal-epidermal junction zone is believed to be a rather static structure, but to our knowledge no detailed analysis of the stability of proteins within this zone has been performed. Here, we addressed the in vivo half-life of collagen type VII using genetic ablation of its expression and therapeutic introduction of exogenous collagen VII in a preclinical model. A similar in vivo stability of collagen VII was observed in the skin, tongue, and esophagus, with a half-life of about 1 month. Collagen VII expressed by intradermally injected mesenchymal stromal cells also exhibited a similar half-life. Our study provides key information needed for the development of protein replacement or cell-based therapies for dystrophic epidermolysis bullosa caused by genetic deficiency of collagen VII. Moreover, by showing what we define as an intermediate half-life of collagen VII, our study challenges the view of the dermal-epidermal junction zone as a static structure with very slow turnover.

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“…In accordance with the previously established half-life of collagen VII (38), tamoxifen treatment led to a significant loss of collagen VII in skin and spleen after >10 wk (Fig. 5 A and B).…”

“…It is important to point out that this effect was achieved in absence of, and preceded, significant breach of skin integrity (Fig. 5A) (38).…”

“…For these analyses, we used an equal number of female and male mice to account for potential gender-specific responses. The timing of swab sample collection in tamoxifen-inducible Col7a1 knockout mice after Col7a1 ablation and in RDEB mice after collagen VII injections, was chosen based on knowledge of collagen VII tissue half-life and the dynamic of collagen VII deposition at the dermal-epidermal junction zone after delivery into tissue (38). Sample size was estimated on the variance from initial analysis by performing a log-rank test with a power of 80% and for a value of P < 5%.…”

“…RDEB mice and wild-type littermates were on a mixed C57BL/6:129sv background, and tamoxifen-inducible Col7a1 knockout mice were on C57BL/ 6 background (3,38). For deletion of Col7a1 in tamoxifen-inducible knockout mice, 4-wk-old mice received i.p.…”

“…2 μg of tamoxifen dissolved in corn oil on 5 consecutive days. The excision efficiency was analyzed by PCR on DNA from tail biopsies collected after completion of tamoxifen treatment as previously described (38). Control mice received injections with corn oil alone.…”