Fig. 5.

Ablation of collagen VII in adult mice leads to loss of cochlin from spleen and increased bacterial skin colonization before affecting skin integrity. (A) Back skin from tamoxifen-inducible Col7a1 knockout mice 12 wk after injection with tamoxifen or corn oil (vehicle). (Top and Middle) Sections stained for collagen VII (green) and nuclei visualized with DAPI (blue). (Bottom) H&E staining showing no apparent dermal–epidermal separation in vehicle- or tamoxifen-treated mice. (Scale bars, 100 μm.) (B) Spleen from tamoxifen-inducible Col7a1 knockout mice and controls 12 wk after knockout induction. Sections stained for collagen VII (red) or cochlin (green, goat polyclonal antibody), as indicated. Shown are a low responder (35% residual collagen VII compared with vehicle-treated controls) and a high responder (20% residual collagen VII compared with vehicle-treated controls), as determined by ImageJ-based quantification of antibody staining intensity for collagen VII on five spleen sections (38). (Scale bars, 100 μm.) (C) Plot of collagen VII abundance vs. cochlin abundance quantified by immunofluorescence staining as described in B. Linear regression analysis reveals a good correlation (r² = 0.74) of collagen VII vs. cochlin content. (D–F) Ablation of collagen VII in adult mice results in increased bacterial colonization. Bacterial swabs from forepaws of mice treated as in A. (D) Photos of representative LB-agar plates. (E) Quantification of number of bacterial colonies per plate; n = 8; **P = 0.0015, significance tested with Mann–Whitney U test. Values represent mean ± SEM. Five tamoxifen-treated mice showed highly and three slightly increased bacterial colonization, virtue of different knockout efficiency. (F) Plot of collagen VII abundance vs. bacterial colonies. Linear regression analysis reveals a good negative correlation (r² = 0.81) of collagen VII abundance vs. bacterial colonies.