Tape-stripping Barrier Damage Model

Mice were shaved and depilated (Nair) 72 hours prior to barrier damage. Depilation itself did not induce inflammation or damage to the skin barrier by histopathological assessment (Fig. S1). Tape-stripping was performed by applying and removing a Tegaderm bandage (3M) to the depilated dorsal flank skin 10 times, resulting in significant disruption of the epidermis observed as skin reddening and glistening. Mice were allowed to recover from damage and anesthesia in a heated recovery cage and then placed back in their home cage.

To assess barrier damage, transepidermal water loss (TEWL) was measured using a noninvasive probe (Tewameter, C+K). Continuous TEWL measurements for each animal were taken for up to 20s, or until the standard deviation between readings fell below 0.5 g/m²/h. TEWL values immediately following tape-stripping were between 60–80 g/m²/h. TEWL was measured daily following damage and severity score was assessed beginning 48h after damage (prior to 48h no morphological changes in skin were apparent). For consistency, the same experimenter performed all tape-stripping and TEWL measurements. Disease severity score assessed gross morphological changes during healing and included skin thickness (0-3), scale (0-3), and erythema (0-3). To limit duration of daily anesthesia required for both bacterial application and TEWL and score assessment, all manipulations were performed by the same experimenter and thus experimenters could not perform blinded scoring. Mice were euthanized at the end of the experiment by 5% C02 inhalation.