Figure 1. Tissue damage and double stranded RNA activate TLR3 to promote wound-induced hair follicle neogenesis (WIHN).

A) Confocal Scanning Laser Microscopy (CSLM) images for C57BL6J (Low Regeneration, “LR”) and Mixed B6/FVB/SJL (High Regeneration, “HR”) strains of mice. Area of WIHN shown within red box. Original image size is 4mm².

B) Venn diagram depicting significant overlap between genes associated with high levels of follicle regeneration in mouse skin (in vivo) and human keratinocytes treated with poly (I:C) in vitro published by Karim et al., 2011 under GSE21260.

C) Mean fold change in TLR3 mRNA in healed scars at WD20-24 in LR vs. HR mice as determined by qRT-PCR and normalized to housekeeping gene β-actin.

D) Mean fold change in TLR3 mRNA four hours post scratch assay in NHEK as determined by qRT-PCR and normalized to housekeeping gene RPLP0.

E) WIHN levels in wt mice after standard straight cut or “fringe cut” to wound edge; n = 14–15 mice. Area of WIHN shown within red box. Original image size is 4mm².

F) Regenerated hair shafts (white, arrows) in healed wounds after single injection of poly (I:C) (500ng) or control at WD3 and visualized by dissecting microscope at ~WD58-62.

G) Cross-sectional H&E histology through the middle of healed scar at WD22 after single injection of poly (I:C) as in 1F. Regenerated hair follicles are marked with arrows. Scale bar = 500um.

H) WIHN levels in wt mice after poly (I:C) (500ng) or PBS control measured by CSLM, n = 10–11 mice.

I) WIHN levels in wt mice after RNase III (15 units) or buffer control measured by CSLM, n = 17–19 mice.

J) WIHN levels in strain-matched wt control mice and TLR3 KO mice measured by CSLM n = 6 mice.

K) WIHN in TLR3 KO mice after poly (I:C) (500ng) compared to PBS control measured by CSLM; n = 9 mice.

*p < 0.05 by Student’s T-test or Single Factor ANOVA.