Fig 4. Elastosis contributes to altered mechanical properties, but not to rougher collagen surface in the photodamaged dermis.

(A) Tropoelastin immunostaining from sun-protected underarm (left panel) and photodamaged forearm dermis (right panel). Images are representative of six subjects. Bar=100μm. 2.5x enlargement of the boxed region is shown. (B) AFM images of sun-protected underarm (left panel) and photodamaged forearm dermis (right panel). Arrowheads indicate elastin fibers. Images are representative of six subjects. Bar=10μm. (C) Verhoff van Geison staining of underarm skin sections before (left) and after (right) treatment with purified neutrophil elastase to remove elastotic materials. Images are representative of six subjects. Bars = 100μm. (D) Before (left) and after (right) removal of dermal elastosis. Verhoff van Geison staining of photodamaged forearm skin sections before (left) and after (right) treatment with purified neutrophil elastase to remove elastotic materials. Images are representative of six subjects. Bars = 100μm. (E) Collagen fibril surface roughness, (F) Stiffness, and (G) Hardness before and after removal of elastotic material. Results are expressed as the mean ± SEM. Each group comprised six subjects, a total of nine indents were measured from per subject. *p < 0.05. (H) Alteration of LOX family mRNA expression in the photodamaged human skin in vivo. Skin dermis was prepared by cutting off epidermis at a depth of 1 mm by cryostat. Total RNA was extracted from the dermis and the expression of LOX family mRNA was quantified by real-time RT-PCR. LOX family mRNA levels were normalized to the housekeeping gene 36B4, as an internal control for quantification, and expressed relative to the underarm. Mean±SEM. Each group comprised six subjects. *p < 0.05.