Fig 1.
Acute UVB-exposure induces distinctive pattern of skin epidermal differentiation in A. cahirinus.
A, representative brightfield microscopy images of hematoxylin and eosin-stained skin from control (sham) and UV-irradiated M. musculus and A. cahirinus, collected 24 and 48 hours after exposure. Scale bar = 100 μm. B, quantification of epidermal thickness. sham of both species, n = 3; 24hr M. musculus, n = 6; 24hr A. cahirinus, n = 5; 48hr both species, n = 5. Thickness was calculated as the distance to the outside of the cellular epidermis orthogonal from the basement membrane within the interfollicular space. C, representative immunofluorescence images of epidermal BrdU labeling. The epidermal basement membrane is indicated by the yellow dashed line. Positive cells are indicated by the pink arrows. Scale bar = 25 μm. D and E, quantification BrdU labeling in (D) basal epidermis and (E) suprabasal epidermis. sham of both species, n = 3; 24hr both species, n = 5; 48hr M. musculus, n = 4; 48hr A. cahirinus, n = 5. F, representative immunofluorescence images of epidermal differentiation markers keratin 14 (K14) and keratin 10 (K10) labeling with magnified inset of the interface of both labels. Scale bar = 50 μm. G, quantification of individual differentiation marker layer thickness. n = 3 animals per group. Loricrin images and individual layer comparisons included in S1A–S1E Fig. Data points are biological replicates and lines indicate group means. Bar graphs are mean±SEM. *Significantly different (p<0.05) from the indicated group. #Significantly different (p<0.05) from species sham control. †Significantly different (p<0.05) from M. musculus at the same timepoint.
Fig 2.
Efficient removal of damaged and dying skin epidermal cells through rapid turnover and apoptosis in acute UVB-exposed A. cahirinus.
A, representative immunofluorescence images of epidermal thymine dimer (T-T dimer) labeling of skin from control (sham) and UV-irradiated M. musculus and A. cahirinus, collected 24 and 48 hours after exposure. B and C, quantification of thymine dimer labeling in (B) basal epidermis and (C) suprabasal epidermis. D, representative immunofluorescence images of epidermal γH2AX labeling. E and F, quantification γH2AX labeling in (D) basal epidermis and (E) suprabasal epidermis. G, representative immunofluorescence images of epidermal cleaved caspase-3 (CC3) labeling. Positive cells are indicated by the pink arrows. H and I, quantification of cleaved caspase-3 labeling in (H) basal and (I) suprabasal epidermis. Data points are biological replicates. Lines indicate group means. *Significantly different (p<0.05) from the indicated group. #Significantly different (p<0.05) relative to sham control. †Significantly different (p<0.05) to M. musculus at the same timepoint. The epidermal basement membrane is indicated by the yellow dashed line. All scale bars = 50 μm. For all measurements, n = 3 sham, n = 5 at 24hr and n = 5 at 48hr for each species.
Fig 3.
Attenuated skin epidermal inflammatory response following UV-irradiation in A. cahirinus.
A, representative immunofluorescence images of epidermal HMGB1 labeling of skin from control (sham) and UV-irradiated M. musculus and A. cahirinus, collected 24 and 48 hours after exposure. The epidermal basement membrane is indicated by the yellow dashed line. Scale bar = 50 μm. B and C, quantification of nuclear HMGB1 labeling in (B) basal epidermis and (C) suprabasal epidermis. sham, n = 3 each species; 24hr and 48hr, n = 5 for each species. D, E, F, and G, mRNA expression (ΔCt) of (D) Cxcl1, (E) Il1b, (F) Tgfb1, and (G) Mmp9 in each treatment group as measured by qPCR. For all qPCR: sham, n = 3–4 each species; 24hr n = 5–7 each species; 48hr M. musculus, n = 5–6; 48hr A. cahirinus, n = 3–5 animals per group. Data points are biological replicates and lines indicate group means. *Significantly different (p<0.05) from the indicated group. #Significantly different (p<0.05) relative to sham control. †Significantly different (p<0.05) from M. musculus at the same timepoint.
Fig 4.
Aging associated epidermal thinning, inflammation, and senescence are absent in A. cahirinus.
A, representative brightfield microscopy images of hematoxylin and eosin-stained intact skin from control (Young) and aged (Old) M. musculus and A. cahirinus. Scale bar = 100 μm. B, quantification of epidermal thickness. Thickness was calculated as the distance to the outside of the cellular epidermis orthogonal from the basement membrane within the interfollicular space. C, representative immunofluorescence images of epidermal Lamin B1 labeling of skin from each treatment group. Scale bar = 50 μm. n = 7 Young and n = 8 Old animals of each species. D, quantification of epidermal Lamin B1 labeling. n = 6 Young M. musculus; n = 8 Young A. cahirinus; n = 5 Old M. musculus, n = 6 Old A. cahirinus. E, representative immunofluorescence images of epidermal HMGB1 labeling of skin from each treatment group. Scale bar = 50 μm. F, quantification of epidermal nuclear HMGB1 labeling. n = 6 Young and Old M. musculus; n = 7 Young and Old A. cahirinus. In all immunofluorescent images the epidermal basement membrane is indicated by a yellow dashed line. Data points are biological replicates and lines indicate group means. *Significantly different (p<0.05) from the indicated group.