Preventive/improving effect on photo-aging of skin (in vivo)
For verifying the effect of oral ingestion of CTP-containing collagen against photo-aging of the skin, we studied anti-wrinkle effect in UV-B irradiation model system (Hairless mouse).
Test for the effect against photo-aging of skin
1) Methods
Irradiation of UV-B to hairless mice test groups was done 3 times a week. It started with a 75 mJ/cm2 dose of irradiation in the 1st week, and continued for 14 weeks with the dose increasing by 1 MED (minimal erythema dose) a week. During the period, we analyzed digital images of skin samples which were collected from the following 4 groups; the "CTP-167 mg/kg" group, the "CTP-333 mg/kg" group (those groups were administered CTP-containing collagen orally of 167 mg/kg and 333 mg/kg per day, respectively), the "UVB control" group (No administration of CTP), and the "Control" group (No UV-B irradiation and No administration of CTP). The subcutaneous tissues were measured by a caliper, and those tissue slices were stained with Hematoxylin-Eosin (HE) stain. The collagen fibers were applied with Masson�s trichrome stain. TEWL, an index of skin barrier function, was measured by a Teweameter®. The activities of MMP-2 and MMP-9 induced by UV-B irradiation were measured by the Gelatin Zymography method.
2) Results
The oral administration of CTP-containing collagen significantly inhibited skin wrinkle formation induced by UV-B irradiation of hairless mouse (Figure 1). Furthermore, it was verified that CTP inhibited TEWL of the skin which got damaged by UV-B irradiation by enhancing a barrier function of the skin, and inhibited expression of activities of gelatinase (MMP-2 and MMP-9) at mRNA level or protein expression level (Figure 2). In addition, it was found that CTP restored the collagen fibers and the amount of collagen which were destroyed and reduced by UV-B irradiation (Figure 3), and increased skin elasticity deteriorated by UV-B irradiation and reduced abnormal formation of elastin fibers at the same time.
Figure 1: Effect against skin wrinkle formation
Figure 2: Effect against MMP-2 and MMP-9 expressions
Figure 3: Effect on collagen fiber
Figure 4: Effect on elastin fiber
4) Discussion
As a result of above studies, we can expect that ingestion of CTP-containing collagen will reduce damages to skin like wrinkle formation caused by UV, and be help with early recovery from the damage.
