Effects of Collagen Tripeptide Supplement on Photoaging and Epidermal Skin Barrier in UVB-exposed Hairless Mice

Abstract

Collagen tripeptide (CTP) is a functional food material with several biological effects such as improving dry skin and wound and bone fracture healing. This study focused on the anti-photoaging effects of CTP on a hairless mouse model. To evaluate the effects of CTP on UVB-induced skin wrinkle formation in vivo, the hairless mice were exposed to UVB radiation with oral administration of CTP for 14 weeks. Compared with the untreated UVB control group, mice treated with CTP showed significantly reduced wrinkle formation, skin thickening, and transepidermal water loss (TEWL). Skin hydration and hydroxyproline were increased in the CTP-treated group. Moreover, oral administration of CTP prevented UVB-induced MMP-3 and -13 activities as well as MMP-2 and -9 expressions. Oral administration of CTP increased skin elasticity and decreased abnormal elastic fiber formation. Erythema was also decreased in the CTP-treated group. Taken together, these results strongly suggest that CTP has potential as an anti-photoaging agent.

Keywords: collagen tripeptide (CTP); matrix metalloproteinases (MMPs); photoaging; transepidermal water loss (TEWL); wrinkle formation.

Fig. 1

Body weight changes in UVB-irradiated hairless mice. Mice were administered CTP for 14 weeks and concurrently exposed to UVB radiation three times a week. Control, vehicle +non-UVB irradiated; UVB control, vehicle+UVB irradiated; CTP-167, 167 mg/kg/day CTP+UVB irradiated; CTP- 333, 333 mg/kg/day CTP+UVB irradiated. Data are expressed as mean±SD of five mice in each group.

Fig. 2

Effects of orally administered CTP on wrinkle formation in UVB-irradiated hairless mice (photographs and gross appearance). The dorsal skin surface of hairless mice was exposed to UVB three times a week for 14 weeks. Before sacrifice, photographs were taken from the dorsal areas of hairless mice.

Fig. 3

Effects of oral administration of CTP on wrinkle formation in UVB-irradiated hairless mice (wrinkle values). The dorsal skin surface of hairless mice was exposed to UVB three times a week for 14 weeks. Wrinkle values were obtained from the surface of skin replica. Data are expressed as mean±SD of five mice in each group. ^##p<0.01 compared with non-UVB irradiated mice; ^**p<0.01 compared with UVB-irradiated mice.

Fig. 4

Effects of CTP administered orally on skin thickness in UVB-irradiated hairless mice. (A) Skin tissue sections were stained with H&E. (B) Skinfold thickness was measured with a caliper mid-way between the neck and hips at 14 weeks. Data are expressed as mean±SD of five mice in each group. ^##p<0.01 compared with non-UVB irradiated mice; ^**p<0.01 compared with UVB-irradiated mice.

Fig. 5

Effects of orally administrated CTP on skin barrier function in UVB-irradiated hairless mice. (A) Skin hydration and (B) TEWL as markers of skin barrier function were measured by Corneometer^® and Tewameter^® three days before the animals were sacrificed. Data are expressed as mean±SD of five mice in each group. ^##p<0.01 compared with non-UVB irradiated mice; ^**p<0.01 compared with UVB-irradiated mice.

Fig. 6

Effects of oral administration of CTP on collagen fibers in UVB-irradiated hairless mice. (A) Skin tissue sections were stained with Masson’s trichrome stain for collagen fibers. (B) Amount of hydroxyproline was estimated after UVB irradiation for 14 weeks. Data are expressed as mean±SD of five mice in each group. ^##p<0.01 compared with non-UVB irradiated mice; ^**p<0.01 compared with UVB-irradiated mice.

Fig. 7

Effects of CTP administered orally on UVB-induced MMP-3 and -13 expressions in UVB-irradiated hairless mice. The mRNA levels (A) and protein levels (B) of MMP-3 and -13 were determined by RT-PCR and Western Blot analysis, respectively. Data are expressed as mean±SD of five mice in each group. ^##p<0.01 compared with non-UVB irradiated mice; ^**p<0.01 compared with UVB-irradiated mice.

Fig. 8

Effects of oral administration of CTP on UVB-induced MMP-2 and -9 in UVB-irradiated hairless mice. The amounts of MMP-2 and -9 activities in equal amounts of protein lysates were analyzed by gelatin zymography. Data are expressed as mean±SD of five mice in each group. ^##p<0.01 compared with non-UVB irradiated mice; ^*p<0.05, ^**p<0.01 compared with UVB-irradiated mice.

Fig. 9

Effects of orally administered CTP on elasticity in UVB-irradiated hairless mice. (A) Effects of CTP on gross elasticity (Ua/Uf) of skin were measured by Cutometer^®. (B) Elastic fibers in the dermis were stained with Verhoeff’s stain. Data are expressed as mean±SD of five mice in each group. ^##p<0.01 compared with non-UVB irradiated mice; ^**p<0.01 compared with UVB-irradiated mice.

Fig. 10

Effects of oral administration of CTP on erythema formation in UVB-irradiated hairless mice. After UV irradiation for 14 weeks, erythema was determined by Mexameter^®. Data are expressed as mean±SD of five mice in each group. ^##p<0.01 compared with non-UVB irradiated mice; ^**p<0.01 compared with UVB-irradiated mice.