Protective effect of exogenous biliverdin against ultraviolet B-induced photodamage in HaCaT cells

Abstract

Objective To evaluate the protective effect of exogenous biliverdin on ultraviolet B (UVB) -radiated HaCaT cells, and to explore its mechanism. Methods Cultured HaCaT cells were divided into 5 groups: control group receiving no treatment, UVB group irradiated with 30 mJ/cm2 UVB, 3 biliverdin+ UVB groups treated with 100 nmol/L, 1 μmol/L and 10 μmol/L biliverdin respectively for 1 hour followed by 30 mJ/cm2 UVB radiation. After 24-hour treatment, changes in the morphology of HaCaT cells were observed, and cell counting kit 8 (CCK8) assay was performed to determine cell survival rates in the above groups. Western blot analysis was conducted to measure the protein expression of antioxidant signaling molecule NF-E2-related factor-2 (Nrf-2) and the photodamage signaling molecules matrix metalloproteinase-1 (MMP-1) and MMP-3. Results CCK8 assay showed that the survival rate of HaCaT cells was significantly lower in the UVB group than in the control group (P < 0.05) , but significantly higher in the 100-nmol/L, 1-μmol/L and 10-μmol/L biliverdin+ UVB groups than in the UVB group (all P < 0.05) . Western blot analysis showed that the protein expression of MMP-1 and MMP-3 was significantly higher in the UVB group (1.150 ± 0.187, 0.979 ± 0.054 respectively) than in the control group (0.116 ± 0.018, 0.636 ± 0.035 respectively; both P < 0.01) , but was significantly lower in the 100-nmol/L, 1-μmol/L and 10-μmol/L biliverdin + UVB groups (MMP-1: 0.825 ± 0.139, 0.313 ± 0.047 and 0.286 ±0.036 respectively; MMP-3: 0.888 ± 0.017, 0.672 ± 0.042 and 0.569 ± 0.037 respectively) than in the UVB group (all P < 0.05) . Moreover, the protein expression of Nrf-2 was significantly lower in the UVB group (0.906 ± 0.034) than in the control group (1.242 ± 0.141, P < 0.05) , but significantly higher in the 100-nmol/L, 1-μmol/L and 10-μmol/L biliverdin+ UVB groups (1.556 ± 0.112, 1.897 ± 0.234 and 2.035 ± 0.274) than in the UVB group (all P < 0.01) . Conclusion Exogenous biliverdin protects against UVB-induced photodamage in HaCaT cells, which may be associated with Nrf-2 antioxidant signaling pathway. Key words: Keratinocytes; Ultraviolet rays; Biliverdin; Matrix metalloproteinase 1; Matrix metallo-proteinase 3; NF-E2-related factor 2; HaCaT cells