Abstract: 【Abstract】 Objective To evaluate the protective effect of exogenous biliverdin on ultraviolet B （UVB）-induced photodamage to keratinocytes, and to explore its mechanisms. Methods HaCaT cells were divided into 5 groups: UVB group irradiated with 30 mJ/cm2 UVB alone, 0.1-, 1- and 10-μmol/L UVB groups treated with 0.1, 1, 10 μmol/L biliverdin respectively and irradiated with 30 mJ/cm2 UVB, and control group receiving no treatment. After irradiation, cells in the above groups continued to be cultured for 24 hours. Then, the reactive oxygen species （ROS） level, superoxide dismutase （SOD） activity and malondialdehyde （MDA） content were detected in HaCaT cells, and enzyme-linked immunosorbent assay （ELISA） was performed to detect levels of the inflammatory factors interleukin 6 （IL-6） and IL-8 in HaCaT cells. One-way analysis of variance was used for comparison of means among multiple groups, and least significant difference （LSD）-t test was used for multiple comparisons. Results Significant differences were observed among the UVB group, 0.1-, 1- and 10-μmol/L UVB groups and control group in the ROS levels （3 613.33 ± 206.61, 2 958.67 ± 193.87, 2 678.33 ± 178.24, 2 274.67 ± 118.81, 1 905.67 ± 250.25, respectively, F = 34.02, P < 0.05）, SOD activity （24.41 ± 1.78, 28.96 ± 2.21, 29.75 ± 1.75, 30.19 ± 2.29, 37.52 ± 2.31, respectively, F = 57.36, P < 0.05）, MDA contents （5.61 ± 0.32, 5.46 ± 0.55, 4.65 ± 0.22, 2.55 ± 0.93, 1.31 ± 0.05, respectively, F = 214.09, P < 0.05）, and levels of IL-6 (F = 29.73, P < 0.05) and IL-8 (F = 11.40, P < 0.05). The UVB group showed significantly increased levels of ROS, IL-6 and IL-8, and MDA content compared with the other 4 groups （all P < 0.05）, but significantly decreased SOD activity compared with the other 4 groups （P < 0.05）. Conclusion Exogenous biliverdin has some protective effect on UVB-induced photodamage, likely by reducing oxidative damage to cells, attenuating inflammatory reactions and suppressing lipid peroxidation.

Key words: Ultraviolet rays, Keratinocytes, Biliverdine, Reactive oxygen species, Superoxide dismutase, Malondialdehyde, Interleukin-6, Interleukin-8, Oxidative damage, Inflammatory factors, Lipid peroxidation