Effects of Combination of 1,25(OH) 2D 3 and TLR-4 Inhibitor on the Damage to HaCaT Cells Caused by UVB Irradiation

Objective: Vitamin D and Toll-like receptor-4 (TLR-4) inhibition are involved in the protection of keratinocytes. The effects of combination of 1,25(OH) ₂D ₃ and TLR-4 inhibitor on the protection of keratinocytes against ultraviolet radiation B (UVB) irradiation remain unclear. This study was undertaken to explore the effects of combination of 1,25(OH) ₂D ₃ and TAK-242 (TLR-4 inhibitor) on the damage to HaCaT cells caused by UVB irradiation.

Methods: In vitro, HaCaT cells were treated with 1,25(OH) ₂D ₃ or/and TAK-242 prior to UVB irradiation at the intensity of 20 mJ/cm ², then the production of Reactive Oxygen Species (ROS), cell migration, Apoptosis of cells, and the expression of oxidative stress, endoplasmic reticulum stress, and Apoptosis related proteins were determined.

Results: Compared with the HaCaT cells treated with 1,25(OH) ₂D ₃ or TAK-242, the cells treated with both 1,25(OH) ₂D ₃ and TAK-242 showed, 1) significantly lower production of ROS ( P < 0.05); 2) significantly less Apoptosis of HaCaT cells ( P < 0.05); 3) significantly lower expression of NF- κB, Caspase-8, Cyto-C, Caspase-3 ( P < 0.05).

Conclusion: The combination of 1,25(OH) ₂D ₃ and TAK-242 could produce a better protection for HaCaT cells via inhibiting the oxidative stress, endoplasmic reticulum stress and Apoptosis than 1,25(OH) ₂D ₃ or TAK-242 alone.

1,25(OH)2D3; Combined effects; HaCaT cell; Toll-like receptor 4; UVB.