Figure 1.

Effect of silymarin on UVB-induced suppression of the CHS response and DNA damage in C3H/HeN mice. (A), Topical treatment of mice with silymarin improves the ability of DCs to induce the CHS response. Donor mice (C3H/HeN) treated with or without silymarin were UVB-irradiated and sensitized with DNFB 24 h after the last UVB exposure. Mice were sacrificed 24 h after sensitization, single-cell suspensions of the lymph nodes were prepared, and CD11c⁺ cells were positively selected using MACS system, as detailed in the Materials and methods. Naïve recipient mice were injected subcutaneously with the CD11c⁺ cells (5× 10⁵) obtained from donor mice. Recipient mice were ear challenged with DNFB 5 days after injection of cells, and the ear thickness was measured before and 24 h after challenge. The change in ear thickness is reported as the mean of millimeters (× 10^-2) ± SD, n=5 per group. *Significantly greater CHS response versus recipient of CD11c⁺ from UVB plus DNFB treated mice, P<0.001; ^¶Significantly lower CHS response versus the positive control (DNFB-sensitized) group, P<0.001. (B), Analysis of CPDs by dot-blot assay. Silymarin repairs UVB-induced DNA damage in vitro in BM-DCs obtained from C3H/HeN mice. BM-DCs were exposed to UVB radiation (5 mJ/cm²) with or without pretreatment with silymarin, harvested either immediately or 24 hours later. Genomic DNA from various treatment groups was isolated and subjected to dot-blot analysis using an antibody specific to CPDs. SLM= silymarin. (C), Treatment of mice with silymarin enhanced the repair of UV-induced DNA damage in epidermal DCs (langerin-positive cells). Langerin-positive cells are shown by red fluorescence and CPD-positive cells are shown by green fluorescence. Arrows indicate langerin-positive or double-positive cells (langerin + CPDs). Representative photomicrographs are shown, n=3/group. Magnification, ×400.