Abstract:
OBJECTIVE To investigate the inhibitory effect of glycyrrhizic acid(GA) on LPS-induced expression of COX-2/PGE
2 in keratinocytes and the melanin production in co-cultured melanocytes explore its possible mechanism.
METHODS Human cutaneous keratinocytes were treated with GA of different concentration(0, 2, 5 and 10 μmol·L
-1) and LPS. The level of cytokine PGE
2 in the culture medium was determined using ELISA kit. The expression of COX-2, NF-κB p-p65, p-IKKα/β and MAPK p-p38 were studied by Western blotting. The melanin content in co-cultured melanocytes was measured by colorimetric method.
RESULTS The expression of COX-2, NF-κB p-p65, p-IKKα/β and MAPK p-p38 in LPS-treated keratinocytes were significantly raised compared to that in control group. LPS also elevated PGE
2 levels in the culture medium. The melanin content in co-cultured melanocytes increased after LPS stimulation. GA decreased COX-2, NF-κB p-p65, p-IKKα/β and MAPK p-p38 expression in LPS-treated keratinocytes in a dose-dependent manner(
P<0.05). GA decreased PGE
2 levels in the culture medium of keratinocytes dose-dependently (
P<0.05). GA also decreased melanin production in co-cultured melanocytes dose-dependently(
P<0.05).
CONCLUSION GA decreases LPS-induced expression of COX-2/PGE
2 in keratinocytes and melanin production in co-cultured melanocytes through suppressing MAPK p38/NF-κB signal pathway.