Abstract
Poly-D,L-lactic acid (PDLLA) filler, which increases volume and collagen synthesis, is used for skin rejuvenation. PDLLA filler also increases M2 macrophages and IL-10. Ultraviolet (UV) radiation induces dermal hyperpigmentation by disrupting the basement membrane (BM), allowing melanin to move into the dermis. Therefore, using UV-irradiated macrophages and animal skin, we determined whether PDLLA filler decreased M1 macrophages and skin inflammation, thereby reducing BM destruction and dermal hyperpigmentation. UV radiation increased the M1 macrophage marker CD86 and TNF-α expression, which was inhibited by the treatment of macrophages with PDLLA. In fibroblasts treated with conditioned medium from UV-irradiated macrophages, NF-κB activity, NLRP3 inflammasome components (NLRP3, ASC, and pro-caspase-1), IL-18, MMP2, and MMP9 increased, but all decreased after PDLLA treatment. Similar to the in vitro study, UV-irradiated mouse skin showed increased CD86, NLRP3, ASC, pro-caspase-1, MMP2, and MMP9, which decreased after PDLLA injection. Disruption of the lamina densa of the BM and dermal pigmentation increased after UV irradiation and decreased after PDLLA injection. In conclusion, PDLLA reduced dermal pigmentation by decreasing BM destruction in UV-irradiated skin. PDLLA has the potential to reduce dermal pigmentation by regenerating the BM.