Effects of <10-μm Particulate Matter on Cultured Human Sebocytes and Outer Root Sheath Cells and Usefulness of Siegesbeckia Herba Extract

Background: Particulate matter (PM) is one of the air pollutants that can damage human skin; the recent increase in the amount of PM may be detrimental to skin health. Objective: We aimed to investigate the effects of PM on cultured human sebocytes and outer root sheath (ORS) cells and the effects of Siegesbeckia Herba extract (SHE) on PM-treated cultured cells. Methods: Sebocytes and ORS cells were cultured. The cultured cells were treated with various concentrations of PM of <10 μm in size (PM10) (10 μg/ml, 25 μg/ml, 50 μg/ml, and 100 μg/ml) for 24 h. Real-time polymerase chain reaction, measurement of reactive oxygen species (ROS), small interfering (si) RNA transfection, Oil Red O and Nile red staining, and immunofluorescence staining were performed to analyze the presence of inflammatory cytokines, matrix metalloproteinases (MMPs), aryl hydrocarbon receptor (AhR), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), ROS, and lipid production. In addition, PM10 (100 μg/ml)-treated cultured cells were treated with 10 mg/ml of SHE. Results: PM10 upregulates the expression of inflammatory cytokines, MMPs, AhR, NF-kB, and ROS in cultured human sebocytes and ORS cells. The production of ROS was dramatically reduced in AhR siRNA-transfected cells. In addition, PM10 upregulates sebum production in cultured sebocytes. SHE inhibited the upregulation of inflammatory cytokines, MMPs, AhR, NF-kB, ROS, and sebum production in cultured human sebocytes and/or ORS cells by PM10. Conclusion: Effects of PM10 on cultured human sebocytes and ORS cells can be regulated by SH.