Influence of palmitic acid on the proliferation of and production of inflammatory mediators by a human keratinocyte line HaCaT

Objective To estimate the influence of palmitic acid (PA) on the proliferation of and production of inflammatory mediators by a human keratinocyte line HaCaT.Methods Cultured HaCaT cells were treated with PA of eight concentrations (0-200 μmol/L) for 3-24 hours followed by the evaluation of cell proliferation by using the cell counting kit-8.According to the proliferation assay,four concentrations (75,100,125,150 μmol/L) of PA were selected and used to treat HaCaT cells for 24 hours,then,fluorescence-based immunohistochemical staining was performed to observe the nuclear translocation of nuclear factor (NF)-κB p65,enzyme linked immunosorbent assay (ELISA) to determine the level of interleukin (IL)-6 in the supernatant of culture medium,real-time PCR to detect the mRNA expressions of peroxisome proliferator-activated receptor oα (PPARα) and IL-6,and Western blot to quantify the protein expressions of PPARα as well as total and nuclear NF-κB p65.Those HaCaT cells receiving no treatment served as the control group.Statistical analysis was carried out by one-factor analysis of variance using the GraphPad Prism 5.0 software.Results The HaCaT cells treated with PA of 50-175 μ mol/L showed accelerated proliferation compared with the control HaCaT cells (all P ＜ 0.05).PA from 75 to 150 μmol/L enhanced the nuclear translocation of NF-κB p65,mRNA and protein expressions of PPARα,as well as the mRNA expression and supernatant level of IL-6 in a dose-dependent manner.The relative expression level of nuclear NF-κB p65 protein was 0.4536 ± 0.0173,0.5184 ± 0.0206,0.5333 ± 0.0231,0.6160 ± 0.0297,and the supernatant level of IL-6 was (31.5677 ± 0.2268),(32.3773 ± 0.4156),(32.9837 ± 0.0029) and (33.6890 ± 0.0936) ng/L,in HaCaT cells treated with PA of 75,100,125 and 150 μmol/L,respectively,compared to 0.3237 ± 0.0114 (all P ＜ 0.01) and (30.4577 ± 0.5131) ng/L (all P ＜ 0.01) in the control HaCaT cells,respectively.Conclusions PA can accelerate the proliferation of HaCaT cells,enhance NF-κB nuclear transfer,PPARα expression and IL-6 secretion in a dose-dependent manner within a certain concentration range,and may exert a promoting role in the activation and expression of some inflammatory factors. Key words: Palmitic acid;  Keratinocytes;  Cell proliferation;  NF-kappa B;  Interleukin-6;  PPARα