Effects of Different Components of PM2.5 on the Expression Levels of NF-κB Family Gene mRNA and Inflammatory Molecules in Human Macrophage

Abstract

<i>Background:</i> Studies have found that exposure to fine particulate matter with sizes below 2.5 µm (PM_2.5) might cause inflammation response via the NF-<i>κ</i>B pathway. To date, only a few studies have focused on the toxicity of different components of PM_2.5. We aimed to explore the effects of PM_2.5 with different components on the expression levels of NF-<i>κ</i>B family gene mRNA and inflammatory molecules in human macrophages. <i>Methods:</i> Human monocytic cell line THP-1-derived macrophages were exposed to water-soluble (W-PM_2.5), fat-soluble (F-PM_2.5), and insoluble (I-PM_2.5) PM_2.5. The cell survival rate was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The levels of inflammatory molecules were determined by enzyme-linked immunosorbent assay (ELISA), and the relative mRNA levels of the NF-<i>κ</i>B family gene were determined by real time PCR. <i>Results:</i> PM_2.5 could decrease the cell viability. After exposure to W-PM_2.5, the levels of interleukins (IL)-1β and IL-12 p70 significantly increased. After exposure to F-PM_2.5, the levels of IL-12 p70 significantly increased. The levels of IL-12 p70 and TNF-α after exposure to I-PM_2.5 were significantly higher than that in W- and F-PM_2.5 treatment groups. The levels of IL-8, C reactive protein (CRP), and cyclooxygenase (COX)-2 increased only after exposure to I-PM_2.5. F-PM_2.5 increased the mRNA levels of NF-<i>κ</i>B genes, especially <i>NF</i>-<i>κB₁</i> and <i>RelA</i>. <i>Conclusions:</i> PM_2.5 can decrease the cell survival rate and up-regulate the expression of NF-<i>κ</i>B family gene mRNA and inflammatory molecules. The main toxic components of PM_2.5 related to inflammatory response in macrophages were the I-PM_2.5.