Figure 2.

The expression of toll-like receptors (TLRs) (I), cytokines (II), and chemokines (III) after 72 h of single particulate matter (PM) stimulation. The protein levels of toll-like receptors (TLRs), cytokines, and chemokines were determined by enzyme-linked immunosorbent assay. (A) The heat-treated PM₁₀ $\left({\text{PM}}_{\text{10}}^{-}\right)$ group, (B) the non-heat-treated PM₁₀ $\left({\text{PM}}_{\text{10}}^{+}\right)$ group, (C) the heat-treated PM_2.5 $\left({\text{PM}}_{\text{2.5}}^{-}\right)$ group, and (D) the non-heat-treated PM_2.5 $\left({\text{PM}}_{\text{2.5}}^{+}\right)$ group. Data are presented as means ± SEs. Different letters indicate significant differences (p < 0.05) of mean value among the four experimental groups. The experiment was performed using six BALB/c mice per group.