FIGURE 3.

LMW HA induces cPLA₂α and ERK1/2, p38, and JNK phosphorylation. cPLA₂α activation is ERK1/2-, p38-, and JNK-dependent. RAW 264.7 (5 × 10⁵) cells (A and B) or primary human monocytes (1 × 10⁶) (C) were stimulated with 100 μg/ml of HA at the indicated time. Control represents cells treated with the vehicle, which did not change across different time points. The immunoblot is representative of three independent experiments in RAW 264.7 cells (A and B) or in elutriated monocytes from three healthy donors (C), each showing similar results. The bar graph shows the densitometry results, presented as the ratio of phosphorylated to total protein, as compared with the same ratio in the vehicle-treated cells (control). Data represent the mean ± S.E. from three independent experiments. *, p < 0.05 as compared with control. D, RAW 264.7 cells (5 × 10⁵) were treated with ERK1/2 inhibitor (U0126; 1 μm), p38 inhibitor (SB202190, 1 μm), and JNK inhibitor (SP00125, 5 μm) separately or in combination or with the vehicle for 2 h and then stimulated with 100 μg/ml HA for 6 h. Data are presented as the fold change compared with the vehicle-treated cells. Data represent the mean ± S.E. from three experiments, each performed independently in triplicate. #, p < 0.05 as indicated, *, p < 0.05 as compared with HA-only treated cells.