FIGURE 6.

Effect of pan-PI3K inhibition on neutrophil recruitment, apoptosis and efferocytosis in MSU-induced inflammation. Mice were injected with MSU crystals (100 μg) into the tibiofemoral joint and the treatment with intraarticular injection (i.a.) of 50 μM of pan-PI3K inhibitor, 12 h after MSU injection. Cells were harvested from the articular cavity at 18, 24, and 36 h after MSU injection. The number of neutrophils and resolution indices were quantified (A). Of note: ψ_max = maximal number of neutrophils, ψ₅₀ = 50% of the maximum number of neutrophils, T_max = 12 h, the time point when neutrophil numbers reach maximum; T₅₀ MSU+pan-PI3K inhibitor group ∼ 16 h, the time point when PMN numbers reduce to 50% of maximum; and resolution interval R_i MSU+pan-PI3K inhibitor group (γ/δ) ∼ 4 h, the time period when 50% PMN are lost from the articular cavity. (A) Apoptosis assay was evaluated 4 h after treatment, the cells were collected to annexin V analysis (B). Efferocytosis was evaluated in mice injected with MSU crystals (100 μg) into the tibiofemoral joint and 12 h later received an injection of pan-PI3K inhibitor. Cells were collected 18 h after MSU crystal injection and surface-stained with anti-F4/80 for macrophages and then intracellularly stained with anti-Ly6G for neutrophils (C). Results are shown as the mean ± SEM of five mice in each group and are from one experiment representative of two independent experiments. Significance was calculated in relation to the control group (two-tailed unpaired Student’s t-test). The exactly p-value are shown in the figure. ^##means p value < 0.01 compared with 18 h MSU injected.