Figure 1. CAPE suppresses the MSU crystals-induced activation of the NLRP3 inflammasome in primary macrophages.

Bone marrow-derived macrophages (BMDMs) were primed with LPS (500 ng/ml) for 4 hr. The cells were treated with CAPE for 1 hr and then stimulated with monosodium uric acid (MSU) crystals (500 μg/ml) for (A) 4.5 hr or (B–E) 6 hr. In (A), the cell culture supernatants and cell lysates were immunoblotted for pro-caspase-1, caspase-1 (p10), pro-IL-1β, and IL-1β. In (B, C and D) the cell culture supernatants were analyzed for secreted IL-1β, IL-18, and TNF-α using ELISA. The values represent the means ± SEM (n = 3). ^#Significantly different from vehicle alone, p < 0.05. *Significantly different from MSU alone, p < 0.05. In (E), the cell lysates and crosslinked pellets were resolved using SDS-PAGE and were immunoblotted for ASC. In (F), the cells were fixed, permeabilized and stained for ASC (green), and the nuclei were stained with 4′,6-diamidino-2-phenylindole (DAPI; blue). The arrows indicate ASC speckles. The data are representative of three independent experiments. CAPE, caffeic acid phenethyl ester; MSU, monosodium uric acid crystals. DIC, differential interference contrast.