Fig. 4

Comparative efficacy of recombinant human proteoglycan-4 (rhPRG4; 100μg/ml), bovine submaxillary mucin (BSM; 25μg/ml), anti-CD44, anti-toll-like receptor 2 (TLR2), anti-toll-like receptor 4 (TLR4) and isotype control (IC) antibodies (2μg/ml for all antibodies) treatments on phagocytosis of monosodium urate monohydrate (MSU; 100μg/ml) crystals by primary peritoneal murine macrophages from Prg4^+/+ and Prg4^−/− mice following a 4-h incubation and production of interleukin-1 beta (IL-1β). Data represent the mean ± S.D. of four independent experiments. *p < 0.001; **p < 0.01; ***p < 0.05. Scale = 50 μm. a Representative images of DAPI-stained peritoneal macrophages from Prg4^+/+ and Prg4^−/− mice with all treatments. Arrows point to MSU crystals localized intracellularly. rhPRG4, anti-CD44, ani-TLR2 and anti-TLR4 treatments reduced MSU phagocytosis by Prg4^+/+ and Prg4^−/− peritoneal macrophages. b Intracellular count of MSU crystals in Prg4^+/+ and Prg4^−/− peritoneal macrophages. A specific effect for rhPRG4, anti-CD44, anti-TLR2 and anti-TLR4 treatments was observed. c rhPRG4 and anti-CD44 antibody treatments reduced IL-1β production by Prg4^+/+ and Prg4^−/− peritoneal macrophages. rhPRG4, anti-CD44, anti-TLR2 and anti-TLR4 treatments reduced IL-1β production by Prg4^−/− peritoneal macrophages. d Representative flow cytometry of MSU-treated macrophages in the absence or presence of rhPRG4 (100μg/ml) for 6 h. e rhPRG4 treatment reduced MSU phagocytosis at 6 h