Fig. 5.

Mice lacking NLRP3 or caspase-1 showed decreased joint pathology in an ank-deficient model of arthritis. (A) Peritoneal macrophages from Ank^+/+ or Ank^−/− mice were either primed with 50 ng/mL LPS for 14 h or left untreated. LPS-primed macrophages were stimulated with ATP (5 mM), Imject alum (500 μg/mL), or indicated dose of HA-3 crystals. Culture supernatants were harvested 8 h later and IL-1β secretion was measured by ELISA. (B) Ank^−/−Casp1^−/− and Ank^−/−Nlrp3^−/− mice were generated and analyzed in comparison with Ank^−/− or Ank^+/− mice of the same generation (Materials and Methods). Frontal sections of the knee joints from 3-mo-old mice of indicated genotype were stained with toluidine blue to reveal gross morphology and cellularity (B, Upper) or stained with Safranin O to examine proteoglycan deposition (B, Lower). Images were obtained at 4× (Upper) and 20× (Lower) magnification and are representative of five mice per group for Ank^+/− and at least seven mice per group for Ank^−/−, Ank^−/−Casp1^−/−, and Ank^−/−Nlrp3^−/−. (Scale bars, 150 μm.) (C) The pathological severity of each joint was scored blindly according to the degree of ectopic mineral deposition, cell infiltration, and proteoglycan loss. **P < 0.01, one-way ANOVA and post hoc test.