Figure 3.

Schematic diagram of calcium crystal formation [calcium pyrophosphate dihydrate (CPPD) versus basic calcium phosphate (BCP)], with subsequent inflammasome activation via CPPD and synovial inflammation via BCP, and how both can contribute to the vicious cycle of joint degeneration in calcium crystal-related arthropathies. ePPi, extracellular inorganic phosphate; HA, hydroxyapatite; IL-1β, interleukin 1β; MMP, matrix metalloproteinase; MV, matrix vesicle; NALP 3, NACHT, LRR and PYD domains-containing protein 3; NTPPPH, nucleoside triphosphatase pyrophosphohydrolase; PPi, inorganic phosphate.