How can calcium pyrophosphate crystals induce inflammation in hypophosphatasia or chronic inflammatory joint diseases?

Hypophosphatasia (HP) is a rare inborn error of bone and mineral metabolism characterized by a genetic defect in the gene of the tissue non-specific alkaline phosphatase (TNSALP). Calcium pyrophosphate dihydrate (CPPD) crystals are known to accumulate as substrates of TNSALP in tissues and joints of patients with HP. In CPPD-induced arthritis these crystals are known to induce an inflammatory response. HP patients do suffer from pain in their lower extremities however it is not clear whether CPPD crystals contribute to these musculoskeletal complaints in HP. As long as there is no curative treatment of hypophosp…