PTHLH and rheumatoid arthritis: In the same AIA rabbit model, it was found that the parathyroid hormone related protein (PTHrP) was detected in diseased cartilage chondrocytes, suggesting that it has a role in this pathological condition, with a decrease in cell and matrix PTHrP in late AIA in parallel with the loss of chondrocytes, as happens in human RA cartilage (106).