The role of CCL2 in AC has also been a source of contention, with some studies suggesting CCL2 deficiency protects against osteoarthritis,54 while other studies claiming CCL2 is necessary for cartilage regeneration55 Accordingly, CCL2 might be decreased due to a negative feedback loop49,53 and thus timing is crucial when considering its role in degeneration. Here, CCL2 is linked to osteoarthritis.